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1,999,700 | Do you put a comma after a title of a book? | Do you put a title of the book in quotes? | When writing an essay do you put the title in quotation marks? | Do you always put a comma before and? | When referring to a book do you underline the title? | Do you underline a book title in essays? | Do you underline book titles or italicize? | Do you put quotes around the title of an art piece? | Awesome book. The only thing that I would change is adding an exclamation point to the title. | 1,999,700 | What punctuation is used ina sentence with a book title? | Do you underline book titles for papers? | What is a book title that starts with K? | Wrong Title - Actually "The First Book of Adam and Eve" | This book is nothing like the title | Title of a book that begins with the letter c? | (Spoilers All) Significance of each book title from context | Do you put a book in quotes? | Unfortunate Choice of Title, Book is Actually a Great Commentary on Current Financial Crisis |
1,999,701 | what is the zoo in coachella valley called | Phoenix Zoo The Phoenix Zoo opened in 1962 and is the largest privately owned, non-profit zoo in the United States. Located in Phoenix, Arizona, the zoo was founded by Robert Maytag, a member of the Maytag family, and operates on of land in the Papago Park area of Phoenix. It has been designated as a Phoenix Point of Pride. The zoo has over 1,400 animals on display and contains of walking trails. It is divided into four main themed areas or "trails:" The Arizona Trail (American Southwest flora and fauna), the Africa Trail (animals from Africa), the Tropics Trail (residents | Denver Zoo); and Richard, Mom, and Oops, the Japanese macaques. Recent additions are red wolves, cinereous vultures, a Canadian lynx, four Asian small-clawed otters, and Pallas's cats (will be out once an exhibit is built). Current animals: Past animals: Animals of the future Mill Mountain Zoo The Mill Mountain Zoo is a zoo located atop Mill Mountain in Roanoke, Virginia, United States. When it opened in 1952, the zoo was operated by the City of Roanoke. In 1976, the city turned its operation over to the Roanoke Jaycees. The Jaycees operated the zoo until 1988 when its operation was handed | Coachella Valley Water District The Coachella Valley Water District is an independent special district formed in 1918, specifically to protect and conserve local water sources in the Coachella Valley. Since then, the district has grown into a multi-faceted agency that delivers irrigation and domestic (drinking) water, collects and recycles wastewater, provides regional storm water protection, replenishes the groundwater basin and promotes water conservation. CVWD's service area covers approximately 1,000 square miles in Southern California from the San Gorgonio Pass to the Salton Sea, mostly within the Coachella Valley in Riverside County, California. The boundaries also extend into small portions of | Coachella, California Coachella (, ) is a city in Riverside County, California; it is the easternmost city in the region collectively known as the Coachella Valley (or the Palm Springs area). It is located east of Palm Springs, east of Riverside, and east of Los Angeles. Known as the "City of Eternal Sunshine", Coachella is largely a rural and agricultural community in the desert and one of the state's fastest growing cities in the late 20th century. When it first incorporated back in 1946, it had 1,000 residents, but the population was 40,704 at the 2010 census. The eastern half | Emperor Valley Zoo The Emperor Valley Zoo abbreviated "EVZ" is the biggest zoo in Trinidad and Tobago. It is located North of the Queen's Park Savannah and West of the Royal Botanic Gardens in Port of Spain. The zoo was first opened on 8 November 1952 by Governor Sir Hubert Rance. At that time, there were 10 cages containing 127 animals, mainly indigenous species. It now has a collection of over 2300 individuals and over 200 species. The zoo was named after the large, blue Emperor or Morpho butterfly which once frequented the valley in which the zoo is situated. | the zoo itself. It was struck by a car approximately three hours later, and subsequently died. In 2002, the zoo became a certified botanical gardens and the official name of the institution was changed to the Los Angeles Zoo and Botanical Gardens. Spread throughout zoo grounds, there are 15 different collections, highlighting over 800 different plant species, with a total of over 7,400 individual plants. Chimpanzees of Mahale Mountains, a one-acre (0.4-ha) exhibit complex, opened in 1998 and houses chimpanzees. The hillside exhibit is dotted with boulders, palm trees, and an artificial termite mound, and features a waterfall next to | the zoo itself. It was struck by a car approximately three hours later, and subsequently died. In 2002, the zoo became a certified botanical gardens and the official name of the institution was changed to the Los Angeles Zoo and Botanical Gardens. Spread throughout zoo grounds, there are 15 different collections, highlighting over 800 different plant species, with a total of over 7,400 individual plants. Chimpanzees of Mahale Mountains, a one-acre (0.4-ha) exhibit complex, opened in 1998 and houses chimpanzees. The hillside exhibit is dotted with boulders, palm trees, and an artificial termite mound, and features a waterfall next to | Gaza Zoo The Gaza Zoo was a leisure complex, series of public gardens, children's amusement park and zoo created by the government of Gaza in the spring of 2010 on government property that was formerly a garbage dump. It closed in 2016. There also is or was a small private zoo, known as Marah Land Zoo located off Salahadin Street in the Gaza City district of Zeitoun. The zoo's animals, like the local people, have suffered as a result of the difficulties in Gaza and the zoo has featured often in reports by the international media. The zoo was badly | 1,999,701 | the nearby Joshua Tree National Park and the new Sand to Snow National Monument to the North, the Santa Rosa Mountains to the south and Mt. San Jacinto Aerial Tram to the west. The Living Desert Zoo and Gardens is located in Palm Desert and has a collection of animals from around the world and hosts the annual Wild Lights Christmas light display. The Coachella Valley History Museum in Indio is devoted to the preservation and interpretation of the Coachella Valley's historical artifacts. Other activities include: The Coachella Valley is served by three public school districts: the Coachella Valley Unified | where is the city of coachella california located | where is the national scouting museum in new mexico | Does anyone know where I can park for the FSU games in Tallahassee? | El Camino Memorial Park | who owns coachella valley music festival in california | Minami-Nagasaki Sports Park | Guadalupe National Park, TX in December? | how many people attended the second coachella valley music festival |
1,999,702 | Favorite movie series/trilogy/saga/etc. ? | Your Favourite Netflix Series ? ( dont need to be only Netflix Original Series )
for me The Last Kingdom / The Haunting of Hill House / Ozark / Stranger Things / Dark / La Casa De Papel / Altered Carbon / Bodyguard / Vikings | Classic science fiction all in one package. One series where the sequels are actually worth watching (unlike the Matrix movies). | What are some of the best comics for characters or stories that started out as movies or TV series?
I've typically found myself not wanting to ruin my perspective of things like star wars and firefly but I've decided they might be worth checking out. What are some of your favorite runs in this genre? | My 3 favorite series are Harry Potter, Twilight, and mortal instruments! I love the characters and the story! Couldn't put the first three books down. Anxious for the last book to come out! | What's another Trilogy?
Examples:
The Red Trilogy: Red Barchetta, Red Sector A, Red Lenses
The Time Trilogy: I Think I'm Going Bald, Time Stand Still, and Dog Years
Credit to Rushcast for using an interesting topic that I could steal. Really, check it out if you haven't. It's super interesting. | I've seen a lot of the sci fi so I'm looking for good recommendations. I love Serenity, Troll Hunter, The Road, Timer, Jericho,etc along with the more well known titles. Do you know of a hidden sci fi gem? I'm a big fan of dystopian and apocalypse movies too.
As far as fantasy, I love all kinds and I'm just looking for a quality tv show or movie. I really fell in love with Lost Girl, I can't resist sexy, dark(ish) fantasy.
Anyway, thanks in advance! | The discs come in a plastic snap case. The discs play fine.
You'll like When Calls the Heart if you like any of the following: Anne of Green Gables (1985), Anne of Green Gable the Sequel (1987), Ann of Avonlea (1975), or Anne with an E (2017- ). All of these series are great family shows, safe for viewers of all ages. You don't have to worry about sex scenes, swearing, or excessive violence.
If you're looking for other good stuff to watch consider miniseries like The Astronauts Wives Club (2015), Band of Brothers (2001), Frank Herberts Dune (2000), Frank Herberts Children of Dune (2003), Into the West (2005), Lonesome Dove (1989), Manhattan (2014-2015), Return to Lonesome Dove (1993), Pride and Prejudice (1995), Taken (2002) and The 10th Kingdom (2000), which are all terrific because they have clear beginnings that establish an objective, then strong middles and conclusive endings where the goal is achieved, like a good novel.
Other shows Ive really enjoyed include Battlestar Galactica (2004-2009), Breaking Bad (2008-2013), Cowboy Bebop (1998), Downton Abbey (2010-2015), Firefly (2002), Game of Thrones (2011-2019), Granite Flats (2013-2015), The IT Crowd (2006-2013), Jericho (2006-2008), Lost (2004-2010), Merlin (2008-2012), The Prisoner (1967-1968), Rome (2005-2007), Spartacus: Gods of the Arena (2011), Spartacus: Blood and Sand (2010), Stargate: SG-1 (1997-2007), Stargate: Atlantis (2004-2009), Star Trek (1966-1969) and Star Trek Voyager (1995-2001). I didn't list any contemporary series Im following that don't have an end date yet, not conducive to binge watching from beginning to finish.
If you like reading try some of my favorite fantasy and sci-fi authors: Richard Adams, Palo Bacigulupi, Suzanne Collins, Abe Evergreen, Diana Gabaldon, Hugh Howey, George Martin, Brandon Sanderson, John Scalzi, and Andy Weir. | Mine are:
1.Empire
2.Rogue One
3. Force Awakens
4.New Hope
5. Return
6. Revenge
7. Clone Wars
8. Phantom | 1,999,702 | I'm bouncing around Reddit whilst watching Lord of the Rings: The Two Towers, and was wondering which movie series was a favorite amongst the redditors.. | favorite movie out of the series | Movies like Lord of the rings series. | I loved the Lord of the Ring series but kept waiting ... | What is your favorite entry in the Total War Series? | Dragon Brigade series | The Pillars of the Earth (miniseries) | Favorite adventure series | Reddit, what's your favorite movie? |
1,999,703 | what are the names of the incredibles characters | The Incredibles (video game) wildly out of control, heavily damaged. Bomb Voyage flees the scene, Mr. Incredible having defeated his madcap foe. Fifteen years later, superheroes across America have been long-since sued and outlawed for causing too much public destruction and are forced by the US government (chiefly the CIA) to disguise themselves as civilians and live normal lives in hiding. Mr. Incredible has married Elastigirl, who has become Helen Parr, and they have three children together: Violet (who possesses force-field and invisibility powers), Dash (a 190+ mph speedster), and Jack-Jack (who does not appear to have obtained any superhuman abilities). After narrowly escaping | The Incredibles previous Pixar productions which typically had two or three directors and as many screenwriters with a history of working for the company. In addition, it would be the company's first film in which all characters are human. Bird came to Pixar with the lineup of the story's family members worked out: a mom and dad, both suffering through the dad's midlife crisis; a shy teenage girl; a cocky ten-year-old boy; and a baby. Bird had based their powers on family archetypes. During production, Hayao Miyazaki of Studio Ghibli visited Pixar and saw the film's story reels. When Bird asked if | Helen Parr (The Incredibles) to their personality. He felt that as a mother, Helen was required by society to be pulled in many different directions, which led to her being given an elastic ability. Regarding the choice to make Helen the star of "Incredibles 2", Bird insisted that it was unrelated with the #MeToo movement, and was instead a choice that came naturally with how the writers wanted to progress the story. In "The Incredibles" (2004), Helen is seen as Elastigirl in the time before superheroes are banned. She married Bob Parr (Mr. Incredible) and starts a family: Violet, Dash, and Jack-Jack. She gives | Craig T. Nelson Craig Theodore Nelson ( born April 4 , 1944 ) is an American actor and former comedian who is known for his roles as Hayden Fox in `` Coach '' and as Mr. Incredible in `` The Incredibles '' . | Incredibles 2 She plans to sabotage her brother's summit and cause a catastrophe that will tarnish the reputation of superheroes, ensuring they remain outlawed forever. Using a hypnotized Elastigirl, she lures Mr. Incredible into a trap, then sends other hypnotized superheroes to subdue the Parr children. Frozone tries to protect them, but is overwhelmed and placed under Evelyn's control. Violet, Dash, and Jack-Jack escape with the help of the Incredibile, a high-tech car once owned by Bob during his time as Mr. Incredible, and reach Winston's ship. On board, the hypnotized Mr. Incredible, Elastigirl, and Frozone recite a vindictive manifesto on air | Helen Parr (The Incredibles) Helen Parr (née Truax) is a fictional superhero, created by Brad Bird for the Pixar franchise "The Incredibles". The character is voiced by Holly Hunter in the films and in the "Disney Infinity" video game franchise, while Elizabeth Daily and Ally Johnson voiced her in "The Incredibles" video game and "Lego The Incredibles". Helen has an elasticity-based superpower that allows her body to stretch and contort in a variety of ways. Helen Parr is also known by her superhero name Elastigirl. When designing the Incredibles family, Brad Bird wanted each of their superpowers to be related | The members of the Incredibles assumed for this would be Mr Incredible, Elastigirl, Dash, and Violet unless stated otherwise. Incredible would have the mind of Mr Incredible, but with the experience of the others in addition to his own.
* Round 1: Incredible vs Venom
* Round 2: Incredible vs Carnage
* Bonus 1: Rounds 1 and 2 with the addition of Frozone's abilities.
* Bonus 2: Rounds 1 and 2 with the addition of Jack-Jack's shown abilities only. (No further speculation on powers)
* Bonus 3: Rounds 1 and 2 with Jack Jack's and Frozone's abilities added.
The fight will take place in the downtown area where The Incredibles' major fight scene occurred. | The Incredibles go toe to toe with Kid Flash, Robin, Miss Martian and Aqualad. Who comes out on top? | 1,999,703 | The Incredibles (video game) wildly out of control, heavily damaged. Bomb Voyage flees the scene, Mr. Incredible having defeated his madcap foe. Fifteen years later, superheroes across America have been long-since sued and outlawed for causing too much public destruction and are forced by the US government (chiefly the CIA) to disguise themselves as civilians and live normal lives in hiding. Mr. Incredible has married Elastigirl, who has become Helen Parr, and they have three children together: Violet (who possesses force-field and invisibility powers), Dash (a 190+ mph speedster), and Jack-Jack (who does not appear to have obtained any superhuman abilities). After narrowly escaping | how many children does mr incredible have in incredibles | who owns the rights to incredible machine | when did the show that's incredible come out | where is the incredible human journey filmed | who does the voice of edna mode in the incredibles | what are the names of the aliens in amazing planet | how much did incredibles 2 gross at the box office | how many minigames in incredible crisis |
1,999,704 | How good is Gigabyte GeForce RTX 2070? | As the title says, is it any good?
Is it any good at $320 for a year old GPU? Or should I avoid blower style GPUs?
Edit: Thanks everyone for the answers, I was hoping it may be decent but I did have doubts which is why I ask.
I wanted to go for any RTX due to DLSS but I found this one and older RTX cards are out of stock for some reason and what is left is insanely expensive for some reason (2070 is $795, 2070 Super is $930, 2060 Super $680 and new 5700XT is close to $700) | I'm going to be building a new computer over the summer, and I saw the RTX 2070 was on sale]( The reviews seem mixed, I'm not planning on overclocking it at all, so should I buy this or just get an older gpu? Also pcpartpicker says there may be some compatibility issues with my cooling. [Here's the list if anyone could check that out for me :) | Link
I'd like to compare it to the Sapphire Nitro 390, but I still haven't found any reviews or benchmarks for Gigabyte's card anywhere. | Hi, need information regarding RTX 2070 WINDFORCE. How long have you had this GPU and so far, how is it holding up?
Any artifacting or glitches issue?
Please tell me your review about it.
Thanks | Hi guys.
So a Beginner here, I tried to mess with settings in MSI Afterburner to get the best settings and these was the best in terms of Hash rate but some people say it could go for higher
Gigabyte RTX 2070 Super 8GB.
So do you think these are the best settings right now? Also would it affect the card badly in 6 months - 1 year, Because it is my main card and i game on it aswell and don't plan to change it anytime near in future.
Thanks. <3
| In terms of value, the 2070 Super is a great option for people looking to build a high-end gaming PC. It places at the top of the charts for the FPS per unit of money spent on a complete PC. If you're only looking at the graphics card, however, the RTX cards—and really any high-end GPU—look far less enticing. | I am looking at shopping a used GPU for the upcoming shopping season, and are looking at an used RTX 2070, not the super that came out this year, but the older one that was on the market in 2018. I already saw refurbed ones that are on sale from newegg for less than $400, and I think that's a pretty good deal for a mid market ray tracing card.
Currently I am using a RX570, playing on 144 hz 1080p. I want to ask here, anyone here have the RTX 2070 card? How is performace on remastered, anytime fps goes down below 60? It's either that card or a used RTX 2080. | Hi, here is my current build , I mainly play esport titles but I have to tweak the settings to get constant 144 fps. I'm in a good month and so I would want to futureproof my pc and have around 500€ to buy a new gpu. In term of overall performance I thinks a 1080ti is better than a rtx 2070 for the same price (here at least). What do you think about this ? Is it worth an upgrade from a gtx 970 and is worth this price ?
Edit : I didn't see there was a recent post answering the question about the price. So I guess it's only a matter of is it worth upgrading from a gtx 970 ?
Edit 2 : thanks for your answers I bought it. | 1,999,704 | Hi everyone, I'm upgrading my PC and I was wondering which GPU I should pick.
The card mentioned seemed pretty sweet, but it had shit reviews. I do remember Gigabyte having good quality GPUs, has that changed?
Also, I was hoping I can maintain my i7-6700K CPU after changing GPUs. Will that be an issue?
Exact card I'm talking about:
GIGABYTE GeForce RTX 2070 WINDFORCE 8G Graphics Card, 3 x WINDFORCE Fans, 8GB 256-Bit GDDR6, GV-N2070WF3-8GC Video Card | Upgrade opinions: New CPU or GPU? | What GPU should I get? (Upgrading from RX580) | To get better performance, should I upgrade my cpu or gpu | Thinking about upgrading graphics card, what do I choose? | Upgrade question, CPU or GPU? | How much of a performance difference can I expect with this GPU upgrade? | Video card upgrade question, good choice? | Need Help Upgrading My GPU |
1,999,705 | [TOMT][90s point and click adventure game] Lady takes comb out of inventory; cries into hands briefly | **Platform:** Flash
**Genre:** Puzzle
**Estimated year of release:** bellow 2010
**Graphics/art style:** simplistic, 2D
**Notable characters:** Tom, The Old Man
**Notable gameplay mechanics:** Click and using items
**Other details:** Took place in an old castle?
Issue here is that the memory of the game is very vague. The game was a flash game, it wasn't very fancy as it was an old flash game I played 2010 and before that. It was a point and click game where you played as a man and tried to solve puzzles in an old castle. The biggest staple of the game was a character called Tom, which was short for The Old Man. There were multiple games to this. It's not a lot of detail and I apologize, it's been many years since I've thought of it. | Some point in the late 90s (maybe early 2000's), there was an educational computer game (I think it was on a Mac) about bugs. It featured a professor or doctor named Ants in pants or something along those lines. You would click around an interactive screen that was either a zoom out or zoom in of an environment. I remembered there being an outdoor yard and an indoor kitchen scene. It seemed like a traditional educational computer game from the 90s-2000s ala Pajama Sam | [TOMT] [GAME] [2000’s] I have a very vague memory of this, but I’m genuinely going crazy because I can’t remember what exactly this is.
So essentially, it was a handheld virtual pet(?) game where you could travel from your house with a pet, into your yard, out into the street. You could go into other people’s house on the streets and see their pets. You could go to a pier near the beach. It was a 2D game, I think it’s similar to pixel chix. Please help, I am not gonna stop thinking about it
The pet could sleep in its bed in your house, then you go out in your yard and I think there were toys and stuff. It was pretty basic but it’s more involved than a basic tamagotchi | Ark of Time is a 1997 adventure game developed by Italian studio Trecision and published in 1997 for MS-DOS by Koei. A PlayStation version was released in 1998.
Plot
Players control Richard, a newspaper reporter whose search for a missing professor takes him around the world and entangles him in the mystery of the fate of Atlantis.
Gameplay
Ark of Time is a third-person point-and-click adventure game, with mostly inventory based puzzles.
Reception
Giving the game 80/100, Tap-Repeatedly/Four Fat Chicks complimented the game's sly sense of humor. AdventureGamers rated the game 70/100, saying "This is the worst game that I've totally enjoyed." GameSpot gave it 63/100, writing that Ark of Time was neither revolutionary or groundbreaking. Quandary game the game 60/100, writing that the game was part of a rush of titles centering around the fabled lost city of Atlantis that were released at the time. Additionally, Quandary felt that it was surprising. Gameboomers wrote that the game was 'pretty okay'. Just Adventure felt the title was loony and offbeat. Meristration flet that while the game was competent and didn't have any serious flaws, it lacked anything that pushed the genre.
References
External links
PC Games review
Koei games
1997 video games
Adventure games
Point-and-click adventure games
DOS games
PlayStation (console) games
Video games developed in Italy
Video games set in 1997
Video games set in Atlantis
Video games set in London
Video games set in the Caribbean | I created a clicker game for the community of Town of Salem.
Have fun and please give me feedback so i can learn on what needs to be changed or kept. Thanks.
Its still a work in progress so please report problems to me as well. | Adventure Time (season 9) April 2017 as part of season nine. It was first announced on March 31, 2017, by Cartoon Network during the unveiling of their 2017–18 program lineup. "Elements" follows Finn, Jake, and BMO after they return home to discover that elemental magic has turned Ooo into a dystopia. Finn and Jake join the Ice King (voiced by Tom Kenny), Betty (voiced by Felicia Day), and Lumpy Space Princess (voiced by Pendleton Ward) to set things straight. The season's voice actors included Jeremy Shada (Finn the Human), John DiMaggio (Jake the Dog), Tom Kenny (the Ice King), Hynden Walch (Princess Bubblegum), and | We have released the demo for our 2d/Horror/Puzzle Game "The Lady" on our IndieGoGo page.
Get the DEMO Here.
Gameplay Trailer
Teaser Trailer
Vote/comment/follow our new [Steam Greenlight Page(
Follow us on Twitter
**"The Lady"** is a 2D Surreal/Puzzle/Adventure game, with horror elements. The game features hand drawn character art, photographic backgrounds, stop-motion themed animation, and a hauntingly abrasive analog soundtrack.
The Lady is a short and surrealist journey that takes The Lady through a series of fever dream hallucinations, while being at odds with her own inner struggles of anxiety and depression. She encounters multiple versions of herself throughout the game, unsure of which versions to trust.
Inspired by classic SNES and Turbo Grafx16 type games, gameplay features side-scrolling exploration and arcade-style battles. The difficulty level will be brutal like old school games, reminiscent of titles such as Ghost N Goblins. The game plays in letterbox full screen HD. Best played with the lights off and good speakers or headphones. | My wife is thinking of getting into LPing. Her main interests lie with adventure games...leaning more toward the point-and-click adventure games rather than action-adventure.
Does anyone have some good examples of adventure game LPs she can watch as a point of reference? If you are doing (or have done) a point-and-click adventure game LP yourself, feel free to post a link to it. | 1,999,705 | I watched my mom play this game in the late 90s. I remember almost nothing about it because I watched it for a short portion of time. But it was so interesting that it somehow had a lasting effect on me anyway, so I want to perhaps play it (if it could be played on my machine). The player character (or perhaps one of them?) was a lady, middle ageish, I think with a blue dress and also I think with a blonde-haired bun. She had an inventory and could walk around and click on things to inspect them or interact with them. She has lost her daughter (I think). On her person she has a comb that belongs to her daughter, and if you try to use it from the inventory, the PC takes it out, looks at it, and cries for a minute before putting it away.
Thanks! | Trying to remember a childhood computer game | Trying to remember old PC toy story game | [PC][1990-2000ish]A same-tone point and click adventure game where you did not see your own character. Played a woman. | Need some help getting my hands on an old game. | Mojo Jojo lab combination game from Power puff girls franchise. [PC/browser flash ][early 2000's] | Trying to remember childhood game | Classic game I use to play with my mom it ... | Looking for an easy game for my mum to play (Point-and-click type) |
1,999,706 | Jack is not dead! (Theory) | I was just looking at the wiki and he is listed as deceased. It seems to assume he died when his brother Joe Baker punches his head to pieces st the end of the dlc. But that got me to thinking about the main game when Jack lost his entire upper body including his head after the chainsaw fight and was able to regenerate. Hell he was even able to regenerate from a serum designed specifically to kill the mold in him that ended up freaking calcified his cells. How could punching his head off suddenly kill him after he has been shown to shrug off that type of damage before? His regen factor comes across to me as absurdly high even in the REverse. What do you all think? Is it probable that Jack is still alive out there in the verse? | Does anyone know what happened to jacks At Dead Of Night series? i really enjoyed him playing that and he kinda just stopped mid way through. Does anyone know what happened or if he will keep playing it? | Is really jacky chan dead? | I have been thinking a lot on this possibility.
After the events of TPS, Jack may have witness his death on the vision.
Knowing this, he got one of his doubles and posed him as the real Jack. He later uses Angel, which her Siren powers over technology could have make it easy for him to transfer his entire self to a computer.
Reasons why I think this happens:
* We are really being teased with Jacks double(Timothy). We even doubt the Jack we work for on TPS is the real Jack
* His appearance on Tales. He is practically an hologram. And knowing he is dead and his appearance on Tales is a double makes me think the other way around. The one dead may be his double.
* His semi-canon missions on BL2, stating he might be dead when you talk to him via those missions
What are your thoughts? | What are other things you think about Jack living through, especially during the mid-to-late-20th Century?
If he lived an 80 year lifespan, he would've died in 1975. He would've seen the development and cultural changes from the period we know him from to the period we live in, and I just think it's cool that Jack might've read Lord of the Rings or seen an episode of Star Trek. | As he escaped, he is then stabbed in the spine by Bullseye, puncturing his cauda equina and apparently leaving him paralyzed. Bullseye states that Flag would "never walk again". He is then taken into custody, where he is severely beaten by an enraged Swordsman. Jack Flag is later shown leading the prisoners of the Negative Zone prison against Blastaar's army, which he does so from a wheelchair. After escaping with the Guardians of the Galaxy, Jack's spine is repaired, in two minutes, by Knowhere's medical staff. He opts to remain on the station rather than return to Earth (where he | I will keep this short and sweet.
Jack being Jack, likes to go a little over the top. He's worked hard at being a surgeon and he never gives upnbecauses he's a stubborn man. Even by the end of the show, he doesn't recognize stubbornness as a weakness but utilizes it to fulfill his role and kill the MiB.
His determination to kill the MiB comes from his interactions with both him and Jacob. He accepted the role of protector from Jacob, before giving it to Hurley. He recognized Hurley and Jacob were kindred souls, both kind and caring. Hurley would be a better Jacob.
So what does that leave Jack? Jack realizes he is the better defense system for the island. He recognizes the duality the island had with the smoke monster (MiB) and Jacob, both protecting it in their own way and both being brothers were two halves of a whole. So he accepts the role of the muscle, and goes after MiB.
Here's where it gets interesting. We know the MiB couldn't be killed until he was disconnected from the source and the cork was removed. Doing so disconnected everyone from their power. In killing MiB, he dies a mortal. As Jack lay dying, the cork is returned. And we seem him go to the afterlife where his friends are waiting for him. They say they were waiting. But if he died first how are they waiting?
Jack didn't leave the island after he died. Accepting the role of muscle, of security, he remained as the islands protector like he promised he would to Jacob. He gave the job to Hurley, because Hurley was so like Jacob in their gentle demeanor. But he knows the island needs a yin and a yang, a black and a white piece, so he remained taking the role that the Smoke monster had. Not necessarily as the smoke monster, but to help protect the island in ways that Hurley cannot.
It was only after years of being the protector, likely after the island had sunk for good, and all had moved on, that he was then reunited with his friends. Which is when he 'woke up' in the flash sideways | Dead No More: The Clone Conspiracy airstrip where Jackal is receiving a large box and attacks him. Peter is surprised that Jackal is able to get the upper hand on him with enhanced strength and speed. Jackal takes off his mask and reveals himself to not be Miles Warren, but none other than Ben Reilly. He offers Peter the chance to bring back Uncle Ben as his corpse is in the large box. In the Jackal's laboratory, Doctor Octopus is studying Kaine and Electro to perfect his "proto clone." Anna Maria is brought into the lab and becomes uncomfortable when Doctor Octopus starts appealing toward his | 1,999,706 | I believe Jack is not dead. My theory is that someone else stole his car and ring and then crashed and burned! Jack must have lost his memory or be in a coma (Probably he got beaten or something), probably Jack's father was notified of this by a friend or family, and took care of him, and he never notified Jack's family because Jack's father never knew that he was married or had a family, that's why the family think he is dead and spread the ashes of the "other" person that was driving! Who was probably totally burned after the accident... And with the ring they really thought that was him... I hope I'm right... Lol
Jack is not dead | A theory about Jack dying because he “was sick” | who killed jack in lost the end | when did jack johnson die in a car crash | Why did jack Halagey said that he died like jesus? | Who was the victim of jack the ripper? | when did jack in the box blew up the clown? | [Unexplained Death] Who Killed Jack Nance? | Lost- Jack remained on the island after his death |
1,999,707 | New beta features on Ancestry - tags, notes, groups, filters! | I got an email saying "your new ancestry reports are available" but nothing has changed. What is new exactly ? Did anyone's results change ? | Hey all!
So I'm currently making an effort to collect as much genealogical information about my family as possible. The goal is to gather as much concrete info as I can before the older generation passes on and than combine my family tree with my wife's for the future benefit of our kids.
Now, I've had a Geni account for ages and I really dislike that platform. It isn't really user friendly, it looks outdated, other users can make changes to your tree, I just don't like it. Are there any free platforms you guys could recommend? It doesn't need to be fancy, just something usable and clear that allows a little flexibility with adding several names, locations, or little notes to people. Any help would be appreciated.
Thanks! | Hi, one of my players really wanted to play a Loxodon, and because of it, I brewed an ancestry for him. Because my experience with the system is limited, I would really appreciate feedback in terms of the strength of its features.
The ancestry can be seen in this google doc:
Loxodon Ancestry
Thank you in advance | With the advent of DNA testing, this classic research work is a must for pinpointing the various Irish and Anglo-Irish branches on a family tree with Irish roots. | Cultural heritage institutions have recently begun to consider the benefits of sharing their collections using linked open data to disseminate and enrich their metadata. As datasets become very lar... | Thanks to television shows such as `Who Do You Think You Are', researching your family history has quickly become a popular hobby and this book proves to be a good first guide for beginners to genealogy. With plenty of web-links and useful contacts throughout, both free and paid, this book takes away some of the initial confusion as Fowler provides his expert opinion on the best ways to track down your ancestors. Personally, I would have appreciated a short summary of important websites at the end, as sometimes the information load is quite overwhelming; yet, the short length makes this guide easy enough to dip in and out of at your leisure. I'd recommend this to others as a starting point for researching their family tree before sampling more in-depth (but certainly more expensive) titles on the market. | My nan currently uses Ancestry but she can't find any information on a certain relative from the 1800s. She thinks she might find it on My Heritage, but she's very nervous about signing up to new things.
So in short, is My Heritage any good? How does it compare to Ancestry? | Hi /r/germany,
My wife's great grandpa (Otto Nagl 27/02/1890 Munchin Germany) and grandmother (Anna Fritz 9 January 1901) seem to be getting me stuck. At this point a lot of things turn from english documentation, to german documentation, and I dont really know where to look.
Any recommendations on where I can search further on ancestry in Germany?
Thanks for the help!
Deten | 1,999,707 | Has anyone else seen the new beta features on Ancestry (Australian site)?
One of my DNA results came in today so I logged on and saw there was a notification on the Extras menu for "Ancestry Labs", which I'm sure wasn't there the other day.
There are two beta features that you can enable, "MyTreeTags" which allows you to put all sorts of different tags on people on your tree, as well as write notes and comments, and "New and Improved DNA Matches" which allows you to put your DNA matches into groups, and to filter them.
I haven't played around with them yet but they look super helpful.
Screenshots here:
Maybe I'm way behind the times but I haven't seen anyone talking about them on here yet, so I did a quick search and could find any other posts. | DNA / Genealogy kits, have you tried and do they work? | Ancestry (Canada) DNA test kits on sale at Amazon (Canada) | Good Genealogy Research tool | AncestryDNA health? anyone try it yet? | are ancestry dna kits accurate? | Direct-to-consumer DNA Testing Experience Survey | Ancestry.com trial - what can I get here but not elsewhere? | Has anyone here had both 23andme and AncestryDNA? |
1,999,708 | Inhibition of TNFa in Patients with Concomitant HCV Infection; Molecular Insights and Safety | The review considers the chemical structure, pharmacodynamics and pharmacokinetics of telaprevir, a new direct-acting antiviral agent, used to treat patients with chronic hepatitis C (CHC). The given data on Phase II and III clinical trials enable the authors to state the high efficacy of the drug in patients infected with hepatitis C virus type 1. The paper also provides data on the resistance of telaprevir and its drug interaction and denotes the place of the drug in the current antiviral treatment of patients with CHC. | Hepatitis C virus (HCV) has evolved complex strategies to evade host immune responses and establish chronic infection. Since human Vc9Vd2 T lymphocytes play a critical role in the immune response against viruses, we analyzed their antiviral functions on Huh7 hepatoma cells carrying the subgenomic HCV replicon (Rep60 cells). In a transwell culture system, Rep60 cells were co-cultured with either PBMCs or highly purified cd T cells stimulated by non-peptidic antigens. Vc9Vd2 T cell activation was associated with a dramatic reduction of HCV RNA levels. Neutralizing antibodies targeting IFN-c revealed a critical role for this cytokine in the inhibition of HCV replication. Interestingly, drugs already in clinical use, such as Phosphostim and Zoledronate, known to activate cd T cells, were shown to induce the inhibition of HCV replication mediated by Vc9Vd2 T cells of HCV patients. Our data suggest that the therapeutic activation of Vc9Vd2 T lymphocytes may represent an additional strategy to inhibit HCV replication and to restore a Th1-oriented immune response in HCV-infected patients. | The immune response in patients chronically infected with HCV plays a unique role during the infection because of its potential to contribute not only to viral clearance and, in some cases, protective immunity, but also to liver injury. A detailed understanding of the immunological mechanisms involved in persistence to HCV is essential to fully appreciate the complexity of the disease. In recent years, enormous progress has been made to characterize the dysfunctional natural killer cells and T cells during the chronic phase of infection. This information is important to further optimize treatment strategies based on the strengthening antiviral and immunomodulatory activities in patients chronically infected with HCV. | siRNAs: Potential therapeutic agents against Hepatitis C Virus | During last years knowledge about HCV virus was growing very fast. Because of that some reviews on molecular structure of this virus was presented. They are clinically important for diagnosis, prognosis of treatment and possibility of production a new antiviral drugs. | BACKGROUND ::: Hepatitis C virus (HCV) infection is widespread, abhorrently under-diagnosed, and radically under-treated. Globally, infection with HCV is a major cause of acute hepatitis and chronic liver disease. Therefore, novel HCV inhibitors are required for the treatment of the HCV infected patients. ::: ::: ::: OBJECTIVE AND PERSPECTIVES ::: This review gives the detailed knowledge of upcoming therapy such as NS5B polymerase inhibitors that are urgently needed. ::: ::: ::: CONCLUSION ::: In the past decade, intensive hard work has focused on the discovery of both structural and nonstructural inhibitors of the HCV NS5B polymerase. These demanding efforts have resulted in various promising agents advancing in clinical development with emphasis on clinical efficacy and impact for future combination studies. | The aim of this study was to gain insight in transmission routes of hepatitis C virus (HCV) infection among never-injecting drug users (DU) by studying, incidence, prevalence, determinants and molecular epidemiology of HCV infection. From the Amsterdam Cohort Studies among DU, 352 never-injecting DU were longitudinally tested for HCV antibodies. Logistic regression was used to identify factors associated with antibody prevalence. Part of HCV NS5B was sequenced to determine HCV genotype and for phylogenetic analyses, in which sequences were compared with those from injecting DU. HCV antibody prevalence was 6.3% and HCV incidence was 0.49/1000 PY. HIV-positive status, female sex and starting injection drug use during follow-up (a putative marker of past injection drug use), were independently associated with HCV prevalence. The main genotypes found were genotype 3a (50%) and 1a (30%). Phylogenetic analysis revealed that HCV strains in never-injecting DU did not cluster together and did not differ from HCV strains circulating in injecting DU. We found a higher HCV prevalence in never-injecting DU than in the general population. Phylogenetic analysis shows a strong link with the injecting DU population. The increased risk could be related to underreporting of injecting drug use or to household or sexual transmission from injectors to noninjectors. Our findings stress the need for HCV testing of DU who report never injecting, especially given the potential to treat HCV infection effectively. |
INTRODUCTION
Hepatitis E virus (HEV) infection is one of the most common causes of acute hepatitis or sporadic acute hepatitis in many parts of the world [1] . At least 20 million HEV infections occur annually, which are mostly selflimiting and have different clinical manifestations, such as asymptomatic, acute liver failure and rare chronicity [2,3] . In some cases, HEV infections can cause up to 30% mortality in pregnant women [4] and may result in chronic hepatitis in immunocompromised individuals, such as those receiving organ transplants or chemotherapy, and individuals infected with human immunodeficiency virus [5][6][7] . Currently, at least four genotypes exist among HEV strains, of which HEV genotypes 1 and 2 are obligate human pathogens and HEV genotypes 3 and 4 are mostly zoonotic [8] . Recently, a study found that a genotype 3 HEV isolated from a chronically infected patient could be adapted to grow in human C3A hepatoma cells [9] . HEV has a 7.2-kb single-stranded, positive-sense RNA genome containing three open reading frames (ORFs) [10] . The ORF1 protein comprises the functional domains of virions. ORF2 is the major structural protein of virions and encodes the viral capsid protein. And, ORF3 protein, a small molecule phosphoprotein, is involved in viral particle secretion [11] . A recent study found that chronic HEV infections were almost exclusively caused by the zoonotic genotype 3 HEV strains [12] . Type Ⅰ interferons (IFNs) are key components of innate immunity and known to be the first-line defense against virus infection. IFN exerts many biological effects, such as antiviral and antitumor activity, and immune regulation by activating hundreds of downstream IFN-stimulated genes (ISGs) [13,14] . One of the most abundantly IFN-induced proteins is ISG15, which is encoded and expressed as a ubiquitin-like protein. ISG15 is covalently attached to target proteins through a C-terminal LRLRGG motif, in a process called ISGylation. ISGylation could alter protein properties directly by addition of ISG15, as well as by reducing the degradation of the target protein by competing with ubiquitin conjugation [15] . Previous studies have shown that ISG15 is critical for control of certain viral and bacterial infections and is linked to the process of budding or egress for many RNA virus families [16][17][18] .
As few studies have focused on the role of ISG15 in HEV infection, we investigated whether HEV infection could regulate the expression of ISG15 and the impact of ISG15 on IFN production during HEV infection in the present study, which is of great significance to expand our understanding of the interaction between ISG15 and HEV pathogenesis.
MATERIALS AND METHODS
Cells and virus
C3A is a derivative of HepG2 cells (hepatoma cells). C3A cells were obtained from the American Type Culture Collection (ATCC) (Manassas, VA, United States) and cultured in Dulbecco's Modified Eagle's Medium supplemented with 10% fetal bovine serum (Gibco, Thermo Scientific, Waltham, MA, United States), penicillin (100 U/mL) and streptomycin (100 μg/mL) at 37 ℃ with 5% CO2. The genotype 3 Kernow-C1 HEV infectious cDNA clone was a kind gift from the National Institute of Diagnostics and Vaccine Development in Infectious Diseases (NIDVD, Xiamen, China). The ATG start codon of ORF3 in Kernow-C1 HEV was altered to GTG to construct an HEV ORF3 mutant, which led to the loss of ORF3 protein expression.
Reagents and plasmids
Anti-ISG15 antibody was purchased from Signalway Antibody (42509, 1:1000 dilution; Pearland, TX, United States). AntiHEV ORF3-specific antibody was purchased from Abbiotec (250688, 1:1000; San Diego, CA, United States). Primary antibody against β-actin (#BM0627, 1:400 dilution) was purchased from Boster (Wuhan, China). We constructed a plasmid-expressing ORF3 (ORF3) as well as a plasmid-expressing ISG15 (ISG15). ORF3 and ISG15 fragments were cloned into the pEGFP-N1 vector (green fluorescent protein (GFP)expressing, GenBank accession #55762) by digesting with Xho Ⅰ and Hind Ⅲ to construct the pORF3-EGFP plasmid (ORF3) and pISG15-EGFP plasmid (ISG15). All the clones were confirmed by restriction digestion and DNA sequencing.
HEV infection
Th cDNA clones were linearized with BglⅡ, and the genomic RNA was transcribed using the MEGAscript Kit (Ambion, Thermo Scientific). C3A cells cultured in a sixwell plate were transfected with capped RNA transcripts from Kernow-C1 HEV infectious cDNA clone using DMRIE-C reagent (Invitrogen, Grand Island, NY, United States) following the manufacturer's protocol. The ratio of RNA to DMRIE-C was 2 μg:8 μL. After 6 h, the medium in the six-well plate was removed and replaced with serumfree medium. The cells and cell culture supernatants were harvested at different time points (0, 8, 12, 24, 48, 72 and 120 h) and used in experiments.
Cell transfection
C3A cells were plated in six-well microplates and transfected with a plasmid-expressing ORF3-EGFP (ORF3) or the HEV mutant, leading to the loss of ORF3 protein expression (ΔORF3) using Lipofectamine TM 3000 Transfection Reagent (Invitrogen, San Diego, CA, United States) for 48 h. Then, the cells and cell culture supernatants were harvested at different time points (0, 8, 12, 24, 48, 72 and 120 h) and used in experiments.
Small interfering RNA-mediated knockdown
The small interfering RNAs (siRNAs) targeted against ISG15 were purchased from Santa Cruz Biotechnologies (Dallas, TX, United States). C3A cells were transiently transfected with 20 nmol/L of siRNA using the DMRIE-C reagent (Invitrogen) according to the manufacturer's protocol. Primers are shown in Table 1.
Enzyme-linked immunosorbent assay
The concentrations of IFN-alpha and -beta (-α/β) were evaluated in cell culture supernatants using a human IFN-α/β ELISA kit (Joyee Biotechnics, Shanghai, China).
All samples were tested in triplicate.
Western blot analysis
Cells were lysed in RIPA buffer (Beyotime Biotechnology, Shanghai, China), and the protein concentration was determined using an enhanced BCA protein assay kit (Beyotime Biotechnology). Ten micrograms of each protein sample were separated on 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis and subsequently transferred to polyvinylidene difluoride membranes. Samples were then incubated with specific primary antibodies overnight, following incubation with an antimouse secondary antibody solution for 2 h at room temperature. The blotted membranes were exposed to film, and the protein bands were visualized by a scanner system.
Real-time reverse transcriptase-polymerase chain reaction
Total RNA from C3A cells was isolated using Trizol (Thermo Scientific) and reverse-transcribed into cDNA using the TaqMan Reverse Transcription Reagents (Thermo Scientific). The mRNA level of ISG15 was quantified by real-time PCR using SYBR master mix (Thermo Scientific). The PCR amplification conditions included 1 cycle of 95 ℃ for 2 min, and 40 cycles of 95 ℃ for 10 s, 60 ℃ for 20 s, and 72 ℃ for 30 s; the Roche Light Cycler 480 Ⅱ Real-Time PCR System was used. Threshold cycle (CT) values were determined by RT-PCR and normalized by the housekeeping gene β-actin. The mRNA abundance was calculated using the 2 −ΔΔCt method and expressed as fold-change. Primers are shown in Table 1.
Statistical analysis
All the data are presented as mean ± SD. Statistical differences between the samples and the controls were assessed by the Student's t-test. P < 0.05 was considered statistically significant.
RESULTS
HEV infection enhances the production of IFN-α/β and induces elevation of ISG15 protein in C3A cells
In this study, C3A cells were transfected with HEV RNA.
Name
Primer Sequence concentrations of IFN-α/β increased the maximum at 24 h (Figure 2A). The ORF3 group could induce higher ISG15 protein expression than ΔORF3 group (P < 0.01). ISG15 protein was poorly expressed in the early stage, from 0 h to 12 h, and significantly increased at 24 h, reaching the maximum at 72 h ( Figure 2B).
β-actin Forward 5'-AGCGAGCATCCCCCAAAGTT -3' Reverse 5'-GGGCACGAAGGCTCATCATT -3' ISG15 Forward 5'-GCGCAGATCACCCAGAAGAT -3' Reverse 5'-GTTCGTCGCATTTGTCCACC -3' siRNA1 Forward 5'-UGUCGGUGUCAGAGCUGAATT -3' Reverse 5'-UUCAGCUCUGACACCGACATT -3' siRNA2 Forward 5'-GAUGCUGGCGGGCAACGAATT -3' Reverse 5'-UUCGUUGCCCGCCAGCAUCTT -3' siRNA3 Forward 5'-UGAGCACCGUGUUCAUGAATT -3' Reverse 5'-UUCAUGAACACGGUGCUCATT -3' Negative control Forward 5'-UUCUCCGAACGUGUCACGUTT -3' Reverse 5'-ACGUGACACGUUCGGAGAATT -3'
ISG15 silencing enhances the production of IFN-α/β in C3A cells
To investigate the levels of IFN-α/β when ISG15 was inhibited, we first constructed three siRNAs that could inhibit the expression of ISG15 and then transfected them into C3A cells, respectively. Then, the mRNA and protein levels of ISG15 were detected to determine which siRNA had the best inhibitory effect ( Figure 3A and B). The siRNA2 was found to have the best inhibitory effect on ISG15. Next, the siRNA2 was transfected into C3A cells that had been pretreated with HEV RNA. The expression of IFN-α was significantly increased in the HEV-infected C3A cells transfected with siISG15 compared to the HEV-infected cells (P < 0.05).
Consistently, the expression of IFN-β showed the same trend (P < 0.01) ( Figure 3C).
Overexpression of ISG15 results in the reduction of IFN-α/β in C3A cells
To investigate the effect of ISG15 overexpression on IFN-α/β, the plasmid -expressing ISG15 was constructed and transfected into C3A cells. The level of ISG15 was Figure 1A). Next, we identified whether HEV could induce ISG15. ISG15 protein expression was detected at different time points by western blotting. It showed HEV enhanced the expression of ISG15 (P < 0.01) and ISG15 protein expression reach the maximum at 24 h as compared to the control group (Figure1B).
HEV ORF3 protein enhances the production of IFN-α/β and the expression of ISG15 protein in C3A cells
To investigate how HEV enhances the production of IFN-α/β and induces elevation of ISG15, we constructed a plasmid-expressing ORF3-EGFP (ORF3) and the HEV mutant leading to the loss of ORF3 protein expression (ΔORF3). C3A cells were transfected with ORF3 or ΔORF3 respectively, and the production of IFN-α/β and the expression of ISG15 protein were detected. The production of IFN-α/β was significantly increased at each time point in the group transfected with ORF3 plasmid (ORF3 group) compared to the ORF3-lacking group (ΔORF3 group) (P < 0.05). In addition, the detected by western blotting. The cells transfected with ISG15 plasmid had a considerably higher ISG15 level than the control cells ( Figure 4A). Then, the production of IFN-α/β was tested when cells were transfected with ISG15 plasmid and HEV RNA. The level of IFN-α/β was decreased when the cells were treated with HEV and ISG15 plasmid (P < 0.05) ( Figure 4B), which indicated over-expression of ISG15 may result in reduction of IFN-α/β.
DISCUSSION
The innate immune system is the first line of defense against invading pathogens. Type Ⅰ IFNs, such as IFN-α/ β, make up part of the innate immunity system and are critical for innate immunity against viral infection. ISG15, a member of the ISGs induced by IFN, has an important role in the regulation of antiviral immunity. In this study, we demonstrated that HEV infection could enhance the production of IFN-α/β and induce elevation of ISG15 protein. ORF3 protein may be responsible for the enhancement of IFN-α/β and ISG15 by HEV. Furthermore, ISG15 silencing enhanced the production of IFN-α/β in C3A cells. Over-expression of ISG15 resulted in the reduction of IFN-α/β in C3A cells. Collectively, these results indicated that HEV could induce the production of IFN and ISG15, and the increased ISG15 in turn reduced the level of IFN, which revealed a possible correlation between HEV infection and IFN production by regulating the expression of ISG15.
In our study, we first found that HEV infection could enhance the production of IFN-α/β and induce the elevation of ISG15 protein. A previous study demons-trated that most viruses have the ability to regulate the IFN response during infection [19] . When cells are infected by viruses, such as influenza viruses, the activated host innate immune response will lead to secretion of type Ⅰ IFN. Then, the induced IFN exerts its antiviral activity [20] . Over the last decade, numerous studies have reported that ISG15 plays a crucial role against viral infection [21,22] . However, few studies have investigated the effects of HEV on ISG15. In the present study, we found that the expression of ISG15 and the IFN level were simultaneously increased during HEV infection, which indicated that HEV could induce ISG15 expression in C3A cells. Recent studies have revealed that ISG15, as an innate immune protein with broad spectrum antiviral activity, continues to accumulate rapidly when the host is infected by a virus [23] , which is consistent with the findings in this research.
HEV consists of three ORFs. Genotype 1 HEV strain could inhibit type Ⅰ IFN induction by ORF1 products [24] .
However, the ORF3 products of genotype 1 HEV have been reported to enhance the production of IFN [25] . Because we found that genotype 3 HEV could induce the level of IFN, we next tested the impact of HEV ORF3 on IFN. We found that HEV ORF3 could increase the levels of IFN-α/β, which indicates that HEV ORF3 is responsible for the regulation of IFN. Similarly, we investigated whether HEV ORF3 could affect the expression of ISG15. As we expected, the level of ISG15 was increased by HEV ORF3. Previous studies have shown that ORF3 protein is associated with the egress of HEV [26] . As ISG15 is also associated with the process of egress for many RNA virus families [27] , we supposed that HEV ORF3 may regulate the egress of HEV through ISG15, which requires further experiments to confirm. Furthermore, the possible correlation between enhanced levels of IFN and ISG15 during HEV infection was investigated. ISG15 silencing enhanced the production of IFN-α/β, and over-expression of ISG15 resulted in the reduction of IFN-α/β in C3A cells, indicating that ISG15 is a negative regulator of IFN. It has been indicated that the absence of intracellular ISG15 in the ISG15-deficient patients prevents the accumulation of USP18, which is a potent negative regulator of IFN-α/β signaling, thus resulting in the enhancement and amplification of IFN-α/β responses and increase of viral resistance in humans [15,28] . In addition, it was found that ISG15 over-expression inhibited induction of IFN-β by HCV infection [29] . Evidence revealing high hepatic ISG15 levels was associated with low antiviral IFN-response during the early phase of antiviral therapy [30] , supporting the notion that ISG15 is a negative regulator of the IFN system. However, this raises the question of why the levels of IFN-α/β could be reduced by HEV infection via ISG15. As we know, the IFN production is always enhanced to promote an antiviral state in an infected host, but viruses have evolved many strategies to antagonize the induction of IFNs. As there is little knowledge about how HEV inhibits induction of IFN, the result that the level of IFN could be inhibited by HEV via ISG15 will enhance our fundamental knowledge of the mechanisms of induction and evasion of type Ⅰ IFN responses by HEV.
In conclusion, the findings of the present study showed that HEV could inhibit the level of type Ⅰ IFN through regulating the expression of ISG15, which may attenuate the IFN response, allowing for successful infection of the host. The present study enhances the understanding of the interaction between ISG15 and HEV in the host innate immune response, which may provide useful insight for the development of new antiviral drugs and antiviral strategies.
ARTICLE HIGHLIGHTS
Research background
Hepatitis E virus (HEV) infection is one of the most common causes of acute hepatitis or sporadic acute hepatitis in the world. At least 20 million HEV infections occur annually, which may result in chronic hepatitis in immunocompromised individuals. However, the mechanism of HEV pathogenesis remains obscure.
Research motivation
Over the last decade, numerous studies have reported that interferon (IFN)stimulated gene (ISG)15 plays a crucial role against viral infection. However, few studies have investigated the effects of HEV on ISG15.
Research objectives
In the present study, we investigated whether HEV infection could regulate the expression of ISG15 and the impact of ISG15 on IFN production during HEV infection, which is of great significance to expand our understanding of the interaction between ISG15 and HEV pathogenesis.
Research methods
In this study, C3A cells were first transfected with genotype 3 HEV RNA. The production of IFN-alpha and -beta (IFN-α/β) at different time points (0, 8, 12, 24, 48, 72 and 120 h) were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of ISG15 in HEV-infected C3A cells at different time points were tested by western blotting. Then, C3A cells were transfected with plasmid-expressing open reading frame 3 (ORF3) or control plasmids, the levels of IFN-α/β and ISG15 was evaluated, respectively. Next, the plasmidexpressing ISG15 or small interfering RNA-inhibiting ISG15 was transfected into infected C3A cells. The production of IFN-α/β was also measured by ELISA.
Research results
In this study, we demonstrated that HEV infection could enhance the production of IFN-α/β and induce elevation of the ISG15 protein. ORF3 protein may be responsible for the enhancement of IFN-α/β and ISG15 by HEV. Furthermore, ISG15 silencing enhanced the production of IFN-α/β in C3A cells. Overexpression of ISG15 resulted in the reduction of IFN-α/β in C3A cells.
Research conclusions
The findings of the present study showed that HEV could inhibit the level of type Ⅰ IFN through regulating the expression of ISG15, a finding which may enhance the understanding of the interaction between ISG15 and HEV in the host innate immune response, and provide useful insight for the development of new antiviral drugs and antiviral strategies.
Research perspectives
The future research will focus on whether HEV ORF3 could regulate the egress of HEV through ISG15.
To determine whether HEV infection could affect the production of type Ⅰ IFN, the concentrations of IFN-α/β were evaluated in cell culture supernatants at different time points (0, 8, 12, 24, 48, 72 and 120 h) by ELISA. The levels of IFN-α/β in the HEV infection group were significantly increased at each time point (P < 0.05), and the levels of IFN-α/β reached the maximum at 24 h, while no significant changes were observed in the control group (
Figure 1 Figure 3 Figure 2
132Hepatitis E virus infection enhances the production of Interferon-α and -β and induces elevation of Interferon-stimulated gene 15 protein in C3A cells. A: The concentrations of IFN-α and β were evaluated in cell culture supernatants at different time points (0, 8, 12, 24, 48, 72 and 120 h) by enzyme-linked immunosorbent assay; B: The expression of ISG15 protein replication was detected at different time points (0, 8, 12, 24, 48, 72 and 120 h) by western blotting. The data are expressed as mean ± standard error of the mean. a P < 0.05, b P < 0.01. HEV: Hepatitis E virus; IFN: Interferon; ISG: IFN-stimulated gene. Interferon-stimulated gene 15 silencing enhances the production of Interferon-α/β in C3A cells. Three siRNA inhibiting ISG15 (siISG15) and control-siRNA (si-control) were constructed, and C3A cells were cotransfected with 20 nmol/L ISG15-targeted siRNA (siISG15) or control-siRNA (si-control) along with HEV RNA. A: The mRNA level of ISG15 was estimated by reverse transcription-PCR; B: The protein level of ISG15 was estimated by western blotting. Next, the siRNA2 was transfected into C3A cells that had been pretreated with HEV RNA, and the impact of siISG15 on IFN was investigated; C: The level of IFN-α/β was tested by enzyme-linked immunosorbent assay. The data are expressed as mean ± standard error of the mean. a P < 0.05, b P < 0.01. HEV: Hepatitis E virus; IFN: Interferon; ISG: IFN-stimulated gene; si: Small interfering. Hepatitis E virus open reading frame 3 protein enhances the production of Interferon-α and β and the expression of Interferon-stimulated gene 15 protein in C3A cells. C3A cells were transfected with 2 μg of either pORF3-EGFP (ORF3) or pEGFP-N1 empty vector (GFP), and the HEV mutant, leading to the loss of ORF3 protein expression (ΔORF3) for 48 h, untreated cells were used as the control (Con). Then, the cells and cell culture supernatants were harvested at different time points (0, 8, 12, 24, 48, 72 and 120 h). A: The concentrations of IFN-α and β were evaluated in cell culture supernatants at different time points (0, 8, 12, 24, 48, 72, 120 h) by enzyme-linked immunosorbent assay; B: The expression of ISG15 protein was detected at different time points (0, 8, 12, 24, 48, 72 and 120 h) by western blotting. The data are expressed as mean ± standard error of the mean. a P < 0.05, b P < 0.01. GFP: Green fluorescent protein; HEV: Hepatitis E virus; IFN: Interferon; ISG: IFN-stimulated gene; ORF: Open reading frame.
Figure 4
4Over-expression of Interferon-stimulated gene 15 results in the reduction of Interferon-α/β in C3A cells. C3A cells were transfected with 2 mg ISG15-EGFP plasmid (ISG15) along with HEV RNA. A: ISG15 protein expression was detected by western blotting; B: The levels of IFN-α/β were detected by enzyme-linked immunosorbent assay. a P < 0.05. HEV: Hepatitis E virus; IFN: Interferon; ISG: IFN-stimulated gene.
Table 1
1Primers used in this studyWang M et al . HEV effects IFN production via ISG15
May 28, 2018|Volume 24|Issue 20| WJG|www.wjgnet.com
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. N Kamar, R Bendall, F Legrand-Abravanel, N S Xia, S Ijaz, J Izopet, Dalton Hr Hepatitis, E , 10.1016/S0140-6736(11)61849-7Lancet. 379Kamar N, Bendall R, Legrand-Abravanel F, Xia NS, Ijaz S, Izopet J, Dalton HR. Hepatitis E. Lancet 2012; 379: 2477-2488 [PMID: 22549046 DOI: 10.1016/S0140-6736(11)61849-7]
Hepatitis E: an emerging infection in developed countries. H R Dalton, R Bendall, S Ijaz, M Banks, 10.1016/S1473-3099(08)70255-X]Lancet Infect Dis. 8Dalton HR, Bendall R, Ijaz S, Banks M. Hepatitis E: an emerging infection in developed countries. Lancet Infect Dis 2008; 8: 698-709 [PMID: 18992406 DOI: 10.1016/S1473-3099(08)70255-X]
. J H Hoofnagle, K E Nelson, Purcell Rh Hepatitis, E , 23013075N Engl J Med. 367Hoofnagle JH, Nelson KE, Purcell RH. Hepatitis E. N Engl J Med 2012; 367: 1237-1244 [PMID: 23013075 DOI: 10.1056/ NEJMra1204512]
Hepatitis e and acute liver failure in pregnancy. Acharya Shalimar, Sk, 10.1016/j.jceh.2013.08.009J Clin Exp Hepatol. 3Shalimar, Acharya SK. Hepatitis e and acute liver failure in pregnancy. J Clin Exp Hepatol 2013; 3: 213-224 [PMID: 25755503 DOI: 10.1016/j.jceh.2013.08.009]
Persistent carriage of hepatitis E virus in patients with HIV infection. H R Dalton, R P Bendall, F E Keane, R S Tedder, S Ijaz, 19726781N Engl J Med. 361Dalton HR, Bendall RP, Keane FE, Tedder RS, Ijaz S. Persistent carriage of hepatitis E virus in patients with HIV infection. N Engl J Med 2009; 361: 1025-1027 [PMID: 19726781 DOI: 10.1056/ NEJMc0903778]
Factors associated with chronic hepatitis in patients with hepatitis E virus infection who have received solid organ transplants. N Kamar, C Garrouste, E B Haagsma, V Garrigue, S Pischke, C Chauvet, J Dumortier, A Cannesson, E Cassuto-Viguier, E Thervet, F Conti, P Lebray, H R Dalton, R Santella, N Kanaan, M Essig, C Mousson, S Radenne, A M Roque-Afonso, J Izopet, L Rostaing, 10.1053/j.gastro.2011.02.050Gastroenterology. 140Kamar N, Garrouste C, Haagsma EB, Garrigue V, Pischke S, Chauvet C, Dumortier J, Cannesson A, Cassuto-Viguier E, Thervet E, Conti F, Lebray P, Dalton HR, Santella R, Kanaan N, Essig M, Mousson C, Radenne S, Roque-Afonso AM, Izopet J, Rostaing L. Factors associated with chronic hepatitis in patients with hepatitis E virus infection who have received solid organ transplants. Gastroenterology 2011; 140: 1481-1489 [PMID: 21354150 DOI: 10.1053/j.gastro.2011.02.050]
Persistent hepatitis e virus genotype 4 infection in a child with acute lymphoblastic leukemia. Y Geng, H Zhang, W Huang, T Harrison, K Geng, Z Li, Y Wang, 10.5812/hepatmon.15618Hepat Mon. 1415618Geng Y, Zhang H, Huang W, J Harrison T, Geng K, Li Z, Wang Y. Persistent hepatitis e virus genotype 4 infection in a child with acute lymphoblastic leukemia. Hepat Mon 2014; 14: e15618 [PMID: 24596581 DOI: 10.5812/hepatmon.15618]
Hepatitis E virus infections in humans and animals. Y J Song, W J Park, B J Park, J B Lee, S Y Park, C S Song, N H Lee, K H Seo, Y S Kang, I S Choi, 10.7774/cevr.2014.3.1.29Clin Exp Vaccine Res. 3Song YJ, Park WJ, Park BJ, Lee JB, Park SY, Song CS, Lee NH, Seo KH, Kang YS, Choi IS. Hepatitis E virus infections in humans and animals. Clin Exp Vaccine Res 2014; 3: 29-36 [PMID: 24427760 DOI: 10.7774/cevr.2014.3.1.29]
Cross-species infections of cultured cells by hepatitis E virus and discovery of an infectious virus-host recombinant. P Shukla, H T Nguyen, U Torian, R E Engle, K Faulk, H R Dalton, R P Bendall, F E Keane, R H Purcell, S U Emerson, 10.1073/pnas.1018878108Proc Natl Acad Sci U S A. 108Shukla P, Nguyen HT, Torian U, Engle RE, Faulk K, Dalton HR, Bendall RP, Keane FE, Purcell RH, Emerson SU. Cross-species infections of cultured cells by hepatitis E virus and discovery of an infectious virus-host recombinant. Proc Natl Acad Sci U S A 2011; 108: 2438-2443 [PMID: 21262830 DOI: 10.1073/pnas.1018878108]
Characteristics and Functions of HEV Proteins. Y Zhou, C Zhao, Y Tian, N Xu, Y Wang, 10.1007/978-94-024-0942-0_2Adv Exp Med Biol. 948Zhou Y, Zhao C, Tian Y, Xu N, Wang Y. Characteristics and Functions of HEV Proteins. Adv Exp Med Biol 2016; 948: 17-38 [PMID: 27738977 DOI: 10.1007/978-94-024-0942-0_2]
Molecular virology of hepatitis E virus. I Ahmad, R P Holla, S Jameel, 21345356Virus Res. 161Ahmad I, Holla RP, Jameel S. Molecular virology of hepatitis E virus. Virus Res 2011; 161: 47-58 [PMID: 21345356 DOI: 10.1016/ j.virusres.2011.02.011]
Hepatitis E virus infection in immunosuppressed patients: natural history and therapy. N Kamar, L Rostaing, J Izopet, 23564390Semin Liver Dis. 33Kamar N, Rostaing L, Izopet J. Hepatitis E virus infection in immunosuppressed patients: natural history and therapy. Semin Liver Dis 2013; 33: 62-70 [PMID: 23564390 DOI: 10.1055/ s-0033-1338115]
Interferon-inducible antiviral effectors. A J Sadler, B R Williams, 18575461Nat Rev Immunol. 8Sadler AJ, Williams BR. Interferon-inducible antiviral effectors. Nat Rev Immunol 2008; 8: 559-568 [PMID: 18575461 DOI: 10.1038/ nri2314]
Functional classification of interferonstimulated genes identified using microarrays. M J De Veer, M Holko, M Frevel, E Walker, S Der, J M Paranjape, R H Silverman, B R Williams, 10.1189/jlb.1938-3673J Leukoc Biol. 69de Veer MJ, Holko M, Frevel M, Walker E, Der S, Paranjape JM, Silverman RH, Williams BR. Functional classification of interferon- stimulated genes identified using microarrays. J Leukoc Biol 2001; 69: 912-920 [PMID: 11404376 DOI: 10.1189/jlb.1938-3673]
Interferon-stimulated gene 15 and the protein ISGylation system. D Zhang, D E Zhang, 10.1089/jir.2010.0110J Interferon Cytokine Res. 31Zhang D, Zhang DE. Interferon-stimulated gene 15 and the protein ISGylation system. J Interferon Cytokine Res 2011; 31: 119-130 [PMID: 21190487 DOI: 10.1089/jir.2010.0110]
ISG15 conjugation system targets the viral NS1 protein in influenza A virus-infected cells. C Zhao, T Y Hsiang, R L Kuo, R M Krug, 10.1073/pnas.0909144107Proc Natl Acad Sci U S A. 107Zhao C, Hsiang TY, Kuo RL, Krug RM. ISG15 conjugation system targets the viral NS1 protein in influenza A virus-infected cells. Proc Natl Acad Sci U S A 2010; 107: 2253-2258 [PMID: 20133869 DOI: 10.1073/pnas.0909144107]
ISG15 Arg151 and the ISG15-conjugating enzyme UbE1L are important for innate immune control of Sindbis virus. N V Giannakopoulos, E Arutyunova, C Lai, D J Lenschow, A L Haas, H W Virgin, 10.1128/JVI.01590-08J Virol. 83Giannakopoulos NV, Arutyunova E, Lai C, Lenschow DJ, Haas AL, Virgin HW. ISG15 Arg151 and the ISG15-conjugating enzyme UbE1L are important for innate immune control of Sindbis virus. J Virol 2009; 83: 1602-1610 [PMID: 19073728 DOI: 10.1128/JVI.01590-08]
Innate antiviral response targets HIV-1 release by the induction of ubiquitin-like protein ISG15. A Okumura, G Lu, I Pitha-Rowe, P M Pitha, 10.1073/pnas.0510518103Proc Natl Acad Sci. 103Okumura A, Lu G, Pitha-Rowe I, Pitha PM. Innate antiviral response targets HIV-1 release by the induction of ubiquitin-like protein ISG15. Proc Natl Acad Sci USA 2006; 103: 1440-1445 [PMID: 16434471 DOI: 10.1073/pnas.0510518103]
Viruses and interferon: a fight for supremacy. M G Katze, Y He, M GaleJr, 10.1038/nri888Nat Rev Immunol. 2Katze MG, He Y, Gale M Jr. Viruses and interferon: a fight for supremacy. Nat Rev Immunol 2002; 2: 675-687 [PMID: 12209136 DOI: 10.1038/nri888]
Induction and evasion of type I interferon responses by influenza viruses. A García-Sastre, 10.1016/j.virusres.2011.10.017Virus Res. 162García-Sastre A. Induction and evasion of type I interferon responses by influenza viruses. Virus Res 2011; 162: 12-18 [PMID: 22027189 DOI: 10.1016/j.virusres.2011.10.017]
Emerging role of ISG15 in antiviral immunity. B Skaug, Z J Chen, 20946978Cell. 143Skaug B, Chen ZJ. Emerging role of ISG15 in antiviral immunity. Cell 2010; 143: 187-190 [PMID: 20946978 DOI: 10.1016/ j.cell.2010.09.033]
ISG15 and immune diseases. Y J Jeon, H M Yoo, C H Chung, 10.1016/j.bbadis.2010.02.006Biochim Biophys Acta. 1802Jeon YJ, Yoo HM, Chung CH. ISG15 and immune diseases. Biochim Biophys Acta 2010; 1802: 485-496 [PMID: 20153823 DOI: 10.1016/j.bbadis.2010.02.006]
Interferon-induced ISG15 pathway: an ongoing virus-host battle. C Zhao, M N Collins, T Y Hsiang, R M Krug, 10.1016/j.tim.2013.01.005Trends Microbiol. 21Zhao C, Collins MN, Hsiang TY, Krug RM. Interferon-induced ISG15 pathway: an ongoing virus-host battle. Trends Microbiol 2013; 21: 181-186 [PMID: 23414970 DOI: 10.1016/j.tim.2013.01.005]
Hepatitis E virus inhibits type I interferon induction by ORF1 products. Y Nan, Y Yu, Z Ma, S K Khattar, B Fredericksen, Y J Zhang, 25100852J Virol. 88Nan Y, Yu Y, Ma Z, Khattar SK, Fredericksen B, Zhang YJ. Hepatitis E virus inhibits type I interferon induction by ORF1 products. J Virol 2014; 88: 11924-11932 [PMID: 25100852 DOI: 10.1128/ JVI.01935-14]
Enhancement of interferon induction by ORF3 product of hepatitis E virus. Y Nan, Z Ma, R Wang, Y Yu, H Kannan, B Fredericksen, Y J Zhang, 10.1128/JVI.01228-14J Virol. 88Nan Y, Ma Z, Wang R, Yu Y, Kannan H, Fredericksen B, Zhang YJ. Enhancement of interferon induction by ORF3 product of hepatitis E virus. J Virol 2014; 88: 8696-8705 [PMID: 24850742 DOI: 10.1128/JVI.01228-14]
A PSAP motif in the ORF3 protein of hepatitis E virus is necessary for virion release from infected cells. S Nagashima, M Takahashi, Jirintai, T Tanaka, K Yamada, T Nishizawa, H Okamoto, 10.1099/vir.0.025791-0J Gen Virol. 92Nagashima S, Takahashi M, Jirintai, Tanaka T, Yamada K, Nishizawa T, Okamoto H. A PSAP motif in the ORF3 protein of hepatitis E virus is necessary for virion release from infected cells. J Gen Virol 2011; 92: 269-278 [PMID: 21068219 DOI: 10.1099/vir.0.025791-0]
Mechanisms for enveloped virus budding: can some viruses do without an ESCRT?. B J Chen, R A Lamb, 10.1016/j.virol.2007.11.008Virology. 372Chen BJ, Lamb RA. Mechanisms for enveloped virus budding: can some viruses do without an ESCRT? Virology 2008; 372: 221-232 [PMID: 18063004 DOI: 10.1016/j.virol.2007.11.008]
Human intracellular ISG15 prevents interferon-α/β over-amplification and auto-inflammation. X Zhang, D Bogunovic, B Payelle-Brogard, V Francois-Newton, S D Speer, C Yuan, S Volpi, Z Li, O Sanal, D Mansouri, I Tezcan, G I Rice, C Chen, N Mansouri, S A Mahdaviani, Y Itan, B Boisson, S Okada, L Zeng, X Wang, H Jiang, W Liu, T Han, D Liu, T Ma, B Wang, M Liu, J Y Liu, Q K Wang, D Yalnizoglu, L Radoshevich, G Uzé, P Gros, F Rozenberg, S Y Zhang, E Jouanguy, J Bustamante, A García-Sastre, L Abel, P Lebon, L D Notarangelo, Y J Crow, S Boisson-Dupuis, J L Casanova, S Pellegrini, 10.1038/nature13801Nature. 517Zhang X, Bogunovic D, Payelle-Brogard B, Francois-Newton V, Speer SD, Yuan C, Volpi S, Li Z, Sanal O, Mansouri D, Tezcan I, Rice GI, Chen C, Mansouri N, Mahdaviani SA, Itan Y, Boisson B, Okada S, Zeng L, Wang X, Jiang H, Liu W, Han T, Liu D, Ma T, Wang B, Liu M, Liu JY, Wang QK, Yalnizoglu D, Radoshevich L, Uzé G, Gros P, Rozenberg F, Zhang SY, Jouanguy E, Bustamante J, García-Sastre A, Abel L, Lebon P, Notarangelo LD, Crow YJ, Boisson-Dupuis S, Casanova JL, Pellegrini S. Human intracellular ISG15 prevents interferon-α/β over-amplification and auto-inflammation. Nature 2015; 517: 89-93 [PMID: 25307056 DOI: 10.1038/nature13801]
Hepatitis C virus reveals a novel early control in acute immune response. N Arnaud, S Dabo, D Akazawa, M Fukasawa, F Shinkai-Ouchi, J Hugon, T Wakita, E F Meurs, 10.1371/journal.ppat.1002289PLoS Pathog. 71002289Arnaud N, Dabo S, Akazawa D, Fukasawa M, Shinkai-Ouchi F, Hugon J, Wakita T, Meurs EF. Hepatitis C virus reveals a novel early control in acute immune response. PLoS Pathog 2011; 7: e1002289 [PMID: 22022264 DOI: 10.1371/journal.ppat.1002289]
The interferon stimulated gene 15 functions as a proviral factor for the hepatitis C virus and as a regulator of the IFN response. R Broering, X Zhang, S Kottilil, M Trippler, M Jiang, M Lu, G Gerken, J F Schlaak, 10.1136/gut.2009.195545Gut. 59Broering R, Zhang X, Kottilil S, Trippler M, Jiang M, Lu M, Gerken G, Schlaak JF. The interferon stimulated gene 15 functions as a proviral factor for the hepatitis C virus and as a regulator of the IFN response. Gut 2010; 59: 1111-1119 [PMID: 20639253 DOI: 10.1136/gut.2009.195545]
. P-Reviewer: Domagalski, K Ierardi, E Inoue, K Tomizawa, M S-Editor , Gou ZM L-Editor: Filipodia E-Editor: Yin SYP-Reviewer: Domagalski K, Ierardi E, Inoue K, Tomizawa M S-Editor: Gou ZM L-Editor: Filipodia E-Editor: Yin SY
| 1,999,708 | Chronic viral infections, such as chronic hepatitis C, are major causes of disease worldwide. They represent model systems for the study both of sophisticated ways to elute host defense mechanisms, and of mechanisms to sustain inflammation, potentially leading to autoimmune manifestations as a side effect. Cytokines are central inducers and regulators of both immune-mediated virus clearance and of immunopathology. This review describes the potential implications of TNFa in the development and clinical progression of chronic hepatitis C infection. The frequency of chronic hepatitis C, its usually indolent course, and the current application of these biological agents for the management of continuously expanding therapeutic indices, renders the study of the molecular effects and safety of TNFa antagonists in chronic HCV carriers of particular clinical significance. | Quantitation of hepatitis C virus in liver and peripheral blood mononuclear cells from patients with chronic hepatitis C virus infection | AIM: Mechanisms responsible for persistence of HCV infection and liver damage in chronic hepatitis C are not clear. Apoptosis is an important form of host immune response against viral infections. Anti-apoptotic proteinbcl-2 expression on liver tissue as well as the influence of interferon alpha 2b (IFNα2b) and ribavirin (RBV) were analyzed in patients with chronic hepatitis C. METHODS: In 30 patients with chronic hepatitis C (responders - R and non-responders - NR) treated with IFNα2b+RBV, protein bcl-2 was determined in hepatocytes and in liver associated lymphocytes before and after the treatment.RESULTS: The treatment diminished bcl-2 protein accumulation in liver cells in_patients with hepatitis C (P＜0.05). Before and after the therapy, we detected bcl-2 protein in R in 87±15% and 83±20% of hepatocytes andin 28± 18% and 26±10% of liver-associated lymphocytes, respectively. In NR, the values before treatment decreased from 94±32% to 88±21% of hepatocytes and 39±29% to 28±12% of lymphocytes with bcl-2 expression. There was no statistical correlation between bcl-2 expression on liver tissue with inflammatory activity, fibrosis and biochemical parameters before and after the treatment.CONCLUSION: IFNα2b+RBV treatment, by bcl-2 protein expression decrease, enables apoptosis of hepatocytes and associated liver lymphocytes, which in turn eliminate hepatitis C viruses. | Hepatitis C virus, a small single-stranded RNA virus, is a major cause of chronic liver disease. Resolution of primary hepatitis C virus infections depends upon the vigorous responses of CD4+ and CD8+ T cells to multiple viral epitopes. Although such broad CD4+ and CD8+ T-cell responses are readily detected early during the course of infection regardless of clinical outcome, they are not maintained in individuals who develop chronic disease. Purportedly, a variety of factors contribute to the diminished T-cell responses observed in chronic, virus-infected patients including the induction of and biological suppression by CD4+FoxP3+ regulatory T cells. Indeed, a wealth of evidence suggests that regulatory T cells play diverse roles in the pathogenesis of chronic hepatitis C, impairing the effector T-cell response and viral clearance early during the course of infection and suppressing liver injury as the disease progresses. The factors that affect the generation and biological response of regulatory T cells in chronic, hepatitis C virus-infected patients is discussed. | Cytokine Profiles and Hepatic Injury in Occult Hepatitis C Versus Chronic Hepatitis C Virus Infection | Expression of endocrine autoantibodies in chronic hepatitis C, before and after interferon-alpha therapy. | Epidemiological, immunological and virological aspects of acute and chronic hepatitis C virus infections | Abstract Increased infiltration of lymphocytes and induction of damage and destruction of hepatocytes by these lymphocytes are characteristic features of chronic viral hepatitis. As chemokines attract lymphocytes to inflamed tissues, we studied macrophage inflammatory protein (MIP)-3alpha, a CC chemokine, in chronic viral hepatitis. The levels of MIP-3alpha were measured in the sera from 40 patients with chronic viral hepatitis and 30 control subjects by an enzyme-linked immunosorbent assay (detection limit of MIP-3alpha=7.8 pg/mL). The kinetics of MIP-3alpha were checked during interferon (IFN) therapy in 25 patients. The levels of MIP-3alpha in the sera were significantly higher in patients with chronic viral hepatitis (39.0 +/- 28.9 pg/mL) than control subjects (15.6 +/- 4.9 pg/mL; P < 0.0001) and in patients with severe (49.6 +/- 49.2 pg/mL) and moderate degree of hepatitis (50.9 +/- 27.1 pg/mL) than in mild disease (16.0 +/- 6.8 pg/mL; P < 0.05). A significant correlation was seen among serum MIP-3alpha levels with the levels of alanine aminotransferase (r=0.509, P < 0.0001), aspartate aminotransferase (r=0.505, P < 0.0001), and degrees of activity of hepatitis (r=0.592, P < 0.0001) and interface hepatitis (r=0.419, P=0.0066). The levels of MIP-3alpha were significantly increased in patients with hepatitis C 2 weeks after the start of therapy in IFN-responders, but, remained almost unchanged in IFN-nonresponders. These findings might be important not only for the understanding of immunoptahogenesis of hepatocellular damage in chronic hepatitis (CH) patients but also for a therapeutic strategy to control the local immune response in the liver. A prognostic value of MIP-3alpha during IFN therapy in patients with chronic hepatitis C is also shown. | Tumour necrosis factor and Interleukine 6 in patient with Hepatitis C virus |
1,999,709 | How do you measure your legs for half chaps? | I have to take some photos' soon and I want my legs to look good. | How do they measure mountain heighth? | Intraobserver and Interobserver Agreements of Leg Circumference Measurements by Tape Measure Based on 3 Reference Points | Measuring easily performed by a Two-foot Rule which slides to a Foot." By 1767, seven revised editions had been released. Coggeshall slide rule In measurement, the Coggeshall slide rule, also called a carpenter's slide rule, was a slide rule designed by Henry Coggeshall in 1677 to help in measuring the dimensions, surface area, and volume of timber. With his original design and later improvements, Coggeshall's slide rule brought the tool its first practical use outside of mathematical study. It would remain popular for the next few centuries. The Coggeshall rule consisted of two rulers, each a foot (30 cm) long, | Legs a little too long but will have shortened. Great warmth for coming winter. | How do they measure height in europe? | I have installed the latest HF patch and it feels like it's lacking in legwear/thigh highs mod. There are some that I have that was already included, but none at the height of e.g. Tohsaka Rin kind of thigh highs. So do you know if I can get more from somewhere? | A foot needed for quilting. Does make life easier to get that perfect 1/4 inch seam line without having to eyeball it. | 1,999,709 | Where are half chaps made? | where are chausson motorhomes made? | where did the chauhan originates from | Who invented Cha-cha-cha? | Where was the chavin located? | when was the first post chaise made | where is the chafariz doscontos located in brazil indiana | where was made this item? | where are dainese leathers made? |
1,999,710 | who was the court gardener who designed the albrechtsberg palace | Albrechtsberg Palace (Dresden) by order of the Prince for 16,000 Thalers. Adolf Lohse, a student of Karl Friedrich Schinkel, designed the plans for the present-day castle. For the gardens, the Prince engaged the Prussian landscape architect Eduard Neide (1818–1883) who created the plan, though the court gardener Hermann Sigismund Neumann (1829–1880) accomplished them. Before Albrechtsberg, the adjacent Villa Stockhausen was completed. The villa was originally established for the chamberlain, but was used for the first year as domicile of the Prince and his wife. 1854 the castle was accomplished and the couple moved in. After Prince Albrecht and Rosalie had died, their younger | Ludwigsburg Palace Ludwigsburg Palace (Residenzschloss Ludwigsburg), also known as the "Versailles of Swabia", is a 452-room palace complex of 18 buildings located in Ludwigsburg, Baden-Württemberg, Germany. With the gardens, its total area is — the largest palatial estate in the country. The palace has four wings; the northern wing, the Alter Hauptbau, is the oldest and was used as a ducal residence. The east and west wings were used for court purposes and housing guests and courtiers. The southern wing, the Neuer Hauptbau, was built to house more court functions and was later used as a residence. Eberhard Louis, Duke | state of Hesse until 1945. It is due to its past as a capital city that it has many architectural testimonies of this period. Many of its major architectural landmarks were created by Georg Moller who was appointed the court master builder of the Grand Duchy of Hesse. Due to the fact that the last ruling Grand Duke of Hesse, Ernst Ludwig was a grandson of Queen Victoria and brother to Empress Alexandra of Russia, the architecture of Darmstadt has been influenced by British and Russian imperial architecture with many examples still existing, such as the Luisenplatz with its grand-ducal | Karlsberg Castle Karlsberg Castle () is a castle ruin on Buchenberg east of Homburg in Saarland, Germany. The castle was constructed from 1778 to 1788 in Baroque and Classical style by Johann Christian von Mannlich, architect and general building director of the dukes of Zweibrücken, by order of Charles II August, Duke of Zweibrücken. The castle was the largest country palace of Europe and served as the residence of the Duke of Zweibrücken. In 1793 the castle was destroyed by French revolutionary troops. Charles II August was the son of the (titular) Count Palatine and prince of Palatinate-Zweibrücken and Palatinate-Birkenfeld-Bischweiler | Court chapel, or its equivalent in other languages (like Hofkapelle in German), may refer to:
Buildings
Mannheim Palace Church, founded as a court chapel
Opernhaus am Taschenberg (sometimes indicated as "Hofkapelle"), which served as the Catholic Hofkirche (court church) in Dresden from 1708 to 1751
Tottenham Court Chapel, a.k.a. Whitefield's Tabernacle, Tottenham Court Road, UK
Hofkapelle of Schloss Weimar, in Weimar, Thuringia, Germany
Hofkapelle of the Hofburg Palace, Vienna
Hofkapelle of the Würzburg Residence, in Würzburg, Lower Franconia, Germany
Musical ensembles
Flemish chapel (capilla flamenca), associated with the Spanish imperial court
Hannoversche Hofkapelle, a court orchestra in Hannover, Germany
Saint Petersburg Court Chapel, Russian imperial court chapel
Hofkapelle Stuttgart, a German orchestra based in Stuttgart
See also
Royal chapel (disambiguation)
Staatskapelle (disambiguation) | Augustusburg and Falkenlust Palaces, Brühl Augustusburg and Falkenlust Palaces, Brühl The Augustusburg and Falkenlust Palaces form a historical building complex in Brühl, North Rhine-Westphalia, Germany, which has been listed as a UNESCO cultural World Heritage Site since 1984. The buildings are connected by the spacious gardens and trees of the Schlosspark. Augustusburg Palace () and its parks also serve as a venue for the Brühl Palace Concerts. The Max Ernst Museum is located nearby. The palaces were built at the beginning of the 18th century by the Archbishop-Elector of Cologne, Clemens August of Bavaria of the Wittelsbach family. The architects were Johann Conrad Schlaun and | the Court Chapel was housed in the former Opernhaus am Taschenberg, as a public church, until the construction of the new Hofkirche ("court church") was finished in 1751. The Mannheim Palace Church was the Old Catholic court chapel for the prince-electors of the Electorate of the Palatinate between 1731 and 1777. Best known composer of the court chapel is Johann Stamitz, founder of the Mannheim school around 1750. The Munich court chapel was arguably the most splendid one of the second half of the 16th century, and played an important role in the European music life of its day. Orlandus | A brief description of the erlangen court theatre built by the margraves of brandenburg-bayreuth (today, bavaria): its 18th century exterior structures were replaced by modern ones in 1959; the interior setting and decoration were renovated, restored and de-restored in 1892/93, in the 1950s and the 1980s. 4 photographs, bibliographic references. | 1,999,710 | Albrechtsberg Palace (Dresden) the composition was the style of the classicism. For this style, especially important is the Grecian and Roman antiquity; the Italian Renaissance and its traditionally application. The guide for the composition of the castle was the Ville d'Este close to Rome. For the creation of the park, the Prussia garden architect Eduard Neide 1818-1883 was engaged. However, the court gardener Hermann Sigismund Neumann carried them out. Under the management of the court gardener, four landscapes were created. Those were crossed by curved alleys that are go over bridges and a viaduct. These alleys passe applied ponds, rocks and a waterfall. | who runs the botanical garden in dresden germany | when was augustusburg and falkenlust palace listed as a world heritage | who designed the garden in the louvre palace | who designed the neoclassical palace in pławowice | the palace of europe is in which city | who designed the german pavilion for the 1936 olympics | what is the name of the palace in mecklenburg germany | who sculpted the grotto in the courtyard of the palace |
1,999,711 | [Ofrecido] IOT y Sistemas Industriales | Taking the cotton manufacturing as an example,the necessity and possibility to build the internet of things in textile mills are proved by practical investigations and application researches.The aim is at energy save and emission reduction as well as reduction of equipment maintaining cost and operation safety.The design of equipment monitoring and data acquisition based on the internet of thing s are also given. | The mechanism design of the IOT industry is the key to the industrialization of IOT, which is worthy of study due to its practical significance. Considering IOT industry of Jiangsu, the paper makes a systematical research on its cultivation mechanism design from the perspective of market cultivation, technology cultivation and policy support. And the framework of mechanism design of the IOT industry of Jiangsu can be interpreted from the dimensions of industrial attributes, cultivating principles and cultivating contents. Finally,suggestions for the market cultivation mechanism design, technology cultivation mechanism and policy supporting system of IOT industry of Jiangsu are proposed, which contribute to the development of IOT industry of Jiangsu. | This paper describes the potential impact of the Internet of Things (IoT) technologies and architecture on factory automation. Whereas, IoT use cases range from intelligent infrastructure and smart cities to health care and shopping assistants, it is important to note that factory automation could benefit as well from an IoT approach. In this paper, we argue that there will not be one IoT but many IoTs that could differ in the type of infrastructure they are running or applications they support. In IoT@Work we focus on the potential of making manufacturing environments more agile and flexible. We explain how the IoT-centric architecture for manufacturing also needs a deep understanding of the manufacturing system and its state today. We, therefore, do a reverse engineering based on the requirements and the description of the agility expected in the automation system itself. | industrial subset of the IoT. The industrial internet of things will enable the creation of new business models by improving productivity, exploiting analytics for innovation, and transforming the workforce. The potential of growth by implementing IIoT is predicted to generate $15 trillion of global GDP by 2030. While connectivity and data acquisition are imperative for IIoT, they are not the end goals, but rather the foundation and path to something bigger. Of all the technologies, predictive maintenance is an "easier” application, as it is applicable to existing assets and management systems. Intelligent maintenance systems can reduce unexpected downtime and increase | Servicing the factory of the future raises challenges for the service teams and organizations. The industrial plant environment is changing rapidly due to the impact of the market and new autonomously operating information technologies such as on site information and communication services, an Internet of Things (IoT), smart sensors and intelligent automation devices as well as progress in conventional machines and technologies. |
I. INTRODUCTION
Internet of things (IoT) has recently induced as a topic of intense interest among the research community since it integrates various technologies. The main concept of IoT is that various devices comprising different technologies will be connected and communicating with each other without human intervention. IoT is a communication paradigm that gives the concept of communication between the objects of our daily life, connected over the internet. IoT has gained the capability of interacting with a wide variety of devices such as household appliances, industrial machines, robots, drones, power generation systems and many others. By controlling and managing a massive amount of data, produced by such devices, IoT can provide new services to luxuriate human life.
[© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.] In the current era, security is the major concern of IoT [1]. Firewalls, intrusion detection systems (IDS) and intrusion prevention systems (IPS) are the major security shields to protect the devices and network from cyber-attacks. Most of the firewalls, IDS and IPS filter the normal and malicious traffic based upon the signatures, i.e., static predefined rules. While a few IDS and IPS use artificial intelligence (AI) techniques along with signatures to detect the attack traffic. The IDS and IPS that filter the intrusive attempts using both signatures and AI techniques are more effective as compared to those which only use signatures. The AI-based IDS and IPS are trained and tested using normal and attack traffic datasets. These datasets are collected by two approaches, i.e., either by using real systems to generate malicious and normal network traffic or by using some traffic generator tools which mimic the real-time network traffic.
No matter, the present IDS and IPS technology is quite mature but it is inadequate for IoT Systems [2]. The primary cause is the communication protocols like CoAP, MQTT, etc., which IoT devices use, are not employed in a traditional network as different protocols carry different vulnerabilities and requirements [2]. Another crucial factor is the limited processing and storage capacity of the IoT devices due to which host-based IDS cannot be installed on IoT devices. However, the network-based IDS can protect the IoT network and devices from cyber-attacks if they are equipped with the support of IoT protocols.
There exist some datasets like KDD-99 [3], NSL-KDD [4], CAIDA [5], ISCX [6], etc., that are widely used for developing the security systems to protect the IoT networks from malicious attacks. However, these datasets have certain issues with respect to IoT, like these datasets don't have the traffic of commonly used IoT protocols, e.g., MQTT, CoAP, etc. Moreover, some of these datasets are so old that they are outdated, as there is a quite difference between the past and current cyber-attacks [7]. Nevertheless, this dilemma can be untangled by generating the dataset through a network traffic generator tool which can generate both normal and attack traffic of commonly used IoT protocols.
A network traffic generator tool is a kind of software that allows a user to generate the detailed custom packets. The traffic generator tools are extensively used by researchers and secu-rity providers in order to develop and test security applications like IDS, IPS, etc. Moreover, it can be used for the evaluation of network performance like stress testing [8]. Furthermore, network engineers use traffic generator tools for benchmarking the network features and to troubleshoot the network problems. So far, many traffic generator tools/frameworks have been proposed [9]- [13] by both the research and software development community. However, these frameworks/tools have certain shortcomings like IoT application layer protocols support is still missing in these tools. Similarly, most of the traffic generating tools lack of generating the attack traffic. Hence, the existing traffic generator tools/frameworks are inadequate for developing and testing the security solutions of the IoT networks. Therefore, we proposed a framework for IoT traffic generation which can generate both the normal and attack traffic of two widely used IoT application layer protocols, i.e., MQTT and CoAP.
The main focus of this work is to propose a framework which consists of an IoT traffic generator tool so that the researchers may easily build their own use case, model IoT devices into it and then generate & analyse the traffic of the use case in order to develop better security solutions for IoT. The proposed traffic generation framework can also be used in stress testing of different IoT-based network utilities like switches, routers, etc., by generating a large amount of IoT device traffic. Moreover, it can also be used for the designing and testing of IoT security providing entities like IDS, IPS, etc. The key contributions of this work are as follows: • We proposed an open-source framework which consists of an IoT traffic generator tool which is capable of generating IoT normal and attack traffic over a real-time network using a single physical machine. • To our best knowledge, we are the first to design an open-source IoT traffic generator which supports two application layer IoT protocols, i.e., MQTT and CoAP. • We devised IoT device modelling by introducing the concept of time profile and data profile in order to better emulate the IoT devices. • Furthermore, we implemented a real-time smart home use case using the proposed IoT traffic generation framework and demonstrated how the generated traffic can be used to develop a machine learning based security solution. The rest of the paper is structured as follows: Section II presents a review of some existing traffic generator tools/frameworks. Section III describes the features, architecture and working of the proposed framework. Section IV discusses the experimentation and demonstrates how IoT traffic can be generated and used for developing machine learning based security solutions. Lastly, Section V concludes the paper.
II. RELATED WORK
The network traffic generator tools are used extensively for evaluation of network performance like throughput calculation, stress testing [8], etc. So far, many traffic generator tools have been proposed in the literature. In [14], authors proposed a traffic generator tool for switch testing. The developed traffic generator consists of both hardware and software modules. The software module generates configurations and parameters according to the traffic model selected by the user. While the hardware module generates the packets as specified by the software module and send it to the network interface module. In [11], authors introduced a scriptable traffic generator which consists of both hardware and software modules. The software module was developed for packet configurations while the hardware module was developed to control the packets rate and latency. However, it can only generate ICMP, ARP, TCP, UDP and IP protocols traffic.
In [8], authors proposed a traffic generation framework for testing the deep packet inspection (DPI) tools. The proposed framework generates network traffic based on user behaviour emulation. They gathered the real-time traffic, analyzed it and extracted the typical user behaviour to emulate it later for testing the DPI tools. In [12], authors designed a hardware IoT device which can generate the IoT traffic. The designed hardware can generate traffic flows simultaneously based on the interval length and data size. However, this device only generates layer 2 traffic. While in case of IoT, we are primarily concerned with application layer protocols like MQTT, CoAP, HTTP etc. In [15], authors proposed a traffic generator framework by integrating the machine type communication (MTC) traffic models with big data. The framework was proposed to evaluate the performance of mobile networks.
In [13], authors designed a tool that not only generates the network traffic but also evaluates the network performance as well as functional testing at the switch level. The tool can be used to generate different test scenarios and analyze the response in order to check the functional aspects of the switch network. In [16], authors proposed a traffic generator which can generate the network traffic of the network layer and transport layer. The traffic generator supports TCP and UDP protocols. A user has to specify the content, data size, duration, flow features and traffic model in order to generate the traffic.
In addition to the literature, many open-source traffic generator tools are developed by the software development community. For example, Packet Sender [9] is an open-source tool that supports sending and receiving TCP, UDP and SSL traffic in order to test network APIs and network connectivity. Likewise, D-ITG tool [10] emulates the network traffic of TCP, UDP, ICMP protocols. Moreover, it also measures the network performance metrics like throughput, delay, losses, etc., based upon the network flows.
Although, many traffic generator tools/frameworks have been developed by both the research and software development community IoT application layer protocols support is still missing. Furthermore, a large number of network traffic generator tools do not generate the attack traffic. Hence, the existing traffic generator tools are inadequate for testing the performance and security of the IoT networks. Therefore, we proposed a novel open-source framework which consists of a traffic generator tool. The proposed framework can generate
III. PROPOSED FRAMEWORK
The proposed framework consists of an open-source IoT traffic generator tool which can generate the normal and attack traffic of IoT devices over a real-time network. We named it as IoT-Flock. Fig. 1 shows layer-wise core functionalities of the IoT-Flock. The IoT-Flock has following distinct features as compared to other commercially or publicly available traffic generator tools:
• IoT-Flock has two working modes, i.e., GUI mode and console mode which allows a user to create real-time IoT use cases add thousands of IoT devices into the use case. • IoT-Flock provides XML support to import or export the designed use case. Thus, a user can create, share and run a use case through an XML file. • IoT-Flock can also generate MQTT and CoAP related attacks. To our best knowledge, this feature is not supported yet by any other open-source IoT traffic generator tool. Thus, a user can easily create both normal and attacking devices in the same use case and generate their traffic.
A. IoT-Flock Architecture
We followed layered architecture in order to develop the IoT-Flock. IoT-Flock comprises of three layers, i.e., presentation layer, business logic layer and network layer. The following subsections describe these layers.
1) Presentation Layer:
The presentation layer is responsible for viewing the interface to the end-user. It works in two modes, i.e., console mode and graphical user interface (GUI) mode. In console mode, a user will import the use case XML file through the console and run the tool for generating the IoT traffic as defined in the XML file. In GUI mode, a user will first create an IoT use case then add different IoT devices into it. A user can add MQTT and CoAP devices into the use case. While creating a device, a user has to give the information about the device name, device IP address, device type, number of devices and protocol type in order to emulate the device traffic over the real-time network using IoT-Flock.
If a user selects MQTT protocol, then the MQTT GUI form will be enabled and the user has to give the further device information of MQTT device. In order to emulate an MQTT device, a user has to mention MQTT broker IP & port, username & password of the MQTT broker if exists and MQTT device type, i.e., subscriber or publisher.
If the device is a subscriber, then the user must mention the topic name which the device needs to be subscribed. For this purpose, a user can either select a topic from the topic list which the user has already saved or he/she may add a new topic if the topic name does not exist the topic list.
If the device is a publisher, then the user must mention the topic name along with the time profile and data profile in order to emulate the device behaviour.
-For the time profile, a user must tell in which frequency a device publishes the data, i.e., whether a device sends data after some specific interval (i.e., periodically, randomly, etc.) or after the occurrence of some event.
-For the data profile, a user must tell what type of data the device will is published by IoT device? It may be a numeric or binary or String data. Moreover, the user must define the data values or range of values that the device can publish in real-time in order to emulate the publishing device.
Both the time profile and data profile can be saved in the database so that they may be used later if some other device has the same time or data profile.
Likewise, if a user selects CoAP protocol from the main window, then the CoAP related GUI will be enabled and the user has to give information about CoAP server IP & port, CoAP method, time profile and data profile. The CoAP method includes four options, i.e., GET, POST, PUT and UPDATE which are briefly described in Table I. 2) Business Logic Layer: The business logic layer is responsible for implementing the user requirements that have been gathered from the presentation layer. We used four opensource APIs and database management system (DBMS) to implement the user required functionalities which include MQTT API [17], CoAP API [18] and libtins API [19]. The MQTT API [17] is used to create MQTT publisher and MQTT subscriber devices. An MQTT subscriber device will first send the subscribe request to the MQTT broker against some topic to establish the connection with MQTT broker and then will receive messages when some IoT device will publish a Similarly, an MQTT publisher device will first establish a connection with MQTT broker then will publish the message to the MQTT broker using MQTT API [17]. Likewise, the CoAP API [18] is used to send the user request to the CoAP server. The libtins API [19] is used to generate an attacking device. Finally, SQL DBMS is used to store the use case related information.
3) Network Layer: The network interface layer is responsible for assigning a unique virtual IP to each IoT device from a single physical system. Moreover, it is also responsible for sending and receiving the data to/from the network.
B. IoT-Flock Working
The flow diagram shown in Fig. 2(a) illustrates the working of IoT-Flock. It consists of four steps: create use case, add IoT devices to use case, save XML and run the use case & generate IoT traffic. Upon starting the IoT-Flock in GUI mode, a user will first create the desired use case by simply clicking at '+ new use case' button. After entering the use case name, the user will click on 'OK' to create the use case and the use case window will appear. Now the user has to add IoT devices into the use case. Fig. 2(b) shows the device creation steps. A user can create both IoT normal and attack device with respect to use case. After adding the devices, the next step is to generate an XML file of the use case. In case, if a user needs to re-run the use case after some time, then a user can simply load and run the saved XML file of the use case instead of re-creating it. Moreover, the generated XML file can be shared with anyone to ease him/her in understanding the use case. Lastly, the user will click on the 'Start' button to initiate the emulation of the use case.
C. Attack Types in IoT-Flock
Currently, we included four recent IoT application layer vulnerability attacks in the IoT-Flock. However, one can add more types of attacks in IoT-Flock by extending the source code. These attacks are reported recently in a well-known vulnerability reporting platform, i.e., national vulnerability database (NVD) [20]. Below is the description of these attacks.
MQTT Packet Crafting Attack -In this attack, MQTT packets are specially crafted to crash an application. The attacker first establishes a connection with MQTT broker at Transport layer and then sends the MQTT publish command right at the beginning instead of sending a connection request to MQTT broker [21].
MQTT Publish Flood -IoT devices follow a periodic or event-driven model for sending data using application layer protocols. In the periodic model, the device is set to send data after every x interval, e.g., temperature sensor sends temperature data after every five seconds to the server and in event-driven model device send data when some event occurs e.g motion sensor is configured to only send data to the server when it detects motion in the environment. According to [22], MQTT publishing message at a high rate can cause a denial of service (DoS) attack. CoAP Segmentation Fault Attack -While communicating with the CoAP server, a valid Uri-Path is an essential part of the request and response packet. Recently, an attack is reported in which the attacker when sets the Uri-Path as null, then CoAP server mishandles such packets hence causes the segmentation fault [23]. Moreover, an attacker can generate the DoS attack by sending such packets in a large amount.
CoAP Memory Leak Attack -CoAP server sends or receives data based upon the CoAP methods as called by the clients. It is reported that when an attacker sends invalid options to the CoAP server, it causes the memory crash as the processing of packet with single invalid option wastes 24 bytes of memory [24].
IV. EXPERIMENTAL ANALYSIS
A. Experimental Setup 1) Use Case Creation & Traffic Generation:
A real-time IoT smart home system is deployed in our laboratory and office environment. In our smart home use case ten IoT devices are installed. Each device contains four types of environment monitoring sensors, i.e., temperature sensor, humidity sensor, motion sensor and light sensor. All the devices and sensors communicate over MQTT protocol within a wireless local area network (WLAN) environment. All the sensors except the motion sensors are set to send the data periodically to the server after every 3 minutes where this received data is saved into a database. The motion sensor sends data to the server only when it detects motion. The data saved in the server database is read by a rule engine which controls the switching of home appliances based on the conditions as defined by the user. In our case, the rule engine is controlling three types of appliances which includes air conditioners (AC), lights and fans.
To implement the above discussed real-time use case into IoT-Flock, we first analyzed the traffic patterns of the real-time devices as shown in Table II. For time profile, we observed that all sensors except the motion sensor are sending data periodically, i.e., after every 180s. So, we set their time profile as periodic at 180s and set data profile using (1):
Data Range = (MIN [Average V alue, Mode V alue], MAX[Average V alue, Mode V alue]) (1)
For motion sensor, we set it to send 1 and 0 randomly between time range 3s to 5s. Once we finalized the time profile and data profile of the smart home use case as shown in Table III, next we created a use case in IoT-Flock and named it as 'Smart
Home' by following the steps shown in Fig. 2 2) Data Capturing: After creating both the normal and attack networks, we first started the normal network to generate IoT normal traffic. After 10 minutes, we started the attack network. The whole emulation ran for 30 minutes and we captured both the normal and attack traffic using Wireshark [25] and saved it into a .pcap file for further analysis.
3) Features Extraction: Once we got the .pcap file of both normal and attack network, we then extracted the features from .pcap file to train the machine learning classifiers for attack detection. For this purpose, we used a publicly available tool, i.e., CICFlowmeter [26] to extract the network traffic flow features of the given .pcap file and saved it into a .csv file. The CICFlowmeter [26] extracts more than 80 features from a .pcap file. The further details of these features are mentioned in [27]. We extracted network traffic features from the .pcap file and labelled them with respect to normal and attack device IP addresses. The final .csv file had 400 samples of both normal and attack traffic.
4) Features Selection:
Feature selection plays a significant role in the performance of a machine learning (ML) model as it selects the significant features which are imperative for data classification and ignores the useless features which can disturb the performance of ML model. For features selection, we used mutual information feature selection technique which calculates the mutual information among the features for a discrete target variable in order to select the important features from a dataset. We selected the top 10 features for better training and testing of the machine learning model.
5) Model Training:
After selecting the features, we split the data into training and testing set by randomly splitting 20% data for testing and 80% for training. We then trained and tested three commonly used ML models, i.e., Naive Bayes (NB), Random Forest (RF) and K-Nearest Neighbor (KNN) over the pre-processed dataset.
B. Performance Metrics
For the performance evaluation of the machine learning classifiers, we calculated three commonly used performance parameters over the testing data which include sensitivity, specificity and accuracy. The sensitivity is defined as the V. CONCLUSION Security is the major concern which may cramp the proliferation of IoT devices. Network traffic generation is a key technique which is used to design and analyze the performance of network security solutions like firewall, intrusion detection system (IDS), intrusion prevention system (IPS), etc. In this work, we proposed an open-source traffic generation framework, i.e., IoT-Flock which supports two IoT application layer protocols. Most of the existing open-source traffic generators lack of generating the attack traffic, however, IoT-Flock can generate both the attack and normal IoT traffic in order to train and test the IoT network security solutions. To demonstrate how the IoT-Flock can help in generating an IoT security solution, we first analyzed the traffic behaviour of a real-time smart home use case. We then created the smart home use case in IoT-Flock. After that, we created an attacking network to attack the IoT devices using IoT-Flock and captured the traces of both normal and attack traffic. Finally, we extracted the features then trained and tested the three commonly used machine learning algorithms for detecting the malicious traffic in IoT smart home use case. Among these models, Random Forest classifier performed the best with an accuracy of 99.99%. One can download IoT-Flock from GitHub [28], create real-time IoT use case, generate the use case traffic and test or design security solutions for IoT use case by utilizing IoT-Flock. Currently, IoT-Flock supports four recently reported IoT attacks, however, one can add more IoT attacks in the tool by extending the source code of the tool.
Fig. 1 .
1Layer-wise Core Functionalities of IoT-Flock the two widely used IoT application layer protocols, i.e., MQTT and CoAP. Moreover, it can generate the normal and attack traffic over a real-time network which is imperative for testing and evaluating the security solutions proposed for IoT.
TABLE I COAP
IMETHODS Requests to delete the resource identified by the URI Fig. 2. Flow Diagram of IoT-Flock message to the MQTT broker against the subscribed topic.Method
Description
GET
Retrieves the information corresponding to the URI request
POST
Requests the server to process the representation enclosed in
the request
PUT
Requests to update or create a resource identified by URI
DELETE
TABLE II ACTUAL
IITRAFFIC FEATURES
TABLE III EMULATED
IIITRAFFIC FEATURESDevice Name
Average
Mode
Average
Behavior
Device Name
Data Profile
Time Profile Behavior
Value
Time
Temp Sensor
33-35 C
180s
Periodic
Temp Sensor
34.72 C
35 C
180s
Periodic
Light Sensor
99-120 Lux
180s
Periodic
Light Sensor
120 Lux
100 Lux
180s
Periodic
Motion Sensor
0-1
3s-5s
Random
Motion Sensor
0.5
1
3s-5s
Random
Humidity Sensor
39-42 %
180s
Periodic
Humidity Sensor
40 %
42 %
180s
Periodic
TABLE IV RESULTS
IVability of the system to correctly detecting the attack. The specificity is defined as the ratio of normal packets that mistakenly are classified as malicious packet. The accuracy is defined as the ratio of correct predictions with respect to all samples. Mathematically, these are expressed in(2)-(4): Journal of Network and Computer Applications, vol. 87, pp. 185-192, 2017. [8] P. Megyesi, G. Szabó, and S. Molnár, "User behavior based traffic emulator: A framework for generating test data for dpi tools," Computer Networks, vol. 92, pp. 41-54, 2015. [9] Packet Sender, (accessed January 2, 2020). [Online]. Available: https://packetsender.com/ [10] D-ITG, (accessed January 12, 2020). [Online]. Available: http://www.grid.unina.it/software/ITG/ TP + FN + TN + FPTable IV summarizes the overall results of the three machine learning classifiers which are used for detecting malicious traffic.Parameters
NB
KNN
RF
Sensitivity
99.01
99.96
99.98
Specificity
95
99.88
99.99
Accuracy
97.14
99.92
99.99
Sensitivity =
TP + FN
× 100
(2)
TN
Specificity =
TN + FP
TP + TN
× 100
(3)
Accuracy =
× 100
(4)
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. NETWORK TRAFFIC FLOW ANALYZER. NETWORK TRAFFIC FLOW ANALYZER, (accessed January 6, 2020). [Online]. Available: http://www.netflowmeter.ca/netflowmeter.html
An Open-source Framework for IoT Traffic Generation. Iot-Flock, IoT-Flock: An Open-source Framework for IoT Traffic Generation, (accessed March 4, 2020). [Online]. Available: https://github.com/ThingzDefense/IoT-Flock
| Many problems are emerging in the process of application of the Internet of Things as a new industry.It is essential for the law to offer protections reasonably.Internet of Things mainly faces problems of four aspects:intellectual property protection problems of Internet of Things,information security protection problems,the legal requirements of industry standardization and standardization and the complex legal issues derived from thee applications of terminal devices.The solution of the problems should start at construction of China's legal environment about the Internet of Things,taking the improvement of eight aspects,such as the information security laws,capital control,industrial layered management,standardization construction as the typical measures. | With the development of the internet of things,the sensor technology has been constantly improved,which also begins to apply to all aspects of society,but is not perfect in the industrial equipment diagnosing management.Based on research of the sensor technology,the paper designs an industrial equipment diagnosing system.With sensor technology,the parameters of industrial site equipment can be detected and queried in real time.The wireless sensor network transmits the data to database server,and the data is finally processed by host computer.In this way the loss caused by reducing equipment failure can be reduced. | 1,999,711 | Help Wanted.
Desarrollamos Productos de IOT Industrial, Dispositivos Electrónicos, Sistemas Web con Dashboards y gestión de datos de tiempo real.
Software / Firmware / Electronics / Design, casi todo sirve
Preferentemente con disponibilidad para viajes esporádicos al extranjero. | Recomendación para utilizar Software libre y Sistema Operativo Linux | Implementación del sistema de comunicación en organizaciones innovadoras | Vorrei comprare un dispositivo mobile che mi permetta di far andare Anki per Windows (Vista/7/8/10) | Può un ISP impedirmi di hostare qualcosa su internet? | [BUSCO] Reparacion de pantalla de televisor | Aumento de velocidad de Internet para 2019? | Slack para Técnicos en Cs Datos del ISPC | Acceso al Nuevo Router de Altice (Work In Porgress) |
1,999,712 | Any other Brewers Friend users out there having problems with the footer covering critical parts of the page? | What is a footer and a header? | I'm having an issue with my footer. The padding is set to 25px all around, but the content within the footer is sitting along the bottom and there's no padding in site.
Sorry if I've included too many lines of code, I didn't want to leave anything out that could be effecting the issue, I can't figure out where this is coming from so it's hard to exclude lines.
Here is the applicable CSS:
footer {
padding: 25px;
background-color: hsl(0, 0%, 98%);
}
.footer-col {
width: 50%;
float: left;
}
.footer-col a {
padding-left: 5px;
font-family: "open sans";
text-decoration: none;
color: #660031;
}
/* We're pretending these black blocks are social media icons/links */
.social-media div {
background-color: black;
width: 25px;
height: 25px;
display: inline-block;
float: right;
margin-left: 10px;
}
HTML:
<footer>
<div class="footer-col">
<a href="/">home</a>
<a href="/about">about</a>
<a href="/contact">contact</a></div>
<div class="footer-col social-media">
<div></div>
<div></div>
<div></div>
</div>
</footer>
Link to Code Pen
Edit: fixed unclear wording about padding | My foot doesn’t touch the wall most of the time, and when it does I can’t get it to stay. Any tips or progressions? | The Mummy's Foot The Mummy's Foot () is a gothic short story by the French writer Théophile Gautier, first published in 1840. It relates the fantastical tale of a contemporary man and the adventures which befall him when he ventures into a Parisian curiosity shop and buys the four-thousand-year-old foot of Princess Hermonthis. A man enters an antiques shop and buys a mummified foot which supposedly belonged to an Egyptian princess, Hermonthis. He intends to use the foot as a paperweight. In the night, he sees a vision of the princess, who explains her foot has been stolen, and he | Is there something wrong with you if you wake up a your foot has gone completley numb? | I never understood how this is so common. Everyone leaves their bare feet in the picture. Either change the angle, or crop your feet out before uploading it | It has a hole in the feet. And the fabric is not good | Do any of you guys have the Get Shorter, Smaller Feet Smaller Hands - Biokinesis -? And Its a 28.40 minutes. It had the Cat thubmnail. | 1,999,712 | This has been going on for about 3 weeks. I can't see the last 4-5 things in any list, nor can I see some critical buttons like "Add Log Entry."
I found this work-around for Chrome, but it's a giant pain in the ass:
1) Right-click the box and select "Inspect element"
2) Search for "footerbox"
3) Right-click "<div id="footerbox"> and select "Delete node"
PS - looks like the site was sold to the owners of HBT. I'm glad I didn't fall for the lifetime membership if this is what we can expect from the new quality control standards. | Issue with Formstack on Chrome. Has anyone else had this problem? | I just logged in, and every single mod I've ever had is gone. | About the removal of the modded PF link&rules update | [MODPOST] Baophan122 has been banned Indefinitely | We've had posts automatically removed for no reason at all | I really miss login screens. | Did www.half-life3.com always link to the Orange box? | Did restored content mod erase cheese bugs? |
1,999,713 | where does chuck jura rank on the all time nebraska scoring chart | Chuck Jura all-time top 10 until at least 2006) and a few came from a record 20 field goals scored in a single 1968 game, he was inducted into the Nebraska High School Hall of Fame in 1995. Jura stayed in state for college, joining the University of Nebraska, who played in the Big Eight Conference of the NCAA University Division. He took part in 25 games in his first year as a sophomore, posting 9.9 points and 7.7 rebounds (both team second-bests) in 1969–70. His 59.2% field-goal percentage as a junior was the seventh best in the nation. He had 17.5 | 1995 Nebraska Cornhuskers football team near the Jayhawks' red zone for another. Kansas repeatedly drove deep into Nebraska territory but committed five turnovers. The Jayhawks' only points came on a field goal after an 86-yard drive stalled at the 2-yard line. Nebraska took over in the second half, and an 86-yard interception return by reserve defensive back Mike Fullman closed the scoring at 41–3. Tommie Frazier led all rushers with 99 yards on 10 carries; Kansas as a team ran for 72 yards on 32 rushing attempts. The Nebraska offense had three uncharacteristic turnovers, the first of which – a fumble by backup quarterback Brook | Nebraska Cornhuskers men's basketball record at "The Vault," Miles led the Cornhuskers to the program's first NCAA Tournament berth since 1998, but NU lost to Baylor in the first round. Despite appearing in the preseason nation top 25 for the first time in 20 years, Nebraska finished under .500 in 2014–15, and did not have a winning record again until 2017–18. On February 6, 2017, Nebraska suffered their worst home defeat in program history, closing the regular season with a 36-point loss to Michigan. The Cornhuskers maintain an intrastate rivalry with the Creighton Bluejays, which has comprised 51 games and has been played each | an overall record of 19–13, with a record of 11–7 in the Big Ten regular season. In the 2014 Big Ten Tournament, the Cornhuskers were defeated by Ohio State, 71–67 in the quarterfinals. They received at-large bid to the 2014 NCAA Men's Division I Basketball Tournament for the first time since 1998. They lost in the second round to Baylor. !colspan=9 style="background: #E11D38; color: #ffffff"| Exhibition !colspan=9 style="background: #E11D38; color: #ffffff"| Regular season !colspan=9 style="background: #E11D38; color: #ffffff"| Big Ten regular season !colspan=9 style="background: #E11D38; color: #ffffff"| Big Ten Tournament 2014–15 Nebraska Cornhuskers men's basketball team The 2014–15 Nebraska Cornhuskers | John Michael Hayden During his one season with the Muskateers the team compiled a 12-6-1 record. Xavier also earned an NSCAA national top 10 ranking while winning at both No. 2 Notre Dame and No. 1 Creighton. These results are widely considered to be the first time any team has knocked off the top two NSCAA-ranked teams on the road in the same season. In 2016 Hayden returned to the University of Louisville. Houston Dynamo selected Hayden in the first round (13th overall) in the 2007 MLS SuperDraft. He made his professional debut for them on 10 July 2007, in the Lamar Hunt | 2008 Nebraska Cornhuskers football team only to have their field goal kick blocked by Zach Potter. Nebraska's offense finally looked like it came together scoring 35 points. The scoring included Marlon Lucky taking a toss and throwing it downfield to quarterback Joe Ganz and then Ganz running 33 yards on an option play. Nebraska, 3–0, headed into the Virginia Tech game looking for a signature win in the first year of Bo Pelini's first year. It would not be on this night, though. Virginia Tech got on the board first, blocking a Dan Titchner punt for a safety. The Hokies controlled the game for most | The short answer to the question is yes, it is a GOOD statistic for measuring quarterbacks. The problem is when QBR's advocates, like Brian Burke on this page, present QBR as though it is the BEST metric for judging quarterbacks. QBR is based upon expected points added, which itself is an imperfect metric. | It was a winning weekend for one lucky Nebraska Lottery player, with a $50,000 winner sold at the Ampride on Avenue B in Scottsbluff.
The Nebraska Lottery says the winning ticket matched 4 of the 5 white balls, as well as the Powerball number.
Saturday’s winning numbers were: 25, 26, 37, 55 and 60 and the Powerball number was 6.
The Scottsbluff ticket was the highest winning ticket sold in Nebraska for Saturday’s drawing. The odds of matching 4 of the 5 numbers with the Powerball are listed as 1 in 913,129. | 1,999,713 | Chuck Jura end of the season. His last collegiate game was the NABC college All-Star game where he was selected on the West team. As of the 2014–15 season, Jura's career 740 rebounds rank as the seventh-best in Nebraska history at a rate of 9.6 per game (third-best), whilst his 1,255 points see him placed fifteenth on the all-time Nebraska scoring chart, with his 16.3 points average seventh-best and his .549 field goal percentage eighth-best. He was a charter member of the Nebraska Basketball Hall of Fame when the college created it in 1989. Selected by the Chicago Bulls in the third | when was chuck jura inducted into the nebraska high school hall of fame | when was the last time nebraska had a nba player in the class of 2018 | how many assists did craig ne neal have in college | when does kent bazemore's last game start | how many points did jamaal charles score in a game | who was the most valuable player on nebraska men's basketball team | who was the first player to play for nebraska in basketball | who recognized tommy casanova as the best college football player of all time |
1,999,714 | how much did j allen carnes donate to texas democrats | Whereas in May and June 2005 victory of the Christian Democrats seemed highly likely , with some polls giving them an absolute majority , this picture changed shortly before the election at 18 September 2005 , especially after the Christian Democrats introduced Paul Kirchhof as potential minister of the treasury , and after a television duel between Merkel and Schrà der where many considered Schrà der to have performed better . | The only reason I voted for BBM is so Aquino owns up to his crimes. I feel like the liberal party would use Robredo like a puppet and we go back to square one. | John McCain 2008 presidential campaign finances have been disclosed, while 4.4% has not. McCain was the first candidate to accept financing from the presidential election campaign fund checkoff. During the campaign's summer 2007 financial woes, it used a list of donors as collateral in order to get approval on a bank loan. This raised the question of whether the campaign's privacy policy was violated by such a use. A McCain spokesperson said it did not, since all of the campaign's assets were pledged as collateral at the time, not just the donor list. By December 2007, McCain was using 32 lobbyists as fundraisers, more than | I'm a Texas Dem just curious to see neoliberal's thoughts on him | Jerome G. Plante born January 8, 1935) is an American politician from Maine. Plante, a Democrat from Old Orchard Beach, Maine, served in the Maine House of Representatives from 1957 to 1964.
Plante served as Assistant Minority Leader during his 2nd and 3rd terms in the Maine House (1959-1960; 1961-1962) and as Minority Leader during his 4th and final term (1963-1964).
References
1935 births
Living people
People from Old Orchard Beach, Maine
Maine Democrats
Minority leaders of the Maine House of Representatives
Maine city managers | Bob Dole, a prominent Republican and former presidential candidate, defended his criticism of White House hopeful John Kerry's war record as "political hardball," saying he had merely "tweaked" the Democratic candidate. | 2008 United States presidential election in Oregon won each by a double-digit margin of victory and at least 52% of the vote. The final 3 polls showed Obama leading 55% to 41%. McCain raised a total of $1,258,426 in the state. Obama raised $6,660,622. Obama and his interest groups spent $1,194,908. McCain and his interest groups spent just $159,222. Neither campaign visited the state. Voters in Oregon have a strong penchant for advancing the protection of civil liberties and individual freedoms, liberal values that have given Democrats a big edge in the state in recent years. The state once leaned Republican, like most of the Pacific Northwest. | During his bid to be elected president in 2004, Kerry frequently criticized President George W. Bush for the Iraq War. While Kerry had initially voted in support of authorizing President Bush to use force in dealing with Saddam Hussein, he voted against an $87 billion supplemental appropriations bill to pay for the subsequent war. His statement on March 16, 2004, "I actually did vote for the $87 billion before I voted against it," helped the Bush campaign to paint him as a flip-flopper and has been cited as contributing to Kerry's defeat. | 1,999,714 | J. Allen Carnes one is automatically a "member" of the political party in whose primary and/or runoff election he participates. Only Democrats and Republicans in Texas normally hold primaries. He remains a "member" of that party for two years until the next regular primary or runoff. The only way he can "change" his party is to wait two years, then skip a primary and become an "unaffiliated" voter or to vote in the other party's primary and in effect "change" his partisan registration. He cannot switch from one party's primary and vote in the other party's immediate runoff election. Carnes donated about $5,000 | Sam Bell sure seems like a good choice for Democrats to vote for in the primaries given his pre-pandemic foresight into funding healthcare and other social programs | Rather than just unseating Repubs, how about going after an NDAA-Democrat in a primary in a safe seat? Delaware's Tom Carper is up for election and has no opposition. | Why WOULDN'Tt John McCain make it passed a republican primary? Explain? | Bernie endorses 17 state legislative candidates | How many political parties had candidates in the 1824 presidential electon? | 2020 Libertarian Party presidential primaries | The present study tests the theory that states can impact the size of the grants they receive (per capita) from the federal government by becoming pivotal players in the federal electoral (primary/caucus) process. That is, by rearranging their presidential primary and caucus dates, states can play an important role in determining the field of candidates for the two major political parties in the United States. States are then likely to be rewarded within the budgetary process at the federal level, which begins with the executive branch. Results from a simultaneous equation system suggest that the impact of the average movement of primaries/caucuses in the sample period (10.36 days closer to 1 January) results in an increase of federal grants of $362 million to $1.2 billion (over a two-year period) for the average state. These results are consistent with the current pattern in the American political process of more front-ended presidential primaries and caucuses. Copyright 2001 Western Economic Association International. | who is steny hoyer running against in the republican primary |
1,999,715 | Voltage converter for the operation of lamps | 110v lamp into 220v? | A 120 V mains-driven class-E converter used as an electronic ballast for a 15 W fluorescent lamp is presented. The key element of the circuit is a cascoded bipolar metal-oxide semiconductor (BiMOS) switch which ensures high-voltage and high-frequency capability. In spite of the high switching frequency of 450 kHz an excellent efficiency of 91 percent could be achieved. Thus miniaturization becomes feasible. | In this paper, a novel true parallel lamp operation universal programmed start dimming ballast platform for fluorescent lamps is proposed. The proposed platform is based on a decoupled half-bridge inverter. The proposed platform ensures true parallel lamp operation and maintains constant current through each lamp even when lamps are extremely unbalanced. The proposed platform ensures good preheat and steady state filament heating in dimming by using independent PWM type filament heating control method. The proposed platform can be applied to drive different types of lamps in one design. The proposed platform ensures half-bridge MOSFETs soft-switching all the time. Mathematical analysis of the proposed platform is discussed in the paper. Experimental results are presented to validate the proposed method. | I had to fiddle with the tab inside this converter to get a viable connection for it to work after repairing the metal tounge/tab it worked well for converting my antique floor lamp to a standard based bulb. | PURPOSE: A lamp, a method for fabricating the lamp, a back light assembly and an LCD(Liquid Crystal Display) having the lamp are provided to remarkably reduce driving voltage and power consumption of the lamp by constructing the electrode of the lamp of a solder electrode. CONSTITUTION: A lamp(100) includes a lamp body(110), the first electrode(120) and the second electrode(130). The lamp body includes a fluorescent layer and a discharge gas. The first electrode has a tube shape such that the end of the lamp body is inserted into the first electrode. The second electrode is molten between the inner side of the first electrode and the surface of the lamp body to fix the first electrode and the lamp body. | I need to know what resistor I need for theese neon lamps each one is going to be run from 120vac. :A1a( 5.75*23.45mm). A1a (5.80*14.4mm) | A method of driving a lamp with a lamp control circuit, the lamp control circuit includes a communication circuit, and a lamp driving circuit. The lamp driving circuit is configured to drive a lamp according to a number of lamp operating parameters. The method includes supplying a lamp operating parameters in the memory of the communication circuit, and supplying a supply voltage to the lamp driving circuit, and supplying the lamp operating parameter to the lamp drive circuit from said memory a. Then, the by the lamp drive circuit, in response to the lamp operating parameters supplied to drive the lamp. In the lamp control circuit, said communication circuit has a memory, when the supply voltage to the lamp driving circuit is supplied, configured to supply the lamp operating parameter to the lamp drive circuit. In an embodiment, the lamp operating parameters, when the supply voltage to the lamp control circuit is not supplied, may be supplied to the memory. | Can in put a 120 volt bulb in a 130 volt lamp? | 1,999,715 | Disclosed is a voltage converter for providing a DC voltage (Vout) for operating at least one LED-path (1), wherein the converter is arranged to: a.) a preferably (in a voltage range above the forward voltage of the LED route 1) under measurement of the LED current (iL) to output at least once up and down (from the changing DC voltage Vout), and b.) depending on this measurement the operating point of the DC voltage (Vout) to adjust. | Voltage source converter control method, and a voltage conversion device | leds can be operated on what kind of voltage | I just returned from a trip to Brazil where I ... NOT A VOLTAGE CONVERTER AS IT STATES! | Dc-dc Converter Circuit For High Input-to-output Voltage Conversion | What is diodes forword voltage? | what is the definition of voltage regulation in electrical engineering | what is the name of a dc-to-dc converter that steps down voltage while | What is dc nominal voltage? |
1,999,716 | I still love it and still get compliments | I got this thing years ago and it still looks brand new I don't wear it often but wen I do i always get compliments | Cannot tell you how many compliments I get on this - from men and women alike. It is very unique and has held up well for me so far. | My opinion is still up in the air. So far tho I love it! | I owned it years ago, its one of the best! Still love it. | Wasn't the style I'm used to. But still satisfied with the purchase. | have gotten many complements on it. I absolutely love it. | I got on the clump crusher bandwagon and I really disliked it. It just flaked horribly and made my lashes look stubby. So, what else do you guys like? | I love it and everybody give me a lot of compliments when they notice it at the restaurant. (Im a waitress) | 1,999,716 | I think I bought this cover two years ago. I still love it and still get compliments. | I really likes this cover. It gives a different ... | ... felt compelled to let others know that this is FANTASTIC cover! My last cover was twice as expensive ... | I bought one a year ago and I loved it at first - much better quality than covers ... | ... this cover under a year ago I was generally pleased. It fit well and wasn't so snug that ... | Its been like 3 years since i bought this cover and it ... | I loved this cover when I first got it | was the best cover I have had in 25 years of owning ... | previous cover just like this one lasted 5 years |
1,999,717 | On finite element discretizations of the pure Neumann problem | Summary.Neumann-Neumann algorithm have been well developed for standard finite element discretization of elliptic problems with discontinuous coefficients. In this paper, an algorithm of this kind is designed and analyzed for a mortar finite element discretization of problems in three dimensions. It is established that its rate of convergence is independent of the discretization parameters and jumps of coefficients between subregions. The algorithm is well suited for parallel computations. | Finite Element and Boundary Element Applications in Quantum Mechanics | This paper provides an equivalent characterization of the discrete maximum principle for Galerkin solutions of general linear elliptic problems. The characterization is formulated in terms of the discrete Green’s function and the elliptic projection of the boundary data. This general concept is applied to the analysis of the discrete maximum principle for the higher-order finite elements in one-dimension and to the lowest-order finite elements on simplices of arbitrary dimension. The paper surveys the state of the art in the field of the discrete maximum principle and provides new generalizations of several results. |
INTRODUCTION
The finite element method has achieved great success in many fields of science and technology since it was first suggested in elasticity in the fifth decade of 20 th century.Today it has become a powerful tool for solving partial differential equations [1,2].The key issue of the finite element method is using a discrete solution on the finite element space,usually consisting of piecewise polynomials,to approximate the exact solution on the given space according to a certain kind of variational principle.When the finite element space is a subspace of the solution space, the method is called conforming.It is known that in this case,the finite element solution converges to true solution provided the finite element space approximates the given space in some sense.
In general, for a 2m order elliptic boundary-value problem,the conforming finite element space is a C m−1 subspace.It means that the shape function in this conforming finite element space is continuous together with its m − 1 order derivatives.That is for a second-order problem, the shape function is continuous and for a fourth order problem, the shape functions and its derivatives are continuous.It is a rather strong restriction put on the shape functions in the latter case.
It is prove that to build up a conforming finite element space with C 1continuity for a two dimensional fourth-order problem, like the plate bending problem in elasticity, at least a quintic polynomial with 18 parameters is required for a triangular element and a bi-cubic polynomial with 16 parameters for a rectangular element.It causes some computational difficulties because the dimension of the related finite element space is fairly large and its structure is rather complicated.
Therefore, it is desirable to relax directly the C m−1 continuity of the finite element space.It comes to the so called 'nonconforming' finite element method which had and still has a great impact on the development of finite element methods.However, it was found that some nonconforming element elements converge and some do not. The convergence behaviour sometimes depends on the mesh configuration.
Up to now there has been proposed a vast number of engineer devices based on different mechanical interpolations,like unconventional elements,energy-orthogonal elements with free formulation,quasi-conforming elements,generalised conforming elements and many others.The approximate spaces related to all these elements mentioned above are not included in the given solution space.Hence they are simply called 'nonstandard' finite elements.A unified mathematical treatment for analysis of these nonstandard finite elements has been proposed by various authors.
A brief description and analysis of some interesting and important conforming and nonconforming finite elements has been given below. P 1 nonconforming element [2,1]. This is a triangular element which is not C 0 . The shape function is a linear polynomial with three nodal parameters at mid points of three edges of the triangle.This element converges for second order elliptic problem with optimal rate.
Wilson-element [3,4,5]. This is a nonconforming rectangular element.The shape function is a quadratic polynomial with six parameters, four at vertices of the rectangle and two internal degrees of freedom, like the second order derivatives.This element converges for rectangular mesh, but does not converge for arbitrary quadrilaterals.It is interesting to mention that the behaviour of the Wilson element is better than the corresponding bilinear Q 1 conforming element as many engineering example have indicated.
The rotated Q 1 element [6,7,8]. This is a newly established non-conforming rectangular element.The shape function consists of four terms as[1,x,y,x 2 − y 2 ].There are two versions of choosing nodal parameters.The first one uses four function values at the mid-point of each edge of the rectangle.The second version uses four mean values of the shape function along edges. Both versions are convergent for rectangular meshes.However,the first version is not convergent for arbitary quadrilaterals unless certain mess conditions are satisfied.
Morley element [9] This is an old and simplest plate element.The shape func-tion is a quadratic polynomial with six nodal parameters.They are three function values at vertices and three normal derivatives at mid-points of three edges.This element does not even belong to C 0 class,nevertheless it is convergent for the fourth-order problem [10] . Surprisingly, it is recently proved that the Morley element is divergent for the second-order elliptic problem [11]. In contrast, it is well known that there exists for long time the P 2 conforming element for the second order problem.Its shape function is again a quadratic polynomial with six parameters as three function values at vertices and three function values at mid-points of edges.This quadratic C 0 element is convergent for the second order problem, but divergent for the fourth-order problem.
Zienkiewicz incomplete cubic triangular element [12]. The shape function consists of incomplete cubic polynomials with specially chosen nine terms.The nine nodal parameters are three function values together with six first partial derivatives with respect to x and y at three vertices.This is a C 0 element but not C 1 .It is proved that this element is convergent only for very special meshes, namely, all edges of triangles are parallel to the three given directions.It is a very interesting phenomenon that the Zienkiewicz element using the crossdiagonal mesh actually tend to a limit,but it is not the true solution of the given problem,rather of another problem [13] .
Another new nonconforming piecewise quadratic finite element on triangles has been discussed in [14].This element satisfy patch test of Irons and Razzaqque [15].This implies that on element interfaces,one should ensure the continuity of the approximation at the Gauss-Legendre quadrature points needed for the exact integration of third-degree polynomials. Optimal-error estimates and regularity properties for Dirichlet's problem has been studied by authers. In this paper we will propose a new finite element which is a bridge between conforming and nonconforming finite element.This new element piecewise quadratic and quasi conforming.We have studied error estimation for Dirichlet's problem,and observed that this element does not give optimal convergence rate,which has been generally considered as a major drawback against the use of this element.Though the element is piecewise quadratic but it does not require two point continuity restriction on each interface of τ h ,which is needed for the above mentioned piecewise quadratic nonconforming element [14].We shall show here that these elements are in fact very simple to use and they are nothing but combination of P 1 nonconforming element with incomplete P 2 -conforming element.
Discretization
Continuous Problem
We consider the following model problem
−∆u = f in Ω (1) u = u D on ∂Ω
where Ω ⊂ R 2
Notation
Let τ h be a conforming triangulation of Ω.The subscript h refer to the maximum element size h = max k∈τ h h k , where h k is the diameter of an element K ∈ τ h .ε h is the set of the edges in τ h , n is the unit outward normal along ∂K and the jump [u] across an edge e is a vector defined as follows-Let e be an interior edge shared by two triangles K 1 and K 2 in τ h , and ω j = ω| Kj for j=1,2 . We define on e
[ω] = ω 1 n 1 + ω 2 n 2 where n j is the unit normal of e pointing towards the outside of K j .If e is an edge on the boundary of Ω,then we define on e
[ω] = ωn where n is the unit outer normal of e pointing towards the outside of Ω.
Weak Formulation
Find u ∈ V = H 1 0 (Ω) such that a(u, v) = F (v) ∀ v ∈ V = H 1 0 (Ω) where a(u, v) = Ω ∇u.∇v (2) F (v) = Ω f v(3)
Ω is convex polygon and f ∈ L 2 (Ω) therefore u ∈ H 2 (Ω) by elliptic regularity theory [16].
NC1-C2 methods
In order to define a nonconforming space,we introduce some further notation. Fig 2].φ 1 ,φ 2 ,φ 3 are basis fn on reference triangleK corresponding to the verticesb 1 ,b 2 ,b 3 respectively, which is defined bŷ
V 1 h = {v ∈ L 2 (Ω) : v| K is linear ∀ K ∈ τ h , v is continuous at the mid points of the edges of τ h } The above space is basically p 1 -nonconforming space. We define D 2 K = span{φ 1 , φ 2 , φ 3 };where φ i =φ i •F −1 K and F K is Affine mapping fromK to K [φ 1 = (−1 + 2x + 2y)(−1 + x + y) φ 2 = (2x − 1)x φ 3 = (2y − 1)y φ i , 1 ≤ i ≤ 3
is continuous along edge on each element.In this paper we use the following finite element space-
V h := V 1 h ⊕ V 2 h , V 2 h := {v h ∈ L 2 (Ω) : v h | K ∈ D 2 K } Finite element space V h
consists of piecewise quadratic function which is discontinuous along edge of each triangle except at mid points of edges [Fig 1].
A typical element ω ∈ V h is demonstrated below- ω = ω 1 + ω 2 where ω 1 ∈ V 1 h and ω 2 ∈ V 2 h
since ω 1 is discontinuous along edges except at the midpoints and ω 2 is continuous along edge, ω is discontinuous along edges except at the mid points.
On interior edges jump of typical element is reduced to P 1 polynomial .Let e be an interior edge which is shared by two triangle K 1 and K 2 . ω| K 1 and ω|K 2 are restrictions of ω on K 1 and K 2 respectively.
[ω] = ω|K 1 − ω|K 2
= (ω 1 |K 1 + ω 2 |K 1 ) − (ω 1 |K 2 + ω 2 |K 2 ) = (ω 1 |K 1 − ω 1 |K 2 ) + (ω 2 |K 1 − ω 2 |K 2 ) = (ω 1 |K 1 − ω 1 |K 2 )(4)
This space contains the space of continuous piecewise-quadratic and space of nonconforming piecewise-linear,since
V h = V 1 h + P 2 h
where P 2 h is piecewise-quadratic conforming finite element space.
Discretization
The space V h is not continuous and hence it is no longer in H 1 0 (Ω).We must modify the variational form a h (., .) in the discretized problem.We define the following bilinear form on V h + V * .where V * is subset of V and exact solution belongs to V * .
a h (v, ω) = K∈τ h K ∇v.∇ω dx (5) F h (ω) = K∈τ h K f ω(6)
Consistency
Let u ∈ V * ⊂ V such that u satisfies weak formulation,i,e
a(u, ω) = F (ω) ∀ ω ∈ V(7)
Then it is obvious that
a h (u, ω) = F h (ω) ∀ ω ∈ V h(8)
Hence the discrete bilinear form is consistent.It also satisfies Galerkin's orthogonality condition since
a h (u − u h , ω) = 0 ∀ ω ∈ V h(9)
Discrete stability
The discrete bilinear form a h (., .) enjoys discrete stability on V h if there is C sta > 0 such that
c sta v h ≤ sup ω h ∈V h \{0} a h (v h , ω h ) ω h (10) a h (v h , ω h ) = K∈τ h K ∇v h .∇ω h(11)
considering
v h = ω h v h 2 = K∈τ h K |∇v h | 2 = a h (v h , v h )(12)
Hence
v h = a h (v h , v h ) v h ≤ sup ω h ∈V h \{0} a h (v h , ω h ) ω h(13)
Hence a h (., .) satisfies discrete stability condition.This implies the discrete bilinear form
a h (u, ω) = F h (ω) ∀ u, ω ∈ V h(14)
is well posed i.e. the discrete bilinear form has unique solution.
Apriori Error Estimation
Lemma 1 Assume dim V h < ∞.Let a h (..) be a symmetric positive definite bilinear form on V + V h which reduces to a(.,.) on V.Let u ∈ V solve
a(u, v) = F (v) ∀ v ∈ V where F ∈ V ′ ∩ V ′ h .Let u h ∈ V h solve a h (u h , v) = F (v) ∀ v ∈ V Then u − u h h ≤ inf v∈V h u − v h +sup ω∈V h \{0} |a h (u − u h , ω) ω h(15)
where . h = a h (., .)
proof:-Letũ h ∈ V h satisfies a h (ũ h , v) = a h (u, v) ∀ v ∈ V h which implies that a h (ũ h − u, v) = 0 ∀ v ∈ V h ⇒ u −ũ h h = inf v∈V h u − v h Then u − u h h ≤ u −ũ h h + ũ h − u h h ≤ u −ũ h h +sup ω∈V h \{0} |a h (ũ h − u h , ω)| ω h
Lemma 2 Let K be an arbitrary element of conforming triangulation τ h .Then the following inequality holds
|e| −1 ζ 2 L 2 (e) ≤ C(h −2 K ζ 2 L 2 (K) +|ζ| 2 H 1 (K) ) ∀ ζ ∈ H 1 (K)(16)
where |e| denotes the length of edge e ⊂ ∂K, h K =diam K,and the positive constant depends only on the chunkiness parameter of K.
Proof: See the details in [1] Lemma 3 Let all assumptions of Lemma 2 hold and ω be an arbitrary element of V h .Then
|e| [ω] 2 L 2 (e) ≤ C K∈τe h 2 K |ω| 2 H 1 (K)(17)
where [ω] denotes jump of ω along edge e ∈ ε h .
Proof: Using lemma 2 we can write
|e| −1 [ω] 2 L 2 (e) ≤ C K∈τe (h −2 K ω 2 L 2 (K) +|ω| 2 H 1 (K) ) |e| [ω] 2 L 2 (e) ≤ C K∈τe (|e| 2 h −2 K ω 2 L 2 (K) +|e| 2 |ω| 2 H 1 (K) )
Where τ e is the set of triangles in τ h containing e on their boundaries. Again
[ω] =0 at midpoint of each edge of K hence first part of of right-hand side will be vanished.Therefore we have
|e| [ω] 2 L 2 (e) ≤ C K∈τe |e| 2 |ω| 2 H 1 (K) ≤ C K∈τe h 2 K |ω| 2 H 1 (K)|u − Q m u| W k p (Ω) ≤ C m,n,γ d m−k |u| W m p (Ω) k = 0, 1,. .., m,(18)
where d=diam(Ω) and ρ max =sup { ρ : Ω is star-shaped with respect to a ball of radius ρ } Proof: See the details in [1]
3.1
The important ingredient in the error analysis is a bound on the approximation error u − u I where u I ∈ V h is a suitable interpolation which agrees with u at mid point of each edges of ε h of exact solution u.The interpolation operator is defined at the element level. We just require the local approximation property
|u − u I | H s (K) ≤ Ch p+1−s K |u| H p+1 (K) ∀ K ∈ τ h , s = 0, 1, 2
It will be useful to define it explicitly.It is defined in two steps. LetK be the reference triangle with verticesb 1 ,b 2 ,b 3 whose coordinates are (0,0),(1,0),(0,1) respectively andm i be the midpoint of the side joining i and i+1(modulo 3) vertices. We defineÎ
1 (û) =û(m 1 )φ 4 +û(m 2 )φ 5 +û(m 3 )φ 6 I 2 (û) = (û(b 1 ) −Î 1 (û)(b 1 ))φ 1 + (û(b 2 ) −Î 1 (û)(b 2 ))φ 2 + (û(b 3 ) −Î 1 (û)(b 3 ))φ 3
Finally we define interpolation aŝ
I(û) =Î 1 (û) +Î 2 (û) = 6 j=1L j (û)φ j(19)
whereL i for i=1,2,3,4,5,6 continuous linear functional.
Now we will show that P 2 (K) is unisolvent with respect to these functionals, i.e.for an arbitrary polynomialp ∈ P 2 (K)L i (p) = 0 impliesp = 0. Sincep ∈ P 2 (K) implies thatp can be written as linear combination of basis of P 2 (K) .Thenp
= 6 i=1 C i φ i . C 4 =p(m 1 ) =L 4 (p) = 0 C 5 =p(m 2 ) =L 5 (p) = 0 C 6 =p(m 3 ) =L 6 (p) = 0 ⇒p = C 1φ1 + C 2φ2 + C 3φ3 again C 1 =p(b 1 ) =L 1 (p) = 0 C 2 =p(m 2 ) =L 2 (p) = 0 C 3 =p(m 3 ) =L 3 (p) = 0 ⇒p = 0
Similarly it can be shown that for arbitraryp ∈ P 2 (K),Î(p) =p . Let (K, P 2 (K), Σ) be an affine finite element of (K, P 2 (K),Σ) where Σ = {L 1 , L 2 , L 3 , L 4 , L 5 , L 6 } andΣ = {L 1 ,L 2 ,L 3 ,L 4 ,L 5 ,L 6 } . Then for all v ∈ H m+1 (K) we have
D s (u − I h u) L 2 (K) ≤ C h m+1−s K D m+1 u L 2 (K)(20)
where s ≤ m + 1 and m=0,1,2.
3.2
We want to find out u − u h h Using lemma 1 we can write
u − u h h ≤ inf v∈V h u − v h +sup ω∈V h \{0} a h (u − u h , ω) ω h inf v∈V h u − v h ≤ u − u I h ≤ C h 2 |u| H 3 (Ω) by (20)(21)
Now we have to estimate
sup ω∈V h \{0} |a h (u−u h ,ω)| ω h a h (u − u h , ω) = K∈τ h K ∇u.∇ωdx − Ω f ωdx = k∈τ h [ ∂k ∇u.ωnds − K ∆uωdΩ] − K f ωdΩ = K∈τ[ω] L 2 (e) ≤ ( e∈ε h |e| −1 ∇u.n e − C e 2 L 2 (e) ) 1 2 ( e∈ε h |e| [ω] 2 L 2 (e) ) 1 2 ≤ C[ e∈ε h min K∈τe (h −2 K ∇u.n e − C e 2 L 2 (T ) +|u| 2 H 2 (K) )] 1 2 [ e∈ε h K∈τe h 2 K |ω| 2 H 1 (K) ] 1 2 by (16, 17) ≤ Ch|u| H 2 (Ω) ω h Hence we have |a h (u − u h , ω)| ≤ C h |u| H 2 (Ω) ω h ⇒ |a h (u − u h , ω)| ω h ≤ C h |u| H 2 (Ω) ⇒ u − u h h ≤ C h |u| H 2 (Ω) using (21) (24) 3.3 L 2 -Error Estimate Let η ∈ H 2 (Ω) H 1 0 (Ω) satisfy a(η, v) = Ω v(u − u h ) ∀ v ∈ H 1 0 (Ω) and η h ∈ V h satisfy a h (η h , v) = Ω v (u − u h ) ∀ v ∈ V h Again we have u − u h 2 L 2 (Ω) = Ω (u − u h ) 2 = Ω (u − u h )(u − u h ) = Ω u(u − u h ) − Ω u h (u − u h ) = a(u, η) − a h (u h , η h ) = a h (u, η) − a h (u h , η) + a h (u h , η) − a h (u h , η h ) = a h (u − u h , η) + a h (u h , η − η h ) = a h (u − u h , η − η h ) + a h (u − u h , η h ) + a h (u h , η − η h )(25)
Using estimation (24) we can write
a h (u − u h , η − η h ) ≤ u − u h h η − η h h (using Cauchy-Schwarz ) ≤ C h 2 |u| H 2 (Ω) |η| H 2 (Ω)(26)
Where C is generic constant. Where C e is arbitrary constant and we have used the following two identity
a h (u − u h , η h ) = a h (u − u h , η h − η I ) + a h (u − u h , η h ) a h (u − u h , η h − η I ) ≤ u − u h h η h − η I h ≤ C h 2 |u| H 2 (Ω) |η| H 2 (Ω) η h − η I h = η h − η + η − η I h ≤ η h − η h + η − η I h ≤ C 1 h |η| H 2 (Ω) + C 2 h |η| H 2 (Ω) = C h |η| H 2 (Ω) a h (u − u h , η I ) =[η] = 0 & e [η I ] = 0 a h (u − u h , η I ) ≤ e∈ε h |e| − 1 2 ∇u.n e − C e L 2 (e) |e| 1 2 η − η I L 2 (e) ≤ C [ e∈ε h min K∈τe (h −2 K inf Ce∈R ∇u.n e − C e 2 L 2 (K) +|u| 2 H 2 (K) )] 1 2 × [ e∈ε h |e| 2 K∈τe (h −2 K η − η I 2 L 2 (K) +|η − η I | 2 H 1 (K) )] 1 2
≤ C |u| H 2 (Ω) (h 2 |η| H 2 (Ω) ) using (18, 20)
Therefore
a h (u − u h , η h ) ≤ C h 2 |u| H 2 (Ω) |η| H 2 (Ω)(27)
Again we have
a h (u h , η − η h ) = a h (η − η h , u h ) = a h (η − η h , u h − u I ) + a h (η − η h , u I ) (28) a h (η − η h , u h − u I ) ≤ η − η h h u h − u I h and u h − u I h = u h − u + u − u I h ≤ u − u h h + u − u I h ≤ C h|u| H 2 (Ω) Therefore a h (η − η h , u h − u I ) ≤ C h 2 |η| H 2 (Ω) |u| H 2 (Ω)(29)
We can write second term of (28) as
a h (η − η h , u I ) =
Hence
a h (u h , η − η h ) = a h (η − η h , u h − u I ) + a h (η − η h , u I ) ≤ C h 2 |η| H 2 (Ω) |u| H 2 (Ω)(31)
Using estimations (26),(27),(31) in (25) we can write
u − u h 2 L 2 (Ω) ≤ C h 2 |η| H 2 (Ω) |u| H 2 (Ω)(32)
using elliptic regularity we can write
η H 2 (Ω) ≤ C u − u h L 2 (Ω)(33)
Therefore u − u h L 2 (Ω) ≤ C h 2 |u| H 2 (Ω)
Numerical Test
In this section we perform grid convergence studies for the proposed 'NC1-C2' method.The new method was implemented using penalization technique.We estimate the experimental order of convergence by the formula
Eoc = log( E(2h) E(h) )
where E(h) = u − u h is the error in the specified norm.The result indicate the same convergence behaviour for NC1-C2 method and and p 1 -nonconforming method.We have glued second order conforming element with first order nonconforming element suitably and observed that first order nonconforming element dominated second order conforming element and we have obtained an EOC of 2.0 in the L 2 norm and 1.0 in the H 1 norm which is same as p 1 nonconforming method.EOC stands for experimental order of convergence.
Stationary Diffusion Problem : We consider the Poisson equation
− ∆u = f on Ω = (0, 1) × (0, 1)
with homogeneous boundary conditions and the right hand side f = 2π 2 sin(πx)sin(πy).
The exact solution is given by u(x, y) = sin(πx)sin(πy).
Figure 1 :
1NC1
Figure 2
2Let B be a ball in Ω such that Ω is star-shaped with respect to B and such that its radius ρ > ( 1 2 )ρ max . Let Q m u be the Taylor polynomial of order m of u averaged over B where u ∈ W m p (Ω) and p ≥ 1.Then
.n e − C e ) n e .[η I − η] ds
u
.n e − C e ) n e .[u − u I ] ds where we have used the following two identity [u] = 0 & e [u I ] = 0 ,e is an interior edge. Therefore a h (η − η h , u I ) = e∈ε h e (∇η.n e − C e ) n e .[u − u I ] − u I L 2 (e) ≤ C |η| H 2 (Ω) (h 2 |u| H 2 (Ω) )
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| We investigate the discretization of optimal boundary control problems for elliptic equations on two-dimensional polygonal domains by the boundary concentrated finite element method. We prove that the discretization error $\|u^{*}-u_{h}^{*}\|_{L^{2}(\Gamma)}$ decreases like N ?1, where N is the total number of unknowns. This makes the proposed method favorable in comparison to the h-version of the finite element method, where the discretization error behaves like N ?3/4 for uniform meshes. Moreover, we present an algorithm that solves the discretized problem in almost optimal complexity. The paper is complemented with numerical results. | The paper analyzes a continuous and discrete version of the Neumann-Neumann domain decomposition algorithm for two-body contact problems with Tresca friction. Each iterative step consists of a linear elasticity problem for one body with displacements prescribed on a contact part of the boundary and a contact problem with Tresca friction for the second body. To ensure continuity of contact stresses, two auxiliary Neumann problems in each domain are solved. Numerical experiments illustrate the performace of the proposed approach. |
Introduction
This paper is concerned with numerical schemes for second order distributed optimal control problems governed by diffusion equations with Dirichlet and Neumann boundary conditions (BC). We present basic convergence results and superconvergence results for the state, adjoint and control variables. Our results cover various numerical methods, including conforming Galerkin methods, non-conforming finite elements, and mimetic finite differences. This is achieved by using the framework of the gradient discretisation method.
The gradient discretisation method (GDM) is a generic framework for the convergence analysis of numerical methods for diffusion equations. The GDM consists in replacing the continuous space and operators by discrete ones in the weak formulation of the partial differential equation (PDE). The set of discrete elements thus chosen is called a gradient discretisation (GD), and the scheme obtained by using these elements is a gradient scheme (GS). The variety of possible choices of GDs results in as many different GSs, allowing the GDM to cover a wide range of numerical methods (finite elements, mixed finite elements, finite volume, mimetic methods, etc.). Reference [19] presents the methods known to be GDMs, and [14,15,18,20,[22][23][24] provide a few models on which the convergence analysis can be carried out within this framework; see also [16] for a complete presentation of the GDM for various boundary conditions and models.
Date: March 19, 2018. In this paper, we discretise optimal control problems governed by diffusion equations using the gradient discretisation method. A gradient scheme is defined for the optimal control problem by discretising the corresponding optimality system, which involve state, adjoint and control variables. Error estimates of two kinds are derived for the state, adjoint and control variables. Firstly, we establish basic error estimates in a very generic setting. Secondly, considering slightly more restrictive assumptions on the admissible control set, we derive super-convergence results for all three variables. The theoretical results are substantiated by numerical experiments.
Numerical methods for second-order optimal control problems governed by Dirichlet BC have been studied in various articles (see, e.g., [5,10,28,33,34] for distributed control, [2,32] for boundary control, and references therein). For conforming and mixed finite element methods, superconvergence result of control has been derived in [11,12,34]. For the finite element analysis of Neumann boundary control problems, see [3,4,9,29,31]. However, to the best of our knowledge, super-convergence has not been studied for classical non-conforming methods for control problems governed by second order linear elliptic problems. One of the consequences of our generic analysis is to establish superconvergence results for several conforming and non-conforming numerical methods covered by gradient schemes -in particular, the classical Crouzeix-Raviart finite element method and the mixed-hybrid mimetic finite difference schemes. Note that we only consider linear control problems here, but the GDM has been designed to also deal with non-linear models. So for non-linear state equations that are amenable to error estimates (e.g. the p-Laplace equation [16,Theorem 3.28]), an adaptation of the results presented here is conceivable.
The paper is organised as follows. Subsection 1.1 defines the distributed optimal control problem governed by the diffusion equation with homogeneous Dirichlet BC. Two particular cases of our main results are stated in Subsection 1.2; these cases cover non-conforming finite element methods and mixed-hybrid mimetic finite difference schemes. In Section 2, the GDM is introduced, the concept of GD is defined and the properties on the spaces and mappings that are important for the convergence analysis of the resulting GS are stated. The basic error estimates and superconvergence results for the GDM applied to the control problems are presented in Section 3. The superconvergence for the control variable is obtained under a superconvergence assumption on the underlying state and adjoint equations which, if not already known, can be checked for various gradient schemes by using the improved L 2 estimate of [21]. Note that our superconvergence results are twofold. Under generic assumptions on the GD, which allow for local mesh refinements, we prove an O(h 2− ) super-convergence with > 0 in dimension 2 and = 1/6 in dimension 3. Under an L ∞ -bound assumption on the solution to the GS, which for most methods requires the quasi-uniformity of the meshes, we prove a full O(h 2 ) convergence result. Section 4 deals with the proof of the main results which are stated in Section 3. The superconvergence is established by following the ideas developed in [34] for conforming finite elements. In Section 5, the distributed and boundary optimal control problems with Neumann BC is presented. The GDM for Neumann BC is discussed in this section and the core properties that the GDs must satisfy to provide a proper approximation of given problem are highlighted. We present the results of some numerical experiments in Section 6. An appendix, Section 7.1 recalls the GD corresponding to mixed hybrid mimetic schemes and derives L ∞ estimates. Since the paper deals with a variety of methods, we conclude this introduction with a list of some abbreviations used throughout the paper (see Table 1). where Ω R n (n ≥ 2) is a bounded domain with boundary ∂Ω; y is the state variable, and u is the control variable;
J(y, u) := 1 2 y − y d 2 L 2 (Ω) + α 2 u − u d 2 L 2 (Ω) (1.2)
is the cost functional, α > 0 is a fixed regularization parameter, y d ∈ L 2 (Ω) is the desired state variable and u d ∈ L 2 (Ω) is the desired control variable; A : Ω → M n (R) is a measurable, bounded and uniformly elliptic matrix-valued function such that (for simplicity purposes) A(x) is symmetric for a.e. x ∈ Ω; f ∈ L 2 (Ω); U ad ⊂ L 2 (Ω) is the non-empty, convex and closed set of admissible controls.
It is well known that given u ∈ U ad , there exists a unique weak solution y(u) ∈ H 1 0 (Ω) := {w ∈ H 1 (Ω) : w = 0 on ∂Ω} of (1.1b)-(1.1c). That is, for u ∈ U ad , there exists a unique y(u) ∈ H 1 0 (Ω) such that for all w ∈ H 1 0 (Ω),
a(y(u), w) = Ω (f + u)wdx, (1.3)
where a(z, w) = Ω A∇z · ∇wdx. The term y(u) is the state associated with the control u.
In the following, we denote by · and (·, ·), the norm and scalar product in L 2 (Ω) (or L 2 (Ω) n for vector-valued functions). The convex control problem (1.1) has a unique weak solution (y, u) ∈ H 1 0 (Ω) × U ad . Also there exists a co-state p ∈ H 1 0 (Ω) such that the triplet (y, p, u) ∈ H 1 0 (Ω) × H 1 0 (Ω) × U ad satisfies the Karush-Kuhn-Tucker (KKT) optimality conditions [30,Theorem 1.4]:
a(y, w) = (f + u, w) ∀ w ∈ H 1 0 (Ω), (1.4a) a(w, p) = (y − y d , w) ∀ w ∈ H 1 0 (Ω), (1.4b) (p + α(u − u d ), v − u) ≥ 0 ∀ v ∈ U ad . (1.4c) 1.2.
Two particular cases of our main results. Our analysis of numerical methods for (1.4) is based on the abstract framework of the gradient discretisation method. To give an idea of the extent of our main results, let us consider two particular schemes, based on a mesh T of Ω. We assume here that U ad = {v ∈ L 2 (Ω) : a ≤ v ≤ b a.e.} for some constants a, b (possibly infinite) and, to simplify the presentation, that u d = 0. Set P [a,b] (s) = min(b, max(a, s)). Let u be a postprocessed control, whose scheme-dependent definition is given below.
• ncP 1 /P 0 : T is a conforming triangular/tetrahedral mesh, the state and adjoint unknowns (y, p) are approximated using non-conforming P 1 finite elements, and the control u is approximated using piecewise constant functions on T . We then let the post-processed continuous control be u = u. • hMFD [1]: T is a polygonal/polyhedral mesh, the state and adjoint unknowns (y, p) are approximated using mixed-hybrid mimetic finite differences (hMFD), and the control u is approximated using piecewise constant functions on T . The hMFD schemes form a sub-class of the hybrid mimetic mixed (HMM) methods [17,18] presented in the appendix (Section 7.1); see also Section 6 for corresponding numerical tests. We then define a post-processed continuous control u by
u |K = P [a,b] (−α −1 p(x K )) for all K ∈ T ,
where x K denotes the centroid of the cell K. In either case, the post-processed discrete control is u h = P [a,b] (−α −1 p h ), where p h denotes the discrete co-state. One of the consequences of our first main theorem is the following super-convergence result on the control, under standard regularity assumptions on the mesh and the data: there exists C that depends only on Ω, A, α, a, b, u, and the shape regularity of T , such that
u − u h ≤ Ch r (1 + y d H 1 (Ω) + f H 1 (Ω) + u d H 2 (Ω) ),(1.5)
where r = 2 − (for any > 0) if n = 2, and r = 11 6 if n = 3. This estimate is also valid for conforming P 1 finite elements. Under the additional assumption of quasi-uniformity of the mesh (that is, each cell has a measure comparable to h n ), our second main theorem shows that (1.5) can be improved into a full quadratic rate of convergence:
u − u h ≤ Ch 2 (1 + y d H 1 (Ω) + f H 1 (Ω) + u d H 2 (Ω) ).
(1.6)
The quasi-uniformity assumption prevents us from considering local mesh refinement, so (1.6) is not ensured in these cases. On the contrary, the rate (1.5) still holds true for locally refined meshes. Moreover, in dimension n = 2, the h 2− rate in (1.5) is numerically indistinguishable from a full super-convergence h 2 rate. If n = 3, the h 11 6 rate of convergence remains very close to h 2 . To compare, for h = 10 −6 (which is well below the usual mesh sizes in 3D computational tests) we have h 2 /h 11 6 = 10 −1 . Precise statement of the assumptions and the proofs of (1.5) and (1.6) are given in Corollary 3.8.
The gradient discretisation method for the control problem
The gradient discretisation method (GDM) consists in writing numerical schemes, called gradient schemes (GS), by replacing in the weak formulation of the problem the continuous space and operators by discrete ones [16,18,23]. These discrete space and operators are given by a gradient discretisation (GD).
Definition 2.1 (Gradient discretisation for homogeneous Dirichlet BC). A gradient discretisation for homogeneous Dirichlet BC is given by D = (X D,0 , Π D , ∇ D ) such that
• the set of discrete unknowns (degrees of freedom) X D,0 is a finite dimensional real vector space, • Π D : X D,0 → L 2 (Ω) is a linear mapping that reconstructs a function from the degrees of freedom, • ∇ D : X D,0 → L 2 (Ω) n is a linear mapping that reconstructs a gradient from the degrees of freedom. It must be chosen such that ∇ D · is a norm on X D,0 .
Let D = (X D,0 , Π D , ∇ D ) be a GD in the sense of the above definition. If F ∈ L 2 (Ω), then the related gradient scheme for a linear elliptic problem
−div(A∇ψ) = F in Ω, ψ = 0 on ∂Ω (2.1)
is obtained by writing the weak formulation of (2.1) with the continuous spaces, function and gradient replaced with their discrete counterparts:
Find ψ D ∈ X D,0 such that, for all w D ∈ X D,0 , a D (ψ D , w D ) = (F, Π D w D ), (2.2) where a D (ψ D , w D ) = Ω A∇ D ψ D · ∇ D w D dx.
Remark 2.2. The inclusion of a scheme S for (2.1) into the GDM consists in finding a suitable gradient discretisation D such that S is algebraically identical to (2.2). We refer to [19] for the proofs that various classical methods fit into the GDM.
Let U h be a finite-dimensional subspace of L 2 (Ω), and U ad,h = U ad ∩ U h . A gradient discretisation D being given, the corresponding GS for (1.4) consists in seeking
(y D , p D , u h ) ∈ X D,0 × X D,0 × U ad,h such that a D (y D , w D ) = (f + u h , Π D w D ) ∀ w D ∈ X D,0 , (2.3a) a D (w D , p D ) = (Π D y D − y d , Π D w D ) ∀ w D ∈ X D,0 , (2.3b) (Π D p D + α(u h − u d ), v h − u h ) ≥ 0 ∀ v h ∈ U ad,h . (2.3c)
Arguing as in [36,Theorem 2.25], it is straightforward to see that (2.3) is equivalent to the following minimisation problem:
min u h ∈U ad,h 1 2 Π D y D − y d 2 + α 2 u h − u d 2 subject to y D ∈ X D,0 and, for all w D ∈ X D,0 , a D (y D , w D ) = (f + u h , Π D w D ).
(2.4)
Existence and uniqueness of a solution to (2.4), and thus to (2.3), follows from standard variational theorems.
2.1. Results on the GDM for elliptic PDEs. We recall here basic notions and known results on the GDM for elliptic PDEs. The accuracy of a GS (2.2) is measured by three quantities. The first one, which ensures the coercivity of the method, controls the norm of Π D .
C D := max w∈X D,0 \{0} Π D w ∇ D w . (2.5)
The second measure involves an estimate of the interpolation error, called the GDconsistency (or consistency, for short) in the framework of the GDM. It corresponds to the interpolation error in the finite elements nomenclature.
∀ϕ ∈ H 1 0 (Ω), S D (ϕ) = min w∈X D,0 ( Π D w − ϕ + ∇ D w − ∇ϕ ) . (2.6)
Finally, we measure the limit-conformity of a GD by defining
∀ϕ ∈ H div (Ω), W D (ϕ) = max w∈X D,0 \{0} 1 ∇ D w W D (ϕ, w) ,(2.7)
where H div (Ω) = {ϕ ∈ L 2 (Ω) n : div(ϕ) ∈ L 2 (Ω)} and
W D (ϕ, w) = Ω (Π D w div(ϕ) + ∇ D w · ϕ) dx. (2.8)
We use the following notation. X Y means that X ≤ CY for some C depending only on Ω, A and an upper bound of C D .
(2.9)
The following basic error estimate on GSs is standard, see [16,Theorem 3.2].
Theorem 2.3. Let D be a GD in the sense of Definition 2.1, ψ be the solution to (2.1), and ψ D be the solution to (2.2). Then
Π D ψ D − ψ + ∇ D ψ D − ∇ψ WS D (ψ), (2.10) where WS D (ψ) = W D (A∇ψ) + S D (ψ) (2.11) S D is defined by (2.6) and W D is defined by (2.7).
Remark 2.4 (Rates of convergence for the PDE). For all classical first-order methods based on meshes with mesh parameter "h", O(h) estimates can be obtained for W D (A∇ψ) and S D (ψ), if A is Lipschitz continuous and ψ ∈ H 2 (Ω) (see [16,Chapter 8]). Theorem 2.3 then gives a linear rate of convergence for these methods.
Main results: basic error estimate and super-convergence
In this section, the main contributions are stated and the assumptions are discussed in details. The proofs of the results are presented in Section 4.
3.1.
Basic error estimate for the GDM for the control problem. To state the error estimates, let Pr h : L 2 (Ω) → U h be the L 2 orthogonal projector on U h for the standard scalar product.
Theorem 3.1 (Control estimate). Let D be a GD, (y, p, u) be the solution to (1.4) and (y D , p D , u h ) be the solution to (2.3). We assume that
Pr h (U ad ) ⊂ U ad,h . (3.1) Then, √ α u − u h √ α α −1 p − Pr h (α −1 p) + ( √ α + 1) u − Pr h u + √ α u d − Pr h u d + 1 √ α WS D (p) + WS D (y). (3.2)Π D y D − y + ∇ D y D − ∇y u − u h + WS D (y), (3.3) Π D p D − p + ∇ D p D − ∇p u − u h + WS D (y) + WS D (p). (3.4)
3.2.
Super-convergence for post-processed controls. We consider here the case n ≤ 3, and the standard situation where admissible controls are those bounded above and below by appropriate constants a and b, that is
U ad = {u ∈ L 2 (Ω) : a ≤ u ≤ b a.e.}. (3.5)
Consider a mesh T of Ω, that is a finite partition of Ω into polygonal/polyhedral cells such that each cell K ∈ T is star-shaped with respect to its centroid x K . Denote the size of this mesh by h = max K∈T diam(K). The discrete space U h is then defined as the space of piecewise constant functions on this partition:
U h = {v : Ω → R : ∀K ∈ T , v |K is a constant}. (3.6)
These choices (3.5) and (3.6) of U ad and U h satisfy (3.1). Owing to Remark 3.3, for low-order methods such as conforming and non-conforming FE or MFD schemes, under standard regularity assumptions the estimate (3.2) provides an O(h) convergence rate on u − u h . Given that u h is piecewise constant, this is optimal. However, using post-processed controls and following the ideas of [34], we show that we can obtain a super-convergence result for the control.
The projection operators P T :
L 1 (Ω) → U h (orthogonal projection on piecewise constant functions on T ) and P [a,b] : R → [a, b] are defined as ∀v ∈ L 1 (Ω) , ∀K ∈ T , (P T v) |K := − K v(x)dx
and ∀s ∈ R , P [a,b] (s) := min(b, max(a, s)). We make the following assumptions which are discussed, along with the postprocessing, in Section 3.2.1.
(A1) [Approximation and interpolation errors]
For each w ∈ H 2 (Ω), there exists w T ∈ L 2 (Ω) such that: i) If w ∈ H 2 (Ω) ∩ H 1 0 (Ω) solves −div(A∇w) = g ∈ H 1
(Ω), and w D is the solution to the corresponding GS, then
Π D w D − w T h 2 g H 1 (Ω) . (3.7) ii) For any w ∈ H 2 (Ω), it holds ∀v ∈ X D,0 , (w − w T , Π D v D ) h 2 w H 2 (Ω) Π D v D (3.8)
and
P T (w − w T ) h 2 w H 2 (Ω) . (3.9) (A2) The estimate Π D v D − P T (Π D v D ) h ∇ D v D holds for any v D ∈ X D,0 . (A3) [Discrete Sobolev imbedding] For all v ∈ X D,0 , it holds Π D v D L 2 * (Ω) ∇ D v D , where 2 * is a Sobolev exponent of 2, that is, 2 * ∈ [2, ∞) if n = 2, and 2 * = 2n n−2 if n ≥ 3. Let T 2 = {K ∈ T : u = a a.e. on K, or u = b a.e. on K, or a < u < b a.e. on K}
be the set of fully active or fully inactive cells, and T 1 = T \ T 2 be the set of cells where u takes on the value a (resp. b) as well as values greater than a (resp. lower than b). For i = 1, 2, we let Ω i,T = int(∪ K∈Ti K). The space W 1,∞ (T 1 ) is the usual broken Sobolev space, endowed with its broken norm. Our last assumption is:
(A4) |Ω 1,T | h and u |Ω 1,T ∈ W 1,∞ (T 1 ), where |·| denotes the Lebesgue measure in R n .
From (1.4c) and (2.3c), following the reasoning in [36, Theorem 2.28], the following pointwise relations can be obtained: for a.e. x ∈ Ω,
u(x) = P [a,b] u d (x) − 1 α p(x) , u h (x) = P [a,b] P T u d (x) − 1 α Π D p D (x) .
(3.10)
Assuming p ∈ H 2 (Ω) (see Theorem 3.4) and letting p T be defined as in (A1), the post-processed continuous and discrete controls are then defined by
u(x) = P [a,b] P T u d (x) − 1 α p T (x) , u h (x) = P [a,b] P T u d (x) − 1 α Π D p D (x) .
(3.11)
For K ∈ T , let ρ K = max{r > 0 : B(x K , r) ⊂ K} be the maximal radius of balls centred at x K and included in K. Assume that the mesh is regular, in the sense that there exists η > 0 such that
∀K ∈ T , η ≥ diam(K) ρ K . (3.12)
We use the following extension of the notation (2.9):
X η Y means that X ≤ CY for some C depending only on Ω, A, an upper bound of C D , and η.
We now state our two main super-convergence results.
Theorem 3.4 (Super-convergence for post-processed controls I). Let D be a GD and T be a mesh. Assume that • U ad and U h are given by (3.5) and (3.6),
• (A1)-(A4) hold,
• u d , y and p belong to H 2 (Ω),
• y d and f belong to H 1 (Ω), and let u, u h be the post-processed controls defined by (3.11). Then there exists C depending only on α such that there exists δ > 0 such that, for any F ∈ L 2 (Ω),
u − u h η Ch 2− 1 2 * u W 1,∞ (T1) + Ch 2 F(a, b, y d , u d , f, y, p), (3.13) where F(a, b, y d , u d , f, y, p) = minmod(a, b) + y d H 1 (Ω) + u d H 2 (Ω) + f H 1 (Ω) + y H 2 (Ω) + p H 2 (Ω) with minmod(a, b) = 0 if ab ≤ 0 and minmod(a, b) = min(|a|, |b|) otherwise.the solution ψ D to (2.2) satisfies Π D ψ D L ∞ (Ω) ≤ δ F . (3.14)
Then there exists C depending only on α and δ such that
u − u h η Ch 2 u W 1,∞ (T1) + F(a, b, y d , u d , f, y, p) . (3.15)
Remark 3.6. The estimates (3.13) and (3.15) also hold if we replace the two terms
P T u d in (3.11) with u d .
The super-convergence of the state and adjoint variables follow easily.
y T − Π D y D η Ch r u W 1,∞ (T1) + Ch 2 F(a, b, y d , u d , f, y, p), (3.16) p T − Π D p D η Ch r u W 1,∞ (T1) + Ch 2 F(a, b, y d , u d , f, y, p), (3.17)
where y T and p T are defined as in (A1), and r = 2 − 1 2 * . Under the assumptions of Theorem 3.5, (3.16) and (3.17) hold with r = 2 and C depending only α and δ.
Even for very classical schemes, the L ∞ estimate (3.14) is only known under restrictive assumptions on the mesh. For example, for conforming and non-conforming P 1 finite elements, it requires the quasi-uniformity of the mesh [25], which prevents considering local refinements widely used in practical applications. The scope of Theorem 3.5 is therefore limited in that sense, but it nonetheless extends to various methods (see e.g. Corollary 3.8) the super-convergence established in [34] for conforming P 1 finite elements. On the contrary, Theorem 3.4 holds under much less restrictive assumptions (see below for a discussion of (A1)-(A4)), and applies seamlessly to locally refined meshes, for essentially all numerical methods currently covered by the GDM. It is also useful to notice that Theorem 3.4 nearly provides an h 2 convergence rate. If n = 2, the Sobolev exponent 2 * can be any finite number. In that case, (3.13), (3.16) and (3.17) are O(h 2− ) estimates, for any > 0. If n = 3, the estimates are of order O(h 11/6 ). In each case, as noticed in Section 1.2, these rates are numerically very close to a full O(h 2 ) convergence rate. Π D is a piecewise linear reconstruction. We consider here the case where Π D v D is piecewise linear on T for all v D ∈ X D,0 . Then a super-convergence result (3.7) usually holds with w T = w (and even g instead of g H 1 (Ω) ). This is for example well-known for conforming and non-conforming P 1 FE. In that case, (3.8) and (3.9) are trivially satisfied. Assumption (A2) then follows from a simple Taylor expansion if ∇ D v D is the classical broken gradient (i.e. the gradient of Π D v D in each cell). This is again the case for conforming and non-conforming P 1 FE. The post-processing (3.11) of u then solely consists in projecting u d on piecewise constant functions. In particular, if u d is already piecewise constant on the mesh, then u = u.
Π D is a piecewise constant reconstruction. We consider that Π D v D is piecewise constant on T for all v D ∈ X D,0 . Then the super-convergence (3.7) requires to project the exact solution on piecewise constant functions on the mesh. This is usually done by setting w T (x) = w(x K ) for all x ∈ K and all K ∈ T . This super-convergence result is well-known for hMFD and nodal MFD schemes (see [6,21]). In that case, Property (3.9) follows (with replaced with η ) from the classical approximation result (4.20). Using the orthogonality property of P T , (3.8) is then proved by writing
|(w − w T , Π D v D )| = |(P T (w − w T ), Π D v D )| ≤ P T (w − w T ) Π D v D η h 2 w H 2 (Ω) Π D v D . For a piecewise constant reconstruction, (A2) is trivial since Π D v D = P T (Π D v D ).
Assumptions (A3) and (A4). Using the discrete functional analysis tools of [16,Chapter 8] the discrete Sobolev embedding (A3) is rather straightforward for all methods that fit in the GDM. This includes conforming and non-conforming P 1 schemes as well as MFD schemes. Assumption (A4) is identical to the assumption (A3) in [34]. Let R be the region where the bounds a and b pass from active to inactive, i.e. where u d − α −1 p crosses these bounds. If R is of co-dimension 1, which is a rather natural situation, then the condition |Ω 1,T | h holds.
The W 1,∞ regularity on u mentioned in (A4) can be established in a number of situations. It holds, for example, if Ω is a bounded open subset of class C 1,1 , the coefficients of A belong to C 0,1 (Ω), u d ∈ W 1,∞ (Ω) and y d ∈ L q (Ω) for some q > n. Indeed, under these assumptions, [26,Theorem 2.4.2.5] ensures that the state and adjoint equations admit unique solutions in H 1 0 (Ω)∩W 2,q (Ω) ⊂ W 1,∞ (Ω). The projection formula (3.10) then shows that u inherits this Lipschitz continuity property over Ω. This also holds if Ω has corners but adequate symmetries (that preserve the W 2,q (Ω) regularity). Assumption (A4) actually does not require the full W 1,∞ regularity of u, only this regularity on a neighbourhood of R. Considering a generic open set Ω with Lipschitz (but not necessarily smooth) boundary, [35,Theorem 7.3] ensures that p is continuous. If u d is continuous and a < (u d ) |∂Ω < b, then u d − α −1 p does not cross the levels a and b close to ∂Ω, which means that R is a compact set inside Ω. The Lipschitz regularity of u then follows, under the same assumptions on A, u d and y d as above, from local regularity results (internal to Ω), without assuming that the boundary of Ω is C 1,1 . In all these cases, we also notice that, although the mesh T depends on h, the norm u W 1,∞ (T1) remains bounded independently on h → 0. Indeed, this norm is bounded by a Lipschitz constant of u on a neighbourhood of R.
3.2.2.
Application to non-conforming P 1 and hMFD. Our generic results on the GDM apply to all methods covered by this framework. In particular, as mentioned in Section 1.2, to non-conforming P 1 finite elements and hMFD methods. We state here a corollary of the super-convergence results on the control (Theorems 3.4 and 3.5) for these two methods. We could as easily state obvious consequence for these two schemes of Theorem 3.1, Proposition 3.2 and Corollary 3.7.
Corollary 3.8 (Super-convergence of the control for ncP 1 and hMFD schemes). Assume that Ω is convex and A is Lipschiz-continuous. Let T be a mesh in the sense of [19,Definition 2.21], with centers at the centers of mass of the cells. Assume U ad and U h are given by (3.5) and (3.6), (A4) holds, u d ∈ H 2 (Ω) and that (y d , f ) ∈ H 1 (Ω). We consider either one of the following schemes, as described in Section 1.2, with associated post-processed controls (here, (y h , p h , u h ) is the solution to the scheme for the control problem):
• ncP 1 /P 0 scheme: η satisfies (3.12), u = P [a,b] (P T u d − α −1 p), and u h = P [a,b] (P T u d − α −1 p h ).u |K = P [a,b] − K u d − α −1 p(x K ) and ( u h ) |K = P [a,b] − K u d − α −1 (p h ) K .
Then there exists C depending only on Ω, A, α, a, b, u, u d , y d , f and η such that
u − u h ≤ Ch 2− 1 2 * . (3.18)
Moreover, if χ ≥ max K∈T h n |K| , then there exists C depending only on Ω, A, α, a, b, u, u d , y d , f , η and χ such that
u − u h ≤ Ch 2 . (3.19)
Remark 3.9. The conforming P 1 FE method is a GDM for the gradient discretisation defined by D = (V h , Id, ∇), where V h is the conforming P 1 space on the considered mesh. Then, W D ≡ 0 and S D is bounded above by the interpolation error of the P 1 method. For this gradient discretisation method, Theorems 3.1 and 3.5 provide, respectively, O(h) error estimates on the control and O(h 2 ) error estimates on the post-processed controls (under a quasi-uniformity assumption on the sequence of meshes). These rates are the same already proved in [34]. For ncP 1 FE method, the estimate (3.19) provides quadratic rate of convergence in a similar way as for conforming P 1 method.
Proof of Corollary 3.8. [19, Sections 3.2.1 and 3.6.1] presents a description of the GDs corresponding to the ncP 1 and hMFD schemes (the latter is seen as a GS through its identification as a hybrid mimetic mixed method, see [17,18]; the corresponding GD is recalled in Section 7.1, Appendix). Using these gradient discretisations, (3.18) follows from Theorem 3.4 if we can prove that (A1)-(A3) hold, for a proper choice of operator w → w T . Note that our assumptions on Ω and A ensure that the state (and thus adjoint) equations satisfy the elliptic regularity: if the source terms are in L 2 (Ω) then the solutions belong to H 2 (Ω). For the ncP 1 scheme, recall that w T = w and the superconvergence result (3.7)
is known under the elliptic regularity. Also, Π D w D is simply the solution w h to the scheme. Properties (3.8) and (3.9) are obvious since w − w T = 0. This proves (A1). Assumption (A2) follows easily from a Taylor expansion since ∇ D v D is the broken gradient of Π D v D . Assumption (A3) follows from [13,Proposition 5.4], by noticing that for piecewise polynomial functions that match at the face centroids, the discrete · 1,2,h norm in [13] boils down to the L 2 (Ω) n norm of the broken gradient.
We now consider the hMFD scheme, for which we let (w T ) |K = w(x K ) for all K ∈ T . The super-convergence result of (A1)-i) is proved in, e.g., [7,21]. As mentioned in Section 3. The full super-convergence result (3.19) follows from Theorem 3.5 if we can establish the L ∞ bound (3.14) under the assumption that χ is bounded -i.e. the mesh is quasi-uniform. This L ∞ bound is known for the ncP 1 finite element method [25], and is proved in Theorem 7.1 for the HMM method.
Proof of the main results
4.1.
Proof of the basic error estimates. Let us start with a straightforward stability result, which will be useful for the analysis.
∇ D ψ D ≤ C D a F and Π D ψ D ≤ C 2 D a F . (4.1)
Proof. Choose w D = ψ D in (2.2) and use the definition of C D to write
a ∇ D ψ D 2 ≤ F Π D ψ D ≤ C D F ∇ D ψ D .
The proof of first inequality in (4.1) is complete. The second estimate follows from the definition of C D .
We can now prove Theorem 3.1. The technique used here is an adaptation of classical ideas used (e.g., for the error-analysis of finite-element based discretisations) to the gradient discretisation method. In this proof, define the scaled norm |||·||| and projection error E h by
∀W ∈ L 2 (Ω) , |||W ||| = √ α W and E h (W ) = |||W − Pr h W |||.
To establish the error estimates, we need the following auxiliary discrete problem:
seek (y D (u), p D (u)) ∈ X D,0 × X D,0 such that a D (y D (u), w D ) = (f + u, Π D w D ) ∀ w D ∈ X D,0 , (4.2a) a D (w D , p D (u)) = (y − y d , Π D w D ) ∀ w D ∈ X D,0 . (4.2b) Proof of Theorem 3.1. Let P D,α (u) = α −1 Π D p D (u), P D,α = α −1 Π D p D , and P α = α −1 p. Since u h ∈ U ad,h ⊂ U ad , from the optimality condition (1.4c), − α(P α + u − u d , u − u h ) ≥ 0. (4.3)
By (3.1), we have Pr h u ∈ U ad,h and therefore a use of the discrete optimality condition (see (2.3c)) yields
α(P D,α + u h − u d , u − u h ) = α(P D,α + u h − u d , u − Pr h u) + α(P D,α + u h − u d , Pr h u − u h ) ≥ α(P D,α + u h − u d , u − Pr h u). (4.4)
An addition of (4.3) and (4.4) yields
|||u − u h ||| 2 ≤ − α(P D,α + u h − u d , u − Pr h u) + α(P D,α − P α , u − u h ) = − α(P D,α + u h − u d , u − Pr h u) − α(P α − P D,α (u), u − u h ) + α(P D,α − P D,α (u), u − u h ). (4.5)
The first term in the right-hand side of (4.5) is recast now. By orthogonality property of Pr h we have (u h − Pr h u d , u − Pr h u) = 0 and (Pr h P α , u − Pr h u) = 0. Therefore,
−α(P D,α + u h − u d , u − Pr h u) = − α(P α , u − Pr h u) + α(P α − P D,α , u − Pr h u) − α(Pr h u d − u d , u − Pr h u) = − α(P α − Pr h P α , u − Pr h u) + α(P α − P D,α (u), u − Pr h u) + α(P D,α (u) − P D,α , u − Pr h u) + α(u d − Pr h u d , u − Pr h u). (4.6)
Let us turn to the third term in the right-hand side of (4.5). From (2.3b) and (4.2b), for all w D ∈ X D,0 ,
a D (w D , p D − p D (u)) = (Π D y D − y, Π D w D ). (4.7)
We also have, by (2.3a) and (4.2a),
a D (y D − y D (u), w D ) =(u h − u, Π D w D ). (4.8)
A use of symmetry of a D , a choice of w D = y D −y D (u) in (4.7) and w D = p D −p D (u) in (4.8) gives an expression for the third term on the right hand side of (4.5) as
α(P D,α − P D,α (u), u − u h ) = − (Π D y D − y, Π D y D − Π D y D (u)) = (y − Π D y D (u), Π D y D − Π D y D (u)) − Π D y D − Π D y D (u) 2 . (4.9)
A substitution of (4.6) and (4.9) in (4.5) yields
|||u − u h ||| 2 + Π D y D − Π D y D (u) 2 ≤ −α(P α − Pr h P α , u − Pr h u) + α(P α − P D,α (u), u − Pr h u) + α(P D,α (u) − P D,α , u − Pr h u) + α(u d − Pr h u d , u − Pr h u) − α(P α − P D,α (u), u − u h ) + (y − Π D y D (u), Π D y D − Π D y D (u)) =: T 1 + T 2 + T 3 + T 4 + T 5 + T 6 .
(4.10)
We now estimate each term T i , i = 1, . . . , 6. By Cauchy-Schwarz inequality we have
T 1 ≤ E h (P α )E h (u). (4.11)
Equation (4.2b) shows that p D (u) is the solution of the GS corresponding to the adjoint problem (1.4b), whose solution is p. Therefore, by Theorem 2.3,
P α − P D,α (u) = 1 √ α p − Π D p D (u) 1 √ α WS D (p). (4.12)
Hence, using the Cauchy-Schwarz inequality,
T 2 1 √ α E h (u)WS D (p). (4.13)
Let us turn to T 3 . By writing the difference of (4.2b) and (2.3b) we see that p D (u) − p D is the solution to the GS (2.2) with source term F = y − Π D y D . Hence, using Proposition 4.1, we find that
P D,α (u) − P D,α = 1 √ α Π D p D (u) − Π D p D 1 √ α y − Π D y D 1 √ α y − Π D y D (u) + 1 √ α Π D y D (u) − Π D y D .
A use of Theorem 2.3 with ψ = y to bound the first term in the above expression yields, by Young's inequality,
T 3 ≤ C 1 √ α E h (u)WS D (y) + C 1 α E h (u) 2 + 1 4 Π D y D (u) − Π D y D 2 ,(4.14)
where C 1 only depends on Ω, A and an upper bound of C D . Let us consider T 4 now. A use of Cauchy-Schwarz inequality and Young inequality leads to
T 4 ≤ E h (u)E h (u d ) ≤ 1 2 E h (u) 2 + 1 2 E h (u d ) 2 . (4.15)
We estimate T 5 by using (4.12) and Young's inequality:
T 5 ≤ 1 2 |||u − u h ||| 2 + C 2 α WS D (p) 2 ,(4.16)
where C 2 only depends on Ω, A and an upper bound of C D . Finally, to estimate T 6 we write, by Theorem 2.3 with ψ = y,
T 6 ≤ C 3 WS D (y) Π D y D − Π D y D (u) ≤ C 2 3 WS D (y) 2 + 1 4 Π D y D − Π D y D (u) 2 ,(4.17)
with C 3 only depending on Ω, A and an upper bound of C D . We then plug (4.11), (4.13), (4.14), (4.15), (4.16) and (4.17) into (4.10). A use of Young's inequality and i a 2 i ≤ i a i concludes the proof. 4.2. Proof of the super-convergence estimates. The following auxiliary problem will be useful to prove the superconvergence of the control. For g ∈ L 2 (Ω), let
p * D (g) ∈ X D,0 solve a D (w D , p * D (g)) = (Π D y D (g) − y d , Π D w D ) ∀w D ∈ X D,0 ,(4.18)
where y D (g) is given by (4.2a) with u replaced by g. Let us recall two approximation properties of P T . As proved in [16,Lemma 8.10],
∀φ ∈ H 1 (Ω) , P T φ − φ η h φ H 1 (Ω) . (4.19)
For K ∈ T , let x K be the centroid (centre of gravity) of K. We have the standard approximation property (see e.g. [21, Lemma 7.7] with w K ≡ 1)
∀K ∈ T , ∀φ ∈ H 2 (K) , P T φ − φ(x K ) L 2 (K) η diam(K) 2 φ H 2 (K) . (4.20)
Proof of Theorem 3.4. Define u, p and u d a.e. on Ω by: for all K ∈ T and all x ∈ K, u(x) = u(x K ), p(x) = p(x K ) and u d (x) = u d (x K ). From (3.11) and the Lipschitz continuity of P [a,b] , it follows that
u − u h ≤ α −1 Π D p D − p T ≤ α −1 p T − Π D p * D (u) + α −1 Π D p * D (u) − Π D p * D ( u) + α −1 Π D p * D ( u) − Π D p D =: α −1 A 1 + α −1 A 2 + α −1 A 3 .
(4.21)
Step 1: estimate of A 1 .
Recalling the equations (1.4b) and (4.2b) on p and p D (u), a use of triangle inequality and (A1)-i) yields
A 1 ≤ p T − Π D p D (u) + Π D p D (u) − Π D p * D (u) h 2 y − y d H 1 (Ω) + Π D p D (u) − Π D p * D (u) .(4.22)
We now estimate the last term in this inequality. Subtract (4.18) with g = u from (4.2b), substitute w D = p D (u) − p * D (u) , use Cauchy-Schwarz inequality and property (3.8)
in (A1)-ii) to obtain ∇ D (p D (u) − p * D (u)) 2 a D (p D (u) − p * D (u), p D (u) − p * D (u)) = (y − Π D y D (u), Π D (p D (u) − p * D (u))) = (y − y T , Π D (p D (u) − p * D (u))) + (y T − Π D y D (u), Π D (p D (u) − p * D (u))) h 2 y H 2 (Ω) Π D (p D (u) − p * D (u)) + y T − Π D y D (u) Π D (p D (u) − p * D (u)) .
Using the definition of C D and (A1)-i) leads to Π
D p D (u)−Π D p * D (u) h 2 y H 2 (Ω) + h 2 f + u H 1 (Ω) .
Plugged into (4.22), this estimate yields
A 1 h 2 ( y − y d H 1 (Ω) + y H 2 (Ω) + f + u H 1 (Ω) ).
(4.23)
Step 2: estimate of A 2 . Subtracting the equations (4.18) satisfied by p * D (u) and p *
D ( u), for all v D ∈ X D,0 , a D (v D , p * D (u) − p * D ( u)) = (Π D y D (u) − Π D y D ( u), Π D v D ). (4.24)
As a consequence of (4.24) and Proposition 4.1,
A 2 = Π D p * D (u) − Π D p * D ( u) Π D y D (u) − Π D y D ( u) . (4.25) Choosing v D = y D (u) − y D ( u) in (4.24), setting w D = p * D (u) − p * D ( u)
, subtracting the equations (4.2a) satisfied by y D (u) and y D ( u), using the orthogonality property of the projection operator P T , and invoking (4.19) and (A2) gives
Π D (y D (u) − y D ( u)) 2 = (Π D y D (u) − Π D y D ( u), Π D y D (u) − Π D y D ( u)) = a D (y D (u) − y D ( u), p * D (u) − p * D ( u)) = (u − u, Π D w D ) = (u − P T u, Π D w D − P T (Π D w D )) + (P T u − u, Π D w D ) η h u H 1 (Ω) h ∇ D w D + Ω 1,T (P T u − u)Π D w D dx A21 + Ω 2,T (P T u − u)Π D w D dx A22 .
(4.26)
Equation (4.24) and Proposition 4.1 show that
∇ D w D = ∇ D (p * D (u) − p * D ( u)) Π D (y D (u) − y D ( u)) . (4.27)
Plugging this estimate into (4.26) yields
Π D (y D (u) − y D ( u)) 2 η h 2 u H 1 (Ω) Π D (y D (u) − y D ( u)) + A 21 + A 22 . (4.28)
A use of Holder's inequality, (A4), (A3) and (4.27) yields
A 21 ≤ P T u − u L 2 (Ω 1,T ) Π D w D L 2 (Ω 1,T ) ≤ h u W 1,∞ (T1) |Ω 1,T | 1 2 Π D w D L 2 * (Ω) |Ω 1,T | 1 2 − 1 2 * h 2− 1 2 * u W 1,∞ (T1) ∇ D w D h 2− 1 2 * u W 1,∞ (T1) Π D (y D (u) − y D ( u)) . (4.29)
Consider now A 22 . For any K ∈ T 2 , we have u = a on K, u = b on K, or, by (3.10), u = u d − α −1 p. Hence, u ∈ H 2 (K) and, using (4.20), the definition of C D and (4.27), we obtain
A 22 ≤ P T u − u L 2 (Ω 2,T ) Π D w D η h 2 u H 2 (Ω 2,T ) Π D w D η h 2 u d H 2 (Ω 2,T ) + α −1 p H 2 (Ω 2,T ) ∇ D w D η h 2 u d H 2 (Ω 2,T ) + α −1 p H 2 (Ω 2,T ) Π D (y D (u) − y D ( u)) . (4.30)
Plugging (4.29) and (4.30) into (4.28) yields
Π D (y D (u) − y D ( u)) η h 2 u H 1 (Ω) + h 2− 1 2 * u W 1,∞ (T1) + h 2 u d H 2 (Ω 2,T ) + α −1 p H 2 (Ω 2,T ) .
(4.31)
Hence, using this in (4.25), we infer
A 2 η h 2− 1 2 * u W 1,∞ (T1) + h 2 ( u H 1 (Ω) + α −1 p H 2 (Ω) + u d H 2 (Ω) ). (4.32)
Step 3: estimate of A 3 . Applying twice the stability result of Proposition 4.1 (first on the equation satisfied by p * D ( u) − p D , and then on y D ( u) − y D ), we write
A 3 = Π D p * D ( u) − Π D p D Π D y D ( u) − Π D y D u − u h . (4.33)
Using the continuous optimality condition (1.4c), as in the proof of [34,Lemma 3.5] we have, for a.e. x ∈ Ω,
p(x) + α(u(x) − u d (x)) v(x) − u(x) ≥ 0 for all v ∈ U ad .
Since u, p and u h are continuous at the centroid x K , we can choose
x = x K and v(x K ) = u h (x K )(= u h on K)
. All the involved functions being constants over K, this gives
( p + α( u − u d )) (u h − u) ≥ 0 on K, for all K ∈ T .
Integrating over K and summing over K ∈ T ,
( p + α ( u − u d ) , u h − u) ≥ 0.
Choose v h = u in the discrete optimality condition (2.3c) to obtain
(Π D p D + α(u h − u d ), u − u h ) ≥ 0.
Adding the above two inequalities yield
( p − Π D p D + α( u − u h ) + α(u d − u d ), u h − u) ≥ 0 and thus α u − u h 2 ≤ ( p − Π D p D , u h − u) + α(u d − u d , u h − u) = ( p − p T , u h − u) + (p T − Π D p * D ( u), u h − u) + (Π D p * D ( u) − Π D p D , u h − u) + α(u d − u d , u h − u) =: M 1 + M 2 + M 3 + M 4 .
(4.34)
Since u h − u is piecewise constant on T , the orthogonality property of P T , (4.20) and (3.9) in (A1)-ii) lead to
M 1 = ( p − P T p T , u h − u) = ( p − P T p, u h − u) + (P T (p − p T ), u h − u) ≤ p − P T p u h − u + P T (p − p T ) u h − u η h 2 p H 2 (Ω) u h − u . (4.35)
By Cauchy-Schwarz inequality, triangle inequality and the definitions of A 1 and A 2 ,
M 2 ≤ p T − Π D p * D ( u) u h − u (A 1 + A 2 ) u h − u .M 3 = (Π D (p * D ( u) − p D ), u h − u) = a D (y D − y D ( u), p * D ( u) − p D ) = (Π D (y D ( u) − y D ), Π D (y D − y D ( u)) ≤ 0.
(4.37)
Using the orthogonality property of P T , (4.20) yields
M 4 = α(u d − u d , u h − u) = α(P T u d − u d , u h − u) η α P T u d − u d u h − u η αh 2 u d H 2 (Ω) u h − u .A 3 u h − u η α −1 h 2− 1 2 * u W 1,∞ (T1) + α −1 h 2 y − y d H 1 (Ω) + y H 2 (Ω) + (1 + α −1 ) p H 2 (Ω) + f + u H 1 (Ω) + u H 1 (Ω) + (1 + α) u d H 2 (Ω) .
(4.39)
Step 4: conclusion. It is easy to check that |P [a,b] (s)| ≤ minmod(a, b) + |s|, where minmod is defined in Theorem 3.4. Hence, by (3.10) and Lipschitz continuity of P [a,b] ,
u H 1 (Ω) ≤ P [a,b] u d − α −1 p L 2 (Ω) + ∇ P [a,b] u d − α −1 p L 2 (Ω) n ≤ minmod(a, b)|Ω| 1/2 + 2 u d − α −1 p H 1 (Ω) ≤ minmod(a, b)|Ω| 1/2 + 2 u d H 1 (Ω) + 2α −1 p H 1 (Ω) .
(4.40)
Using this inequality and inserting (4.23), (4.32) and (4.39) in (4.21), the proof of Theorem 3.4 is complete.
Proof of Theorem 3.5. The proof of this theorem is identical to the proof of Theorem 3.4, except for the estimate of A 21 . This estimate is the only source of the 2 − 1 2 * power (instead of 2), and the only place where we used Assumption (A3), here replaced by (3.14). The estimate of A 21 using this L ∞ -bound assumption is actually rather simple. Recalling (A4) and using (3.14) on the equation (4.24) satisfied by p * D (u) − p * D ( u), we write
A 21 = Ω 1,T (P T u − u) Π D p * D (u) − Π D p * D ( u) dx P T u − u L ∞ (Ω 1,T ) Π D p * D (u) − Π D p * D ( u) L ∞ (Ω 1,T ) |Ω 1,T | h 2 u W 1,∞ (T1) Π D p * D (u) − Π D p * D ( u) L ∞ (Ω) h 2 u W 1,∞ (T1) δ Π D y D (u) − Π D y D ( u) .
(4.41)
The rest of the proof follows from this estimate.
Proof of the error estimates for the state and adjoint variables.
Proof of Proposition 3.2. Applying the triangle inequality twice,
Π D y D − y + ∇ D y D − ∇y ≤ Π D y D − Π D y D (u) + Π D y D (u) − y + ∇ D y D − ∇ D y D (u) + ∇ D y D (u) − ∇y .
The second and last terms on the right hand side of the above inequality are estimated using Theorem 2.3 as
Π D y D (u) − y + ∇ D y D (u) − ∇y WS D (y).
Subtracting (2.3a) and (4.2a), and using the stability property of GSs (Proposition 4.1), we obtain
Π D y D − Π D y D (u) + ∇ D y D − ∇ D y D (u) u − u h .
A combination of the above two results yields the error estimates (3.3) for the state variable. The error estimate for the adjoint variable can be obtained similarly.
Proof of Corollary 3.7. A use of triangle inequality leads to
y T − Π D y D ≤ y T − Π D y D (u) + Π D y D (u) − Π D y D ( u) + Π D y D ( u) − Π D y D . (4.42)
Consider the first term on the right hand side of (4.42). Using the Assumption (A1)-i), we obtain
y T − Π D y D (u) h 2 u + f H 1 (Ω) . (4.43)
Under the assumptions of Theorem 3.4, the second term on the right hand side of (4.42) is estimated by (4.31), and the third term is estimated by using (4.33) and (4.39). We plug these estimates alongside (4.43) into (4.42), and use (4.40) to conclude the proof of (3.16). The result for the adjoint variable can be derived similarly.
The full h 2 estimates are obtained, under the assumptions of Theorem 3.5, by following the same reasoning and using the improved estimate (4.41) on A 21 (which leads to improved estimates (4.31) and (4.39)).
5.
The case of Neumann BC, with distributed and boundary control 5.1. Model. Consider the distributed and boundary optimal control problem governed by elliptic equations with Neumann BC given by:
min (u,u b )∈U ad J(y, u, u b ) subject to (5.1a) −div(A∇y) + c 0 y = f + u in Ω, (5.1b) A∇y · n Ω = f b + u b on ∂Ω, (5.1c)
where Ω, A and f are as in Section 1.1, f b ∈ L 2 (∂Ω), c 0 > 0 is a positive constant, n Ω is the outer unit normal to Ω, y is the state variable, and u, u b are the control variables. The cost functional is
J(y, u, u b ) := 1 2 y − y d 2 + α 2 u 2 + β 2 u b 2 L 2 (∂Ω)
with α > 0 and β > 0 being fixed regularization parameters and y d ∈ L 2 (Ω) being the desired state variable. The set of admissible controls U ad ⊂ L 2 (Ω) × L 2 (∂Ω) is a non-empty, convex and closed set. For a general element V ∈ L 2 (Ω) × L 2 (∂Ω), v and v b denote its components in L 2 (Ω) and L 2 (∂Ω), that is,
V = (v, v b ).
It is well known that given U = (u, u b ) ∈ U ad , there exists a unique weak solution y(U ) ∈ H 1 (Ω) of (5.1b)-(5.1c). That is, y(U ) ∈ H 1 (Ω) such that, for all w ∈ H 1 (Ω),
a(y(U ), w) = Ω (f + u)wdx + ∂Ω (f b + u b )γ(w)ds(x), (5.2)
where a(z, w) = Ω (A∇z · ∇w + c 0 zw)dx and γ : H 1 (Ω) → L 2 (∂Ω) is the trace operator.
Here and throughout, · ∂ and (·, ·) ∂ denote the norm and scalar product in L 2 (∂Ω). We also denote · | · as the scalar product on L 2 (Ω) × L 2 (∂Ω) defined by
∀U, V ∈ L 2 (Ω) × L 2 (∂Ω) , U | V = α(u, v) + β(u b , v b ) ∂ .
The convex control problem (5.1) has a unique solution (y, U ) ∈ H 1 (Ω) × U ad and there exists a co-state p ∈ H 1 (Ω) such that the triplet (y, p, U ) ∈ H 1 (Ω) × H 1 (Ω) × U ad satisfies the Karush-Kuhn-Tucker (KKT) optimality conditions [30]:
a(y, w) = (f + u, w) + (f b + u b , γ(w)) ∂ ∀ w ∈ H 1 (Ω), (5.3a) a(w, p) = (y − y d , w) ∀ w ∈ H 1 (Ω), (5.3b) U + P α,β V − U ≥ 0 ∀ V ∈ U ad , (5.3c)
where P α,β = (α −1 p, β −1 γ(p)).
5.2.
The GDM for elliptic equations with Neumann BC.
Definition 5.1 (GD for Neumann BC with reaction). A gradient discretisation for Neumann BC is a quadruplet D = (X D , Π D , T D , ∇ D ) such that
• X D is a finite dimensional space of degrees of freedom, • Π D : X D → L 2 (Ω) is a linear mapping that reconstructs a function from the degrees of freedom, • T D : X D → L 2 (∂Ω) is a linear mapping that reconstructs a trace from the degrees of freedom, • ∇ D : X D → L 2 (Ω) n is a linear mapping that reconstructs a gradient from the degrees of freedom. • The following quantity is a norm on X D :
w D := ∇ D w + Π D w . (5.4)
If F ∈ L 2 (Ω) and G ∈ L 2 (∂Ω), a GS for a linear elliptic problem
−div(A∇ψ) + c 0 ψ = F in Ω, A∇ψ · n Ω = G on ∂Ω (5.5)
is then obtained from a GD D by writing:
Find ψ D ∈ X D such that, for all w D ∈ X D ,
a D (ψ D , w D ) = Ω F Π D w D dx + ∂Ω GT D w D ds(x), (5.6) where a D (ψ D , w D ) = Ω (A∇ D ψ D · ∇ D w D + c 0 Π D ψ D Π D w D )dx.
For Neumann boundary value problems, the quantities C D , S D and W D measuring the accuracy of the GS are defined as follows.
C D := max w∈X D \{0} T D w ∂ w D , Π D w w D . (5.7) ∀ϕ ∈ H 1 (Ω) , S D (ϕ) = min w∈X D Π D w − ϕ + T D w − γ(ϕ) ∂ + ∇ D w − ∇ϕ . (5.8) ∀ϕ ∈ H div,∂ (Ω) , W D (ϕ) = max w∈X D \{0} 1 w D Ω Π D wdiv(ϕ) + ∇ D w · ϕdx − ∂Ω T D wγ n (ϕ)ds(x) ,(5.9)
where γ n is the normal trace on ∂Ω, and H div,∂ (Ω) = {ϕ ∈ L 2 (Ω) n : div(ϕ) ∈ L 2 (Ω) , γ n (ϕ) ∈ L 2 (∂Ω)}. Using these quantities, we define WS D as in (2.11) and we have the following error estimate.
Theorem 5.2 (Error estimate for the PDE with Neumann BC). Let D be a GD in the sense of Definition 5.1, let ψ be the solution in H 1 (Ω) to (5.5), and let ψ D be the solution to (5.6). Then
Π D ψ D − ψ + ∇ D ψ D − ∇ψ + T D ψ D − γ(ψ) ∂ WS D (ψ).
Proof. The estimate
Π D ψ D − ψ + ∇ D ψ D − ∇ψ WS D (ψ) (5.10)
is standard, and can be established as for homogeneous Dirichlet BC (see, e.g., [16,Theorem 3.11] for the pure Neumann problem). The estimate on the traces is less standard, and hence we detail it now. Introduce an interpolant
P D ψ ∈ argmin w∈X D Π D w − ψ + T D w − γ(ψ) ∂ + ∇ D w − ∇ψ and notice that Π D P D ψ − ψ + T D P D ψ − γ(ψ) ∂ + ∇ D P D ψ − ∇ψ ≤ S D (ψ). (5.11)
By definition of C D and of the norm · D , for all v ∈ X D ,
T D v ∂ ≤ C D ( Π D v + ∇ D v ) .
Substituting v = ψ D − P D ψ, a triangle inequality and (5.11) therefore lead to
T D ψ D − γ(ψ) ∂ ≤ T D (ψ D − P D ψ) ∂ + T D P D ψ − γ(ψ) ∂ ≤ C D ( Π D ψ D − Π D P D ψ + ∇ D ψ D − ∇ D P D ψ ) + S D (ψ). (5.12)
We then use the triangle inequality again and the estimates (5.10) and (5.11) to write
Π D ψ D −Π D P D ψ + ∇ D ψ D − ∇ D P D ψ ≤ Π D ψ D − ψ + ψ − Π D P D ψ + ∇ D ψ D − ∇ψ + ∇ψ − ∇ D P D ψ WS D (ψ).
The proof is complete by plugging this result in (5.12).
5.3.
The gradient discretisation method for the Neumann control problem. Let D be a GD as in Definition 5.1, U h be a finite dimensional space of L 2 (Ω), and set U ad,
h = U ad ∩ U h . A GS for (5.3) consists in seeking (y D , p D , U h ) ∈ X D × X D × U ad,h , with U h = (u h , u b,h ), such that a D (y D , w D ) = (f + u h , Π D w D ) + (f b + u b,h , T D w D ) ∂ ∀ w D ∈ X D , (5.13a) a D (w D , p D ) = (Π D y D − y d , Π D w D ) ∀ w D ∈ X D , (5.13b) U h + P D,α,β V h − U h ≥ 0 ∀ V h ∈ U ad,h , (5.13c) where P D,α,β = (α −1 Π D p D , β −1 T DpD ).
Let Pr h : L 2 (Ω) × L 2 (∂Ω) → U h be the L 2 orthogonal projection on U h for the scalar product · | · . We denote the norm on L 2 (Ω) × L 2 (∂Ω) associated to · | · by |||·|||, so that |||V ||| We assume that Pr h (U ad ) ⊂ U ad,h . (5.14)
= α v 2 + β v b 2 . If W ∈ L 2 (Ω) × L 2 (∂Ω), we define E h (W ) = |||W − Pr h W |||.
Then there exists C only depending on Ω, A, α, β and an upper bound of C D such that
U − U h ≤ C E h (P α,β ) + E h (U ) + WS D (p) + WS D (y) .
Proof. The proof is identical to the proof of Theorem 3.1 (taking u d = 0), with obvious substitutions (e.g. P D,α ; P D,α,β and u h ; U h ) and the L 2 inner products (·, ·) replaced by · | · whenever they involve P D,α or u h . where Ω and A are as in Section 1.1. The cost functional is (1.2) with u d = 0 and y d ∈ L 2 (Ω) is such that Ω y d (x)dx = 0. Fixing a < 0 < b, the admissible set of controls is chosen as
U ad = u ∈ L 2 (Ω) : a ≤ u ≤ b a.e. and Ω u(x)dx = 0 .
For a given u ∈ U ad , there exists a unique weak solution y(u) ∈ H 1 (Ω) := {w ∈ H 1 (Ω) : Ω w(x)dx = 0} of (5.15b)-(5.15c).
The convex control problem (5.15) has a unique solution (y, u) ∈ H 1 (Ω) × U ad and there exists a co-state p ∈ H 1 (Ω) such that the triplet (y, p, u) ∈ H 1 (Ω) × H 1 (Ω) × U ad satisfies the Karush-Kuhn-Tucker (KKT) optimality conditions [30]:
a(y, w) = (u, w) ∀ w ∈ H 1 (Ω), (5.16a) a(w, p) = (y − y d , w) ∀ w ∈ H 1 (Ω), (5.16b) (p + αu, v − u) ≥ 0 ∀ v ∈ U ad , (5.16c)
where a(z, w) = Ω A∇z · ∇wdx.
Then, u can be characterized in terms of the projection formula given by
u = P [a,b] (−α −1 p + c),
where c is a constant chosen such that Ω u(x)dx = 0. The existence and uniqueness of this c follows by noticing that Γ(c) :
= Ω P [a,b] (−α −1 p + c) is continuous, lim c→−∞ Γ(c) = a|Ω| < 0, lim c→+∞ Γ(c) = b|Ω| > 0, and Γ is strictly increasing around c if Γ(c) = 0.
The adaptation of the theoretical analysis and numerical algorithms for this problem is a topic of future research.
Numerical results
In this section, we present numerical results to support the theoretical estimates obtained in the previous sections. We use three specific schemes for the state and adjoint variables: conforming finite element method, non-conforming finite element method, and hybrid mimetic mixed (HMM) method (a family that contains, the hMFD schemes analysed for example in [7], owing to the results in [17]). We refer to [19] for the description of the GDs corresponding to these methods (see also Section 7.1, Appendix for the HMM GD). The control variable is discretised using piecewise constant functions. The discrete solution is computed by using the primal-dual active set algorithm, see [36,Section 2.12.4]. Let the relative errors be denoted by Here, the definitions of u and u h follow from (3.11) and the discussion in Section 3.2.1:
• For FE methods,
u = P [a,b] (P T u d − α −1 p) and u h = P [a,b] (P T u d − α −1 Π D p D ).
• For HMM methods,
u |K = P [a,b] (P T u d − α −1 p(x K )
) for all K ∈ T , and
u h = P [a,b] (P T u d − α −1 Π D p D ) = u h .
The L 2 errors of state and adjoint variables corresponding to the FE methods are computed using a seven point Gaussian quadrature formula, and the energy norms are calculated using midpoint rule. In the case of HMM, both the energy and L 2 norms are computed using the midpoint rule. The L 2 errors of control variable is computed using a three point Gaussian quadrature formula. The post-processed control corresponding to the FE methods is evaluated using a seven point Gaussian quadrature formula, whereas for the HMM methods, the post-processed control is computed using midpoint rule. For HMM methods, we can use simpler quadrature rules owing to the fact that the reconstructed functions are piecewise constants. These errors are plotted against the mesh parameter h in the log-log scale.
6.1. Dirichlet BC. The model problem is constructed in such a way that the exact solution is known.
6.1.1. Example 1. This example is taken from [1]. In this experiment, the computational domain Ω is taken to be the unit square (0, 1) 2 . The data in the optimal distributed control problem (1.1a)-(1.1c) are chosen as follows: y = sin(πx) sin(πy), p = sin(πx) sin(πy),
u d = 1 − sin(πx/2) − sin(πy/2), α = 1, U ad = [0, ∞), u = max(u d − p, 0).
The source term f and the desired state y d are the computed using f = −∆y − u, y d = y + ∆p. Figure 1 shows the initial triangulation of a square domain and its uniform refinement.
Figure 1. Initial triangulation and its uniform refinement
Since Ω is convex, Theorems 3.1 and 3.4 (see also the discussion before Section 3.2.1), Proposition 3.2 and Corollary 3.7 predict linear order of convergence for the state and adjoint variable in the energy norm, nearly quadratic order of convergence for state and adjoint variables in L 2 norm, linear order of convergence for the control variable in L 2 norm, and a nearly quadratic order of convergence for the post-processed control. These nearly-quadratic convergence properties only occur in case of a super-convergence result for the state equation (i.e. Estimate (3.7)), which is always true for the FE methods but depends on some choice of points for the HMM scheme (see [21], and below).
Conforming FE method:
The discrete solution is computed on several uniform grids with mesh sizes h = 1 2 i , i = 2, . . . , 6. The error estimates and the convergence rates of the control, the state and the adjoint variables are calculated. The postprocessed control is also computed. Figure 2 displays the convergence history of the error on uniform meshes. As noticed in Remark 3.9 and as already seen in [34], we obtain linear order of convergence for the control and quadratic convergence for the post-processed control. The theoretical rates of convergence are confirmed by these numerical outputs. Non-Conforming FE method: For comparison, we compute the solutions of the ncP 1 finite element method on the same grids. The errors of the numerical approximations to state, adjoint and control variables on uniform meshes are evaluated. The convergence behaviour of state, adjoint and control variables is illustrated in Figure 3. Here also, these outputs confirm the theoretical rates of convergence.
HMM scheme: In this section, the schemes were first tested on a series of regular triangle meshes from [27] (see Figure 4, left) where the points P (see [19,Definition 2.21]) are located at the center of gravity of the cells (Test1). For such meshes, the state and adjoint equations enjoy a super-convergence property in L 2 norm [8,21] and thus, as expected, so does the scheme for the entire control problem after projection of the exact control. In Figure 5, the graph of the relative errors corresponding to control, state and adjoint variables against the discretisation parameter is plotted in the loglog scale. Test 2 focuses on a cartesian grid where the points P are shifted away from the centre of gravity (see Figure 4, right). For such a sequence of meshes, it has been observed in [21] that the HMM method can display a loss of superconvergence for the state equation. It is therefore expected that the same loss occurs, for all variables, for the control problem. This can be clearly seen in Figure 6 Figure 7 shows the initial triangulation of a L-shape domain and its uniform refinement.
Figure 7. Initial triangulation and its uniform refinement
Conforming FE method: The errors in the energy norm and the L 2 norm together with their orders of convergence are evaluated. These numerical order of convergence clearly match the expected order of convergence, given the regularity property of the exact solutions. The convergence rates are plotted in the log-log scale in Figure 8. Non-Conforming FE method: The errors between the true and computed solutions are computed for different mesh sizes. In Figure 9, we plot the L 2 -norm and H 1 norm of the error against the mesh parameter h.
HMM method:
The errors corresponding to control, adjoint and state variables are computed using HMM (Test 1). In Figure 10, the graph of the errors are plotted against the mesh size h in the log-log scale. Since Ω is non-convex, we obtain only suboptimal orders of convergence for the state and adjoint variables in the energy norms and L 2 norms. Also we observe suboptimal order of convergence for the post processed control. However, the control converges at the optimal rate of h.
6.2. Neumann BC. In this example, we consider the optimal control problem defined by (5.1) with Ω = (0, 1) 2 and c 0 = 1. We choose the exact state variable y and the adjoint variable p as y = −1 π (cos(πx) + cos(πy)), p = −1 π (cos(πx) + cos(πy)), We therefore have u d = 0. The source term f and the observation y d can be computed using f = −∆y + y − u, y d = y + ∆p − p. Conforming FE method: The errors and the orders of convergence for the control, state and adjoint variables are calculated for different mesh parameter h. The numerical errors are plotted against the discretisation parameter in the log-log scale in Figure 11. Figure 11. Neumann BC, test case corresponding to (6.1), conforming FE method Non-Conforming FE method: The error estimates and the convergence rates of the control, the state and the adjoint variables are evaluated. The post-processed control is also computed. Figure 12 displays the convergence history of the error on uniform meshes.
The observed orders of convergences agree with the predicted ones as seen in the figures.
7. Appendix 7.1. L ∞ estimates for the HMM method. Let us first briefly recall the GD corresponding to the HMM method [16,18]. We consider a polytopal mesh T = (T , E, P) as defined in [16,Definition 7.2]: T is the set of cells (generic notation K), E is the set of faces (generic notation σ) and P is a set made of one point per cell Figure 12. Neumann BC, test case corresponding to (6.1), nonconforming FE method (notation x K -this point does not need to be the center of mass of K in general). If K ∈ T then E K is the set of faces of K. For σ ∈ E K , |σ| is the measure of σ, x σ is the center of mass of σ, d K,σ = (x σ − x K ) · n K,σ is the orthogonal distance between x K and σ, n K,σ is the outer normal to K on σ, and D K,σ is the convex hull of x K and σ. An HMM GD is defined the following way.
• The degrees of freedom are made of one value in each cell and one value on each edge, so X D,0 = {v = ((v K ) K∈T , (v σ ) σ∈E K ) : v K ∈ R , v σ ∈ R , v σ = 0 if σ ⊂ ∂Ω}. • The reconstructed functions are piecewise constant in the cells: for v ∈ X D,0 , Π D v ∈ L 2 (Ω) is defined by (Π D v) |K = v K for all K ∈ T . • The reconstructed gradient is piecewise constant in the sets (D K,σ ) K∈T , σ∈E K :
if v ∈ X D,0 , then ∇ D v ∈ L 2 (Ω) n is defined by ∀K ∈ T , ∀σ ∈ E K ,
(∇ D v) |D K,σ = ∇ K v + √ n d K,σ (v σ − v K − ∇ K v · (x σ − x K ))n K,σ , where ∇ K v = 1 |K| σ∈E K |σ|v σ n K,σ
(this gradient is perhaps the most natural choice; though not the only possible choice within the HMM family; see [16,18] for a more complete presentation).
Under standard local regularity assumptions on the mesh, [16, Proposition 12.14 and 12.15] yield the following error estimate on WS D : if A is Lipschitz-continuous and ψ ∈ H 2 (Ω), for some C not depending on ψ or T:
WS D (ψ) ≤ Ch ψ H 2 (Ω) .
Under the quasi-uniformity assumption on the mesh, we establish the following L ∞ error estimate and bound for the HMM.
Theorem 7.1 (L ∞ estimates for HMM). Consider the dimension n = 2 or 3.
Let T be a polytopal mesh and D be an HMM gradient discretisation. Take ≥ θ T + ζ D + χ T , where θ T and ζ D are defined by [16,Eqs. (7.8) and (12.18)], and
χ T = max K∈T h n |K| .
Assume that A is Lipschitz-continuous, that Ω is convex and that F ∈ L 2 (Ω). There exists then C, depending only on Ω, A and , such that, if ψ solves (2.1) and ψ D solves (2.2),
Π D ψ D − ψ T L ∞ (Ω) ≤ C F h| ln(h)| if n = 2, h 1/2 if n = 3, (7.2)
where (ψ T ) |K = ψ(x K ) for all K ∈ T , and
Π D ψ D L ∞ (Ω) ≤ C F . (7.3)
Proof. In this proof, X Y means that X ≤ M Y for some M depending only on Ω, A and . The theorem's assumptions ensure that ψ ∈ H 2 (Ω) ∩ H 1 0 (Ω) ⊂ C(Ω). Let v = ((ψ(x K )) K∈T , (ψ(x σ )) σ∈E ) ∈ X D,0 . By the proof of [16,Proposition A.6] (see also [16, (A.10)]),
Π D v − ψ + ∇ D v − ∇ψ h ψ H 2 (Ω) h F .
A use of (7.1) and the triangle inequality then gives ∀w ∈ X D,0 , Π D w L q (Ω) q ∇ D w . (7.5) An inspection of the constants appearing in the proof of [16,Lemma B.12] shows that the inequality in (7.5) is independent of q. Substitute w = v − ψ D in (7.5) and use (7.4) to obtain
∇ D (v − ψ D ) h F .Π D (v − ψ D ) L q (Ω) hq F . Let K 0 ∈ T be such that Π D (v − ψ D ) L ∞ (Ω) = |Π D (v − ψ D ) |K0 | and write Π D (v − ψ D ) L ∞ (Ω) = |K 0 | −1/q |K 0 | |Π D (v − ψ D ) |K0 | q 1/q ≤ χ 1/q T h − n q Π D (v − ψ D ) L q (Ω) h 1− n q q F .
Minimising q → h 1− n q q over q ∈ [1, ∞) if n = 2, or taking q = 6 if n = 3, yields
Π D (v − ψ D ) L ∞ (Ω) F h| ln(h)| if n = 2, h 1/2 if n = 3.
This concludes (7.2) since Π D v = ψ T . Estimate (7.3) follows from (7.2) by using the triangle inequality, the estimate ψ T L ∞ (Ω) ≤ ψ L ∞ (Ω) F and the property max(h 1/2 , h| ln(h)|) 1.
Proposition 3. 2 (
2State and adjoint error estimates). Let D be a GD, (y, p, u) be the solution to (1.4) and (y D , p D , u h ) be the solution to (2.3). Then the following error estimates hold:
Remark 3. 3 (
3Rates of convergence for the control problem). Owing to Remark 2.4, under sufficient smoothness assumption on u d , if A is Lipschitz continuous and (y, p, u) ∈ H 2 (Ω) 2 × H 1 (Ω) then (3.2), (3.3) and (3.4) give linear rates of convergence for all classical first-order methods.
Theorem 3. 5 (
5Super-convergence for post-processed controls II). Let the assumptions and notations of Theorem 3.4 hold, except (A3) which is replaced by:
Corollary 3. 7 (
7Super-convergence for the state and adjoint variables). Let (y, p) and (y D , p D ) be the solutions to (1.4a)-(1.4b) and (2.3a)-(2.3b). Under the assumptions of Theorem 3.4, the following error estimates hold, with C depending only on α:
3. 2 . 1 .
21Discussion on (A1)-(A4) and post-processings. To discuss (A1), (A2) and the post-processing choices (3.11), let us consider two situations depending on the nature of Π D . This nature drives the choices of w T , to ensure that the superconvergence result (3.7) holds.
• hMFD schemes: η is an upper bound of θ T defined by[19, Eq. (2.27)] and, for all K ∈ T ,
2. 1 ,
1Properties (3.8) and (3.9) follow from (4.20); (A2) is trivially true, and (A3) follows from the discrete functional analysis results of [16, Lemma 8.15 and Lemma 13.11].
Proposition 4. 1 (
1Stability of gradient schemes). Let a be a coercivity constant of A. If ψ D is the solution to the gradient scheme (2.2), then
( 4 . 36 )
436Subtracting the equations (2.3a) and (4.2a) (with u instead of u) satisfied by y D and y D ( u), choosing w D = p * D ( u) − p D , and using the equations (2.3b) and (4.18) on p D and p * D ( u), we find
of (4.35), (4.36) (together with the estimates (4.23) and (4.32) on A 1 and A 2 ), (4.37) and (4.38) into (4.34) yields an estimate on u h − u which, when plugged into (4.33), gives
Theorem 5. 3 (
3Control estimate). Let D be a GD in the sense of Definition 5.1, U be the optimal control for (5.3) and U h be the optimal control for the GS (5.13).
Remark 5. 4 (
4Super-convergence of the control for Neumann problems). Using the same technique as in the proof of Theorem 3.4, and extending the assumptions (A1)-(A4) to boundary terms in a natural way (based on trace inequalities and Sobolev embedding of H 1/2 (∂Ω)), an O(h 3/2 ) super-convergence result can be proved on post-processed controls for Neumann BC.
Remark 5. 5 .
5Consider the distributed optimal control problem governed by elliptic equations with Neumann BC given by:min u∈U ad J(y, u) subject to (5.15a) −div(A∇y) = u in Ω, (5.15b) A∇y · n Ω = 0 on ∂Ω, Ω y(x)dx = 0, (5.15c)
err D (y) := Π D y D − y τ y τ , err D (∇y) := ∇ D y D − ∇y ∇y err D (p) := Π D p D − p τ p τ , err D (∇p) := ∇ D p D − ∇p ∇p err(u) := u h − u u and err( u) := u h − u u .
Figure 2 .
2Dirichlet BC, example 1, conforming FE method
Figure 3 .
3Dirichlet BC, example 1, non-conforming FE method
Figure 4 .
4Mesh patterns for the tests using the HMM method (left: Test 1; right: Test 2).
. 6.1.2. Example 2. In this example, we report the results of numerical tests carried out for the L-shaped domain Ω = (−1, 1) 2 \ ([0, 1) × (−1, 0]). The exact solutions
Figure 5 .Figure 6 .
56Dirichlet BC, example 1, HMM (Test1) Dirichlet BC, example 1, HMM (Test2) are chosen as follows, and correspond to u d = 0. y(r, θ) = r 2 cos 2 θ − 1 r 2 sin 2 θ − 1 r 2/3 g (θ) , U ad = [−600, −50], α = 10 −3 , u = P [−600,−50] − 1 α p where g (θ) = (1 − cos θ) (1 + sin θ) and (r, θ) are the polar coordinates. The source term f and the desired state y d can be determined using the above functions. The interest of this test-case is the loss of H 2 -regularity property for the state and adjoint equations.
Figure 8 .
8Dirichlet BC, example 2 (L-shaped domain), conforming FE method
Figure 9 .
9Dirichlet BC, example 2 (L-shaped domain), nonconforming FE method
Figure 10 .
10Dirichlet BC, example 2 (L-shaped domain), HMM
U
ad = [−750, −50], α = 10 −3 , u(x) = P [−750,−50] − 1 α p(x) .
,
Lemma B.12] establishes the following discrete Sobolev embedding, for all q ∈ [1, 6] if n = 3 and all q ∈ [1, +∞) if n = 2:
Table 1. List of abbreviations 1.1. The optimal control problem for homogeneous Dirichlet BC.Abbreviations Meaning
FE
Finite Element
GDM
Gradient Discretisation Method, see Section 2
GD
Gradient Discretisation, see Definition 2.1
GS
Gradient Scheme, see (2.2) for PDEs
MFD
Mimetic Finite Difference method, a family of numerical schemes
for diffusion equations on generic meshes. hMFD is the hybrid
Mimetic Finite Difference method, a member of this family based
on unknowns located in the cell and on the faces.
HMM
Hybrid Mimetic Mixed method, a family of numerical methods for
diffusion equations on generic meshes, that contains hMFD as a
particular case. See Section 7.1 for a presentation of the gradient
discretisation corresponding to the HMM scheme.
Con-
sider the distributed optimal control problem governed by the diffusion equation
defined by
min
u∈U ad
J(y, u) subject to
(1.1a)
−div(A∇y) = f + u in Ω,
(1.1b)
y = 0 on ∂Ω,
(1.1c)
Acknowledgement: The first author acknowledges the funding support from the Australian Government through the Australian Research Council's Discovery Projects funding scheme (project number DP170100605). The second and third authors acknowledge the funding support from the DST project SR/S4/MS/808/12.
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Australia. jerome.droniou@monash. India. [email protected] IITB. 3800School of Mathematical Sciences, Monash University ; Department of Mathematics, Indian Institute of Technology BombayIndia. [email protected] of Mathematical Sciences, Monash University, Clayton, Victoria 3800, Aus- tralia. [email protected] Department of Mathematics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. [email protected] IITB-Monash Research Academy, Indian Institute of Technology Bombay, Powai, Mum- bai 400076, India. [email protected]
| This paper considers the spectral element approximation of the Stokes problem and the conditioning of the resulting discrete problem. The well-posedness of the variational formulation of the Stokes problem and, in particular, the uniqueness of the pressure has been demonstrated when the subspace of square-integrable functions having vanishing mean is chosen for the pressure space. In the discrete setting a conforming subspace is chosen for the discrete pressure space and the analysis of the discrete problem is based on this choice. However, this space is not used in practical implementations of finite or spectral element methods for the Stokes problem. In this paper it is shown how the zero volume condition on the pressure may be accommodated within the trial space by modifying the continuity equation in a consistent manner. The dependence of the condition number of the Uzawa operator and the accuracy of the spectral element approximation on the weighting factor is investigated. | 1,999,717 | We develop a general variational framework for the finite element solution of the pure Neumann problem. Our starting point is the equivalence between the weak Neumann equation and a minimization problem on the factor space H 1 ()/R I . This problem gives rise to a family of minimization problems posed on conventional Sobolev spaces but constrained by a generalized zero-mean condition. We show that the constraint’s choice and implementation is the paradigm that describes finite element methods for the Neumann problem. In terms of finite element algebraic problems it specializes to a discrete projection choice and reveals connections with methods for equality constrained quadratic programs. We use this paradigm to develop a novel class of regularized finite elements. Numerical experiments indicate that this class consistently outperforms other finite elements for the Neumann problem. | A Primal-Dual Weak Galerkin Finite Element Method for Second Order Elliptic Equations in Non-Divergence Form | Nearly H1-optimal finite element methods | What is the Finite Element Method? | In the paper a balanced Neumann Neumann algorithm for the reduced HCT finite element nonmatching meshes is discussed. The overall discretization is done using a mortar technique which is based on the application of an approximate matching condition for the discrete functions. The algorithms are analyzed using the abstract Schwarz framework, proving an almost optimal condition bound which is independent of the parameters of the problem, and depends only logarithmically on the ratio between the subdomain size and the mesh size. | We consider a space-time finite element method on fully unstructured simplicial meshes for optimal sparse control of semilinear parabolic equations. The objective is a combination of a standard quadratic tracking-type functional including a Tikhonov regularization term and of the $L^1$-norm of the control that accounts for its spatio-temporal sparsity. We use a space-time Petrov-Galerkin finite element discretization for the first-order necessary optimality system of the associated discrete optimal sparse control problem. The discretization is based on a variational formulation that employs piecewise linear finite elements simultaneously in space and time. Finally, the discrete nonlinear optimality system that consists of coupled forward-backward state and adjoint state equations is solved by a semismooth Newton method. | On convergence of numerical methods for variational–hemivariational inequalities under minimal solution regularity | On convergence of numerical methods for variational–hemivariational inequalities under minimal solution regularity | Smoothed finite element method for topology optimization involving incompressible materials |
1,999,718 | Make corner covers for the grill. | We have a full grill and not a built in grill but this cover is just the right amount of cover without all the bulk of a full cover. We have a lot of wind and it fits tight enough to stay put (some elastic on the bottom). I had to move the tie-downs to connect to the front door handles but because I sew, that was not a problem. | Grill guy here, so I noticed how bricking takes away so much time for me since Im very much looking to see every corner clean, but then again its part of the reason I always come out late. Hopefully theres an easier way of doing this. | Grilling restaurant floor plan? | I'm new to the world of grilling, and am firing it up for the first time tomorrow night at my birthday party. Anyone have some great recipes, tips, or advice for a novice griller?
I eat pretty much all meat, vegetables (especially a fan of corn off the grill), and probably pretty much anything else that can be grilled.
Thanks! | Bought this to cover our small (18.5" diameter) electric outdoor George Foreman grill, which we keep outside on our deck. Our grill has a domed cover, like a Webber kettle grill. Most covers we saw in the stores were too big, designed for 25" or more diameter grills. This cover fits perfectly, is a nice heavy cover, looks nice, and has a cord at bottom to tighten to keep wind out. Very happy with purchase and would recommend to anyone looking for a small grill cover. | I have a 12" Kicker in my trunk and I want to protect it with a grill. Does anyone use Grills, If so post link. Thanks | This is the best indoor bbq ever. Bought one over 25 years ago and used it amost every other week in winter time for wonderful grilled steak, lamb rack, and fish. I don't have the rotissoire but don't need one. I have founded that a piece of aluminium foil bend into the shape of a boat and put over the meat will enhance very much the grilling; maybe it retain hot air or reflect the infrared energy that make grilling way faster and without the cover foil. It more adds more flavor than grilling by contact with a hot metallic surface. I put the grill on the electric stove right under the hood to eliminate all odor or smoke that could be produce by the grill. I also use aluminium foil to cover all surface of the grill including the drip pan. After, you just throw the foils into the garbage thus saving cleaning time a lot. For the same purpose, i also coated the horizontal metallic grill with cooking oil to ease the cleaning afterward. | I would not recommending getting these. When it gets hot it will melt and they pop out easy. Spend the money and get a better grill. | 1,999,718 | I had to make corner covers so that the corners of my grill would not tear through. | Covers the grill nicely. I bought it to replace my original cover ... | I didn't think it was possible to be impressed by a grill cover | ... had this grill cover for a week so it's pretty early to comment on it | Good cover for your grill | Grill cover fits well, but fades easily | ... grill to keep them in place they were exactly like the originals | This grill cover is a perfect fix for my grill | Char-Griller 3055 Custom Grill Cover |
1,999,719 | what percentage of the uk's pizza sales are delivered via the internet | Just wanted to let you fine ladies and gentlemen know that, at least for pizzas (regardless of size or type, as best I can tell) Domino's is doing 50% off menu price for online orders. Some restrictions may apply, see online offer for details. | I'm a designer tasked with redesigning the Dominos website(UK), how you order Pizza and how to wade through the deals to get the best offer.
Just wondering if anyone had any thoughts out there on how they think the best way to order a pizza would be! Is it speed, cheapest deals, best quality? | EDIT: I ended up just getting it to them via Google Pay. Thanks everyone for the suggestions! It's funny the unexpected differences you encounter sometimes.
Hey, I'm an American and I bought someone an e-gift card for Domino's Pizza (delivered via email) and was told he couldn't use it in England. How can I buy a gift card for him online for Domino's? If it's not possible, can anyone give me examples of common pizza places in England that an American can definitely, definitely buy gift cards delivered via email that are usable for someone in England? | When the Gulls score more than 3 goals, Papa Johns honors 50% off on online orders the next day...
So if you want pizza, use the code GULLS3 and get half off! | was the first to introduce drone-delivery pizza in November 2016, partnering with Flirtey Drone Delivery. Australia Currently, there are around 600 Domino's stores in Australia, with the company planning to expand the number of stores by 3 each week over a 3 month period. The Australian stores are spread right across the country, from the main capital cities like Melbourne, Adelaide and Sydney, to more rural areas like Armidale. Domino's Pizza Enterprises Domino's Pizza Enterprises Limited (DPE) is the largest pizza chain in Australia in terms of network store numbers and network sales, as well as the largest franchisee for | Currently setting up my store, my product ships to the uk through oberlo in around 10 days but upto 30 for the US so i am planning on only shipping only to the uk will this make it harder to get sales? i thought that if i just put all my fb ad money into the uk only then that should balance it out but im not sure any advice? | This runs out October 30th, but at the mo you can get any pizza for £5 (if you go in a pick it up) - don't know if you can order, then collect, or if you must go in. But I did last week, got 3 for £15 plus free garlic bread portion. Don't know how they compare to others as I'm not a big pizza eater but they were alright (hows THAT for a glowing recommendation) and for £5 can you really go wrong ? | Dominos 50% off any pizza ends today. Only good if you order online! | 1,999,719 | Domino's Pizza Group placed through the widget. Domino's iPhone ordering app was introduced in January 2011, and took £1 million in its first three months. In June 2011, the company launched Android and iPad apps. A Windows Phone 7 app followed in 2012. The company also makes use of discount codes. Domino's growth in e-commerce continues with 61.5% of all United Kingdom delivered sales (2012: 56.1% of United Kingdom delivered sales) coming via the internet. Sales taken through all online platforms were up in 2013, by 28.2% to £338.0m (2012: £263.7m) and, of this, 30.9% was taken through a mobile device (2012: 19.7%). | how many customers do sterlings mobile have | how many customers does sterlings mobile have today | when did windows phone marketplace change to windows store | when did lenovo start selling phones in the uk | who reported the market share of windows phone in 2013 | in what year did microsoft buy nokia for 5.4 billion euros | I know I missed the weekly "Is there an app for that" thread, but I'm curious if there is a price comparison app for groceries on Windows Phone. | who was the ceo of nokia when microsoft launched its mobile product |
1,999,720 | What laptop should I buy as a future Civil Engr. major in college? | Hey all, I'm heading into my first year in a bachelor of science and am currently looking for a laptop. I'm not entirely sure what I want to major in as of yet, but the areas I'm looking at are physics, computer science or engineering. I have a good desktop at home, and I hear there are computers I can use on campus. Will I need a laptop that's a bit stronger, or can I get away with something more basic just for word processing/watching lectures on my commute? | Hello! I am a CS student, like most CS students I don't have a fast laptop. But the thing is I have a laptop with 2 gigs of ram and a 512 GB hard drive. I cannot upgrade my laptop till next year (due to some problems) so instead of whining I have made, kind of a challenge for myself that I will learn all the technologies that I have to learn on this laptop, also I don't have any other option. The technologies that I have planned to learn before 2021 are:
C++
Java
Javascript
I don't plan to master all these in just a year, I don't think you can even master all these technologies in such a short span of time but I want to be proficient enough that I can at least claim to "know" these technologies, and maybe add it to my resume. That apart the main question is, What tools do you think will make my learning experience smooth? Keeping in mind my laptop's configurations.
I am asking for IDEs which would work flawlessly or maybe any lightweight text editor. Also I am open to all options doesn't mater if has a huge learning curve, but it shouldn't slow my laptop. Also some instructions on how to make most of what I have would be a great contribution. | So I am going into college in the next few months and I will be needing a laptop.
Thanks to black friday, the acer predator helios 300 is priced at 1050$ which is within budget. It offers the possibility to play all games at max settings. Downside would be short battery life and having to carry it around (its almost 3 kgs).
On the other hand, the Mi Notebook Pro is at 1120$ (doesnt have a black friday sale). It has ~8-9hrs of battery life and can handle some light gaming (which i intend to do, nothing too heavy).
I really am torn, whats the better option and why?
P.S: dont recommend to build a desktop. I am aware that it would be the best choice, however i need a laptop for uni. | I am currently a 3rd year Mechatronic Engineering student and I'm looking into buying a new laptop which I can use for my academic work as well (primarily programs such as Autodesk Inventor and MATLAB). The laptop I'm looking at is an ASUS FX504GD.
Firstly, could anyone perhaps confirm whether this would be a good option?
Secondly, would someone say that opting for 12GB RAM over 8GB RAM, which would cost me about $50 more, is worthwhile for what I need the laptop to do. | Hey Guys,
I will be joining University this September (HoPeFulLy.) I will be majoring in the Computer Science and Engineering Major. Which Thinkpad would you suggest me to get. I am setting a max price of around
USD 1400 ± USD 100
Thanks in Advance.
PS: I am in Indonesia so I will be flying to Canada for Uni. | I’ll be attending college in the fall and i’m curious what laptop or software is best for my major.
I know that MacOS excel is limited compared to Windows Excel.
I’ve always used Macs and their products so I’m not that familiar with PCs, but I can always figure things out.
Any insight? | I am heading towards the IT work and I have no idea which operating system is best for the field and what laptop should I get? Heard a lot of things about MacBooks, but still have no idea if it would be the most useful in a cyber security environment. | Hello all!
I have recently graduated from undergraduate studies and will be starting my Ph.D. candidacy this coming fall in Molecular Biology. My laptop has seen five years of constant use and needs to be replaced. I was wondering if anyone has any suggestions regarding what type of computer I should invest in. Suggestions on what operating system, what model, or what company are all welcome.
Would investing in a small laptop only for word processing and internet and a desktop for my apartment be useful?
Thanks!! | 1,999,720 | My dad wants to buy me a laptop for college by this fall when college starts which would be used for whatever programs Civil Engineers use + all my other classes in college which would just probably be research and typing for English class or something. Some say the Lenovo W500 could be good from what I've seen on the internet but I am open to any recommendations under $1000.
About 14"-16" inches, uses Windows, and under $1000.
It would be nice if it allowed some gaming :D but not a major or required thing.
Thanks in advance. | What kind of laptop should I buy? Should I bring my PC to college? | Laptop for College and Light Gaming | Decent laptop for college | Looking for laptop for college > $500 USD | Best Laptop for College and Gaming | Going to College and need a laptop $1k budget | LAPTOP for incoming freshman | Laptop for university (around $700-800 CAD) |
1,999,721 | I haven't gotten this product yet but i KNOW i will love it! I give it 5/5 stars | Gave it 4 stars because haven't had it long . But it has worked flawlessly so far so I am happy with this product . | Finally received it. It took so long I forgot all about it. The product is great! | excellent 5 star love it got an a plus from school thank you this was an excellent product thank you so much | 5 stars!! Product works great, reasonable price... And the customer follow up A-1 service and class. Best purchase, extremely happy with experience... | Was very surprised by this product! Seriiously love it! My girlfriend was surprised even more last night :) | Wow! Awesome product! Great quality and arrived quick! Love it! Can't wait to see what other products Exinoz offers! | This is a beautiful product I love it if I could give it more than five stars I would I would definitely buy from you again | I can't believe I didn't know about this till just recently. This is an amazing product! | 1,999,721 | I am giving this 1 star just because it is more noticeable, I haven't gotten this product yet but i KNOW i will love it! I give it 5/5 stars, but just wondering when is the limited edition ending? I would really like to know so I can order it in time for my friend's birthday coming up in November. | Hi! I just bought overwatch and I'm in love but when is ranked going to be live? | When will Limited and Ultimate packs come back again? | How long will the collectors edition of Tokyo (issue 9) be available? | when does the gift come out on itunes | When does the full game come out? | I bought this on Jan. 22, just 1 ... | Does the spring deadline of July 1 includes the date July 1 for application submission? | BeyondHD is currently open for 7 Days ending 7th March 2016 @ 8.00+12 GMT |
1,999,722 | Did I accidentally damage my Yamaha HS7‘s ? | I lent my beautiful Fender to my cousin for a while. I got it back, opened it up and found the following damage.
He tells me "it must've got knocked" whilst he was carrying it somewhere. I don't believe that much damage, whilst in its protective bag can happen. What do you guys think? Could this happen just by accident whilst being carried?
The imgur album contains a picture of the gig bag, the guitar inside the gig bag and the damage in question.
I'm really angry because I really don't believe that kinda damage happens with "just a knock" and it must've been some substantial force to cause it, either when the guitar was out of the bag or when inside. | So today I accidentally spilled a little bit of water and of course it lands perfectly in the top holes on my case and of course my pc turns off. The power button on my computer stopped working so I decided to use the ole screw driver trick to jump start the motherboard hoping it would post so I could see the damage(bad idea, really bad idea) it ended up sparking and I fried the entire motherboard :/ So now I have no idea what components I fried along with my motherboard and I’m basically fucked. Moral of the story do not do any of the things my dumbass did. | Not all it's the client's fault you know.
One day, I was handling a computer with a bizare Perfect Choise PSU I can't find anywhere online, this computer had been struck by lightning and so the PSU was fried, even with the surge protector.
So this computer had a space for cable management, and everything was held in place with zip ties, and so i had to cut them off.
So because I was in a hurry to get the job done, I used a heavy cutter, a durable one, slide the tip in, and cut them with a swing.
What could possibly go wrong?
I used too much force.
The next moment I stared in horror, I had not only cut the zip tie,but slashed the back of the motherboard.
No no no no no no...
But yes, after swapping the PSU, i tried to turn it on, and didn't respond, tried and tried, nothing, I had to confess to my boss for what I had done and face it.
I had to face the owner of the computer and put my own money to replace the motherboard and reinstall everything in the computer, at least the motherboard now has USB 3.0 and 4 RAM slots, so it was a win win for the store but not for me.
please kids, don't go lazy and do what I did.
TL;DR: This lizard was lazy and slashed a motherboard, paid for it.
I need some skooma, has anyone seen a Khajiit? | I got power bombed during a flying arm bar drill back in '03. I was dropped on the bottom of my neck really screwing up my future in the sport as well as my back. A few things have changed and I have the opportunity to start rolling again. I would really appreciate the input. | Arrived with no damage. I purchased these for the office. Nice for coffee and hot water in meeting room. Good price. I would purchase again if needed. | I did the unthinkable. I managed to knock my One R and it's left a nasty scrape on one of the lenses on the 360 mod. Only minutes early I somehow managed to lose the silicone lens cover and sod's law struck by damaging the lens soon after.
When viewing images this results in a black spot hovering in the image.
So, 3 questions:
- is it worth trying to repair this myself, or an I likely to do more damage?
- where can I get it repaired or replaced? I'm in the UK
- how much is a repair/replacement likely to cost me?
I don't have any kind of care plan or insurance to cover the damage | So yesterday I was being a total idiot and didn't lock the button on my mod and put it down next to a blanket, which ended up pressing the button in for about a minute before I noticed. Obviously the wick was burnt to all hell, and the mod was HOT to the point where I couldn't even touch it with my bare hands... I let everything cool down for about 30 minutes, then put the battery back in the charger and it read. There is no visible damage to anything: the mod, battery, and RDA show no signs of damage, but I'm wondering if it's still safe to use everything, or if I should just ditch it and get a new one?
Definitely learned my lesson. I'm glad nothing exploded or caught on fire. One of the dumbest things I've ever done. | In Korneuburg Power Station, EVN AG operates a combined cycle plant, consisting of a type GT13D gas turbine, a steam turbine and a heat recovery steam generator without auxiliary firing. This plant is mainly used for demand in the electric grid in the idle and in the peak load phases. On November 15, 2001 a fracture of a blade in the third turbine row happened during full load operation. This caused serious damage in the following blade rows, the blade carrier, and the turbine casing. This article reports on the accident and the damages in the gas turbine. A further section deals with both the possibility of a refurbishment and a replacement of the damaged gas turbine. | 1,999,722 | Hey there,
I recently bought a pair of Yamaha HS7‘s. My audio interface is the Behringer UMC202HD.
I know about the proper order in which you should power your monitors on and off. But what I didn’t know was that my MacBook the interface is connected with, stops giving power to USB devices when it goes into sleep mode.
So every time I went into the living room the speakers made this load pop noise without me noticing it. One time I sat in front of my speakers when it happened. First, there was a load “scratching” sound and then a loud pop sound.
I guess that happened around 12-15 times in a very short period of time.
I have now fixed this issue by connecting the audio interface to a powered USB hub.
But I’m very afraid of having damaged my monitors.
Can anyone please tell me if that’s possible?
I listened to a frequency test and I didn’t hear any distortion, but I’m not sure if I can really tell.
I think one of them is slightly louder and has more bass than the other, but that’s normal I guess..
Thanks in advance! | Random static sound coming through either monitor itself or speakers. | power on and pair with my macbook pro or my android it hearing a terrible noise and the hedaset poweroff | Monitor speakers keep re-enabling | Thinking about buying a One, but I think I have an issue with my Monitor/Speaker situation... | Help : Turning on/off the speakers makes my monitor goes blank - possible noob question | Speakers are distorted and not smooth sounding at all, pops, and distortion. USB hook-up didn't work. | Distortion on new desktop speakers. | AudioEngine 2 (A2) Premium Powered Desktop Speakers - Review |
1,999,723 | who invited hanna reitsch to the white house | Wendell Willkie advisors. Willkie visited the president at the White House for the first time as an ally on January 19, 1941, the evening before Roosevelt's third swearing-in. The president asked Willkie to be his informal personal representative to Britain, and Willkie accepted. Eleanor Roosevelt recorded that family members and White House staff found excuses to observe Willkie, and she would have done so herself had she been aware of the visit as it was happening. Roosevelt urged Willkie to see W. Averell Harriman and Harry Hopkins, both in London on missions from Roosevelt, and gave his former rival a letter to | wrote his 1974 State of the Union Address at the house and, after leaving office, was a guest at Sunnylands when President Gerald Ford pardoned him for any wrongdoing in the Watergate scandal. President Ford and his wife Betty were frequent guests as well. President Ronald Reagan and Nancy Reagan were close friends of the Annenbergs and visited every New Year's for 18 years. President Reagan also delivered one of his final radio addresses to the nation and signed the intent to pursue NAFTA from Sunnylands in January 1989. President George H. W. Bush hosted a state dinner at the | Richard C. Cook Richard C. Cook (born October 20, 1946) is a former U.S. federal government analyst, who was instrumental in exposing White House cover-ups regarding the Space Shuttle Challenger disaster of 1986. As a witness to the incident and a participant in the subsequent investigations, Cook provided key documents to "The New York Times" and testified before the Rogers Commission. In 1990, he received the Cavallo Foundation Award for Moral Courage in Business and Government for his testimony. In 2007, his memoirs of the tragedy were published in "Challenger Revealed: An Insider’s Account of How the Reagan Administration Caused | White House Passover Seder were often evoked during discussion at the meal. At the point in the ritual when the prophet Elijah is welcomed to the meal, the guests recited the Emancipation Proclamation. The choice of serving pieces was also symbolic. In 2009, the group used silverware from the Truman administration, remembering Truman as the first President to recognize Israel. In 2013, Israel First Lady Sara Netanyahu gave as a gift a Seder Plate, which was used each year at the dinner. Those in attendance read from the Maxwell House Haggadah, which is widely used in Jewish homes. The menu at the White House | Charles Rebozo Nixon. Rebozo first met then-U.S. Representative Nixon in 1950 through Florida Representative George Smathers. Smathers had recommended Key Biscayne as a vacation destination to Nixon, who eventually established a residence there which was later nicknamed the "Winter White House" by journalists. While Nixon was vacationing in Key Biscayne, Smathers had Rebozo take Nixon deep sea fishing. Rebozo and Nixon then started a friendship that endured 44 years. Rebozo quickly became best friend and financial and real estate advisor to Nixon. In 1968 Rebozo changed his party from Democratic to Republican. According to Rebozo, the two men were swimming together at | Backstairs at the White House staff. Mrs. Taft is pleased with how Maggie does her hair. Maggie first meets President Taft when she discovers her ten-year-old daughter Lillian Rogers (Tania Johnson) eating ice cream with him. When Nellie has a stroke, President Taft and Maggie help her learn to speak again. Lillian (Leslie Uggams), older now and crippled in one leg from polio, takes in work as a seamstress. Maggie keeps her busy and employed with small work orders from the White House. Wilson: In 1913 President Woodrow Wilson (Robert Vaughn) is elected and his family moves into the White House. First Lady Ellen Wilson | WASHINGTON (AP) — The Latest on the White House visit of French President Emmanuel Macron (all times local):
12:16 p.m.
A pair of designers is responsible for Melania Trump’s white skirt suit and matching hat.
The first lady’s office says Michael Kors designed the two-piece suit that Mrs. Trump wore for Tuesday’s White House arrival ceremony for President Emmanuel Macron of France and his wife, Brigitte.
Mrs. Trump also wore the suit on an outing to the National Gallery of Art in Washington with Mrs. Macron.
The first lady topped her outfit with a broad-brimmed white hat designed by Herve Pierre. Pierre designed the first lady’s inaugural ball gown.
The white hat quickly became the talk of the town, as well as on Twitter. Mrs. Trump typically doesn’t wear hats.
Still to come is Tuesday night’s piece de resistance: the first lady’s state dinner gown.
___
10:40 a.m.
President Donald Trump is warning that if Iran restarts its nuclear program it “will have bigger problems than they have ever had before.”
Trump and French President Emmanuel Macron will be discussing the Iran nuclear deal Tuesday during their meetings at the White House.
Macron wants Trump to maintain the deal. Trump is undecided but has called it “a terrible deal.”
Though Trump has warmly welcomed Macron to Washington, the two have disagreements to sort through, including Trump’s decision to leave the multinational Paris climate change agreement.
While with Macron, Trump refused to answer a reporter’s question as to whether he is considering a pardon for his personal lawyer, Michael Cohen, whose office was raided by the FBI. Trump called it “a stupid question.”
Cohen has not been charged.
___
9:54 a.m.
French President Emmanuel Macron is highlighting the close ties between his nation and the United States during his visit to the White House.
Macron, standing alongside President Donald Trump Tuesday, said “America represents endless possibilities for my country.”
He also told Trump that “France shares with your country an ideal of freedom and peace.”
Macron touted how the French fought alongside George Washington during the American Revolution, which laid the blueprint for cooperation between the nations.
The French president, who enjoys a closer relationship with Trump than many of his European peers, said that France works alongside the U.S. on challenges like terrorism, North Korea and Iran.
He is expected to lobby Trump to maintain the Iran nuclear deal and reconsider the decision to withdraw from the Paris climate agreement.
___
9:30 a.m.
President Donald Trump is sending prayers to the Bush family and wishing former President George H.W. Bush a “speedy recovery.”
Trump is recognizing the former president as he greets French President Emmanuel Macron on the South Lawn of the White House.
Bush has been hospitalized in Houston with an infection, just days after attending the funeral of his wife, Barbara Bush.
Trump is also sending the nation’s sympathies to the Canadian people following the “horrendous tragedy” in Toronto.
A driver plowed a rented van along a crowded sidewalk in Toronto, killing 10 people and injuring 15 others. Trump says the nation’s hearts are with the grieving families in Canada.
___
9:25 a.m.
President Donald Trump says the “wonderful friendship” he has developed with French President Emmanuel Macron is a testament to two nations’ enduring alliance.
Trump is thanking Macron for his “steadfast partnership” in responding to the recent chemical attack in Syria.
The president is speaking at an arrival ceremony on the South Lawn of the White House.
Trump and Macron are meeting Tuesday on a number of issues, including the future of the Iran nuclear deal and the crisis in Syria.
The two leaders are holding a joint news conference later in the morning and then Macron will be honored with Trump’s first state dinner.
___
9 a.m.
President Donald Trump is welcoming French President Emmanuel Macron to the White House in a formal arrival ceremony.
The president and first lady are greeting Macron and his wife, Brigitte Macron, on rolled-out red carpet on the South Lawn.
The arrival is heavy on pomp, with nearly 500 U.S. service-members from all five military branches participating in the ceremonial welcome, which includes a “Review of the Troops.”
Vice President Mike Pence and several members of Trump’s Cabinet, lawmakers, and military families are in attendance. The audience includes students from the Maya Angelou French Immersion School in Temple Hills, Maryland.
The two leaders are spending the morning in meetings and then will hold a joint news conference. On Tuesday night, Macron will be feted at Trump’s first state dinner.
___
12:50 a.m.
A sit-down between President Donald Trump and French President Emmanuel Macron followed by a joint news conference highlight the business portion of the French leader’s second day in Washington.
The pageantry of Macron’s official state visit, the first of the Trump presidency, comes Tuesday night with a lavish state dinner at the White House. About 150 guests are expected to dine on rack of lamb and nectarine tart and enjoy an after-dinner performance by the Washington National Opera.
Monday night was more relaxed, featuring a helicopter tour of Washington landmarks and a trip to the Potomac River home of George Washington for dinner.
Pomp and ceremony aside, Trump and Macron disagree on some fundamental issues. A prime dividing point is the multinational Iran nuclear deal, which Trump wants to abandon. | George W. Macfarlane the journey from Honolulu to San Francisco and later rejoining them in Europe and the United States. In 1887, he accompanied Queen Kapiolani and the then-Crown Princess Liliuokalani to the Golden Jubilee of Queen Victoria. In 1888, he was appointed as Chamberlain of the Royal Household. With Robert Hoapili Baker, he accompanied the king on his final visit to the United States aboard the USS "Charleston", on November 1890. While visiting Southern California, the king drank excessively and fell ill in January 1891 and had to be returned to San Francisco. Hoapili and Macfarlane were at his deathbed at San | 1,999,723 | Hanna Reitsch Me 262, and Me 163. In 1959, Indian Prime Minister Jawaharlal Nehru invited Reitsch who spoke fluent English to start a gliding centre, and flew with him over New Delhi. In 1961, United States President John F. Kennedy invited her to the White House. From 1962 to 1966, she lived in Ghana. Kwame Nkrumah invited Reitsch to Ghana after reading of her work in India. At Afienya she founded the first black African national gliding school, working closely with the government and the armed forces. The West German government supported her as technical adviser. The school was commanded by JES | kathleen hanna was born on nov 12, what year | Mary Josephine Hannan | in which country did hannah more write reflections on the revolution | who was the first human to lift off the earth | what constituency did uhuru kenyatta serve as a member of parliament | Josephine Phelan | when did the 1001st helicopter land at the white house | where did paul kruger imported ministers and civil servants from |
1,999,724 | Comparison of Phosphate Treatment Technologies for Drum Type Boilers | Based on analysis to the property of phosphate precipitation, the controlling parameters of coordinated pH-phosphate treatment in boilers are presented. The temporary disappearance feature and troublesome problems existing in the said treatment applied to superhigh pressure boilers are discussed in detail. | Monopotassium phosphate was prepared with lowgrade phosphate rocks as material under microwave irradiation. Effect of sulfuric acid mass fraction,microwave irradiation,microwave power and phosphate grain size on monopotassium phosphate preparation was examined.The optimum experimental condition for monopotassium phosphate preparation by microwave was that mass fraction of sulfuric acid was 60%, microwave irradiation time 15min,microwave power 300 W and phosphate grain size 0.1mm.Under the optimum process condition,the yield of monopotassium phosphate was 88.6%. | Until recently, caustic water treatment was not used in high-pressure electric utility drum boilers in the United States because of concern over caustic gouging. Meanwhile, it was being used successfully in other countries. Many U.S. electric utilities have now converted their drum boilers to caustic treatment. This article describes the basics of caustic treatment and presents two case histories of successful use in the United States. | This paper describes the application of the fully automatic detection and control system for steam drum water level of the waste heat boiler for the 150t Converter of Baotou Iron and Steel Corporation:the drum water level is measured by means of capacitance intelligent drum water level meter working under all the conditions;the pressure in the water feed main pipe to steam drum is controlled by variable frequency water supply pump;the drum water level is controlled by feed water regulating valve;the fully automatic control of drum water level in various smelting stages is realized through software programming,so as to finally realize the accurate control of drum water level. | Dynamic characteristics of ortho-phosphate concentration in a UniTank process in Shanghai Shidongkou urban sewage treatment plant was studied by using a mathematical model basing on ASM2D. The results show that ortho-phosphate in the UniTank process is on non-steady state. Variation of the concentration of the species can be as large as 20%. Strengthening aeration may increase the nitrate-nitrogen concentration in the vessels, and interfere the anaerobic condition that is necessary for ortho-phosphate release from the phosphorus accumulating organism(PAO). This may result in the increase of the ortho-phosphate concentration in the effluent . | British Phosphate Commission back all the assets of the Pacific Phosphate Company for more than 3.5 million pounds on 1 July 1920, and started to manage it directly on 1 January 1921, after a six-month transition period of PPC management. Most of PPC's former employees were retained by the BPC. From 1919 the responsibility for the welfare of the people of Nauru and Banaba, the restoring of land and water resources lost by mining operations and compensation for environmental damage to the islands was under the control of the governments of United Kingdom, New Zealand and Australia. Under a policy established under the | To overcome the limitations of currently available protectives and consolidants for carbonate stones (such as marble and limestone), in 2011 the use of calcium phosphate was proposed. The idea is forming calcium phosphates (ideally hydroxyapatite) as the reaction product between the substrate and an aqueous solution of a phosphate salt, that the stone is treated with. In this paper, the studies aimed at identifying the best treatment conditions (in terms of nature and concentration of the phosphate precursor, solution pH, reaction time, ionic and organic additions) are first briefly summarized. Then, the efficacy of the phosphate treatment in protecting marble from dissolution in rain and restoring cohesion of weathered marble and limestone is discussed. Some recent studies on the use of the phosphate treatment on alternative substrates and some future steps for research on the topic are finally outlined. | The use of a solar furnace to produce elemental phosphorus by the reaction of phosphate rock, silica, and carbon has been demonstrated. All experimental runs were characterized by a considerable amount of impurities evolving from the reaction vessel at higher temperatures that condensed on the quartz window and other cooler surfaces. (LEW) | 1,999,724 | Treatment with phosphates has been the main mean of attemper the water for drum type boilers. The paper presents a concise critical review, in terms of checking indices, scope of application and influencing factors, of the development and application of phosphate treatment technologies during different historic periods, accompanied by a graphical representation of the relationship between concentration and pH valve of boiler water. | COORDINATED PH-PHOSPHATE TREATMENT IN BOILERS AND EXISTING TROUBLESOME PROBLEMS THEROF | Applied research on the clean production estimation index system in the phosphate mining | Effects of filter-paper adsorption and desorption on the spectrophotometric and radiochemical measurement of phosphate in filtered solutions | Appraising the phosphate removal capability of soil | what is not a concern with the use of phosphates | Model for Predicting the Concentration of Phosphorus Removed as Impurity during Hydro-Processing of Iron Oxide Ore Designated for Production of Orthopedics Devices | The phosphate supply system in the Pacific region | what is the toxicity of phosphates in dish detergent |
1,999,725 | but the result is an excellent read. His sense of the times and people ... | Starts strong, but in my opinion, it gets redundant. I enjoyed reading his points, and the book is certainly thought provoking. | Was enjoying the book until he started injecting his political views into everything....Kind of lost respect for him after that and skimmed over the remainder. | Enjoyed the read until the author got to his "coverage" of Gulf War 2. Then his agenda got pretty blatant that 1) he disagreed with the war (which he has every right to his opinion) but 2) that he was more about throwing mud on Bush and Blair than relaying his first-person experiences covering it. In fact, his bias got so blatant, I didn't finish the book. | This is a good read, he has a good understading of both sides of life, and the fact that you can apply yourself, and show your determination and stay focused, success follows! | I especially liked his explanation at the end of the book telling where his ideas came from. It was a riveting read. | Good except he tries to have all of the readers rally to the side of corrupt government, makes the book much less that it could be. Turns into a personal rant. | Great writing. He is a very intelligent writer I think and this was a good read all the way through. | I enjoyed reading about he visible Man's experiences, being an educated man, and the turmoil he endured living in 'the white world'!! | 1,999,725 | Alan Furst is a master. He develops the plot and the characters with care, a bit more slowly than some, but the result is an excellent read. His sense of the times and people he writes about is vivid, and evokes a certain nostalgia. A Dutch tramp freighter captain caught up in a war that takes control of his ship and his life. The war weary spy and the wandering female journalist, both of whom only want to escape the world that surrounds and controls them. Our captain tries to carry on in spite of the forces that draw him towards a climax in the cold waters of the Baltic. It is a dark voyage through troubled waters, and an icy peek into the souls of his protagonists. | Brad Thor is a great writer. All of his Novels are gripping action-packed ... | One of the best Furst novels. | Book Reviews: Robert A. Stafford, Scientist of empire: Sir Roderick Murchison, scientific exploration and Victorian imperialism | Characters in To The Lighthouse by Virginia Woolf | what type of book is wintersmith by terry pratchett | James Marsden typecasting... | Rail Wars Light Novel English | Scott Pratt is an outstanding mystery writer as good as any that have preceded him |
1,999,726 | I'm tired of trying to persuade people to invest into Crypto. Why do I have to convince ANYONE to better there own future. | Everyone on this sub loves it, I don’t understand too much about crypto. Why would you say I should invest in bitcoin and not other cryptocurrency?
EDIT: “Do yOuR oWn ReSeArCh” Comments are not helpful, please just answer why you think it’s the best crypto. I’m doing my own research, this is part of it. Thanks. I will not be buying crypto until I am more well versed. | Had it not been for cryptocurrency I would have not been able to buy more cryptocurrency. Ever since I was a kid, my dream was to own crypto and now crypto has finally enabled me to own crypto.
My farther and my grandfather always said “you have to hodl, don’t ever buy anything, CyberPunkMetalhead” so I went ahead and did that.
My long term goal is to own more crypto, and I think crypto will help me achieve that. | With Bitcoin currently near its all time high I see lots of people saying that it is too late to invest.
Although at such a high price it is risky in the short term, the long term prospects have never looked better.
We are currently seeing the start of mass adoption with major companies and institutions investing money into cryptocurrency.
But this is exactly that, the start! The majority of people and companies are still oblivious to the crypto world and that proves how much further the market can grow.
Yes maybe you didn't get here when bitcoin was $1000 but you are still an early adopter even if you invest now. | Recently I have been seeing new crypto users being shut down, and told not take anyone’s advice when it comes to crypto purchases. It makes a new crypto enthusiast like myself very hesitant to invest.
Imagine if you asked for stock market advice, and the most common response was “DON’T LISTEN TO ANYONE, DO YOUR OWN RESEARCH”. There are whole professions based around giving stock advice to people because it’s in such high demand. People are looking for guidance, whether it’s stocks or crypto (especially new users).
So what are the “good coins”, and what are the “bad coins”? It shouldn’t be a difficult question to answer, especially for those of you who have been closely observing the development of projects in the crypto market. | Hey guys,
FIRST I wish for you to make the most in this invesment and I do think cryptocurrency will contribute to the economic worldwide.
BUT I Really would like to hear from people here who owns bitcoins why they think it will fail.
Just to open our minds here | Yeah, I see a lot of videos stating they are making all this and that buy cloud mining or lending. but Straight to the point. To get the most out of crypto currency is to just invest money in it right? If you truly believe in the currency you are investing in. It should work in your favor? Where and how did all these millionaires come about.
I'm not trying to get rich, but I truly believe in a currency that can't be fucked with or regulated .
Please drop some knowledge on me. | Anyone can make a cryptocurrency. But very, very few people have the technical and mathematical know-how to make it secure, the business savvy to make it fly, and the persistence to keep it going. Basically, you need to come up with a fundamentally secure way for people to anonymously transfer wealth, come up with a way to make that wealth worth something, and convince a lot of people to go along with it. | Doesn't it look like "Let's copy/paste an existing crypto?"
* The GitHub repo seems very quiet, especially the README (7 pull requests ever only, 13 issues)
* Isn't the website very "generic". If I had to design a Wordpress crypto theme, I'd make it exactly like that
* Here you should be able to see the developers, well in fact, no, you can't
#11 on Coinmarketcap
Is there a real technical or marketing (or whatever) innovation in such a crypto?
___
Edit: if you know it, can someone cite the major new technical thing (solution to which problem and how do they solve it?) that NEM adds to cryptocurrency world to be ranked so high? | 1,999,726 | Hi folks, short rant here but I'm sure the people on this sub are a lot like me (I mean thats why you're on this sub in the first place-I hope) where they believe in crypto and what capabilities it has; and also how bullish the market is.
But I'm tired of feeling like I have to convince people to join the crypto community and invest!
The price of Bitcoin has risen from less than $1 to over $60,000 at it's ATH in less than a decade making some few lucky people, multi millionaires. Crypto has so much power and after that decade, people still don't understand that.
People should be rushing to us, and heck... even paying us to help them join the Crypto community as it could literally change their lives! But half the time, when I tell people I can help them invest, they don't even care.
Sorry for the rant, but I guess I just want everyone to know that we are the ones in power here and our knowledge is priceless.
Please remember, if it's not your keys, then it's not your coins! | Promote Bitcoin to your friends! | What's stopping me or anyone from making crypto currency (Bitcoins/Electronic Currency)? | A new community for crypto entrepreneurs and business owners | The Bullish News of Bitcoin Week 14, 2021 ! How to never sell your Bitcoin! | We are entering a new age that will revolve around blockchain and decentralization. And this is why I think the crypto market will explode. | Now is a great opportunity for the TRON community to step in and show some love to those hurting in r/cryptocurrency | Contrarian Analysis: Why crypto will surge during the next global recession. | What Is Your Number One Question About Making Money With Cryptocurrencies? |
1,999,727 | 37 Mircea Geoana conveys condolences to families of Beslan... | Brāļi mums ir apvienot un cīnīties pret anti brāļi
Mums ir jāstrādā kopā, lai
Mēs uzvarēsim kara brāļus | In this paper we consider new forms of memorialization – roadside memorials – in contemporary Russia which are similar to traditional forms functionally and pragmatically, but which have new dimensions at the same time. The roadside memorials at the places of sudden tragic deaths in urban and suburban environments reflect both individual and public contexts. This paper is based on our 2010-2013 field work in Tula and Vladimir Regions, also it includes a number of particular cases from another regions of Russia. During the field work we had observed 138 roadside memorials in 2010 and about 40 in the next years. We use the results of 37 interviews with people, involved in to the practice of spontaneous memorialization, undertakers, professional drivers, Orthodox priests. traffic police officers, road servicemen and local authorities. Finally we use the results of internet survey about the attitude towards roadside memorials, which include 80 respondents. Our main hypothesis states that Russian spontaneous memorials in general and roadside memorials particularly are less explicit and emphasize the performative or societal protest side of the practice. Mostly the construction of roadside memorials are a sign of transformation of mourning rituals in Russia from taking place only in institutionalized official place to taking place also in individualized spatial place. Normal 0 false false false RU X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ ::: table.MsoNormalTable ::: {mso-style-name:"Обычная таблица"; ::: mso-tstyle-rowband-size:0; ::: mso-tstyle-colband-size:0; ::: mso-style-noshow:yes; ::: mso-style-priority:99; ::: mso-style-qformat:yes; ::: mso-style-parent:""; ::: mso-padding-alt:0cm 5.4pt 0cm 5.4pt; ::: mso-para-margin-top:0cm; ::: mso-para-margin-right:0cm; ::: mso-para-margin-bottom:10.0pt; ::: mso-para-margin-left:0cm; ::: line-height:115%; ::: mso-pagination:widow-orphan; ::: font-size:11.0pt; ::: font-family:"Calibri","sans-serif"; ::: mso-ascii-font-family:Calibri; ::: mso-ascii-theme-font:minor-latin; ::: mso-fareast-font-family:"Times New Roman"; ::: mso-fareast-theme-font:minor-fareast; ::: mso-hansi-font-family:Calibri; ::: mso-hansi-theme-font:minor-latin;} | Ceremonies mark the end of mourning in the North Ossetian town of Beslan for victims of the school siege. | Daniele Bracciali sarà regolarmente in campo a partire dalle 15 sul centrale del Tc Alghero n... | Sănătăuca is a village in Florești District, Moldova.
References
External links
Villages of Florești District
Populated places on the Dniester | Avem 1361 de ventilatoare mecanice si 2653 paturi de terapie intensiva.
Deci dupa calculele mele grosolane, daca trecem de 10,000 de cazuri, trebuie sa dam cu banul sa vedem cine primeste ventilator si cine nu.
De aici: G4Media
Am pus postarea asta, pentru ca zilele trecute prezenta cineva o statistica (mincinoasa) din 2012 in care Romania avea 21.4 paturi ATI per 100 000 de locuitori.
Spun "mincinoasa", pentru ca la o populatie de 18 milioane, ar rezulta ca avem 3852 de paturi. | Rebrișoara () is a commune in Bistrița-Năsăud County, Transylvania, Romania. It is composed of four villages: Gersa I, Gersa II (both Gertia), Poderei (Szamosontuli) and Rebrișoara. The existence of the main village was first mentioned in 1440.
References
Communes in Bistrița-Năsăud County
Localities in Transylvania | I’m looking to get a tattoo in memory of my Ukrainian grandfather who died when I was young, so I wanted some help translating please!!
I want the tattoo to say ‘memories we have few, but my first is of you’
I’ve had a look on google translate and it doesn’t seem like there’s a straight translation, so any help with the correct wording / translation would be much appreciated. Thanks!! | 1,999,727 | Romanian Foreign Minister Mircea Geoana on Tuesday signed the condolence book opened at the embassy of the Russian Federation in Bucharest in memory of the victims of the terrorist attack in Beslan, North ... | Declaration of war by Saraliana on APCT | This book delivers and will help you understand your grief and sadness | This is a lovely book and I was so pleased to have found this Romanian language edition of this ... | Large But Disappointing Book On Ivory Coast Guro Art | who wrote the book be here now or remember, be now | This book brings back very sad and happy memories of going through losing my mother ... | how many lovers in almanac of the dead book | How to read Zatanna Seven Soldiers |
1,999,728 | who built the railway in wilde buenos aires | Buenos Aires Great Southern Railway manufactured in Britain, burned oil, a fuel in which Argentina was almost self-sufficient. Coal suitable for locomotive working was not available locally and had to be imported. The heaviest goods trains, reaching over 2000 tons during the harvest season, were often hauled by three-part articulated Garratt locomotives. When the entire Argentine railway network was nationalised in 1948, during Juan Peron's presidency, the BAGS became part of the General Roca Railway, one of the six divisions of State-owned Ferrocarriles Argentinos. At the same time the Roca Railway absorbed the former state-owned Ferrocarriles Patagónicos that included line from Carmen de Patagones to | Line B (Buenos Aires Underground) Abasto" (central wholesale fruit and vegetable market) was made available on 12 July 1933, by which goods wagons with freight from the "Ferrocarril Central de Buenos Aires" (Buenos Aires Central Railroad) would arrive, driven by electric locomotives. This was lifted after the fire occurred on 27 November 1952. From the beginning the circulation was protected by an automatic luminous signalization, with devices for mechanic trains, which were substituted in 1980 for others of magnetic induction, also replaced in 1998 for an electric system with ATP. Line B was recently extended underground further west (2 km) from Los Incas/Parque Chas to | Trolleybus usage by country Mendoza province, Argentina, had the first trolleybus operation in Latin America and one of the first in the world. South American Railless Traction Co., organized in London in 1912, planned to cover the continent with trolleybus lines and built an experimental route in Mendoza in 1913. (It was the only line that it built). In 1948 the Buenos Aires City transport authority purchased 120 trolleybuses from Westram, later in 1952 the Argentine government imported 700 new trolleybuses from Germany (350 Mercedes-Benz, 175 Henschel and 175 from Maschinenfabrik Augsburg Nürnberg). Most of the vehicles ran in the capital, Buenos Aires, but | year, the journal also described a ball that took place in the main hall of the station, offered by chiefs and officers in honor to the President on his birthday. History of rail transport in Paraguay In 1856 started the studies to make the first railroad of the country that would go from Asunción to Paraguarí. With the concession of the company to English hands the railroad extended to Encarnación. The beginnings of the train in America were in 1831 when, in the small town of Albania, United States appeared the steam train. On August 9 of the same year, | Transandine Railway Mateo Clark, Chilean brothers of British descent, successful entrepreneurs in Valparaiso who in 1871 built the first telegraph service across the Andes, between Mendoza in Argentina and Santiago in Chile. In 1874 the Chilean government granted them the concession for the construction of the rail link. Because of financial problems, their company, "Ferrocarril Trasandino Clark", did not begin work on the construction in Los Andes until 1887. The section between Mendoza and Uspallata was opened on 22 February 1891 and extended to Rio Blanco on 1 May 1892, to Punta de Vacas on 17 November 1893, to Las Cuevas on | Anglo-Argentine Tramways Company Philipp Holzmann being contracted by the AATC to undergo the works. When the line was opened on 1 December 1913, it became the first Underground line in the southern hemisphere, Latin America and the Spanish-speaking world. During the line's opening, the company's president Samuel Hale Pearson companied the Argentine vice president Victorino de la Plaza and the city's mayor Joaquín de Anchorena on the inaugural trip. The original Anglo-Argentine line ran underground from Plaza de Mayo in central Buenos Aires to the neighbourhood of Caballito, where it continued above-ground tram services through an access ramp at Primera Junta station, which | Andean Railway the three provinces of the Cuyo region, San Juan, San Luis and Mendoza with the city of Rosario, via the CAR. The AR was the first state-owned railway in Argentina and was founded on 15 November 1867 by decree promulgated in November 1867, from Villa María to Villa Nueva, then extending to Río Cuarto. At the beginning of 1870 the Government signed an agreement to British entrepreneur John Simmons who committed to finish the railway within 3 years at a cost of A$ 26,200 per mile. In November that same years works began. On October 24, 1873, the Villa María–Río | So my best friend and I are planning to travel to Argentina for a visit for 2 weeks this summer. We want to go to the southernmost city of Ushuaia first, probably by plane. I heard someone say that it is possible to take a boat along the coast from Ushuaia to Buenos Aires. I've heard that there are alot of scientific research ships or other boats that travel to and from Ushuaia. Has anyone had any experience or any suggestions on how to do this or any advice pertaining to travel in Argentina...? | 1,999,728 | Wilde, Buenos Aires two biggest railways, the Central Argentine Railway and the Buenos Ayres Great Southern Railway, were built, owned, and operated by the British. Both had headquarters in London and offices and stations in Wilde and Quilmes. They were started at the same time, but the Southern was made in sections, while the Central was planned as a great iron road to open almost of sparsely populated, rich land. A decree issued in August 1863 authorized the construction of the Southern, based on a proposal by a group of people that included the already mentioned wealthy Irish merchant Thomas Armstrong and George | what was the main problem with the buenos aires western railway | what was the name of the plan to build a tramway through buenos aires | how many tons of coal were hauled by the buenos aires great southern railway | when was the first state owned railway established in argentina | when was the andean railway started in argentina | who was the first president of the state owned railway company in argentina | what is the name of the subway system in buenos aires | when was the first tramway built in argentina |
1,999,729 | why is beryllium the only alkali metal not radioactive | What family is the Beryllium element found in? | What are berylliums uses? | Which element prbably has similar properties to beryllium? | All alkali metals have one valence electron. ... The attraction from the positive nucleus to the negative electron is less. This makes it easier to remove the electron and makes the atom more reactive. Experimentally speaking, cesium (caesium) is the most reactive metal. | What metals are in alkali? |
Introduction
Beryllium causes great interest for reactor and thermonuclear technology due to its unique neutronic features: low neutron absorption cross section and high moderating properties. Therewith, there are some problems for beryllium that restrict duration of its use as a part of nuclear facilities.
In the course of a reaction chain, gaseous nuclides such as 4 He, 3 He, 3 H, 1 H are produced on beryllium and primary reaction products, which cause the fission-gas-induced-swelling. In research reactor beryllium has to be replaced every 8-10 years, in fusion reactors it may need to be replaced every 5 years of operation [1][2][3].
The low beryllium content in nature shifts the focus on reprocessing of irradiated beryllium. Formation and accumulation of radioactive isotopes during beryllium irradiation is important in this process. Among them there are beryllium activation products ( 3 H, 10 Be) and impurity activation products in initial beryllium ( 137 Cs, 108m Ag, 60 Co, 14 C, 94 Nb).
The papers [2,4,5] are devoted to beryllium purification from radionuclides focusing on thermo desorption methods during tritium removal.
The article discusses safety ensuring issues during implementation of technology for beryllium purification from the cobalt, tritium, cesium and silver radionuclides, based on chemical transport reaction with gaseous chloride [6,7]. The purpose of this work is the safety justification during experiments at the irradiated beryllium purification unit
Irradiated beryllium sample specification
The discussed experimental research, which are directed to create an efficient technology for irradiated beryllium purification from radioactive isotopes, are implemented using beryllium that has been irradiated in Japanese Research Reactor JMTR in 1968-1975. Thermal neutron flux density during reactor running was 8.0•10 13 ncm -2 ·s -1 , fast neutron flux density was ~7.5•10 12 ncm -2 ·s -1 . Table 1 presents composition of radionuclides and its activity in beryllium sample with mass of 0.96 kg at the time of delivery (July 2009) and since the moment of research start (July 2018). We have found that radionuclides listed in the Table 1 represent major danger. For example, cobalt 60 Co, which is defined by the hardest gamma-irradiation and the second largest activity; tritium 3 H with maximum activity; silver 108m Ag -the second largest gamma-irradiation intensity and cesium 137 Cs, which is close in activity to 108m Ag. Table 2 provides radiation characteristics of these radionuclides.
Irradiated beryllium purification technology
The references [10,11] provided the information regarding possibility to use chemical transport reactions for beryllium, titanium and uranium purification, which proposed chemical transport involving halogenide -gaseous sodium chloride (Equation 1):
Be + 2NaCl (g) = BeCl2(g) + 2Na(g)
Production of high purity beryllium by beryllium oxide chlorination with carbon tetrachloride was considered in 1961 [12]. It was shown that such beryllium is feasible for in nuclear engineering without any additional purification.
A case in point is a chlorination of the above mentioned beryllium sample in gaseous chlorine medium, wherein its radionuclides (gamma-emitters 60 Co, 137 Cs, 108m Ag and 3 H beta-emitter) are converted into chlorides along with beryllium.
The technology of separation of beryllium and radionuclides is based on the differences in temperature limits of phase transformations of beryllium chloride and chlorides of radionuclides from solid (or liquid) to gaseous state (Table 3). Components of the technological process of irradiated beryllium purification from radionuclides, the main ones of which are the stages to produce beryllium chlorides, and their subsequent separation, are presented in Figure 1. Figure 1.The scheme of chloride production and separation (the phase state of the reagents is indicated geometrically: through a rectangle -solid, through an oval -gaseous).
When interacting with chlorine in the reaction chamber at a temperature of ~ 730°C, chlorides of radionuclides 60 Co, 137 Cs, 108m Ag and 3 H are generated along with beryllium chloride.
In the afterburner, unreacted chlorine in the reaction chamber is bound by hydrogen to form hydrogen chloride. Hydrogen is supplied in excess to completely eliminate the presence of chlorine in the reagent mixture. Due to the exothermic reaction, temperature of the reagents in the afterburner rises to ~ 800 °C, and then the mixture of chlorides and excess hydrogen is cooled in the heat exchanger to ~ 460 ° C Gamma-emitters (CoCl2, CsCl, AgCl) are deposited on a filter assembled from nickel rods, and beryllium chloride BeCl2 is deposited in a storage in the liquid phase as its temperature decreases to 420-480 °C.
Gaseous hydrogen chloride and tritium chloride enter the tritium chloride storage tank, where they dissolve in water to form hydrochloric acid.
Hydrogen gas is removed from the tritium chloride storage tank through the ventilation system. To implement the described technological process, an experimental plant has been designed.
In the considered technology of processing irradiated beryllium using chlorination, the following safety aspects can be highlighted:
-radiation safety; -toxic safety when handling beryllium and its compounds, chlorine and hydrogen chloride.
Radiation safety assurance
Protection of personnel from external exposure
The main method of protection from external exposure is to limit stay period of personnel in the radiation zone of the purifying plant.
Using the MCNP code [16], we calculated expected dose on the skin and the lens of a person's eye was estimated at its different positions relative to the beryllium sample in the variant of moving the person from the reaction chamber in perpendicular to the camera axis, where the beryllium sample is placed. The characteristics of the radiation of beryllium sample were taken in accordance with Table 1.
Based on the results of the calculation ( Figure 2) and the requirements [17] for the A and B-group personnel, the allowable duration of reaction chamber maintenance of the plant with the irradiated beryllium sample loaded into the reaction chamber was determined (Table 4). If we assume that the average distance of personnel from the chlorination unit during the work is 40-50 cm, and the time required to carry out work on treating one beryllium sample is 2 hours, then, according to the data in Table 5, during a year, the A-group personnel can perform 50 treatments of irradiated beryllium samples (the average frequency of work is 5 working days), being continuously close to the plant.
Protection from internal exposure.
Provided that the experimental plant is sealed during its operation, only tritium and tritium chloride can remain in gaseous form at all stages of the implementation of the technology for beryllium purification from radionuclides.
External exposure with tritium is not dangerous, since the maximum range of tritium beta-particles in air is 5.8 mm (at 20 ℃), and in biological tissue it is 6.5 μm. Therefore, beta particles of tritium are completely absorbed by the horny layers of the skin [18].
Tritium is dangerous if it enters the body through the skin, lungs or when eating and drinking water. Tritium can release from the beryllium purification plant in case of violation of its operation modes. The most dangerous is the release of tritium with water vapor (or water particles) from tritium chloride storage tank. This process can occur due to integrity destruction of the plant, opening the tank with stored mass of water and simultaneous abnormal overflow of water. Table 5 shows the main values of the quantities characterizing the limits of the intake of the average annual volume activity of tritium for tritiated water vapor and for gaseous tritium [17] based on the staff dose limit, which is 20 mSv. In the case of full release of gaseous tritium from the beryllium sample, its activity will exceed the annual intake limit (AIL), the volume activity of tritium in the air (~ 5.5 10 10 Bqm -3 at room volume ~ 200 m 3 ) will be significantly exceed the volume of permissible average annual volume activity (PVA).
Requirements for PVA non-exceedance is implemented if beryllium purification would be divided into several stages (not less than 13) with removal of accumulated tritium chloride at each stage. In this case, the requirements for non-excess of PVA will be met.
Then, even assuming that all tritium enters the room volume, its volumetric activity will not exceed ~ 4.3 × 10 9 Bq / m 3 . Taking into account the value of the annual volume of air inhaled by a person equal to 2.4 × 10 3 m 3 [19], and with an experiment duration of 2 hours, the maximum intake of tritium into the lungs of one employee during one cleaning will be 2.36 10 9 Bq, which exceeds the AIL.
Thus, in spite of the fact that estimates of the internal supply of tritium are conservative in nature, since a hypothetical case of the complete release of all tritium into the volume of the room in which the beryllium purification plant is located is considered, in order to ensure safety, it should be possible to exclude the presence of personnel in indoors during experiment.
Radiation safety during waste handling
As part of the purification plant, two main areas can be distinguished, where radioactive substances isolated from the sample of irradiated beryllium will be concentrated: chlorides in the solid phase on the surface of nickel filter rods; and tritium chloride dissolved in water in tritium chloride storage.
Chlorides of 60 Co, 108m Ag, 137 Cs and chlorides of less active radionuclides can be washed off nickel rods using their solvents (CoCl2, CsCl -water, methyl and ethyl alcohols; AgCl -aqueous solution of ammonia, cyanides, rodanides, alkali metal thiosulfates; pyridine and liquid ammonia). The resulting liquid radioactive solutions can be reprocessed for immobilization and preparation for long-term storage and subsequent disposal (evaporation, cementation, etc.). The gamma-emitter concentration in the waste from the surface of the filter will be higher than initial concentration in the beryllium rod. When handling these wastes, it is desirable to divide them into several parts to reduce the risk of personnel exposure.
When working with a solution containing tritium, the main danger lies in tritium release from the volume of the tank with the solution. The lowest maximum energy of beta particles 16 keV and the average energy 5.7 keV minimize the risk of handling the solution in the storage tank.
Toxic safety assurance
Safety assurance when handling beryllium and its compounds
When handling beryllium and its compounds, it is required to take into account their toxic properties [20].
The toxic properties of beryllium are manifested in relation to all human organs, but the most dangerous is the effect of beryllium on the lungs [21,22]. In terms of irradiated beryllium purification method under discussion, the most unfavourable from a hygienic point of view are processes with beryllium compounds vapor release and possible entry of beryllium vapors into the respiratory system of personnel, as well as the stages of method implementation, where beryllium chloride can potentially affect the skin of personnel.
The maximum permissible concentration of beryllium in the air of industrial premises is 1.0 μgm 3 [23], which is too low. In this regard, the work related with release of beryllium compound vapors should be carried out in specially equipped isolated rooms with combined extract-and-input ventilation so that the amount of extracted air exceeds the amount of input air by 15-20%. The work at the site for irradiated beryllium purification must be arranged in compliance with the requirements of the rules [23], including ventilation requirements of the plant and the process room, its regular wet cleaning, and obligatory use of individual protective equipment by the personnel.
Safety assurance when chlorine handling
Chlorine is a poisonous and dangerous gas. To ensure the safety of personnel, it is necessary to exclude the possibility of chlorine releasing outside hermetic volumes of the plant. The feeding of chlorine to the reaction chamber begins after preheating the beryllium with a heater mounted on the outer surface of the reaction chamber casing. The reaction rate varies with beryllium temperature.
The reaction is carried out with an excess of chlorine. Excess chlorine is neutralized by reacting with the hydrogen fed after the reaction chamber. The hydrogen feeding to the afterburner is carried out in an amount exceeding the stoichiometric one. Figure 3 presents a device for burning off chlorine residues. At the inlet of the cylinder-afterburner, there are holes for hydrogen feeding to the beryllium chloride stream and chlorine residues. Hydrogen with a temperature of 20 °C is fed through openings perpendicular to the flow of the gas mixture from the chlorinator.
Interaction between hydrogen and chlorine in general occurs according to the Figure 3.Chlorine residue burnout scheme. 1 -reagent dispenser; 2 -reactor chamber (chlorinator) casing; 3 -heater; 4 -holes for hydrogen feeding into mixer; 5 -mixer casing (afterburner); 6 -filter; 7 -interconnection joint of mixer and filter; 8 -flange connector.
Photochemical dissociation of chlorine molecules into atoms is caused by light with a wavelength of 550 nm. The activation energy of the first of these reactions is 25 kJmol -1 , and the second one is 8 kJmol -1 . Small values of these energies cause rapid development of the reaction as a whole.
In a mixture of chlorine and hydrogen, these reactions can take place too quickly, up to the explosion. When inert gases (e.g., nitrogen) are added to the mixture, the reaction rate slows down. One of the inert gas as in example in this technology is beryllium chloride. When the content of the active components comprises several percent, the explosive reaction is excluded.
The chlorine content at the chlorinator output depends on many parameters of its operation. It is essential that it does not exceed 10 mass percent, and 3-5% is optimal. In the latter cases, the heat of reaction (1) will be relatively small, and reliable control of the chlorine content in the beryllium chloride stream is ensured. The content of the components for these conditions in the considered direct-flow chlorinator is presented in Table 6. It follows from the above that, for safety purposes, the availability of an efficient method for measuring the amount of excess chlorine remaining after interaction with beryllium is of fundamental importance
The method for measuring chlorine content is based on the ability of chlorine to reflect light waves with a wavelength of 589.3 nm, due to which chlorine has a yellow-green colour, while the main component of the gas flow, which is beryllium chloride, is a transparent gas. A scheme for measuring chlorine concentration, based on its optical characteristics, is shown in Figure 4. Preliminary experiments confirmed the possibility to implement the proposed measurement scheme and the satisfactory accuracy of the results obtained in the operating range of the expected excess chlorine content.
The chlorine combustion process should be carried out with an excess of hydrogen. Otherwise, it becomes possible for chlorine to enter the tritium chloride storage tank. If a gas mixture with chlorine passes through the water of the tritium chloride storage tank, chlorine will actively interact with water to form hydrochloric acid and HClO4 (chlorine solubility in water reaches ~ 4.6 g per 1 liter of water at a water temperature of ~ 45 °C). Emission of chlorine into the atmosphere is excluded.
Conclusion
The following was considered as main risk factors:
-Radiation safety. The activities of radionuclides in irradiated beryllium were calculated during the work. The 60 Co gamma-emitter and 3 H beta-emitter pose the main danger from the used irradiated beryllium in 2018. With the extension of the work, 108m Ag gamma-emitter will pose a significant hazard.
The characteristics of the radiation situation were determined when working with the irradiated beryllium, taking into account the actual set of radionuclides (dose rates, permissible operating time)
The safe work of the A-group personnel is ensured with an annual processing of 50 rods of irradiated beryllium with a frequency of 1 week.
-Danger of chlorine emitting into the atmosphere. The elimination of chlorine emitting into the atmosphere is achieved by burning off the chlorine residues at the exit of the chlorinator site with hydrogen. Regulation of the burning process is carried out in accordance with the chlorine content at the output of the reaction chamber, measured by the reflected light flux in the spectral region with a wavelength of 589.3 nm.
Measurement of chlorine content by this method showed high accuracy. Possible residues of chlorine after burning out are dissolved in the water of the tritium storage tank.
-Risk of violation of thermal and hydraulic regimes: Cooling of the chamber of chlorine afterburner and sealing of the chlorination reaction chamber is provided with a stream of nitrogen.
The range of working content of chlorine residues at the reaction chamber outlet and the conditions for controlling the process of chlorine afterburning with hydrogen are determined.
Figure 2 .
2The dependence of the irradiation characteristics of human organs at the distance.
Figure 4 .
4Scheme for chlorine concentration measurement in the operating flow. 1 -photomatrix (or lux meter), 2 -lightfluxreflectedfromthegasmixture, 3 -lens, 4 -transparent casing of reaction chamber, 5 -gas mixture, 6 -light-emitting diodes, 7 -shield screen.
Table 1 .
1Specification of radionuclides in beryllium rod.Radionuclide
Nuclear reaction
Activity, Bq
July 2009
July 2018
3 H
9 Be (n,) 6 Li(n,)
2.510 11
1.510 11
55 Fe
54 Fe (n,)
4.510 6
0.4510 6
59 Ni
58 Ni (n,)
3.710 6
3.710 6
60 Co
59 Co (n,)
2.710 8
0.82710 8
108m
Ag
107m
Ag (n,)
2.410 7
2.2810 7
10 Be
9 Be (n,)
2.910 7
2.910 7
137 Cs
235 U (n, PD -)
1.810 7
1.4610 7
Table 2 .
2Radiation characteristics of 60 Co, 3 H, 108m Ag and 137 Cs [9].Nuclide
Type of
radiation
Radiation energy, MeV
T1/2, years
Decay, %
60 Co
γ
1.33251
5.27
99.9856
1.17323
99.9736
β
0.31788
100
108m
Ag
γ
0.4339
438.00
89.88
0.6144
90.39
0.7229
0.905
3 H
β
0.018594
12.28
100
137
Cs
γ
0.66165
30.17
89.98
β
0.5115
94.6
Table 3 .
3Chlorides melting and boiling temperatures[13][14][15].Chloride
CoCl2
BeCl2
CsCl
AgCl
HCl*
Tmelting, C
724
404
646
455
-114
Tboiling, C
1049
500±20
1302
1554
-85
*for standard conditions (25C, 100 kPa).
Table 4 .
4Permissible duration of work of the personnel of A and B groups when servicing the reaction chamber of the plant depending on the distance to the beryllium image.Distance, cm
Personnel A, h/year
Personnel B, h/year
1
1
0
5
5
1
42
133
33
80
437
109
100
608
152
Table 5 .
5Values of dose coefficients, limit of annual intake with air and permissible average annual volume activity in the air of individual radionuclides for personnel.Radionuclide
Half-decay
period
Type of
compound
during
inhalation
Dose
Coefficient,
Sv/Bq
Annual
intake limit
for person,
Bq per year
Permissible
annual volume
activity for
person, Bq/m 3
H-3
12.3 years
Water vapor
1.810 -11
1.110 09
4.410 05
Gaseous
tritium
1.810 -15
1.110 13
4.410 09
Table 6 .
6Content of BeCl2, Cl2и H2at afterburner inlet.Case
Chlorine in BeCl2, %
Flow rate, gs -1
BeCl2
Cl2
H2
1
3
6.984
0.21
0.006
2
5
6.839
0.36
0.010
3
10
6.479
0.71
0.020
AcknowledgmentThis work was carried out with the financial support of the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan State Institution under the Agreement 305 dated 03.30.2018 on the theme "Improving the method of irradiated beryllium dry purification".It is proposed to dilute possible hydrogen residues after reburning with inert argon (or nitrogen) at the gas flow outlet from the tritium chloride storage tank.Thus, it can be concluded that the work carried out at the irradiated beryllium purification installation is carried out taking into account the impact of harmful factors and compliance with all necessary measures, which ensures that there will be no harmful impact on the attendant personnel.
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| The fracture toughness of nuclear-grade hot-pressed beryllium after irradiation to fluences of 3.5 to 5.0 X 10 2 1 neutrons (n)/cm 2 (E > 1 MeV) was determined. Procedures and data relating to a round-robin test contributing to a standard ASTM method for unirradiated beryllium are discussed in connection with the testing of irradiated specimens. A porous grade of beryllium was also irradiated and tested, thereby enabling some discrimination between the models for describing the fracture toughness behavior of porous beryllium. The fracture toughness of unirradiated 2 percent beryllium-oxygen nuclear-grade beryllium was 12.0 MPa m 1 / 2 , which was reduced 60 percent upon irradiation at 339 K and testing at 295 K. The fracture toughness of a porous grade of beryllium was 13.1 MPa m 1 / 2 , which was reduced 68 percent upon irradiation and testing at the same conditions. Reasons for the reduction in fracture toughness upon irradiation are discussed. | What dos beryllium look like? | 1,999,729 | also have an even number of neutrons. Beryllium is the single exception to both rules, due to its low atomic number. All of the alkali metals except lithium and caesium have at least one naturally occurring radioisotope: sodium-22 and sodium-24 are trace radioisotopes produced cosmogenically, potassium-40 and rubidium-87 have very long half-lives and thus occur naturally, and all isotopes of francium are radioactive. Caesium was also thought to be radioactive in the early 20th century, although it has no naturally occurring radioisotopes. (Francium had not been discovered yet at that time.) The natural long-lived radioisotope of potassium, potassium-40, makes up | What are radioactive rare elements? | What is a type of radioactive decay that does not produce an atom of a different element? | what does the radioactive element berkelium cause in the body | Which nonmetal is radioactive and found in nature except with uranium metals? | Which of the following is a use l radioactive isotopes? | Why atom are radioactive? | What is the only element with atoms which o not have neutrons? | how many radioisotopes are there in the earth's soil |
1,999,730 | Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are severe and difficult-to-treat psychiatric illnesses with high rates of comorbidity. Although both disorders are treated with serotonergic based psychotropic agents, little is known on the influence of the serotonergic neurotransmitter system on the occurrence of comorbid GAD when clinically depressed. To investigate this poorly understood clinical question, we examined the involvement of frontolimbic post-synaptic 5-HT 2A receptors in 20 medication-resistant depressed (MRD) patients with half of them diagnosed with comorbid GAD with 123 I-5-I-R91150 SPECT. To explore whether 5-HT 2A receptor-binding indices (BI) associated with comorbid GAD could be related to distinct psychopathological symptoms, all were assessed with the symptom Checklist-90-Revised (SCL-90-R). MRD patients with comorbid GAD displayed significantly higher 5-HT 2A receptor BI in the hippocampal-amygdala complex, compared to MRD patients without GAD. Correlation analyses revealed that the 5-HT 2A receptor BI in these areas were significantly related to the SCL-90-R subscale hostility (HOS), especially for those MRD patients with comorbid GAD. Comorbid MRD-GAD may be characterized with increased hippocampal-amygdala 5-HT 2A receptor BI which could represent enhanced levels in hostility in such kinds of patients. Adapted psychotherapeutic interventions may be warranted.Keywords Major depressive disorder · Generalized anxiety disorder · Comorbidity · R91150 SPECT · serotonin 5-HT2A receptor |
| INTRODUC TI ON
Generalized anxiety disorder (GAD) is an anxiety disorder where the patient's excessive worry and anxiety significantly impair quality of life. Symptoms of GAD include restlessness, fatigue, irritability, and sleep disturbance (DSM, American Psychiatric Association, 2013).
GAD is common in adolescence and is associated with a relatively poor long-term prognosis (Pine et al., 1998). However, despite this, GAD, and particularly adolescent GAD, has been the focus of relatively little functional neuroimaging work.
A core feature of most anxiety disorders is hyper-responsiveness to threat. For example, both adolescents and adults with social anxiety disorder show increased responsiveness to social "threats" within the amygdala and connected cortical structures (e.g., Blair et al., 2008Blair et al., , 2016Gentili et al., 2016;Pine, 2001). Surprisingly, the literature is less clear cut with respect to GAD (for a review, see Fonzo & Etkin, 2017). There have been reports that adult patients with GAD, relative to comparison healthy individuals, show increased (e.g., Buff et al., 2017), comparable (e.g., Whalen et al., 2008) or decreased responsiveness (e.g., Blair et al., 2008Blair et al., , 2012. Findings with pediatric cases of GAD, though rarer, have been more consistent but indicate contextual importance (Fonzo & Etkin, 2017). For example, one study reported amygdala hyperactivity to faces but only if the participant was attending to their own subjective feeling of fear in response to the stimulus, rather than simply attending to the stimulus (McClure et al., 2007).
Potentially related to this literature on emotional responding, there have been suggestions that patients with GAD face difficulties in actively downregulating emotional responses to affective stimuli (Decker et al., 2008;Mennin et al., 2005;Patriquin & Mathew, 2017).
Active downregulation via cognitive reappraisal is thought to involve the volitional recruitment of regions implicated in top-down attention (dorsomedial, lateral frontal [dmFC and dlFC] and parietal cortices; Braunstein et al., 2017;Buhle et al., 2014). Consistent with this, two studies with adults with GAD have reported reduced recruitment of dmPFC and either lateral frontal or parietal cortices during cognitive reappraisal of emotional stimuli (Ball et al., 2013;Blair et al., 2012). Reduced emotional responding to emotional distracters is also seen as a result of volitional recruitment of regions implicated in top-down attention to task-related stimuli Mitchell et al., 2008;Pessoa et al., 2002). Adults with GAD also show reduced recruitment of dmPFC and parietal cortices in response to task-related stimuli in these paradigms and they do so during both implicit and explicit task instructions (Blair et al., 2012). However, the recruitment of top-down attentional regions during either cognitive reappraisal or task-related processing in the presence of emotional distracters has not, to our knowledge, been investigated in adolescents with GAD.
The goal of the current study was to investigate the responsiveness of neural systems engaged in responding to emotional stimuli, response control, and top-down attention during task-related processing in the presence of emotional distracters in adolescents with GAD. Thirty-five adolescents with GAD and a matched comparison group of 34 typically developing adolescents performed the Affective Number Stroop task , a task used previously within adults with GAD (Blair et al., 2012). During performance of this task, participants either perform goal-directed activity (counting the number of numerals) in the context of emotional or neutral distracters or simply process the emotional or neutral images (see Figure 1). The level of BOLD responses to negative relative to neutral stimuli allows an index of differential negative emotional reactivity at the neural level (i.e., the group-by-emotion interaction results). In line with previous work with adults with GAD on this task (Blair et al., 2012), we predicted the following: (i) adolescents with GAD would show evidence of: (i) reduced responsiveness to emotional stimuli (Group-by-Valence interaction) within the amygdala; and (ii) reduced recruitment of regions implicated in response control and top-down attention during task performance (Group-by-Task Condition interaction), that is, within dorsomedial and parietal cortices.
| ME THODS AND MATERIAL S
| Participants
Thirty-five adolescents with GAD and 34 healthy comparison individuals participated in the study. The two groups were matched on age, gender, and IQ (see Table 1). However, and consistent with the literature (Remes et al., 2018;Shen et al., 2018), 15 of the adolescents with GAD presented with comorbid major depressive disorder.
Clinical characterization was done through psychiatric interviews by licensed and board-certified psychiatrists with the participants and their parents, to adhere closely to common clinical practice.
Participants were recruited either shortly after their arrival at a residential care facility (Boys Town) or from the community. Youth recruited from the residential care facility were referred because of behavioral and mental health problems. The Boys Town youth are made up of participants with severe internalizing and externalizing pathology (sometimes co-occurring in the same youth). The participants in this study represented participants with severe internalizing pathology. Moreover, Boys Town is home to both males and females, with approximately 40% of the residents being female and our sample reflects that (of the 35 participants with GAD from Boys Town in the current study, 51% were female). The BT intervention involves a psychosocial residential treatment model with clinical contact with psychiatrists, clinical psychologists, and educational psychologists.
The model is heavily positive reinforcement-based and set within a rural environment to further reduce anxiety/threat. Medications are administered if felt appropriate though attempts are made to wean clients off over-prescription of medications that may have occurred preintake.
Community members were recruited via flyers. Participants were excluded if IQ was below 80 or if they had medical illnesses that required the use of medication that may have psychotropic effects, such as beta-blockers or steroids. Medications provided for psychiatric disorders (specifically antipsychotic, stimulant, or mood-stabilizing medications) were not exclusory but participants were asked to withhold medication on the day of the scan. Exclusion criteria also included braces, claustrophobia, active substance dependence (Boys Town routinely checks for substance use), pervasive developmental disorder, Tourette's syndrome, lifetime history of psychosis, neurological disorder, head trauma, non-English speaking, and presence of active safety concerns.
A doctoral level researcher or a member of the clinical research team obtained written informed consent and assent. In all cases, youth had the right to decline participation at any time before or during the study. Consent documents were reviewed with the parent/legal guardians and written permission was obtained (1) at the initial visit for community participants or (2) at the time of intake for youth placed in Boys Town programs. Assent was obtained from the Boys Town youth in a separate session. In all cases, youth had the right to decline participation at any time before or during the study. It was made clear to all participants and their parents that their decision with respect to participation had no influence on their clinical care. The Boys Town National Research Hospital institutional review board approved this study. Abbreviation: SCARED, Screen for Child Anxiety-related Disorders.
TA B L E 1 Subject characteristics
| Affective Number Stroop
The Affective Number Stroop task was adapted from prior work by our group (Blair et al., , 2019Hwang et al., 2016). The emotional stimuli consisted of 16 negative, 16 neutral, and 16 positive pictures selected from the International Affective Picture System (IAPS) (Lang & Greenwald, 1988). The individual cognitive task stimuli consisted of displays of numbers and the cognitive task involved deciding how many numbers were displayed in each display. Specifically, participants pressed button 3, 4, 5, or 6 to indicate whether there were 3, 4, 5, or 6 numbers in the display.
Each trial began with a fixation point presented in the middle of the screen for 400 ms. For trials involving a goal-directed task (task trials), the fixation point was replaced by an image presented for 400 ms, followed by the numerical display presented for 400 ms, followed by the image presented for a further 400 ms, followed by a blank stimulus for 1,300 ms. On incongruent or difficult task trials, the Arabic numeral distracter information was inconsistent with the numerosity information (e.g., four 5 s; see Figure 1a). On congruent task trials, the Arabic numeral distracter information was consistent with the numerosity information; (e.g., four 4 s; see Figure 1b). For the view or no task trials (view trials;
see Figure 1c), the numerical display was simply replaced by a fixation point.
There were two runs, each consisting of 16 presentations of each Valence-by-Task condition randomized throughout the run (i.e., 144 per run). In addition, 40 fixation points (staying on the screen for the duration of a condition trial 2,500 ms) were randomly presented throughout each run to serve as an implicit baseline. Thus, each participant was presented with 32 trials of each Valence-by-Task Condition across the two runs (288 task trial presentations, 80 fixation point trials).
| Anxiety measures
| fMRI parameters
Whole-brain blood oxygen level-dependent (BOLD) fMRI data were acquired using a 3.0 Tesla Siemens Skyra Magnetic Resonance Scanner. A total of 384 functional images were taken, divided over two runs, with a T2*-weighted gradient echo-planar imaging (EPI) sequence (repetition time (TR) = 2,500 ms, echo time (TE) = 27 ms, flip angle = 90°, field-of-view (FOV) = 240 mm). Whole-brain coverage was obtained with 43 axial slices (thickness, 2.5 mm; voxel size 2.6 × 2.6 × 2.5 mm 3 ; distance factor 21%). In the same session, a high-resolution T1-weighed anatomical image was acquired to aid with spatial normalization (MP-RAGE, repetition time = 2,200 ms, echo time = 2.48 ms; 230 mm field-of-view; 8° flip angle; 256 × 208 matrix) was acquired to register with the EPI dataset. Whole-brain coverage was obtained with 176 axial slices (thickness 1 mm; voxel size 0.9 × 0.9 × 1 mm 3 , distance factor 50%).
| fMRI Analysis: Data preprocessing and individual-level analysis
Functional MRI data were preprocessed and analyzed using Analysis of Functional NeuroImages (AFNI) software (Cox, 1996). Data from the first four repetitions were collected prior to magnetization equilibrium and were discarded. The anatomical scan for each participant was registered to the Talairach and Tournoux atlas (Talairach & Tournoux, 1988), and each participant's functional EPI data were registered to their Talairach anatomical scan in AFNI. Functional images were motion corrected and spatially smoothed with a 6-mm full width half maximum Gaussian kernel. The data then underwent time series normalization and these results were multiplied by 100 for each voxel. Therefore, the resultant regression coefficients are representative of a percentage of signal change from the mean.
Following this, regressors depicting each of the response types were created by convolving the train of stimulus events with a gamma-variate hemodynamic response function to account for the slow hemodynamic response. As such the model of the response began with trail onset and was modeled via a gamma-variate hemodynamic response function. There was no feedback provided in this study (participants were not informed if their responses were correct during task performance-only during practice outside the scanner).
Ten regressors depicting each of the response types were cre- Potential group differences in movement were analyzed via three one-way ANOVAs (for average motion per volume, censored volumes, and maximum displacement during scanning, respectively).
BOLD response data
We tested our hypotheses regarding GAD via a 2 (Group: Participants with GAD, participants without GAD) × 3 (Task Condition:
Follow-up analysis
Given the potential influences of medication use, the group-based ANOVA above was rerun excluding participants using, respectively, stimulants, antidepressant, and antipsychotics. Given the comorbidity of GAD with MDD, the group-based ANOVA above was rerun excluding participants with MDD.
Correction for multiple comparisons
We used a spatial clustering operation in AFNI's 3dClustSim utilizing the autocorrelation function (-acf) with 10,000 Monte Carlo simulations for the whole-brain analysis. Spatial autocorrelation was estimated from residuals from the individual-level GLMs. The initial threshold was set at p = .001. This process yielded an extant threshold of k = 20 voxels for the whole brain (multiple comparison corrected p < .05).
| RE SULTS
| Behavioral data
There were significant main effects of Task Condition for both ac- 2 p = 0.139) with healthy participants making less errors than participants with GAD (M HCacc = 88.42%; M GADacc = 78.54%). In addition, there was a significant Group-by-Valence interaction for the RT data (F(2, 134) = 6.20; p = .003; 2 p = 0,085). Healthy participants showed a significantly greater increase in RT in the presence of positive relative to neutral distracters than participants with GAD (t(67) = 3.47; p = .001; the results were in the same direction for negative relative to neutral distracters but only at weak trend levels -t(67) = 1.45; p = .152). There were no other significant effects involving group.
| Movement data
Volumes were censored if there was >0.5 mm motion across ad-
| EPI data
We tested our hypotheses regarding GAD via a 2 (Group:
Participants with GAD, participants without GAD) × 3 (Task All other significant results are listed in Table S1.
| Group-by-Task Condition interactions
The Group-by-Task Condition interaction identified regions including bilateral precentral gyrus, dmPFC, precuneus, and posterior cingulate cortex; see Table 2. In all 8 regions identified in the interaction, healthy individuals showed significantly greater activation compared to participants with GAD to both Congruent relative to View (F range 11.69-24.97; p < .001 for all) and Incongruent relative to View trials (F range = 14.66-33.76; p < .001 for all). This effect was driven by group differences to the Congruent and Incongruent trials rather than the View trials; Figure 2. Whereas there was no significant group difference to the View trials within any of the 8 regions (F range 0.00-2.27; ns), participants with GAD showed significantly less activation compared to the comparison individuals within all 8 regions to both Congruent (F range 6.00-18.90; p < range .05-.001) and Incongruent trials (except cuneus) (F range 7.10-18.46; p range .05-.001).
Follow-up analyses
1. Excluding participants using medications: Given the potential influences of medication use, the group-based ANOVA above was rerun excluding participants using respectively stimulants, antidepressant, and antipsychotics (See Table 1 ) Regions identified via the Group-by-Task Condition were proximal to those seen in the main analysis (Tables S2-S4).
Excluding participants with MDD: Given the comorbidity of GAD
with MDD, the group-based ANOVA above was rerun excluding participants with MDD (See Table 1). Regions identified via the Group-by-Task Condition were proximal to those seen in the main analysis (Table S5). In addition, comparisons between the participants with only GAD and those with GAD & MDD are included in the Supplemental Material.
| D ISCUSS I ON
The goal of this study was to investigate the responsiveness of neural systems engaged in responding to emotional stimuli and topdown attention during task-related processing in the presence of emotional distracters in adolescents with GAD. In line with predictions, adolescents with GAD showed reduced activity during task trials, relative to healthy adolescents, within regions implicated in motor (dorsomedial/bilateral precentral gyri and cerebellum) and attentional responding (posterior cingulate cortex, cuneus, and precuneus/superior parietal cortex). However, there were no indications of significantly heightened, or reduced, neural responsiveness to emotional stimuli in the adolescents with GAD.
The previous literature with respect to emotional/threat responsiveness is highly inconsistent with reports of adult patients with GAD showing, relative to comparison healthy individuals, increased (e.g., Buff et al., 2017), comparable (e.g., Whalen et al., 2008) or decreased threat responsiveness (e.g., Blair et al., 2008Blair et al., , 2012. Given our previous results with adults with GAD on this task (Blair et al., 2012), we predicted that adolescents with GAD might show evidence of reduced responsiveness to emotional stimuli within the amygdala.
However, this prediction was not confirmed. There were no significant group differences in BOLD responses to emotional stimuli in the current study (i.e., no regions showed Group-by-Valence interactions). There was, however, a significant Group-by-Valence interaction in the RT data; adolescents with GAD showed less slowing of RTs to task trials in the context of positive/negative distracters relative to neutral distracters relative to healthy participants. It is notable that previous work has shown that this slowing is exaggerated in patients with an anxiety disorder consistently associated with heightened threat responsiveness-post-traumatic stress disorder . The behavioral result at least is thus consistent with the suggestion that consistent worry in individuals with GAD may interfere with ongoing processing, including emotional processing (e.g., Blair et al., 2008;Ellis & Hudson, 2010).
In line with predictions, a series of regions showed significant Group-by-Task Condition interactions. These regions included dorsomedial and lateral frontal cortex, bilateral precentral gyri, cerebellum, posterior cingulate cortex, cuneus and precuneus/superior parietal cortex. These are all regions implicated in response control/ motor responding (bilateral precentral gyri and cerebellum; e.g., Scott, 2004) and/or cognitive control/attention (dorsomedial and lateral frontal cortex, posterior cingulate cortex, cuneus and precuneus/superior parietal cortex; see Leech & Sharp, 2014;Remington et al., 2020;Vogt, 2019). As seen in previous literature, the healthy comparison participants in the current study showed greater responses within these regions to task relative to view trials (see Figure 2). In contrast, the adolescents with GAD showed significantly less recruitment of these regions during task trials. Notably, the region of precuneus/superior parietal cortex that showed reduced activity in the adolescents with GAD in the current study was proximal to that showing reduced activity in the earlier work with adults with GAD using this task (Blair et al., 2012).
Moreover, and complimenting these BOLD data, the adolescents with GAD were significantly more inaccurate on this task relative to comparison adolescents. These findings are compatible with previous work reporting reduced executive function performance in patients Activations are effects observed in whole-brain analyses significant at p < .001, corrected for multiple comparisons (significant at p < .05).
TA B L E 2 Significant areas of activation from the 2 (Group: Participants with GAD, participants without GAD) × 3 (Task Condition: Incongruent, Congruent, View) × 3 (Valence: Negative, Neutral, Positive) ANOVA with GAD (Butters et al., 2011;Hallion et al., 2017;Stefanopoulou et al., 2014;Tempesta et al., 2013). Because of this reduced performance, the claim has been made that consistent worry in individuals with GAD interferes with ongoing processing-not only emotional processing but also executive functioning/task performance (e.g., Blair et al., 2008;Ellis & Hudson, 2010). Of course, this position remains unsatisfactory. Task-based analyses may be less useful in identifying the pathology associated with worry as opposed to the consequences of this worry.
Two caveats should be considered with respect to the current results. First, some participants with GAD were medicated. However, 3 follow-up group-based ANOVAs, excluding participants being medicated with stimulants, antidepressant, or antipsychotics, revealed group differences with respect to regions recruited during task performance that were proximal to the main analysis. As such,
we do not believe group differences in medication can account for the current results. Second, a number of the participants with GAD presented with comorbid MDD. This is consistent with previous work where the comorbidity of GAD with MDD is high (Remes et al., 2018;Shen et al., 2018). It is thus possible that the current results might represent the psychopathology of MDD rather than that of GAD. Importantly, however, a follow-up group-based ANOVAs, excluding participants with MDD again revealed group differences with respect to regions recruited during task performance that were proximal to the main analysis.
In conclusion, in the current study, participants with GAD showed reduced interference by emotional distracters in their behavioral performance (with respect to RT) and increased errors relative to healthy comparison adolescents. In addition, they showed reduced recruitment of a number of regions implicated in response control/motor responding and/or cognitive control/attention during task trials. Importantly, removal of participants taking stimulants, SSRIs, antipsychotics, or had MDD did not significantly change our findings after follow-up analyses. We hypothesize that these reflect is possible that these impairments reflect risk factors for the emergence of worry. funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
ACK N OWLED G M ENTS
CO N FLI C T O F I NTE R E S T
The authors have no conflicts of interest to disclose.
AUTH O R CO NTR I B UTI O N S
KSB and JBL are responsible for the data analysis. They both had full access to all the data in the study and take responsibility for the in-
PE E R R E V I E W
The peer review history for this article is available at https://publo ns.com/publo n/10.1002/brb3.1994.
DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request. The data are not publicly available due to IRB restrictions.
O RCI D
Johannah Bashford-Largo https://orcid. org/0000-0002-0128-9526
F
I G U R E 1 Task illustration. Example of (a) Negative Congruent, (b) Negative Incongruent, and (c) Negative View trial GAD (N = 35) Key to table.
for Child Anxiety Related Emotional Disorder(SCARED, child version, Birmaher et al., 1997) is a self-report questionnaire that looks at a youth's potential for having an anxiety disorder. There are 5 subsets including generalized anxiety disorder (9 questions) Panic Disorder (13 questions), Separation Anxiety Disorder (8 questions), Social Anxiety Disorder (4 questions), and School Anxiety (4 questions). Prior work has indicated that the SCARED has shown to have excellent internal consistency and test-retest reliabilities ( = 0.921 and r = 0.782 for random effects model)(Stringaris et al., 2012).
curacy and RT (F(1, 67) = 34.83 & 156.08 respectively; p = .002 & p < .001; 2 p = 0.342 & 0.700). As expected, participants were significantly more accurate and faster when responding to Congruent (M ac = 86.25%, M rt = 767.37 ms) relative to Incongruent trials (M acc = 80.57%, M rt = 827.63 ms), indicating that the task elicited the intended behavioral effects. There was also a significant main effect of group for error rates (F(1, 67) = 10.48; p < .05;
jacent volumes. No participant had >5% censored volumes. There were no significant group differences in terms of average motion per volume (M GAD = 0.082 vs. M HC = 0.083: F = 0.03; p = .865), censored volumes (M GAD = 0.429 vs. M HC = 1.088: F = 2.90; p = .093), or maximum displacement during scanning (M GAD = 3.202 vs. M HC = 3.322: F = 0.09; p = .767).
Condition: Incongruent, Congruent, View) × 3 (Valence: Negative, Neutral, Positive) ANOVA. In line with predictions, this revealed significant impacts of GAD on regions implicated in goal-directed activity (Group-by-Task Condition interactions; see below). However, no indications of specific heightened responses to threat were seen (i.e., no regions showing significant Group-by-Valence interactions).
secondary consequences of the increased worry shown by patients with GAD (c.f., Blair et al., 2008; Ellis & Hudson, 2010). culmen (x, y, z = −16, −58, −16); (d) left posterior cingulate gyrus/culmen (x, y, z = −7, 40, −1) (p < .001 for each)
Health under award number K22-MH109558 (JB). The
tegrity of the data and the accuracy of the data analysis. JK, KM, and SW contributed to the acquisition and critical revision of the manuscript. JBL, JA, MD, RJR, and KSB contributed to interpretation of the data and critical revision of the manuscript for important intellectual content.
Volumes were censored if there was >0.5 mm motion across adjacent volumes. No participant had more than 5% censored volumes.ated (Negative View, Negative Congruent, Negative Incongruent,
Neutral View, Neutral Congruent, Neutral Incongruent, Positive
View, Positive Congruent, Positive Incongruent, and Error/Missed
Responses). Linear regression modeling was then performed using
the regressors described above plus regressors to model a fourth-or-
der baseline drift function. This produced for each voxel and each
regressor, a beta coefficient and its associated t-statistic.
2.6 | Statistical analyses performed
2.6.1 | Behavioral data
Accuracy and reaction time (RT): Accuracy and RT data were ana-
lyzed via two 2 (Group: Participants with GAD, participants without
GAD) × 2 (Task Condition: Congruent, Incongruent) × 3 (Valence:
Negative, Neutral, Positive) repeated measures ANOVAs.
2.6.2 | fMRI data
Movement data
Note: coordinates based on the Tournoux & Talairach standard brain template, BA = Brodmann's Area, R = Right, L = Left.REGION
BA
Voxels
X
Y
Z
F-value
eta
R Precentral
Gyrus
6
52
29
−16
59
16.54
0.263
L Precentral
Gyrus
4
36
−19
−22
62
12.24
0.254
L Postcentral
gyrus/Precuneus
6
21
−49
−4
23
11.80
0.286
R dmPFC
6
26
2
−13
65
10.30
0.226
L Posterior
cingulate gyrus/
culmen
30
344
−7
40
−1
15.56
0.228
R Cuneus
18
75
11
−73
20
12.26
0.324
R Precuneus
7
22
17
−52
56
10.50
0.205
L Cerebellum
63
−16
−58
−16
16.50
0.149
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| Generalized anxiety disorder (GAD) is poorly diagnosed and inadequately treated by general practitioners. The paper considers the major diagnostic signs of GAD, its differential diagnosis, prevalence, etiology, and pathogenesis. Antidepressants from a group of selective serotonin reuptake inhibitors in combination with psychotherapy are the drugs of first choice. |
Introduction
The dorsal raphe (DR) is a serotonergic (5-HT) midbrain nucleus that is highly implicated in the etiology of several mood disorders, including depression (Jans et al. 2007;Olivier 2015). The activity of this nucleus is critically regulated by 5-HT 1A receptors, which, upon stimulation, activate G protein-coupled inwardly rectifying K + (GIRK) channels, leading to a reduction in membrane excitability and an inhibition of action potentials (Aghajanian and Lakoski 1984;Bayliss et al. 1997). In addition to 5-HT 1A receptor-mediated regulation, the GABAergic system also provides inhibitory control of local DR activity and descending excitatory inputs (Gervasoni et al. 2000;Celada et al. 2001;Varga et al. 2001Varga et al. , 2003Amat et al. 2005;Challis et al. 2014).
Recently, emerging evidence has shown that GABA A and GABA B receptor-mediated neurotransmissions of the DR are highly involved in drug-related stress, aggression, social avoidance, abnormal responses to social stimulation, and stress-related psychiatric disorders, such as depression (Takahashi et al. 2010(Takahashi et al. , 2012Challis et al. 2013;Araki et al. 2016;Li and Kirby 2016). In addition, the manipulation of 5-HT 1A autoreceptors in the DR affects 5-HT neuronal firing, determines the responsiveness to stress in depressionrelated tasks and alters behavioral responses to antidepressant drugs in mice (Richardson-Jones et al. 2010). Interestingly, the recent phenotypic and electrophysiological characterization of GIRK2 knockout mice revealed that the mutation promotes depression-resistant behavior, reduced antidepressant responses, increased 5-HT neuronal firing, and decreased 5-HT 1A receptor activity in the DR in vivo . Although it was reported that GIRK channels located in the DR are coupled to 5-HT 1A and GABA B receptors (Innis et al. 1988;Williams et al. 1988), little is known regarding the contribution of these effectors to 5-HT 1A , GABA B , and GABA A receptormediated transmissions in the DR and whether manipulations of GIRK channels cause alterations in these pathways related to the pathophysiology of depression. Therefore, we sought to investigate in vitro, the contribution of GIRK2 subunit-containing channels on the basal properties and tonic activity of DR neurons and their impact on 5-HT 1A , GABA B , and GABA A receptor-mediated transmission in the DR microcircuit.
Methods
Ethical approval
The animals used in this study were GIRK2 knockout mice (GIRK2 KO mice; n = 35) and their wild-type littermates (WT; n = 45) (4-8 weeks old) derived from heterozygote crossing in a C57BL6/J background. Mice were maintained at 22 AE 2°C in a 12-h light/dark cycle with food and water provided ad libitum. The genotype was verified by PCR screening of genomic DNA at the Department of Neurochemistry Research of the Basque Health Service (Zamudio, Spain). Every effort was made to minimize the animals' suffering and to minimize the number of animals used. All procedures were conducted in accordance with the European Community Council Directive on "The Protection of Animals Used for Experimental and Other Scientific Purposes" (2010/63/EU) and Spanish Law (RD 53/2013) for the care and use of laboratory animals. Experimental protocols were approved by the Local Committee for Animal Experimentation at the University of the Basque Country (permit numbers 44-P04-01/2010 and 44-P04-03/2010).
Electrophysiological recordings
Slice preparation
Whole-cell patch-clamp recordings were performed as previously described (Gantz et al. 2015). Mice were anesthetized with isoflurane and killed via decapitation. Immediately afterward, the brains were removed and mounted in a vibratome chamber (Leica VT 1200S). The DR was located in slices that were rostral to the level where the aqueduct begins to meet the fourth ventricle and caudal to the decussation of the cerebellar peduncle. Coronal slices (220 lm) were prepared in ice-cold artificial cerebrospinal fluid (ACSF, external bath solution) containing the following (in mmol/L): 126 NaCl, 2.5 KCl, 1.2 MgCl 2 , 2.6 CaCl 2 , 1.2 NaH 2 PO 4 , 11 D-glucose, and 21.4 NaHCO 3 . ASCF was oxygenated and maintained at pH 7.4 by bubbling with 95% O 2 /5% CO 2 gas. Slices were stored in glass vials at 34°C with oxygenated (95% O 2 /5% CO 2 ) ACSF. To reduce neuronal damage, MK-801 (10 lmol/L) was included in the cutting and initial incubation solution to block NMDA receptors. After an incubation period of at least 40 min, slices were transferred to the recording chamber for recording.
Electrophysiological recording
Slices containing DR were mounted on a recording chamber attached to a microscope (Eclipse FN1; Nikon) and continuously perfused with ACSF at 1.5-3 mL/min at 32-34°C maintained using an in-line solution heater (TC-324; Warner Instruments, Hamden, CT). Only neurons that were located on the midline with a large cell body and that met the previously reported properties of tryptophan hydroxylase positive, non-GABAergic DR neurons in mice, were included in this study (Gocho et al. 2013;Levitt et al. 2013).
Recording pipettes pulled from glass capillaries (1.7-3 MΩ; World Precision Instruments) were used for all the experiments. To record the passive and active membrane properties and 5-CT-and baclofen-induced currents, electrodes were filled with an internal solution containing the following (in mmol/L): 130 K-gluconate, 5 NaCl, 1 MgCl 2 , 1 EGTA, 10 HEPES (K), 2 Mg-ATP, 0.5 Na-GTP, and 10 Na 2 -phosphocreatine (pH: 7.3-7.4, 280 mOsm). To record the spontaneous and evoked inhibitory postsynaptic currents (sIPSCs and eIPSCs), electrodes were filled with the following internal solution (in mmol/L): 70 K-gluconate, 70 KCl, 2 NaCl, 4 EGTA, 10 HEPES (K), 4 Mg-ATP, 0.3 Na-GTP, and 10 Na 2 -phosphocreatine (pH: 7.3-7.4, 280 mOsm). DNQX (10 lmol/L) was added to the external solution (ACSF) to block AMPA/ kainate receptors. Cells were voltage-clamped at À70 mV using a Multiclamp 700B amplifier (Molecular Devices (UK), Wokingham, UK). Signals were digitized using a Digidata 1440A (Molecular Devices) analog-to-digital converter. Data were acquired using pClamp 10 software (sampled at 10 kHz, filtered at 5 kHz) and were post hoc filtered (Molecular Devices). Series resistance was monitored without compensation with 5 mV depolarizing steps (200 msec) induced every 60 sec to ensure sufficient electrical access to the cell (<15 MΩ for inclusion).
Immediately after gaining access, the membrane capacitance, input resistance, and resting membrane potential (I = 0) were measured using the Clampex application of pClamp 10 software. Next, in current-clamp mode, action potentials were elicited by applying currents from 0 to 200 pA in 50 pA steps (2 sec per step), and the action potential properties were determined. For the currentvoltage (I/V) analysis, voltage steps were applied. Under this protocol, the presence of an inwardly rectifying K + (IRK) current could be detected according to the typical current-voltage relationship obtained when the membrane potential was hyperpolarized from À60 to À130 mV (À10 mV increments, 100 msec per step), as described by Williams et al. (1982). Activation of GIRK currents induced by 5-CT was detected using the I/V protocol before and during drug application.
To study sIPSCs, the basal spontaneous activity of the cell was recorded for at least 3 min when the recording reached a steady and stable state. A paired-pulse protocol was used to examine the eIPSCs. A monopolar stimulating electrode was positioned 100-200 lm dorsolateral to the cell being recorded, and pairs of electrical stimuli (100 lsec at 20 Hz, 100-msec interpulse interval, 20-sec interpair interval) were delivered using an Iso-Flex stimulus isolator (A.M.P.I.). The liquid junction potential between the pipette internal solution and the ACSF was 15 mV and was not corrected.
Electrophysiological data analysis
Analyses were carried out off-line using the Clampfit application of pClamp 10 software. To calculate the effect of 5-CT, baclofen, and GABA on the whole-cell currents of the DR cells, the amplitude of the currents induced by these drugs was measured when the maximal effect was reached only in those cells where there was a complete washout after drug application. A 30-sec period was taken for the off-line analysis of frequency, amplitude, rise time, and decay time of the sIPSCs for each experimental condition (before or during drug application). Single peak sIPSCs were detected using a semiautomated sliding template detection procedure (Clampfit 10.3 software). The template was generated by averaging multiple spontaneous currents, and the selection was fitted to four thresholds of the template. Each detected event was visually inspected and discarded if the amplitude was <7 pA.
The rise and decay times were determined by measuring the time between the currents crossing 10% and 90% of the baseline-to-peak amplitude range during the rise stage and decay stage of the event, respectively.
The amplitude of eIPSCs was calculated by measuring the average current at the peak of each evoked event and subtracted from the current obtained during the 10 ms window taken immediately before the stimulus artifact. To obtain the paired-pulse ratio, the amplitudes of IPSC1 and IPSC2 were averaged for at least six sweeps (120 sec), and the ratio was calculated for each cell. By analyzing the paired-pulse ratio, we detected if there was a paired-pulse facilitation or depression pattern in each DR cell, which is related to changes in the probability of GABA release (Bonci and Williams 1997;Manzoni and Williams 1999).
Drugs
The chemicals used to make the ACSF were purchased from Panreac or Merck. Mg-ATP, Na-GTP, and phosphocreatine disodium salt hydrate for the internal solution were obtained from Sigma-Aldrich. Stock solutions of 5-CT (5-carboxamidotryptamine maleate salt; Sigma-Aldrich, Madrid, Spain), baclofen [(R)-4-Amino-3-(4-chlorophenyl) butanoic acid; Abcam, Cambridge, UK], CGP55845 (CGP55845 hydrochloride; Abcam, Cambridge, UK), GABA (4-aminobutanoic acid; Abcam), tertiapin-Q (Tocris, Bristol, UK), and WAY100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate salt; Sigma-Aldrich) were prepared in distilled water. DNQX [6,7-dinitroquinoxaline-2,3-dione; Abcam] and MK-801 [(+)-MK-801 maleate; Abcam] were prepared in DMSO (dimethyl sulfoxide). Drug stocks were diluted in artificial cerebrospinal fluid (ACSF) immediately before application. The highest experimental concentration of DMSO was 0.01%. Isoflurane was purchased from Abbott.
Statistics
Statistical analyses were performed using GraphPad Prism Software (v.5.01; GraphPad Software Inc., La Jolla, CA). Values are given as the means AE SEM. All data sets with n > 30 were tested for normality using a one-sample Kolmogorov-Smirnov normality test. If any data set failed the normality test, nonparametric tests were used. The statistical analysis for within-group comparisons was performed using paired two-tailed t-tests or a two-way repeated measures (RM) ANOVA followed by Bonferroni multiple comparisons post hoc test. Between-group significant differences were determined using unpaired two-tailed t-tests, two-tailed Mann-Whitney U tests, or a two-way ANOVA followed by Bonferroni multiple comparisons post hoc test. Fisher's exact test was used to compare the paired-pulse ratio pattern. Correlations were determined using two-tailed Pearson correlation. To determine whether the cumulative probability plots of the frequency and amplitude of sIPSCs were different between groups, the two-sample Kolmogorov-Smirnov test was used. A difference of P < 0.05 was considered significant.
Results
Role of GIRK2 subunit-containing GIRK channels in the electrophysiological properties of DR neurons
To examine the contribution of GIRK2 subunit-containing GIRK channels on the electrophysiological properties of DR neurons, we inspected the intrinsic membrane properties and action potential (AP) properties in GIRK2 KO mice. As shown in Table 1, we observed a more depolarized resting membrane potential (P = 0.0318, Mann-Whitney U test) and a higher input resistance (P = 0.0113, unpaired two-tailed t-test) in GIRK2 KO mice compared to WT mice. In current-clamp mode, injection of current produced slow and regular firing of long-duration AP that increased in frequency upon larger current injections in both genotypes (F 1,228 = 558.6, P < 0.0001, two-way RM ANOVA; Fig. 1A). As shown in Figure 1B, the genotype had no effect on the sensitivity of DR neurons to the injected currents (F 1,228 = 0.8321, P = 0.3655, two-way RM ANOVA). Analysis of the AP properties revealed that the DR neurons of the GIRK2 KO mice had shorter AP halfwidth (P = 0.0344, unpaired two-tailed t-test; Table 1) and AP decay time (P = 0.0175, unpaired two-tailed t-test; Table 1). Similarly, the application of the GIRK channel blocker tertiapin-Q (1 lmol/L) during 5 min in WT mice depolarized the resting membrane potential (P < 0.0001, paired two-tailed t-test; n = 19 cells), reduced the AP decay time (P = 0.0115, paired two-tailed t-test; n = 11 cells), and increased the AP rise time (P = 0.0219, paired two-tailed t-test; n = 11 cells) without altering the AP half-width (P = 0.3849, paired two-tailed t-test; n = 11 cells). Moreover, tertiapin-Q increased the sensitivity of DR neurons to the injected currents (F 1,77 = 49.18, P < 0.0001, two-way ANOVA; n = 11 cells; Fig. 1C and D), being the AP frequency after 100, 150, and 200 pA current injections statistically greater after the application of tertiapin-Q (P < 0.05 for 100 pA current injections and P < 0.001 for 150 and 200 pA current injections, Bonferroni post hoc test; n = 11 cells). In summary, these results indicate that both the genetic or pharmacological blockade of GIRK channels depolarizes the membrane potential. In addition, the genetic inactivation of GIRK channels increases the membrane resistance and reduces the duration of action potentials of DR neurons.
Decreased 5-HT 1A and GABA B receptormediated postsynaptic currents in DR neurons of GIRK2 KO mice To evaluate whether the 5-HT 1A receptor-mediated postsynaptic transmission in DR neurons is affected by Girk2 gene inactivation, we measured the somatodendritic currents evoked by 5-CT, a high-affinity full agonist of 5-HT 1A receptors, in DR cells of GIRK2 KO mice. Whole-cell voltage-clamp recordings performed in WT mice revealed that the application of 5-CT (0.1 lmol/L) elicited outward currents that were markedly reduced in the GIRK2 KO mice (P = 0.0004, unpaired two-tailed t-test; Fig. 2A and B). Voltage steps (À60 to À130 mV, 100 msec) were applied to determine the identity of the 5-CT-induced outward currents before and during drug application. The current produced by 5-CT at each voltage was determined by subtracting the corresponding control current at baseline conditions, before the bath application of 5-CT. Consistent with the activation of GIRK channels, the 5-CT-induced current displayed inward rectification in WT but not in GIRK2 KO animals. This is shown as the change in the slope of the current-voltage relationship, which was more pronounced at more hyperpolarized potentials ( Fig. 2A and C). Moreover, application of tertiapin-Q (1 lmol/L) before 5-CT completely blocked the outward currents induced by this drug in the WT mice (P < 0.0001, paired two-tailed t-test; Fig. 2D and E).
In addition to 5-HT 1A receptors, GIRK channels are coupled to GABA B receptors in the DR. Thus, in the second set of experiments, we studied the effect of Girk2 gene ablation on the somatodendritic currents induced by the GABA B receptor agonist baclofen. Application of baclofen (30 lmol/L) elicited outward currents in WT that were statistically reduced in the GIRK2 KO mice (P < 0.0001, unpaired two-tailed t-test; Fig. 3A and B). Similarly, the baclofen-induced currents were completely absent when tertiapin-Q was previously applied in WT mice (P = 0.0008, paired two-tailed t-test; Fig. 3C and D). Taken together, these data indicate that GIRK channels, and specifically those containing GIRK2 subunits control the 5-HT 1A and GABA B receptor-mediated postsynaptic currents in the DR.
Decreased GABA release in GIRK2 KO mice
Next, we examined whether Girk2 gene inactivation alters presynaptic and postsynaptic GABA A receptor-mediated neurotransmission in the DR. To study the presynaptic GABA A receptor activity, we assessed GABA release in GIRK2 KO mice using two well-established methods. The first method was the paired-pulse stimulation protocol. In synapses with low release probability, the second release is enhanced due to residual calcium in the presynaptic terminal, and changes in neurotransmitter release affect the paired-pulse ratio (Khazipov et al. 1995;Bonci and Williams 1997;Stanford and Cooper 1999;Sullivan 1999;Melis et al. 2002). As shown in Figure 4A, in cells from WT mice, the second eIPSC (IPSC2) was generally smaller than the first eIPSC (IPSC1), indicating depressing synapses, and cells from GIRK2 KO displayed a larger IPSC2 compared to IPSC1, which is characteristic of facilitating synapses with low probability of release. Thus, the proportion of cells that exhibited depressing synapses was significantly reduced in the GIRK2 KO mice (P < 0.0001, Fisher's exact test), and the paired-pulse ratio in the GIRK2 KO mice was larger than in WT mice (P = 0.0223, unpaired two-tailed t-test; Fig. 4B). The numbers of cells exhibiting facilitation and depression are illustrated in Figure 4C. Importantly, the paired-pulse ratio did not depend on the size of IPSC1 for any genotype (P = 0.4049 for WT, P = 0.5849 for GIRK2 KO, two-tailed Pearson correlation; Fig. 4D). Additionally, the effect of tertiapin-Q on the paired-pulse ratio was inspected. As shown in Figure 4E and F, application of tertiapin-Q increased the paired-pulse ratio in WT mice (P = 0.002, paired two-tailed t-test) but not in the GIRK2 KO mice (P = 0.9855, paired two-tailed t-test).
The second method that we used to examine GABA release in the GIRK2 KO mice was assessing sIPSC frequency. The frequency of the sIPSCs of the GIRK2 KO mice was significantly lower than the sIPSCs of WT mice (P = 0.0062, unpaired two-tailed t-test; Fig. 5A and B). Thus, the cumulative probability plot of the interevent interval was shifted significantly to the right for the GIRK2 KO mice (P < 0.01, K-S test; Fig. 5C). In addition, the sIPSC amplitude of the GIRK2 KO mice exhibited a decrease compared to that of the WT mice (P = 0.0001, two-tailed Mann-Whitney U test; Fig. 5D). This reduction was confirmed by a shift to the left in the cumulative probability plot of amplitudes (P < 0.01, K-S test; Fig. 5E). The analysis of the kinetic parameters revealed that the rise time was greater in the GIRK2 KO compared to WT mice (P = 0.01, unpaired two-tailed t-test; Fig. 5F) but the decay time was not different (P = 0.5212, unpaired two-tailed t-test; Fig. 5G).
These results demonstrate that GIRK2 KO mice have a decreased spontaneous probability of GABA release and a reduced number and/or sensitivity of postsynaptic GABA A receptors.
Moreover, both the genetic and pharmacological blockade of GIRK channels cause a decrease in the evoked probability of GABA release.
Diminished control of presynaptic 5-HT 1A and GABA B receptors over GABA release in GIRK2 KO mice
One physiological function of inhibitory G proteincoupled receptors (GPCRs), which activate GIRK channels, is the inhibition of presynaptic neurotransmitter release (Thompson et al. 1993;Wu and Saggau, 1997). Therefore, we examined whether the presynaptic inhibition of GABA release was altered in GIRK2 KO mice.
In the first set of experiments, we evaluated the control of presynaptic 5-HT 1A receptors over GABA release in the DR neurons of GIRK2 KO mice. WAY100635 was perfused (1 lmol/L, 10 min), and the frequency of sIPSCs was inspected. In addition, we studied the amplitude, rise time, and decay time of sIPSCs before and during the application (Fig. 6A). WAY100635 increased the frequency of sIPSCs in WT mice (P = 0.0094, paired two-tailed t-test; Fig. 6B, inset histogram) but not in GIRK2 KO mice (P = 0.6748, paired two-tailed t-test; Fig. 6C, inset histogram). This effect is reflected as a significant shift to the left of the cumulative probability plot of the interevent interval for WT mice (P < 0.01, K-S test; Fig. 6B) but not for GIRK2 KO mice (P = 0.7223, K-S test; Fig. 6C). Furthermore, WAY100635 increased the amplitude of sIPSCs in both WT (P = 0.0420, paired two-tailed t-test; Fig. 6D, inset histogram) and GIRK2 KO mice (P = 0.0294, paired twotailed t-test; Fig. 6E, inset histogram), represented as a shift to the right in the cumulative probability plot of amplitudes for WT mice (P < 0.01, K-S test; Fig. 6D) and for GIRK2 KO mice (P = 0.01, K-S test; Fig. 6E). The analysis of the effect of WAY100635 on the rise time of sIPSCs revealed that it had no effect on both WT (P = 0.4293, paired two-tailed t-test; Fig. 6F) and GIRK2 KO mice (P = 0.2674, paired two-tailed t-test; Fig. 6F). In the WT mice, WAY100635 induced a significant increase in decay time (P = 0.0145, paired two-tailed t-test; Fig. 6G) that was not observed in the GIRK2 KO mice (P = 0.2356, paired two-tailed t-test; Fig. 6G).
In the second group of experiments, we inspected the presynaptic inhibition of GABA B receptors in the GIRK2 KO mice. For this purpose, CGP55845 was perfused (1 lmol/L, 10 min), and the sIPSC parameters were examined before and during drug application (Fig. 7A). CGP55845 caused an increase in the frequency of sIPSCs in the WT mice (P = 0.0431, paired two-tailed t-test; Fig. 7B, inset histogram) but not in the GIRK2 KO mice (P = 0.7461, paired two-tailed t-test; Fig. 7C, inset histogram). This effect is illustrated as a significant shift to the left of the cumulative probability plot of the interevent interval for the WT mice (P < 0.01, K-S test; Fig. 7B) but not for the GIRK2 KO mice (P = 0.5644, K-S test; Fig. 7C). CGP55845 increased the amplitude of sIPSCs in the WT mice (P = 0.0053, paired two-tailed t-test; Fig. 7D, inset histogram) but not in the GIRK2 KO mice (P = 0.1015, paired two-tailed t-test; Fig. 7E, inset histogram). This change was represented as a shift to the right in the cumulative probability plot of amplitudes for the WT mice (P < 0.01, K-S test; Fig. 7D) but not for the GIRK2 KO mice (P = 0.1285, K-S test; Fig. 7E). No effect of the drug was observed in the rise time of the events in the WT mice (P = 0.2514, paired two-tailed t-test; Fig. 7F) or in the GIRK2 KO mice (P = 0.4045, paired two-tailed t-test; Fig. 7F). However, CGP55845 increased the decay time of the sIPSCs in the WT mice (P = 0.0179, paired two-tailed t-test; Fig. 7G) but not in the GIRK2 KO mice (P = 0.2895, paired two-tailed t-test; Fig. 7G).
These results indicate that the control of GABA release exerted by presynaptic 5-HT 1A and GABA B receptors is impaired in GIRK2 KO mice.
Reduced postsynaptic GABA activity in GIRK2 KO mice
Finally, we examined whether Girk2 gene inactivation alters postsynaptic GABA A receptor-mediated neurotransmission in the DR. We inspected the whole-cell currents of DR neurons induced by two different concentrations of GABA (100 and 300 lmol/L) in the GIRK2 KO mice. In both genotypes, GABA elicited fast-onset inward currents that returned to baseline upon GABA washout (Fig. 8A). Nevertheless, a two-way ANOVA revealed that there was a significant effect of genotype on the effect induced by GABA (F 1,64 = 10.55, P = 0.0018), as the effect induced by GABA 300 lmol/L was greater in the WT mice than in the GIRK2 KO mice (P < 0.001, Bonferroni post hoc test; Fig. 8B). Moreover, the effect of GABA was concentration-dependent in the WT mice but not in the GIRK2 KO mice (F 1,64 = 15.75, P < 0.001, two-way RM ANOVA followed by Bonferroni post hoc test; Fig. 8B). These results demonstrate that Girk2 gene deletion reduces the number, activity, or time open of postsynaptic GABA A receptors.
Discussion
This study shows that GIRK2 subunits of GIRK channels contribute to the basal electrophysiological properties of DR neurons and play a pivotal role in 5-HT 1A and GABA B receptor-mediated postsynaptic currents. Moreover, the fast GABA synaptic activity and the 5-HT 1A and GABA B receptor-mediated presynaptic inhibition of GABA release is affected by inactivation of the Girk2 gene.
Genetic deletion of the GIRK2 subunit decreased the resting membrane potential, effect that was mimicked by the pharmacological blockade of GIRK channels, and increased the membrane input resistance of DR neurons. These findings demonstrate that there is a basal GIRK conductance that contributes to setting the basal membrane properties of DR neurons. In this sense, the more depolarized resting membrane potential, likely due to the relatively smaller resting K + conductance, may lead to a higher membrane input resistance in DR neurons. The GIRK2 subunit is the predominant subunit in neuronal GIRK channels and is responsible for the generation of GIRK currents in several brain regions (Liao et al. 1996;Luscher et al. 1997;Cruz et al. 2008;Torrecilla et al. 2008). Various studies have demonstrated that GIRK2 subunits primarily hyperpolarize the membrane potential of LC and hippocampal neurons (Luscher et al. 1997;Torrecilla et al. 2002), but others have provided negative results pertaining to layer 5/6 of the prelimbic cortex (Hearing et al. 2013). Although there is evidence that GIRK2 subunit expression levels in the DR are lower than those of GIRK1 and GIRK3 (Fairchild et al. 2003;Saenz del Burgo et al. 2008), our results demonstrate that, irrespective of expression levels, GIRK channels containing GIRK2 subunits control the electrophysiological properties of DR neurons. Present results also indicate that GIRK2 subunit-containing channels modulate, somehow, the duration of AP, since GIRK2 KO mice showed shorter half-width and decay times. Of note, these results were not fully replicated by the application of tertiapin-Q in WT mice; although tertiapin-Q reduced the decay time, it also increased the rise time resulting in action potentials of unaltered duration. To the best of our knowledge, although K + conductance is involved in the generation of action potentials (Hille 2001), it is unlikely that GIRK channels directly modulate the firing properties of action potentials, as it is demonstrated by our further experiments where tertiapin-Q did not mimic the changes in AP observed in GIRK2 KO mice. Therefore, the alterations in AP properties could be a consequence of the reduced GABAergic synaptic activity that the Girk2 deletion causes. In fact, modifications of the synaptic activity (e.g., blockade of GABA A receptors) were demonstrated to modulate properties of AP of layer 2/3pyramidal neurons causing a shift from afterhyperpolarization to afterdepolarization and increased the input resistance (Imbrosci and Mittmann 2013). In addition, tertiapin-Q produced an increase in the firing rate upon current injections and this effect was not seen in GIRK2 KO mice. It is likely that this altered input-output function observed after the pharmacological, but not genetic inhibition of GIRK channels is due to the complete blockade of GIRK channels and not just GIRK2 subunit-containing channels.
We showed that 5-CT-and baclofen-induced whole-cell postsynaptic currents were greatly reduced in the DR neurons of GIRK2 KO mice and completely prevented by the preapplication of tertiapin-Q in WT mice. These findings strongly suggest that the activation of GIRK2 subunitcontaining channels is necessary to mediate the postsynaptic effect of 5-HT 1A and GABA B receptor activation in DR neurons. It is known that in vitro, 5-HT 1A receptors in the mouse DR desensitize when activated by acute (15 min to 1 h) application of 5-HT 1A receptor agonists (Riad et al. 2001;Beck et al. 2004;Bouaziz et al. 2014). As a result, repeated application of 5-HT 1A and GABA B receptor agonist onto DR slices would result in currents of smaller magnitudes, precluding the construction of concentration-response curves in individual cells. Desensitization, however, could not have confounded the results obtained after the application of tertiapin-Q since there was a complete absence of 5-CT and baclofen-induced currents, indicating that GIRK2 subunit-containing channels control 5-HT 1A and GABA B receptor-mediated responses in the DR. Although not studied in the DR until now, the involvement of GIRK2 subunits in wholecell postsynaptic currents induced by the stimulation of GPCRs, such as A1 adenosine receptors, GABA B receptors, 5-HT 1A receptors, and l receptors, has been demonstrated in various brain areas, including the hippocampus, the VTA, and the LC (Luscher et al. 1997;Torrecilla et al. 2002;Cruz et al. 2008;Arora et al. 2010). In contrast, a recent pharmacological study of GIRK channels in 5-HT neurons claimed that 5-HT 1A receptor-coupled GIRK channels may not be formed by GIRK1-GIRK2 heteromers (Montalbano et al. 2015), which is the predominant form found in neurons (Liao et al. 1996). Regardless of the precise GIRK composition in the DR, our study provides direct evidence supporting the principal role of the GIRK2 subunit in mediating postsynaptic inhibition induced by GPCRs.
One key finding is that GIRK inactivation decreases the spontaneous and evoked probability of GABA release and it is supported by three distinct electrophysiological results. First, we observed that in GIRK2 KO mice the paired-pulse ratio was greater compared to WT mice, effect that is associated with decreased neurotransmitter release (Bonci and Williams 1997;Dobrunz and Stevens 1997;Melis et al. 2002). Second, the application of tertiapin-Q produced an increment in the paired-pulse ratio in WT mice, but not in GIRK 2 KO mice. Third, the frequency of the sIPSCs of DR neurons was reduced in the GIRK2KO mice, which is indicative of presynaptic regulation of release (Van der Kloot 1991). Since the reduced frequency of sIPSC demonstrates a corresponding decreased amplitude of sIPSC, it could be arguable whether the change in frequency in GIRK2 KO is due to an increased number of undetected events hidden in the noise, indicating an effect of GIRK exclusively in the postsynaptic site. Nevertheless, the increased paired-pulse ratio in GIRK2 KO mice and in WT mice after the application of tertiapin-Q supports a presynaptic role of GIRK channels in GABA release. On one hand, the reduced probability of GABA release could be indicative of a decrease in the readily releasable vesicles (Dobrunz and Stevens 1997) or alterations in the cAMP-dependent modulation of GABA release (Bonci and Williams, 1997;Cameron and Williams, 1993). On the other hand, the impaired GABA release could be consequence of an altered presynaptic inhibition. In this sense, it is not likely that GIRK inactivation directly impacts on the intracellular processes related to the regulation of synaptic release, but rather impairs the presynaptic inhibition. Importantly, if GIRK blockade were affecting exclusively the presynaptic GABA B receptor activity, GABA release should be increased. Nevertheless, GABA release is not only regulated by presynaptic GABA B receptors which reduce the release of GABA (Brenowitz et al. 1998;Waldmeier et al. 2008;Kobayashi et al. 2012), but also by presynaptic GABA A receptors, which enhance vesicle release (Trigo et al. 2008;Howell and Pugh 2016). Both GABA A and GABA B receptors are coexpressed in a wide range of terminals including afferents to the DR (Soiza-Reilly et al. 2013) and their coactivation modulates synaptic transmission (Howell and Pugh 2016). Interestingly, the GABA B receptor activation regulates the membrane expression of GABA A receptors through a BDNFdependent signaling pathway (Kuczewski et al. 2011).
These facts together with our findings suggest that there may be some kind of presynaptic GABA A -GABA B interactions in which the lack of function of GABA B receptors weakens the GABA A receptor activity so that the net effect of GIRK inactivation is a reduction in GABA release. Future studies in this direction could elucidate the exact mechanism by which GIRK channels modulate GABA release. Consistent with previous findings indicating that GABA A/B and 5-HT1 A/B agonists decrease 5-HT and GABA release in the DR (Bagdy et al. 2000), present results show that in WT mice, presynaptic 5-HT1 A and GABA B receptors control the GABAergic synaptic activity in the DR, suggesting a localization of these receptors in presynaptic GABA terminals. Additionally, the deficient 5-HT 1A and GABA B receptor-mediated presynaptic inhibition that GIRK2 KO mice exhibit points to a presynaptic modulation of GABA release by GIRK2 subunit-containing channels. Although to the best of our knowledge there are no previous studies addressing directly the functional role of 5-HT 1A receptors in the GABAergic synaptic activity, earlier electrophysiological reports demonstrated 5-HT 1A receptor-mediated responses in non 5-HT neurons of the DR (Kirby et al. 2003;Beck et al. 2004). Likewise, anatomical studies detected 5-HT 1A mRNA in GABAergic neurons (Day et al. 2004) and 5-HT 1A receptor expression in 5-HTimmunonegative cells in the DR (Kirby et al. 2003). Given that 5-HT 1B receptors have been demonstrated to control the GABA synaptic activity in the median, but not dorsal raphe (Lemos et al. 2006), our results may indicate that, besides 5-HT 1B receptors and GABA B receptors, 5-HT 1A receptors modulate the GABAergic synaptic activity in the raphe nuclei. Whether GIRK channels play a presynaptic role in neurotransmitter release undoubtedly remains a controversial question. It is thought that presynaptic inhibition of neurotransmitter release results primarily, although not necessarily entirely, due to G protein-dependent suppression of voltage gated Ca 2+ channel activity (Dolphin 2003) or due to regulation of release downstream from Ca 2+ influx (Scanziani et al. 1992;Sakaba and Neher 2003). Biochemical and morphological studies, however, have described presynaptic labeling of GIRK subunits, including GIRK2, in different brain structures (Ponce et al. 1996;Koyrakh et al. 2005;Marker et al. 2005;Ladera et al. 2008), and these findings were further supported by functional studies showing that GIRK channels control, at least in part, GABA release in the VTA and the cortex (Ladera et al. 2008;Michaeli and Yaka 2010). However, at least two studies failed to detect any presynaptic involvement of GIRK channels in neurotransmitter release in the hippocampus and periaqueductal gray (Luscher et al. 1997;Liu et al. 2012). We believe that the highly heterogeneous nature of GIRK channels regarding subunit composition depending on brain region, cell type and, likely, sub-cellular localization (for review see Luscher and Slesinger 2010) accounts for the differing results obtained in the abovementioned studies. Our data suggest that, in the DR, GIRK channels regulate presynaptic and postsynaptic processes playing an important role in presynaptic neurotransmitter release and in the control of postsynaptic GPCR-induced currents.
Two main findings in this study indicate that Girk2 gene deletion not only affects presynaptic GABA A receptor-mediated signaling but also impedes postsynaptic GABA A receptor activity. GIRK2 KO mice showed, first, reduced sIPSC amplitudes and, second, markedly reduced GABA-induced fast inward currents compared to WT mice. These observations indicate that inactivation of the Girk2 gene decreases the number, sensitivity, or time open of the activated GABA A receptor (Kirby et al. 2008), likely because the well-established regulation that postsynaptic GABA B receptors exert over GABA A receptor-mediated currents is absent in the GIRK2 KO mice (Connelly et al. 2013;Tao et al. 2013). Consistent with our observations, two studies revealed that genetic inactivation of 5-HT 1A and CB 1 receptors , which are coupled to GIRK channels, reduces the expression of certain GABA A receptor subunits as well as the whole receptor functionality (Sibille et al. 2000;Uriguen et al. 2011). Having observed similar findings in the current work, it is tempting to speculate that the reduced GABA A receptor expression and/or activity is a consequence of the lack of GIRK activity. Nonetheless, further studies are clearly required to unravel the interplay between GIRK2 and GABA A receptormediated transmission in the DR microcircuit. Extending these results beyond physiological findings, growing evidence has identified GABAergic deficiencies in the prefrontal regions of unmedicated depressed patients and in animal models of depression induced by chronic social defeat stress (Hasler et al. 2007;Venzala et al. 2013). Importantly, Challis et al. (2013) showed that social defeat stress, which results in long-lasting social avoidance and which is sensitive to the effects of antidepressants Tsankova et al. 2006), suppresses 5-HT neuronal firing through increased activity of GABA interneurons in the DR. Furthermore, decreasing GABA activity disinhibited 5-HT cells and promoted a "resilient" phenotype in mice exposed to social defeat (Challis et al. 2013). Interestingly, these findings coincide with the reduced GABAergic activity observed here and with the previously reported increased 5-HT neuronal firing and depressionresistant phenotype that GIRK2 KO mice exhibit . Moreover, from our previous study and the present work, we revealed that mice lacking GIRK2 subunits show desensitized 5-HT 1A receptors and reduced sIPSC frequency. Similarly, previous studies have reported that chronic treatment with fluoxetine, which desensitizes 5-HT 1A , and imipramine reduce GABAergic transmission in various regions of the cerebral cortex (Zhong and Yan 2004;Wabno and Hess 2013). In this regard, it is interesting that the alterations we detected in GIRK2 KO mice are opposite to those observed in socially defeated mice and mimic the effects of repeated antidepressant administrations on 5-HT and GABAergic transmissions. Therefore, approaches targeting GIRK2 subunit in the DR may be a beneficial manipulation to treat or ameliorate stress-related psychopathologies, such as anxiety and depression. This study presents a clear effect of GIRK channels on the GABAergic synaptic activity, but it is limited to electrophysiological observations in putative 5-HT neurons. In the future, in order to strengthen the present conclusions, it could be of great value to inspect the pre-or postsynaptic localization of GIRK2 subunit-containing channels in the different cells expressed in the DR and to study the contribution of GIRK channels to the physiology of this nucleus according to their cell type-specific expression and function.
In conclusion, GIRK2 subunit-containing channels play a primary role in controlling the electrophysiological properties and the 5-HT and GABAergic systems in the DR. Given the high involvement of these neurotransmission systems of the DR in the pathophysiology of affective disorders, GIRK2 subunit-containing channels may be valuable targets for studying the mechanisms underlying mood-related disorders and for developing novel therapeutic agents.
Figure 1 .
1Electrophysiological properties of the action potentials of DR neurons from WT and GIRK2 KO mice. (A) Examples of action potential (AP) waveforms of DR neurons from the WT (left) and GIRK2 KO mice (right) elicited by current injections of 50, 100, and 200 pA. Scale bars, 40 pA, 200 msec. (B) Input-output relationship curves of DR neurons from WT (n = 24 cells) and GIRK2 KO mice (n = 35 cells). (C) Examples of AP waveforms of DR neurons from the WT before (Before TPN-Q; left) and during tertiapin-Q bath application (TPN-Q; 1 lmol/L; right) elicited by current injections of 50, 100, and 150 pA. Scale bars, 40 pA, 200 msec. (D) Input-output relationship curves of DR neurons from the WT mice before and during tertiapin-Q application (n = 11 cells; *P < 0.05 and ***P < 0.001, Bonferroni post hoc test). Means AE SEM. ª 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
Figure 2 .
25-CT-induced outward currents in DR neurons from WT and GIRK2 KO mice. (A) Representative whole-cell recordings of the outward current induced by 5-CT (I-5-CT; 0.1 lmol/L) for the WT (left) and GIRK2 KO mice (right). Scale bars, 50 pA, 60 sec. Voltage steps (À60 to À130 mV) were performed before and during 5-CT bath application. Scale bars, 200 pA, 50 msec. (B) Summary bar graph showing the amplitude of the current induced by 5-CT (0.1 lmol/L) in the WT and GIRK2 KO mice (n = 12-13 cells per group; ***P < 0.001, unpaired two-tailed t-test). (C) Summary current-voltage plot of I-5-CT versus potential for WT and GIRK2 KO mice. Notice the absence of inward rectification in the GIRK2 KO mice. (D) Representative recordings of the outward current induced by 5-CT (0.1 lmol/L) in the WT mice before (Before TPN-Q) and during (TPN-Q) tertiapin-Q (1 lmol/L). Scale bars, 50 pA, 60 sec. (E) Summary bar graph showing the amplitude of the current induced by 5-CT (0.1 lmol/L) in WT before and during tertiapin (1 lmol/L) bath application (n = 9 cells; ### P < 0.0001, paired twotailed t-test). Bars represent the means AE SEM. In B and E, values from a single experiment are denoted by circles. The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
Figure 3 .
3Baclofen-induced outward currents in DR neurons from WT and GIRK2 KO mice. (A) Representative whole-cell recordings of the outward current induced by baclofen (I-Baclofen; 30 lmol/L) for the WT and GIRK2 KO mice. Scale bars, 50 pA, 60 sec. (B) Summary bar graph showing the amplitude of the current induced by baclofen (30 lmol/L) for WT and GIRK2 KO mice (n = 11-13 cells per group; ***P < 0.0001, unpaired two-tailed t-test). (C) Representative recordings of the outward current induced by baclofen (30 lmol/L) in the WT mice before (Before TPN-Q) and during (TPN-Q) tertiapin-Q (1 lmol/L). Scale bars, 50 pA, 60 sec. (D) Summary bar graph showing the amplitude of the current induced by baclofen (30 lmol/L) in WT before and during tertiapin-Q (1 lmol/L) bath application (n = 5 cells; ### P < 0.001, paired two-tailed t-test) Bars represent the means AE SEM. Values from a single experiment are denoted by circles. ª 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
Figure 4 .
4Characterization of the paired-pulse ratio of eIPSCs in DR neurons from WT and GIRK2 KO mice. (A) Examples of paired-pulse traces from recordings of eIPSCs for the WT (left) and GIRK2 KO mice (right). IPSCs from WT showed paired-pulse depression, unlike those from the GIRK2 KO mice, which showed paired-pulse facilitation. Scale bars, 400 pA, 20 msec for WT and 200 pA, 20 msec for GIRK2 KO. (B) Summary histograms showing the paired-pulse ratio (PPR) for WT and GIRK2 KO mice. (n = 17 cells per group; *P < 0.05, unpaired two-tailed t-test). (C) Cumulative distribution of the PPR for all the recorded neurons from WT and GIRK2 KO mice (n = 17 cells per group). (D) PPR is independent of the amplitude of IPSC1 for both genotypes (n = 17 cells per group). (E) Examples of paired-pulse traces from recordings of eIPSCs for the WT mice before (left) and during (right) tertiapin-Q (TPN-Q; 1 lmol/L) bath application. Scale bars, 200 pA, 20 msec. (F) Summary histograms showing the paired-pulse ratio (PPR) before and during TPN-Q for WT mice (n = 13 cells; *P < 0.01, paired two-tailed t-test) and GIRK2 KO mice (n = 17 cells). Bars represent the means AE SEM. Values from a single experiment are denoted by circles. The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
Figure 5 .Figure 6 .
56Characterization of GABAergic sIPSCs in DR neurons from WT and GIRK2 KO mice. (A) Representative current traces showing sIPSCs for the WT and GIRK2 KO mice. Scale bars, 50 pA, 100 msec. (B) Summary bar graph showing the frequency of sIPSCs in both groups (n = 31-44 cells per group; **P < 0.01, unpaired two-tailed t-test). (C) Cumulative probability histograms of interevent intervals of sIPSCs in WT (n = 3437 events from 31 cells) and GIRK2 KO mice (n = 2919 events from 44 cells). (D) Summary bar graph showing the amplitude of sIPSCs for both groups (n = 31-44 cells per group; ***P < 0.0001, two-tailed Mann-Whitney U test). (E) Cumulative probability histograms of the amplitudes of sIPSCs for the WT (n = 3517 events from 31 cells) and GIRK2 KO mice (n = 2987 events from 44 cells). Inset shows an enlarged depiction of the averaged individual events in the WT and GIRK2 KO mice. Scale bars, 10 pA, 5 msec. (F) Summary bar graph showing the rise time of sIPSCs for the WT and GIRK2 KO mice (n = 31-36 cells per group; **P < 0.01, unpaired two-tailed t-test). (G) Summary bar graph showing the decay time of sIPSCs for the WT and GIRK2 KO mice (n = 31-36 cells per group). Bars represent the means AE SEM. Values from a single experiment are denoted by circles. ª 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. Effect of the 5-HT 1A receptor antagonist WAY100635 on the sIPSCs of DR neurons from WT and GIRK2 KO mice. (A) Representative current traces before and during 1 lmol/L WAY100635 (WAY) application for the WT (left) and GIRK2 KO mice (right). Scale bars, 50 pA, 100 msec. (B-C) Cumulative probability histograms showing that WAY100635 induced a significant shift in the distribution of interevent intervals in (B) the WT (n = 843-1139 events from eight cells) but not in (C) the GIRK2 KO mice (n = 844-881 events from 10 cells). Insets display summary histograms showing that WAY100635 increased the average frequency of sIPSCs in WT but not in GIRK2 KO mice (n = 8-10 cells per group; *P < 0.05, paired two-tailed t-test). (D-E) Cumulative probability histograms showing that WAY100635 induced a significant shift in the distribution of amplitudes in (D) WT (n = 853-1141 events from eight cells) and in (E) GIRK2 KO mice (n = 845-906 events from 10 cells) . Insets display summary histograms showing that WAY100635 increased the average amplitude of sIPSCs in both genotypes (n = 8-10 cells per group; *P < 0.05, paired two-tailed t-test). (F-G) Summary bar graph showing the effect of WAY100635 application on (F) the rise time and (G) the decay time of sIPSCs for the WT and GIRK2 KO mice (n = 8-10 cells per group; *P < 0.05, paired two-tailed t-test). Bars represent the means AE SEM. Values from a single experiment are denoted by circles. 2017 | Vol. 5 | Iss. 3 | e13141 Page 10 ª 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
Figure 7 .
7Effect of the GABA B receptor antagonist CGP55845 on the sIPSCs of DR neurons from WT and GIRK2 KO mice. (A) Representative current traces before and during 1 lmol/L CGP55845 (CGP) application in the WT (left) and GIRK2 KO mice (right). Scale bars, 50 pA, 100 msec. (B-C) Cumulative probability histograms showing that CGP55845 induced a significant shift in the distribution of interevent intervals in (B) WT (n = 748-1108 events from eight cells) but not in (C) GIRK2 KO mice (n = 528-584 events from six cells). Insets display summary histograms showing that CGP55845 increased the average frequency of sIPSCs in WT but not in GIRK2 KO mice (n = 6-8 cells per group; *P < 0.05, paired two-tailed t-test). (D-E) Cumulative probability histograms showing that CGP55845 induced a significant shift in the distribution of amplitudes in (D) WT (n = 753-1115 events from eight cells) but not in (E) GIRK2 KO mice (n = 536-595 events from six cells) . Insets display summary histograms showing that CGP55845 increased the average amplitude of sIPSCs in WT but not in GIRK2 KO mice (n = 6-8 cells per group; **P < 0.01, paired two-tailed t-test).(F-G) Summary bar graph showing the effect of CGP55845 application on (F) the rise time and (G) the decay time of sIPSCs in the WT and GIRK2 KO mice (n = 6-8 cells per group; *P < 0.05, paired two-tailed t-test). Bars represent the means AE SEM. Values from a single experiment are denoted by circles. ª 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
Figure 8 .
8GABA-induced inward currents in DR neurons from WT and GIRK2 KO mice. (A) Representative whole-cell recordings of the outward currents induced by GABA (I-GABA; 300 lmol/L) for the WT and GIRK2 KO mice. Scale bars, 100 pA, 60 sec. (B) Summary bar graph showing the amplitude of the current induced by GABA (100 and 300 lmol/L) in the WT and GIRK2 KO mice (n = 15-18 cells per group; ***P < 0.001, Bonferroni post hoc test). Bars represent the means AE SEM. Values from a single experiment are denoted by circles. The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
ª 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.2017 | Vol. 5 | Iss. 3 | e13141
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Table 1 .
1General electrophysiological properties of dorsal raphe neurons of wild-type and GIRK2 KO mice. The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.WT
GIRK2 KO
Intrinsic membrane properties
Capacitance (pF)
52.29 AE 2.24 (23)
(36.50-76.12)
52.33 AE 2.37 (38)
(26.54-81.75)
Input resistance
(MΩ)
479.40 AE 31.07 (24)
(187.10-739.1)
667.00 AE 55.25* (35)
(169.70-1599.15)
Resting potential
(mV)
À57.71 AE 0.73 (56)
(À)(73-50)
À55.58 AE 1.19 # (43)
(À)(79-40)
Action potential properties
Threshold (mV)
À32.26 AE 1.94 (16)
(À)(40.67-16.01)
À35.73 AE 0.97 (35)
(À)(42.34-22.45)
Amplitude (mV)
71.48 AE 1.09 (17)
(64.62-80.75)
72.70 AE 1.06 (35)
(56.64-83.22)
Half-width (msec) 1.55 AE 0.08 (17)
(1.09-2.37)
1.33 AE 0.05* (36)
(0.85-2.68)
Rise time (msec)
0.55 AE 0.03 (14)
(0.38-0.71)
0.62 AE 0.03 (25)
(0.15-0.84)
Decay time (msec) 1.42 AE 0.08 (17)
(0.91-2.14)
1.16 AE 0.06* (36)
(0.62-1.32)
Values represent the means AE SEM of (n) cells. *P < 0.05,
unpaired two-tailed t-test; # P < 0.05, Mann-Whitney U test.
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AcknowledgmentsNone.Conflict of InterestsThe authors declare no conflict of interests.
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and emotional dysregulation were the most potent predictors that have predictive accuracy for suicidal ideation as many as 85% [7]. This neurological disease that affects the limbic system will induce emotional disturbances. Also, comorbidity has an additive adverse effect on patients' mental quality of life and is associated with an increased risk of debilitating complications, further increasing disease burden. For instance, during the MS, risk-related behaviors may expose an individual to various problematic environmental agents [8]. Despite the frequent mental disorders, comorbidities, and emotional problems in PwMS, these conditions are often underdiagnosed and undertreated [9].
Several reasons for this underdiagnosed condition have been documented. In a neurologic setting, evidence highlights the weakness of the DSM criteria application [10]. Also, the MS syndrome's heterogeneous nature and the potential for confusing specific somatic complaints of MS (e.g., fatigue) with depression symptoms may lead to falsely elevated underdiagnoses rates. Moreover, disorder-specific interventions and treatments based on primary and secondary diagnoses are not suggested to be effective with complex cases [11]. Furthermore, Disorder-specific protocols can be difficult to justify when the clinical reality is complex, and comorbidities are the norm, particularly in chronic somatic disease (e.g., MS) [12].
Cognitive Behavioral Therapy (CBT) programs have demonstrated effectiveness in promoting mental health in PwMS for treating depression [13]. Nevertheless, effective treatments for anxiety are lacking [14]. Recent findings have shown that CBT was less efficient than other interventions in the psychological treatment of PwMS [15]. Transdiagnostic and integrated therapies have emerged as recommended approaches for the treatment of several co-occurring mental health disorders, as they provide a more parsimonious [16] and more efficient strategy to working with comorbid presentations [17]. Some studies have suggested that a transdiagnostic treatment approach for PwMS can be appropriate [18].
Transdiagnostic approaches refer to identifying the etiology and maintenance mechanisms that are common in multiple disorders [19]. In emotional disorders, neuroticism has been considered a key etiology mechanism shared by all emotional disorders [20]. Other mechanisms identified have been rumination, suppression, anxiety sensitivity, and misappraisal [21], frequently reported in PwMS [22]. These mechanisms can increase or maintain persistent negative emotions and may affect physical and psychological functioning. From this perspective, transdiagnostic treatment consists of techniques that serve to target an identified set of underlying core processes [19]. Emotion regulation seems to play a critical role in the treatment of complex cases, diagnoses with a combination of psychological risk factors, or comorbidities [23]. PwMS experience higher rates of negative emotions related to different situations such as support family members, body image, pregnancy worry, uncertainty about the relationship, and sexual dysfunction [24,25].
The Unified Protocol is a CBT transdiagnostic emotion-focused skill-based therapy [26,27]. The unified protocol has been manualized to be applied to the treatment of anxiety disorders, depression, and other emotional disorders in which emotion dysregulation is a core component [28]. The protocol has been adopted in 12 to 14 sessions in a group format [29]. Numerous studies have supported the efficacy of the unified protocol in improvements on anxiety and depression symptoms, functional impairment, and well-being [27,30] chronic diseases [31], and social, job, and general performance [32].
Current study
The unified protocol is equally effective as gold-standard specific disorder protocols for individuals with comorbid emotional disorders [27]. Regarding the prevalence of emotional disorders, high comorbidities, frequent emotional problems, and the high prevalence of the riskybehaviors during the MS [8], the application of unified protocol, as an emotion-focused, skill-based intervention, could be beneficial through targeting emotion regulation mechanism, improvement emotional disorder comorbid conditions, and temperamental changes concerning neuroticism. However, there is a lack of empirical evidence on the unified protocol and MS. The purpose of the study was to examine and develop the efficacy of a group format of the unified protocol for adult PwMS with depression or anxiety symptoms. We hypothesized that at post-intervention, treatment group participants would show significant improvements in measure of depression, measures of anxiety and worry, the measure of emotion regulation, and the measure of affectivity relative to the treatment-as-usual (TAU) group. Also, we hypothesized that treatment group participants would demonstrate significantly improve on dependent variable scores compared with baseline at post-intervention.
Methods
Participants
The consort diagram is illustrated in Fig. 1 Exclusion criteria included (a) present or history diagnosis of schizophrenia, psychosis, or organic mental disorder, (b) other chronic physical illnesses, (c) pregnancy or Breast-feeding, (d) risk or history of threatening behaviors, (e) missed three consecutive sessions (f ) receiving psychological or psychiatric treatments during the study (e.g., antidepressant or anxiolytic medication), (g) moderate to high cognitive impairment or physical disabilities.
Measures
Structured Clinical Interview for DSM-IV Axis I Disorders [SCID I-IV: 34,35] was used in the current study. The diagnosis was moderate to good (Kappa coefficient higher than (0.6). Most interviewees and interviewers reported the desirable implementation of the local version of SCID-I. Kappa was higher than 0.4 for all the diagnoses except for Generalized Anxiety Disorders. The Kappa was above 0.85 in most of the diagnoses, and in half, it was above 0.9, indicating acceptable reliability
Primary outcomes measures
The hospital anxiety and depression scale [HADS : 37]. The HADS is a highly reliable screening measure for assessing anxiety and depression in PwMS. The HADS consists of 14-items, two sub-scales, 7-items for anxiety (HADS-A), and seven items for depression (HADS-D).
A suggested cutoff score of 11 demonstrated high sensitivity (90%) and specificity (92%) for the Anxiety subscale and high sensitivity (77%) and specificity (81%) for the Depression subscale [38]. This scale demonstrated acceptable reliability in this study (α = 0.90).
Difficulties in Emotion Regulation Scale [DERS : 39]. The DERS is a 36-item, self-report questionnaire that measures overall difficulties in emotion regulation. The DERS consists of six subscales: (1) no acceptance of emotional responses, (2) difficulties engaging in goal-directed behavior, (3) impulse control difficulties, (4) the lack of emotional awareness, (5) limited access, and (6) lack of emotional clarity. Respondents rated their emotional state on 1(almost never) to 5 (almost always). The total score range of 36-180. A recent study has found that a DERS total score above 97 identified a clinical sample [40]. DERS has high internal consistency (α = 0.93).
Internal consistency in the current study was acceptable (α = 0.92).
Secondary outcomes
The Positive and Negative Affect Schedule [PANAS : 41]. The PANAS is a brief self-report scale that determines positive and negative affects with two independent ten descriptors. The PANAS demonstrates the two core dimensions of mood positive affect (PA) and negative mood affect (NA). Each item is rated on a five-point scale with a range from very slightly (1) to extremely (5), indicating the extent that the participant has experienced that feeling over the past month. The PANAS has shown highly internally consistent, largely uncorrelated positive affect (0.89) to negative affect (0.95), whereas the discriminant correlations are quite low [41]. Internal consistency in the current study was acceptable (α = 0.80).
Penn State Worry Questionnaire [PSWQ : 42]. The PSWQ is a 16-item self-report measure that determines an individual's tendency to worry and intensity and excessiveness of worry on a scale of 1 (not at all typical of me) to 5 (very typical of me). The PSWQ has demonstrated reliable psychometric properties, suitable internal consistency, and test-retest reliability in the local MS population. This measure is suggested for transdiagnostic approach assessments. Internal consistency in the current study was acceptable (α = 0.83).
Procedure
The study was a single-blind, parallel randomized controlled trial comparing psychological intervention group, based on the unified protocol, with a TAU control group. The study, including all assessments and treatments, was conducted at the MS Clinic, located within the MS Centre. The study's methods and procedures were reviewed and approved by the Institutional Human Research Ethics Committee and the National Institute for Medical Research and Development, prospectively. "We used the CONSORT checklist and The TIDieR checklist when writing our report (see Additional file 1). " First, interested PwMS were notified about the study's goals, benefits, and risks, session numbers, randomization, and group allocation chance through telephone or face-to-face interviews. Only who gave verbal informed consent to participate in the study were asked to present their physician agreement or refer to the study participation. The neurologists and clinical psychologist evaluated physician agreements, referrals, medical documents for recent medication prescriptions, and examined the subjects. The eligibility criteria are related to medical conditions obtained; the participants completed the assessment protocol. Individuals who met the SCID-I-IV criteria for depression or anxiety disorders were requested to sign the consent form. All participants obtained a signed written consent form.
At last, only consented subjects who received a valid depression or anxiety diagnosis were selected for randomization. The outcomes were assessed at two timepoints: Time 1: pretreatment to pre-allocation includes baseline, Time 2: immediate after intervention: posttreatment assessment.
Sample size
The sample size for Analysis of covariance (ANCOVA) was conducted using G*Power 3.1 analysis [43]. A priori power analysis was conducted, using an alpha of 0.05, a power of 0.8, and medium to large effect size (Cohen's f = 0.35) to determine the sample size. According to G*Power, the desired total sample size was 64. Therefore, 70 participants recruited, allowing for a 10% loss of data (dropping out prior treatment, end treatment assessment).
Randomization and blinding procedures
Randomization was performed using a computer-generated sequence (www.rando mizer .org). A list of anonymous participant identification numbers was used to randomly allocate participants to treatment or control without any restrictions. An independent statistician performed new randomization after each 10-participants allocated. The concealed was disclosed at the end of the study. The independent statistician carried out the randomization and informed the patients and the monitoring board about the allocation. To masking condition assisting, participants were instructed not to disclose any information about the intervention and diagnostic status. Psychological evaluators, data collectors, assessors, and statistic investigators were blinded to the intervention, participants' group, and pervious diagnostic status.
Interventions
The unified protocol intervention
The program and sessions were structured based on the latest comprehensive published manual developed by Barlow and colleagues [26][27][28]. Group therapy consists of 12 weekly 2-h sessions. The treatment content is included topics about Motivation, psychoeducation, mindfulness, cognitive flexibility, emotion-driven behavior, and emotional avoidance, interoceptive exposure (IE), in vivo exposure, and relapse prevention. The summary of each module content and intervention schedule is demonstrated in Table 2. (See Additional file 2 for the more detailed description.)
Treatment-as-usual intervention
The control group received the TAU that consists of 12 weekly two hour sessions. The program included psychoeducation and life-long MS considerations (4 sessions), sharing experiences (4 sessions), and marital and parental counseling (4 sessions). This treatment could be considered as a psychoeducation intervention
Risk
Routine medical and psychological evaluations were accomplished before all activities (e.g., assessments, interviews, and treatment sessions). Regarding safety, the medical health care staff included two physicians and four experienced nurses also alerted in case of emergency conditions during all activities. The followup phase coincided with a viral epidemic. Therefore, in order to ensure the safety of participants, no follow-up was performed.
Statistical analysis
All analyses were conducted with SPSS software version 25 (version 25, SPSS Inc., Chicago, IL), two-tailed with an alpha level of 0.05 to determine statistical significance, following an Intention-to-Treat (ITT) analysis approach.
With the ITT approach, study participants are analyzed as members of the treatment group to which they were randomized regardless of their adherence to, or whether they received, the intended treatment. Given that the analysis was based on ITT principles, the data for all randomized 70 individuals were included in the final report.
To handle missing data, the last provided data (the last observation-carried-forward (LOCF) were considered as a next point for dropping data. An independent t-test was conducted to explore whether the participant was equivalent at baseline (Time 1). The parametric test of analysis of covariance (ANCOVA) was conducted to compare the effectiveness of the unified protocol intervention and TAU at post-treatment (Time 2). The scores on the baseline are treated as a covariate to control for pre-existing differences between the groups. Preliminary checks were conducted to ensure no violation of the assumptions of normality, linearity, homogeneity of variances, and homogeneity of regression slopes. Levene's test was used to determine normality and homogeneity of variance. Also, the homogeneity of regression slopes assumption was tested. A paired t test was conducted for all measures between (Time1-Time2) to investigate within groups' changes. The within-group effect size was calculated for both groups.
Effect sizes are reported as partial eta squared. Standardized effect size Cohen's d was calculated for pre-post treatment changes based on means and standard deviations [44]. Effect size estimates were interpreted conservatively, with 0.2, 0.5, 0.8, reflecting small, medium, and large treatment effects, respectively.
Results
Descriptive characteristics at baseline
There were no significant differences in terms of demographic features, age, duration, education, and other dependent variables at baseline (see Table 1). There was no significant difference between participants with depressive disorders and participants with anxiety disorders in the study (χ 2 = 0.91, p = 0.33). The unified protocol participants' ages ranged from 25 to 44 years, with a mean of 33.06 years (SD = 6.22). The TAU participants' ages ranged from 22 to 47 years, with a mean of 33.89 years (SD = 5.24). Seven (20%) from the unified protocol group left the experiment before Time 2. On average, participants had a very high degree of adherence and protocol well tolerated; 28(80%) of the unified protocol group completed the treatment sessions and completed all the post-treatment measures. Also, 12(37%) of the TAU group dropped out at post-treatment. Finally, 50 (71%) of all participants completed the study.
A one-way between groups ANCOVA was conducted to assess the impact of the unified protocol of reported all measures. The ANCOVA assumptions were examined before submitting the test results.
Treatment results
Depression treatment results
The ANCOVA was conducted on HADS-D. The results showed a significant main effect for group, F(1, 67) = 74.91, p < .001, η 2 p = .52, and Cohen's d = 1.9. For the group, the unified protocol significantly less HADS-D scores than TAU. The adjusted post-treatment mean for the unified protocol group (M = 8.01) was significantly less than that for the TAU group (M = 12.79).
Anxiety treatment results The ANCOVA results showed a significant main effect for group, F(1, 67) = 82.47, p < .001, η 2 p = .55, and a Cohen's d = 2.1. For groups, the unified protocol significantly less HADS-A scores than TAU. The adjusted post-treatment mean for the unified protocol group (M = 8.08) was significantly less than that for the TAU group (M = 11.68).
Emotion dysregulation treatment results The ANCOVA was conducted on DERS. The results showed a significant main effect for group, F(1, 67) = 11.04, p = .001, η 2 p = .14, and a Cohen's d = 0.42. For the group, the unified protocol significantly lower DERS scores than TAU. The adjusted post-treatment mean for the unified protocol group (M = 97.52) was significantly less than that for the TAU group (M = 112.81).
Affectivity treatment results The ANCOVA was con- A Paired t test was carried out to examine treatment effectiveness between Time 2 and Time1. These findings revealed the unified protocol had a significant effect on symptom improvement (see Table 3). Means and standard deviations were calculated at Time1 and Time 2 (see Table 4). There were no adverse events associated with this trial. A comparison test Between Time 2 and Time 1 revealed no significant differences for the TAU group.
The SCID-I -IV demonstrated 21 of 35 participants in the unified protocol group (60%) no longer met the diagnostic criteria for their principal diagnosis at the end of the study. The SCID-I-IV demonstrated no worse condition for all participants at Time2.
Discussion
MS is associated with a broad array of emotional disorders, negative symptoms, social interference, and physical disability that compromise well-being [45]. This study aimed to examine the efficacy of a group format of the unified protocol for the transdiagnostic treatment of emotional disorders and symptoms in adult PwMS. Our approach was based on the key development of the emotion regulation mechanism outlined in the unified protocol transdiagnostic treatment framework for emotional disorders. The results revealed that PwMS, who participated in the unified protocol intervention group, demonstrated significant improvements in depressive and anxiety and worry emotion regulation, and affectivity outcomes at post-treatment compared with those who participated in the TAU group. Our findings revealed significant changes in depression measure, in anxiety measure, and in worry, in emotion regulation measure, and affectivity measure in the unified protocol group at posttreatment relative to baseline.
The results are consistent with studies that indicate the unified protocol is effective in improving emotional disorders [46][47][48]. The core modules of the unified protocol are relevant to depression. Briefly, negative affect (e.g., sadness, shame, anger) and maladaptive, avoidant reactions to negative affect are targeted in the unified protocol. For example, in emotional disorders, worrying is a critical maladaptive cognitive process contributing (9.40) to the maintenance of the disorder, and worrying can be effectively targeted by promoting adaptive emotion regulation strategies [49]. PwMS focus on the disease consequences, which may be concluded to catastrophizing future, over-estimate threat, and under-estimate their abilities to cope. Present-Focused Emotion, a core module in the unified protocol, helps the patients recognize their thoughts and feelings, and concentrate on the current condition demands, making emotional experiences feel more under control and manageable. The improvement of emotion regulation can be associated with an improvement in depression and anxiety symptoms [50]. Findings revealed significant changes in DERS at posttreatment regarding with TAU group. This study develops the unified protocol benefits on difficulties emotion regulation scale have improved other clinical outcomes [51]. Also, the results provide supports for the application of emotion regulation in promoting adaptive emotion regulation among people with mental disorders [52]. In line with our investigation, numerous researches have replicated the emotional regulation implication in the treatment of depression [53], anxiety disorders [54], excessive worry, and psychological stress [21].
A large Cohen's d in the negative and positive affect was found with a higher significant effect on negative affect than positive affect. These results are the same that previous RCT, applying unified protocol in emotional disorders samples that have found changes in neuroticism/negative affect after unified protocol intervention [55]. Some studies have also found differences in extraversion/positive affect [56]. The reduction in neuroticism scores confirms the unified protocol's theory, an emotion regulation intervention targeting specifically neuroticism/negative affect [20], a psychopathology mechanism associated with the etiology of the emotional disorders [57]. These results suggest unified protocol, which typically focuses on reductions in negative affect, may also improve positive affect. Positive affect is a malleable construct and can be influenced by unified protocol. Change in positive affect can be potentially associated with improved both psychological and clinical outcomes [58]. One possible reason could be that unified protocol helps patients understand the relevant function of all range of emotions, including "positive emotions" such as happiness, joy, pride. Another possibility could be related to the group format delivery. Group therapy facilitates the normalization of MS-related experiences, and sharing with similar people reduces the stigma associated with psychological treatment.
The current study could develop the unified protocol as a transdiagnostic approach, consisting of five core modules and practical techniques for addressing different aspects of emotion regulation. Emotion dysregulation predicts quality of life, independently of disease severity and cognitive functioning [59]. Moreover, Emotional distress associated with maladaptive coping strategies is led to poor well-being rather than disease duration or severity [60]. For example, Emotional problems among mothers with MS negatively associate with the mother's ability to cope with the disease and positively associate with depressive symptoms in their healthy partners [61]. The unified protocol components, such as Psychoeducational courses, emotional skills, and stress self-management techniques can be beneficial to enhance well-being in MS [62]. Awareness of thoughts, beliefs, and interactions facilitates coping in PwMS [63]. Interoceptive exposure is another component of the unified protocol. PwMS are more sensitive to visceral sensations than healthy individuals [64]. Dysfunctions in interoceptive inference could underlie a range of pathologies such as anxiety [65]. In PwMS, bodily sensations are usually associated with high anxiety. Interoceptive exposure may be beneficial and facilitate a controlled coping behavior, and less stress react, gradually [66]. Also, individuals with better interoceptive perception demonstrate greater self-regulatory ability in experimental social interaction [67]. Meta-analytic evidence supports the use of the mindfulness-based intervention in PwMS to improve fatigue [68].
The study revealed surprising findings. There was no significant difference between the participants who received a depressive disorder diagnosis and those who received an anxiety disorder diagnosis at baseline. This finding is contrary to current insight and epidemiologic data in PwMS [69]. This finding is critical because anxiety receives far less attention in MS. DERS scores are related to both depression and anxiety levels in the MS sample [59]. According to DERS mean score at baseline, difficulties with emotion regulation is very high in PwMS.
We investigated the unified protocol's feasibility in a group format to an MS transdiagnostic sample with emotion regulation problems. According to evidence considering that emotion dysregulation is connected with less willingness to participate in psychological trials [70], we classified the sample as challenging to treat. According to the treatment retention rate in this study (71%), the treatment was well tolerated. Also, the results are in line with the data provided previous trials [29,71] confirm a significant improvement of patients treated in a group format.
Limitations
The results from this trial should be interpreted in the context of several limitations. First, the participants were generally well-educated, which can be enhanced their abilities to gain more the unified protocol and diminish the results' generalizability. A priori power analysis was conducted, using an alpha of 0.05. However, for three primary outcomes variables (HADS-A, HADS-D, and DERS) an alpha of 0.0167 should have been considered. The next limitation was that the no-follow-up made it difficult to assess prevention effects. One strength point of this study was the SCID-I-IV application at enrollment and post-treatment.
Conclusion
Overall the findings provide the support that the unified protocol could be an additional efficient as a parsimonious, transdiagnostic treatment of emotional disorders for adult PwMS. Although the results are promising, more research should be conducted to extend the findings obtained in this study. Transdiagnostic research has the potential to represent better the clinical and scientific reality of mental health problems, reflecting the complexity and comorbidity that is the norm in clinical practice. The unified protocol is equally effective as goldstandard specific disorder protocols in people without MS. Future trials are required to investigate the unified protocol effectiveness, compared with gold-standard specific disorder protocols in the PwMS. Further studies are required to assess the cost-effectiveness and efficacy of the unified protocol intervention with larger samples to promote it as part of routine care for PwMS. Economic evaluations can be simultaneously incorporated in future trials, as this has not yet been formally evaluated. There would be value in adding qualitative components into future trials to establish the unified protocol interventions' acceptability for both clinicians and clients. The findings developed the unified protocol as a mechanistically transdiagnostic approach might be applied across multiple disorders. In a unified approach, thoughts, behaviors, feelings, and body sensations are interacting dynamically, and emotional experiences influence each of them. Unified protocol Transdiagnostic intervention facilitates PwMS to learn how to respond to their unpleasant emotions more adaptively. Given the negative consequences of anxiety and depression in PwMS, interventions such as this may reduce the risk of these adverse outcomes and produce benefits for PwMS.
Fig. 1
1The participants flow chart diagram. UP unified protocol, TAU treatment as usual, ITT intent to treat, n frequency
[
36]. (Note: at the time of the study, a Persian version of the SCID for DSM-V was not yet validated. The clinical psychologists and supervisors on the study created a cross-referenced checklist and determined that patients met criteria for anxiety or depression based on both the DSM-IV and DSM-V.)
Table 1
1Demographic characteristics of the sample (N = 70) n frequency, y years, SCID-I-IV structured clinical interview for DSM-IV axis i disorders, MDD major depressive disorder, GAD generalized anxiety disorder, SAD social anxiety disorder, t independent t test, SD standard deviation, PANAS-PA positive and negative affect schedule-positive affect, PANAS-NA positive and negative affect schedule-negative affect, HADS-A the hospital anxiety and depression scale-Anxiety, HADS-D the hospital anxiety and depression scale-depression, PSWQ Penn State Worry Questionnaire, DERS difficulties in emotion regulation scale
Homogeneity of Variance was tested using Levene's test, indicating insignificance of p value (p > 0.05). The Homogeneity of Variance assumption was met for: HADS-A [F(1, 68) = 3.46, p = .07), for HADS-D [F(1, 68) = 3.61, p = .06] for DERS F(1, 68) = 1.89, p = .17, for PANAS-PA [F (1, 68) = 1.51, p = .38], for PANAS-NA [F (1, 68) = 2.80, p = .10], and for PSWQ F(1,68) = 1.14, p = .28]. Also, the homogeneity of regression slopes assumption was met for: HADS-A [ F(1, 66) = 1.02, p = .32), for HADS-D [F(1, 66) = 1.56, p = .14] for DERS F(1, 66) = 1.895, p = .17, for PANAS-PA [F (1, 66) = 0.04, p = .84], for PANAS-NA [F (1, 66) = .065, p = .80], and for PSWQ [F(1, 66) = 2.10, p = .15]. There was no significant interaction between the covariates and the intervention.
ducted on PANAS-PA and PANAS-NA. The PANAS-NA. The results showed a significant main effect for group, F(1, 67) = 62.19, p < .001, η 2 p = .48, and a Cohen's d = 1.89. The adjusted post-treatment mean for the unified protocol group (M = 18.98) was significantly less than that for the TAU group (M = 27.50). The PANAS-PA results showed a significant main effect for group, F(1, 67) = 47.99 p < .001, η 2 p = .42, and a Cohen's d = 1.51. The adjusted post-treatment mean for the unified protocol group (M = 30.68.) was significantly higher than that for the TAU group (M = 24.83). Worry treatment results The ANCOVA was conducted on PSWQ. The results showed a significant main effect for group, F(1, 67) = 34.78, p < .001, η 2 p = .34, and a Cohen's d = 1.2. The adjusted post-treatment mean for the unified protocol group (M = 34.24) was significantly lower than that for the TAU group (M = 46.26).
. Participant recruitment efforts included notifying MS clinics and MS associations through the use of brochures and posters. A total of 122 people were assessed to participate in the trial. Of these, 70 (44 females) met all eligibility criteria. Participants' ages ranged from 22 to 47 years. The mean age of the participants was 35.30 (SD = 3.01). The participants were generally well-educated. The baseline assessment is demonstrated in Table 1. Inclusion criteria included (a) fluent in Persian, (b) at least 18 years of age, (c) a valid diagnosis of MS, (d) obtained a consort, (e) received a diagnosis of depression or anxiety disorders based on DSM-IV [33] [Diagnostic and Statistical Manual of Mental Disorders,fourth edition; American Psychiatric Association, 2000],
(f ) medical agreement or valid referral document for
participation.
Table 2
2Content and the number of sessions for moduleThe Modules of three, four, five, six, and seven are Core modules a Week 3 and week 13 can be deleted based on the 12 session programModule
Schedule
Content and the number of sessions for module
One
Week 1
Setting goals and maintaining motivation (1 session)
Two
Week 2
Understanding emotions (1sessions)
Three
Week 3and 4 a
Mindful emotion awareness (2 sessions)
Four
Week 5 and 6
Cognitive flexibility (2 sessions)
Five
Week 7
Countering emotional behaviors (1sessions)
Six
Week 8
Understanding and confronting physical sensations (1session)
Seven
Weeks 9 to 13 a
Emotion exposures (5 sessions)
Eight
Week 14
Recognizing accomplishments and looking to the future (1 session)
Table 3
3Paired t test and within group effect size at postinterventionTime2-Time1 post-treatment to baseline, CI confidence interval of the differenceItem
Treatment
as usual
group
Unified protocol group
t(34)
p
t(34)
p
Cohens'd [95%CI]
Anxiety
1.95 .062 10.54 p < .001 − 2.78 [− 3.67,
− 2.01]
Depression
− .46 .643
7.83 p < .001 − 2.01 [− 2.78,
− 1.35]
Emotion difficul-
ties
− 2.01 .052
3.07 p < .01 − 0.20 [− 0.66,
− 0.14]
Positive affect
1.98 .055 − 7.01 p < .001 1.44 [0.86, 2.08]
Negative affect
− .98 .327
8.26 p < .001 − 1.95 [− 2.65,
− 1.31]
Worry
.65 .512
6.89 p < .001 − 1.45 [− 2.02,
− 0.92]
Table 4
4Mean (SD) at pre-treatment at pre-treatment
and post-treatment
Time1: pre-treatment, Time2: post-treatment to
Item
Treatment as usual group Unified protocol group
Time1
Time2
Time1
Time2
Anxiety
12.40 (1.37) 11.69 (1.65) 12.57 (1.40)
8.09 (1.82)
Depression
12.60 (1.65) 12.80 (2.00) 12.88 (1.80)
7.9 (2.79)
Emotion dif-
ficulties
108.74 (8.46) 114.3 (16.63) 110.1 (12.17) 106.5 (20.42)
Positive affect 26.43 (3.98) 25.00 (3.40) 25.20 (3.36) 30.51 (3.79)
Negative
affect
26.69 (3.03) 27.51 (3.77) 27.43 (3.27) 18.97 (5.04)
Worry
47.00 (8.42) 46.09 (8.60) 48.00 (8.86) 34.43
AcknowledgementsNot applicable.Supplementary informationSupplementary information accompanies this paper at https ://doi. org/10.1186/s4035 9-020-00480 -8. Authors' contributions NN and MS designed the study protocol with important contributions from EG Translated the original unified protocol manuals. NN and DM and all their collaborators are in charge of recruiting study participants. All authors contributed in drafted the manuscript. All authors participated in the review and revision of the manuscript and have approved the final manuscript to be published. EG and DM were the study methodologist. EG also contributed to the revision. All authors read and approved the final manuscript.FundingThe authors received no financial support for the research, authorship, and/or publication of this article.Availability of data and materialsThe data that support the findings of this study are available on request from the corresponding author.Ethics approval and consent to participateThe study has been performed in accordance with the Declaration of Helsinki and has been approved and registered by the ethical and research committees from the following collaborating centers. The study, including all assessments and procedures for the study, was reviewed by the National Institute for Medical Research and Development (NIMAD); prospectively (number: IRCT20190711044173N1; Registered at 31octobe2019, https ://en.irct.ir/user/ trial /40779 /view). All participants provided a signed written consent.Consent for publicationNot applicable.Competing interestsThe authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.Received: 20 April 2020 Accepted: 22 October 2020
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| Abstract The diagnoses of generalized anxiety disorder (GAD) according to DSM-III and according to revised criteria (requiring 6 months' duration and 6 symptoms) were determined by the use of the National Institute of Mental Health Diagnostic Interview Schedule in a probability sample of 357 women. The DSM-III GAD lifetime rate of 45% was reduced by a factor of five when the revised definition was applied. The reduction was due chiefly to the longer duration criterion. Requiring a higher number of symptoms did not raise the threshold for the diagnosis, since 74% of persons with a period of 1 month or more of generalized anxiety reported six symptoms. Although chronicity was associated with more pervasive symptomatology, the excess in symptoms appears to be due to the very high prevalence of major depression (73%) among the newly defined (i.e., chronic) GAD positives. | Abstract Diminished levels of mindfulness (awareness and acceptance/nonjudgment) and difficulties in emotion regulation have both been proposed to play a role in symptoms of generalized anxiety disorder (GAD); the current studies investigated these relationships in nonclinical and clinical samples. In the first study, among a sample of 395 individuals at an urban commuter campus, self-reports of both emotion regulation difficulties and aspects of mindfulness accounted for unique variance in GAD symptom severity, above and beyond variance shared with depressive and anxious symptoms, as well as variance shared with one another. In the second study, individuals with GAD ( n = 16) reported significantly lower levels of mindfulness and significantly higher levels of difficulties in emotion regulation than individuals in a nonanxious control group ( n = 16). Results are discussed in terms of directions for future research and potential implications for treatment development. |
Background
Generalized Anxiety Disorder (GAD) encompasses a variety of symptoms including excessive worrying, restlessness, irritability, difficulties in concentration, and constantly feeling on edge. Among the anxiety disorders, GAD is perhaps the least well researched or understood in part because of multiple revisions of the diagnostic criteria, consideration of the diagnosis as a "wastebasket" category when other anxiety diagnoses could not made, and because worrying was assumed a part of everyday life and associated with minimal impairment. However, GAD is now known now to be a significant disorder with high prevalence and significant impairment and disability [1,2]. Worldwide an estimated 3.7% of individuals will have GAD in their lifetime [1]. The role and quality of life impairments of GAD are comparable in magnitude to those of major depression and greater than those associated with substance abuse disorders [3].
Randomized controlled trials (RCTs) have identified effective pharmacological and psychosocial treatments [4][5][6][7]. However, results from RCTs do not necessarily translate into real-world settings and are largely restricted to high-income countries (HICs) with little global evaluation of the effects of treatment [8][9][10]. Moreover, RCTs have focused on symptom reduction as the critical and sometimes the sole outcome. Yet, symptom reduction does not necessarily equate with functional improvement, quality of life, or feelings on the part of the patient that they have been helped [11,12].
Perceived helpfulness of treatment is a key construct that may capture whether patients achieve personally meaningful goals through treatment. Helpfulness is important in its own right, but also has a critical role in treatment in that perceived helpfulness relates directly to treatment adherence as well as to critical processes that span diverse forms psychotherapy (e.g., the therapeutic alliance, critical incidents during treatment, openness of the therapist) [13][14][15][16]. Helpfulness as an outcome of treatment has received little attention in GAD trials [17]. The extent to which helpfulness is achieved with treatment and whether this is achieved initially as the patient traverses different treatments remain to be evaluated. Such research might help identify unmet patient needs that can be targeted through policy and service responses [14,18,19]. Patient-centered research on perceived GAD treatment helpfulness may also inform treatment guidelines for GAD, which are currently based on a relatively small number of RCTs.
The likelihood of a help-seeking individual ever obtaining helpful treatment is a joint function of two treatment pathways: 1) the probability that a given treatment provider will be helpful, and 2) the probability that a patient will persist in help-seeking after prior unhelpful treatment encounters. Research on these processes for depression and posttraumatic stress disorder found that the majority of patients who persisted after previous unhelpful treatments eventually obtained helpful treatments, but that only a minority persisted in help-seeking after more than a few unsuccessful treatment encounters [20,21]. It is unknown whether these patterns also are true for GAD. Decomposing treatment pathways for GAD would answer this question and might also reveal modifiable predictors of GAD treatment helpfulness and persistence that could be the focus of treatment quality improvement initiatives.
The present study evaluated the helpfulness of treatment encounters and predictors and pathways leading to helpfulness in national community epidemiological samples that included respondents with a history of GAD who sought treatment for their GAD. The data come from the World Mental Health (WMH) Survey Initiative [22]. This is a coordinated series of general population surveys under the auspices of the World Health Organization. Data were collected in 23 countries of varying income levels. This data set provides a unique opportunity to evaluate helpfulness internationally and to investigate predictors and pathways of perceived treatment response in countries varying in income levels.
Methods
Samples
The World Health Organization's (WHO) World Mental Health (WMH) surveys are a coordinated set of community epidemiological surveys administered to probability samples of the non-institutionalized household population in countries throughout the world (https://www.hcp.med.harvard. edu/wmh/) [23]. Data The interview schedule was developed in English and translated into other languages using a standardized WHO translation, back-translation, and harmonization protocol [24]. Interviews were administered face-to-face in respondents' homes after obtaining informed consent using procedures approved by local Institutional Review Boards. To reduce respondent burden, interviews were administered in two parts. Part I was administered to all respondents and assessed core DSM-IV mental disorders. Part II assessed additional disorders and correlates and was administered to all respondents who met lifetime criteria for any Part I disorder and a probability subsample of other Part I respondents [25].
Measures
Generalized anxiety disorder (GAD)
Lifetime history of GAD was assessed with the fully structured WHO Composite International Diagnostic Interview (CIDI) Version 3.0 [23]. In an evaluation carried out in conjunction with the US WMH survey [26], GAD diagnoses based on the CIDI had good concordance with diagnoses based on blinded clinical reassessments with the Structured Clinical Interview for DSM-IV (SCID) [27]. A clinical reappraisal study in other WMH surveys, although not evaluating GAD in isolation, found good concordance between diagnoses based on the CIDI and SCID for any 12-month anxiety disorder including GAD [28]. Consistent with previous studies that modified the CIDI GAD algorithm [1,26,29], we generated DSM-5 GAD diagnoses by removing the DSM-IV hierarchical exclusion of a GAD diagnosis when symptoms occur exclusively during a mood disorder [30]. Age of onset (AOO) of GAD was assessed using probing methods demonstrated to improve dating accuracy [31].
Perceived helpfulness of treatment for GAD
Respondents who met lifetime criteria for GAD were asked whether they had ever "talk [ed] to a medical doctor or other professional about their worry or anxiety" and, if so, how old they were the first time they did so. "Other professionals" were defined broadly to include "psychologists, counselors, spiritual advisors, herbalists, acupuncturists, and other healing professionals." Respondents who had ever spoken to a professional about their GAD were asked whether they ever received treatment they "considered helpful or effective" (emphasis in original). If so, they were asked how many professionals they ever talked to about their worry or anxiety "up to and including the first time [they] ever got helpful treatment". Respondents who said they never received helpful treatment were asked how many professionals they ever talked to about their worry or anxiety.
Predictors of obtaining helpful treatment for GAD
In addition to age of onset of GAD (continuous), we considered 5 classes of predictors of helpful treatment: Socio-demographic characteristics included sex, marital status (currently married, never married, or previously married) at the time of first treatment, and education (in quartiles defined by within-country distributions) at the time of first treatment. Lifetime comorbid conditions included other lifetime anxiety disorders (including panic disorder or agoraphobia with/ without panic disorder, post-traumatic stress disorder, specific phobia, and social phobia), major depressive disorder, broadly defined bipolar spectrum disorder [32], alcohol and/ or drug abuse, and alcohol and/ or drug dependence but not abuse. Comorbid conditions were restricted to disorders with an age-of-onset prior to the age at which the respondent first sought treatment for GAD. All comorbid conditions were assessed with the CIDI. Treatment type was defined as a cross-classification of (i) whether the respondent reported receiving medication, psychotherapy, or both, as of the age of first GAD treatment; and (ii) the types of treatment providers seen as of that age. Types of providers included mental health specialists (psychiatrist, psychiatric nurse, psychologist, psychiatric social worker, mental health counselor), primary care providers, human services providers (social worker or counselor in a social services agency, spiritual advisor), and complementary-alternative medicine (other type of healer or self-help group). Treatment timing included a continuous variable for length of delay in years between age of onset of GAD and age of initially seeking treatment, and a dichotomous measure for whether the respondent's first attempt to seek treatment occurred before or after the year 2000. The year 2000 was the typical midpoint between the start of observations and survey field dates. Childhood adversities included retrospective reports of significant stressors experienced during childhood, including family dysfunction (physical or sexual abuse, neglect, parental mental disorder, parental substance use disorder, parental criminal behavior, and family violence) and other adversities (parental death, parental divorce, other loss of a parent, physical illness, and economic adversity).
Analysis methods
The sample was limited to respondents with a history of DSM-5 GAD treatment who sought treatment for the disorder at some time in their life. Cases were limited to those who first sought GAD treatment in 1990 or later to reduce the potential effects of recall bias. To investigate the two pathways of helpful treatment separately, we used discrete-event survival analysis to calculate the conditional and cumulative probabilities of: (i) obtaining helpful treatment after seeing between 1 and 10 professionals; and (ii) persisting in help-seeking after obtaining prior unhelpful treatment [33]. We followed respondents up through 10 professionals in the total sample and in HICs because this was the last number where at least n = 30 respondents received treatment. However, in low/ middle-income countries (LMICs), we followed respondents only up through 3 professionals seen because this was the last number where at least n = 30 respondents received treatment.
We then carried out parallel survival analyses of the predictors of these two decomposed, encounter-level outcomes using standard discrete-time methods and a logistic link function [34], followed by a person-level model of overall probability of ever obtaining helpful treatment regardless of number of professionals seen (composite outcome). This allowed us to investigate predictors of obtaining helpful treatment at the person level and to investigate the extent to which these predictors were important because they predicted differential helpfulness at the encounter level, differential probability of persisting after earlier unhelpful treatments, or both.
We also investigated possible interactions of each significant person-level predictor with country income group and historical time (beginning treatment in 1990-1999 vs. 2000+) in an effort to examine the generalizability of the findings. Because the WMH sample design used weighting and clustering in all countries, all statistical analyses were carried out using the Taylor series linearization method [35], a design-based method implemented in the SAS 9.4 program [36]. Logistic regression coefficients and +/− 2 of their design-based standard errors were exponentiated to create odds-ratios (ORs) and 95% confidence intervals (CIs) (with odds ratios less than 1 indicating lower likelihood, and odds ratios greater than 1 indicating greater likelihood, of the relevant association). Significance of sets of coefficients was evaluated with Wald χ 2 tests based on designcorrected coefficient variance-covariance matrices. Statistical significance was evaluated using two-sided, design-based .05 level tests.
Results
GAD prevalence, treatment, and perceived helpfulness of treatment
Lifetime prevalence (SE) of GAD was 2.8% (0.1) in LMICs, 5.3% (0.1) in HICs, and 4.5% (0.1) across all WMH surveys (Table 1). Among respondents with lifetime GAD, approximately one-third reported ever obtaining GAD treatment (34.6% [0.8]) and 70.0% (1.4) of those who obtained GAD treatment perceived the treatment to be helpful. Respondents with GAD in LMICs were significantly less likely than those in HICs to obtain GAD treatment (19.2% vs. 38.4%; χ 2 1 = 63.6, p < 0.001), but probability of treatment being perceived as helpful did not differ significantly by country income level (62.8% vs. 70.9%; χ 2 1 = 2.7, p = 0.099).
Helpful GAD treatment across professionals seen
Across all countries, 26.7% (1.0) of respondents who received treatment said they were helped by the first professional they saw ( Table 2, Part I). The conditional probability of obtaining helpful treatment from a second professional seen after an initial unhelpful treatment was 36.6%. Conditional probabilities of obtaining helpful treatment generally declined after subsequent professionals seen but projected cumulative probabilities of obtaining helpful treatment rose from 26.7% after the first professional seen to 53.5% among respondents who persisted in seeing a second professional and to 96.9% among those who persisted in seeing up to 10 professionals after prior unhelpful treatments ( Table 2, Part II). These cumulative probabilities were broadly similar for LMICs and HICs up through three professionals seen (66.9% vs. 68.9%), after which the number of remaining respondents in LMICs became too small for analysis (eTable 2).
Persistence with help-seeking for GAD following treatment failure Across all countries, 77.3% (1.1) of respondents persisted in seeing a second professional after initial unhelpful GAD treatment (Table 3). This proportion was higher in HICs (79.6% [1.2]) than LMICs (55.8% [3.5]). Conditional probabilities of help-seeking persistence remained quite high (81.9-100.0%) in the total sample up through 10 professionals seen. Unlike the situation with cumulative probabilities of obtaining helpful treatment, which, by definition, either remains the same or rises as the number of professionals seen increases, the cumulative probability of help-seeking persistence either remains the same or decreases as the number of professionals seen increases. In the total sample, the cumulative probability of persistence through 10 professionals was 29.7%. We were able to compare respondents in LMICs to those in high income countries through four professionals seen, where the cumulative probability of persistence was lower in LMICs (43.2% [5.9]) than in high income countries (57.5% [2.5]) (eTable 3).
Predictors of obtaining helpful treatment for GAD
We examined predictors of each respondent ever obtaining helpful GAD treatment regardless of number of professionals seen (Model 1; Table 4), then examined predictors separately for the two pathways to helpful treatment: obtaining helpful treatment from a given professional (Model 2; Table 4) and persisting in helpseeking after prior unhelpful treatment (Model 3; Table 4). We focus on the significant predictors at the personlevel (Model 1; Table 4) and examine how the results in the decomposed models help explain these person-level associations. Due to high comorbidity between disorders and the potential for multicollinearity, we evaluated associations with comorbid disorders in separate univariate Other childhood adversities include: parental death, parental divorce, other loss of a parent, physical illness, and economic adversity and then multivariate models. Only comorbid disorders that significantly predicted obtaining helpful treatment in the multivariate models were included in Models 1-3 as individual predictors (eTable 4). At the person-level, significant predictors of obtaining helpful treatment were treatment type (χ 2 4 = 12.3, p = 0.015), comorbid panic/agoraphobia (χ 2 1 = 8.9, p = 0.003), and childhood adversities (χ 2 2 = 9.7, p = 0.008). The association with treatment type was because respondents who received treatment from a mental health specialist in combination with medication had significantly increased relative-odds of obtaining helpful treatment than those who received treatment in the human services sector (the reference category; OR:1.46; 95% CI: 1.05, 2.02). Decomposition showed that this person-level association of treatment from a mental health specialist in combination with the outcome was due to lower relative-odds of encounter-level helpfulness (OR: 0.76; 95% CI: 0.62, 0.93), but higher relative-odds of treatment persistence (OR: 2.00; 95% CI: 1.50, 2.67). Comorbid panic/agoraphobia was associated at the person-level with having significantly increased relative-odds of obtaining helpful treatment (OR: 1.79; 95% CI: 1.22, 2.62) due to increased relative-odds of treatment persistence (OR: 2.12; 95% CI: 1.53, 2.94).
Childhood adversities were also important predictors of treatment helpfulness, but unexpectedly, the pattern of associations was different for the two classes of adversities. A history of family dysfunction was significantly associated with reduced relative-odds of obtaining helpful treatment at the person-level (OR: 0.75; 95% CI: 0.58, 0.96), whereas a history of other childhood adversities was significantly associated with increased relative-odds of obtaining helpful treatment (OR: 1.47; 95% CI: 1.09, 1.99). Decomposition showed that the person-level association of family dysfunction with the outcome was due to significantly reduced relative-odds of treatment persistence (OR: 0.73; 95% CI: 0.57, 0.93), whereas the person-level association other childhood adversities with the outcome was due to significantly increased relativeodds of treatment persistence (OR: 1.51; 95% CI: 1.10, 2.07). It is noteworthy that the zero-Pearson correlation between the two CA measures is too low (r = 0.23) to create an opposite-sign pattern as a methodological artifact. Consistent with this observation, the same opposite-sign pattern was also observed in models where only one of the two CA measures was included.
Although the omnibus χ 2 tests for treatment timing and treatment delay were not significant, there were significantly increased relative-odds of both predictors with significantly decreased relative-odds of with persistence in help-seeking after an initial unhelpful treatment, were found for both beginning treatment in more recent years (2000 or later) and longer treatment delays in obtaining helpful treatment from a given professional, resulting in nonsignificant associations at the person-level.
We found significant interactions of treatment type and childhood adversities with country income level (eTable 5). These interactions were due to the predictors being more strongly associated with person-level treatment helpfulness in LMICs than HICs (eTables 6 and 7), but the significant associations were based on such small numbers of cases that substantive interpretation is hazardous. Significant interactions were also found between treatment type and historical time (eTable 8). These were due to mental health specialist and psychotherapy treatment and general medical treatment both having increased relative-odds of person-level treatment helpfulness only during the years 1990-1999 and receiving treatment from 2+ types of professionals having increased relative-odds of person-level treatment helpfulness only during the years 2000+ (eTables 9 and 10). Again, though, these interactions were based on relatively small numbers of cases and should be interpreted with caution.
Discussion
The main findings of the study are as follows. First, only about one-third of people with GAD reported ever obtaining treatment, with a lower proportion in LMICs than HICs (19.2% vs. 38.4%). Second, 70% of those who received treatment perceived the treatment to be helpful. This did not vary by country income level. Third, persistence in help-seeking was required to obtain helpful treatment, as only about one-fourth of patients were helped by the first professional they saw and about half by the first two professionals. Projections from our survival models suggest that up to 10 professionals might be needed to have a 90% probability of being helped, but that only 29.7% of patients would persist that long in the face of repeated unhelpful treatment encounters. Fourth, only relatively modest predictors were found of obtaining helpful treatment at the person-level, most of which were important because they predicted persistence rather than encounter-level treatment helpfulness.
It is encouraging that the large majority (70.0%) of respondents with lifetime DSM-5 GAD who sought treatment eventually obtained treatment they considered helpful. This means that the majority of patients persisted up to 3-4 professions in the face of initial unhelpful treatment. This is a lower persistence rate than found in a parallel analysis of specific phobia [37], but a higher persistence rate than found in parallel analyses of patients with major depression [20] and PTSD [21], possibly because depressive and PTSD symptoms are more likely than anxiety symptoms to lead to discouragement in help-seeking. Even so, we estimated than only 22.7% of GAD patients would persist in help-seeking to a point where they had near certainty of receiving helpful treatment.
Our data on the predictors of helpfulness are useful in beginning to delineate pathways. Patients who received treatment from a mental health specialist in combination with medication had significantly increased relative-odds of obtaining helpful treatment at the person-level than those who received treatment in the human services sector. This was due to lower relative-odds of encounter-level helpfulness, but higher relative-odds of treatment persistence. Patients who receive medication in addition to seeing a mental health specialist may have been more severe than other patients, resulting in lower relative-odds of encounter-level helpfulness due to the severity of their illness, but also more motivation to persist in help-seeking because of that high severity. Likewise, panic/agoraphobia was also associated with having significantly increased relative-odds of obtaining helpful treatment at the person-level due to increased relative-odds of treatment persistence. These individuals may have more chronic and impairing courses of illness [38] which may motivate them to persist in help-seeking.
The relationship between childhood adversity and treatment helpfulness was less straightforward. Family dysfunction was associated with lower relative-odds of obtaining helpful treatment due to lower relative-odds of treatment persistence. In contrast, other childhood adversities were associated with greater relative-odds of obtaining helpful treatment due to increased relativeodds of treatment persistence. One possible explanation for this difference is that the family dysfunction category included violent and traumatic forms of adversity, whereas the other childhood adversities category did not [39]. If this finding is replicated in other studies, future research should focus on why traumatic childhood events are associated with lower persistence in helpseeking, which could inform treatment guidelines.
Important limitations of this study should be noted. First, there was limited information about the precise nature of the interventions that respondents received and no information about sequencing of treatments across types of providers. Moreover, the treatments were not randomized nor evaluated in relation to quality of delivery (treatment integrity) or compliance on the part of the patient (adherence). Consequently, the relation of critical dimensions of treatment to helpfulness could not be discerned. Second, the sample was limited to respondents with onset of GAD treatment after 1990. Recall may have been biased and influenced evaluations of the treatments and helpfulness [40]. It is unclear whether these limitations would lead to upward or downward bias in estimates of treatment effectiveness at the encounter level or patient level. Despite these limitations, to our knowledge this is the first study of perceived helpfulness of treatment of GAD. A strength of the study is including large sample representing multiple countries and with the ability to evaluate commonalities and differences among low and middle income and highincome countries.
RCTs are clearly required to determine the efficacy and effectiveness of GAD treatments [4][5][6][7]. Although our data do not fill this need, they are important because they address issues that RCTs cannot. Specifically, RCTs typically focus on short-term effects (e.g., 3 months), assess mainly symptomatic changes, and exclude many people who might have more complicated disorders, such as those with psychiatric comorbidities but who would benefit from treatment [8]. Our study, in comparison, looked at a broad and representative sample without these exclusionary criteria and included information on how patients view their treatment. We would encourage the assessment of treatment helpfulness in clinical trials because it is distinguishable from symptomatic change. One can readily conceive of patients showing similar or identical changes on standardized symptom measures but in fact profiting in different degrees from treatment in their everyday lives and hence in their views of how much they have been helped [41].
Our findings suggest that treatment guidelines should not only encourage evidence-based interventions, but also should emphasize the value of treatment persistence. Our data do not allow us to study new treatments from the same provider. The persistence we examined was across providers. It should be noted, though, that evidence is clear in showing that patients can also be helped by new treatments from the same provider [42]. Further work is needed to expand GAD care to address treatment motivations and expectations and to determine the extent to which interventions to improve GAD treatment quality and persistence can improve outcomes.
Abbreviations CIDI: Composite International diagnostic interview; GAD: Generalized anxiety disorder; RCT: Randomized control trial; WHO: World health organization; WMH: World mental health
Supplementary Information
The online version contains supplementary material available at https://doi. org/10.1186/s12888-021-03363-3.
Additional file 1: Table 1. WMH sample characteristics by World Bank income categories a . Table 2. Conditional and cumulative probabilities of obtaining helpful treatment for generalized anxiety disorder after each professional seen, among respondents with lifetime DSM-5 generalized anxiety disorder who obtained treatment in low/middle-income and high-income countries. Table 3. Conditional and cumulative probabilities of persistence in help-seeking after previous unhelpful treatment, among respondents with lifetime DSM-5 generalized anxiety disorder who obtained treatment in low/middle-income and high-income countries. Table 4. Predictors of obtaining helpful treatment (person-level), among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment. Table 5. Interactions between main effects and country income group to predict obtaining helpful treatment (person-level composite outcome) and the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment. Table 6. (Low/ middle-income countries): Predictors of obtaining helpful treatment (person-level composite outcome) and of the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment. Table 7. (High-income countries): Predictors of obtaining helpful treatment (person-level composite outcome) and of the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment. Table 8. Interactions between main effects and historical time to predict obtaining helpfulness of treatment (person-level composite outcome) and the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment. Table 9. (Started GAD treatment in 2000 or later): Predictors of obtaining helpful treatment (person-level composite outcome) and of the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment. Table 10. (Started GAD treatment 1990 to 1999): Predictors of obtaining helpful treatment (person-level composite outcome) and of the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment.
Abbreviations. GAD generalized anxiety disorder; SE, standard error *Significant at the .05 level, two-sided testa Cases are based on three conditions: (i) Respondents obtained GAD treatment; (ii) Year of first GAD treatment ≥1990; and (iii) Age at onset of GAD ≤ Year of first GAD treatment b Cases are based on four conditions: (i) Respondents obtained GAD treatment; (ii) Year of first GAD treatment ≥1990; and (iii) Age at onset of GAD ≤ Year of first GAD treatment; and (iv) Respondents obtained helpful treatment
for the current report came from 26 WMH surveys carried out in 23 countries -9 in countries classified by the World Bank as low/middle-income (Brazil, Bulgaria [separate surveys carried out in 2002 and 2016], Colombia, Colombia [Medellin], Iraq, Lebanon, Mexico, and Peru) and 17 in countries classified as HICs (Argentina, Australia, Belgium, France, Germany, Israel, Italy, Japan, the Kingdom of Saudi Arabia, the Netherlands, New Zealand, Northern Ireland, Poland, Portugal, Spain, Spain [Murcia], and the United States). Response rates ranged from 45.9% (France) to 97.2% (Colombia [Medellin]) and averaged 67.4% across surveys (see eTable 1 for detailed survey characteristics).
Table 1
1Lifetime prevalence of DSM-5 generalized anxiety disorder (GAD), proportion of respondents with lifetime GAD who obtained treatment, and proportion of treated respondents who perceived treatment as helpfulTotal sampleRespondents with lifetime GAD Respondents who obtained treatment for GAD Prevalence of lifetime GAD Proportion who obtained treatment a Proportion who perceived treatment as helpful b%
(SE)
(n)
%
(SE)
(n)
%
(SE)
(n)
I. Low/middle-income countries
Sao Paulo, Brazil
5.1
(0.4)
(5037)
23.6
(3.5)
(280)
71.4
(7.4)
(63)
Bulgaria
2.2
(0.2)
(6826)
16.8
(3.2)
(157)
69.4
(10.0)
(27)
Colombia
1.9
(0.3)
(4426)
15.8
(4.6)
(84)
45.0
(17.4)
(15)
Medellin, Colombia 3.8
(0.5)
(3261)
17.9
(3.4)
(127)
73.7
(9.8)
(31)
Iraq
5.0
(0.6)
(4332)
22.2
(5.5)
(220)
52.5
(13.8)
(33)
Lebanon
2.3
(0.3)
(2857)
12.4
(4.7)
(71)
38.1
(19.1)
(9)
Mexico
1.1
(0.2)
(5782)
8.5
(3.8)
(78)
28.4
(17.6)
(8)
Peru
1.0
(0.1)
(3930)
23.0
(8.3)
(40)
82.1
(8.5)
(10)
All
2.8
(0.1)
(36,451)
19.2
(1.8)
(1057)
62.8
(4.9)
(196)
χ 2
7
242.3*
8.4
11.2
II. High-income countries
Argentina
5.2
(0.6)
(3927)
34.7
(6.0)
(224)
85.1
(6.0)
(70)
Australia
8.0
(0.4)
(8463)
49.0
(2.5)
(713)
76.7
(3.0)
(326)
Belgium
3.2
(0.8)
(1043)
35.6
(12.5)
(62)
33.9
(18.5)
(20)
France
6.0
(0.7)
(1436)
33.2
(4.4)
(159)
71.1
(7.7)
(62)
Germany
1.7
(0.4)
(1323)
34.2
(8.7)
(48)
80.5
(13.3)
(19)
Israel
4.4
(0.3)
(4859)
36.9
(3.4)
(216)
44.6
(5.9)
(76)
Italy
1.9
(0.3)
(1779)
24.3
(4.8)
(78)
89.1
(6.2)
(25)
Japan
2.6
(0.3)
(4129)
30.9
(4.8)
(105)
67.5
(10.2)
(30)
Netherlands
3.6
(0.4)
(1094)
46.4
(6.3)
(95)
88.3
(5.3)
(45)
New Zealand
7.9
(0.3)
(12,790)
41.2
(1.9)
(1084)
68.0
(2.8)
(411)
Northern Ireland
6.4
(0.4)
(4340)
39.6
(2.3)
(334)
70.2
(4.9)
(131)
Poland
0.9
(0.1)
(10,081)
37.8
(5.0)
(90)
73.7
(7.4)
(33)
Portugal
6.1
(0.5)
(3849)
41.3
(2.7)
(269)
73.4
(5.7)
(104)
Saudi Arabia
2.3
(0.4)
(3638)
27.5
(9.1)
(81)
56.7
(17.7)
(23)
Spain
1.9
(0.2)
(2121)
36.3
(5.0)
(114)
90.1
(3.5)
(41)
Murcia, Spain
7.0
(0.9)
(2621)
37.5
(4.6)
(193)
76.4
(9.4)
(80)
United States
7.8
(0.3)
(9282)
28.1
(2.3)
(752)
69.5
(3.2)
(205)
All
5.3
(0.1)
(76,775)
38.4
(0.9)
(4617)
70.9
(1.4)
(1701)
%
(SE)
(n)
%
(SE)
(n)
%
(SE)
(n)
χ 2
16
731.6*
53.7*
54.1*
III. Pooled countries
All countries
4.5
(0.1)
(113,226)
34.6
(0.8)
(5674)
70.0
(1.4)
(1897)
χ 2
24
1276.3*
150.4*
67.0*
Low/middle-income countries vs. high-income countries
Table 2
2Conditional and cumulative probabilities of obtaining helpful treatment for generalized anxiety disorder after each professional seen, among respondents with lifetime DSM-5 generalized anxiety disorder who obtained treatmentI. Conditional probabilities
of obtaining helpful
treatment
II. Cumulative probabilities
of obtaining helpful
treatment (n = 1897)
Table 3
3Conditional and cumulative probabilities of persistence in help-seeking after previous unhelpful treatment, among respondents with lifetime DSM-5 generalized anxiety disorder who obtained treatmentI. Conditional probabilities of persistence
in help-seeking
II. Cumulative probabilities of
persistence in help-seeking
(n = 1373)
Table 4
4Multivariable analysis of predictors of obtaining helpful treatment (person-level composite outcome) and of the decomposed encounter-level outcomes of helpful treatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatmentComposite outcome
Decomposed outcomes
Model 1:
Person-level relative-odds of
obtaining helpful
treatment
(regardless of the number of
professionals seen)
Model 2:
Encounter-level relative-odds of obtaining
helpful treatment from
a given professional
(pooled across professionals seen)
Model 3:
Encounter-level relative-odds of the respondent persist-
ing in help-seeking after prior unhelpful treatment
(pooled across all unhelpful treatments)
Prevalence
Multivariate
Prevalence
Multivariate
Prevalence
Multivariate
Mean/% (SE) OR (95% CI) Mean/%
(SE)
OR
(95% CI)
Mean/%
(SE)
OR
(95% CI)
Age of GAD onset (years)
29.4
(0.3) 1.01 (1.00-1.02) 28.4
(0.4)
1.02*
(1.01-1.02)
27.7
(0.4)
0.99
(0.98-1.00)
χ 2
1
2.63
22.41*
1.48
Female
67.3
(1.2) 1.18 (0.90-1.54) 66.8
(1.6)
1.21*
(1.03-1.41)
66.2
(1.8)
1.08
(0.85-1.39)
χ 2
1
1.47
5.51*
0.42
Marital Status
Never married
36.9
(1.2) 1.06 (0.80-1.42) 36.6
(1.5)
1.18*
(1.01-1.38)
36.2
(1.7)
0.85
(0.65-1.10)
Previously married
22.9
(1.2) 0.99 (0.71-1.36) 24.0
(1.6)
0.88
(0.73-1.06)
24.6
(1.8)
1.08
(0.80-1.46)
Currently married
40.2
(1.2) 1.00
-
39.4
(1.5)
1.00
-
39.2
(1.7)
1.00
-
χ 2
2
0.21
9.66*
2.03
Education
Low
13.7
(0.8) 0.63* (0.42-0.95) 15.1
(1.1)
0.62*
(0.48-0.80)
16.1
(1.4)
0.92
(0.66-1.28)
Low-average
23.7
(1.2) 0.79 (0.57-1.09) 23.3
(1.4)
0.95
(0.77-1.17)
23.2
(1.6)
0.86
(0.62-1.18)
High-average
31.9
(1.2) 0.80 (0.58-1.10) 30.6
(1.5)
0.96
(0.81-1.15)
30.0
(1.7)
0.80
(0.58-1.10)
Student
10.4
(0.8) 0.59* (0.36-0.99) 12.0
(1.2)
0.81
(0.59-1.11)
12.7
(1.5)
0.62*
(0.39-0.99)
High
20.2
(0.9) 1.00
-
19.0
(1.1)
1.00
-
18.0
(1.2)
1.00
-
χ 2
4
7.74
17.37*
4.43
Treatment delay (years) a
6.4
(0.3) 0.99 (0.98-1.00) 6.1
(0.3)
1.01*
(1.00-1.02)
6.2
(0.4)
0.98*
(0.96-0.99)
χ 2
1
1.95
4.24*
12.44*
Started GAD treatment > = 2000 (vs. 1990-1999)
52.6
(1.2) 0.78 (0.60-1.01) 45.5
(1.4)
1.22*
(1.06-1.40)
43.1
(1.5)
0.61*
(0.48-0.76)
χ 2
1
3.66
7.25*
18.38*
Treatment type b
Mental health specialist + psychotherapy
55.3
(1.2) 0.83 (0.62-1.12) 60.3
(1.6)
0.73*
(0.59-0.91)
61.9
(1.8)
1.33
(0.98-1.81)
Mental health specialist + medication
55.7
(1.4) 1.46* (1.05-2.02) 65.8
(1.6)
0.76*
(0.62-0.93)
67.8
(1.8)
2.00*
(1.50-2.67)
General medical
74.1
(1.1) 0.88 (0.63-1.22) 79.4
(1.2)
0.60*
(0.50-0.72)
81.5
(1.3)
1.56*
(1.14-2.14)
Complementary/alternative medicine
20.4
(1.0) 1.38 (0.97-1.97) 27.9
(1.5)
0.73*
(0.63-0.84)
30.1
(1.7)
1.99*
(1.43-2.77)
Human services
16.6
(0.9) 1.00
-
21.0
(1.4)
1.00
-
22.6
(1.6)
1.00
-
Stein et al. BMC Psychiatry
(2021) 21:392
Table 4
4Multivariable analysis of predictors of obtaining helpful treatment (person-level composite outcome) and of the decomposed encounter-level outcomes of helpfultreatment and persistence, among people with lifetime DSM-5 generalized anxiety disorder who obtained treatment
(Continued)
Composite outcome
Decomposed outcomes
Model 1:
Person-level relative-odds of
obtaining helpful
treatment
(regardless of the number of
professionals seen)
Model 2:
Encounter-level relative-odds of obtaining
helpful treatment from
a given professional
(pooled across professionals seen)
Model 3:
Encounter-level relative-odds of the respondent persist-
ing in help-seeking after prior unhelpful treatment
(pooled across all unhelpful treatments)
Prevalence
Multivariate
Prevalence
Multivariate
Prevalence
Multivariate
Mean/% (SE) OR (95% CI) Mean/%
(SE)
OR
(95% CI)
Mean/%
(SE)
OR
(95% CI)
χ 2
4
12.27*
50.39*
32.32*
Exactly 2 or more of the above
67.5
(1.1) 1.30 (0.89-1.89) 77.7
(1.1)
1.01
(0.75-1.35)
80.1
(1.2)
1.49*
(1.03-2.15)
χ 2
1
1.80
0.00
4.56*
χ 2
5
27.34*
77.21*
131.57*
Comorbidity
Number of comorbid disorders c
1.7
(0.0) 1.06 (0.92-1.21) 1.9
(0.0)
0.98
(0.91-1.06)
1.9
(0.0)
1.10
(0.98-1.24)
χ 2
1
0.67
0.20
2.56
Panic disorder or agoraphobia with/without panic 19.5
(1.0) 1.79* (1.22-2.62) 24.8
(1.7)
0.93
(0.78-1.12)
25.8
(1.9)
2.12*
(1.53-2.94)
χ 2
1
8.89*
0.57
20.15*
Major depressive disorder
51.3
(1.3) 1.21 (0.91-1.61) 51.4
(1.4)
1.26*
(1.07-1.49)
50.6
(1.6)
0.91
(0.69-1.20)
χ 2
1
1.64
7.83*
0.47
Bipolar disorder
10.9
(0.8) 1.40 (0.89-2.21) 12.9
(1.2)
1.18
(0.93-1.50)
13.3
(1.3)
1.15
(0.76-1.75)
χ 2
1
2.12
1.77
0.44
χ 2
4
24.46*
10.08*
42.86*
Childhood adversities
Family dysfunction d
31.4
(1.1) 0.75* (0.58-0.96) 31.8
(1.4)
0.93
(0.78-1.10)
32.4
(1.5)
0.73*
(0.57-0.93)
Other e
18.0
(0.9) 1.47* (1.09-1.99) 17.8
(1.1)
1.13
(0.95-1.34)
17.5
(1.2)
1.51*
(1.10-2.07)
χ 2
2
9.73*
2.84
12.06*
Global
χ 2
21
88.45*
181.41*
260.66*
Abbreviations:
CI confidence interval;
GAD generalized anxiety disorder;
OR odds ratio;
SE standard error
*Significant at .05 level, two-sided test
a
Treatment delay (years) = Age at first GAD treatment
-Age at onset of GAD
b
Treatment providers: mental health specialists (psychiatrist, psychiatric nurse, psychologist, psychiatric social worker, mental health counselor), primary care providers, human services providers (social worker or
counselor in a social services agency, spiritual advisor), and complementary/alternative medicine (other type of healer or self-help group)
c
Comorbid disorders include: panic disorder or agoraphobia with/without panic disorder, post-traumatic stress disorder, specific phobia, social phobia, major depressive disorder, bipolar disorder, alcohol and/or drug
abuse, and alcohol or drug dependence but not abuse
d
Family dysfunction includes: physical abuse, sexual abuse, neglect, parental mental disorder, parental substance use disorder, parental criminal behavior, and family violence
e
Authors' contributions Substantial contribution to the conception of the work: DJS, AEK, MGH, DVV, RCK made substantial contribution to the conception of the work, and AEK, NAS, DVV, RCK made substantial contribution to design of the work. DJS, SAG, AAH, JA, YA, RB, BB, GDG, PDJ, LD, OG, JMH, AK, EGK, VKM, SL, MEMM, JM, FNM, DN, JPV, KMS, MCV, MX, ZZ, RCK made substantial contribution to the acquisition of data. WTC, NAS, RCK made substantial contribution to data analysis, and all authors made substantial contribution to interpretation of data. DJS, AEK, AMR, NAS, HNZ, RCK drafted the work and all authors substantively revised the work. All authors approved the submitted version and agreed to both to be personally accountable for the author's own contributions and to ensure that questions related to the accuracy or integrity of any part of the work, even ones in which the author was not personally involved, are appropriately investigated, resolved, and the resolution documented in the literature.15Interdisciplinary Center Psychopathology and Emotion Regulation, University Medical Center Groningen, Groningen, Netherlands.16Competing interestsIn the past 3 years, RCK reports being a consultant for Datastat, Inc., RallyPoint Networks, Inc., Sage Pharmaceuticals, and Takeda. FNM reports non-financial support from Otsuka outside and not related to the submitted work. In the past 3 years LD has received untied educational grant funding from Indivior and Seqirus, not related to the submitted work. DJS has received research grants and/or honoraria from Lundbeck, Johnson & Johnson, Servier and Takeda. The remaining authors declare that they have no competing interests.
Gulbenkian Foundation, Foundation for Science and Technology (FCT) and Ministry of Health. The Saudi National Mental Health Survey (SNMHS) is conducted by the King Salman Center for Disability Research. It is funded by Saudi Basic Industries Corporation (SABIC), King Abdulaziz City for Science and Technology (KACST), Ministry of Health (Saudi Arabia), and King Saud University. Funding in-kind was provided by King Faisal Specialist Hospital and Research Center, and the Ministry of Economy and Planning, General Authority for Statistics. The Psychiatric Enquiry to General Population in Southeast Spain -Murcia (PEGASUS-Murcia) Project has been financed by the Regional Health Authorities of Murcia (Servicio Murciano de Salud and Consejería de Sanidad y Política Social) and Fundación para la Formación e Investigación Sanitarias (FFIS) of Murcia. The US National Comorbidity Survey Replication (NCS-R) is supported by the National Institute of Mental Health (NIMH; U01-MH60220) with supplemental support from the National Institute of Drug Abuse (NIDA), the Substance Abuse and Mental Health Services Administration (SAMHSA), the Robert Wood Johnson Foundation (RWJF. Ministry of Health. The Portuguese Mental Health Study was carried out by the Department of Mental Health, Faculty of Medical Sciences. NOVA University of Lisbon, with collaboration of the Portuguese Catholic University, and was funded by Champalimaud FoundationGrant 044708), and the John W. Alden Trust. A complete list of all within-country and cross-national WMH publications can beby the Polish Ministry of Health. The Portuguese Mental Health Study was carried out by the Department of Mental Health, Faculty of Med- ical Sciences, NOVA University of Lisbon, with collaboration of the Portu- guese Catholic University, and was funded by Champalimaud Foundation, Gulbenkian Foundation, Foundation for Science and Technology (FCT) and Ministry of Health. The Saudi National Mental Health Survey (SNMHS) is con- ducted by the King Salman Center for Disability Research. It is funded by Saudi Basic Industries Corporation (SABIC), King Abdulaziz City for Science and Technology (KACST), Ministry of Health (Saudi Arabia), and King Saud University. Funding in-kind was provided by King Faisal Specialist Hospital and Research Center, and the Ministry of Economy and Planning, General Authority for Statistics. The Psychiatric Enquiry to General Population in Southeast Spain -Murcia (PEGASUS-Murcia) Project has been financed by the Regional Health Authorities of Murcia (Servicio Murciano de Salud and Consejería de Sanidad y Política Social) and Fundación para la Formación e Investigación Sanitarias (FFIS) of Murcia. The US National Comorbidity Survey Replication (NCS-R) is supported by the National Institute of Mental Health (NIMH; U01-MH60220) with supplemental support from the National Institute of Drug Abuse (NIDA), the Substance Abuse and Mental Health Services Ad- ministration (SAMHSA), the Robert Wood Johnson Foundation (RWJF; Grant 044708), and the John W. Alden Trust. A complete list of all within-country and cross-national WMH publications can be found at http://www.hcp.med.harvard.edu/wmh/.
These organizations made data available to the WMH consortium through restricted data sharing agreements that do not allow us to release the data to third parties. The exception is that the U.S. data are available for secondary analysis via the Inter-University Consortium for. Availability of data and materials Access to the cross-national World Mental Health (WMH) data is governed by the organizations funding and responsible for survey data collection in each country. University of Buenos Aires (Argentina; BelgiumBrazilUniversity of Sao PauloPolitical and Social Research. Research and Ethics Committee of the School of MedicineAvailability of data and materials Access to the cross-national World Mental Health (WMH) data is governed by the organizations funding and responsible for survey data collection in each country. These organizations made data available to the WMH consor- tium through restricted data sharing agreements that do not allow us to re- lease the data to third parties. The exception is that the U.S. data are available for secondary analysis via the Inter-University Consortium for Polit- ical and Social Research (ICPSR), http://www.icpsr.umich.edu/icpsrweb/ICPSR/ this link: http://www.hcp.med.harvard. edu/wmh/ftpdir/WMH_Ethics_approval.pdf. They are: Bioethics Committee, School of Medicine, University of Buenos Aires (Argentina); the authority of Census and Statistics Act, 1905 (Australia); Ethics Committee of the Institute of Public Health (Federal Public Service Health, Food Chain Safety, and Environment) (Belgium); Research and Ethics Committee of the School of Medicine, University of Sao Paulo (Brazil);
Deputy Minister and head of the Executive Committee of the National Psychiatric Program (Bulgaria); Ethical committee of the National. Center of Public Health and AnalysesBulgariaDeputy Minister and head of the Executive Committee of the National Psychiatric Program (Bulgaria); Ethical committee of the National Center of Public Health and Analyses (Bulgaria);
Ethics Committee for the FES Social Foundation (Colombia). Ethics Committee for the FES Social Foundation (Colombia);
. Comité Institucional de Ética Universidad CES. Comité Institucional de Ética Universidad CES (Colombia-Medellin);
Ethics Scientific Committee of the Ministry of Health Iraq (Iraq); Human Subjects Committee for survey and field procedures in Eitanim-Kfar Shaul Hospital. IsraelEthics Scientific Committee of the Ministry of Health Iraq (Iraq); Human Subjects Committee for survey and field procedures in Eitanim-Kfar Shaul Hospital (Israel);
University of Balamand Faculty of Medicine Institutional Review Board (Lebanon); Ethics committee in research of the. MexicoKeio University School of Medicine; Jichi University School of Medicine; Juntendo University School of Medicine; Yamagata University School of Medicine (Japan ; National Institute of Psychiatry Ramon de la Fuente MuñizKeio University School of Medicine; Jichi University School of Medicine; Juntendo University School of Medicine; Ya- magata University School of Medicine (Japan); University of Balamand Faculty of Medicine Institutional Review Board (Lebanon); Ethics committee in re- search of the National Institute of Psychiatry Ramon de la Fuente Muñiz (Mexico);
. Ethics Committee of the Netherlands Institute of Mental Health and Addiction. Ethics Committee of the Netherlands Institute of Mental Health and Addiction (Netherlands);
Universidade Nova (Portugal); Office of Research Affairs at King Faisal Specialist Hospital and Research Center (Saudia Arabia); Ethical Committee of Sant Joan de Deu Serveis de Salut Mental and Ethical Committee of IMIMHospital del Mar Medical Research Institute. Ethics Committee, Faculdade de Ciencias Médicas. Komisja Bioetyczna (Bioethical Committee) of Instytut Psychiatrii i Neurologi (PolandSpain-MurciaThe Clinical Research Ethics Committee of the University Hospital Virgen de la Arrixaca of MurciaSpainKomisja Bioetyczna (Bioethical Committee) of Instytut Psychiatrii i Neurologi (Poland); Ethics Committee, Faculdade de Ciencias Médicas, Universidade Nova (Portugal); Office of Research Affairs at King Faisal Specialist Hospital and Research Center (Saudia Arabia); Ethical Committee of Sant Joan de Deu Serveis de Salut Mental and Ethical Commit- tee of IMIMHospital del Mar Medical Research Institute (Spain-Murcia); The Clinical Research Ethics Committee of the University Hospital Virgen de la Arrixaca of Murcia (Spain);
Human Subjects Committees of the Institute for Social Research at the University of Michigan and of. Harvard Medical School. Human Subjects Committees of the Institute for Social Research at the University of Michigan and of Harvard Medical School (USA)
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| Abstract Serotonin 5-HT2A receptors (5-HT2ARs) have been implicated in schizophrenia. However, postmortem studies on 5-HT2ARs expression and functionality in schizophrenia are scarce. The 5-HT2AR mRNA and immunoreactive protein expression were evaluated in postmortem tissue from dorsolateral prefrontal cortex (DLPFC) of antipsychotic-free (n = 18) and antipsychotic-treated (n = 9) subjects with schizophrenia, and matched controls (n = 27). Functional coupling of 5-HT2AR to G-proteins was tested by measuring the activation induced by the agonist (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride ((±)DOI) in antibody-capture [35S]GTPγS scintillation proximity assays (SPA). In antipsychotic-free schizophrenia subjects, 5-HT2AR mRNA expression and protein immunoreactivity in total homogenates was similar to controls. In contrast, in antipsychotic-treated schizophrenia subjects, lower mRNA expression (60±9% vs controls) and a trend to reduced protein immunoreactivity (86±5% vs antipsychotic-free subjects) just in membrane-enriched fractions was observed. [35S]GTPγS SPA revealed a significant ~6% higher stimulation of Gαi1-protein by (±)DOI in schizophrenia, whereas activation of the canonical Gαq/11-protein pathway by (±)DOI remained unchanged. Expression of Gαi1- and Gαq/11-proteins did not differ between groups. Accordingly, in rats chronically treated with clozapine, but not with haloperidol, a 30–40% reduction was observed in 5-HT2AR mRNA expression, 5-HT2AR protein immunoreactivity and [3H]ketanserin binding in brain cortical membranes. Overall, the data suggest a supersensitive 5-HT2AR signaling through inhibitory Gαi1-proteins in schizophrenia. Together with previous results, a dysfunctional pro-hallucinogenic agonist-sensitive 5-HT2AR conformation in postmortem DLPFC of subjects with schizophrenia is proposed. Atypical antipsychotic treatment would contribute to counterbalance this 5-HT2AR supersensitivity by reducing receptor expression. | 1,999,730 |
Introduction
Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are widespread mental health problems and both illnesses are associated with high recurrence, comorbidity, and they prove to be difficult to treat, so treatment resistance is not uncommon [1,2]. Pharmacologically managed very similarly with serotonergic based antidepressants [3], it remains, however, unclear how the serotonergic system is involved in the comorbid occurrence of GAD in the depressed state. Better neurobiological insights on the presence of comorbid GAD in MDD could be of considerable interest to fine-tune treatment algorithms in this difficult-totreat group and certainly in the medication-resistant state.
One possible target for investigation could be the G-protein coupled post-synaptic 5-HT 2 receptor, which have been found to be involved in the pathophysiology of mood and anxiety disorders, suicide ideation, and MDD treatment (non)response [4,5]. Animal and human studies have shown that the 5-HT 2A receptor is implicated in the context of anxiety-related behaviors and MDD (see review by [6]). In addition, 5-HT 2A receptor dysfunctions of frontolimbic processes are often observed in both GAD [7,8] and MDD patients [9]. Indeed, functional brain-imaging studies in MDD, as well as in GAD, have also demonstrated deregulated neuronal processing in the frontolimbic areas resulting in enhanced stress sensitivity disturbed emotion regulation processes, rumination, and worrying [10][11][12].
Recently, more attention has been given to the involvement of 'hostility' and 'anger' in the depressed state [13,14], which refers to an emotional state varying from mild annoyance to rage [15]. Moreover, elevated levels of multiple dimensions of anger characterize individuals who meet diagnostic criteria for GAD [16]. Here intolerance of uncertainty could be a critical construct underlying the pathophysiology of GAD, and maladaptive behavioral and cognitive reactivity (e.g., biased contextual interpretations of the situation, poor decision-making) may not only increase worry and anxiety [17], but intolerance of uncertainty may also mediate the relationship between GAD symptoms and anger [18]. There is some evidence that supports positive cortical 5-HT 2A receptor involvement in aggression, anger, and impulsivity [19]. Surprisingly, no studies have investigated serotonergic differences of comorbid GAD in the treatment-resistant depressed (MRD) state.
Consequently, we collected 20 antidepressant-free (unipolar) melancholic MRD patients (10 with current comorbid GAD) documented to be resistant to several pharmacological interventions, and to examine the influence of the 5-HT 2A receptor, we used SPECT and 4-amino-N-[1-[3-(4-fluorophenoxy) propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide ( 123 I-5-I-R91150) as the radioligand [20] focusing on the frontolimbic areas. We also assessed the symptom Checklist-90-R (SCL-90-R [21]) to further investigate the relationship between SCL-90-R subscales (including a range of psychological measures, besides depression and anxiety, cognitive and conative symptoms such as hostility) and the 5-HT 2A receptor BI, to enlarge our insights on the nature of the serotonergic involvement in the co-occurrence of GAD in patients diagnosed with MRD.
Although primary diagnosis was MRD for all patients, we hypothesized that MRD patients with comorbid GAD would display increased frontolimbic 5-HT 2A binding BI when compared to those without the GAD comorbidity. Although we explored whether any of the SCL-90-R subscale scores could be related to distinct 5-HT 2A receptor BI between MRD patients with or without comorbid GAD, we expected that higher anxiety and the hostility subscale scores would be related to frontolimbic 5-HT 2A binding BI.
Methods
Participants
In accordance with the guidelines laid down in the declaration of Helsinki (2004) this study was approved by the Ethical Board of the University Hospital of the Vrije Universiteit Brussel. All patients gave informed consent to participate in the study and for publication. Twenty MRD patients (female: male = 13:7; age = 45.70 years, SD = 9.52) were included using the Dutch version of the Mini-International Neuropsychiatric Interview (M.I.N.I., edition 5.0.0 based on DSM-IV [22]), and all were diagnosed with unipolar melancholic MDD. Depression severity was assessed with the Beck Depression Inventory (BDI-II-NL [23]). Ten patients (50% of the sample) were diagnosed with comorbid GAD. Comorbid psychosis, bipolarity, and substance abuse/dependence were exclusion criteria. Since increased 5-HT2 (A) receptor BI are reported in suicide victims [4], suicidal attempts during the current depressive episode were considered as an exclusion criterion. According to the Thase and Rush criteria [24], patients were considered at least stage III treatment resistant: all had at least a minimum of two unsuccessful treatment trials with SSRI/NSRI and one failed clinical trial with a TCA. After a washout period, all patients were free from antidepressant, neuroleptics and mood stabilizers for at least two weeks before scanning. Only benzodiazepines taken on steady dose were allowed. This study was part of a larger investigation examining brain 5-HT 2A receptor BI in medication-resistant depression. Given our recent focus on comorbidity in treatmentresistant depression and GAD [25], we re-examined our initial cohort of 21 MRD patients used in an rTMS treatment study [26]. For this study, only the baseline scans were included, before patients underwent the rTMS treatment. Detected retrospectively, one male patient (38 years) diagnosed with MRD and comorbid GAD had an additional opioid addiction (paracetamol codeine for diffuse pain symptoms). Since opioids can increase intrasynaptic levels of serotonin [27], this patient was not included in the current study, nor in another study examining the characterization of 5-HT2A receptor BI in MRD compared to age-and gender-matched drug-naive first episode MDD patients [28].
SCL-90-R
All patients were assessed with the Dutch version of the Symptom Checklist-90-R (SCL-90-R [21]). This 90-item self-report symptom inventory is designed to reflect psychological symptom patterns of psychiatric and medical patients [29]. On a five-point Likert scale, participants rate the degree to which they have experienced symptoms during the past week. The symptom dimensions in the Dutch version are labeled as somatization (SOM), insufficiency in thought and behavior (IN), interpersonal sensitivity (SEN), depression (DEP), anxiety (ANX), hostility (HOS), agoraphobia (AGO), sleeping problems (SLA), and rest symptoms not otherwise specified (REST). The mean value of all separate items is referred to as the Global Severity Index (GSI), an estimate of general psychological distress in psychiatric populations. Given that we were primarily interested in the first eight SCL-90-R subscales (and not the non-specified rest category), we only focused on SOM, IN, SEN, DEP, ANX, HOS, AGO, and SLA.
SPECT brain imaging
Static SPECT-imaging was performed with a Siemens Mul-tiSPECT triple-headed gamma camera, equipped with parallel-hole medium-energy collimators. For thyroid blockage all patients received oral Lugol's solution containing 400 mg of potassium iodide 15 min prior to injection of an average dose of 150 MBq 123 I-5-I-R91150. SPECT acquisition was performed at a minimum of 120 min after administration of the tracer. Data were collected from 96 angular positions over 360° in a 128 × 128 matrix, with a total acquisition time of 32 min. Reconstruction of the acquired projection images was performed using an iterative reconstruction algorithm (Ordered Subset Expectation Maximization, OSEM, 8 iterations, 8 subsets) and filtered with a 3D Gaussian using 15 mm full width at half-maximum.
SPECT scans were automatically co-registered to a template image placed in a predefined stereotactic (image) space (BRASS; Nuclear Diagnostics Ltd., Sweden) (See also [30]). The sequential acquisition of transmission and emission images was further used to anatomically standardize the emission image using the same linear parameters as those used for the transmission image [31]. All images were visually double-checked to ensure correct anatomical positioning of the predefined VOIs [32].
Radioactivity estimates in the volumes of interest (VOI) were assumed to represent total ligand binding (specific plus nonspecific binding plus free ligand) [32]. Since very few 5-HT 2A receptors are present in the cerebellum, this region was chosen to represent nonspecific activity [20]. Calculation of relative indices of specific BI was performed by VOI normalization to the activity per volume element in the cerebellum. Under these pseudo-equilibrium circumstances, BI is directly related to the in vivo receptor density (Bmax) and affinity (Kd). BI was defined as (target activity-background activity in the brain)/(background activity) which was operationally estimated as (counts/pixel in VOI-counts/pixel in the cerebellum)/(counts/pixel in the cerebellum) [31].
Given the relatively small study sample, for the analysis we limited our number of VOIs to six: the brainstem, the dorsolateral prefrontal cortex (left + right DLPFC), orbitofrontal cortex (left + right OFC), ventrolateral prefrontal cortex (left + right VLPFC), anterior cingulate cortex (left + right ACC), hippocampal-amygdala complex (left + right HippAM).
Statistical methods
All statistical analyses were performed with SPSS 25 (Statistical Package for the Social Sciences, IBM, Chicago, USA). Where necessary, we applied the Greenhouse-Geisser correction to ensure the assumption of sphericity. The significance level was set at p < 0.05, two-tailed, except for the SCL-90-R. Since the SCL-90-R was introduced for exploratory purposes and given that we were primarily interested in the first eight subscales, labeled SOM, IN, SEN, DEP, ANX, HOS, AGO, and SLA, for these eight subscale analyses with VOI 5-HT 2A receptor-binding indices, here the p value, twotailed was Bonferroni corrected for the number of significant VOIs derived and eight subscales, was set at p < 0.00625, two-tailed (Bonferroni correction).
Behavioral analysis
Concerning the behavioral outcome results, we compared demographics and SCL-90-R questionnaire scores between MRD patients with and without comorbid GAD with X 2 or t tests. See for details Table 1.
SPECT analysis
To test our hypothesis on 5-HT 2A receptor BI differences between depressed patients with and without comorbid GAD, first, in a MANCOVA analysis the six VOIs were analyzed as multiple dependent variables and MRD group (GAD versus no GAD) was the fixed between subjects' factor. Given that age-dependent reductions in 5-HT 2A receptor-binding indices have consistently been reported [33,34], we added age as covariate. Significant outcomes of the omnibus MANCOVA were followed up by univariate analyses. Second, to control whether 5-HT 2A receptor BI in these significant VOIs could be influenced by the individual daily dose intake of benzodiazepines (mg/day), the duration of the current depressive episode (years), suicide risk (MINI), or the individual depression severity scores (BDI-II), we performed an exploratory (partial) correlation analysis (corrected for age) for the entire sample and for each MRD group (GAD versus no GAD) separately. Third, to evaluate whether one of the eight symptom dimensions of the Dutch version of the SCL-90-R was related to any of the significant VOI 5-HT 2A receptor BI, again we performed an (partial) correlation analysis (corrected for age) between the significant VOIs and the eight SCL-90-R subscales for each MRD group separately (GAD versus no GAD), Bonferroni corrected. See Fig. 1.
Results
Demographics
MRD patients with (n = 10) or without GAD (n = 10) were not significantly different in age, gender distribution, benzodiazepine use, depression severity, or current episode duration. See Table 1. Of note, for one patient (in the MRD group with comorbid GAD), the SCL-90-R questionnaire went missing, so to evaluate the effects of SCL-90-R subscales only 19 patients were included. Here, we found that MRD patients with GAD scored significantly higher on insufficiency in thought and behavior (IN: p < 0.009) and nearly reached significance on Hostility (HOS; p = 0.052). Table 2.
Second, partial correlation analysis (controlled for age) showed no significant association between HippAM 5-HT 2A receptor BI and the use of benzodiazepines, depression severity, suicide risk, and the duration of the current depressive episode for the entire sample, as well for the two groups (GAD vs. no GAD) separately (p's > 0.01).
Third, because group differences were found to be significant only for the HippAM VOI, for the (partial) correlation analysis with the SCL-90-R subscales, here, the p value was set at p < 0.00625, two-tailed (Bonferroni correction for eight SCL-90-R subscales). To evaluate whether any SCL-90-R questionnaire scales were associated with HippAM 5 - Fig. 2. In addition, to assess the significance of the difference between the two correlation coefficients using the Fisher r-to-z transformation, which showed a significant difference (z = − 2.18, p = 0.03).
Finally, given the relatively small sample size and the potential influence of age differences between the two groups, as an additional manipulation check, we removed the oldest patient (female, 61 years, no GAD), and repeated all analyses. Besides that indeed there were no significant age differences between the two groups [t(17) = 1.52, p = 0.15], this did not affect any of the former outcome results, indicating that age was not a major influencer between the group analyses.
Discussion
MRD patients with a comorbid diagnosis of GAD scored higher on insufficiency in thought and behavior (IN), and on hostility (HOS). Both behaviors have been reported when clinically depressed and/or when diagnosed with GAD [3,15]. Whereas the IN dimension focuses on feelings of personal inadequacy and inferiority in comparisons with others-including self-deprecation, uneasiness, and discomfort during interpersonal interactions-higher scores on HOS indicates thoughts, feelings, or actions characteristic of the negative affect state of anger reflecting qualities such as aggression, irritability, rage and resentment [29]. Besides that, the demographics in both groups were similar (see Table 1), depression and anxiety SCL-90-R subscale scores did also not differ between the two groups, which suggests that the levels of depression and anxiety symptoms were not influenced by the occurrence of comorbid GAD in our MRD sample. Concerning our SPECT results, the lack of frontal cortical group 5-HT 2A receptor BI differences in our sample indicates that serotonergic influences may not differ in MRD with or without comorbid GAD, suggesting no top-down cognitive different influences from the frontal cortical areas [5]. Of note, findings concerning the frontal cortical 5-HT 2A receptor in the depressed state are not univocal, with some authors demonstrating 5-HT 2A receptor increases, and others demonstrating decreases, or no differences in receptor ligand binding at all [28]. On the other hand, the observed increased (hippocampal) amygdala 5-HT 2A receptor BI agrees with its modulating capacity of anxiety-states and anxiety-related behavior and are probably modulated by GABAergic interneurons in the (basolateral) amygdalae [35]. Of interest, in patients with Urbach-Wiethe disease, displaying severe bilateral amygdala damage, this syndrome has been associated with decreases in amygdala 5-HT 2A receptor density and related to decreased fear and anxiety behavioral manifestations [36]. In addition, because of its involvement in the hypothalamic-pituitary-adrenal (HPA)stress system, the role of the hippocampus in the glucocorticoid regulation of stress reactions is well known [37]. Here, the HPA-system is thought to be regulated by serotonin in hippocampal neurons [38,39], and especially by hippocampal 5-HT 2A receptor activation [40].
It is of interest to note that in patients suffering from Borderline Personality Disorder-an emotional unstable and stress-sensitive personality disorder characterized amongst other symptoms with separation anxiety, anger and impulse control disturbances-only hippocampal 5-HT 2A receptor binding was increased, independent of depressed mood [41]. Our (partial) correlation analysis showed that increases in HippAM 5-HT 2A receptor BI were related to higher scores on the SCL-90-R subscale score hostility (HOS) in the MRD state. Common with BPS symptoms, our exploratory partial correlation analysis also showed that increased HippAM 5-HT 2A receptor BI in relation to increased hostility could me especially apparent in MRD patients with comorbid GAD. In addition, GAD may lead to emotional dysregulation, including unsuppressed anger and low tolerance to frustration [42]. In addition, higher levels of anger and hostility contributed and predicted GAD symptom severity and elevated levels of multiple dimensions of anger characterized individuals who met the diagnostic criteria for GAD [16].
In preclinical studies, the involvement of the 5-HT 2A receptor in anxious behavior has been observed in dogs [43], and disinhibited aggressive behavior associates with an increased cortical uptake of the 5-HT 2A receptor radioligand 123 I-5-IR91150 [44]. Of interest, successful SSRI treatment in impulsive-aggressive dogs downregulated the cortical 5-HT 2A receptor BI also in the temporal cortical areas, in canine species regarded as part of the hippocampal complex [45]. In depressed adolescents, a single dose of fluoxetine also immediately reduced neural amygdala-hippocampal activity in response to angry facial expressions [46]. Furthermore, among outpatients with MDD early clinical improvement in anger/hostility symptoms may predict response to antidepressant treatment with fluoxetine [47]. It may of interest to note that, although we focused on 5-HT 2A receptor BI in the frontolimbic regions, with inclusion of the brainstem, the investigated VOIs are structurally connected to the medial forebrain bundle, primarily mediated by the dopaminergic system as being part of the reward pathway targeting similar brain regions also selected for our current 5-HT 2A post-synaptic receptor study (MFB; [48]). In TRD patients, these (superolateral) MFB has been recently the target areas for deep-brain stimulation (DBS; [49,50]) offering depressed patients unresponsive to several pharmacotherapeutic interventions an option to relief their mental burden. It would be of interest to verify in future DBS studies in depression whether clinical improvement also differentially attenuates hostility thoughts and actions in TRD patients diagnosed with or without GAD.
Patients diagnosed with GAD tend to avoid intense negative emotions by engaging in worry or behavioral avoidance, which may lead to an increase in emotional distress [51], displaying an elevated intolerance of uncertainty (IU) and anger [52]. Importantly, individual and group psychotherapeutic sessions targeting this IU construct in GAD patients may result not only in decreases in IU, but also on worrying and on angriness [18,53]. One could speculate that MRD patients with comorbid GAD may benefit from such specific additional psychotherapeutic interventions, impacting elevated HippAM 5-HT 2A receptor BI.
Besides the obvious limitation, the relatively small sample size, all interpretations should be limited to melancholic MRD patients. Since we have not contrasted our findings to a non-depressed group, a GAD group with no comorbid (treatment resistant) depressed episode, the absence of cortical group 5-HT 2A receptor BI only implies that in the MRD cohort frontal 5-HT 2A receptor densities are not significantly different with co-occurrence of GAD, and that the hippocampal-amygdala serotonergic findings are specific for the comorbid existence of MRD and GAD. A healthy control group could also have been informative to examine whether 5-HT 2A receptor VOI-binding indices would be any different between the healthy and the depressed state, and to evaluate whether in healthy samples hostility symptoms would also be related to higher HippAM 5-HT 2A receptor densities. Although MDD was the primary diagnosis, it remains possible that for some the diagnoses of GAD preceded the MDD episode, and not vice versa (e.g., [54]). We used the MINI as a diagnostic tool, but the severity of GAD symptoms was not examined with disease specific questionnaires. The MINI does also not include any personality diagnostic measurement. Although the amygdala and hippocampus may serve different neuronal and behavioral functions, the limited resolution of the SPECT scan prohibited clear disentanglement of 5-HT 2A receptor BI between the two anatomical structures [55]. Future PET ligand studies, more capable to delineate between hippocampus and amygdala could examine potential 5-HT 2A receptor BI regional differences. Of note, given the sample size of only 20 MRD patients, due to potential insufficient statistical power, the negative findings of the other VOIs may be a false negative. Since left and right VOIs were pooled due to the relatively small sample size, we cannot comment on possible lateralization influences.
In conclusion, the increased hippocampal-amygdala 5-HT 2A receptor BI found in depressed patients documented to be resistant to several antidepressant interventions and with the comorbid diagnosis of generalized anxiety could represent a serotonergic biomarker for this comorbid occurrence. Furthermore, the enhanced levels in hostility related to hippocampal-amygdala 5-HT 2A receptor BI in such kinds of patients displaying this comorbidity could indicate that adapted psychotherapeutic interventions may be warranted. It remains without saying that these preliminary findings should be replicated in larger clinical samples to substantiate our assumptions.
MDD major depressive disorder, GAD generalized anxiety disorder, BDI-II 21-item Beck Depression Inventory, F female, M male. Significance set at p < 0.05, two-tailed. Somatization (SOM), insufficiency in thought and behavior (IN), interpersonal sensitivity (SEN), depression (DEP), anxiety (ANX), hostility (HOS), agoraphobia (AGO), sleeping problems (SLA), and rest symptoms not otherwise specified (REST), Global Severity Index (GSI) *In medians and interquartile ranges
of the zero order correlation showed that there was a significant positive correlation between the HippAM 5-HT 2A receptor BI and hostility (HOS) only, r(17) = 0.59, p = 0.004, indicating that controlling for age had little effect on the strength of the relationship between the two variables. Separate explorative correlation analyses (not Bonferroni corrected) were separately performed in MRD patients with GAD and without GAD to further investigate whether the HippAM 5-HT 2A receptor BI and HOS correlation were any different between the two groups. Pearson partial correlation analysis showed that there was no significant correlation between both variables [r(8)= − 0.27, p = 0.23] in MRD patients without comorbid GAD. However, in MRD patients diagnosed with comorbid GAD, Pearson partial correlation analysis revealed a positive correlation between HippAM 5-HT 2A receptor BI and the individual HOS scores [r(7) = 0.71, p = 0.02]. See also
Fig. 2
2Scatter plots between the individual scores on hostility (HOS) (x-axis) and Hippocampal amygdala 5-HT 2A receptor BI complex (y-axis) for the entire medication-resistant depressed (MRD) sample (straight thin full line), and plotted separately for MRD patients with generalized anxiety disorder (GAD) (thick full line and full bullets) and without comorbid GAD (dashed thick line and open bullets). Of note, the lines representing the least-squares fit to the data are not corrected for age
Table 1 Demographics
1Data are presented as ratio, means and standard deviations
Table 2
2VOI 5-HT 2A receptor BI Univariate analysis VOIs Volumes of interest, DLPFC the brainstem, the dorsolateral prefrontal cortex, VLPFC ventrolateral prefrontal cortex, OFC orbital prefrontal cortex, ACC anterior cingulate cortex, HippAM hippocampalamygdala complexAll p values are age corrected
5-HT 2A receptor BI
All MRD patients
Without GAD
With GAD
F test
p value
VOIs
DLPFC
104.50 (6.50)
104.69 (7.15)
104.32 (6.17)
0.05
0.83
VLPFC
107.71 (4.31)
108.05 (4.56)
107.38 (4.27)
0.34
0.57
OFC
107.85 (10.32)
107.33 (9.63)
108.38 (11.47)
0.35
0.56
ACC
106.68 (5.97)
107.35 (5.74)
106.01 (6.42)
< 0.01
0.97
HippAM
267.05 (111.05)
232.62 (68.80)
301.48 (136.64)
5.08
0.038
Brainstem
125.26 (16.27)
126.23 (17.98)
124.29 (15.27)
0.02
0.88
Funding (Information that explains whether and by whom the research was supported). This research was supported by the National Natural
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The role of neurotrophic factors in adult hippocampal neurogenesis, antidepressant treatments and animal models of depressive-like behavior. H D Schmidt, R S Duman, 10.1097/FBP.0b013e3282ee2aa8Behav Pharmacol. 18Schmidt HD, Duman RS (2007) The role of neurotrophic factors in adult hippocampal neurogenesis, antidepressant treatments and animal models of depressive-like behavior. Behav Pharmacol 18:391-418. https:// doi. org/ 10. 1097/ FBP. 0b013 e3282 ee2aa8
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Evaluation of the brain 5-HT2A receptor binding index in dogs with anxiety disorders, measured with 123I-5I-R91150 and SPECT. S T Vermeire, K R Audenaert, A A Dobbeleir, De Meester, R H , De Vos, F J Peremans, K Y , 10.2967/jnumed.108.055731J Nucl Med. 50Vermeire ST, Audenaert KR, Dobbeleir AA, De Meester RH, De Vos FJ, Peremans KY (2009) Evaluation of the brain 5-HT2A recep- tor binding index in dogs with anxiety disorders, measured with 123I-5I-R91150 and SPECT. J Nucl Med 50:284-289. https:// doi. org/ 10. 2967/ jnumed. 108. 055731
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A single dose of fluoxetine reduces neural limbic responses to anger in depressed adolescents. L P Capitão, R Chapman, S E Murphy, C J Harvey, A James, P J Cowen, C J Harmer, 10.1038/s41398-018-0332-2Transl Psychiatry. 930Capitão LP, Chapman R, Murphy SE, Harvey CJ, James A, Cowen PJ, Harmer CJ (2019) A single dose of fluoxetine reduces neural lim- bic responses to anger in depressed adolescents. Transl Psychiatry 9:30. https:// doi. org/ 10. 1038/ s41398-018-0332-2
Early improvements in anxiety, depression, and anger/hostility symptoms and response to antidepressant treatment. A Farabaugh, S Sonawalla, D P Johnson, J Witte, G I Papakostas, T Goodness, A Clain, L Baer, D Mischoulon, M Fava, R Harley, Ann Clin Psychiatry. 22Farabaugh A, Sonawalla S, Johnson DP, Witte J, Papakostas GI, Goodness T, Clain A, Baer L, Mischoulon D, Fava M, Harley R (2010) Early improvements in anxiety, depression, and anger/hostil- ity symptoms and response to antidepressant treatment. Ann Clin Psychiatry 22:166-171
A review of white matter microstructure alterations of pathways of the reward circuit in depression. T Bracht, D Linden, P Keedwell, J Affect Disord. 187Bracht T, Linden D, Keedwell P (2015) A review of white mat- ter microstructure alterations of pathways of the reward circuit in depression. J Affect Disord 187:45-53
A longitudinal study on deep brain stimulation of the medial forebrain bundle for treatment-resistant depression. A J Fenoy, P E Schulz, S Selvaraj, C L Burrows, G Zunta-Soares, K Durkin, P Zanotti-Fregonara, J Quevedo, J C Soares, Transl Psychiatry. 8111Fenoy AJ, Schulz PE, Selvaraj S, Burrows CL, Zunta-Soares G, Durkin K, Zanotti-Fregonara P, Quevedo J, Soares JC (2018) A lon- gitudinal study on deep brain stimulation of the medial forebrain bundle for treatment-resistant depression. Transl Psychiatry 8:111
Neuromodulation in psychiatric disorders: experimental and clinical evidence for reward and motivation network deep brain stimulation: focus on the medial forebrain bundle. M D Döbrössy, C Ramanathan, Ashouri Vajari, D Tong, Y Schlaepfer, T Coenen, V A , Eur J Neurosci. 53Döbrössy MD, Ramanathan C, Ashouri Vajari D, Tong Y, Schlaep- fer T, Coenen VA (2021) Neuromodulation in psychiatric disorders: experimental and clinical evidence for reward and motivation net- work deep brain stimulation: focus on the medial forebrain bundle. Eur J Neurosci 53:89-113
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Intolerance of uncertainty mediates the relation between generalized anxiety disorder symptoms and anger. K Fracalanza, N Koerner, S S Deschênes, M J Dugas, 10.1080/16506073.2014.888754Cognit Behav Ther. 43Fracalanza K, Koerner N, Deschênes SS, Dugas MJ (2014) Intoler- ance of uncertainty mediates the relation between generalized anxi- ety disorder symptoms and anger. Cognit Behav Ther 43:122-132. https:// doi. org/ 10. 1080/ 16506 073. 2014. 888754
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Depression and generalized anxiety disorder: cumulative and sequential comorbidity in a birth cohort followed prospectively to age 32 years. T E Moffitt, H Harrington, A Caspi, J Kim-Cohen, D Goldberg, A M Gregory, R Poulton, 10.1001/archpsyc.64.6.651Arch Gen Psychiatry. 64Moffitt TE, Harrington H, Caspi A, Kim-Cohen J, Goldberg D, Gregory AM, Poulton R (2007) Depression and generalized anxi- ety disorder: cumulative and sequential comorbidity in a birth cohort followed prospectively to age 32 years. Arch Gen Psychiatry 64:651-660. https:// doi. org/ 10. 1001/ archp syc. 64.6. 651
Neuronal localization of the 5-HT2 receptor family in the amygdaloid complex. C Bombardi, 10.3389/fphar.2014.00068Front Pharmacol. 568Bombardi C (2014) Neuronal localization of the 5-HT2 receptor family in the amygdaloid complex. Front Pharmacol 5:68. https:// doi. org/ 10. 3389/ fphar. 2014. 00068
| Anxiety disorders are prevalent across the United States and result in a large personal and societal burden. Currently, numerous therapeutic and pharmaceutical treatment options exist. However, drugs to classical receptor targets have shown limited efficacy and often come with unpleasant side effects, highlighting the need to identify novel targets involved in the etiology and treatment of anxiety disorders. GPR83, a recently deorphanized receptor activated by the abundant neuropeptide PEN, has also been identified as a glucocorticoid regulated receptor (and named GIR) suggesting that this receptor may be involved in stress-responses that underlie anxiety. Consistent with this, GPR83 null mice have been found to be resistant to stress-induced anxiety. However, studies examining the role of GPR83 within specific brain regions or potential sex differences have been lacking. In this study, we investigate anxiety-related behaviors in male and female mice with global knockout and following local GPR83 knockdown in female mice. We find that a global knockdown of GPR83 has minimal impact on anxiety-like behaviors in female mice and a decrease in anxiety-related behaviors in male mice. In contrast, a local GPR83 knockdown in the basolateral amygdala leads to more anxiety-related behaviors in female mice. Local GPR83 knockdown in the central amygdala or nucleus accumbens (NAc) showed no significant effect on anxietyrelated behaviors. Finally, dexamethasone administration leads to a significant decrease in receptor expression in the amygdala and NAc of female mice. Together, our studies uncover a significant, but divergent role for GPR83 in different brain regions in the regulation of anxiety-related behaviors, which is furthermore dependent on sex. | Abstract Ten outpatients suffering from anxiety states (Anxiety Disorders: DSM-III) were treated with L -5-hydroxytryptophan and carbidopa. A significant reduction in anxiety was observed on three different anxiety scales. It is suggested that 5-HT systems may be involved in the mediation of anxiety. | Background: Generalized anxiety disorder (GAD) can significantly impair quality of life and is associated with a relatively poor long-term prognosis. Anxiety disorders are often associated with hyper-responsiveness to threat, perhaps coupled with impaired executive functioning. However, GAD, particularly adolescent GAD, has been the focus of little functional neuroimaging work compared to other anxiety disorders.Here, we examine the neural association of adolescent GAD with responsiveness to threat and response control.Methods:The study involved 35 adolescents with GAD and 34 healthy comparison individuals (N = 69) matched on age, gender, and IQ. Participants were scanned during an affective number Stroop task.Results:We found significant Group-by-Task Condition interactions in regions involved in response control/motor responding (bilateral precentral gyri and cerebellum) and/or cognitive control/attention (dorsomedial and lateral frontal cortex, posterior cingulate cortex, cuneus, and precuneus). In line with predictions, the youth with GAD showed significantly less recruitment during task trials than the healthy comparison individuals. However, no indications of specific heightened responses to threat were seen.Conclusions: GAD involves reduced capacity for engaging regions involved in re-sponse control/motor responding and/or cognitive control/attention. This might reflect either a secondary consequence of the patient's worry or an early risk factor for the development of worry. K E Y W O R D S anxiety disorders, attention, brain imaging/neuroimaging, functional MRI, GAD/generalized anxiety disorder S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Bashford-Largo J, Aloi J, Lukoff J, et al. Reduced top-down attentional control in adolescents with generalized anxiety disorder. Brain Behav. 2021;11:e01994. | BACKGROUND: Rodent approach-avoidance conflict tests are common preclinical models of human anxiety disorder. Their translational validity mainly rests on the observation that anxiolytic drugs reduce rodent anxiety-like behavior. Here, we capitalized on a recently developed approach-avoidance conflict computer game to investigate the impact of benzodiazepines and of amygdala lesions on putative human anxiety-like behavior. In successive epochs of this game, participants collect monetary tokens on a spatial grid while under threat of virtual predation. METHODS: In a preregistered, randomized, double-blind, placebo-controlled trial, we tested the effect of a single dose (1 mg) of lorazepam (n 5 59). We then compared 2 patients with bilateral amygdala lesions due to Urbach-Wiethe syndrome with age-and gender-matched control participants (n 5 17). Based on a previous report, the primary outcome measure was the effect of intra-epoch time (i.e., an adaptation to increasing potential loss) on presence in the safe quadrant of the spatial grid. We hypothesized reduced loss adaptation in this measure under lorazepam and in patients with amygdala lesions. RESULTS: Lorazepam and amygdala lesions reduced loss adaptation in the primary outcome measure. We found similar results in several secondary outcome measures. The relative reduction of anxiety-like behavior in patients with amygdala lesions was qualitatively and quantitatively indistinguishable from an impact of anterior hippocampus lesions found in a previous report. CONCLUSIONS: Our results establish the translational validity of human approach-avoidance conflict tests in terms of anxiolytic drug action. We identified the amygdala, in addition to the hippocampus, as a critical structure in human anxiety-like behavior. | Major depressive disorder (MDD) is one of the most common neuropsychiatric disorders affecting over one-fifth of the population worldwide. Owing to our limited understanding of the pathophysiology of MDD, the quest for finding novel antidepressant drug targets is severely impeded. Monoamine hypothesis of MDD provides a robust theoretical framework, forming the core of a large jigsaw puzzle, around which we must look for the vital missing pieces. Growing evidence suggests that the glial loss observed in key regions of the limbic system in depressed patients, at least partly, accounts for the structural and cognitive manifestations of MDD. Studies in animal models have subsequently hinted at the possibility that the glial atrophy may play a causative role in the precipitation of depressive symptoms. Antidepressants as well as monoamine neurotransmitters exert profound effects on the gene expression and metabolism in astrocytes. This raises an intriguing possibility that the astrocytes may play a central role alongside neurons in the behavioral effects of antidepressant drugs. In this article, we discuss the gene expression and metabolic changes brought about by antidepressants in astrocytes, which could be of relevance to synaptic plasticity and behavioral effects of antidepressant treatments. | In light of the poor reliability and discriminant validity of the DSM-III-R criteria for generalized anxiety disorder (GAD), extensive modifications were implemented in the development of the DSM-IV criteria. This study compares the discriminant validity of the DSM-III-R and DSM-IV criteria for GAD using data from a study of the familial aggregation of anxiety disorders and alcoholism. Based on information from a semi-structured diagnostic interview, both the DSM-III-R and DSM-IV associated symptom criteria were applied to characterize directly interviewed spouses and relatives of probands. The criterion-related and discriminant validity of the DSM-IV revised criteria were assessed according to the following clinical criteria: lifetime and concurrent comorbidity with depressive disorder and lifetime comorbidity with panic disorder. Subjects who met the DSM-IV associated symptom with and without comorbid depression were then compared on rates of treatment, psychotropic medication use, impairment, age at onset and presence of a psychosocial stressor at onset. No differences were found in the discriminant validity of the DSM-III-R versus DSM-IV definitions of GAD. It is postulated that the lack of difference in validity between the two diagnostic systems is due to the low prevalence of autonomic hyperactivity symptoms associated with GAD. Implications for the nosology of GAD and its relationship with other anxiety disorders are discussed. Copyright © 1999 Whurr Publishers Ltd. | Convergent neurobiological predictors of mood and anxiety symptoms and treatment response. | Treatment-emergent suicidal ideation and behavior are ongoing concerns with antidepressants. Vilazodone, currently approved for the treatment of major depressive disorder (MDD) in adults, has also been evaluated in generalized anxiety disorder (GAD). Post-hoc analyses of vilazodone trials were carried out to examine its effects on suicidal ideation and behavior in adults with MDD or GAD. Data were pooled from vilazodone trials in MDD (four studies) and GAD (three studies). The incidence of suiciderelated events was analyzed on the basis of treatmentemergent adverse event reporting and Columbia-Suicide Severity Rating Scale (C-SSRS) monitoring. Treatmentemergent suicidal ideation was analyzed on the basis of a C-SSRS category shift from no suicidal ideation/behavior (C-SSRS = 0) at baseline to suicide ideation (C-SSRS = 1-5) during treatment. In pooled safety populations (MDD, n = 2233; GAD, n = 1475), suicide-related treatmentemergent adverse events occurred in less than 1% of vilazodone-treated and placebo-treated patients. Incidences of C-SSRS suicidal ideation were as follows: MDD (vilazodone = 19.9%, placebo = 24.7%); GAD (vilazodone = 7.7%, placebo = 9.4%). Shifts from no suicidal ideation/behavior at baseline to suicidal ideation during treatment were as follows: MDD (vilazodone = 9.4%, placebo = 10.3%); GAD (vilazodone = 4.4%, placebo = 6.1%). Data from placebo-controlled studies indicate little or no risk of treatment-emergent suicidal ideation or behavior with vilazodone in adults with MDD or GAD. Nevertheless, all patients should be monitored for suicidal thoughts and behaviors during antidepressant treatment. Int Clin Psychopharmacol 32:281-288 |
1,999,731 | Gender analysis of entrepreneurial intentions as a function of economic development across three groups of countries | This empirical study aims at assessing the attitudes, perception and intention of university students towards entrepreneurship and new venture creation with a focus on gender differences in entrepreneurial perceptions and intentions to start new business in the future. Data were collected using a questionnaire-based survey of 350 students at the University of Khartoum in Sudan. The target population was the students in the final year in the University of Khartoum. The stratified sampling technique was used to select the sample size because the population consisted of a number of subgroups that differed in their characteristics. The results showed significant differences between genders in entrepreneurial intentions and its antecedents. Thus, it is important that customized approaches based on gender are needed for developing entrepreneurial intentions among college students. | Although many researchers agree that environmental and personal characteristics are important for becoming an entrepreneur, it is still not clear if their influence is equally significant. Numerous authors have pointed out unresolved matters regarding the relationship among innovativeness, gender, and entrepreneurial intensions. The aim of this paper is to explore the impact of gender and country of origin in relation to entrepreneurial intentions and innovative cognitive style. Research was conducted using a sample of students majoring in information and communication technologies from Croatia and Slovenia. The results revealed the influence of gender, country, attitudes toward entrepreneurship, and innovative cognitive style on entrepreneurial intentions. | This study examines the effect of gender on students' entrepreneurial intentions in the Czech Republic, a country that exhibits a particular transition economy context with private entrepreneurship being relatively recent. While gender equality is in general legislatively enshrined in Czech society, one can ask whether in reality gender equality displays in the entrepreneurial intentions of students. Our theoretical framework is based on Ajzen's theory of planned behaviour. Based on a survey of 200 students, our results show that gender and level of entrepreneurial intentions are not independent. We examine the phenomenon by considering the beliefs, antecedents of intention, and we find noticeable gender-related differences in their nature. The contribution of this article is two-fold. First, we show that entrepreneurial intentions are slightly gendered. Secondly, we analyse which determinants of these intentions following the Ajzen's theory of planned behaviour are concerned and discuss the way to act upon. | The influence of sex and gender-role orientation in the decision to become an entrepreneur | Using 2005 firm level data for 26 ECA countries, this paper estimates performance gaps between male- and female-owned businesses, while controlling for their location by industry and country. We find that female entrepreneurs have significantly smaller scale of operations (as measured by sales revenues) and are less efficient in terms of Total Factor Productivity (TFP), although this difference is very small. However, they generate the same amount of profit per unit of revenue as men. We find that while both male and female entrepreneurs in ECA are sub-optimally small, women's returns to scale are significantly larger than men's implying that they would gain more from increasing their scale. We argue that the main reasons for the sub-optimal size of female-owned firms are that they are both capital constrained and concentrated in industries with small firms. | It is suggested that more “role model” women entrepreneurs are needed. However, the gender gap in entrepreneurship remains. This study analyses the narratives of 51 role model women entrepreneurs t... | The main emphasis of this study is to examine the role of gender as a moderator between entrepreneurship intention and its predictors among university graduates in Nigeria and India. The data were gathered from 130 postgraduate students from two universities in Abuja and a southern region of India. A structured questionnaire was administered on-line via Google document. Confirmatory Factor Analysis of Structural Equation Modelling (SEM) was used to determine the relationship between the independent and dependent variables. The study shows that gender has a moderating effect on entrepreneurship intentions due to subjective norms, perceived behavioural control and attitude towards the behaviour. The study recommends total annihilation of gender differences in building entrepreneurship process and to nurture both genders in the same way to build strong personalities. ::: ::: ::: ::: Key words: Attitude towards behaviour, entrepreneurial intention, gender, perceived behavioural control, and subjective norms. | Entrepreneurs make an important contribution in the growth and development of any nation. Globalisation has made way for women entrepreneurs to become an important contributor to economic development and social development. In India, women make nearly 50 percent of the country’s population, and having the right mix of skills for being successful in business, they need to be encouraged by all possible means. In recent times, despite all social and financial barriers, women entrepreneurs are fast emerging as a force to reckon with. The current paper focuses on women entrepreneurship. It aims at defining the concept of women entrepreneurship and discusses the current status of women entrepreneurship in India. The paper discusses the inherent traits possessed by women that facilitate and ensures their success as entrepreneurs. The paper also aims at identifying the challenges and barriers encountered by women entrepreneurs in starting and running their own business. | 1,999,731 | The aim of this paper is to analyze the gender differences in entrepreneurial intentions by studying a range of socioeconomic and psychosocial factors. Furthermore, we aim at analyzing these differences in three groups of countries depending on the stage of economic development of each country according to the Global Competitiveness Report. Using a logistic regression analysis and data from the 2008 APS (Adult Population Survey) database which is part of the Project GEM (Global Entrepreneurship Monitor), results show the existence of gender differences in entrepreneurial intentions. The model proposed in the study has decreasing explanatory power as the degree of economic development increases, and is also more conclusive for men than women. An important methodological innovation we implemented in the current study is the use of the variable gender as a dependent variable rather than a variable of a socio demographic nature. | Gender Differences in Entrepreneurial Attitude & Intentions among university Students | Understanding parental and gender impact on entrepreneurial intentions | The aim of the study is to investigate empirically whether there is a significant difference in the entrepreneurial intention of students whose parents run a business and those whose parents do not run a business. In addition, the study aims to investigate whether there is a significant gender difference in the entrepreneurial intention of students. The study focussed on the final year students (undergraduate level) in the Department of Business Management of a South African university. These are students that have done entrepreneurship and small business management modules. This study made use of convenience sampling. Data was collected through the use of self-administered questionnaire in a survey. Data analysis included descriptive statistics and the T-test. The results indicate that although male students have a higher level of entrepreneurial intention compared to female students, the difference is not statistically significant. The results also indicate that students whose parents are involved in business have a higher level of entrepreneurial intention compared to students whose parents are not involved in business. However, the difference is not statistically significant. DOI: 10.5901/mjss.2014.v5n7p157 | Gender and entrepreneurial intentions in a transition economy context: case of the Czech Republic | Role of entrepreneur gender and management style in influencing perceptions and behaviors of new recruits: Evidence from the Islamic Republic of Iran | Gender as a moderator between entrepreneurship intention and its predictors among university graduates in Nigeria and India | Intrinsic entrepreneurial motivation factors: gender differences | The moderating effect of demographic characteristics on the relationship between strategic capabilities and firm performance in women-owned entrepreneurial ventures in Nairobi, Kenya |
1,999,732 | [SELL] [OFFER] Destash! Open to offers! - Make Up For Ever, Jouer, Cover FX, Chanel, Too Faced, Urban Decay, Laura Mercier, Iconic London, Tarte, Artis | I'm offering 1.5m per 7-11 piece offered either with or without items off my trade lists.
[DLC trade list] (
[Floor trade list] (
[Furniture trade list] (
[Wall trade list] (
Here's my want lists
[Preferred want list] (
[Full want lists] (
EDIT: Thanks much to /u/FunkmasterFritz, /u/effest, and /u/padfoot6. I should have left this when I posted but if you could check out my [RMM] ( I'd appreciate the feedback.
To anyone else looking, I'll be online for a while taking offers. | You have to sign up for Hautelook, but that's the only 'catch'!
Brushes, blushes, bronzers, brows and more all on sale. (Dat alliteration).
Link to the sale | **[SELL/RELOCATION]** 35mil/Offer
Lavender Beds, Plot 1
No furniture left behind.
**[FC HOME]** 50mil/Offer
Mist, Plot 44
Maxed Maelstrom
Rank 10
FC Chest will be emptied.
No furniture left behind.
137.774 C*
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Going to Crystal server. Time to sell before next year comes. Taking offers. | (Android)
Selling 94 yashin, 95 Pele, 88 seedorf, 87 lineker, 2 x 86 puyol, 85 Rui costa, and 85 seedorf.
I also have totw 93 neymar, totw 89 Rodriguez and all star nominee casemeiro and a load of other specials.
Looking for koulibaily all star nominee, 89 hierro, 91/86 trezeguet, 88 Veron, 89 van basten, 87 Moore, 2 x any Socrates, 2x any weah/Zidane and any french icons. | Timestamp
Hey Mech peeps,
I'm looking to trade some artisans. I'm looking for DisCat
I'm open to any colorway that you have. I've been looking ever since I missed the B & W Raffle. Willing to go 1:1 or add pp.
Please help me find this cap.
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|Ritual master|Night Mutant|trades|
|:-|:-|:-|
|Ritual master|Speaker|trades|
|Strider |Hiryu|trades|
|Clutch|The child|trades for other colorways|
|Bad Habit|Summer wave|trades|
|Sodie caps|Elok Ripper|trades|
|Rathcaps|Keyribohn|trades|
|Keyluminati|Arctic Inner Demon|sell $60 shipped|
|Girlycaps|Oasis Eldamar|trades|
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&#x200B; | I am looking to sell a variety of things, and am having very little luck in-game (I should really find a guild with a trader...). I haven't really had the chance to check a bunch of traders for values, so please message with offers; I typically just use ESO Price Check as a way to gauge general value.
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* Motif: Mercenary Legs
* Motif: Yokudan Maces
* Motif: Yokudan Shoulders
* Motif: Celestial Legs
* Motif: Celestial Bows
* Motif: Celestial Helms
* Consumable: Witchmother's Potent Brew (NOT the recipe)
* Consumable: Double Bloody Mara (NOT the recipe)
* Sealed Blacksmithing Writ: Rubidite Mace, Legendary, Training, Kagrenac's Hope, Draugr, 100 Writ Vouchers
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Thanks for taking a look! | Seeing as how this offer still having request, I have 10 more postcards but with random quotes on it for those that missed the first offer. If anyone interested, please comment below as well as sending your address in PM. | I'm looking for HA Dream ball Morelull in exchange for anything on this list.
Thanks! | 1,999,732 | Needing to do a de-stash! PLEASE MAKE OFFERS! I'm really keen to sell! I'm always open to reasonable offers!!
Postage is $8.50 tracked or $3 untracked for a large letter in a bubble mailer.
PayPal, F&F, if G&S I'll need to add PP fees on.
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1,999,733 | We analysed the relationship between the chemical complex (concentration of dissolved ions, nutrients, pH) and biological parameters (primary production, biomass of phytoplankton, abundance and activity of bacterial communities) at estuaries of rivers and coastal waters of Southern Baikal during the under-ice period. correlation network analysis revealed co 2 to be the main limiting factor for the development of algae and microbial communities in the coastal zone of Lake Baikal. this study indicates that primarily reverse synthesis of bicarbonate and carbonate ions associated with the development of phytoplankton and accumulation of dissolved co 2 during photosynthesis regulates pH in the Baikal water. We did not detect the anthropogenic factors that influence the change in pH and acidification. Near the Listvyanka settlement (Lake Baikal, Listvennichnaya Bay), there was a great number of organotrophs and thermotolerant bacteria with low bacterioplankton activity and high concentration of organic carbon. This evidences eutrophication due to the influx of organic matter having an anthropogenic source. nutrients produced during the bacterial destruction of this matter may explain the changes in bottom phytocenoses of Listvennichnaya Bay. |
INTRODUCTION
Dissolved inorganic carbon (DIC) exists in aquatic systems as unionized carbon dioxide, whether present as H 2 CO 3 or as CO 2 , and ionized species as HCO 3 and CO 3 2-. DIC is by far the greatest 'active' carbon reservoir at the Earth's surface. It has a mass equivalent to almost eight times the total comprised by other carbon reservoirs like atmospheric CO 2 , land plants, seawater dissolved organic carbon, soil humus, soil carbonate and surface marine sediment organic carbon (Hedges, 1992). This is relevant because directly or indirectly the entire biosphere depends on inorganic carbon as the major nutrient for primary producers.
In aquatic systems physical, chemical and biological processes influence inorganic carbon concentration. Atmospheric carbon dioxide concentrations, wind speed, pH, salinity, carbonates, depth, temperature, alkalinity, respiration, and photosynthesis are factors that typically affect DIC concentrations. Thus, diel variations in DIC concentrations may be used for evaluations of net biological activity of aquatic communities only after corrections for physical and chemical processes.
From these interactions DIC has been corelated to a variety of environmental issues, such as: (i) the recent (post-Industrial Revolution) increasing in atmospheric CO 2 levels (from ca. 275 to 355 ppmv), which may affect the current planetary feedback mechanisms (Falkowski, 1994), (ii) vertical fluxes of carbon from trophogenic to tropholitic zone (biological pump) (Hansell et al., 1997) and, (iii) metabolism of aquatic systems (autotrophic-production vs. heterotrophic-mineralization), which is ecologically related to their structure and function (Carmouze et al., 1991(Carmouze et al., , 1994del Giorgio & Peters, 1993;Souza & Couto, 1999). Other issues related to DIC are the influence of pCO 2(aq) on the stable carbon isotopic fractionation (e.g. δ 13 C) by microalgae (Wainright & Fry, 1994), and, in a minor extent, CO 2(aq) as limiting factor of microalgae growth (Riebesell et al., 1993;Raven, 1993).
Based on variations of DIC concentrations this article provides estimations of net primary production and mineralization of carbon -net carbon metabolism -in Cima Lake (Rio de Janeiro State). This is the first assessment on carbon metabolism of Cima Lake. Variations on daily net car-bon metabolism of Cima Lake are pointed out and interpreted as a clear evidence of an unstable situation in the aquatic environment. The findings are discussed as indicators of dynamic biological behavior toward production or mineralization of organic matter in the system. Additionally, in the light of our results we emphasize the axial influence of both sampling strategy and treatment of scientific data for a characterization/interpretation of aquatic systems' metabolism.
MATERIAL AND METHODS
Study area and site samplings
Cima Lake is located in the Municipality of Campos (21º46'S, 41º31'W), Rio de Janeiro State (Brazil). The lacustrine system contributes economically to the region either as a fishing source or as touristic/recreational site. It has been target of hydrobiological, geochemical and ecophysiological studies (PRO- AGRO, 1975;Huszar & Silva, 1992;Almeida, 1998;Calasans, 1998;Andrade et al., 1998;Pedrosa et al., 1999). Fluvial processes from the Quaternary period at the Holocene epoch formed the lake (Lamego, 1945). The lake is a medium (13.5 km 2 ), freshwater (< 50 µS cm -1 ), shallow (maximum depth frequently < 4.0 meters) and eutrophic phytoplankton based-system [average Chl a > 30 µg L -1 (center of the Lake)]. The water column is typically nonstratified (holomitic/polimitic lake). Macrophytes are mostly limited to the littoral zone, especially close to the mouth of Imbé and Urubu streams. The water is very soft, and there is no carbonate in the bottom sediments. Sugar cane crops, patches of secondary forest and pasture domains surround the lacustrine system. The watershed is of gneissic-granitic origin followed by Quaternary plains of sedimentary nature, and its area accounts for 710 km 2 . Imbé stream provides most (∼ 100%) of the water inflow to the lake and the lake water outflows through the Ururaí channel ( Fig. 1). Three sites were considered for the present study and their locations are presented in Fig. 1.
Sampling and analytical procedures
This study covered 36 hours with two dark periods (nights) and one light period (day) -from 5:30 p.m. to 5:30 a.m. -on March 5 th , 6 th and 7 th , 1997. The sequence of sampling followed the order: site1 → site 3 → site 2 ( Fig. 1). The mean time for concluding each set of sampling (all the three sites) was 40 minutes. The depth at sites 1, 2 and 3 was 2.8, 4.1 and 3.4 meters, respectively. Water samples were collected with a van Dorn bottle at sub surface depths (∼ 0.20 m). Polyethylene and oxygen bottles were gentle filled from the bottom, overflowing the water for at least a half of their volumes and closed with no head-space or bubble air. The former were kept in a cool and dark ambient (in an icebox) and the latter were kept immersed in water from the lake (also in an icebox) until the moment of analyses. The analyzes were performed immediately after each set of sampling. Dissolved oxygen (DO) was determined according to Winkler method (Wetzel & Likens, 1991) with a semi-automatic titration system (Hydro-Bios Kiel). Temperature and pH were measured with portable meters (thermometer and Digimed DMPH-3 pHmeter). Total alkalinity was determined through an automated acidimetric titration system (Mettler DL-21 titrator) with 0.01 N HCl as the acid solution. For every pair of consecutive samples (two consecutive samplings from an specific site) total alkalinity was averaged as suggested by Carmouze (1994). Total DIC concentrations, CO 2 % saturation and net biological activities were determined from temperature, pH, and averaged total alkalinity (as previously described) by using a set of algorithms ("CARBDO-CE", "CO 2 EQ2" and "BIOFLUX"; Carmouze, 1994). The values of wind speed used to calculate gas exchange coefficients were from the meteorological campus of the Universidade Federal Rural do Rio de Janeiro (Campos, RJ), which is ∼10 km away from the study area. For every site a total of thirteen samples (n = 13) were collected. Sample analyses were run in duplicate or triplicate and the analytical coefficient of variation was consistently lower than 5%.
RESULTS AND DISCUSSION
Metabolic status of the lake -indicators
The lake was characterized by low values of alkalinity, varying from 147 to 301 µEq L -1 ; slightly acid to neutral pH, ranging from 6.03 to 7.03; dissolved oxygen (DO) ranging from 128 to 248 µmol L -1 , and DIC varying from 203 to 773 µmol L -1 (Table 1). Water temperature varied from 27 to 29ºC (Table 1) and diurnal curve paralleled those of pH (Spearman correlation (r s ) = 0.433, n = 39, P < 0.01) and DO (r s = 0.449, n = 39, P < 0.01). The correlation between DO and pH was even more evident (r s = 0.904, n = 39, P < 0.01). These data suggest that primary productivity, or mineralization, or both, were affected by diurnal variation of temperature and light. Light availability and increased temperature are physical factors that typically may give a higher photosynthetic rate (Raven, 1994). In addition, the horizontal distribution of both DO-pH and DIC-%CO 2(aq) followed an opposite gradient of concentrations. This is expected because oxygen and carbon dioxide are, at least in part, complementary tracers of metabolic activities (Carmouze, 1994). By mineralization (e.g. bacterial respiration) water pH tend to decrease with the increase of inorganic carbon concentrations. On the other hand, phototrophic carbon dioxide fixation often lead to an increase of pH and DO as a result of oxygenic photosynthesis (Wetzel & Likens, 1991). Therefore, while DO and pH tended to increase from site 1 to site 2 and/or 3, DIC and %CO 2(aq) tended to decrease. The CO 2 saturation (%) varied greatly, from 665 to 4,901, from 385 to 1,749, and from 339 to 1,656 in sites 1, 2 and 3 respectively (Table 1). Despite these differences all values stated a condition of carbon dioxide supersaturation in the lake, which is an indication of heterotrophy or net respiration in the lake.
Carbon metabolism -variations in the lacustrine system
At first glance, DIC data suggest that heterotrophic activity was dominant in Cima Lake and, consequently, that the lacustrine system functioned as a net source of inorganic carbon. In the dark periods there was, indeed, a net production of DIC (Table 2). However, the arithmetic mean of combined periods from Table 2 [dark/light from days 5 and 6 ('combination 1'), and light/dark from days 6 and 7 ('combination 2')] showed a net primary productivity in the lake, irrespective to the site considered. Therefore, the system had a net consume of DIC from 56 (site 1) to 109 mmol m -2 day -1 (site 2), which corresponds to a production of organic carbon of 0.7 and 1.3 g C m -2 day -1 , respectively (Fig. 2). Autotrophy in the lake was also confirmed by individual combinations of dark/light ('combination 1') and light/dark ('combination 2') periods within the 36 h of study, though great differences amongst combinations were evident, especially in the sites 2 and 3 (Fig. 3). Therefore, DIC consumption extended from 53 to 59, from 25 to 194 and from 46 to 107 mmol m -2 day -1 , respectively, in sites 1, 2 and 3 (Fig. 3a). These values are equivalent to a production that ranges from 0.3 to 2.3 g C m -2 day -1 (Fig. 3b). Additionally, we might also present a single value of primary productivity for Cima Lake as a whole, as being a function of the arithmetic mean of values from combinations '1' and '2'. In this case, estimate of net primary productivity would be equal to -80 mmol DIC m -2 day -1 (or 0.96 g C m -2 day -1 synthesized). Overall, the observed differences indicate that, besides the treatment of data chosen, both spatial and temporal functions (short term in this study-case) may greatly affect the final evaluation of net carbon metabolism of Cima Lake.
Differences in daily rates of primary productivity in individual aquatic systems can, in fact, be enormous. Khondker & Kabir (1995) found pri-mary productivity between 1.6 and 6.8 g C m -2 day -1 in a mesotrophic pond in Bangladesh from an annual study. Internal comparisons of our results from individual combinations ('combination 1' and 'combination 2', Fig. 3) showed relative differences that were similar to that from Khondker & Kabir (1995). Depending on the combination ('1' or '2') relative differences in the net primary productivity ranged from a factor of ∼1.2 (site 1) to 7.8 (site 2) in Cima Lake system. It means that short-term primary productivity variations can rival those of long-term. Studying distribution of phytoplankton and photosynthesis in Lake Baringo (Kenya) Patterson & Wilson (1995) interpreted diurnal cycle as dominating over any seasonal limnological cycle in the lake.
These observations suggest that careful is need to conceive and compare mean annual values of primary productivity in aquatic systems.
Net fluxes of dissolved inorganic carbon (DIC) biologically fixed (negative values = production) or released (positive values = mineralization) per light/dark periods in Cima Lake. Light and dark periods correspond to samplings in the day and night periods, respectively. Values are presented in mmol m -2 12 h -1 . Every value is an integration from a total of four intervals of three hours each (yielding a total of 12 hours for every period).
In other words, annual estimates of primary productivity are potentially subject to great variations since they are build up from daily estimates, typically derived from a few set of measures and restricted to a short part of day. Yet, it should be kept in mind that the use of different methodologies for primary productivity calculations (e.g. 14 C, O 2 , DIC, fluorescence) may represent an additional source of variation for inter comparisons between aquatic systems (not considered here).
In aquatic systems annual primary production usually ranges from virtually 0 (no net production) to 10 3 g C m -2 . Nevertheless, in coastal lagoons primary production typically ranges from 200 to 500 g C m -2 yr -1 (Knoppers, 1994). Our data converted to annual net primary production clearly show a derivative case of short-term variation, with values ranging from a minimum of 110 to a maximum of 850 g C m -2 yr -1 . The amplitude of these values points out an unstable situation in the lacustrine system. This situation could be related to a dramatic input of 'new' waters from Imbé stream to Cima Lake because the period of sampling was preceded by a rainy week. It is supported by the fact that water level in Cima Lake raised ∼ 0.6 m in only one week (Souza, pers. commun.). In the field, however, clear sky and sunny days marked the weather. In such a situation solar radiation is abundant and nutrient is quite non-limiting to phytoplankton growth. The lake metabolism, therefore, seemed to be in a process of shifting from heterotrophic (indicated by CO 2(aq) supersaturation) to autotrophic function (evidenced by the net primary productivity). This likely explain the short-term primary productivity variation encountered in Cima Lake.
CONCLUSIONS
Our results are spatial and temporal limited because both they are site specific and the approach used here was based in a single short-term sampling. On the other hand, as sampling protocols are normally carried out in single days along the year, frequently based on monthly or biweekly frequencies, the final scientific build up and characterization of aquatic systems could be in part biased.
This is more critical if taken into account diurnal and/or daily variation, which are potentially Table 2).
greater than seasonal one, especially in tropical environments (Barbosa, 1997). Another concern is associated to spatial variation. It is relevant from a systemic point of view since aquatic systems are characterized by connected and interdependent parts, to which forms a unity of system. Thus, for a reliable understanding of lake systems we suggest that sampling protocols should take into account the site-specific characteristics rather than following a mechanical or classical sampling approach. This is especially recommended in what concern natural great variations as typically happens with metabolism and other variables-like associated to water milieu. study. FENORTE, CNPq (CER 521965/98-9) and FINEP supported this work. Fig. 3 -Like Fig. 2, but for individual combinations. 'Combination1' means combined dark/light periods from days 5 and 6, and 'Combination 2' means combined light/dark periods from days 6 and 7 on March 1997 (see Table 2). (a) Inorganic carbon flux; (b) equivalent carbon synthesized (C = organic carbon produced).
Fig. 1 -
1Composition of maps showing the geographic localization of Cima Lake (top), the watersheds (middle) -Urubu watershed is shown in dark gray while Imbé watershed is in white, Cima Lake is in black, -and the localization of sampling sites in the lacustrine system (bottom).
Fig. 2 -
2Spatial biologically mediated net flux of dissolved inorganic carbon (DIC) and its equivalence in carbon (C) synthesized (= organic carbon produced). Every value represents the arithmetic mean of dark/light and light/dark combined periods within the 36 hours of study (see text and
TABLE 1
1Mean water values of alkalinity, pH, temperature, dissolved inorganic carbon (DIC), dissolved oxygen (DO)
and carbon dioxide saturation in Cima Lake from integrated light and dark periods within the 36 hours
(n = 13) of study on March 5, 6 and 7 1997. Values between parentheses correspond to minimum and
maximum determinations.
TABLE 2
2
Acknowledgments -We thank A. A. R. Gobo, A. C. O. Pessanha and W. P. Souza for collaborative efforts related to sampling and technical support within the 36 hours of our
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| Silicon is the essential element to phytoplankton, determining the growth of phytoplankton. Phytoplankton is the basis of the marine food chain, as well as phytoplankton has tremendous capacity to absorb carbon. Phytoplankton and human determine the change of atmospheric carbon collectively, so the earth system is able to maintain the dynamic balance of the emission of anthropic carbon and the absorption of carbon by phytoplankton. This paper analyzed the effects of Silicon to the growth of phytoplankton, the absorption of CO2 by phytoplankton, the biogeochemical process of silicon, and revealed the effects of silicon to the change of phytoplankton growth and atmospheric carbon. | The effects of acidity on primary production, species composition, and abundance of phytoplankton were investigated in six lakes in the Sudbury area of Ontario, where pH values lay between 4.05 and 7.15. Significant relationships showing an increase in water transparency and decrease in chlorophyll a concentration with declining pH were found. Percentage similarity of community (PSc) and community coefficient (CC) values were highest between lakes closest in pH, reflecting progressive changes in species composition. As the pH declined, Chlorophyta diminished in importance and the Cyanophyta became dominant. The phytoplankton diversity index (DI) remained relatively unchanged between pH values of 7.0 to 5.0 but decreased at lower values. Primary production in milligrams C metre−3 hour−1 was reduced in lakes below pH 5.5; however, as a result of the increase in depth of euphotic zone accompanying more acidic conditions, primary production in milligrams C metre−2 hour−1 remained high down to pH 4.4, below wh... | A model of carbon isotope discrimination by phytoplankton was developed which took into account the occurrence of a carbon-concentrating mechanism (CCM). A simple equation was obtained for the model involving CO2 active transport. In the case of HCO3~ active transport, another equation was developed based on a series of approximation s. The former equation was used to analyse reported and newly obtained data from culture experiments and field observations in both freshwater and marine environments. In most cases, a linear relationship between a combined para- meter, (1 -/)Ci, which was made up of the relative contribution of active CO2 uptake to total carbon uptake (/) and the intracellular CO2 concentration (Ci), and CO2 concentration in bulk solution (Ce) was obtained as (1 -/)Ci = aCe - b, with a high correlation coefficient (r2 > 0.9). The slope a is sug- gested as a measure of the ratio of diffusive to total (diffusive + active) CO2 transport, while b/a rep- resents CO2 demand. |
Introduction
Organic matter in the ocean is one of the largest dynamic carbon reservoirs on Earth that interacts with atmospheric CO 2 concentrations on time scales of 1000 to 10 000 years (Hedges, 1992). Biological consumption of CO 2 during photosynthesis and the related production of organic matter are Correspondence to: J. Piontek ([email protected]) counteracted by CO 2 -regenerating processes with bacterial respiration being the predominant one (Rivkin and Legendre, 2001). About 75-95% of organic matter produced by autotrophic organisms gets remineralized by heterotrophic bacterioplankton in the surface ocean (Martin et al., 1987;Boyd et al., 1999), the zone that is most strongly affected by ocean acidification (Raven et al., 2005). Equilibration of seawater with rising CO 2 in the atmosphere has already lowered the ocean pH by 0.12 units compared to pre-industrial values, which in turn has increased the concentration of hydrogen ions by 30% (Houghton et al., 2001;Sabine et al., 2004;Raven et al., 2005). Effects of ocean acidification on bacterial metabolism and activity are currently largely unexplored but of utmost importance for accurate estimates of organic matter cycling and the carbon balance in the future ocean.
Polysaccharides are a major component of marine organic matter and comprise up to 15% of sinking and suspended particulate organic carbon (Tanoue and Handa, 1987;Bhosle et al., 1992;Hernes et al., 1996) and up to 32% of dissolved organic carbon (DOC) (Pakulski and Benner, 1994). They can account for more than 50% of total phytoplankton primary production (Baines and Pace, 1991) and provide a labile energy and carbon source to heterotrophic bacterioplankton in form of structural cell components, storage glucan, and phytoplankton exudates. The bacterial degradation of highmolecular-weight organic compounds like polysaccharides is initiated by the activity of extracellular enzymes (Hoppe et al., 1988;Chróst, 1991). Thereby, macromolecules are enzymatically hydrolyzed outside of bacterial cells into units of low molecular weight that are small enough to be transported across the cytoplasmic membrane. Extracellular α-and β-glucosidase released by bacterioplankton cleave α-and β-glycosidic bonds in polysaccharides, respectively, and generate glucose monomers that can be assimilated by bacterioplankton and fuel its heterotrophic metabolism (Chróst, 1991). It is well-known that the pH is an important factor regulating the velocity of enzymatic reactions (Arrhenius, 1889;Tipton and Dixon, 1979). Changing concentrations of hydrogen ions in the enzyme's environment alter the ionization state of amino acids, and thus affect the three-dimensional protein structure of the active site. Enzymatic reactions exhibit a specific narrow range of pH, where highest reaction velocity is apparent, but already small deviations from this pH optimum result in decreased enzymatic rates. In contrast to intracellular enzymes, acting in the cell's buffered cytoplasm, extracellular enzymes directly experience the pH of the outer environment. Also the activity of extracellular enzymes in aquatic environments was shown to respond sensitive to changing pH. Rates of bacterial extracellular glucosidases of a freshwater lake and in marine sediments varied considerably when pH modifications were carried out during in vitro experiments (King, 1986;Chróst, 1991;Münster, 1991). Today, it is not known how ocean acidification will affect the degradation activity of marine bacteria, and the microbial turnover of organic matter. Here, we investigated the effect of lowered seawater pH simulating ocean acidification on the rate of enzymatic polysaccharide hydrolysis in natural bacterioplankton communities. Our study included laboratory experiments with organic matter derived from monospecific cultures of the bloom-forming coccolithophore Emiliania huxleyi, as well as field assays conducted at the Bay of Biscay (North Atlantic). Degradation of polysaccharides was followed under present-day pH (7.9-8.3) and under pH lowered by 0.2-0.3 units as expected for the ocean within the next 100 years (Houghton et al., 2001;Caldeira and Wickett, 2003;Raven et al., 2005).
Materials and methods
Experimental setup
In current marine research, the biological response to elevated seawater pCO 2 and biogeochemical consequences are mainly investigated by perturbation experiments, in which different approaches are used to manipulate the seawater carbonate chemistry (Gattuso and Lavigne, 2009). In our experiments, reference incubations representing present-day pH conditions were compared with acidified incubations that exhibited pH values projected for the future ocean. Manipulation was carried out by both CO 2 aeration and acid addition to exclude impact of the manipulation mode. The pH was measured using a combined temperature-and pH-probe (WTW 340i) calibrated with standard buffer solutions of pH 4.006, 6.865, and 9.180 (WTW standard DIN/NBS buffers PL 4, 7, and 9). To examine the effect of acidification on the bacterial degradation of polysaccharides we conducted two culture experiments (CultExp I, II) and two field assays (FieldAssay I, II). Different setups with regard to nutrient supply, light regime, and plankton communities were applied to include variability of important abiotic and biotic factors in marine pelagic ecosystems. The experimental designs are described below and summarized in Table 1. CultExp I: Here, incubations simulating future-ocean conditions were initially but not continuously acidified with pure CO 2 gas. Thereby, the initial seawater pH of the future-ocean treatment was adjusted to 7.8 before phytoplankton growth started. This target pH corresponded to 750 µatm CO 2 as calculated by the use of the program CO 2 sys (Lewis and Wallace, 1998) after measurement of the initial total alkalinity by the Gran electrotitration method (Gran, 1952). Seawater carbonate chemistry was not experimentally modified in the present-day treatment. The pH of both present-day and future-ocean treatment increased during phytoplankton growth and declined during dark incubation and bacterial degradation of the phytoplankton-derived organic matter. During the degradation phase, the mean pH was 8.3 and 8.1 in the present-day and the future-ocean treatment, respectively.
Organic matter was derived from biomass and exudates of the coccolithophore Emiliania huxleyi. Batch cultures of E. huxleyi (strain PML B92/11) were grown in sterile-filtered seawater enriched with 50 µmol l −1 nitrate and 3 µmol l −1 phosphate, applying a 16/8 h light/dark cycle and a photon flux density of 200 µmol photons m −2 s −1 . Culture-derived organic matter was inoculated with a natural bacterioplankton community collected at the North Sea after 27 days, when decreasing growth rates of E. huxleyi indicated exhaustion of inorganic nutrients. Incubations were conducted in 10 l-Nalgene bottles kept in permanent dark for 30 days after the addition of the bacterioplankton inoculum. The bottles were mixed carefully, but thoroughly twice a day and prior to samplings. Incubation at present-day and future-ocean pH was conducted in duplicate at 14 • C.
CultExp II: Permanent aeration with CO 2 -air-mixtures containing 550 µatm and 900 µatm CO 2 led to constant pH values of 7.9 and 7.7 during phytoplankton growth and organic matter degradation in the present-day and future-ocean treatment, respectively.
Organic matter was derived from continuous cultures of E. huxleyi (strain PML B92/11) that were supplied with sterile-filtered seawater containing 30 µmol l −1 nitrate and 1 µmol l −1 phosphate at a dilution rate of 0.1 d −1 . A 16/8 h light/dark cycle and a photon flux density of 300 µmol photons m −2 s −1 were applied during growth of E. huxleyi. The cultures were grown for 12 days before the bacterial inoculum was added. After inoculation with bacteria, the flow-through was stopped and incubations were kept in permanent dark at 14 • C for 13 days.
FieldAssay I: A field sample collected at the Bay of Biscay (47 • 07 83 N, 6 • 92 01 E, North Atlantic) in May 2007 was subdivided into incubations at present-day and futureocean pH. Incubations of the future-ocean treatment were acidified with 0.1 M hydrochloric acid. The pH was lowered by 0.3 units to 7.9 by acid addition. Due to low concentrations of organic matter and consequently low bacterial degradation activity the pH remained constant until the end of dark incubation although no further acid addition was carried out.
The surface samples included the in situ assemblages of phyto-and bacterioplankton. The phytoplankton community was dominated by coccolithophores. Organic matter degradation was conducted in 10 l-Nalgene bottles in permanent dark. Incubations were run in triplicate close to in situ temperature at present-day and at future-ocean pH for 12 days.
FieldAssay II: Like in FieldAssay I, surface samples were collected at the Bay of Biscay (47 • 05 34 N, 7 • 16 63 E, June 2006). Aeration with CO 2 -air-mixtures of 380 µatm and 750 µatm CO 2 generated constant pH values of 7.9 and 7.6 in the present-day and future-ocean treatment, respectively.
The surface sample was subdivided into duplicate incubations at present-day and future-ocean pH and incubated in a chemostat system. A 16/8 h light/dark cycle and a photon flux density of 200 µmol photons m −2 s −1 were applied during the whole incubation time of 8 days. Incubations were supplied with 20 µmol l −1 nitrate and 1.8 µmol l −1 phosphate in filtered seawater of the sampling site. A flow rate of 0.13 d −1 was applied. Hence, in contrast to the other experiments described above, autotrophic production and bacterial degradation of organic matter occurred simultaneously at steady state. The chemostat was run for 8 days prior to sampling.
Analytical methods
The analysis of polysaccharides was conducted by High Performance Anion Exchange Chromatography (HPAEC) coupled with Pulsed Amperometric Detection (PAD) on a Dionex ICS 3000. Concentrations of dissolved and particulate combined glucose, galactose, arabinose, mannose, xylose, fucose, rhamnose, glucuronic acid, and galacturonic acid were detected. The sum concentration is referred to as total polysaccharides. Only polysaccharides >1 kDa were analyzed, since this fraction requires cleavage by extracellular glucosidases prior to bacterial metabolization. Polysaccharides <1 kDa, oligosaccharides, and monosaccharides were separated prior to analysis by the use of a 1 kDa dialysis membrane during desalination of the seawater sample. After that, samples were hydrolyzed with hydrochloric acid at a final concentration of 0.8 M for 20 h at 100 • C.
Samples for particulate organic carbon (POC) were filtered onto precombusted glass fibre filters (GF/F, Whatman). Filters were acidified with 0.2 M hydrochloric acid to remove all particulate inorganic carbon. After drying, concentrations of POC were determined with an elemental analyzer (Eu-roEA, Euro Vector).
Activities of extracellular enzymes were determined by the use of fluorogenic substrate analogues (Hoppe, 1983).
The activities of α-glucosidase and β-glucosidase were estimated from the enzymatic hydrolysis of 4-methylumbelliferyl-α-glucopyranoside and 4-methylumbelliferyl-β-glucopyranoside, respectively. Samples were incubated at in situ temperature for 3 to 5 h with fluorogenic substrates added to a final concentration of 1 µmol l −1 in all experiments. The concentration of 1 µmol l −1 substrate analogue corresponds to the magnitude of natural polysaccharide concentration in the ocean (Myklestad and Børsheim, 2007). The fluorescence emitted by 4-methylumbelliferone (MUF) molecules was detected at 355 nm excitation and 460 nm emission wavelength, using a plate reader (FLUOstar OPTIMA, BMG Labtech, and Fluoroskan Ascent, Thermo Labsystems) or a cuvette fluorometer (F-2000, Hitachi). Calibration was carried out with solutions of MUF. In order to consider pH effects on the fluorescence intensity of MUF, standard solutions were adjusted to pH 7.6, 7.8, 8.0, 8.2, and 8.3, buffered with 1% 3-(N-Morpholino)-propanesulfonic acid. The activities of α-glucosidase purified from Bacillus staerothermophilus (Sigma) was calculated from the turnover time of 50 µmol l −1 4-methylumbelliferyl-α-glucopyranoside in 1 mM n-2-hydroxyethylpiperazone-n-2-ethanesulfonic acid adjusted to pH 7.55, 7.70, 7.90, and 8.10. Fluorescence was measured in time intervals of 5 min for 2 h using a plate reader (FLUOstar OPTIMA, BMG Labtech).
Bacterial cell numbers were determined by flow cytometry (FACSCalibur, Becton Dickinson) in both culture experiments and in FieldAssay I. Nucleic acid was stained with SybrGreen I (Invitrogen). Bacterial abundances were estimated after visual inspection and manual gating of the bacterial subpopulation in the side scatter vs. green fluorescencecell cytogram. Yellow-green fluorescent latex beads (diameter 0.94 µm, Polyscience) were used to normalize the counted events to a reference volume. TruCount beads (Becton Dickinson) were used for daily intercalibration and absolute volume calculation (Gasol and del Giorgio, 2000). In FieldAssay II, bacterial cells were counted by epifluorescence microscopy. For this purpose, samples were filtered onto black 0.2 µm polycarbonate filters and stained with 4 ,6-diamidino-2-phenylindole (DAPI) (Porter and Feig, 1980). Bacterial abundances were calculated from cell counts of 10 randomly selected fields per filter that contained at least 100 cells each.
Data analysis
The losses of polysaccharides and POC were calculated by subtracting the final from the initial concentrations. Data on polysaccharide loss (n=4) and glucosidase activity (n=5) of CultExp I, CultExp II, and FieldAssay I were compiled for statistical analysis. Differences between reference and acidified treatment were tested by means of paired t-test. Statistical significance was accepted for p<0.05. Linear regression was performed using the software package SigmaPlot 9.0 (SysStat).
Results
The bacterial degradation of polysaccharides in CultExp I, CultExp II, and FieldAssay I was assessed from the loss of polysaccharides during dark incubation. The loss of total polysaccharides, including dissolved and particulate sugars >1 kDa, was significantly higher at lowered pH than in the reference incubations representing present-day conditions (p=0.005) (Fig. 1). At the end of the degradation experiments, the loss of combined glucose, the dominating sugar in polysaccharides, was up to 32% higher in futureocean treatments, and the loss of total polysaccharides, including seven neutral sugars and two uronic acids, was higher by 26%. In CultExp I and CultExp II, experiments conducted with organic matter freshly produced by E. huxleyi, the higher loss of polysaccharides at lowered pH coincided with a higher loss of POC (Fig. 1). In FieldAssay II, a natural plankton community was sampled from surface waters at the Bay of Biscay and incubated in a chemostat system (Table 1). Because a light/dark cycle was applied and a low but constant nutrient supply was provided during this experiment, concentrations of polysaccharides and POC are the net result of phytoplankton production and of simultaneous bacterial degradation. Nevertheless, final concentrations of combined glucose, total polysaccharides, and POC were reduced by 46%, 37%, and 29% respectively, in acidified incubations compared to the present-day reference. It has been shown before that production of polysaccharides by marine phytoplankton increases with pCO 2 as a result of higher photosynthesis rates (Engel, 2002;Rost et al., 2003). Hence, lower concentrations of polysaccharides under elevated pCO 2 point to an in culture experiments and field assays. Glucosidase activity at future-ocean pH was significantly higher than at present-day pH (paired t-test, p<0.01). Glucosidase rates of Cult-Exp I, CultExp II, FieldAssay I, and FieldAssay II were compiled for the statistical test. (b) Log-log plot of cell-specific α-and βglucosidase activity (circles and triangles, respectively) at presentday versus future-ocean pH.
accelerated bacterial degradation that counter-steered phytoplankton production (Fig. 1). The degradation of marine organic matter is driven by the hydrolytic activity of extracellular enzymes, which are predominately produced by bacteria. In our experiments, activities of extracellular α-and β-glucosidase were determined to assess rates of enzymatic polysaccharide hydrolysis. Extracellular glucosidase activity was significantly higher at future-ocean pH than at present-day pH (p<0.01) in all experiments (Fig. 2a). Higher enzymatic activities were not induced by differences in bacterial cell abundances, since bacterial cell numbers of all experiments did not reveal significant differences between the two pH treatments (p=0.38; data not shown). Hence, also cell-specific glucosidase rates at lowered seawater pH clearly exceeded those at present-day pH (Fig. 2b).
In our experiments, seawater pCO 2 was increased to simulate future-ocean conditions. Elevated pCO 2 levels corresponded to different pH values in the four experiments, ranging from 7.6 to 8.1. From the difference in pH between present-day and future-ocean treatment the increase in proton concentration induced by experimental manipulation was calculated for the four experiments (Table 1). This allowed us to relate the difference in glucosidase activity between present-day and future-ocean treatment to the increase in hydrogen ion concentration induced by acidification. The synthesis of all experiments revealed that the observed increase in glucosidase activity was directly proportional to the increasing acidity of seawater (r 2 =0.80, p<0.01) (Fig. 3). Changes in glucosidase activities as inferred from our experiments reflect a community response of bacterioplankton to simulated acidification. In addition, we tested the response of purified α-glucosidase that was isolated from Bacillus stearothermophilus to decreasing seawater pH. B. stearothermophilus is a generalist bacterium that is widely distributed in ocean sediments and at marine vents (Sharp et al., 1992;Maugeri et al., 2002). Exposed to the same range of acidification, the increase of this specific α-glucosidase activity was in the same order of magnitude as that of the natural glucosidase assemblages (Fig. 3). This similarity in pH sensitivity of natural glucosidase assemblages and of an isolated bacterial α-glucosidase (Fig. 3), together with increased cellspecific glucosidase rates at lowered seawater pH (Fig. 2) strongly suggest that the velocity of enzymatic polysaccharide hydrolysis in our experiments was directly affected by changes in seawater pH.
Discussion
The pH is known as an important regulating factor for bacterial extracellular enzyme activity in aquatic environments (Chróst, 1991), but potential impacts of ocean acidification on bacterial degradation activity are only poorly investigated. In previous experimental studies, large pH ranges with large intervals were applied to characterize enzyme assemblages of selected aquatic ecosystems biochemically (King, 1986;Chróst, 1991;Münster, 1991). Results from these studies are not sufficient to answer questions concerning effects of current and expected future ocean acidification that is characterized by rather small pH changes on large spatial scales. So far, potential effects of ocean acidification on marine bacterioplankton were tested only by two studies that investigated bacterial growth and activity during the development of phytoplankton blooms under different seawater pCO 2 in mesocosms (Grossart et al., 2006;Allgaier et al., 2008). Grossart et al. (2006) showed higher rates of bacterial extracellular protease activity and a higher cell-specific bacterial biomass production during the phytoplankton bloom at elevated pCO 2 . In contrast, Allgaier et al. (2008) did not find differences in bacterial biomass production and carbon demand between the different pCO 2 treatments. The experimental design of both mesocosm studies, however, did not allow to distinguish direct pCO 2 -and pH-effects on bacterioplankton activity from effects induced by CO 2 -related changes in algal organic matter production (Engel et al., 2004;Egge et al., 2009). Primary production and phytoplankton exudation were highest in mesocosms of elevated pCO 2 , so that the supply of labile substrates was enhanced and likely affected bacterial activity. Our experiments suggest that small pH decreases of 0.2 to 0.3 units, corresponding to the near-future seawater pCO 2 , had a direct effect on the physicochemical control of natural extracellular glucosidase assemblages in marine pelagic ecosystems (Figs. 2 and 3). Extracellular glucosidase activity increased directly in response to rising proton concentration in our experiments (Fig. 3). The experimental results also show that rates of polysaccharide hydrolysis by marine glucosidase assemblages are not at their maximum at present-day seawater pH. This interpretation is in good accordance with previous studies conducted in aquatic environments, where optima for extracellular enzymes in freshwater and marine sediments did not correspond to in situ pH values (King, 1986;Münster, 1991). Hence, ocean acidification may shift seawater pH closer towards the optimum value of marine glucosidase activity.
Effects of acidification on polysaccharide and carbon degradation
Polysaccharides are a major component of reactive organic matter in the ocean as indicated by sharply declining concentrations in the subsurface layer (Kaiser and Benner, 2009). The hydrolytic activity of extracellular enzymes accomplishes the initial step in bacterial organic matter degradation (Chróst, 1991;Hoppe, 1991), and drives the solubilization of organic particles (Smith et al., 1992;Hoppe et al., 1993). Higher rates of extracellular glucosidases at lowered seawater pH significantly accelerated the degradation of polysaccharides in our simulation experiments (Figs. 1-3). Therefore, experimental results strongly suggest that the impact of ocean acidification on the reaction velocity of extracellular enzymes will be strong enough to affect early stages in the diagenetic processing of organic matter. In culture experiments, acidification did not only accelerate polysaccharide degradation but also enhanced the loss of POC (Fig. 1), which can be explained by the large polysaccharide fraction of freshly produced particulate organic matter. In the ocean, high polysaccharide yields in organic matter often coincide with high production of algal biomass and exudates during phytoplankton blooms (Baines and Pace, 1991;Handa et al., 1992;Engel et al., 2002). Hence, when bacterial activity increases during the decline of phytoplankton blooms, lowered seawater pH might exert substantial influence on the overall turnover of organic carbon in the ocean. Since the penetration depth of anthropogenic CO 2 in the ocean and related changes in seawater pH extend up to several hundred meters depth (Caldeira and Wickett, 2003;Sabine et al., 2004), freshly produced organic particles sinking out of the surface ocean may also become subject to an accelerated degradation in the twilight zone (100-1000 m depth), where intense bacterial activity strongly attenuates material fluxes to the deep ocean (Martin et al., 1987;Smith et al., 1992).
Effects of increasing glucosidase activity at lowered seawater pH on bacterial carbon acquisition and growth
The activity of extracellular enzymes largely determines the supply of low molecular weight substrates for direct bacterial uptake (Chróst, 1991). Among the great diversity of organic carbon compounds in the ocean, free glucose monomers must be considered as main carbon and energy source for bacterial growth (Rich et al., 1996). Concentrations of glucose monosaccharides in the ocean are usually below 100 nmol l −1 , but high glucose uptake rate constants reveal high fluxes and underscore the importance of glucose as substrate for the bacterial metabolism (Rich et al., 1996;Skoog et al., 2002). The enhanced enzymatic hydrolysis of polysaccharides induced by lowered seawater pH in our experiments increased the availability of glucose for bacterial uptake and thus improved the bacterial carbon supply. The fate of glucose monomers taken up by bacterioplankton depends on the nutrient availability and the physiological state of the bacterial cell. Up to 60% of glucose consumed by marine bacterioplankton gets remineralized by respiration in nutrient-poor regions (Rich et al., 1996;Bianchi et al., 1998). The proportion of respired glucose is significantly lower in nutrient-rich areas, where appropriate nitrogen and phosphorous sources fulfil bacterial growth demands (Bianchi et al., 1998). In order to balance an increased availability of labile carbon, bacteria are able to utilize inorganic nitrogen (Kirchman et al., 1990;Kirchman, 2000). In particular actively growing marine bacteria act as sink for inorganic nitrogen, when an easily utilizable carbon source like glucose is available (Goldman and Dennett, 1991). The increased bacterial consumption of inorganic nutrients in response to increasing labile carbon availability changes the partitioning of inorganic nutrients between bacterioplankton and phytoplankton and leads to lower phytoplankton biomass production (Thingstad et al., 2008). Hence, it must be assumed that also increased glucose availability resulting from enhanced glucosidase activity at lowered seawater pH can stimulate bacterial competition for mineral nutrients and can mediate secondary effects on autotrophic production in the ocean. With respect to ocean acidification, the acclimation and adaptation potential of organisms on the species-and community-level must be taken into account. However, the capability of single species and natural assemblages, including bacterioplankton, to adapt to changing seawater carbonate chemistry is poorly investigated. Therefore, the impact that potential acclimation and adaptation of key species and marine communities would have on biogeochemical processes in the future ocean is unclear. This study is focused on polysaccharide degradation in marine systems that is driven by highly diverse bacterial communities. Experiments included natural glucosidase assemblages derived from bacterioplankton communities of different oceanic sites. Therefore, experimental results suggest that increased glucosidase activity at lowered seawater pH does not depend on the abundance of some specific bacterial strains, but reflects a community response to lowered seawater pH. Furthermore, the accelerated enzymatic polysaccharide hydrolysis represents a biochemical pH effect. The elevated proton concentration in acidified incubations likely interacted with the three-dimensional protein structure of extracellular glucosidases. Acidification shifted the in situ pH to a value more favourable for marine glucosidase activity and led to an improved supply of labile substrates to bacterioplankton. Hence, higher glucosidase rates at lowered seawater pH are a chemical acidification effect on natural enzyme assemblages that is beneficial for the bacterial metabolism. Therefore, one might expect that acclimation or adaptation of bacterioplankton communities will not counter enhanced polysaccharide degradation in the future ocean.
Implications for carbon cycling in the future ocean
Heterotrophic bacteria are the main producers of CO 2 in the ocean, drive organic matter turnover, and sustain food webs (Pomeroy, 1974;Azam, 1998;Karl et al., 2003). Despite these key roles in biogeochemical cycles and ecosystem functioning, the effects of current and future changes in seawater carbonate chemistry on marine bacteria are largely unknown. Here, we showed that a decrease in seawater pH as expected for the near future increases enzymatic hydrolysis rates of polysaccharides and accelerates the bacterial degradation of organic carbon. Extrapolating results of CO 2perturbation experiments to large scales bears considerable uncertainties. Simulation experiments investigate acidification effects on biological processes isolated from complex natural systems. Nevertheless, implications of experimental studies are essential to identify feedback mechanisms of marine biological processes to rising CO 2 . If our results are representative for the ocean, ocean acidification will accelerate the degradation of polysaccharides and organic carbon on large spatial scales and may affect the vertical carbon export. The export of organic carbon from the surface to the deeper ocean, referred to as biological carbon pump (Volk and Hoffert, 1985), sustains a vertical gradient of dissolved inorganic carbon that in turn drives the ocean's uptake of atmospheric CO 2 . In the ocean, the flux of sinking organic carbon is strongly reduced by the activity of extracellular enzymes solubilising organic particles in the surface layer and in the mesopelagic zone (Smith et al., 1992). Therefore, an enhanced degradation of particulate polysaccharides at lowered seawater pH may reduce the sinking flux of organic carbon, as it accelerates the dissolution of organic particles and favours the bacterial uptake of DOC. Large-scale implications are supported by field observations from the Sargasso Sea over the last decade. Here, a doubling of the mesopelagic POC flux attenuation was determined between 1996 and 2007, when ocean acidification progressed. The increased loss of organic matter in the mesopelagic zone of the Sargasso Sea is attributed to changes in metabolic activity that, however, could not be specified (Lomas et al., 2009). Based on our findings, it can be assumed that the amount of exported polysaccharide-derived carbon was curtailed due to increasing extracellular glucosidase activity at decreasing seawater pH. Thus, increased rates of enzymatic organic matter hydrolysis could at least partly explain the increased POC flux attenuation observed at the Sargasso Sea. A large proportion of organic matter in the ocean is produced in dissolved form. DOC includes high yields of polysaccharides and can be exported to the deeper ocean by convective mixing (Carlson et al., 1994;Goldberg et al., 2009). Enhanced bacterial glucosidase activity in the future ocean may also reduce the export of DOC due to an accelerated hydrolysis of dissolved polysaccharides and a rapid bacterial assimilation of the labile hydrolysates.
In addition to effects on carbon export, the enhanced enzymatic polysaccharide degradation at lowered seawater pH may also increase the respiratory production of CO 2 in the future ocean. Higher rates of polysaccharide hydrolysis would improve the glucose availability for heterotrophic bacteria and may increase their respiratory activity. Increased bacterial respiration would establish independently from enhanced autotrophic production and therefore has the potential to disturb the metabolic balance of the sea for the benefit of net heterotrophy (Karl et al., 2003).
Both less export of polysaccharides and increased respiratory CO 2 production at lowered seawater pH have the potential to reduce the ocean's ability to absorb CO 2 from the atmosphere. In the future ocean, the accelerated organic carbon turnover by heterotrophic bacterioplankton will interact with other CO 2 -and pH-effects on the marine biota. For instance, the draw-down of inorganic carbon by phytoplankton was shown to increase under elevated seawater CO 2 (Engel, 2002;Rost et al., 2003;Engel et al., 2004;Riebesell et al., 2007). Hence, the accelerated bacterial carbon turnover may coincide with an enhanced autotrophic production of organic matter in the future ocean. Elevated seawater pCO 2 led to a higher phytoplankton production of transparent exopolymer particles that are rich in polysaccharides. Therefore, organic matter produced at high seawater CO 2 should be particularly prone to increased glucosidase activity at lowered pH. This interaction between phytoplankton production and bacterial degradation at changing seawater chemistry is an example for the complexity of acidification effects in the ocean. Complex interactions and unexplored effects of changing seawater carbonate chemistry on important biological processes make it impossible to predict the prevailing feedback of the marine biota to rising CO 2 to at the current state of knowledge.
Outlook
In the face of rapidly changing marine ecosystems, a better understanding of acidification effects on the metabolism and physiology of marine organisms and on biogeochemical cycles becomes a matter of urgency. Here, bacterial extracellular enzymes, which play a decisive role in the turnover of marine organic matter (Azam, 1998;Azam and Malfatti, 2007), were identified as pH-sensitive keystone. Since enzymes catalyze biochemical reactions in all life forms, it can be assumed that effects of decreasing pH on enzymatic activities will impact a variety of biological processes in the future ocean and evoke consequences of unprecedented complexity. For example, it has been shown that enzymes in muscle tissues of fish will respond to ocean acidification (Michaelidis et al., 2007), same as enzymes involved in growth and carbon acquisition of phytoplankton species (Hansen et al., 2007). Like in this study, results were obtained from manipulative laboratory experiments that provide a valuable tool to investigate potential consequences of lowered seawater pH on specific biological and biogeochemical processes. As an alternative scientific approach, natural pH gradients in the ocean, for example induced by marine CO 2 vents, can be used to investigate ocean acidification on the ecosystem level and can serve as validation for findings from in vitro perturbation experiments (Hall-Spencer et al., 2008). With regard to acidification effects on enzymatic reactions, in situ studies along natural pH gradients could provide insights into the interaction of different enzymatic reactions at changing rate and could evaluate potential effects on ecosystem processes.
Figure 1
1Figure 1
specific glucosidase activity (present-day pH) [amol cell -1 d -1 ] cell-specific glucosidase activity (future-ocean pH)
Fig. 2 .
2Extracellular glucosidase activity at present-day and futureocean pH. (a) Extracellular glucosidase activity in reference incubations (open bars, PD: present-day pH) and at lowerd pH (solid bars, FO: future-ocean pH)
Figure 3
Fig. 3 .
3Changing activity of extracellular glucosidases in response to rising hydrogen ion concentrations. Relative changes in glucosidase activity (C A ) of natural bacterioplankton communities (circles) and of Bacillus stearothermophilus (diamonds) were calculated according to C A =(A FO −A PD )/A PD , where A PD and A FO are the glucosidase activities at present-day and future-ocean pH, respectively. The increase in hydrogen ion concentration ( hydrogen ions) induced by experimental acidification was calculated from the difference in pH between the present-day and the future-ocean treatment. Dashed lines represent linear regressions (marine glucosidase activity: r 2 =0.80, p<0.01; α-glucosidase B. stearothermophilus : r 2 =0.96, p<0.01).
Table 1 .
1Setup of culture experiments (CultExp I, CultExp II) and field assays (FieldAssay I, FieldAssay II). Initial bacterial cell numbers and concentrations of POC are given as mean values ± standard deviation. 2 For FieldAssay I, one field sample was initially subdivided into acidified and non-acidified replicates.Experiment
phytoplankton bacterioplankton
CO 2
pH
Samplings
Incubation
T
Initial
Initial
manipulation PD
FO
Mode
Period [ • C]
Bacteria 1
POC 1
( H + , nmol l −1 )
[×10 6 cells ml −1
]
[µM]
CultExp I
E. huxleyi
natural community aeration
8.3
8.1
5
batch
30 days
14
21.4±5.3
522±168
(PML B92/11) North Sea
( 2.93)
CultExp II
E. huxleyi
natural community aeration
7.9
7.7
8
batch
13 days
15
4.9±1.8
840±86
(PML B92/11) North Sea
( 7.36)
FieldAssay I
natural community
dilute
8.2
7.9
5
batch
12 days
10
0.08 2
14 2
Gulf of Biscay, 2007
hydrochloric
( 6.27)
acid
FieldAssay II
natural community
aeration
7.9
7.6
1
chemostat
8 days
16
6.2±2.5
48±12
Gulf of Biscay, 2006
( 12.53)
PD: present-day treatment; FO: future-ocean treatment; POC: particulate organic carbon
1
Fig. 1. Degradation of polysaccharides and organic carbon at present-day and future-ocean pH. Combined glucose (>1 kDa), polysaccharides (>1 kDa), and Particulate Organic Carbon (POC) were determined in reference incubations (open bars, PD: presentday pH) and at lowered seawater pH (solid bars, FO: future-ocean pH). In FieldAssay I, samples from replicate incubations were pooled for analysis. For the experiments CultExp I, CultExp II, and FieldAssay I, losses were calculated by subtracting the residual from the initial concentration (n.d.: no loss detectable). Significance of differences between the pH treatments was assessed by means of paired t-tests (combined glucose: p=0.026; polysaccharides: p=0.005). Data of CultExp I, CultExp II, and FieldAssay I were compiled for statistical tests. For the chemostat experiment FieldAssay II concentrations under steady state conditions are given. Error bars denote the standard deviation from replicate incubations.FieldAssay I
CultExp II
FieldAssay II
www.biogeosciences.net/7/1615/2010/ Biogeosciences, 7, 1615-1624, 2010
Biogeosciences, 7, 1615Biogeosciences, 7, -1624Biogeosciences, 7, , 2010 www.biogeosciences.net/7/1615/2010/
Acknowledgements. This study was supported by the Helmholtz Association (HZ-NG-102) and the Belgian Science Policy (SD/CS/03). Many thanks are due to the crew of the RV Belgica for help during experimental work on board. This work is a contribution to the European Project on Ocean Acidification (EPOCA). Two anonymous referees are acknowledged for their suggestions on improving this publication.Edited by: S. Pantoja
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| In October and November 1988, measurements of oxygen and total dissolved inorganic carbon (TCO2) concentrations were made in the northwestern Weddell Sea to the south and north of the marginal ice edge, in order to estimate the relative importance, regarding their variations, of both biological (photosynthesis and respiration) and physical (transport of O2 and CO2 by turbulent movements and by intrusion from the atmosphere) processes. In the ice-covered region, both respiration and upwelling determined the O2 and TCO2 variations, whilst in the open water just north of the marginal ice edge, photosynthetic activity was the most important factor controlling O2 and TCO2 levels. These findings underline the importance of the activity of the pelagic ecosystem in determining the concentration of O2 and CO2 not only in the ice-free but also in the ice-covered Antarctic Ocean. | 1. Lake 302S in the Experimental Lakes Area of Canada was acidified from pH 6.7 (1981) to 5.1 (1986). The pH was further reduced to 4.5 in 1987 and held at that level until 1991. From 1992 to 1995, the pH was allowed to increase to a target value of 5.8. ::: ::: ::: ::: 2. The response of the phytoplankton community to decreasing pH from 6.0 to 5.1 was similar to that observed in another experimentally acidified lake (223) and in other atmospherically acidified lakes. Acidification affected species diversity of both the phytoplankton and epilithon. Phytoplankton diversity was positively correlated with pH. Epilithic algal diversity was more variable and did not correlate with pH. ::: ::: ::: ::: 3. Phytoplankton biomass was enhanced by acidification as the assemblage shifted from a dominance of chrysophytes to large dinoflagellates (Gymnodinium sp. and Peridinium inconspicuum). Epilithon biomass was unaffected, but dominance shifted from filamentous cyanophytes (Lyngbya) to acidophilic diatoms (Tabellaria quadriseptata and Anomoeonis brachysira). ::: ::: ::: ::: 4. The only taxon to be similarly affected in both the phytoplankton and epilithon was the cyanobacteria, being significantly reduced below pH 5.1. During early recovery (pH 5.5–5.8), cyanobacteria increased and species present prior to acidification recolonized both habitats. ::: ::: ::: ::: 5. In the early stages of recovery, planktonic and benthic assemblages remained more similar to acidified than natural assemblages, but more profound change began at pH > 5.5. | The dynamic of phytoplankton in Lake Dejguny was investigated in relation to the environmental conditions influencing water quality. The phytoplankton biomass and chlorophyll concentration in water were relatively low (typical of mesotrophic lakes), with a decreasing tendency when the water transparency significantly increased. The phytoplankton was not significantly correlated with the content of nutrients in water. The vast majority of phosphorus was in a form unavailable to phytoplankton, and the TN:TP ratio evidenced the role of nitrogen and phosphorus in colimitation of its development. The general evaluation of trophy based on TSI and TLI indicated meso-eutrophy or even slight eutrophy, because of partial assessments: TSITP, TLITP, and TLITN and domination of filamentous blue-green algae, which revealed a more advanced degree of eutrophication. | 1,999,733 |
Human activity causes a wide range of stresses of various scales in ecosystems 1 . Many scientific studies have assessed the impact of many of these stresses on aquatic ecosystems, which led to important basic knowledge in the field of limnology and ecology. Eutrophication and acidification 2 are considered to be the main processes determining trophic changes in many freshwater ecosystems. Recently, there is a growing understanding of the need to determine the combined effects of multiple factors [3][4][5] , since the widespread occurrence of diverse stresses requires an accompanying assessment of multiple loads for individual ecosystems. In addition, in recent years, a consistent reaction of lakes to global climate changes has been demonstrated in different regions of the world, which emphasizes the need to study the role of both regional and local factors in regulating the response of individual lakes to this impact 6 . Comprehensive research in this area involving methods of ecology, hydrochemistry and hydrology is important for developing environmental standards to ensure the achievement of local water purity targets and the proper functioning of ecosystems.
Lake Baikal hosts an extremely complex ecosystem with a plethora of interspecies interactions 7 . The purity of its waters is passively supported by the low mineralization of the river inflow and actively maintained by the orchestrated work of the algal community (phytoplankton) and bacterioplankton in the pelagic zone [8][9][10] . The complex biochemical processes happening in this community maintain the balance of dissolved inorganic and organic matter in the water of Lake Baikal. Phytoplankton development leads to the accumulation of dissolved salts that contain biogenic elements as well as the transformation of those salts into insoluble forms.
www.nature.com/scientificreports www.nature.com/scientificreports/ Bacterioplankton, in turn, is responsible for the destruction of organic matter produced by the algae. In this way, dissolved matter is constantly leaving the water column and sinking to the bottom of the lake floor where it forms sediments. Diatom algae, which build their cell walls from dissolved silica, are a key component of sub-ice phytoplankton (a primary producer in lake Baikal) 7,8 . Thus, the stability of microalgal and bacterial communities maintains the water quality in Lake Baikal [7][8][9] .
During the last few years, there have been significant changes in the lake ecosystem, particularly in coastal zones [11][12][13] . In some low-depth areas (i.e., littoral zone), previously dominant species of the bottom phytocenoses have been replaced. Spirogyra, a filamentous alga indicative of eutrophication, has become widespread [11][12][13][14] . Studies have shown that minor ecological changes are also happening in the pelagic zone 15,16 . In particular, diatom algae endemic to the pelagic zone are being replaced by cosmopolitan species; this leads to a decrease in the total primary production of the lake 15,16 . Additionally, an increasing abundance of cyanobacteria has been reported in Lake Baikal's benthic communities 16 . It was hypothesized that changes in coastal ecosystems were triggered by an influx of biogenic elements, and that this influx, in turn, was caused by tourist activity near the lake compounded by a lack of sewage treatment facilities [11][12][13]17 . In contrast, changes in pelagic ecosystems are attributable to global climate change, which has shortened ice periods and increased the average temperature of surface waters 15,16 .
The phytoplanktonic and bacterioplanktonic communities of Lake Baikal are adapted to a specific combination of environmental factors [18][19][20] such as total dissolved salts, biogenic element availability, and water pH. Carbon is introduced to the lake ecosystem primarily via the photosynthetic carbon dioxide assimilation [21][22][23] , and in small quantities during bacterial consumption of methane and other hydrocarbons coming from the lake bottom 24 . Carbon dioxide concentration is a major factor affecting water pH due to the the reversible synthesis of hydrocarbonate (HCO 3 − ) and carbonate (CO 3 − ) ions 25 . An increase in the anthropogenic load on the lake ecosystem can also affect water pH. In Lake Baikal, acidification may happen in coastal areas near the outlets of heavily polluted rivers. Acidification is occurring in the rivers of Lake Baikal's southern basin 26,27 , caused by the emission of sulfur and nitrogen oxides from industry and heat-electric generation plants 27 . The pelagic zone in Lake Baikal's center remains relatively buffered from pH changes because of its volume; therefore, it can be used as a reference point when studying the lake's coastal areas.
Intensive phytoplankton growth during the spring accounts for most of Lake Baikal's primary production 19,20,[28][29][30] . These massive blooms happen in the euphotic zone (0-25 m) because of the accumulation of biogenic elements under the ice, including phosphates, nitrates, and carbon dioxide, as well as the dissolved silica necessary for diatom algae growth. During the spring (late March to early April for the southern basin), under-ice waters are heated by increasing solar radiation, and the massive diatom bloom begins, peaking near the end of ice season. This algal bloom produces easily-oxidized organic matter that allows bacterioplankton growth to intensify. Some phytoplankton and bacterioplankton is consumed by zooplankton, and organic matter moves to higher trophic layers. With the increase in solar radiation, algae and bacteria also begin developing on the ice-water boundary and in the ice pores, forming so-called ice communities 31 .
The main goal of this work was to study the hydrochemical parameters of water and the functional characteristics of the communities of algae and bacteria in ice water and in ice samples in estuarine zones of rivers with varying degrees of anthropogenic load, and assess the impact of stress factors of eutrophication and acidification on the course of key environmental processes. The complex analysis was aimed at studying the mutual influence of hydrochemical parameters, biological parameters, and the pH of the lake littoral.
Results
Sampling area and investigated parameters. In March 2018, water, ice, and snow were sampled from Lake Baikal's southeastern and southwestern coasts in the river mouths and from the lake waters near the rivers. Samples were also taken from two reference stations in the lake's pelagic zone (51.53875 N, 104.19746 E and 51.86710 N, 104.83247 E) (Fig. 1 (51.84429 N, 104.83949 E) pass through the Listvyanka settlement, which exhibits heavy tourism activity. The water from these rivers enters the Listvennichny Bay, which has fast water exchange with Lake Baikal.
This study examined two parameter categories. The first category describes the biological processes that occur in the studied waters (biological parameters): concentrations of organic carbon (C org ) and chlorophyll a (Chl_a), total phytoplankton mass (∑PB), total rate of methane oxidation (∑MO), count of organotrophic bacteria (OB), count of thermotolerant bacteria cultivated at 22 °C (TMC22C), count of thermotolerant bacteria cultivated at 37 °C (TMC37C), biogenic oxygen depletion (BOD), and total primary production rate (∑PP), which is the rate of light-dependent CO 2 assimilation, total bacterial count (NB), and total bacterial primary production (∑BP) which is the rate of dark-assimilation CO 2 . The second category includes the hydrochemical parameters relevant for the microbial community: concentrations of Na + , K + , Ca 2+ , Mg 2+ www.nature.com/scientificreports www.nature.com/scientificreports/ When the biological parameters were treated as dependent variables, the following qualitative and quantitative factors were found to significantly affect them: concentrations of Na + , K + , Ca 2+ , Mg 2+ , C(CO 2 ), Cl − , S(SO 4 2− ), P(PO4 3 − ), Si, HCO 3 − ; pH; the coast of Lake Baikal (western or eastern); and the biotope (water column or ice) (PERMANOVA analysis Table 1). The strongest effects (R 2 > 0.2) were observed for concentrations of Na + , K + , Ca 2+ , Mg 2+ , Cl − , HCO 3 − , P(PO4 3 − ), pH and sampling site (Table 1). Two major divisions between samples can be observed on the NMDS scatter plot (Fig. 2a). The first is more pronounced and separates the ice and water column samples. This division is statistically supported by the PERMANOVA analysis, since the biotope (ice or www.nature.com/scientificreports www.nature.com/scientificreports/ water column) is a significant factor that influences the values of biological parameters (Table 1). Water column featured higher concentrations of Na + , Ca 2+ , Mg 2+ , S(SO 4 2− ), and HCO 3 − , higher pH and lower C(CO 2 ) concentration. The second is less pronounced and separates the samples from the eastern and western coasts of Lake Baikal. This separation also confirms by PERMANOVA analysis (Table 1) When hydrochemical parameters were treated as dependent variables (Fig. 2b, PERMANOVA analysis Table 2), the following qualitative and quantitative factors were found to significantly affect them: C org , ∑PB, Сhl_a, ∑PP, BOD, NB, ∑BP, OB, TMC22C, biotope (water or ice) and Coast (western, eastern). BOD, NB, ∑BP, and biotope had the strongest effects (R 2 > 0.2). The ice and water samples (Fig. 2b, PERMANOVA analysis Table 2) differ in chemical composition. This usually comes from increased biological activity in the water samples (i.e., higher values of C org , ∑PB, Сhl_a, ∑PP, BOD, NB, OB and TMC22C). Some western water samples ( Fig. 2b) exhibited very high values of biological parameters C org , ∑PB, Сhl_a, ∑PP, BOD, NB, ∑BP, OB and TMC22C. Particularly high values of these parameters were observed for the water samples from the mouth of Bolshaya Cheremshanka river.
The investigated area of the western coast of Lake Baikal in the area of Listvyanka settlement, especially in the mouths of the rivers, also showed high values of biological parameters (implying high rates of biological processes) (Fig. 2). In addition to biological parameters that significantly affect hydrochemical variables, this sample had the highest counts of organotrophic bacteria (OB), thermotolerant bacteria cultivated at 22 °C (TMC22C), and thermotolerant bacteria cultivated at 37 °C (TMC37C). These samples showed high concentrations of Cl − , which is an indicator of anthropogenic pollution. One of the ice samples taken at the same site had an even higher Cl − concentration and lower bacterial and phytoplankton activity (roughly similar to other ice samples from the lake) (Fig. 2). All rivers (Kamenushka, Krestovka, and Bolshaya Cheremshanaya) flowing into the lake in the area pass through the Listvyanka settlement in sections ranging from 1.6 to 2.8 km (Fig. 1).
For both hydrochemical and biological parameters, parameter variance did not appear to correlate with the significance of the parameter's effect on the diversity of sampling sites (Tables 1 and 2). Parameters with high coefficient of variation between the samples (CV > 1) may have little impact on the patterns of other parameters. In contrast, parameters with low coefficient of variation (CV < 1) may affect other parameters with high significance and R 2 (R 2 > 0.3).
Analysis of the correlation between hydrochemical and biological parameters of samples from
under-ice water. Because the water samples were significantly different from the ice samples on both hydrochemical and biological parameters, only the water samples were used in the correlation analysis and heat map; When examining the areas of the heat map describing inter-cluster correlation coefficients, all values were either close to zero or negative. There were two pronounced groups with high positive correlation coefficients for intragroup correlations as well as high negative correlation coefficients for intergroup relationships (closely connected groups). The first group included a part of cluster A, particularly such hydrochemical parameters as P(PO 4 3− ), Mg 2+ , Cl − , HCO 3 − , Na + , Ca 2+ , K + , and water pH as well as such biological parameters as ∑PB, Сhl_a, NB, and BOD. The second group consisted of all variables from cluster D (i.e., N(NO 2 − ), N(NO 3 − ), S(SO 4 2− ), C(CO 2 ), Si, TMC22C, and OB). In general, an increase in the parameters of the former group caused a decrease in the parameters of the latter, and vice versa. network analysis of the correlation relationships between hydrochemical and biological parameters of samples from under-ice water. After correcting the P values for pairwise correlations between biological and hydrochemical parameters, only correlation coefficients (r) with absolute values above 0.5 were significant (p < 0.05). These pairwise correlation coefficients were used to build the interaction network (Fig. 4).
As with the heat map, there were two major groups of parameters in the interaction network. The first group included hydrochemical parameters such as P(PO 4 3− ) − , Mg 2+ , Na + , K + , Ca 2+ , HCO 3 − , Cl − , pH, and COD; and biological parameters such as C org, Сhl_a, ∑PB, ∑PP, ∑BP, and BOD. All of these parameters were positively correlated to each other. The second group included N(NO 2 − ), N(NO 3 − ), S(SO 4 2− ), C(CO 2 ), P(PO 4 3− ), Si, С(CH 4 ), OB, TMC22C, TMC37C, and ∑MO. All of these were also positively correlated to each other. In contrast, all of the edges between these two groups corresponded to negative correlations. In other words, increasing any parameter or group of parameters from the first group will (through a chain of interactions) lead to an increase in all parameters from the first group as well as a decrease in all parameters from the second group. The same can be said about the parameters in the second group. Thus, the results of the interaction network analysis are comparable to the results of the heat map.
Based on the number of edges, the parameters were separated into three groups. The first group included the parameters with a lot of connections (11)(12)(13)(14)(15)(16)(17)(18). More specifically, this group included P(PO 4 3− ), Mg 2+ , Na + , K + , Ca 2+ www.nature.com/scientificreports www.nature.com/scientificreports/ group featured the outliers with 1-4 connections: C(CH 4 ), C org , and ∑MO. Oxygen concentration (O 2 ) had no significant correlations at r > = 0.5.
All nodes had relatively low betweenness centrality (ranging from 0 to 0.174, with the highest possible value being 1) ( Table 3). Dissolved carbon dioxide concentration (C(CO 2 )) had the highest betweenness centrality value. This means that the shortest path between any two nodes in the network often passes through the C(CO 2 ) node. C(CO 2 ) also had the highest number of negative correlations, as shown by the number of negative correlation edges in the network. The nodes with the next highest betweenness centrality values were S(SO 4 2− ), N(NH 4 + ), and N(NO 2 − ) at the values of 0.105, 0.137, and 0.134, respectively. The two nitrogen concentrations N(NH 4 + ) and N(NO 2 − ) did not have a notable number of connections (7 and 9 edges, respectively). The group with betweenness centrality values between 0.05 and 0.1 included C(CH 4 ), Si, and water pH. Si − and water pH had a high number of correlations with neighboring nodes, while C(CH 4 ) was positively correlated with only two other parameters.
Discussion
The results of our study show that the coastal waters of Lake Baikal near Listvyanka settlement are under heavy anthropogenic load. All the Baikal tributaries in this area, as well as its coastal waters and ice, had an increased concentration of Cl − anion (from 1 to 4 mg L −1 in near Listvyanka compared to 0.11-0.6 mg L −1 at other sampling points), a marker of anthropogenic pollution 32 . Previous research has reported increased concentrations of Cl − in this area; those studies similarly interpreted this as evidence of anthropogenic load 13,17 . This raises questions regarding the exact nature of the pollutants. Water samples from this area also had high concentrations of organic carbon (from 2.5 to 4.85 mg L −1 in near Listvyanka compared to 0.85-1.99 mg L −1 at other sampling points) and high rates of biological oxygen depletion (from 1.6 to 3.2 mg O 2 L −1 in near Listvyanka compared to 0.1-1.2 mg O 2 L −1 at other sampling points). In addition, counts of organotrophic bacteria (from 550 to 6800 CFU mL −1 in near Listvyanka compared to 1-490 CFU mL −1 at other sampling points) and thermotolerant organotrophic bacteria (from 400 to 6000 CFU mL −1 TMC22C in near Listvyanka compared to 1-100 CFU mL −1 TMC22C at other sampling points) were significantly increased. Thus, it can be concluded that tributary rivers in this area are responsible for bringing organic matter from residential waste water into Lake Baikal. This waste water is not processed owing to the absence of central canalization and sewage treatment facilities in the settlement. This conclusion is further supported by the composition of these rivers' phytoplankton, which come mostly from the Cryptomonas genus, a common inhabitant of retention ponds. It should also be noted that we did not detect any significant increase in the concentrations of dissolved biogenic elements compared to water samples from other areas. At the same time, the littoral near Listvyanka settlement is one of the sites where we observed a massive www.nature.com/scientificreports www.nature.com/scientificreports/ development of filamentous algae and changes in bottom phytocenoses [11][12][13]33 . These changes may reflect a scenario in which residential waste, including a large volume of fecal mass, is washed into rivers by precipitation and then flows into Lake Baikal's littoral areas. A part of this organic matter sinks to the bottom, where it is destroyed by organotrophic bacteria. It is known 34 that human fecal matter contains increased concentrations of organic carbon, nitrogen, and phosphorus, which can be oxidized into bioavailable carbon dioxide, nitrates, and phosphates. As a result, near-bottom waters suffer a local increase in the concentrations of biogenic elements. Thus, in the littoral environment of lake Baikal near Listvyanka settlement at depths of 2-15 m, an abundance of biogenic elements, high water transparency (and therefore high solar radiation near the bottom), and an absence of strong waves combine to create a favorable environment for filamentous algae like Spirogyra. This scenario filamentous algae development in Lake Baikal at depths usually free of such species is similar to that observed in the Great Lakes 35 . The lack of a noticeable increase in the concentrations of biogenic elements in water column can be explained by the high rate of water exchange between Listvennichny Bay and the pelagic waters of Lake Baikal.
On the eastern coast of Lake Baikal, in both river mouths and surrounding areas, we observed an increase in the count of organotrophic bacteria. However, this increase was not as critical as on the western coast near Listvennichny Bay. Although the lower reaches of the studied rivers (Solzan, Malaya Osinovka, Bolshaya Osinovka) pass through the town of Baikalsk, Cl − concentration was not increased in these samples; moreover, the concentration of organic carbon and the biological oxidation rate were similar or even lower than at the reference sites in the pelagic area. This can be explained by the fact that Baikalsk has both centralized sewers and sewage treatment facilities where easily oxidizable organic matter is destroyed by bacteria, while organic nitrogen and phosphorus are converted into their soluble forms. In addition, the Baikalsk discharge pipe opens at a depth of 40 m, which is below the euphotic layer. This speeds up the mixing of wastewater with the main body of Baikalian water. One of the tributary rivers, the Pereemnaya, has not settlements at all. As such, the anthropogenic load on the Pereemnaya River is lowered. In all of the samples from the eastern coast, we observed increased concentrations of dissolved silicon and sulfates. This is primarily explained by the geological composition of the area that these rivers flow through; however, these results could also be affected by the fact that these rivers bring a much larger volume of water into Lake Baikal than do the rivers on the western coast 35 . The significant increase in sulfate concentration in the mouths of both Osinovka rivers is related to the fact that they flow near the Baikalsk Pulp and Paper Mill's storage area for liquid waste, and this liquid waste contains a substantial amount of dissolved sulfates 36 .
Compared to the under-ice water, the ice samples had decreased concentrations of Na + , K + , Ca 2+ , and Mg 2+ . This likely occurs because mineral ions are frozen out of the liquid phase during ice formation. Only one ice sample, taken from a reference station near the eastern coast of Lake Baikal, had an increased pH. This increased pH is attributable to the phytoplankton community that had begun to develop in the ice and that community's consumption of carbon dioxide. In general, the increased biological activity of ice communities and the increased mineralization of ice samples from the eastern coast are explained by environmental factors related to local www.nature.com/scientificreports www.nature.com/scientificreports/ winters. More specifically, there is a substantial buildup of ice caused by the inflow of silicon-and biogen-rich water from the rivers.
Our study shows that phytoplankton development in the under-ice community of Lake Baikal has remained largely unchanged in recent decades 7,8,20,25,28,29 . As solar radiation and temperature increase, pronounced algal development starts in the biogen-rich water. When the supply of biogenic elements is depleted, vegetation wanes. Our study fits with the results of earlier research reporting a decrease in carbon dioxide concentration during phytoplankton development [21][22][23] . In our dataset, carbon dioxide concentration ranked second after pH in terms of the number of correlations with other parameters. It exhibited more correlations than N(NO 2 − ), N(NO 3 − ), S(SO 4 2− ), N(NH 4 + ), P(PO 4 3− ), Si, and O 2 ( Table 3). In addition, carbon dioxide concentration had the highest betweenness centrality in the interaction network (Table 3) and was significantly correlated with the total biological activity of both phytoplankton and bacterioplankton (Table 2). Moreover, an analysis of the data from 22 shows that during spring, the concentration of carbon dioxide decreased faster as a percentage of the initial value than the concentration of other nutrients. It can be hypothesized that dissolved carbon dioxide is the major regulator of the primary production rate in Lake Baikal's under-ice phytoplankton. As phytoplankton grow and the supply of carbon dioxide is depleted, pH significantly increases. In these conditions, plankton is suppressed not only by the shortage of carbon available for biosynthesis but also by the inhibition of the proton pump apparatus responsible for the active import of other nutrient elements into algal cells.
A series of studies estimating the effect that oxidative stress caused by atmospheric pollution with sulfur dioxide (SO 2 ) has on freshwater lake phytoplankton detected the suppression photosynthesis, a decrease in primary production, and a lowering of microalgae taxonomic diversity at pH values under 5.7 [37][38][39][40][41][42] . The lowest pH value observed in our work was 5.76 in the ice sample taken near the Pereemnaya River on the eastern coast of Lake Baikal. This sample had a low rate of primary production and insignificant algal biomass. The concentration of carbon dioxide in this sample was higher than in all other samples, while the sulfate concentration was lower. These data confirm that a high concentration of CO 2 was responsible for low pH at this site. Thus, we can conclude that the water of Lake Baikal does not undergo significant acidification that could affect the activity of phytoplankton and bacterioplankton under the ice. Just as before, water pH is predominantly regulated by the photosynthetic activity of phytoplankton, which shifts the equilibrium in the reversible reactions of hydrocarbonate and carbonate synthesis. It is important to note that pH was significantly negatively correlated with Table 3. Numeric parameters of biological and hydrochemical variables as the nodes in correlation network built for water samples.
www.nature.com/scientificreports www.nature.com/scientificreports/ the concentration of both nitrates N(NO 3 − ) and sulfates S(SO 4 2− ). These strong acidic residues lower pH with increasing their concentration and are actively accumulated by phytoplankton. Thus, it is possible that this mechanism contributes to the changing pH balance in Baikalian waters. The role that photosynthetic N(NO 3 − ) and S(SO 4 − ) accumulation have on pH regulation merits additional study. Notably, however, study 43 provide evidence for a connection between sulfurous compounds and the activity of under-ice phytoplankton.
It is important to note that in Lake Baikal's littoral area, chlorophyll concentration and phytoplankton biomass were positively correlated with pH, which varied from 5.76 to 8. 16. In other freshwater lakes and rivers, primary phytoplankton production was negatively correlated with pH values in this range 37 , Si, and C(CO 2 )), were directly or indirectly negatively correlated with biological activity. These correlations are attributable to the consumption of these elements by the growing phytoplankton (Figs. 3 and 4). The only exception to this rule was phosphate (P(PO 4 − )) concentration. Phosphate concentration was positively correlated with the biological parameters. We hypothesize that phosphorus is a catalyst for all biological processes: the higher its concentration, the quicker phytoplankton grow. It should also be noted that the concentration of dissolved phosphates was extremely low in most samples, and very nearly at the lower limit of quantitative measurement. The role that phosphates play in phytoplankton development requires additional study.
Finally, the structure of the bacterial community was complex. Organotrophic and thermotolerant bacteria, which oxidize easily mineralizable organic matter, fell into a cluster of variables positively correlated with the biogenic element concentrations (N(NO 2 − ), N(NO 3 − ), S(SO 4 2− ), N(NH 4 + ), Si) which are formed from organic compounds consumed by these bacteria. The total bacterial count as measured by the fluorescent method (NB variable) (Figs. 3 and 4), including the count of cyanobacteria, fell into the same cluster as the other primary producers. Like diatoms, cyanobacteria consume biogenic elements and produce organic matter. Some other bacteria from NB are probably forming algae-bacterial communities and are responsible for the destruction of the specific forms of phytoplankton organic matter 44,45 . This would explain the close correlation between NB and biogenic oxidation rate (BOD) (Figs. 3 and 4). Unsurprisingly, the activity of methanotrophic bacteria was correlated to dissolved methane concentration (Figs. 3 and 4).
Our work is one of the first to apply an integrated approach to studying the mechanisms of functioning of the ecosystem of the water column of Lake Baikal. It allows us to conclude that when developing the standards for acceptable anthropogenic load on oligotrophic and ultra-oligotrophic lakes, it is necessary to take into account not only pollution by dissolved biogenic elements N(NO 2 − ), N(NO 3 − ), S(SO 4 2− ), N(NH 4 + ), P(PO 4 3− ), but also the flow of organic carbon. Large flow of organic matter of anthropogenic origin under conditions of high oxygen concentration will activate organotrophic bacteria producing carbon dioxide (CO 2 ). Large concentrations of carbon dioxide will activate photosynthesis processes causing undesirable consequences, including mass developments of filamentous algae and cyanobacteria.
Materials and Methods
Sampling. Water was sampled with a Niskin bottle at all sites, including from the river mouth as well as from the lake at a distance of 50-100 m in various directions from the mouth. Ice and snow were sampled at the same sites. At every point for chemical, microbiological and phytoplankton analyses, samples were taken in triplicate, followed by separate studys and averaging of the result. In the analyses of the primary production rate and total bacterial primary production rate, samples were taken in duplicate, followed by separate studys and averaging of the result. chemical analysis. Chemical analyses were performed using the methods commonly accepted in fresh water hydrochemistry [46][47][48] . Cations (Na + , K + , Ca 2 + , Mg 2 + ) were detected using atomic absorption and flame emission methods (relative precision 2-3%). Anions (Cl − , SO4 2− , HCO 3 − , NO 3 − ) were measured using HPLC (relative precision 5-10%). Biogenic element concentrations were measured using colorymetry (relative precision of −1,5% for phosphates and −3-5% for nitrates). Ammonium nitrogen was measured using the indofenol method (relative precision up to 5%). The reliability of the measured biogenic element concentrations was supported by a quality control analysis conducted according to EANET guidelines for testing reference samples of surface water. The measured concentrations of major ions were also controlled by calculating the error in ion balance and comparing the estimated and measured values of specific electrical conductivity. Dissolved oxygen was measured using iodometry according to Winkler, with a relative error of 1% 49 at the sampling site. The chemical oxygen depletion (COD) of oxidizing organic compounds was measured using the permanganate index. Biogenic oxygen depletion (BOD) was estimated with bichromate oxidizability. The relative error of both methods did not reach more than 10%. The concentration of organic carbon (C org ) was estimated using the catalytic high-temperature oxidation of samples at 850 °С followed by measurement of the produced СО 2 with an infrared detector on Vario TOC cube high-temperature carbon analyzer (Germany). The final result was calculated from the average of three measurements (standard deviation under 0.01%).
Methane concentration was measured with the «Headspace» method 50 on the «Эхо_EW» gas chromatograph with a flame ionization detector (Novosibirsk, Russia).
The pH of water, melted snow, and melted ice core samples was measured with a WTW pH 3310 device at the sampling site. www.nature.com/scientificreports www.nature.com/scientificreports/ Microbiological analysis. Microbiological analyses of water, ice, and snow samples were performed according to the МУК 4.2.1018-01 and МУК 4.2.1884-04. The total counts of colony-forming mesophilic aerobic and facultative anaerobic bacteria were estimated by culturing on meat-and-peptone agar at 37 °С for 24 h (TMC37C) and at 22 °С for 72 h (TMC22C), respectively. To estimate the count of organotrophic bacteria we used a medium based on fish-and-peptone agar (РПА:10) 51 . Petri dishes with the samples were incubated at 22 °С for 7 days, after which the colonies were counted. To measure total bacterial count (NB), the water, melted ice, and melted snow samples were fixed with 4% formaldehyde, stained with DAPI fluorochrome 52 , passed through polycarbonate filters (25 mm diameter, 0.2 μm pore size; Isopore, Merck, Germany) by means of a manual vacuum pump and analyzed under an epifluorescent microscope (AxioImager.M1, Carl Zeiss). total photosynthetic primary production rate (∑PP) and total bacterial primary production rate (∑BP). Sampling for the analysis and estimation of primary production rates was performed as described before. In accordance with previously published protocols, measurements of photosynthesis intensity and bacterial assimilation of carbon dioxide were taken using the radiocarbon method 53,54 . Microbial methane oxidation (MO). In accordance with previously published protocols, MO in sub-ice water samples was measured with the radiocarbon method ( 14 СН 4 ) 55 .
Phytoplankton identification. For phytoplankton identification, we fixed 1 L of water with Lugol's solution and then concentrated the phytoplankton via sedimentation. Algae were counted twice in a 0.1 mL Nageotte chamber under Peraval light microscopes with ×720 and ×1200 magnification. Algal biomass was calculated from the algal number using individual cell volumes 56 . To determine biovolume, 100-200 cells of each species were measured.
The chlorophyll a content was determined using the standard spectrophotometric method 57 .
Statistical analysis of the data. All numeric data were assembled into a single table; its rows correspond to the sampling sites, and its columns correspond to the measured parameters. Missing data were replaced with the averages for a given parameter 58 . Oxygen concentration (O 2 ), dissolved methane (C(CH 4 )), and total rate of methane oxidation (∑MO) were excluded from multidimensional scaling because technical problems prevented the estimation of these parameters for ice probes; moreover, using average values for all ice samples would have biased the data. The overall ordination of the sampling sites on all parameters was examined using non-metric multidimensional scaling (NMDS). Multidimensional scaling and analysis of significant explanatory variables were performed in R, using the «vegan» 59 package based on the tutorial 60 .
All data were transformed to eliminate the physical dimensions by ranging from zero to 1. For NMDS, the distance matrix was calculated using the Euclidean distance metric. Two analyses were performed. In the first analysis, biological parameters were treated as the dependent variables, while the abiotic hydrochemical factors were treated the explanatory variables. In the second analysis, calculations were reversed; the hydrochemical parameters were treated as the dependent variables, while the biological parameters were treated as the explanatory variables. This approach allowed us to characterize the interactions between two groups of variables in both directions. Fitting of the gradient vectors of quantitative explanatory variables in NMDS scatter plot was done using the «vegan» package function 60 .
Based on the Euclidean distance matrix, a PERMANOVA 61 analysis in «vegan» package was also performed to determine the relationship between dependent and explanatory variables. The analysis gives the values of R 2 coefficients which defined proportion of the variance in the dependent variables that is predictable from the independent variables. The reliability of the value of R 2 was calculated using 1000 permutations.
Pairwise correlations between all parameters (either biological or hydrochemical) were estimated with Spearman's r correlation coefficient. Pairwise correlations were visualized with a heat map generated using «gplots» in R. Lines and columns in the correlation matrix were clustered and grouped in order of similarity (i.e., Euclidean distance metric and the complete-link clustering method).
In addition, the correlation matrix was visualized as a network using the «qgraph» and «igraph» packages in R. The network topology was based on the number of links and correlation coefficients between neighboring nodes. The more links the nodes form among themselves, the closer they were placed in the network. Only reliable correlation coefficients (p < 0.05) were included in the network. P values for the correlation coefficients were calculated using Spearman's «W» statistics and corrected for false discovery rate in multiple comparisons using the Benjamini-Hochberg equation. To estimate the overall connectedness of the nodes in this network, we used normalized betweenness centrality 62 and each node's edge count.
code and data availability
Scripts for R programming language used for statistic analysis and initial data table with biological and hydrochemical parameters values are available at: https://github.com/barnsys/bac_phyt_communities. www.nature.com/scientificreports www.nature.com/scientificreports/
, HCO 3 − , Cl − ; concentrations of biogenic elements such as N(concentration of dissolved carbon in carbon dioxide C(CO 2 ) and methane C(CH 4 ); oxygen concentration (O 2 ); chemical oxygen depletion (COD); and water pH. Table with biological and hydrochemical parameters values are available at: https://github.com/barnsys/ bac_phyt_communities. Statistical analysis of hydrochemical and biological parameters of samples from ice and under-ice water. The result of the analysis of the relationship of hydrochemical and biological parameters is shown on the NMDS scatter plots Fig. 2. The statistical support for each factors are shown inTables 1 and 2.
Figure 1 .
1Map of the sampling sites. Sample numbers correspond to the numbers in in the
Figure 2 .
2Scatter plots of sampling sites in two-dimensional NMDS space. (a) parameters describing biological processes are treated as explained variables, hydrochemical parameters are treated as explanatory ones, (b) hydrochemical parameters are explained, biological parameters are explanatory. Red -eastern coast, bluewestern coast; green circles represent pelagic samples; circles -samples taken from the lake near river mouths, squares -river mouths; dashed blue squares are samples taken near the mouth of Bolshaya Cheremshanka river; dashed red pointers are samples taken near Bolshaya Osinovka and Malaya Osinovka rivers; w -water samples, i -ice samples. Plots show only the vectors of gradient for explanatory variables significantly affecting the datasets of explained variables(Tables 1 and 2).
. Western samples as a rule had higher Cl − and P(PO4 3 − ) concentration as well as lower concentrations of S(SO 4 2 ) − and silicon (Si). A particularly high concentration of Cl − and P(PO4 3 −) was in the sample of water and ice from the mouth of the Cheremshanka river(Fig. 2a).
of ice samples (n = 16) was not sufficient for a separate multivariate correlation analysis. Results of the multivariate correlation analysis are shown in Fig. 3 as a heat map. Based on the clustering, several groups of intercorrelated variables were identified. The largest group (cluster A) included hydrochemical parameters such as the P(2+ , Na + , K + , Ca 2+ , HCO 3 − , Cl − ; COD. This group also included biological parameters such as C org , Сhl_a, ∑PB, ∑PP, NB, ∑BP, and BOD. All of these parameters showed positive pairwise correlations with each other. The second group (cluster B) included three variables: N(NH 4 + ), C(CH 4 ), and the count of thermotolerant bacteria cultivated at 37 °C (TMC37C). These three variables showed slightly positive pairwise correlations. The third group (cluster C) included O 2 concentration and ∑MO. In most cases, these two parameters were weakly correlated, whether to each other or to other variables. The only exception was the correlation between ∑MO and C(CH 4 ). The correlation value for this pair was close to 1. The last group (cluster D) included seven parameters: N(NO 2 − ), N(NO 3 − ), S(SO 4 2 ), C(CO 2 ), Si, TMC22C, and OB. All variables within this cluster were strongly positively correlated with each other.
, HCO 3 − , Cl − , S(SO 4 2− ), Si, C(CO 2 ), COD, BOD, NB, Сhl_a, ∑PB, ∑PP, and water pH. Among these parameters, S(SO 4 2− ), pH, Si, and C(CO 2 ) had the highest number of negative correlations. The second group had a moderate number of correlations (6-10 edges). Among its members are N(NH 4 + ), N(NO 2 − ), N(NO 3 − ), ∑PB, OB, TMC22C, and TMC37C. Parameters in this group had very few negative correlations (0 or 1
Figure 3 .
3Heat map of pairwise correlation coefficients for biological and hydrochemical parameters. Parameters in the heat map are ordered according to the clustering based on similarity of correlation coefficient vectors. Clusters discussed in text (A, B, C, D) are shown on the clustering dendrogram.
Figure 4 .
4The network of correlations between all measured parameters (both biological and hydrochemical). Blue shapes mark the parameters related to the bacterial activity, green circles mark the parameters related to phytoplankton activity, black squares -mineral ion concentrations, green squares -concentrations of biogenic elements, pentagons mark the rate of biogenic and chemical oxidation of organic matter. Green edges mean significant positive correlations, red edges mean significant negative correlations.
. Thus, the Baikalian phytoplankton complex is adapted to function under low concentrations of carbon dioxide. Microalgae are able to consume CO 2 and other biogenic elements at high pH.The concentrations of all biogenic elements in the water, including (
CO 2 concentrations were calculated based on HCO 3 − concentration, pH, and the total mineral content of the solution22 .
). The lower reaches of the Solzan (51.49722 N, 104.15836 E), Bolshaya Osinovka (51.50056 N, 104.24403 E) and Malaya Osinovka (51.50056 N, 104.25354 E) rivers pass through the town of Baikalsk and its industrial area. The Pereemnaya River (51.56891 N, 105.16609 E) does not pass through any settlements in its entire course. The lower reaches of the Kamenushka (51.84457 N, 104.87505 E), Krestovka (51.85535 N, 104.85970 E), and Bolshaya Cheremshanaya rivers
Maps were taken from the Google Earth Pro software (https://www.google.com/intl/ru/earth/versions/#earth-pro). «Inkscape» (https://inkscape.org/) free graphics editor was used to edit images and apply additional marks to maps.table with the initial
data (https://github.com/barnsys/bac_phyt_communities). Geographic coordinates of stations (degrees and
decimal places): St1 51.56891 N, 105.16609; St2 51.49722 N, 104.15836 E; St3 51.50056 N, 104.25354 E; St4
51.50056 N, 104.24403 E; St5 51.53875 N, 104.19746 E; St6 51.84457 N, 104.87505 E; St7 51.85535 N, 104.85970
E; St8 51.86710 N, 104.83247 E; St9 51.84429 N, 104.83949 E.
Table 1. PERMANOVA analysis results for the assessing the statistical significance of the influence of hydrochemical parameters in sampling sites on the complex of biological parameters.Parameter name
Average
value
Coefficient of
variation (CV)
PERMANOVA
analysis
R 2
P value
Quantitative variables
Na + concentration (mg L −1 )
2.16
0.77
0.30
0.0009
K + concentration (mg L −1 )
0.75
0.69
0.24
0.0009
Ca 2+ concentration (mg L −1 )
10.09
0.66
0.27
0.0009
Mg 2+ concentration (mg L −1 )
1.88
0.75
0.26
0.0009
HCO 3
− concentration (mg L −1 )
37.99
0.75
0.27
0.0009
C(CO 2 ) concentration (mg L −1 )
1.29
1.55
0.08
0.038
Cl -concentration (mg L −1 )
0.64
1.31
0.27
0.0009
N(NO 2
−
) concentration (mg L −1 )
0.0030
2.44
0.05
0.09
N(NO 3
−
) concentration (mg L −1 )
0.30
1.98
0.05
0.09
S(SO 4
2−
) concentration (mg L −1 )
2.027
0.77
0.06
0.027
N(NH 4
+ ) concentration (mg L −1 )
0.012
1.86
0.18
0.003
P(PO4 3
−
) concentration (mg L −1 )
0.013
2.26
0.30
0.0009
Si concentration (mg L −1 )
0.86
1.13
0.07
0.019
Chemical oxygen depletion (COD) (mg O 2 L −1 ) 3.25
0.64
pH
7.36
0.10
0.245 0.0009
Qualitative variables
Sampling site
0.27
0.015
Sampling zone(river mouth, near-mouth littoral
water, pelagic water)
0.04
0.3
Coast(western, eastern)
0.09
0.038
Biotope (water or ice sample)
0.171 0.0009
). The thirdTable 2. PERMANOVA analysis results for the assessing the statistical significance of the influence of the biological parameters in sampling sites on the complex of hydrochemical parameters.Parameter name
Average
value
Coefficient of
variation (CV)
PERMANOVA
analysis
R 2
P value
Quantitative variables
Organic carbon concentration (C org ) (mg L −1 )
1.94
0.4
0.177 0.0009
Total phytoplankton biomass (∑PB) (μg L −1 )
48.08
0.9
0.165 0.0009
Chlorophyll a concentration (Сhl_a) (μg L −1 )
0.96
1.23
0.144 0.0009
Total rate of primary production (∑PP) (μg C L −1 day −1 )
7.68
1.28
0.154 0.0009
Biological oxygen depletion (BOD) (mg O 2 L −1 )
0.71
0.77
0.23
0.0009
Total bacterial count (NB)(cells mL −1 )
930.58
1.07
0.44
0.0009
Count of organotrophic bacteria (OB) (CFU mL −1 )
390.54
3.20
0.12
0.0009
Count of thermotolerant bacteria cultivating at 22 °C (TMC22C)(CFU mL −1 )
219.78
4.5
0.12
0.0019
Count of thermotolerant bacteria cultivating at 37 °С (TMC37C)(CFU mL −1 )
17.14
3.36
0.024 0.30
Total bacterial primary production (∑BP) (μg C L −1 day −1 )
0.63
0.66
0.28
0.0009
Qualitative variables
Sampling site
0.24
0.06
Sampling zone(river mouth, near-mouth littoral water, pelagic water)
0.04
0.34
Coast(western, eastern)
0.11
0.021
Biotope (water or ice sample)
0.46
0.0009
© The Author(s) 2020
AcknowledgementsThis work was supported by RFBR grants 17-29-05040_ofi_m «Microbial communities of Lake Baikal and their metabolic potential in areas with elevated concentration of organic matters of natural and anthropogenic origin» (sampling, microbiological analysis, phytoplankton analysis, data analysis) and the State Task № 0345-2019-0007 «Geobiochemical studies of the methane cycles…» (chemical data).competing interestsThe authors declare no competing interests.Additional informationCorrespondence and requests for materials should be addressed to Y.S.B.Reprints and permissions information is available at www.nature.com/reprints.Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Open Access This article is licensed under a Creative Commons Attribution 4.0 InternationalLicense, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
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Production of exometabolites in the microbial oxidation of methane in marine ecosystems. I I Rusanov, A S Savvichev, S K Yusupov, N V Pimenov, M V Ivanov, Mikrobiologiya. 67in RussianRusanov, I. I., Savvichev, A. S., Yusupov, S. K., Pimenov, N. V. & Ivanov, M. V. Production of exometabolites in the microbial oxidation of methane in marine ecosystems. Mikrobiologiya. 67, 710-717 (in Russian) (1998).
Methods on sampling and processing materials in hydrobiological studies of fresh water-bodies. State Research Institute of Fish Industry Design. , Winberg, G G , Leningradin RussianWinberg,, G.G. Methods on sampling and processing materials in hydrobiological studies of fresh water-bodies. State Research Institute of Fish Industry Design.(Leningrad 1984) (in Russian).
Report of SCOR-UNESCO Working Group 17. Determination of Photosynthetic Pigments. ParisReport of SCOR-UNESCO Working Group 17. Determination of Photosynthetic Pigments, (Paris: UNESCO. 1964).
Handling missing attribute values in preterm birth data sets. International Workshop on Rough Sets, Fuzzy Sets, Data Mining, and Granular-Soft Computing. J W Grzymala-Busse, L K Goodwin, W J Grzymala-Busse, X Zheng, SpringerBerlin, HeidelbergGrzymala-Busse, J. W., Goodwin, L. K., Grzymala-Busse, W. J., Zheng, X. Handling missing attribute values in preterm birth data sets. International Workshop on Rough Sets, Fuzzy Sets, Data Mining, and Granular-Soft Computing. 342-351 (Springer, Berlin, Heidelberg. 2005).
The vegan package. Community ecology package. J Oksanen, 10Oksanen, J. et al. The vegan package. Community ecology package. 10, 631-637 (2007).
Vegan: an introduction to ordination. J Oksanen, R ProjectOksanen J. Vegan: an introduction to ordination. R Project, https://cran.r-project.org/web/packages/vegan/vignettes/intro-vegan. pdf (2018).
A new method for non-parametric multivariate analysis of variance. M J Anderson, Austral ecology. 26Anderson, M. J. A new method for non-parametric multivariate analysis of variance. Austral ecology. 26, 32-46 (2001).
. L C Freeman, Centrality in social networks conceptual clarification. Social networks. 1Freeman, L. C. Centrality in social networks conceptual clarification. Social networks. 1, 215-239 (1978).
| Although the changes in plankton community composition that result from lake acidification have been documented, little is known about processes that accompany these changes. Here we report investigations on an important process, zooplankton herbivory, in an experimentally acidified lake. Acidification from pH 6.2 to 5.2 has not directly impaired the ability of several major taxa to gather food. Acidification may indirectly affect selective feeding behavior, through changes in the relative abundance of phytoplankton species. Dramatic shifts in population-level grazing were not reflected in overall community herbivory, because of complementary changes in populations in the reference and treatment lake basins. Hence, integrative system-level functions may be poorer indicators of perturbation than specific, fine-scale processes. | Multiple temporal scale analysis of main driving factors of eutrophication in Meiliang Bay,Lake Taihu | An Ecological Dynamics Model of Algae Growth in Taihu Lake and the Analysis of its Influencing Factors | Field investigations were conducted to identify environmental variables influencing phytoplankton dynamics in Lake Poyang. The results showed that diatoms predominated in the phytoplankton community. Concentrations of nutrients were high, and levels of phytoplankton biomass and chlorophyll a were low. During the low water level period (WLP), , phytoplankton biomass decreased again. Highest values were generally measured in the middle district and lowest in the northern district. It decreased from October 2013 to January 2014. Redundancy analysis showed that water temperature and suspended solids (SS) concentrations were the principal factors regulating the growth of phytoplankton. The variations in SS were contrary to the biomass variations at the spatial level.During the high WLP, the blocking effect of the Yangtze River led to decreased water velocity and prolonged water retention time in Lake Poyang. Due to both the SS sedimentation and increase in water temperature, phytoplankton grew rapidly. Based on these findings, the variety of phytoplankton dynamics was caused by the combined effects of the Yangtze River effect, water temperature, and SS. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited | Concentrations and sinking rates of particulate biogenic silica (BSi), chlorophyll a (chl a) and phaeopigments (phae) ( 10 μm and total), as well as the abundances of the major phytoplankton species, were studied during September 1991 in the Eastern Laptev Sea and the lower Lena River (Siberian Arctic). The highest chl a concentrations were found in two major “new” production regimes of the study area: (1) a deep chl a maximum (5.8 mg chl a m−3) (formed by the diatom Chaetoceros socialis) at 30 m depth on the outer shelf of the northern Laptev Sea, and (2) in the Lena River, where the phytoplankton community was dominated by fresh water diatoms (1.5 to 4.5 mg chl a m−3). Elevated chl a concentrations were also found in the river plume phytoplankton community (dominated by brackish water diatoms), NE of the Lena delta. In the Laptev Sea, the low chl a (0.1 to 3 mg chl a m−3) and high phae concentrations (0.5 to 14 mg phae m−3) indicated that the phytoplankton community (dominated by picoplanktic algae and nanoflagellates) was already senescent and affected by grazing losses. Biogenic silica values were highest in the Lena River (4 to 17 μM) as compared to the low values found in the Laptev Sea (0.3 to 4 μM). The large chl a size fraction, phae and BSi in the Lena River samples revealed the highest measured sinking rates (1.4, 2.3, and 1.5 m d−1, respectively). The formation of a strong halocline, decreasing turbulence, and possible nutrient deficiency resulted in death, disintegration and rapid sedimentation of fresh water diatoms. This was accompanied by a decrease in the BSi concentration and growth of the picoplanktic size fraction (< 3 μm) in the estuarine mixing zone (Gulf of Buorkhaya). Only a minor part of BSi was bound to intact diatom cells (< 3%) in the surface layer, most of which being apparently associated with detrital particles. In the Lena River, approximately 12% of the total silica was bound to BSi fraction, yet elsewhere in the Laptev Sea and in the estuarine mixing zone the BSi:total silica ratio was ≤ 5%. Thus, the results reflected the successional stage of a late summer phytoplankton community, characterized by dominance of small autotrophs and patchy distribution of senescent diatoms no longer able to affect the relative high levels of dissolved silica supplied by the Lena River. | Factors controlling the activity of the microbial community of the alkaline Lake Beloe (Transbaikal Region) | Sestonic biochemical composition (lipids, proteins and carbohydrates) may change with varying environmental fluctuations. These changes and the effects in the nutritional status of algae consists of an actual increasing source of interest. The aims of this work were to establish the relationship between biochemical composition of seston and 1) a range of physical, chemical and climatological factors, and 2) the natural fluctuation in the species composition in phytoplankton assemblages of the Pampulha Reservoir, an urban eutrophic lake located in Belo Horizonte, MG. Seasonal changes in the biochemical composition were observed in this study. None of the considered abiotic factors alone seem to affect the biochemical composition. So the effects could only be understood by interactions among different environmental factors. On the other hand, the dominant algal groups probably have some influence in the observed changes in biochemical composition of seston. | Intermittent wetlands are particularly at risk from secondary salinisation because salts are concentrated during drawdown. We conducted a field experiment to examine the effect of adding salt at two different concentrations (to achieve nominal conductivities of 1000 μS cm–1 (low salt) and 3000 μS cm–1 (high salt)) on water quality, freshwater plants and epiphytic diatoms in an intermittent wetland during a 3.3-month drawdown. Conductivity increased to 3000 and 8500 μS cm–1 in low-salt and high-salt treatments respectively. Salt was apparently lost to the sediments, causing protons to be released from the sediments and reducing water column pH from 6.9 to 5.5 in the low-salt treatment and to 4.0 in the high-salt treatments. Forty days after adding the salt, biomass, %cover and flower production in Potamogeton cheesmanii were significantly reduced, whereas Amphibromus fluitans was not significantly affected. The salt effect on Triglochin procera was intermediate between the other two macrophytes. Significant reductions in the density, species richness and diversity of epiphytic diatoms occurred in the high-salt, but not in the low-salt, treatments. Our work shows that increases in salinity, and thus conductivity (up to 8500 μS cm–1), in low-alkalinity intermittent wetlands can change water quality, with significant adverse effects on some macrophyte and diatom communities. |
1,999,734 | i love the product but herbs it come with most of ... | great herbs. i was using the cloves for the parasite cleanse. not to get into details, but very detoxifying and effective. i've ordered herbs from the dr. clark store and have always been satisfied. | Outstanding for people who haven't studied herbs or don't know much about them. This is very informative for basic knowledge of home remedies! | This book is exactly what i needed! Some people are upset about it not giving more info but it's an Encyclopedia, Not a story book! It's very handy ;D it lists the common name, latin name and all the necessary info along with a drawing of each herb. | This book makes it easy to identify herbs. Too many herbals give a name and description. With the illustration I have identifyed several valuable plants that I thought were weeds. | I needed this ingredient which I had never herd of and low and behold here it was on Amazon!! I ordered a extra bottle to give as a gift to a friend since the price was so fair. This spice is really nice and makes the lentil stew taste awesome! Thank you. | I rely enjoy reading the National Geographic guide to medicinal herbs. I am learning a lot about plants around us. | What is the most expensive herb in the world? | Herbalism harm, that whole herbs are more effective than molecules isolated from the plants, herbs are superior to drugs, the doctrine of signatures (the belief that the shape of the plant indicates its function) is valid, dilution of substances increases their potency (a doctrine of the pseudoscience of homeopathy), astrological alignments are significant, animal testing is not appropriate to indicate human effects, anecdotal evidence is an effective means of proving a substance works and herbs were created by God to cure disease. Tyler suggests that none of these beliefs have any basis in fact. Up to 80% of the population in | 1,999,734 | i love the product but herbs it come with most of them are poor quality and alot of similar herbs and i tried to call about the free refills got no where :/ | Herbal RVA Premium MD (Kilo, Unopened) | Received Plaquenil refill yesterday | These supplements are a great price! I have been giving them to my ... | Purchasing herbs & oils? | I've been happy with the Davidson's herbs I've bought. | which respond well to the natural benefits of this most wonderful herb. I am pleased that it is available ... | I Need Help Evaluating Ingredients Of A PMS Relief Herbal Product! I Want To Become An Affiliate, But First I'm Looking For A "Thumbs Up" From A More Experienced Herbalist. | Where can I get free condoms in Ottawa? |
1,999,735 | Psych Research Methods 2820E instead of 2800/10? | Which one of these courses has an A+ attainable. Note: Biol 3150 is currently being offered by Dr. Golemi-Kotra. 3155 is being offered by Dr. Andrew White. 3140 have Dr Chris Jang and Dr. Sweeney as the course directors.
Also, is do you guys think that 3140 is very TA dependent? Kinda like 2070, in the sense that one TA can put ur grade to the ground and others are really helpful “at least thats how I felt”. | (The previous thread
There is a trend that I notice in the previous thread: it seems like everyone arguing in favor of NLP is unfamiliar with how psychological research is conducted. Psychology is a soft science, making it fundamentally different from hard sciences like physics or chemistry. What this means is that you can do an experiment in physics, for example, and expect that every replication of that experiment is probably going to get the same results. This is not the case for psychology.
Recently, researchers tried to replicate 100 experiments conducted ten years before, and almost two thirds of them failed to replicate--though we do know why they failed, and what the ones that didn't fail did right. Because human minds are so variable, it is very easy to delude ourselves into believing finds that simply aren't true, but scientists have developed methods that make it more difficult to self-delude: the gold standard is a double-blind RCT with a large sample size and an appropriate P-value.
To put this in layman's terms, it means very little if you've used the Fast Phobia Cure 10,000 times, and in every single case the client benefited. As Irving Kirsch showed in his 1985 study, just telling a client that they're on the waiting list to be treated later conveys psychological benefit. If you can't show that your 10,000 clients benefited significantly more on average than clients put on a waiting list, you haven't demonstrated anything.
You'll notice that in many studies suggesting that NLP works, there's no control group. The experimenter has never compared NLP to anything else, including placebo. They're making exactly the mistake I describe above.
So, to break this down into two parts:
1. Is there any technique unique to NLP that seems to be useful?
2. Is there any research suggesting that said technique works? | Summary Eighty-seven hospitalized male and female psychiatric patients had successfully completed the SPI and MMPI and were rated for severity of psychopathology by their ward psychologist and psychiatrist. A stepwise multiple regression method was used to develop best sets of test predictors of combined judges' ratings. For the SPI the best four-variable combination consisted of the scales External Control, Spacial Confinement, Dependency, and Warm Weather Minimizing. For the MMPI the best four-variable combination consisted of Paranoid Obvious, Low Back, Depression-Subtle and L. | I dont know whether to take CSCE 121 with John Moore or Teresa Leyk. John Moore has terrible reviews on rate my professor and Teresa has way better reviews, but the labs are 8 am. Has anyone taken either and have any thoughts? Thanks! | requires providers to use a depression screening instrument when treating depression. Studies found the PHQ-9 is also useful for screening for depression in psychiatric clinics. Studies have used the PHQ-9 to study patients with diabetes, HIV-AIDS, chronic pain, arthritis, fibromyalgia, epilepsy, and substance abuse. It also is used in studies involving patients with physical disabilities as well as older adults, students, and adolescents. The PHQ-9 is available in over 30 languages and it has been validated for use in different ethnicities. Currently Pfizer owns the copyright of the PHQ-9, but allows it to accessed for free. The PHQ-2 is a | requires providers to use a depression screening instrument when treating depression. Studies found the PHQ-9 is also useful for screening for depression in psychiatric clinics. Studies have used the PHQ-9 to study patients with diabetes, HIV-AIDS, chronic pain, arthritis, fibromyalgia, epilepsy, and substance abuse. It also is used in studies involving patients with physical disabilities as well as older adults, students, and adolescents. The PHQ-9 is available in over 30 languages and it has been validated for use in different ethnicities. Currently Pfizer owns the copyright of the PHQ-9, but allows it to accessed for free. The PHQ-2 is a | PSYCHLOPS (Psychological Outcome Profiles; Ashworth et al., 2004) is a patient-generated outcome measure developed to be a sensitive indicator of change after therapy. It requires the patient to choose which symptoms or problems are most important to measure over the course of therapy. The present study replicates previous findings for the original version and validates the Icelandic version. The psychometric properties of PSYCHLOPS were investigated by comparing it to an established nomothetic outcome measure, CORE-OM. Icelandic versions of both questionnaires were administered to patients attending cognitive behavior group therapy in a mental-health setting in Iceland. PSYCHLOPS was found to be considerably more sensitive to change over therapy than CORE-OM; convergent and concurrent validity was supported, and internal reliabilities were satisfactory. The acceptability of the instrument was demonstrated by the high completion rate. Overall, these findings suggest that the Icelandic version of PSYCHLOPS... | The background and development of a multicategory direct observation system, the Behavior Observation Instrument (BOI), is described. This time-sampling procedure for recording the behavior of persons is demonstrated in several treatment settings and the results applied to issues of program evaluation. Elements that have prevented direct observation from being widely adopted, such as costs, manpower, and training requirements, are systematically analyzed. A basic psychometric analysis of the instrument is used to determine optimum frequency and duration of observation intervals as well as observer agreement. The results imply that direct observation methods, once assumed by some to belong to the special province of the single-subject design, can be used to assess the effects of programs on groups of psychiatric clients in an efficient and economic manner. | 1,999,735 | I'm wondering if anyone who has taken 2820E could give me advice on progression through the honours spec Psych module. Since I only had 0.5 math credits first year instead of the required 1.0 I have to take 2820E alongside stats 1024A instead of the recommended 2800 and 2810 combo.
My concern is that since this is a single 1.0 credit course it won't fulfill the requirements that the 2800/2810 (2.0 credits) serve for upper year courses. So, for anyone who has been in a similar spot, will this course act as a pre-req for the same courses that 2800/2810 would in upper year classes?
Thanks.
PS. sorry for not going to Academic counselling, I work M-F. | How silly would it be to take COMP 283 and MATH 233 in the same semester? | Psych 2820 vs Psych 2800e + Psych 2810 | Advice for Biol 180???? Projected grade is 2.9 right now. | Taking MATH 240 P/F vs. Taking the Credit Exam Next Sem | How many credits is advisable in FYE first semester ??? | Taking comm 215 and 217 in the same semester? | Which section to pick for English 302 for Accounting Major? | What courses do I have to worry about? I am a senior in high school and have been looking at this subreddit and calc 135 looks pretty depressing. I am going to be pre-med and have thoughts on majoring in psychology. |
1,999,736 | Head units that support Android audio over USB | I've talked about it many times before and I want to layout what I hope Google, OEMs and third parties do because it'll take the work of all three parties to do this.
Let's be honest...Google hasn't always been audio friendly even before Android became a foundation of their company with YouTube having horrible audio standards for a few years before they made audio acceptable. Now that Android is mature now it's time for it extend outside of the typical phone/tablet features and think about it using it for more niche or even professional tasks. Since this subreddit is focused on audio and I'm mostly knowledgeable about audio and sound I would love to lay out what I want to see on Android.
The fact that L is having native USB audio shows that Google is trying to be more serious about audio...while USB audio is amazing and much needed feature I would love more customizable drivers. Vipers4Android is a really good fix but it really should be native to Android. Another thing that Google needs to do is have audio standards for higher end phones. It needs to at least have a decent DAC that's not integrated as of right now. There needs to be a push from Google towards decent built in headphone amps too on higher end phones but it shouldn't be a requirement right now due to logistics of that. Maybe if Google bought out Fiio they can set a standard of DACs and headphone amps thus supplying cheap high quality AMPs and DACs to OEMs.
OEMs need to put most of their money on the headphone amp and DAC even if they were to offer a specialty audiophile edition of the device that would be a welcome start. OEMs also need to form close relationships with headphone manufacturers. I could see OEMs subsidizing headphones to compete directly with Beats. It would work be a win win for the headphone manufacturer and the OEM.
Third parties should do all the pro audio and super niche audiophile. I should be able to plug in a high end tablet into an audio interface that's connect to a DJ mixer (or DJ mixers need USB audio in) and use it as a deck/controller for example. There are thousands of applications that pro audio could use with USB audio and that would put us leagues above Apple.
One thing that no one should do is focus on phone/tablet speakers. Yes they should be at least front facing and stereo but other than that unless there's a major revolution in speaker technology (carbon nanotube speakers maybe?) there are never going to sound good or have a good frequency response and dynamic range. Loudspeaker technology hasn't changed much in the last years and it all works on the same principles. | i do a lot of driving for work and it would be nice to display google maps directly from the head unit while playing music via bluetooth. i could really use some recommendations. i was looking at the android Auto head units but not sure if i want to go that route | I bought Alien Isolation on PS4 the other day, and I've been looking forward to LPing it on my YouTube channel (I know I know, LPing is a dead horse, but it's fun to do). Of course in survival horror games the audio is everything, so I want to wear a set of headphones while I play - but plugging in headphones mutes all audio on the TV. This means that if I were to record footage, there'd be no audio feedback.
The question I'm getting to is: is there a way to have audio come from my headphones AND my TV at the same time? | Did not work with my Android device as previously thought (Could only hear sound from left ear and controls did not work). Called customer service and they confirmed that these are only compatible with Apply devices. | since the update is out for background music is it possible to listen via USB?? | Great headset, but sadly I wasn't paying attention.
NOT USB, just to give anyone in the future a heads up.
This is 3.5mm jack. | I will say up front the hardware design and general feel of the MixAmp was very good. In regard to how it functioned for me is an entirely different story. Upon hooking up the MiXamp to an Xbox One X via optical cable/ USB to PC / Headset jack to headset / and stream port to LINE IN on PC I heard what sounded like a dying Pterodactyl coming out of my headset at high volume. So I disconnected the stream port in order to at least get the mixer functional and I experienced very low mic volume output to the point that others could not hear me on discord etc. The mic volume slider was at 100% and as you may know already there is no boost option with usb mics on windows 10. The common workaround for this is to install an application that can boost your output such as "VoiceMeeter." I contacted Astro support and they are clearly on auto-response as these are the steps they sent back a day or so after I emailed them:
Thank you for contacting ASTRO Gaming.
Please provide the firmware version numbers shown in the Astro Command Center.
Under the mic settings in the ACC, change your noise gate to "streaming" and make sure the mic level is maxed. Click "sync to device" after making these adjustments.
If you are still having mic issues with your mixamp after this, perform these troubleshooting steps:
- Make sure your Windows/OS is updated <------------------------------------------ Already was
- Use a different USB cable to connect your mixamp to your PC. <---------------- Tried but I question what is wrong with their cable if so
- Connect to a USB 2.0 port, not 3.0. <---------------------------------------------------- Most modern PC's won't even have usb 2.0 ports. Mine does not.
- Reinstall your USB/audio drivers <-------------------------------------------------------- Used Treexy to remove / reinstall. No impact.
- Test your headset on another PC/laptop or Reinstall Windows <----------------- Tested the MixAmp on a laptop and same effect. Refuse to reinstall.
- Provide a screenshot showing your playback/recording devices. <-------------- Done
Astro support gave this response on Mar 21, 10:16 AM PDT and I have not gotten a reply after providing them information.
I hope your experience is better than mine but in the end I went with the Turtle Beach TAC and it works like a champ out of the box on the same PC that I was attempting to use the Mixamp. | I was looking for an adapter that would allow me to plug a 2.5mm headset of my choice (i.e., a mike & earpiece for hands-free operation) into my Samsung SGH-T219. Unfortunately that's not what this item does. On the Bargaincell website, it's pretty clear-- they say "For audio / music output only. Audio input not available." I wish it had been worded that clearly in this listing.
Searching around there seems to be a lot of adapters that do what this one does, and none as far as I can tell that do what I want. (If you happen to know of one, it'd be great to hear about it via a comment. TIA.) | 1,999,736 | So I've been doing a bit of research and would love to get a new head unit that supports audio over USB on an android phone.
From searching around, a lot of threads I've found indicate that audio over USB from an android phone (using AOA) frequently either
A) doesn't work at all or
B) is plagued with chirps and audio cutouts every so often
I'm limited to single din head units because of my budget and vehicle (mostly budget since I'd want a capacitive touchscreen screen on a double din, and those get pricey), but does android auto (as opposed to AOA) solve this problem? If so I may reconsider my budget to get a dual din and make it fit the vehicle.
Anyone have info on whether there are any newer head units that actually work well with AOA (or other protocols) to get audio over USB from an android device? Or am I still stuck using bluetooth to get audio from my android phone (HTC10 in case that matters)?
Thanks!
Edit - for clarification I'm looking to stream audio from sources like spotify and google play music via USB, not to play audio files from my phone. | Where Android should go into next with audio... | Controlling audio from an android wear device? | Is there an app to pass input into the 3.5mm jack out to bluetooth headphones? | Bluetooth headsets that work with Linux? | MP3 players running Android - are there any amazing devices? | Good USB soundcard interface | HTML5 Audio on mobile devices currently sucks? | is there a way to use the realtek audio driver enhancements with a usb headset? |
1,999,737 | Maintaining your vibration | How to realize what your current vibration is? What should one do to go higher from their current vibration after realizing it? How to know that you are attracting someone with a higher vibration or at the same level as you? | What causes mobile vibration? | Good and sturdy product. Easy to use. Not sure what the vibration does for me but does what it says! | Ever since I switched from the game pad controller to the fight stick to get used to the gamecube controller layout and now that I actually am used to and playing on the gamecube controller, I turned the vibration off as it seemed like a disruption, but now that I need to learn more muscle memory things for getting out of situations, did anybody switch from no vibration to vibration in this case? for example, knowing when I'm gonna land a short hop fastfall nair and then knowing what to follow up with based on what I felt in the vibrations. Weird question but I wanna know if having the controller vibrate garners any benefits.
**TL;DR:** are there any benefits in having the controllers vibrate as opposed to having them not? | Subjective Response to Whole-Body Vibration | Just starting my work experience/internship with a general engineer who specialises in vibration analysis, so would like to get a bit of an idea behind the process.
I did a course on this a while back, but no longer have access to the online resource... | Vibration Perception Thresholds Assessed by Two Different Methods in Healthy Subjects | On ps4, there’s been a few times where the controller vibrates mildly, when there’s nothing around (that I can see) to make it vibrate. It’s reminiscent of Red Dead Redemption 2, where the controller vibrates when you’re near something interesting.
Searching didn’t pull anything up, I assume that means there’s no vibrate-near-interesting-things mechanic? | 1,999,737 | Hello all!
I usually mediate first thing in a morning, followed by a cold shower. This raises my vibration & gets me ready for my day.
However. I’ve noticed at work a few hours in my vibration lowers. I enjoy my job & it is a relaxed environment to the point where I could break off & go & meditate for a short while (obviously not ideal to be doing during work time).
I was wondering if there are any other techniques to maintain my vibration throughout the day? I try & steer away from coffee unless I need that extra boost.
Thank you all, and have a lovely day! 💙 | How to keep your energy levels and work intensity/focus up throughout the day? | How to raise your vibration when you’re PMSing? | how to maintain strength while time off | Productive things I can do during downtime at work? | [Need Advice] Is anyone else really productive in the morning but lose steam half way through the day? How do you stay productive? | Recommendations and interventions to decrease physical inactivity at work | Any suggestions to help avoid energy slumps? | Any tips on how to concentrate during the day? |
1,999,738 | anderitum was a well-established fishing port and producer of what | Caballito de totora Caballitos de totora are reed watercraft used by fishermen in Peru for the past 3000 years, archaeologically evidenced from pottery shards. Named for the way they are ridden, straddled ('little reed horses' in English), fishermen use them to transport their nets and collect fish in their inner cavity. The name is not the original name, as horses were not introduced to South America until after the Spanish conquest of the Inca Empire. They are made from the same reed, the totora ("Schoenoplectus californicus" subsp. "tatora"), used by the Uru people on Lake Titicaca. Fishermen in the port | The status of natural resources of Andrias davidianus was analyzed,the root causes for decreases were discussed,and the countermeasures for protection were put forward.The results showed that overfishing,damaged habitats and polluted water quality are the main causes;protecting eco-environment,breeding and releasing are significant measures for protection of natural resources of A.davidianus. | Pacific coast on both the north and the south side of the Columbia's mouth. At times, however, the Chinook territory extended even farther south in the Willamette Valley. The total native population was estimated at about 15,000. The indigenous peoples of the Willamette River practiced a variety of life ways. Those on the lower river, slightly closer to the coast, often relied on fishing as their primary economic mainstay. Salmon was the most important fish to Willamette River tribes as well as to the Native Americans of the Columbia River, where white traders traded fish with the Native Americans. Upper-river | Ospia is an extinct genus of neopterygian ray-finned fish that lived during the Induan age of the Early Triassic epoch in what is now Greenland.
See also
Prehistoric fish
List of prehistoric bony fish
References
Parasemionotiformes
Early Triassic fish | Protomyctophum andriashevi is a species of lanternfish which is circumpolar in the Southern Ocean. It is sometimes called Andriashev's lanternfish.
References
Lampanyctus
Fish described in 1963 | Nine sedimentary sequences are recognized in the Ordovician of the Siberian Platform. These sequences correspond to sea level fluctuations of the 3rd order, from 1 to 6 My. Correlation with the sequences recognized in the Ordovician of the Russian Platform suggest their possible eustatic nature. Cold water nontropical carbonates are suggested in the Ordovician of the Tungus Syneclise, which may be explained by the upwelling of cold oceanic waters. The upwelling was caused by re-distribution of oceanic currents due to largescale tectonic events in the mid-Ordovician. The Ordovician evolution of the Siberian Platform was much more similar to that of the North American Platform than of the Russian Platform. | Orcadian Basin The Orcadian Basin is a sedimentary basin of Devonian age that formed mainly as a result of extensional tectonics in northeastern Scotland after the end of the Caledonian orogeny. During part of its history, the basin was filled by a lake now known as "Lake Orcadie". In that lacustrine environment, a sequence of finely bedded sedimentary rocks was deposited, containing well-preserved fish fossils, with alternating layers of mudstone and coarse siltstone to very fine sandstone. These flagstones split easily along the bedding and have been used as building material for thousands of years. The deposits of the Orcadian | Rearing of sharpsnout seabream (Diplodus puntazzo, Cetti 1777) in a Mediterranean fish farm: monoculture versus polyculture | 1,999,738 | Anderitum The fort appears to have been resettled by about the middle of the 6th century by a Saxon community which left evidence of its occupation in the shape of pottery, glass and other items. By the late Anglo-Saxon period, Pevensey had become a well-established fishing port and producer of salt. When William the Conqueror launched his invasion of England by landing at Pevensey Bay on 28 September 1066, his army sheltered for the night in a temporary fortification situated within the old Roman fort. The army left for Hastings the following day, en route to the Battle of Hastings. It | in which war did the british land in åndalsnes | which english explorer sailed to the ternate in 1580 | when did the british invade the northern states | when did the british take part in the battle of cádiz | where did the english capture valencia in 1706 | Question about the Battle of Pelennor Fields | who did roger mortimer capture in the invasion of england | which king was defeated at the battle of entzheim in 1674 |
1,999,739 | when was community radio started in south africa | effective immediately. South African Broadcasting Corporation The South African Broadcasting Corporation (SABC) is the public broadcaster in South Africa, and provides 19 radio stations (AM/FM) as well as five television broadcasts to the general public. During the 20th century, it was also known in Afrikaans as Suid-Afrikaanse Uitsaaikorporasie (SAUK), but this has since been depreciated and is used only when referring to the corporation in the spoken word on SABC2's Afrikaans TV news and on the Afrikaans radio station Radio Sonder Grense. However, the Afrikaans newscasts on SABC2 use "SABC Nuus" instead of "SAUK Nuus". The term is still used | South Africa required SAfm to re-add drama and children's radio programmes, and these are now among the station's offerings. Most SAfm listeners are in age range of 35 to 49, and LSM groups 7–10. SAfm SAfm is a national, English-language public radio station in South Africa. It has been operated by the South African Broadcasting Corporation (SABC) since its foundation in 1936. SAfm was the SABC's first radio station, and the country's first public radio station. From 1924 to 1936, the only radio service in South Africa was a privately owned station called JB, which broadcast to the cities of | Namibian Broadcasting Corporation in February 1976 in the Kwangali, Mbukushu and Gciriku languages. In 1965, the pro-independence movement, the South West Africa People's Organisation (SWAPO), began broadcasting a one-hour radio programme from Tanzania on short wave known as "The Namibian Hour". It later started broadcasting from Zambia. In 1974, it was renamed Voice of Namibia. By 1986, it was broadcasting from Angola, Congo, Ethiopia, Madagascar and Zimbabwe, as well as from Tanzania and Zambia. In May 1979 the SABC relinquished control of these services, when the South West African Broadcasting Corporation (SWABC), known in Afrikaans as "Suidwes-Afrikaanse Uitsaaikorporasie" (SWAUK), came into being. However, | Media of South Africa services as well as IPTV services such as video-on-demand, never took off and was subsequently sold to Shenzhen Media South Africa. On Digital Media is 68% black owned. Radio has always been South Africa's biggest broadcast medium; From the 1960s, South Africa was a world leader in FM radio technology. In 1962, five FM radio stations broadcast, each to a particular language group. The content of the broadcasts ranged widely, over music, sports, religion, current affairs and drama. By the mid 1980s another five languages had their own stations and four music-only regional, commercial broadcasters had been added to the | Afrikaans had been the only official languages used by all South African governments before 1994. However, in the Kwazulu bantustan the Zulu language was widely used. All education in the country at the high-school level was in English or Afrikaans. Since the demise of apartheid in 1994, Zulu has been enjoying a marked revival. Zulu-language television was introduced by the SABC in the early 1980s and it broadcasts news and many shows in Zulu. Zulu radio is very popular and newspapers such as "isoLezwe", "Ilanga" and "UmAfrika" in the Zulu language are available in Kwazulu-Natal province and in Johannesburg. In | Radio Teemaneng Stereo 89.1 FM is a South African community radio station based in the Northern Cape.
Coverage Areas & Frequencies
Kimberley
Warrenton
Kuruman
The borders of the Free State
Broadcast Languages
English
Afrikaans
Xhosa
Tswana
Broadcast Time
24/7
Target Audience
LSM Groups 1 – 8
Age Group 16 – 49
The Black Community
Programme Format
65% Music
35% Talk
Listenership Figures
References
External links
SAARF Website
Sentech Website
Radio Teemaneng Stereo FM Website
Radio stations in South Africa | Namibian Broadcasting Corporation The Namibian Broadcasting Corporation is the public broadcaster of Namibia. It was established in 1979, under the name South West African Broadcasting Corporation. Radio was originally broadcast in English and Afrikaans via shortwave from the South African Broadcasting Corporation's facilities in South Africa. The SABC introduced FM services in November 1969, relaying Radio South Africa, Radio Suid-Afrika and Springbok Radio, and establishing a number of services in native languages, including Radio Ovambo, broadcasting in the Kwanyama and Ndonga languages, Radio Herero and Radio Damara Nama. The introduction of Radio Kavango along the northeastern border with Angola followed | CCFM (Cape Community FM) is a 24-hour, (when there is no load shedding) 7-day-a-week community radio station serving the people of Cape Town, South Africa. As a non-profit radio station who must adhere to ICASA Community Broadcasting regulations, CCFM broadcasts a mix of contemporary Christian music, combined with talk, views and interviews, and up-to-the-minute news, weather, and traffic information. Its slogan is “Changing lives for good.”
CCFM started as Radio Fish Hoek in 1993. The station was founded by the Fish Hoek Baptist Church. It currently broadcasts in Cape Town, False Bay, Stellenbosch, Goodwood, Fish Hoek, Simon’s Town, and Atlantis on 96.7 & 107.5 FM. English is its primary language, but airs some Xhosa & Afrikaans as well.
CCFM styles itself as a Christian radio station, boasting about 152,000 listeners as of October 2014. About 10% are younger than 25, a quarter of listeners are 25–34, a third 35–49, and 30% are 50 or older. The sex of the audience breaks 48% male, 52% female.
References
Radio stations in Cape Town | 1,999,739 | Community radio in South Africa In South Africa, Community Radio refers to a non-profit, service-oriented radio that is solely owned and operated by the community, with no government interference. It encourages communication and connects the people of the community and across cultures. Since the commencement of Community Radio in the early 1990s, it has become increasing popular, especially in rural communities. Community radio’s rise in South Africa is attributable to the dismantling of apartheid and an example of building a democracy and civil society within the country. The community radio division was officially formed in 1993 by a parliamentary Act | Mobilizing rural and community radio in Africa | Community Radio, Funding and Ethics | who was the founder of community radio | The Power of the “Audience-Public”: Interactive Radio in Africa | Method and practice in participatory radio: rural radio forums in Malawi | A future for community radio in Australia: Funding, licensing and legislative issues. | [Community] Irrational Radio is looking GMs and Players to join our growing community! | where was the first kwaito radio station launched in south africa |
1,999,740 | Carotenoids of Anacystis nidulans, structures of caloxanthin and nostoxanthin | Gibberellic acid (GA3) generally increased the contents of chlorophyll but not carotenoid in bothChlamydomonas reinhardii andAnacystis nidulans grown under continuous irradiation. The photosynthetic oxygen evolution of the algae was also affected by GA3 except for the high (100 μM) concentration of GA3. | Of a number of possible buffers only HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) supported continued and maximum growth of photoautotrophically grown Anacystis nidulans when grown in medium C and aerated with air (0.03% CO2). Cultures aerated with 1% CO2 in air had adequate buffering without the use of additional buffers in medium C. With either air or 1% CO2 grown cells, phosphate and TRICINE (N-tris-hydroxymethyl-methylglycine) buffers gave growth rates of 67% compared to HEPES buffer while complete inhibition of growth occurred with TRIS (tris-hydroxymethylaminomethane) buffer. | Carotenoids are a diverse group of pigments widely distributed in nature. The vivid yellow, orange, and red colors of many horticultural crops are attributed to the overaccumulation of carotenoids, which contribute to a critical agronomic trait for flowers and an important quality trait for fruits and vegetables. Not only do carotenoids give horticultural crops their visual appeal, they also enhance nutritional value and health benefits for humans. As a result, carotenoid research in horticultural crops has grown exponentially over the last decade. These investigations have advanced our fundamental understanding of carotenoid metabolism and regulation in plants. In this review, we provide an overview of carotenoid biosynthesis, degradation, and accumulation in horticultural crops and highlight recent achievements in our understanding of carotenoid metabolic regulation in vegetables, fruits, and flowers. | The utilization of microalgae as a source of carotenoid productions has gained increasing popularity due to its advantages, such as a relatively fast turnaround time. In this study, a newly discovered Coelastrum sp. TISTR 9501RE was characterized and investigated for its taxonomical identity and carotenoid profile. To the best of our knowledge, this report was the first to fully investigate the carotenoid profiles in a microalga of the genus Coelastrum. Upon use of limited nutrients as a stress condition, the strain was able to produce astaxanthin, canthaxanthin, and lutein, as the major carotenoid components. Additionally, the carotenoid esters were found to be all astaxanthin derivatives, and β-carotene was not significantly present under this stress condition. Importantly, we also demonstrated that this practical stress condition could be combined with simple growing factors, such as ambient sunlight and temperature, to achieve even more focused carotenoid profiles, i.e., increased overall amounts of the aforementioned carotenoids with fewer minor components and chlorophylls. In addition, this green microalga was capable of tolerating a wide range of salinity. Therefore, this study paved the way for more investigations and developments on this fascinating strain, which will be reported in due course. | The tropical plant Bixa orellana L. (annatto) is the sole source of bixin, the most frequently employed natural pigment in the food industry. Little is known about the physiology, biochemistry, and molecular genetics of this crop. Our purpose was to establish a set of analytical tools that could be applied in the genetic improvement of B. orellana, particularly for the screening of characteristics such as bixin content and resistance to diseases or pests. Some preliminary results on the study of carotenoid synthesis are presented. In vitro cultures from several B. orellana tissues were established and DNA, RNA, and proteins were extracted from them and analyzed. Similarly, bixin and total carotenoids were quantified. | Carotenoids are Found in Chloroplasts Carotenoids are fat soluble pigments, meaning they do not readily dissolve readily in water. Instead, they are usually found attached to proteins or membranes in the chloroplasts. Chloroplasts (see Figure 2) are tiny organelles in cells where photosynthesis occurs. | Colorimetric estimation of Carotene in Enteromorpha intestinalis, a se.awe~d of the family of Ulvaceans abounding in the Lake of Rez?,yeh, has. proved ?' Vlt~rrlln activity of this plant corresponding to 3000 Internatlonal Umts of vitamin A approximately. | The changes in the carotenoid pigments of Capsicum annuum cv. Szentesi Kosszarvu during maturation have been investigated quantitatively by means of a HPLC technique. In all of the chromatograms, 56 peaks were detected; 34 carotenoids were identified. In this study, special attention is paid to the formation of minor carotenoids with 3,6-epoxy-β- (oxabicyclo[2.2.1]) and 3,5,6-trihydroxy-β- end groups. The possible biosynthetic route and the identity of capsolutein with the cucurbitaxanthin A are described. Keywords: Capsicum annuum; carotenoids; analysis; biosynthesis | 1,999,740 | Abstract Reinvestigation of the carotenoids of Anacystis nidulans has confirmed the occurrence of β,β-carotene (β-carotene), β,β-caroten-3-ol (cryptoxanthin), β,β-carotene-3,3′-diol (zeaxanthin) and 2R,3R,3′R-β,β-carotene-2,3,3′-triol (absolute configuration assigned in the present work). In addition the previously unknown 2R,3R,2′R,3′R-β,β-carotene-2,3,2′,3′-tetrol has been isolated. The triol and the tetrol are considered identical with caloxanthin and nostoxanthin, respectively, for which allenic structures have been suggested by others. The chirality of these compounds followed from CD and 1 H NMR considerations. | Separation and identification of the yellow carotenoids in Potamogeton crispus L. | Richter1 and Fewson et al.2 have both reported that fructose diphosphate (FDP) aldolase activity could not be demonstrated in blue-green algae, especially Anacystis nidulans. A peculiar steady-state growth condition induced by uric acid as sole nitrogen source and characterized as a severe nitrogen deficiency has been found in a marine species of blue-green algae: Agmenellum quadriplaticum, strain ‘PR-6’. In this condition 45 per cent of the cell dry weight was a glucose polymer3. Certain enzyme systems in the uric acid grown cells of ‘PR-6’ were examined in an attempt to gain some idea of the possible pathway for glucose formation. In the course of these experiments an active aldolase was found. This communication deals with the demonstration and some characteristics of the aldolase found in crude extracts of Anacystis nidulans, with supporting data from ‘PR-6’ and one other blue-green alga. | Advance in Antitumor Activity and Molecular Mechanism of β-Carotene | Where are chlorophyll a chlorophyll b and carotenoids locaed? | The oft-claimed ‘good’ water solubility of the food color norbixin (3) could not be confirmed. In contrast, the potassium salt 5 of norbixin formed suitable dispersions. The surface and aggregation properties of salt 5 were investigated and compared with other naturally occurring and synthetic hydrophilic carotenoids (Table). | Carotenoids are organic lipophilic yellow to orange and reddish pigments of terpenoid nature that are usually composed of eight isoprene units. This group of secondary metabolites includes carotenes and xanthophylls, which can be naturally obtained from photosynthetic organisms, some fungi, and bacteria. One of the microorganisms able to synthesise carotenoids is the heterobasidiomycetous yeast Xanthophyllomyces dendrorhous, which represents the teleomorphic state of Phaffia rhodozyma, and is mainly used for the production of the xanthophyll astaxanthin. Upgraded knowledge on the biosynthetic pathway of the main carotenoids synthesised by X. dendrorhous, the biotechnology-based improvement of astaxanthin production, as well as the current omics approaches available in this yeast are reviewed in depth. | Isolation and Determination of A New Carotenoid | Synthesis, Antioxidant Activity and Cytotoxicity of N-Functionalized Organotellurides |
1,999,741 | Update: NotAMom Shows Up at Niece's Moving Up Ceremony | My little girl turns 8 soon. I haven't been to church in years, but my wife attends with the kids every week. She is my oldest. What's the best way to tell her I'm not going to be able to do the ceremony? | The Family Nobody Wanted decide to pursue adoption of "unadoptable children." Finally, they are contacted about a two-month-old baby girl. The birth parents are Filipino-Chinese and English-French. Helen names her Laura after Carl's mother. Two weeks later they adopt Susie, who is blond with blue-eyes, but considered unadoptable because she is frail/sickly and has a birth mark on her face. When Donny gets older, he wants a brother "just his size." Many of the subsequent adoptions occur as a by-product of trying to find Donny's missing brother. The Dosses adopt a total of 12 children. In their final adoption, when Donny is 9, they | At the end of the day name somethin indianna jones might put away in her closet? | So this afternoon, I finally got bored enough to check the updates on Pandoras Vow Renewal group.
For those who read the last post, she has not disappointed.
For those who have not been following along, I advise checking those out first, but long story short my selfish narcissistic FMIL Pandora has recently decided that she and SFIL (the great enabler) need to renew their vows because gifts. Initially planned it for the day my sister actually gets married next spring to cause friction with DP and I, and when that backfired, moved it to his mid week july birthday, then moved it to the weekend after people said they couldn't attend mid week. Theres now a facebook group where she posts updates on the wedding plans.
There have been quite a few updates since last I checked in.
The date is now confirmed. The date which her own parents are not available due to a pre booked family holiday to the states. The holiday is not adjustable due to school holidays and fees increasing the next week. So her parents will not be attending her "wedding". A few pointed posts have been made about not caring if people dont attend, and not putting it off for anyone to attend because if they cared they'd be there.
Last weekend she bought a whole mess of foam and silk roses and beady things to make bouquets for herself and her bridesmaids. The bouquets she didn't want. She posted photos. They look like a 10 year olds arts and craft project. Shes also having about 6 bridesmaids. The roses are in 2 very different shades of cream, 1 being more orangey. Each of the bridesmaids bouquets has 7 of the cream roses, then around the middle rose are 5 tiny blue paper roses. Then there are blue raspberry type beady things squished in. Hers is about 12 cream foam roses with white raspberry beady things. They are a hot mess. And will most likely be a bit rubbish looking when we finally get to next july. My sister hasnt even bothered purchasing her bouquets yet, as she doesnt want them to be ruined in storage for 6 months.
This update made me giggle. They've booked the DJ. And a face painter. And are considering a bouncy castle. Is this a wedding or a kids birthday party. The number of kids invited is not worth the cost imo. Unless shes expecting us adults to sit down and have some randomer paint our faces into tigers and dogs and butterflies.
Every damm day she has posted about being excited. Every. Single. Day. We still have 11 months to go. | I was just watching the latest episode of counting on and I was really irked by how Jinger kept referring to and talking about standing up on the "stage" for her wedding. I was raised catholic and I'm actually in the midst of planning my wedding and I would never refer to the altar as the stage.
Maybe the Cathedral of the Ozarks has a stage instead of an altar but it just seemed odd to me that for such a Christian family, they wouldn't talk about getting married at the altar and instead call it the stage.
Or maybe their faith is just so non-traditional that they don't really use the altar anymore?
Or, even worse, maybe she just thinks of her wedding as a big show and she's just performing on a stage?
Did anyone else notice this? | Niece is to nephew? | I got married yesterday and it was perfect and made me so so happy. However, my JNMIL said a few things as we were all lined up to walk down the aisle that made me go "really?"
First, when she saw me in my dress for the first time, she says pretty sarcastically "well, you look kinda nice."
Next, my maid of honor was speaking kinda loudly and my day of coordinator asked everyone to quiet down and JNMIL goes "of course it's (MOH name). It's always been her. Y'know, we all thought MOH and D(ear)H would be the ones getting married" seconds before walking her son down the aisle to marry me. She's been saying things like this about my MOH the whole time DH and I have been engaged. MOH and DH have been really good friends since kindergarten, but nothing more and MOH and I were best friends in high school. She introduced DH and I and I love her to death.
I didn't hear this last comment luckily. I just heard about it from others after the wedding. Everything else was perfect though.
Update: we found her card. The front of it says to my son and "daughter". Just like that. With the quotations and everything. And the quotations continue throughout the card. | I don't see any hard evidence to suggest she's shunned or isolated. If anyone is isolating her, it's Derick. And to be fair, she has a husband in law school, obviously one vehicle, and two young boys. Except for the pants , which Jinger started wearing first, and nose ring, she has followed all the rules. People though Jinger was shunned a while back because Jim Bob and Michelle didn't visit her in Texas. As this article says, is that enough evidence to say she got shunned? If any daughter got shunned, it should be Jinger when you think about it.
ETA If anyone should have been shunned, it should be the eldest J not necessarily for what he did but ruining the brand first. .
| 1,999,741 | The day after NotAMom's appearance, I had a talk with SiL and her partner (will be simply Partner for the rest of ths story) and learned a few more things. Oh and NotAMom left us another message close to 8 last night (probably cause she knew hubs would definitely be home). Here we go.
* It was asked in my original post if SiL had invited NotAMom without telling us. Completely undersandable given the flying monkeys in this sub. SiL has been NC with NotAMom for years now at the suggestion of her therapist. Poor thing was nervous as hell with NotAMom there. We still have no idea how she found out or got a ticket.
* SiL was inside with Niece while Partner was in their car before everything started. NotAMom ended up walking by with her land lady's son (Kid from here on out). Partner overheard Kid say to NotAMom "don't worry I won't let anyone kick you out". This leads me to believe she's been putting stories in his head. Like WE would risk ruining Niece's day over her. Fuck you, NotAMom, ever the victim.
* Partner was on the way in when NotAMom, still outside, ran up and hugged her. They haven't talked after Partner found out about all the things NotAMom has done to SiL and family. But here is NotAMom, getting all up in Partner's personal space.
* After we went out the back way to the car, Partner went to get Niece. She had told SiL to wait in the car. NotAMom saw we weren't with Partner and asked where we were. Kid chimes in saying he saw us go out the back. "OH, did they not want me to see the babyyyyy?" Yes, NotAMom, exactly. Partner just shrugs and leaves with Niece.
* NotAMom left us a message last night. We were home but hubs was busy and didn't want to talk to her. Message is as follows: Hi [hubs] it's NotAMom, my number is blahblahblah (again, we KNOW WHAT YOUR NUMBER IS WOMAN). I'm sorry I didn't catch you before you left last night. I was waiting for you but you slipped out the back and I didn't catch you (we know, it was on purpose you hag). The baby looked SO adorable. I'll talk to you soon, call me.
NotAMom will be getting a call, from ME, later. Should be fun. | Help me (42M) get over the fact my wife (47F) counts a past hookup as family | The girl [f22] I'm [m25] sleeping with doesn't know I slept with her younger sister [f20] before we started. | MIL(F4M) Be a good boy and tell me about your mommy issues | How to approach GF [28F] who's behavior has been odd without (cheating maybe?) | MIL is blaming my husband for not seeing our son due to COVID | MIL is insulted that we requested her fiance to be respectful of personal space with our young kids | [ADVICE] How should I handle a no contact nMom during family events? | I thought it was MiLs you were supposed to dislike ... not your own mother |
1,999,742 | Italian Firefighters mom says two thumbs up.... | In Melbourne, Fla., firefighters responding to emergencies were in such a rush that they forgot to turn off a fryer in their kitchen. A firefighter from Cocoa Beach drove by and noticed smoke escaping from the firehouse, so he call 9-1-1. Firefighters then returned to battle the fire at their own station. | Two women, two children found dead after fire | The New Zealand Fire Service was devastated by a spate of firefighters being convicted for arson. VINCENT ARBUCKLE details the measures taken by the service to prevent this happening again. | How do the italians say mom and dad? | I'm on Book 2 Chapter 2 of The Crown and The Flame and something is absolutely stumping me. Was there a scene where Kenna finds out about Dom's fire power???? Why isn't she surprised at all when actual fire is coming from his hands? Did I miss it or did they just not address it at all? | Firefighters hope to have full control of Greece's worst forest fires in memory within the next four days, the fire brigade said on Saturday. | This is the best tl;dr I could make, original
*****
> A Massachusetts fire lieutenant died early Wednesday after helping two firefighters escape a burning home after they all became trapped on the third floor.
> Worcester fire Lt. Jason Menard, 39, was pronounced dead at a hospital from his injuries.
> The firefighters were called to the four-alarm fire at the home just before 1 a.m. Flames were extending from the second floor to the third floor when they arrived.
> Lavoie said Menard and his crew received a report that a resident and a baby were trapped on the second floor of the building, but &quot;Heavy fire conditions&quot; caused the firefighters to become trapped on the third floor.
> &quot;Fire conditions overtook the third floor at this time and Lt. Menard was unable to escape,&quot; he said.
> Lavoie described the lieutenant as a &quot;Passionate fire officer who absolutely loved being a firefighter."
*****
**Summary Source**]( | [FAQ]( "413089 summaries so far.") | [Feedback | *Top* *keywords*: **firefighter**^#1 **fire**^#2 **floor**^#3 **third**^#4 **Menard**^#5
Post found in /r/news]( [/r/FreshNewsToday]( and [/r/nofeenews.
*NOTICE*: This thread is for discussing the submission topic. Please do not discuss the concept of the autotldr bot here. | Firefighters show even big macho guys can live & grow without meat....shows how one changes his life by choosing healthier plant-based diet. | 1,999,742 | Coming from a long line of firefighters from back east (Connecticut) in my own family I was very conforted by this book and the messages that go with the awesome recipies!
Many comfort foods from my childhood...and gourmet' recipes to boot...!!
Having two firefighters in my family, Micah 24 Firefighter in Iraq and back home again, and Caleb age 21 locally and does wild land fire crew in the summer, who also like to cook...and cook for the crews and cook well.. They have received a copy for a gift. Thanks to John for the time and care he obviously has for the "GUYS"!! | Wow what an amazing book an the recipes are all based on Fire | Great camp fire food. | Love this cookbook and donating to the cause! | Nicely written Amish story, combining many lives through cooking classes. | Helped my teenager branch out and learn more about cooking! | Fallout Cookbook Thoughts? | how long was ted reader a grill chef on cottage country | This book is full of great ideas for camping or even backyard BBQ |
1,999,743 | The effect of Fe2O3and ZnO nanoparticles on cytotoxicity and glucose metabolism in lung epithelial cells | Zinc oxide nanoparticles (ZnO NPs) have been widely used in consumer products, therapeutic agents, and drug delivery systems. However, the fate and behavior of ZnO NPs in living organisms are not well described. The purpose of this study was to develop a physiologically based pharmacokinetic model to describe the dynamic interactions of 65ZnO NPs in mice. We estimated key physicochemical parameters of partition coefficients and excretion or elimination rates, based on our previously published data quantifying the biodistributions of 10 nm and 71 nm 65ZnO NPs and zinc nitrate (65Zn(NO3)2) in various mice tissues. The time-dependent partition coefficients and excretion or elimination rates were used to construct our physiologically based pharmacokinetic model. In general, tissue partition coefficients of 65ZnO NPs were greater than those of 65Zn(NO3)2, particularly the lung partition coefficient of 10 nm 65ZnO NPs. Sensitivity analysis revealed that 71 nm 65ZnO NPs and 65Zn(NO3)2 were sensitive to excretion and elimination rates in the liver and gastrointestinal tract. Although the partition coefficient of the brain was relative low, it increased time-dependently for 65ZnO NPs and 65Zn(NO3)2. The simulation of 65Zn(NO3)2 was well fitted with the experimental data. However, replacing partition coefficients of 65ZnO NPs with those of 65Zn(NO3)2 after day 7 greatly improved the fitness of simulation, suggesting that ZnO NPs might decompose to zinc ion after day 7. In this study, we successfully established a potentially predictive dynamic model for slowly decomposed NPs. More caution is suggested for exposure to 65ZnO NPs <10 nm because those small 65ZnO NPs tend to accumulate in the body for a relatively longer time than 71 nm 65ZnO NPs and 65Zn(NO3)2 do. | Metal Oxide Nanoparticles in Therapeutic Regulation of Macrophage Functions | Green tea leaves mediated ZnO nanoparticles and its antimicrobial activity |
Introduction
Metal oxide nanoparticles, due to their distinctive properties (optical, electrical, and magnetic), are applied in many areas including energy storage, sensors, optics, coatings, piezoelectric, and biotechnology [1][2][3]. Zinc oxide nanoparticles are an important class of metal oxide materials, because of their unique physical, electrical, chemical, optical, biological and medical properties. They are suitable for many applications such as solar cells, ultraviolet photodiodes, catalyst, semiconductors, gas sensors, piezoelectric devices, coatings, antibacterial and medical [4][5][6][7]. In addition, due to their resistance to the UV-radiation [8] and antimicrobial properties [9] they are used in transparent UV-protection films and as a UV-filter in sunscreens, and in the process of canning food lining, respectively. Recently, ZnO nanoparticles achieved an effective presence in biomedical and agricultural soils applications [10][11][12]. Many methods have been used to synthesize various ZnO nanostructures, which include physical vapor deposition, chemical vapor deposition, thermal decomposition and thermal evaporation process [13][14][15]. These techniques are complex, have a high cost, and require high temperatures. Hydrothermal method is considered as a distinctive alternative method in the fabrication of nanomaterials because it is a process which involves low temperature, simple equipment usage, low cost, and is environmental friendly. Additionally, it has a good control on particles size, structure and morphology of the products. It has been applied to prepare ZnO nanoparticles and other luminescent materials [16][17][18][19][20]. The aim of the present work was to prepare ZnO nanoparticles using hydrothermal method and study the influence of reaction time and reaction temperature on their properties. The structure and morphology of the obtained nanostructure product was characterized by using several analysis techniques.
Experimental
Materials
In ZnO nanoparticles synthesis, Zinc acetate di-hydrate [Zn(Ch3COO)2.2H2O 98%] and sodium hydroxide [NaOH 98%] were used. All the commercially purchased materials were used as received without further purification.
ZnO nanoparticles synthesis
Hydrothermal technique has the ability to prepare nanomaterials with high quality and low cost. In this work, the ZnO nanoparticles were synthesized by a modified hydrothermal method [1,[21][22]. The reactions involved in the synthesis process of ZnO nanoparticles can be described through the following [1]:
Zn(CH3COO)2.2H2O + 2NaOH → Zn(OH)2 + 2CH3COONa +2H2O (1) Zn(OH)2 + 2H2O = Zn 2+ + 2OH -+ 2H2O = [Zn(OH)4] 2 (2) [Zn(OH)4] 2-↔ ZnO2 -2 +2H2O (3) ZnO2 -2 +2H2 O ↔ZnO + 2OH −(4)
The procedure of the formation of ZnO nanoparticles includes two main steps. Firstly, is the nucleation (generation of ZnO nuclei), and secondly is the grain growth (ZnO crystal growth) [1,[21][22]. In equation (1)
Characterization
X-ray diffraction patterns were recorded for the prepared nanoparticles to determine the crystal phase and estimate the crystallite size. The crystalline structures of the synthesized powders were analyzed by X-ray diffractometry (X'Pert PRO, PANalytical, Netherlands) using Cu-Kα radiation in the angular region of (20 o -70 o ) at 40 kV. The crystallite size (D) and the lattice strain were estimated using the Scherer's equation and Williamson-Hall method. The elemental analysis was performed by energy-dispersive X-ray (EDX) instrument (JEOL, JEMA 2100-Japan) at 10 kV. The morphology of the obtained ZnO nanoparticles was characterized with high resolution transmission electron microscope (HR-TEM), (JEOL, JEMA 2100-Japan), performed at 200 kV. Fourier transform infra-red (FTIR) spectra was carried out using (FTIR Perkin Elmer-Spectrum One) at range 400-4000 cm -1 with a resolution of 4 cm -1 at room temperature. For the optical measurements, JASCO 6700 UV-VIS-NIR spectrophotometer was used in UV-visible absorption analysis. Fluorescence measurements were taken under ambient conditions and at room temperature by using JASCO 8600 fluorescence spectrophotometer (λexc=365 nm). Thermal analysis was done using LINSEIS STA PT-1000 to study the thermal stability of ZnO nanoparticles. Approximately, 25 mg of the samples were used and the heating rate was 10 °C/min up to 800 °C. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 and intense peaks observed from XRD patterns (Figs.1a, b) confirm that the prepared ZnO nanoparticles is of high crystalline nature with hexagonal phase. The average crystallite size, D, has been obtained from the main diffraction peak along the (101) plane using the Debye-Scherrer formula [1] as follows: D = 0.9 λ /β cosθ (5) where, λ is the wavelength of X-ray used (1.54060 Å), β is the angular peak width at half maximum in radians and θ is Bragg's diffraction angle. From the recorded XRD pattern, the synthesized ZnO nanoparticles are listed as wurtzite hexagonal closely packed structure and its lattice constants a and c were determined from the following equation using the interplanar distance d and (hkl) values of the XRD profile [23], Table 1 shows the calculated lattice parameters, which are matched to those available in standard JCPDS data (No. . To estimate the crystallite size and the lattice strain, an inspection of the shape of the diffraction peaks was performed using Williamson-Hall (WH) method (Equation 7). WH calculations procedure is carried out for every peak obtained in the XRD spectra of the ZnO nanoparticles. The full width at half maximum (FWHM), β, is related to the crystallite size, D, and the strain, ε, by equation 7: β* =d*ε + 1/D (7) where β*= β cos θ /λ and d*= 4 sinθ/λ; θ is the Bragg angle and λ is the wavelength used. From Eq. (7), the intercept and the slope of the plot of β*against d* give 1/D and the strain [24][25], respectively. Table 1 shows crystallite size values for the prepared samples estimated by Scherer and Williamson-Hall methods. From the XRD calculations, it is obvious that the average crystallite size slightly increases with the increase of the reaction time and synthesis temperature (see Fig. 2a, b). This may be due to increasing of nucleation and growth rate of nanoparticles [23]. From table 1, it is clear that the crystallite size calculated from XRD data using Debye-Scherrer equation is smaller than crystallite size determined from Williamson-Hall method. This may be due to the fact that the Scherrer method actually measures the coherence length of the X-rays, any crystal imperfections will cause the calculated size to be smaller than the true size but in WH method the microstrain effect was taken into consideration [26]. The dislocation density (concentration of defects and vacancies in the crystal), S, can be determined from the following equation by using the crystallite size (D) [23]: S = 1/D 2 (8) From Table 1, it can be seen that S changes with different values of time and temperature, which means that the lattice imperfection decreases with particle size. Also, the micro-strain of the samples changes with time and temperature, which may be attributed to the change in microstructure, size, shape and defects of the particles [27]. Figure 3 (a, b) shows the EDX spectrum of ZnO nanoparticles synthesized by hydrothermal method with different reaction times and different temperatures. Similar spectra were obtained for all the prepared samples, only two spectra are shown here (S1 and S8). The strong peaks shown in the spectra, referred to zinc and oxygen elements, indicate that the synthesized nanoparticles have Zn and O elements only.
Results and Discussion
X-ray diffraction (XRD) studies
) 6 ( 2 2 2 2 2 3 4 2 1 c l a l hk h d
Energy-dispersive X-Ray (EDX)
Transmission electron microscope analysis
HR-TEM was carried out to investigate the shape and size of the synthesized ZnO nanoparticles. Figure 4 (S1-S10) shows the HR-TEM images of prepared ZnO nanoparticles with different reaction times 8, 12, 16, 20 and 24 hrs and reaction temperatures 100, 125, 150, 175, and 200 o C. The reaction time and synthesis temperature affect the shape and size of the obtained ZnO nanoparticles. The particles with spherical-like shape were observed in S1 and S6 only. With increasing the reaction time and temperature spherical-like and rods shapes of ZnO nanoparticles were obtained due to the increase of the growth rate. As the reaction time and temperature increased, nearly all the ZnO nanoparticles appeared in clusters of nanorods shape due to smaller nanoparticles coalescing and forming larger particles, i.e. clusters. From the HR-TEM images the average size of the ZnO nanoparticles is in the range of 30-40 nm, which agree with the size determined from XRD data.
Fourier transform infra-red (FT-IR) analysis Figures 5 (a) and 5 (b) display results of FT-IR analysis for prepared ZnO nanoparticles at different times and temperatures, respectively. A group of absorption
peaks observed in the range of 4,000 to 400 cm -1 represents the vibration modes of contaminations such as hydroxyl, carboxyl found in the prepared nanoparticles. The absorption bands at (3433-3413 cm -1 ) represent O-H stretching vibration. Peaks recorded between (1,626 and 1,581 cm -1 ) are probably from C=O band. The absorption peaks at (1,410-1,435 cm -1 ) represent the carboxylate group (COO -). The peaks around (1,021-1,028 cm -1 ) confirm the stretching vibration of C-O attributed to zinc acetate. In the infra-red region, characteristic Zn-O stretching mode was found between (418 and 571 cm -1 ). The difference in wavenumber may be attributed to the difference in particle sizes of prepared samples [7,23,[28][29]. Figures 6 (a) and 6 (b) show the optical absorption and transmittance spectra of the prepared samples at near normal incidence over a spectral ranging between 200 and 800 nm for different times and temperatures, respectively. The direct optical band gap with direct transition can be calculated using the relation: αhγ = B (hγ -Eg) 1/2 (9) where hγ is the photon energy and B is a constant that depends on the transition probability, α is the absorption coefficient and Eg is the optical band gap. As shown in Figure 7 (a, b) the energy gap (Eg) can be estimated from the plot hγ against (αhγ) 2 .
Optical properties of ZnO nanoparticles
The values of Eg are in the range (2.90-3.62 eV) and depend the reaction times and reaction temperatures ( Table 2). These obtained values are different from that of the bulk ZnO (3.37eV). This blue shift may be attributed to quantum confinement effects in the prepared zinc oxide samples [20,23] . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 From Fig.7, it can be noticed that with increasing the reaction time and reaction temperature, the band gap value decreases due to the increase of the crystallite size. This confirms that the above behavior may be due to increasing of nucleation and growth rate of nanoparticles [23]. Figures 8(a) and 8(b) show fluorescence spectra of ZnO nanoparticles synthesized under different reaction times and temperatures, respectively. Each curve reveals that the PL intensity decreases with reaction times and temperatures. The observed dominant narrow UV emission band peak at 417 nm originates from the near-bandedge transition and its intensity decreases with increasing particle size of ZnO nanoparticles. The tail-band violet emission at 445 nm is attributed to the presence of zinc interstitials (Zni). Exciton recombination between the electrons at the zinc interstitials and valence band holes leads to this violet emission. This type of violet emission band was also observed by others [23,30]. The broad-band green emission at 530 nm is assigned to the recombination of electrons trapped at vacancy defects [31][32][33]. The fluorescence spectrum confirms that the type of emissions from the ZnO nanoparticles, whether UV (or) violet is affected by the time and temperature of the reaction. In addition, the violet and green bands confirm that the samples contain ZnO nanoparticles [30,[34][35]. Figure 9 (a, b) shows the thermogravimetric (TG) analysis of ZnO nanoparticles. From the figure, it can be seen that there is no significant weight loss observed for all samples (approximately 10%). This may be due to the evaporation of water and the removal and decomposition of organic groups found in the samples during the hydrothermally synthesis [36][37][38][39]. Furthermore, no significant loss of weight was observed from the samples above 750 o C. Figures 10(a) and 10(b) show the differential scanning calorimetry (DSC) of ZnO nanoparticles under different reaction times and temperatures, respectively. Two peaks are observed, the first one occurs at around 150 o C and is weak. This peak can be attributed to an activation energy involving an endothermic reaction. The second peak around 400 o C is a broad, which suggests an exothermic reaction that may be due to the burn-out of organic composition. It is worth pointing out that both peaks are due to change of phases at those temperatures [36][37][38][39].
Fluorescence Spectra of ZnO Nanoparticles
Thermal analysis spectra
Conclusions
ZnO nanoparticles have been synthesized by using modified hydrothermal method at different reaction times and synthesis temperatures. The results confirmed that reaction time and synthesis temperature have an influence in the structure and optical properties of ZnO nanoparticles. XRD studies established the presence of the wurtzite hexagonal structure, and showed that the average crystallite size slightly increases with the increase of the reaction time and synthesis temperature. HR-TEM images showed that the average size of the ZnO nanoparticles is in the range of 30-40 nm, which is in a good agreement with the size determined by XRD. UV-Vis spectra indicate that with increasing the reaction time and reaction temperature, the band gap value decreases due to the increase of the crystallite size. The fluorescence spectra confirm that the type of emissions from the ZnO nanoparticles, is affected by the time and temperature of the reaction. TG analysis of the ZnO nanoparticles showed that no significant loss of weight was observed above 750 oC for all prepared samples. DSC of ZnO samples under different times and temperatures indicates endothermic reactions and exothermic reactions which are due to change of phases at those temperatures. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
Figure 1 (
1a, b) illustrates a typical XRD spectrum of ZnO nanoparticles synthesized by hydrothermal method under different times 8, 12, 16, 20 and 24 hrs(Fig.1a), and different reaction temperatures 100, 125, 150, 175, and 200 o C(Fig.1b). The XRD spectra indicate that the ZnO nanoparticles have a hexagonal structure, with lattice constants (a = b = 0.3251 nm) and (c = 0.5212 nm) as in standard JCPDS data (No.. The XRD pattern does not contain any particular peaks other than ZnO peaks which means that the dominant phase is hexagonal ZnO nanoparticles. Sharp
65 FiguresFig
65. 1a XRD spectrum of ZnO nanoparticles under different reaction times 8, 12, 16, 20 and 24 hrs.
Fig. 1b Fig. 2 :
1b2XRD spectrum of ZnO nanoparticles under different synthesis temperatures 100, 125, 150, 175, and 200 o C. Crystallite size as a function of (a) reaction time and (b) synthesis temperature.
FigureFig. 3
3EDX spectra of ZnO nanoparticles prepared at (a) 8 hours and (b) 150 o C.Fig. 4 HR-TEM images of prepared ZnO nanoparticles synthesized atvarious reaction times (S1-S5) and various temperatures (S6-S10).
Fig. 5 FT
5-IR spectra of ZnO nanoparticles synthesized at (a) various reaction times and (b) various temperatures.Fig. 6a Absorbance and transmittance spectra of ZnO nanoparticles synthesized at different times.Fig. 6b Absorbance and transmittance spectra of ZnO nanoparticles synthesized at different temperatures. Fig. 7a Plots of hγ against (αhγ) 2 of ZnO nanoparticles synthesized at different reaction times. Fig. 7b Plots of hγ against (αhγ) 2 of ZnO nanoparticles synthesized at different temperatures. Fig. 8a Fluorescence spectra of the ZnO nanoparticles synthesized at different times. Fig. 8b Fluorescence spectra of the ZnO nanoparticles synthesized at different temperatures. 6 Fig. 9a TG curves of ZnO nanoparticles synthesized at different times. Fig. 9b TG curves of ZnO nanoparticles synthesized at different temperature 7 Fig. 10a DSC of ZnO nanoparticles synthesized at different times. Fig. 10b DSC of ZnO nanoparticles synthesized at different temperature Tables
Table 1 .
1The characteristics of the ZnO nanoparticles synthesized at various time and temperature values.Table 2. Band gap values estimated for different reaction times and temperatures.NO. Factor
2θ(101),
( o )
FWHM
, (rad),
(10 -2 )
D (nm)
d,
(nm)
a
(nm)
c,
(nm)
S
(10 -3 )
ε, (10 -3 )
Scherer
WH
S1
8 h
36.285
0. 4662
31.30
48.14 0.2475 0.3249 0.5205 1.02
1.1075
S2
12 h
36.307
0. 4698
31.06
61.1
0.2475 0.3249 0.5205 1.04
1.1161
S3
16 h
36.288
0.4388
33.25
44.7
0.2475 0.3249 0.5205 0.90
1.0424
S4
20 h
36.329
0.3812
38.28
48.56 0.2475 0.3249 0.5205 0.68
0.9055
S5
24 h
36.282
0.4168
35.01
48.76 0.2475 0.3249 0.5205 0.82
0.9902
S6
100 o C 36.264
0.5402
27.02
31.68 0.2475 0.3249 0.5205 1.37
1.2831
S7
125 o C 36.256
0.5248
27.80
34.48 0.2476 0.3250 0.5207 1.29
1.2468
S8
150 o C 36.264
0.4388
33.12
44.27 0.2475 0.3249 0.5205 0.90
1.0424
S9
175 o C 36.256
0.4897
29.79
44.02 0.2476 0.3250 0.5207 1.13
1.1635
S10
200 o C 36.265
0.4157
35.10
50.99 0.2475 0.3249 0.5205 0.81
0.9875
Time, hrs.
Eg, eV
Temperature, o C
Eg, eV
8
3.62
100
3.60
12
3.40
125
3.38
15
3.26
150
3.28
20
3.13
175
3.18
24
2.90
200
2.91
ACKNOWLEDGEMENTThe authors would like to express their gratitude to Al-Azhar University and South Valley University for providing administrative and technical support.
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. J N Hasnidawani, H N Azlina, H Norita, N N Bonnia, S Ratim, E S Ali, Synthesis of ZnO Nanostructures Using Sol-Gel. 19Procedia ChemistryJ.N. Hasnidawani, H.N. Azlina, H. Norita, N.N. Bonnia, S. Ratim, E.S. Ali, Synthesis of ZnO Nanostructures Using Sol-Gel, Procedia Chemistry 19 (2016) 211-216.
Facile synthesis of nano-sized ZnO by direct precipitation method. S Bagheri, K G Chandrappa, S B Hamid, Der Pharma Chemica. 5S. Bagheri, K.G. Chandrappa, S. B. Abd Hamid, Facile synthesis of nano-sized ZnO by direct precipitation method, Der Pharma Chemica, 5 (2013) 265-270.
Synthesis and Characterization of ZnO Nanoparticles via Precipitation Method: Effect of Annealing Temperature on Particle Size. N A Salahuddin, M El-Kemary, E M Ibrahim, Nanoscience and Nanotechnology. 5N.A. Salahuddin, M. El-Kemary, E.M. Ibrahim, Synthesis and Characterization of ZnO Nanoparticles via Precipitation Method: Effect of Annealing Temperature on Particle Size, Nanoscience and Nanotechnology, 5 (2015) 82-88.
Sumetha Suwanboon, Structural, optical and photocatalytic properties of MgO/ZnO nanocomposites prepared by a hydrothermal method. Pongsaton Sarunya Klubnuan, Amornpitoksuk, Materials Science in Semiconductor Processing. 39Sarunya Klubnuan, Pongsaton Amornpitoksuk, Sumetha Suwanboon, Structural, optical and photocatalytic properties of MgO/ZnO nanocomposites prepared by a hydrothermal method, Materials Science in Semiconductor Processing 39 (2015) 515-520.
| Differential dose-dependent effects of zinc oxide nanoparticles on oxidative stress-mediated pancreatic β-cell death. | 3 Toxic Effects and Mode of Action Whereas metallic zinc is practically non-toxic, inhalation of zinc oxide during smelt- ing or welding can cause acute intoxication (metal fume fever). | Zirconia (ZrO2) is one of the widely used metal oxides for potential bio-applications such as biosensors, cancer therapy, implants, and dentistry due to its high mechanical strength and less toxicity. Because of their widespread applications, the potential exposure to these nanoparticles (NPs) has increased, which has attracted extensive attention. Thus, it is urgent to investigate the toxicological profile of ZrO2 NPs. Titanium dioxide (TiO2) is another extensively used nanomaterials which are known to be weakly toxic. In this study, TiO2 NPs were served as control to evaluate the biocompatibility of ZrO2 NPs. We detected the cytotoxicity of TiO2 and ZrO2 NPs in osteoblast-like 3T3-E1 cells and found that reactive oxygen species (ROS) played a crucial role in the TiO2 and ZrO2 NP-induced cytotoxicity with concentration-dependent manner. We also showed TiO2 and ZrO2 NPs could induce apoptosis and morphology changes after culturing with 3T3-E1 cells at high concentrations. Moreover, TiO2 and ZrO2 NPs at high concentrations could inhibit cell osteogenic differentiation, compared to those at low concentrations. In conclusion, TiO2 and ZrO2 NPs could induce cytotoxic responses in vitro in a concentration-dependent manner, which may also affect osteogenesis; ZrO2 NPs showed more potent toxic effects than TiO2 NPs. | Our study was framed to evaluate the acute toxicity, behavioural and heametalogical effects of ZnO NPs on freshwater fish Oreochromis mossambicus. ZnO NPs characterized by FTIR and UV Spectroscopy. Various behaviour patterns were studied in 30, 50 and 70ppm ZnO NPs concentration. The actue toxicity (96hrs LC 50 ) of ZnO NPs was observed between 100-110ppm. Significantly decreased number of Total Red cell count (RBC), haemaglobin (Hb), Haematocrit (Ht) reflects changes in red blood indicies such as MCV, MCH, MCHC and oxygen carrying capacity. Decreased leucocytes and differential count differences observred in ZnO NPs exposed groups. As a novel attempt, our study showed the impact of ZnO nanoparticles in Acute toxicity and Haematological parameters of freshwater fish O. mossambicus. | 1,999,743 | Metallic nanoparticles (NPs) have potential applications in industry and medicine, but they also have the potential to cause many chronic pulmonary diseases. Mechanisms for their cytotoxicity, glucose and energy metabolism responses need to be fully explained in lung epithelial cells after treatment with metallic nanoparticles. In our study, two different metallic nanoparticles (Fe2 O3 and ZnO) and two cell-based assays (BEAS-2B and A549 cell lines) were used. Our findings demonstrate that ZnO nanoparticles, but not Fe2 O3 nanoparticles, induce cell cycle arrest, cell apoptosis, reactive oxygen species (ROS) production, mitochondrial dysfunction and glucose metabolism perturbation, which are responsible for cytotoxicity. These results also suggest that the glucose metabolism and bioenergetics had a great potential in evaluating the cytotoxicity and thus were very helpful in understanding their underlying molecular mechanisms. | Metal nanoparticles are of increasing interest with respect to radiosensitization. The physical mechanisms of dose enhancement from X-rays interacting with nanoparticles has been well described theoretically, however have been insufficient in adequately explaining radiobiological response. Further confounding experimental observations is examples of radioprotection. Consequently, other mechanisms have gained increasing attention, especially via enhanced production of reactive oxygen species (ROS) leading to chemical-based mechanisms. Despite the large number of variables differing between published studies, a consensus identifies ROS-related mechanisms as being of significant importance. Understanding the structure-function relationship in enhancing ROS generation will guide optimization of metal nanoparticle radiosensitisers with respect to maximizing oxidative damage to cancer cells. This review highlights the physico-chemical mechanisms involved in enhancing ROS, commonly used assays and experimental considerations, variables involved in enhancing ROS generation and damage to cells and identifies current gaps in the literature that deserve attention. ROS generation and the radiobiological effects are shown to be highly complex with respect to nanoparticle physico-chemical properties and their fate within cells. There are a number of potential biological targets impacted by enhancing, or scavenging, ROS which add significant complexity to directly linking specific nanoparticle properties to a macroscale radiobiological result. | With the rapid development of nanotechnology, much has been anticipated with copper oxide nanoparticles (CuO NP) due to their extensive industrial and commercial application. However, it has raised concern over the environmental safety and human health effects. In this study, CuO nanoparticles were synthesized using the green method with floral extract of Calotropis gigantea and characterized by standard physiochemical techniques like DLS, Zeta potential determination, UV-Visible Spectroscopy, XRD, FTIR, FESEM, and TEM. Mechanistic cytotoxicity studies were performed using experimental and computational assays including morphological analysis, hatching, and viability rate analysis along with ROS and apoptosis analysis. Physiochemical characterization of CuO NP determined the size and zeta potential of synthesized nanoparticles to be 30 ± 09 nm to 40 ± 2 nm and −38 mV ± 12 mV respectively. Cytotoxicity evaluation with Zebrafish revealed malfunctioned organ development with differential viability and hatching rate at 48 hpf and 72 hpf with LC50 of 175 ± 10 mg/l. Computational analysis depicted the influential role of CuO nanoparticles on zebrafish embryo's he1a, sod1 and p53 functional expression through hydrophobic and hydrogen bond interaction with amino acid residues.Study demonstrated valuable information of cytotoxic impact which can be influential in further studies of their eco-toxicological effects.Copper oxide nanoparticles have long been used as an antimicrobial agent in medical, cosmetics industry and appliances for public use 1 . The increased demands with this utility have instigated a large production and use of these nanoparticles day by day. This bulk production and usage have raised the concern over the toxicity of these nanomaterials on the ecosystem as well as on human health. Concerns over the toxic effect of CuO nanoparticles usage has drawn a specific attraction of toxicology researchers in last few years. Many studies have been reported the cytotoxicity and genotoxicity of CuO nanoparticles through in vitro and in vivo investigation in mammalian cell line and animal models. In vitro studies have reported the cytotoxicity and genotoxicity of CuO nanoparticles in lung epithelial, peripheral blood and cancer cell lines 2-5 . In vivo studies have also revealed the genotoxic effects of neoplastic lesions, DNA alteration and DNA strand break in mouse 6,7 . Used CuO nanoparticles released in the aquatic environment also cause toxicity to fishes and aquatic animals. So, synthesis of eco-friendly biocompatible CuO nanoparticles has become the urgent need of the hour with a proper investigation of their biological properties like cytotoxicity. | The human lung adenocarcinoma epithelial (A549) cells and the human embryo lung (HEL 12469) cells were used to investigate the uptake and cytotoxicity of magnetite nanoparticles (MNPs) with different chemically modified surfaces. MNPs uptake was an energy-dependent process substantially affected by the serum concentration in the culture medium. Internalized MNPs localized in vesicle-bound aggregates were observed in the cytoplasm, none in the nucleus or in mitochondria. All MNPs induced a dose- and time-dependent increase in cytotoxicity in both human lung cell lines. The cytotoxicity of MNPs increased proportionally with the particle size. Since the cytotoxicity of MNPs was nearly identical when the doses were equalized based on particle surface area, we suppose that the particle surface area rather than the surface modifications per se underlay the cytotoxicity of MNPs. In general, higher internalized amount of MNPs was found in HEL 12469 cells compared with A549 cells. Accordingly, the viability of the human embryo lung cells was reduced more substantially than that of the adenocarcinoma lung cells. The weak MNPs uptake into A549 cells might be of biomedical relevance in cases where MNPs should be used as nanocarriers for targeted drug delivery in tumor tissue derived from alveolar epithelial cells. | A rapid and ecofriendly fabrication of metal oxide nanoparticles using biogenic sources is the current trend being used to replace the toxic chemical method. The present study was carried out to synthesize magnesium oxide nanoparticles (MgONPs) using the marine brown algae Sargassum wighitii as the reducing and capping agent. The as-prepared MgONPs were characterized by spectroscopic and microscopic analyses. UV-visible spectrum of the MgONPs showed a sharp absorption peak at 322 nm. X- ray diffraction analysis illustrated that the MgONPs were crystalline in nature with a face-centered cubic structure. Presence of magnesium and oxygen were further confirmed by EDX profile. FTIR analysis showed the presence of functional groups specific for sulfated polysaccharides, which might be responsible for the synthesis of MgONPs. Zeta potential and dynamic light scattering analysis illustrated that the MgONPs were highly stable at 19.8 mV with an average size of 68.06 nm. MgONPs showed potent antibacterial activity and antifungal activities against human pathogens. Photocatalytic activity of MgONPs was witnessed by the quick degradation of the organic dye methylene blue on exposure to both sunlight and UV irradiation. MgONPs showed significant cytotoxicity against the lung cancer cell lines A549 in a dose dependent manner with the IC50 value of 37.5 ± 0.34 μg/ml. Safety evaluation using peripheral blood mononuclear cells (PBMCs) illustrated the MgONPs to be non-toxic in nature. Overall, the results concluded that the MgONPs generated using marine algae have exhibited scope for multifaceted biological applications. | Oxidative Stress Induced by CuO Nanoparticles (CuO NPs) to Human Hepatocarcinoma (HepG2) Cells | Anthropic nanoparticles (NP) are increasingly produced and emitted, with accompanying concerns for human health. Currently there is no global understanding as to the exact mechanistics of NP toxicity, as the traditional nanotoxicological approaches only provide a restricted overview. To address this issue, we performed an in-depth transcriptomic analysis of human macrophages exposed to a panel of welding-related metal oxide NP that we previously identified in welders lungs (Fe 2 O 3 , Fe 3 O 4 , MnFe 2 O 4 and CrOOH NP). Utilizing the specified analysis criteria (|fold change| ≥1.5, p ≤ 0.001), a total of 2164 genes were identified to be differentially expressed after THP-1 macrophage exposure to the different NP. Performing Gene Ontology enrichment analysis, for cellular content, biological processes and Swiss-Prot/Protein Information Resource keywords the data show for the first time a profound modification of gene differential expression in response to the different NP, among which MnFe 2 O 4 NP were the most potent to induce THP-1 macrophage activation. The transcriptomic analysis utilized in the study, provides novel insights into mechanisms that could contribute to NP-induced adverse effects and support the need for widened approaches to supplement existing knowledge of the processes underlying NP toxicity which would have not been possible using traditional nanotoxicological studies.Anthropic nanoparticles (NP) are increasingly produced and emitted, not only due to their unique desirable properties, but also due to their unintentional release (i.e. during automotive combustion, in tobacco smoke or welding fumes). As such, anthropic NP represent a significant and ever-increasing proportion of particulate atmospheric pollution. Considering the various adverse health effects that have long been associated with atmospheric pollution in the general population as well as in compromised individuals 1-5 , this increasing exposure to anthropic NP is associated with concerns for human health. This is particularly true for carbonaceous NP (i.e. carbon nanotubes and carbon black) as well as metallic NP (i.e. iron, titanium, manganese, chromium oxides), that both highly contribute to anthropic NP pollution 6 .A large body of data from in vivo literature demonstrates that NP can exert adverse effects after pulmonary administration, such as granuloma formation and/or development of lung fibrosis 7 . The specific NP physico-chemical characteristics such as size, elemental composition, surface reactivity, shape, solubility represent major determinants of these potential adverse effects. In general, an inflammatory response, oxidative stress, DNA damages or cell death manifested as necrosis or apoptosis are the most studied mechanisms of toxicity, and as such are classically proposed to be responsible or at least contribute to NP-mediated adverse effects 7 . However, it is also generally acknowledged that the exact mechanistic of NP toxicity is yet not fully elucidated, partly because traditional nanotoxicological approaches only provide a restricted view of what occurs after NP exposure. In the last few years, transcriptomic analysis has allowed for a more comprehensive insight into how altered expression of genetic variants can contribute to toxicological outcomes and complex diseases. Yet, the Published: xx xx xxxx OPEN www.nature.com/scientificreports/ 2 Scientific RepORts | (2018) 8:8554 | | Towards predicting the lung fibrogenic activity of nanomaterials: experimental validation of an in vitro fibroblast proliferation assay | Background:Recently, nanomaterials have moved into biological and medicinal implementations like cancer therapy. Therefore, before clinical trials, their binding to plasma proteins like human serum albumin (HSA) and their cytotoxic effects against normal and cancer cell lines should be addressed. Methods: Herein, the interaction of magnesium oxide nanoparticles (MgO NPs) with HSA was studied by means of fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and docking studies. Afterwards, the cytotoxic impacts of MgO NPs on human leukemia cell line (K562) and peripheral blood mononucleated cells (PBMCs) were evaluated by MTT and flow cytometry assays to quantify reactive oxygen species (ROS) generation and apoptosis. Results: It was demonstrated that MgO NPs spontaneously form a static complex with HSA molecules through hydrophobic interactions. Docking study based on the size of NPs demonstrated that different linkages can be established between MgO NPs and HSA. The CD investigation explored that MgO NPs did not alter the secondary structure of HSA. Cellular studies revealed that MgO NPs induced cytotoxicity against K562 cell lines, whereas no adverse effects were detected on PBMCs up to optimum applied concentration of MgO NPs. It was exhibited that ROS production mediated by IC50 concentrations of MgO NPs caused apoptosis-associated cell death. The pre-incubation of K562 with ROS scavenger (curcumin) inhibited the impact of MgO NPs -based apoptosis on cell fate, revealing the upstream effect of ROS in our system. Conclusion: In summary, MgO NPs may exhibit strong plasma distribution and mediate apoptosis by ROS induction in the cancer cell lines. These data demonstrate a safe aspect of MgO NPs on the proteins and normal cells and their application as a distinctive therapeutic approach in the cancer treatment. |
1,999,744 | what is the larva of anthrax called | What is the most commen type of anthrax? | What are the most common anthrax? | Anthrax (fly) Anthrax is a genus of bombyliid flies, commonly known as "bee-flies" due to their resemblance to bees. Most are dull black flies, and are usually small to medium in size, , and many species have striking wing patterns. "Anthrax" is a very large genus. While worldwide in distribution, most species are from the Palaearctic and Afrotropic regions. The genus includes species parasitic on tiger beetles – an unusual trait among the bee-flies. "A. anthrax" larvae parasitize bees. Many North American species parasitize solitary wasps. The type species is "Musca morio" Linnaeus, 1758, later found to be a misidentification | Railroad worm A railroad worm is a larva or larviform female adult of a beetle of the genus Phrixothrix in the family Phengodidae, characterized by the possession of two different colors of bioluminescence. It has the appearance of a caterpillar. The eleven pairs of luminescent organs on their second thoracic segment through their ninth abdominal segment can glow yellowish-green, while the pair on their head can glow red; this is probably due to different luciferases in their bodies, as the reaction substrate, called luciferin, is the same. The "railroad worm" name arises because these glowing spots along the body resemble | The mangos, Anthracothorax, are a genus of hummingbirds in the subfamily Trochilinae native to the Neotropics.
The genus Anthracothorax was introduced by the German zoologist Friedrich Boie in 1831. The type species was subsequently designated as the green-throated mango (Anthracothorax viridigula). The generic name combines the Ancient Greek anthrax meaning "coal" (i.e. black) with thōrax meaning "chest".
A molecular phylogenetic study published in 2014 found that Anthracothorax was paraphyletic with respect to Eulampis.
Species
The genus contains seven species:
References
Bird genera
Taxonomy articles created by Polbot | Echinococcus spp. Tapeworms in North America | their hosts causing an infection, which often results in death because the immune system was weakened by scabies before. The high host specificity of the mites is held responsible for the fact that mostly even-toed ungulates struggled with these consequences. In late 1950s the last foci of infection were reported in semi-domesticated reindeers after which no greater incidences were observed. Anthrax mite The Anthrax mite ("Sarcoptes anthracis") is a pathogenic mite and an intermediate host of anthrax. "Sarcoptes anthracis" was classified by Dmitri Ivanovsky in 1901 after first occurrences of infection on Asian Tufted Deers. The parasitic itch mite burrows | Polistes biglumis wasp. Parasite queens have levels of epicuticular hydrocarbons key to recognition that are three to four times less than in host wasps, which facilitates a weaker signal that allows them to insinuate themselves into host colonies. As time progresses, the parasite queen can camouflage her odor as a host wasp; at the point of emergence for the workers, the parasite queen is indistinguishable from the host queen. The adult parasitic offspring have no such mechanism for deception and they have unsaturated epicuticular hydrocarbons specific to their species that do not occur in the host species. However, the different odors of | 1,999,744 | Anthrax anthrax Anthrax anthrax, is a species of fly in the family "Bombyliidae" but unlike for example "Bombylius major" this species does not mimic a bee or bumblebee. The eggs are flicked by the adult female toward the entrance of the nests of mason bees. After hatching, the larvae find their way into the nests to feed on the bee larva. "Anthrax anthrax" can be found in May to August throughout mainland Europe, but probably does not occur in Britain. In the Netherlands "Anthrax anthrax" is a common visitor of insect hotels. "Anthrax anthrax" is a fairly large fly, the | what type of fly is anthrax a type of | What is the most common kind of anthrax? | what is the scientific name for anthrax mite | What is the most comen anthrax? | Anthracothorax | Is anthrax generally considered to be contagius? | Detection and Identification of Bacillus anthracis: From Conventional to Molecular Microbiology Methods | What does the bacterium Bacillus Anthracis do? |
1,999,745 | Seeking advice. Bought a house in Naperville almost three years ago. Unable to replace my deck due to City owned Utility. | Can anyone speak on what would happen to us if our insurance agent sent an inspector before our annual renewal, and he determined that the rear porches are a significant risk? What do I have to worry about as an owner, and what can I do to get ahead of this so that it doesn't become a catastrophic issue?
Background: We have a triple decker in Boston. It is 110 years old. The rear porches looks like it's original construction. Typical of old Boston triple-deckers, it is old wood with lead paint creating a porch on the rear of floors two and three.
The entire porch has been reinforced at least once and is still sagged down at least a foot. It has bowed out several inches and really needs to be replaced completely. I'd like to pay money and have it done immediately, but the other owners are unwilling to pay up-front, and are hoping to do it with condo fees far down the line. I want to understand the financial risks to not fixing the porch for the next 7-10 years.
Thanks for any replies. | TL;DR - I’m a beginner DIYer. Am I crazy for wanting to purchase a 90 year old home on close to an acre of land? Are there others out there that have gone through something similar? If so, what were your experiences?
The properties my wife and I have owned were new build (2007 and 2018) townhomes. Because they’ve been new, there wasn’t much of a need for home improvement. Before this year, I didn’t do much more than install ceiling fans or recaulk a bathtub.
During the pandemic, to keep myself busy I wanted to get into woodworking. Before jumping into that, I felt like I wanted to finish the garage (which was taped and had one coat of mud). I didn’t have much of a reason other than, I felt like it’d make it more comfortable. Well, before sanding and mudding, I decided that I should add another outlet and add better lighting. I drew up an electrical plan, ripped out a bunch of drywall (far more than I needed to), replaced it and finally got it all done. It took me about four months, mostly one day a weekend for four to five hours, with some help from friends/family.
So that’s it. That’s everything I’ve tackled from a DIY standpoint. I mostly enjoyed the work and learned a lot. But there were times where I felt like I just wanted to be done with it.
Now, my wife and I are considering finding a new home, one with a yard for our couch potato greyhounds to run around in. We came across a property that’s about 90 years old. We toured the property, a lot of it is original with some minor updates. There are concerns
- Potential water damage
- Doorway sagging around that potential water damage
- Furnace appears old. Information is painted over
- Water heater appears old
- Potential structural crack
- Two parts of the house have close to a flat roof, where you can see where water has pooled. One of these is above where there was potential water damage.
- Electrical appears old.
There’s probably more. We’ve only toured the home - if we do get more serious we’ll have an inspection done and structural engineer come out to look at it. All of this is uncharted territory for us. Normally I’d have moved on and forgotten about it.
But there’s something I can’t shake about this place (hence the middle of the night post about it). Even with all these problems it’s stuck in my mind. There’s room to grow a large vegetable garden (enough for us and then some), raise chickens, have a workshop, build a nice carriage house for friends/family. All of this I’d like to learn and do as much as practical - more from I wanting to learn than saving money (but that doesn’t hurt). I could see my wife and I living here until our dogs finally put us in a home. I’m not looking to flip the property and know that it will likely take tens of years to get everything done.
The house is livable in its current condition. I also know that living in a house that’s under construction is a different beast. I’d need to write it all down to make sure it’s even possible, but the goal would be to work in sections, allowing us to move stuff around or not use certain rooms while it’s being worked on. If anyone has recommendations or if this is a fool’s errand, I’d appreciate it.
The new mortgage would be higher than our current mortgage but not drastically. We live comfortably, but are not in the position to consider scraping the house. I know structural issues can be expensive, but assuming we’d have some time to plan/prepare, it’s something we’d be able account for.
So... I think that’s everything. There’s a lot of information here. I hope it’s mostly relevant and isn’t too scatter-brained. Is this something that is reasonably possible, or will we die broke with a half finished house and be at the house’s beck and call, unable to enjoy anything else in life? I’ve done a small amount of Googling around buying older homes (still need to do more), but any recommendations/experiences/things I missed are be appreciated. | When you are hunting for a new apartment, check out the City of Milwaukee's Property Registry. Here you can find out information about the citations from the Department of Neighborhood Services, service requests from past tenants, and information about the owner.
1) The DNS citations will show you how quickly your potential landlord responds to broken things. Or if they respond at all. If there is a long history of citations from DNS, they are likely not a responsive landlord. Even if the complaints were closed, it shows that they are waiting for the city to become involved before they tend to their property.
2) Service requests will show you what has been wrong with the apartment in the past. Ask the potential landlord about some of these things. If they deny them, or try to hide something, they are probably not the best landlord.
3) You can search the potential landlord on CCAP and find out their history with small claims court and whether or not they pursue excessive damages relating to security deposits. If they have a large history with evictions, they are probably not the best landlord.
4) You can see what permits have been pulled for work on the property. If they claim a major remodel has occurred that requires a licensed worker to pull a permit, and no permits have been pulled, then don't live there.
5) Overall, it's good to know more about the history of the unit you are renting.
If you have an unresponsive landlord, the DNS complaint hotline is 414-286-2268. | Hello everyone,
I currently own a townhouse (technically condo) and am considering selling while values are up but would like some advice. I'm 25, make $72k/yr, and am currently single with no debt besides the mortgage.
I paid about $200k for the townhouse 2 years ago, currently owe $183k on it (only put 5% down). I could probably get over $250k for it now, so am considering selling it and moving to a small single family home. A $300k SFH would end up with about the same monthly payment if I put 20% down.
The houses I'm looking at have fairly small yards so I'm not too worried about the increased maintenance. I feel like the SFH would hold its value better than the townhouse, but I could be wrong there.
What would you do in my situation? Please let me know if I'm omitting any relevant info. Thanks! | First time home buyers, under contract for a 1930s Bungalow in Maryland with a failing septic tank.
Current sellers have lived in the house for 11 years and it seems although they pumped the septic system every 2 years, they weren't careful enough what they were allowing to get into it. They have a 10 year old son who I assume might be the part of the issue.
We had a septic inspection and it failed basically it needs a new leach field. There is a public sewage hook up across the street 170 feet away and the county is pushing them to hook up.
We got some estimates from the county on the seller's behalf and just to get the hook up across the street (State road) to in front of the house it'll be flat fee of $13,000 (250 Gallon Capital Connection Fee + Sewer Installation Permit) + in the ball park of $10,000 ~ $15,000 to dig up the road.
The sellers are also in contract to buy their new house so they have an incentive to work with us and had originally agreed to pay the cost to put in a new leach field for roughly $10,000. This was before we spoke to the county and determined where the public tap was and that they would force them into it.
I'm just wondering if anyone has had any experience dealing with the county and getting new sewer lines run? Are they argue with the county that connecting to public is too expensive and causing them hardship? Is there anyway to get discounts?
Also is there anything we can do as buyers to assist the sellers?
We pretty much had our agent forward everything to the sellers from contact information for the county, the permit guys, the 5 reputable plumbers and the estimated cost and said that they are follow up with everyone since we cannot move any further.
Outside of waiting for the seller to agree or deny hooking up to public sewage is there anything else we can do?
We have a 100% out if they decide not to which we're okay with but we want the house and want to work with the seller if possible and we're getting the house for a good deal, with great schools near our jobs and friends and family something we never thought we would find. | Council workers were forced to use a chainsaw to hack their way into a property after it had been left to become completely overgrown by its owner. The eyesore in Crewkerne, Somerset, had stood vacant since 2006 before it was seized by South Somerset District Council. The neglected South Street property was visited by council officials, police officers and a bailiff who required a chainsaw to cut back the thicket and weeds in order to gain access to the front door. Council workers had to use a chainsaw to hack their way into this property (pictured) in Crewkerne, Somerset, after it had been left to become completely overgrown by its owner . The property has been vacant since 2006 and has now been seized by South Somerset District Council . Once inside, officials were greeted with an empty home stripped of its valuables, with graffiti on the fire-charred walls, smashed windows and a burnt out sofa. After several attempts to contact the owner of the property - who the council say has failed to pay council tax for at least six years - the authority gained a court order to seize ownership. It is hoped that, once the costs are recovered through sale at an auction, the house will be renovated and made available for a local family to move in. A district council spokesman said: 'This property had been left to rot and had become an overgrown eyesore not far from the centre of Crewkerne. The council found the house was empty with graffiti on the walls, smashed windows and a burnt out sofa (pictured) After attempts to contact the owner of the property - who the council say has failed to pay council tax for at least six years - the authority gained a court order to seize ownership of the house . 'On Friday we took over control of the property after repeated attempts to try and enter into a dialogue with the owner about the future of the property failed. 'A locksmith secured the property and it will also now be guarded by a security company to prevent vandalism. 'Loans and grants can be offered in appropriate circumstances and the council always tries to negotiate a successful outcome with all parties concerned, but at the end of the day if all attempts fail it can resort to enforcement action.' Council workers had to hack their way through overgrown bushes and weeds to enter the property (left). Once inside they were confronted with graffiti and vandalism (right) Councillor Shane Pledger, portfolio holder for empty properties, said: 'We prefer to negotiate with owners of properties to get them back into use, but the case of this property in Crewkerne goes to show what can happen if owners leave properties empty and refuse to do anything about them. 'We will do all we can to ensure that properties in south Somerset are not left empty, let's not forget that a property brought back in to use is one less property we have to build. 'We have to ensure that we have enough housing for our residents and by bringing properties back into use, we can achieve that.' This Google Street View shows how the property looked back in 2008 when it was less overgrown . | My girlfriend & I recently moved in for the first time, a top floor flat, when we viewed the flat, we were told the lift was broken and we would need to call the building management company to find out when it will be repaired.
1 week into the tenancy and we called the building management company who told us the lift has been decommissioned as it would be to expensive to repair.
My question is, does this warrant some form of compensation, or drop in monthly rent? And how should I approach this? As when we were shown the flat, as far as we were concerned the building had a lift that was in the process of being repaired. It's also worth noting, my girlfriend has a minor disability which affects how far she can walk.
Thanks.
EDIT - We have just heard from the buildings management company the lift has been decommissioned since before 2016, and we were shown the flat last month. | Our homeowner's association is a major, major, major pain in the butt to deal with. They are very anal and strict about every single OCD thing you could imagine. They have sent me a few notice of violation that have been flat wrong and false. I recently lost my wits with them (because it was the 3rd completely false letter I received in as many months), and sent them (and the management corporation) a rather strongly worded e-mail. Today I received an e-mail from one of the members of the board pretty much warning me they could pursue legal action and put a levy on the property. I've read the rules and covenants and it appears this is correct: they could pursue me, for any reason and/or violation, and and should they prevail in the case, they get dibs on the property deed or levy a lien against it.
My questions are: what options do I have dealing with these peeps? Is there a way to dispute this power (which, IMO, seems excessive) they have to levy liens against my property? My pockets aren't deep enough to legally troll them, so that's out of the question. Is it a matter of put my cheek and take it? Any advice is much appreciated. | 1,999,745 | First time home owner. I bought a foreclosed house in Naperville about three years ago. This house had a dilapidated deck. So about two years ago I decided to replace it. I applied for the permit and about a month later it was rejected by the city owned utility.
It so happens that this deck sits around the electric meter. The original deck was built in 1992 with valid permit. Five years after the deck was built the public utility approved a policy that prohibits a deck to be installed over a service line and there was no grandfather clause.
Now that I want to replace the deck, the city owned utility wants me to move the electric meter at my own expense. When I purchased the house the inspector noted that the meter is surrounded by the deck but said it will be grandfathered in. I also had checked the city's deck permit application and there was no mention of this prohibition. It did not seem like the city had notified the previous residents that their deck was in violation of their updated policy, or put any note on the existing permit. I had my realtor check if the deck had a clear permit before my purchase and was told it was. Besides the neighboring city (my subdivision borders it), allows a deck in my situation as long as there is a removable access cover provided. Their electric utility however is ComEd.
While I agree that it is not prudent to have a deck built over a utility line, in my situation there is no where else that I can put this deck. I will be paying for the electrician to move the meter to the adjacent wall. However last week I got the estimate from the city to connect the meter to their service box which is 5m of straight line and it is well over $2000. All said, the total cost to move the meter would be over half the cost of the deck. To make matters worse I had pre-paid about 90% of the cost of the deck to a contractor whom I cannot locate anymore.
I am looking for advice if anyone has had been in a similar situation or any useful comments. I do not think it is fair that I bear the entire cost of moving the meter. | [CA] I live in a duplex and play utilities directly to pg&e, I just discovered my electrical panel only controls some of the circuits in my half of the house, is this legal? | Parents have just received a huge electricity bill but have had multiple appointments to change a faulty electric metre | Neighbours building extension problem.? | Estate agents not putting electricity in the meter as agreed in contract | Supplemental financing techniques: implications for electric utilities and the investing public | Can you relocate your house | Can I fence in an easement but still give access to power company? | The tampering of water consumption meters is a problem of increasing importance in many countries, resulting in economic losses for the water utilities. In the present article the great variety of tampering of meters are analyzed, defining the vulnerable points of them. Then it proceeds to analyze and compare the existing indicative and preventive measures to protect the meters, arriving at the conclusion that according to each 2020, Instituto Mexicano de Tecnología del Agua Open Access bajo la licencia CC BY-NC-SA 4.0 (https://creativecommons.org/licenses/by-nc-sa/4.0/) Tecnología y ciencias del agua, ISSN 2007-2422, 11(4), 244-278. legal situation there are measures that allow avoiding their tampering, vandalization and theft in an effective way. Finally, it is recommended for each legal situation what these measures are.Keywords: Tampering of water meters, water meter security devices, security seals.ResumenLa manipulación fraudulenta de medidores de agua potable es un problema de importancia creciente en muchos países, lo cual provoca pérdidas económicas para las entidades prestadoras. En el presente artículo se analizan las formas de manipulación de medidores, señalando sus puntos vulnerables. Luego se procede a analizar y comparar las medidas indicativas y preventivas existentes para proteger los medidores, llegando a la conclusión de que acorde con cada situación legal, hay medidas que de manera eficaz permiten evitar su manipulación, vandalización y robo. Por último, se recomienda para cada situación legal cuáles son las medidas a tomar.Palabras clave: manipulación de medidores de agua, dispositivos de seguridad de medidores de agua, sellos de seguridad.Open Access bajo la licencia CC BY-NC-SA 4.0 (https://creativecommons.org/licenses/by-nc-sa/4.0/) Tecnología y ciencias del agua, ISSN 2007-2422, 11(4), 244-278. |
1,999,746 | who built the skywalk in toronto | SkyWalk The SkyWalk is an approximately 500 metre enclosed walkway connecting Union Station to the CN Tower and the Rogers Centre (SkyDome) in Toronto, Ontario, Canada. Part of Toronto's PATH network, the SkyWalk passes above the York Street 'subway' and the Simcoe Street Tunnel and runs roughly parallel between Front Street and Bremner Boulevard. Designed by the IBI Group, the SkyWalk was opened in 1989 as a predominantly indoor connection from Union Station to the SkyDome. The primary purpose of the SkyWalk is to reduce the need for additional parking spaces near the stadium by providing a direct transportation link | A popular Russian blogger did a post on skyways/skywalks recently, ending with:
> This system only has one disadvantage: it kills the city completely. The ground floor dies off, and the upper floors do not become lively and attractive. You can find a doughnut shop or a Starbucks once in while, but altogether the system looks like a giant jet bridge. No life emerges in there.
Is it really that different? Are skywalk systems more common in colder areas? Is it really common or necessary to actually use the skywalk in such cities? | Carp, Ontario This former top-secret underground bunker was built to house key members of the government in the event of a nuclear attack on Ottawa. In 1960, NATO and the Canadian Department of National Defence built a satellite communications (SATCOM) station which supports a 68-foot diameter metal space frame radar dome (radome) on its roof, which provides environmental protection for the 50-foot diameter SATCOM antenna it houses. Until 1999 when NATO and DND decommissioned the site, the antenna provided satellite communications between all NATO countries. In 1999, it was purchased by Canadian Space Services Ltd. to serve as its corporate headquarters. The | are subjected to harsh environmental conditions. Canada's Walk of Fame Canada's Walk of Fame () in Toronto, Ontario, Canada, is a walk of fame that acknowledges the achievements and accomplishments of Canadians who have excelled in their respective fields. It is a series of maple leaf-like stars embedded in 13 designated blocks' worth of sidewalks in Toronto in front of Roy Thomson Hall, The Princess of Wales Theatre, and The Royal Alexandra Theatre on King Street as well as Simcoe Street. The first group of members was inducted in 1998, and to date 173 Canadians have been inducted into Canada's | are subjected to harsh environmental conditions. Canada's Walk of Fame Canada's Walk of Fame () in Toronto, Ontario, Canada, is a walk of fame that acknowledges the achievements and accomplishments of Canadians who have excelled in their respective fields. It is a series of maple leaf-like stars embedded in 13 designated blocks' worth of sidewalks in Toronto in front of Roy Thomson Hall, The Princess of Wales Theatre, and The Royal Alexandra Theatre on King Street as well as Simcoe Street. The first group of members was inducted in 1998, and to date 173 Canadians have been inducted into Canada's | I won't be able to make orientation since I can't arrive in Toronto at that time. Anybody have any ideas on what I should do? | Mike Filey had a column in the Toronto Sun for about 30 years and I read it for many years (I like learning about the history of Toronto) ... this book is a compilation of some of his columns.
We learn about Scadding Cabin, transit, Mother Parker's Tea Company, Hurricane Hazel, the Santa Claus Parade, Walt Disney's Canadian connection, the Toronto Postal Delivery Building (which would became the Air Canada Centre), Telemeter (pay-per-view back in 1960), the organ that was in Shea's Hippodrome and now in Casa Loma, and more.
Even though the book was published in 1994, it was still an interesting book because it dealt with many historical events in Toronto ... for example, the Air Canada Centre (ACC) was still in the discussion stages (it opened in 1999) when the book was published.
If you live in Toronto or are from Toronto, you should check it out. | 50 buildings or office towers are connected through the PATH system. It comprises twenty parking garages, five subway stations (Osgoode station connects only to the Four Seasons Centre), two major department stores, two major shopping centres, six major hotels, and a railway terminal. The CN Tower, Ripley's Aquarium of Canada, and Rogers Centre are connected via an enclosed elevated walkway, called the SkyWalk, from Union Station, although the walkway does not have indoor connections to these attractions. PATH (Toronto) PATH is a network of underground pedestrian tunnels, elevated walkways, and at-grade walkways connecting the office towers of Downtown Toronto, Ontario, | 1,999,746 | SkyWalk The SkyWalk is an approximately 500 metre enclosed walkway connecting Union Station to the CN Tower and the Rogers Centre (SkyDome) in Toronto, Ontario, Canada. Part of Toronto's PATH network, the SkyWalk passes above the York Street 'subway' and the Simcoe Street Tunnel and runs roughly parallel between Front Street and Bremner Boulevard. Designed by the IBI Group, the SkyWalk was opened in 1989 as a predominantly indoor connection from Union Station to the SkyDome. The primary purpose of the SkyWalk is to reduce the need for additional parking spaces near the stadium by providing a direct transportation link | when was the skywalk in toronto built | what is the name of the walking path that runs along king street in toronto | Want to Start Crossfit - Good Boxes in Toronto? West End/Vaughan | which line of the montreal metro has the terminus at henri-bour | what is the name of the train junction in toronto | when was the cn tower built in toronto | in which canadian city is the square one bus terminal | where does the metro link go from in halifax |
1,999,747 | Good toy but my dog was eating the material so ... | My dog was so excited to get a new toy but he chewed thru it the first night we had it. | This dog toy was adorable and my dog sure did love it! But it was so poorly made that she destroyed in in literally 10 minutes flat. | My hound/pointer mix chewed a hole and destuffed the poor thing in 15 minutes. I will say she did seem to be having a good time. She also had fun ripping the green fuzz off, that's when it went into the trash. The tag says they will replace the toy 1 time if destroyed so I'm going to give it one more go. | Good toy but my dog destroyed it (as she does most toys). This one lasted a bit longer than other toys I have purchased before it was chewed up. | good toy buy my puppy tore the stuffing out of the turkey pretty quickly. She still loves playing with it tho. Keep an eye on them | Great dog toy but it came new with a hole in it. Disappointed that I had to sew it up even before the dogs touched it. | Useless toy. My 7 month old beagle puppy tore it within an hour of play. | The toy was fine, but my dog was afraid of all the noise it made, so he doesnt use it. | 1,999,747 | Good toy but my dog was eating the material so I had to cut it off. Now he plays with naked ball and I do not have to worry about him eating it. I wish these ball would come without material | My dog is incredibly destructive and this ball is amazing!! She plays with it everyday | My dog loves this ball, brought it into the ... | Pretty much the only toy my dog has not chewed ... | My dog chews toys like they were made of paper | Beware this ball can be dangerous to your dog! | He has not removed those either so toy is pretty durable even for a serious chewing dog | If your dog tends to chew through toys, do ... | luckily its a super hard ball and they couldn't chew it apart but ... |
1,999,748 | Asking for early decision (Part time) | I have an interview scheduled at my second choice school (VCU) on 12/8/20, but they just emailed me and asked me if I wanted to move up to 10/7 or 10/8. The problem is, I don't know if I am sufficiently prepared. I've been preparing mostly for the two traditional interviews I have at the end of October, but VCU uses MMI. (I was planning to use all of November for MMI prep.) I'm not a natural interviewer,
I am someone who needs a lot of practice, though I find MMI scenarios easier than talking about myself. I haven't done any mock interviews yet, my first is actually scheduled for 10/7. I may be able to move that up to 10/5 or 10/6 if my boss is can find coverage. My family is willing to practice with me as well.
Should I take the earlier interview? Is the benefit of the interview being two months earlier worth the prep time I will lose? I really don't want to mess this up either way, by going in unprepared or waiting and not getting accepted. | I'm curious what your planning process is.
For me, I plan Monday through Thursday every weekend. By Friday, I usually fell behind enough through meetings/assemblies/misjudging assignment lengths to have enough leftover materials to use.
I'm currently ahead of that curve and thinking about planning even further ahead. However, I feel like if I start having materials ready for a month in advance, something big could change in my school (schedule change, new program, changing curriculum, etc.) making all of my materials wasted.
How far do you plan ahead? Would you plan ahead even further if you had the time? | Early decision Early decision or early acceptance is a common policy used in college admissions in the United States for admitting freshmen to undergraduate programs. It is used to indicate to the university or college that the candidate considers that institution to be his or her top choice. Candidates applying early decision typically submit their applications by the end of October of their senior year of high school and receive a decision in mid-December. In contrast, students applying "regular decision" typically must submit their applications by January 1 and receive their admissions decision by April 1. Some colleges offer either | Here's the process we have (we're a hyperlocal marketing company for small businesses):
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After a client pays, they're automatically redirected to complete an onboarding "quick start form" through Typeform
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After this "quick start form" is submitted, we want to automatically send a Google Calendar invite to that client the following business day at a specific time for our Onboarding Phone Call with our Fulfillment Team (say 3pm the next day) because right now we're manually doing it and it's causing issues.
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The Quick Start Form doesn't have any information related to scheduling the next phone call (there is a Zapier integration between Typeform and Google Calendar but it requires that the form have scheduling info) but we don't want to have that info since we want to be in control of the onboarding phone call scheduling.
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We use Zapier for our integrations (for example, between Stripe and TeamWork, or Typeform and Active Campaign).
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Is something like this possible???
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Thanks! | My girlfriend from Russia is studying in Dieburg since October but for some stupid reason her first student visa was only for three months, so it ends with December. She would have had an appointment today but because the public transport in her city was rerouted and out of schedule (which was not updated on their website) she missed it even though she headed off to arrive there half an hour early. Now she requested a new appointment but the first one they could give her is January 12.
What does this mean for her, having this *gap* in visa time? Does she have to leave the country? Will she have to pay a fine? How does this work? | I've gotten fee waivers and offers of early desicison from a couple of colleges, have any of you gotten this? Do you know why I'm getting these, because I have barely shown interest in the colleges that are sending them. | I need this class to graduate on time and emailed Tantalo before about it but wasn't helpful. If I don't get into this class I will definitely switch to part time student. But I want to do so before the quarter starts so I can get my full refund. What are my chances of getting off the waitlist? | Hi everyone!
I am starting a course next week with a professor who I would like to ask about research opportunities at some point. On the syllabus he talks about active participation in the course (its a credit/no credit seminar) earning you the right to ask about research. I would prefer to ask sooner rather than later for a few personal reasons, but I am wondering how soon is too soon? Is it okay to ask before the class is over? Would like 1 month be way to early? If you have any advice on how to gauge this kind of think, I would really appreciate it. | 1,999,748 | I applied to one part time program and already had my interview. Since then I received a job offer and negotiated tuition reimbursement into my potential comp plan.
I know I will need to let admissions know about this new job (if I accept), but would it be insane to ask for an early decision to make the choice easier for me?
I am sort of in limbo right now. The tuition reimbursement is a major factor in my decision but is obviously contingent on my acceptance this cycle... If I don't end up enrolling this cycle I would be more than happy to stay with my current employer to gain more experience in the industry (tech). | What happens if you apply early decision to two colleges? | Credit card tuition payment? | Can you licitly choose to pay the fixed monthly repayment on Student Loans (plan 1) when repaying from abroad? | One more summer(2022) left in school, but I don't feel ready to apply yet. Would delaying the application process to next Spring be the move, or just cram in the next few months for the Fall? | Asking for tuition reimbursement? | The pre-professional program at my University insists students go through them to apply to medical school. How much am I risking by deciding to go about it on my own without it? | College Admissions under Early Decision | Tuition Reimbursement HELP |
1,999,749 | Can niacin lower your cholestrol? | able to normalize vaginal pH and rebalance the vaginal microbiota, preventing and alleviating bacterial vaginosis. The consumption of probiotics may modestly help to control high blood pressure. Preliminary human and animal studies have demonstrated the efficacy of some strains of lactic acid bacteria (LAB) for reducing serum cholesterol levels, presumably by breaking down bile in the gut, thus inhibiting its reabsorption (where it enters the blood as cholesterol). A meta-analysis that included five double-blind trials examining the short-term (2–8 weeks) effects of a yogurt with probiotic strains on serum cholesterol levels found a minor change of 8.5 mg/dL (0.22 mmol/L) | That's not the best title, probably. I recently started taking citicholine and Bacopa again, and I feel... a hell of a lot better. I've taken these before and when I stopped, there was a "crash" but I didn't connect the two things at the time.
So I was wondering if anyone had heard of any syndromes or conditions related to low acetylcholine or low dietary choline intake? From what I've read, a dietary choline insufficiency results in NAFLD, there's not much about other symptoms. Physically I'm in decent health, just feel a lot better mentally with more acetylcholine. | We assessed the possible protective effects of N-acetylcysteine (NAC) against toxic damage in the rat colon. Two doses of NAC (20 mg/kg and 100 mg/kg) given for 2 days and 7 days after acetic acid administration (to induce colitis) were tested. NAC was dissolved in saline and administered locally (intracolonic), systemically (intraperitoneal) or in a combination (intracolonic and intraperitoneal). Several parameters, including macroscopic and histopathological scores and myeloperoxidase, glutathione and nitric oxide concentrations were measured using standard assay procedures. Treatment with 100 mg/kg NAC for 7 days significantly decreased tissue myeloperoxidase, glutathione and nitric oxide concentrations. The 20 mg/kg dose had no protective effects. The data indicate that NAC substantially reduced the degree of colonic injury, probably by regulating free radical production and inhibiting inflammation. It may, therefore, have a role in the treatment of inflammatory bowel disease. | What is the function of cholestrol'? | Niacin and Oxidative Stress: A Mini-Review | What affects the level of cholestrol in the blood? | Sodium nitroprusside administration to patients with acquired heart defects within early hours after heart surgery produced unidirectional hemodynamic changes, which however followed specific patterns, common to specific conditions. | I’m going to try out niacin for my mood and groundingness, should I be taking it everyday or will I develop some form of reliance, or vitamin proficiency, what are any potential bad side effects if any? And what’s the best quality/organic/cheap/bulk brand? | 1,999,749 | Is Niacin really safe for lowering Cholesterol? | The addition of niacin to statin therapy improves high-density lipoprotein cholesterol levels but not metrics of functionality | Niacin Inhibits Fat Accumulation and Oxidative Stress in Human Hepatocytes and Regresses Hepatic Steatosis in Experimental Rat Model | Influence of nifedipine on aortal cholesterol content, blood coagulation and elastin metabolism in cholesterol-fed rabbits. | Nilotinib attenuates endothelial dysfunction and liver damage in high-cholesterol-fed rabbits | are nitric oxide supplements safe? | nitroglycerin is less sensitive to | Potentiation of the cardiovascular effects of nitroglycerin by N- acetylcysteine | is mi relieved by nitroglycerin? |
1,999,750 | where did matt hardy lose his intestines | Matt Hardy Hardy was chokeslamed off the stage by Kane. Hardy then spent almost a year off from wrestling due to a severe knee injury. Along with his friend Rhyno, Hardy was released by WWE on April 11, 2005. Hardy's release was largely in part due to unprofessional conduct with social media after discovering Lita had a real-life affair with Edge. The public knowledge of the affair led to both receiving jeers from the crowds at WWE events, often resulting in chants of "You screwed Matt!", and, "We want Matt!". Edge and Lita used the affair and fan backlash to become a | Deos matt hardy hate jeff hardy? | Matt Hardy for the Cruiserweight Championship. After just barely making weight, Hardy defeated Billy Kidman at No Way Out to win the Cruiserweight title. At WrestleMania XIX, he successfully defended it against Rey Mysterio. Hardy lost the Cruiserweight Championship to Mysterio in the main event of the June 5 episode of "SmackDown" - the first and only time a Cruiserweight Championship match main evented a show. After dropping the Cruiserweight Championship, Hardy briefly feuded with Eddie Guerrero, but was unsuccessful in capturing Guerrero's United States Championship or Tag Team Championship. The Mattitude faction then expanded to include Crash Holly as Moore's "Moore-on" | Matt Hardy onward, he no longer considered Jeff as a partner or sibling. As part of the buildup to this feud, Hardy strongly implied that he was responsible for all of Jeff's accidents leading back to November, including an assault in a hotel stairwell that prevented Jeff from appearing at Survivor Series, an automobile accident where Jeff's car was run off the road, and a pyrotechnics malfunction where part of the pyro from Jeff's entrance was fired directly at Jeff, in an attempt to stop Jeff holding the WWE Championship. Despite Hardy's attempts to goad Jeff into fighting him, Jeff refused to | Jeff Hardy WWE Championship, his first world championship. In January 2009, Hardy's next storyline led to his involvement in scripted accidents, including a hit-and-run automobile accident and an accident involving his ring entrance pyrotechnics. At the 2009 Royal Rumble, Hardy lost his WWE Championship to Edge after Hardy's brother, Matt, interfered and turned on Hardy, hitting with a steel chair. The buildup to this feud involved Matt implying that he was responsible for all of Hardy's accidents over the past few months, and at WrestleMania XXV, Matt defeated Jeff in an Extreme Rules match and in a stretcher match on the April | Will matt hardy turn face? | Jeff Hardy Hardys continued to feud over the next few weeks, with the Hardys coming out victorious only once by disqualification. At Judgment Day, Lesnar gained the upper hand on the Hardy Boyz before tagging his partner, Paul Heyman, in to claim the win for the team. In July 2002, Hardy won his third Hardcore Championship by defeating Bradshaw. After years in the tag team division, Hardy took on The Undertaker in a ladder match for the WWE Undisputed Championship. Hardy came up short in the intense match, but earned The Undertaker's respect when he displayed courage by attempting to rise to | Is there any diseases for the large intestine? | 1,999,750 | Matt Hardy Regal, and the two acted as henchmen for General Manager Vickie Guerrero. At the June 22 taping of "WWE Superstars", Hardy suffered yet another injury, when his intestines went through his abdominal wall, during a triple threat match against MVP and Kofi Kingston. Hardy had suffered a tear in his abdominal muscle two years previously, but had not needed surgery until it worsened, and became a danger to his health. He was then traded to the SmackDown brand on June 29, and underwent surgery for the torn abdominal muscle on July 2. He made his return on the August 7 | who chokesled matt hardy off the stage | when did matt hardy lose the cruiserweight championship to myrio | who helped matt hardy at royal rumble | who replaced jeff hardy in the wwe championship | Will jeff hardy return the WWE? | who attacked jeff hardy after he lost the us championship | where did matt hardy assault jeff at survivor | who did matt hardy end up with at backlash 2009 |
1,999,751 | Ok binder in a category that doesn't have many choices. | My MOH got me this binder for planning. We picked a semi all inclusive venue. Making the binder somewhat useless. If I had to individually pick cakes, caterer, chairs, linens, dishes, DJ etc all with separate companies it would be WELL WORTH the money. But We really only needed to book photographer, videographer, DJ, invitations/favors and buy dresses & tuxes. Our venue is taking care of so much including cake, food, alcohol, linens, tables & chairs, florist that I have many blank pages of the binder. I am filling it out for a keepsake as we go but its not doing a ton of 'planning' organizing for me. | I really love the looks of this binder. I think however, that a 3ring binder would have been a better choice for me. To add extra pages can be quite a chore with the screws. | I'm trying to put together an awesome collection binder including things like my Ojama token set, ultimate and ghost rare signer dragons, every print of the Egyptian god cards, promos from the video games, every artwork of DM/BEWD, OCG art for censored cards, German ultis, millennium rarity prints, etc. I'd like to hear some more voices on what the coolest things I can put into my binder. So let's hear it! | This binder serves its purpose, I just wish it came with clear straps so that way it wouldn't fall down. | Original:
My mother will finally let me get a binder and we will order one in a few days since they’re going to a wedding in Slovakia .
I don’t but if you want here’s her ..... reasoning :
She believes that the binder will push my chest down (well duh) and this will damage the breast tissue. The damaged tissue will then become cancerous. So that’s what she says but I know differently. She just doesn’t want me to be different. Which yeah sucks and all but at least I’ll get a binder in the end. | To achieve the object, to provide a binder is available, which is an alternative to the processes known from the prior art binders for the preparation of sintered molded articles, a binder is proposed, comprising a first substance having a first melting point and a first vapor pressure at 80 ° C, a second substance having a second melting point and a second vapor pressure at 80 ° C, wherein the melting point of the first and second substance maxiaml is about 150 ° C and the vapor pressure of the first and second substance, at least about 5 Torr at 80 ° C. | My son absolutely loves this binder! It has made his middle school life smoother and easier to stay organized. I just ordered my other son the same binder because his brother loves his so much. Durable, lots of space and great organization capability. Plus he loves the strap to keep his hands free. | D-ring binders are the best and the ones with clear outside pockets (for labeling) are awesome too. Even if you don't use the outside view-pockets, they're nice to have in case you use the binder for something different later. | 1,999,751 | This size and shape binder are difficult to find so I took a chance with this one. It's okay but somewhat flimsy. Wish the main part was a stiff plastic rather than a thin bendy plastic. Other than that, it gets the job done. Wish there was more selection in this category though. | I’m considering a binder—do you have recommendations? | This binder is awesome! It is flexible so you can wrap the ... | This binder is really nice. It is only a tiny bit longer than ... | This binder is great. I was looking for a binder with a ... | What are some good binders? | My daughters love this binder | Binders are pricey, but if you want one that ... | Will a plus-size binder be made available? This one is too snug for me |
1,999,752 | Moonlight Ride tonight at Meadowbrook Park at 7! | Just wanted to know where everyone is staying! My friends and I are at the candlewood suites. Wanted to party with some people after the show! | I'm going uptown tonight and was wondering if anybody knows of a place that's open past midnight and is good? I know Pho 88 is open late but that place is so grimey... | For those two excited girls who said hi while driving (red suv) on I-20 near Weatherford :) | So does anyone know where the best places to park, I will be mostly liking coming to campus in at 8:30 AM.
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Thanks and have a great day! | was rather disappointed with the bonnaroo lineup this year and decided to switch it up. Couldn't find much until I stumbled across this lineup. WOW. I'm excited for the music. I'm excited to check out boston, I've never been. A few of my friends are disappointed the music ends a little early, but I am gonna be glad to get to bed a decent hour. No camping? No problem, now I won't smell and sweat in 100 degree heat all day. Got the airbnb booked. I'm sure there will be lots of others making the switch. What bars and areas do you guys recommend checking out outside of the festival? See you in a few months! | Hi all, I'm in the Phoenix area doing some hiking in the superstitions thru next Monday but looking for some stuff to do in the city as well. Anybody know any good shows happening nearby? | I'm out in Weston. For a good 45-60 minutes, it was the most intense lightening show I have EVER seen! My wife, daughter, and myself all sat our on the balcony watching it. It was like 4th of July, but with only white flashes... | I’m planning on checking out the South Beach skatepark this Sunday but I’ve never been, and I’m a newbie, so I don’t wanna get in anyone’s way. Hoping to go when it’s not busy. Anyone happen to know what times it’s usually pretty empty? | 1,999,752 | 75+ riders enjoyed the Moonlight Drive in May!
Bring yourself and friends and join the July Moonlight Bicycle Drive on Thursday July 2nd, departing from Meadowbrook Park in Urbana (Race Street WEST parking lot), and proceeding to Sidney Dairy Barn. The flavor of day is LEMON.
Gathering and socializing begins at 7:15pm with a prompt 7:30 departure. Expect at least two groups departing for the ride. Choose a casual ride speed or a quicker pace. No one is left behind. Some cyclists may proceed to Block or beyond before returning to C-U.
NOTE: A Metric #100km (62mile) option is now available. John Prince is leading this route Departure: 5pm from Meadowbrook Race St parking lot. Stops in Thomasboro, St Joe and Philo as well as Sidney. Planning to meet the 7:30 departure riders at the Dairy Barn at 8:15-8:30 Approximate 15-17 mph average speed.
If you have not experienced a moonlight ride, here's a 10-minute video with highlights from the 2013 May ride.
To get ready, please check out the LIB Bike Safety Quiz and enter for a chance to win $200 Encourage your friends and family who drive to take the motorist's version of the quiz. There is even a separate quiz for kids!
The National Bike Challenge is a nationwide event uniting thousands of current bicyclists logging miles for chances to win prizes Sign up now! The Challenge runs from May 1 to Sept. 30.
Cyclists are responsible for their own safety and navigation. And Illinois law requires the use of lights at night. Wearing helmets is a very good idea. Correct helmet fit is important for youir safety. Watch here:
EVERYONE IS INVITED. This is a community ride and not a sanctioned ride by any group or individual. Family, friends, co-workers, groups, individuals are invited. Please invite at least ONE of your friends!
| Visiting Cedar Point on July 31st, what are must rides? | Bike Route from Chinquapin area to Patterson Park? | Anyone ride in cincinnati? | which cycling event took place at ilkley moor in 2014 | 2018 Sept/Oct PA to NY Bicycle Tour | Can I ride now? [Minnesota] | How many of you are coming to Bikes Blues and BBQ? My advice as a native local. | Places to park and ride in Shadyside? |
1,999,753 | Does anyone in the triangle area know of a non-kill shelter for animals, or cats in general? | What kind of shelter does a cat need? | How much can you get a shelter cat for? | Cát Tiên National Park encroachment from local communities, illegal logging and poaching. In addition, the park is too small for the larger species found inside it. This has led to either their local extinction or conflict with local people as these animals move beyond the confines of the park. This problem is particularly intense for the park's elephant population, which is prone to wandering and is considered too small to be self sustainable. Since the early 1990s, partly as a result of the discovery of rhinos in the park, international donors and the Vietnamese government began to invest more money in protecting the park | And why do the shelters never seem to know why the pets were left there? Is there an anonymous drop off? And why would you take your pet to a shelter with a chance of it being destroyed when there are so many organizations that want to help rehome pets? | A rabid feral cat was found in Hilton. Keep your eyes out for any animals behaving strangely. Call the Monroe county health department for any further sightings or if you’ve been bit. | Overpopulation in domestic pets to neuter and rehabilitate them to prevent further attacks while also cooperating with the Bahrain stray dogs society group. The Canadian Federation of Humane Societies (CFHS) has been collecting statistics from Canadian animal shelters since 1993. A survey in 2013 included data from 100 of 186 humane societies and SPCAs. However, municipal animal services agencies were not included, hence "the data in this report represents only a fraction of homeless companion animals in Canada." In 2012, the surveyed shelters took in just over 188,000 animals, and euthanized 65,423 animals, representing 35% of all intakes. Six times as many cats were | It has been recently estimated by a reputable animal rescue group that there are in excess of 10,000 feral cats in my town. They have killed my pet chickens as well as several of my neighbors chickens (it is legal and not uncommon to have up to 4 chickens in your back yard in my town) They have killed at least 2 house cats in my neighborhood and a multitude of squirrels and possums, destroyed all of the bird's nests in my yard and killed all of the frogs and toads in the pond behind my house.
At this point I want to just take a gun and start capping them. trapping would have to be done on an industrial scale, but there is no shelter big enough to take thousands of cats. Animal rights groups are preventing the city from poisoning them. Basically, they are just being left to breed. I live in the south with mild winters, so nature will not help.
Any advice would be appreciated.
tl;dr - Feral cats have taken over my town. | I don't know where to ask for this kind of advice, so I though I could ask here. First of all, I live in a 3rd world country, different rules apply here. The reason I'm asking this is, I live close to the main street in my town, just next to the beach. There are always some cats and kittens hanging just outside my frontyard and most of them are very tamed. And sometimes, they just vanish without a trace and it hurts me, but I can't do much about it and I just hope that someone well-meaning took them to 'rescue' them. I'm feeding them daily, and If they have some immediate health problem, I take them to the vet.
So, am I doing something wrong? Does the fact that they are tamed and cuddly with random people on the street increase their chances of survival? Or am I doing them harm by practically domesticating them as outdoor cats and leaving them helpless in case some idiot wants to hurt them? Which is the lesser of two evils in this case? Thanks. | 1,999,753 | I am going to adopt out my three grown cats: ages 7, 4, 2. I need to find a new home for them, or a non-kill shelter soon. If anyone could help out with a name of a place that would be helpful. Thank you. | How to find a temporary home for our cats? | Looking for a home for a pregnant cat | Where can I put up a cat for adoption? | Looking for help re-homing/finding foster homes for cats (Ventura County/LA County, CA) | My parents want to adopt a cat or dog. Do you know of any that need a home? | Unable to care for cat. Looking for a new home. | Organization in Bangor, ME that helps stray/abandoned cats needs help to continue their mission | [FOR ADOPTION] Mama cat needs a home ASAP or to the shelter she goes. |
1,999,754 | when did bruck lesnar start his career in mma | Wes Brisco he should not have had to start at the bottom due to his Brisco family status. On March 10 at Lockdown, Brisco defeated Kurt Angle in a steel cage match, following interference from Aces & Eights Vice President D'Lo Brown. On the September 5 episode of "Impact Wrestling", Brisco and Garett Bischoff defeated the TNA World Tag Team Champions James Storm and Gunner in a non-title match. On the September 26th episode Magnus, Samoa Joe and Sting defeated Garrett Bischoff, Knux and Brisco in a six-man tag team match after Joe made Brisco tap out to the Coquina Clutch. After | Three of his most competitive matches have been against CM Punk, AJ Styles, and Daniel Bryan.
Yet other than like maybe a minute flurry, he’s basically squashed guys like Strowman, Reigns, Cena, etc. Randy Orton isn’t a huge guy but he’s much bigger than the aforementioned men and Lesnar killed him.
It seems that for the most part, Lesnar tries way harder when he’s wrestling small guys. Why? | Who is stronger brock lesnar or frank mir? | With his already push in WWE when he does appear, now add in a UFC win. Who in your opinion will/could cleanly pin Lesnar down the road? | Joe Lightfoot Joe Ventura (born 1953 in Montreal, Quebec) is a Canadian retired professional wrestler who was active throughout the 1970s and 80s. Although he is of Italian descent, Ventura had most of his success portraying an Indian (First Nation) under the ring name (Chief) Joe Lightfoot. He spent the majority of the 1970s competing in Canada for Stampede Wrestling and NWA All-Star Wrestling and the majority of the 1980s competing in the United States, primarily throughout the National Wrestling Alliance, where he is a former NWA World Junior Heavyweight Champion. Ventura began his professional wrestler career in the mid-1970s, | Brock Lesnar isn't that good of a champion. But John Cena is a tired and boring choice of new champion. I suggest that the title take a long run of maybe changing hands every PPV, with people like Dolph Ziggler and Barret taking shots with no long time champion so that WWE creative can sort out some of its other problems, like the boredom of the U.S. championship. | I'm talking about the Strowman/Lesnar thing.
How come people are okay with what Lesnar did? All I see in the comments is "lol Lesnar got him good" or "It was Braun's fault, he got what was coming for him"
Yeah, it was Braun's fault he hit Lesnar but it was accident but Brock was a bitch about it. He knows he can fuck someone up because he's an ex UFC fighter and still decides to do that shit on Braun. Fuck imo it even changed the match because Braun was moving very differently after that.
Brock didn't have a problem with giving a concussion to Randy at Summerslam even tho he "knew" how to make it look good. | My wife barely tolerates the sport but occasionally has the best commentary. She told me that "Brock Lesnar looks like he has a smaller man inside him operating him."
She has also stated that she was excited to watch the men "climb the ladder to fight over the suitcase". | 1,999,754 | Brock Lesnar won the IWGP Heavyweight Championship in his first match. After a contractual dispute with NJPW, he also wrestled as IWGP Heavyweight Champion in the Inoki Genome Federation (IGF). In 2006, Lesnar pursued a career in mixed martial arts (MMA), as he signed with Hero's and won his first fight, against Min-Soo Kim, in June 2007. He then signed with the Ultimate Fighting Championship (UFC) the following October. Lesnar lost in his UFC debut against Frank Mir and then won his second fight against Heath Herring. In November 2008, Lesnar defeated Randy Couture to become the UFC Heavyweight Champion. Shortly after | where does brock lesnar wrestle in wwe | Only 5 wrestlers in the WWE can beat Brock Lesnar's record | what year was brock lesnar born in | While I hate the fact Lesnar is a part time champion, I still love seeing Lesnar in action. Anyone stuck in this conundrum? | Brock Lesnar decided the last two WWE title changes | what is bruck lesnar's style of fighting | Will we ever see another even match with Brock Lesnar? | what title did batista win at smackdown 2006 |
1,999,755 | Flux entry fields in amorphous superconductors | For layered high-temperature superconductors we have calculated the current-voltage curve in the flux-flow regime when the magnetic field is parallel or slightly inclined to the plane of layers. We assume that there are no defects in the crystal and that the pinning is entirely intrinsic: It results from the interaction between vortices and the layered structure of the superconductor. | We have studied the current‐induced magnetic‐flux structures in type‐I superconducting constrictions using a high‐resolution magneto‐optical method. The samples were Pb films 60–100 μm thick with a single constriction of 0.5–1.0 mm width, similar to the Anderson‐Dayem bridge geometry. In the resistive state, moving flux‐tube trains are nucleated at both sample edges, at first precisely at the narrowest portion of the constriction. With increasing current, the flux‐tube trains extend more and more into the outlying regions performing a curved path. From the resistive voltage and our magneto‐optical observations the flux‐tube nucleation rate for a flux‐tube train is estimated using the Josephson relation. | A two-band model for the flux-flow resistivity and the Hall angle of type-II superconductors in low magnetic field regions is studied using the Bardeen–Stephen theory. The original theory considers free electrons only in the normal cores of the vortices. Results are obtained which qualitatively explain some experimental data. | Based on magneto-optical observations of flux distributions on high-T c single crystals and thin films aroundB=0 T at various temperatures, possible origins for the formation of the central peak commonly found in magnetization loops of hard type-II superconductors are discussed. The appearence of the central peak is closely related to the the full-penetration field,H *. It is shown that a reduction of the sample thickness influences the value ofH *, thus leading to a narrower field range for the rearrangement of the vortices when passingB=0 T. The role of pinning in the formation of the central peak and the role of the central peak in the formation of the fishtail effect is also discussed. |
I. INTRODUCTION
It is well known that in superconducting films a rather strong dc transport current in a perpendicular magnetic field B causes a motion of Abrikosov vortices thus leading to a nonzero, B-dependent resistivity. If vortex pinning is negligibly weak, the flux-flow resistivity is measurable even at small transport currents. In the flux-flow regime, the current-voltage curve (CVC) of a film is linear with
j = σ f E,(1)
where j is the current density, E is the longitudinal electric field strengh, σ f = σ f (B, T ) = σ n H c2 (T )/B is the temperature-dependent Bardeen-Stephen [1] fluxflow conductivity. Here σ n is the normal metal film conductivity and H c2 (T ) is the upper critical field. However, Larkin and Ovchinnikov (LO) showed theoretically [2,3] that the flux-flow regime at T close to the superconducting transition temperature T c becomes unstable at large current densities j j * which, still, are by far smaller than the depairing current density. It is this instability current density j * which sets the real upper limit for the current a superconductor can carry without dissipation.
In general, various mechanisms were suggested to explain voltage jumps in the CVCs of superconductors. To name a few, these are a thermal runaway effect due to Joule heating [4,5], formation of localized normal domains which appear in places of maximum current due to an inhomogeneous current distribution [6,7], crystallization of the vortex system [8,9], phase-slip centers or lines [10,11], and the Kunchur hot-electron instability [12,13] observed at T 0.5T c and related to thermal effects diminishing the superconducting order parameter, thus leading to an expansion of the vortex cores.
In the present work we will deal with the LO flux-flow instability at T T c relying upon the well-accepted LO instability scenario: The electric field arising due to the vortex motion accelerates quasiparticles within the vortex cores. This process continues as long as the quasiparticles energy becomes sufficient for their escape. If the time of the quasiparticle energy relaxation τ ε and the respective diffusion length in "dirty" films l ε = √ Dτ ε substantially exceeds the core size of the order of the coherence length ξ, then the excitations can leave the core. Here D = lv F /3, where l is the electron mean free path and v F is the Fermi velocity. The escape of the quasiparticles from the core under the influence of the electric field E causes the vortex core to shrink according to the LO relation
ξ 2 (v) = ξ 2 (0)/[1 + (v/v * ) 2 ],(2)
where v is the vortex velocity, ξ(0) = ξ(v = 0), and v * is the critical vortex velocity. The decrease of ξ leads to a reduction of the vortex viscosity η given by
η(v) = η(0)/[1 + (v/v * ) 2 ],(3)
and this is why the viscous force F v = η(v)v has a maximum at v = v * . A further increase of v > v * causes a reduction of F v . In turn, this leads to an even further increase of the vortex velocity and in this way results in the instability of the vortex motion. Experimentally, for current-driven measurements at not too large magnetic fields (B 0.4H c2 ) the nonlinear resistive part of the CVC usually exhibits a jump-like voltage rise (see, e.g. [14,15]). According to LO, these jumps emerge from the instability in the homogeneous flux-flow at the B-independent critical velocity
v * = 1.143(D/τ ε ) 1/2 (1 − T /T c ) 1/4 ,(4)
when the Lorentz force equals to the maximal viscous damping force F v .
The values of τ ε for In, Sn, and Al deduced from early experiments [14,15] by Eq. (4) agreed in the order of magnitude with the theoretical estimates. However, the authors of Ref. [15] revealed an anomalous dependence of τ ε on the applied magnetic field value. Another essential discrepancy between the LO theory and experiment [15] lies in a noticeable decrease of the instability current density j * with increasing magnetic field, whereas in the LO theory j * does not depend on B at small fields (B H c2 ). Later on, Bezuglyj and Shklovskij (BS) suggested [16] that the abovementioned discrepancies between the LO theory and experiments may have a common cause, namely the quasiparticles overheating not only inside the vortex cores, but also outside them. The latter ensues in experiments due to a finite rate of heat removal from the sample. Whereas LO supposed the temperature of phonons in the sample to be independent of the electric field value, BS argued that the phonon overheating is unavoidable since the rate of heat removal from the film always remains finite. In the BS generalization of the LO approach BS solved the linear heat balance equation
h(T 0 )(T * − T 0 ) = dσ(E * )(E * ) 2(5)
in conjunction with the CVC extremum condition
d dE [σ f (E)E] E=E * = 0.(6)
Here h(T 0 ) is the heat transfer coefficient from the quasiparticles at the critical temperature T * to the bath with the temperature T 0 , E * is the critical electric field, and d is the film thickness. Two regimes with respect to magnetic field values have been revealed, separated by the critical (overheating) field B T introduced by BS. Namely, when B B T quasiparticles overheating is negligible and v * is given by the LO formula (4). For B B T overheating becomes essential and the measured value of v * becomes B-dependent: At small fields it noticeably decreases with increasing field. An excellent agreement with the BS approach has been confirmed experimentally for both, low-temperature [17,18] and high-T c [4,19] superconducting thin films.
Nevertheless, both the LO and BS approaches to explain the nonlinear CVC behavior as caused by the fluxflow instability (FFI) capture no pinning in the physical picture. In reality, however, vortex pinning is omnipresent in superconducting films, and recent experiments on nanopatterned superconductors aimed at revealing its effect on the FFI critical parameters [20][21][22][23][24][25]. While a theoretical account for FFI at lower temperatures (T T c /2) has recently been given [26] and already allowed us to fit experimental data to the derived analytical expressions [25], the respective generalization of the BS approach at temperatures T T c has not been available so far.
To understand qualitatively the pinning effect on the FFI critical parameters, two limiting cases of weak and strong pinning should be considered. In the case of weak pinning, i.e. when the depinning current density j c is much less than the instability current density j * , the linear flux-flow regime is realized for j c j j * and the pinning effect on FFI should be negligibly small. In the opposite limiting case the absence of the CVC linearity just below the instability point may indicate that strong pinning is essential for determining the FFI parameters. The case of strong pinning is, in particular, interesting for the use of nanopatterned superconductors in fluxonic applications [27,28].
The objective of this paper is to provide a theoretical account for the pinning effect on the FFI critical parameters, namely the current density j * , the electric field E * , the resistivity ρ * , the power density P * , and the vortex velocity v * . The problem is considered within the framework of the LO model and its BS generalization at the substrate temperature T 0 close to T c of a nanostructured superconducting film. The treatment of the problem is at once based on the BS approach, because it contains the LO results in the natural limiting case B B T . The paper is organized as follows. In Sec. II A the phenomenological BS approach is extended to account for pinning effects on the flux-flow instability parameters. To model the pinning, the simplest form of a cosine washboard pinning potential is used. The rigorous results of Sec. II B are analyzed in the limit of weak pinning in Sec. II C and presented graphically in Sec. III in a broad range of magnetic field values and pinning strengths. A general discussion of the obtained results concludes our presentation in Sec. IV.
II. MAIN RESULTS
A. Formulation of the problem
For simplicity, a geometry is considered when the transport current is applied along the channels of a washboard pinning potential (WPP), see the upper inset in Fig. 1. In this case the nonlinear CVC of the sample can be presented as
σE = jν (j) ,(7)
where E is the longitudinal electric field and j is the transport current density. Here, ν = ν (j, T ) is a nonlinear function which can be considered as the (j, T )dependent effective mobility of the vortex under the action of the dimensionless driving Lorentz force j. Since 0 < ν < 1, this function can be treated as the probability of vortex hopping over the titled WPP barrier [29,30]. At T = 0, ν(j) is a steplike function with the condition ν(j) = 0 for j < j c , where j c is the depinning current density. For simplicity, only this regime for ν(j) will be considered in what follows. If j c = 0, then ν(j) = 1 and the linear CVC σE = j follows from Eq. (7) for the Bardeen-Stephen [1] conductivity σ. 27) of Ref. [30]. Upper inset: Experimental geometry. The transport current I is applied along the WPP channels (grooves). The vortex dynamics across the grooves leads to the appearance of the voltage V . Lower inset: Atomic force microscope image of a Nb film surface with a nanogroove array milled by focused ion beam [38] and inducing a pinning potential of the washboard type.
For nanostructured superconductors, where the vortex dynamics can be described as their motion in a cosine WPP [27][28][29][30][31][32][33][34][35][36][37][38], the nonlinear CVC of the sample can be presented as [30]
σE = j 2 − j 2 c or j = j 2 c + σ 2 E 2 ,(8)
where j c is the critical (depinning) current density indicated in Fig. 1.
Here
σ = σ f (1 − T /T c ) −1/2 [1 + (E/E * LO (T )) 2 ] −1 f (B/H c2 )(9)
obeys the LO expression for the nonlinear E-dependent flux-flow conductivity near T c in the dirty limit [3]. The function f (B/H c2 ) in Eq. (9), which takes into account the vortex core overlap, was tabulated in [3]. For magnetic field values of interest B ≤ 0.4H c2 (T ), it amounts to f (B/H c2 ) 4.04 [16]. With E * = v * (B/c), where the critical velocity v * is given by Eq. (4), for E * LO (T ) in Eq. (9) it was shown [2] that
[E * LO (T )] 2 = (B/c) 2 (D/τ ε )( 14ζ(3)/π)(1 − T /T c ) 1/2 .(10)H c2 (T ) = (4Φ 0 /π 2 D)k B (T c − T ),(11)
which is valid for superconductors with a short electron mean free path. Here Φ 0 = π c/e 0 is the magnetic flux quantum, e 0 is the electron charge, and k B is the Boltzman constant.
Following the BS approach we note that the quasiparticles temperature in Eq. (9) is independent of the electric field E. It should be found from the heat balance equation (5), which in the presence of pinning reads
h(T 0 )(T − T 0 ) = dE j 2 c + σ 2 E 2 .(12)
For the solution of Eq. (12) in conjunction with Eq. (6) we introduce, following Ref. [16], new dimensionless
variables e ≡ E * /E * LO (T 0 ) and t ≡ (T c − T * )/(T c − T 0 )
. In addition, we take into account that Eq. (9) can be identically transformed, using Eq. (11), to
σ(E, T, T0) = = 16.16σnck B (Tc − T ) πe0DB(1 − T0/Tc) 1/2 [ (Tc − T )/(Tc − T0) + E 2 /E 2 LO (T0)] .(13)
Now one can show that in the presence of pinning, the BS extremum condition given by Eq. (6) leads to the same result as in the absence of pinning (Eq. (29) in
[16]) 1 + e 2t dt de − e 2 √ t 1 − e t dt de = 0.(14)
Note that Eq. (14) derived in the presence of pinning does not depend on j c explicitly. From the heat balance equation (12) it is possible to derive dt/de and eliminate it from Eq. (14). To accomplish this, one first finds the derivative of Eq. (12) with respect to E and evaluates it at the critical point given by Eq. (6). The result is
dt/de = −(b/j 0 ) j 2 c + j * 2 0 .(15)
Here
b = B/B T , j * 0 = j 0 [2et/(e 2 + √ t)]
, and as in [16],
B T = 0.298hcτ ε e 0 k −1 B R , j 0 = 2.91(σ n /e 0 )(Dτ ε ) −1/2 (k B T c )(1 − T 0 /T c ) 3/4 .(16)
The parameter R = (σ n d) −1 is the sheet resistance. Next, in the dimensionless form Eq. (12) reads
1 − t = −(be/j 0 ) j 2 c + j * 2 0 .(17)
Then, from Eqs. (15) and (17) follows
dt/de = −(1 − t)/e.(18)
Finally, the elimination of dt/de from Eqs. (14) and (18) yields
e 2 = √ t(3t − 1)/2.(19)
It is worth noting that Eq. (19), which relates the variables e and t, coincides with Eq. (32) in [16], that is pinning has no influence on this relation.
Now, taking into account that j * 0 = j 0 [2et/(e 2 + √ t)]
, it is possible to derive from Eqs. (15), (18), and (19) an equation for the dependence
t = t(b, α), where α ≡ j c /j 0 , 2(1 − t) 2 b 2 √ t(3t − 1) = α 2 + 8t √ t(3t − 1) (3t + 1) 2 .(20)
For α = 0 (i.e. in the absence of pinning, when j c = 0) Eq. (20) has the solution t = t(b) obtained previously by BS [16]:
t = [1 + b + (b 2 + 8b + 4) 1/2 ]/3(1 + 2b).(21)
That is, quasiparticles overheating is b-dependent and it is given by Eq. (21). The equation for t(b) can be rewritten as
b(t) = (1 − t)(3t + 1)/2t(3t − 1).(22)
Since t > 0 per definition, 1/3 < t(b) < 1 follows from Eq. (22). From Eq. (22) it also follows that dt/db < 0 and t(b) monotonically decreases with t(b = 1) 2/3. The LO limit ensues at t → 1 and b → 0, while the BS limit corresponds to t → 1/3 and b → ∞.
B. Pinning effects on FFI parameters
Equation (20) is the key equation for the subsequent analysis. When α = 0, the solutions of Eq. (20) yield the dependences t(α, b) which will be used for the calculation of the FFI critical parameters in the presence of a cosine WPP. Namely, these are the critical electric field E * , the critical velocity v * , the critical current density j * , the critical power P * = E * j * , and the critical conductivity σ * (t) = j * /E * .
In the presence of pinning, Eq. (20) yields t = t(α, b) and t(α, b) → t(b) at α → 0. With the definition of t one obtains
T * (t) = T 0 + (1 − t)(T c − T 0 ),(23)
where T * (t) is a linearly decreasing function of t = t(α, b) for 1/3 < t < 1.
Proceeding to the electric field, we note that since e =
E * /E * LO (T 0 ), one has E * (t) = e(t)E * LO (T 0 ). Then using Eq. (10) one obtains E * LO (T 0 ) = bE 0 , where E 0 = 1.143(B T /c)(D/τ ε ) 1/2 (1 − T 0 /T c ) 1/4 ,(24)
and the physical meaning of E 0 was discussed in the BS work (see Eq. (34) in [16]). Finally, using Eq. (19), one derives
E * (t)/E 0 = be(t) = bt 1/4 √ 3t − 1/ √ 2.(25)
With the relation v * = (c/B)E * for the critical velocity and Eq. (25) one obtains that v * (t) in the presence of pinning is given by
v * (t) = e(t)v * LO .(26)
Here, v * LO is the LO critical velocity independent of E and B. It is given by Eq. (4) at T = T 0 . From Eq. (26) it is clear that the dependence of v * (t) on α and b is mediated by the dependence e(t) through Eq. (19).
We proceed now to an analysis of the dependence j * (t). From Eq. (9) taken at the critical point we obtain
j * (t) = j 2 c + (σ * E * ) 2 ,(27)
where, as follows from Eqs. (13), (19) and the definitions of e and t,
σ * E * = j 0 · 2et/(e 2 + √ t).(28)
Then, using Eq. (22), Eq. (27) can be transformed to
j * /j 0 = α 2 + 8t 3/2 (3t − 1)/(3t + 1) 2 ,(29)
Finally, comparing Eq. (29) and Eq. (20), where also j * 0 = j 0 · 2et/(e 2 + √ t) and j * 0 is equal to the right-hand side of Eq. (28), it follows that
j * /j 0 = (1 − t)/be.(30)
Now, having Eq. (25) for E * (t)/E 0 and Eq. (30) for j * (t)/j 0 it is clear that
P * (t)/P 0 = 1 − t,(31)
where
P 0 = E 0 j 0 = (h/α)(T c − T 0 ).(32)
In Eq. (31) P * = E * j * is the critical power density dissipated in the film, while P 0 is the power density corresponding to the temperature difference ∆T co = T c −T 0 > 0. Using Eqs. (25) and (30) it is possible to calculate the critical conductivity σ * (t) of the sample
σ * (t) = j * (t)/E * (t) = σ 0 (1 − t)/(be) 2 ,(33)
where σ0 ≡ j0/E0 = = (8.08/π) 2 (4, 1/π) 3/2 σnN (0)kB(kBTc) 1 − T0/Tc/hτε,
σ n = N (0)De 2 0 , and N (0) = mp F /π 2 3 is the density of states. A series of E * /E 0 versus j * /j 0 curves at the instability point is plotted in Fig. 2 for a series of values of the pinning strength parameter α = j c /j 0 .
C. Weak pinning
For convenience, we introduce the dimensionless pinning pinning strength parameter α ≡ j c /j 0 , the dimensionless magnetic field b ≡ B/B T , and denote Fig. 1 in [16]. Inset: Normalized power density P * /P0 versus normalized current density j * /j0 at the instability point for the same series of values of the pinning strength parameter α.
x(t) ≡ 2(1 − t) 2 b 2 √ t(3t − 1) , y(t) ≡ 8t 3/2 (3t − 1) (3t + 1) 2 .(
In the case of weak pinning (i.e. α → 0), Eq. (20) can be solved analytically using α → 0 as a small perturbation parameter. Thus, in the limiting case α 2 = 0 one obtains x(t 0 ) = y(t 0 ), where t 0 = t(b) was obtained in the BS work [16] and it is given by Eq. (21). Accordingly, for α 2 → 0 one can write t(b, α) t 0 − ε, where ε = A(b)α 2 1. Then it is possible to express the functions x(t) and y(t) at t = t 0 − ε in terms of x(t 0 ), y(t 0 ), and ε, namely
x(t 0 − ε) x(t 0 ) 1 + ε 2 1 − t 0 + 1 2t 0 + 3 3t 0 − 1 , y(t 0 − ε) y(t 0 ) 1 − ε 3 2t 0 + 3 3t 0 − 1 − 6 3t 0 + 1 .(36)
This leads to the following equation for A(b)
A(b) = t 0 (1 − t 0 )(9t 2 − 1) 2x 0 (3t 2 0 + 6t 0 − 1) ,(37)
which can be solved in the limiting cases of weak (b → 0) and strong (b 1) magnetic fields. Namely, when b → 0, one obtains t 0 (b → 0) 1 − b. Then, in the main approximation in b → 0, from Eq. (37) it follows that A(b → 0) b/2 and
t(b → 0) 1 − b(1 + α 2 /2).(38)
When b 1, from Eq. (20) one obtains t 0 (b 1) (1 + 2/b)/3. Equation (37) yields A(b 1) 2/ √ 3 and
t(b 1) (1 + 2/b)/3 − 2 √ 3α 2 .(39)
III. GRAPHICAL ANALYSIS
The objective of this section is to graphically analyze the dimensionless FFI critical parameters in the presence of pinning as functions of the dimensionless pinning strength parameter α ≡ j c /j 0 and the dimensionless magnetic field b ≡ B/B T , in a broad range of the respective parameters.
We begin our analysis with the critical electric field E * (t)/E 0 calculated by Eq. (25) and plotted in Fig. 3(a). We reveal that at any arbitrary value of α (0 < α < 2), E * (t)/E 0 is a monotonically increasing function of b. As the first check, we have proven that in the limit of no pinning at α = 0 the dependence E * (t)/E 0 coincides with the curve obtained by BS (Fig. 2 in [16]). The dependence E * (t)/E 0 is nonlinear, while with increasing α the nonlinearity is weakening as E * (t)/E 0 tends to become independent of b for b 2. In addition, one sees that whereas E * (t)/E 0 = 0 for all α at b = 0, at larger b values E * (α)/E 0 becomes a rapidly decreasing function of the pinning strength.
In contrast to E * (t)/E 0 in Fig. 3(a), which monotonically decreases with increasing α, the behavior of j * (t)/j 0 calculated by Eq. (29) as a function of α at b = const is opposite. Namely, j * (t)/j 0 strongly increases with α, see Fig. 3(b). We again check that at α = 0 the magnetic field dependence of j * (t)/j 0 coincides with the curve obtained by BS (see Fig. 3 in [16]), which is a monotonically decreasing function of b. At larger values of α 1 a part of the graph appears in Fig. 3(b), where the critical current density is independent of b. This part has a tendency to expand with a further increase of α. Figure 3(c) displays the critical power P * (t)/P 0 calculated by Eq. (31) as a function of α and b. The function P * /P 0 (α, b) is strongly increasing with b for 0 < b 2, exhibits a plateau at 2 b < 10 and large α, and it is only very weakly increasing as a function of α at a given value of b.
In Fig. 3(d) the critical temperature T * (t)/T 0 computed by Eq. (23) as a function of α and b at T 0 /T c = 0.8 is presented. While in the whole range of magnetic fields the relative changes in T * /T 0 do not exceed 16% for a fixed α and these changes primarily ensue at 0 < b 3, T * /T 0 is practically independent of α.
IV. DISCUSSION
Before a deeper discussion of the theoretical results obtained in this work in comparison with those presented in [2] and later in [16], we need to briefly recall the main theoretical FFI features at temperatures near T c in the absence of pinning obtained initially in those works [2,16]. According to LO [2,18], FFI for dirty films leads to the shrinkage of the vortex cores with increasing vortex velocity up to its critical value v * , refer to Eqs. (2) and (3). Then, for current-driven measurements the nonlinear resistive part of the CVC exhibits a jump-like voltage rise (23), respectively. The parameters BT and E0 are given by Eqs. (16) and (24). The thick black curves at α = 0 reproduce the BS results [16] without pinning.
at v = v * , when the Lorentz force equals to the greatest value of the viscous damping force for a vortex. In experiments [14,15], however, several discrepancies from the LO theoretical results were revealed, as already mentioned in the introduction. Later on, BS have shown [16] that these discrepancies may have a common cause, namely the overheating of phonons and quasiparticles in the film due to the dissipation during the vortex motion. The LO results were generalized by BS in a such way, that for B B T the overheating of the quasiparticles is small and the LO theory is valid, whereas for B B T the overheating of the quasiparticles is important and it allows one to explain the most of discrepancies from the LO theory discussed in [14,15,17]. It is essential that both, the LO and BS theoretical results were obtained without accounting for vortex pinning.
In the previous sections, within the framework of the BS approach, the influence of pinning on the FFI critical parameters for the current flow along the WPP channels at the substrate temperature T 0 close to the critical temperature T c of the nanostructured superconducting film (see Fig. 1) has been theoretically analyzed. While the FFI critical parameters in the BS paper [16] have already been calculated as b-dependent (b ≡ B/B T ), in this paper an additional α-dependence (α = j c /j 0 ) appears through Eq. (20), thereby introducing the variable pinning strength. The main tasks of the theoretical analysis was then to solve the main equation (20) with respect to t(α, b) and to reveal the influence of pinning on the FFI critical parameters, namely E * , j * , v * , σ * , and P * . As a natural passage to the limit α = 0, the solutions t(α, b) have been checked to coincide with the well-known BS results t(b). From the graphical analysis it is clear that, at a given magnetic field b = const, with increasing pinning strength E * decreases, j * increases, while P * and T * are practically constant.
We would like to stress that the introduction of pinning into the BS instability problem is phenomenological. Namely, instead of the linear CVC relation j = σ(T )E (at T = const) with σ(T ) = σ n H c2 (T )/B used in [16] here a nonlinear CVC at T = const generated by the cosine WPP and taken at T = 0 has been used. The conductivity σ(T ) in Eg. (8) is the same as that in Eq. (1). Being aware that the cosine WPP is a very particular form of the pinning potential, we emphasize that its advantage is a very simple CVC given by Eq. (8). Obviously, for an arbitrary pinning potential the CVC can not be described by a simple analytical expression.
Theoretically, it is also possible to use the CVC derived for the cosine WPP at T > 0 [30], but here the case T = 0 has been considered for simplicity. Further arguments in favor of the consideration of the CVC at T = 0 are related to the two main features which are crucial for the considered problem: (i) The CVC at T = 0 exhibits a nonlinear transition from the dissipation-free regime to the regime of viscous flux flow. (ii) The nonlinear transition at T = 0 allows for a straightforward determination of the depinning current density j c corresponding to the onset of the vortex motion. Such a simple determination of j c at T > 0 is impossible without introduction of further criteria. Obviously, the CVC at T = 0 is characterized by the parameter j c which, in turn, depends on the parameters of the WPP.
We now turn to suggestions for an experimental examination of the theoretical results obtained here. First of all, while a saw-tooth [29,[39][40][41] and a harmonic [30-35, 42, 43] potential are the most simple particular WPP forms widely used in theoretical modeling, they are found across numerous experimental systems. These systems range from naturally occurring pinning sites in high-T c superconductors [44][45][46][47] to artificially created linearly-extended pinning sites in superconductor thin films [27,28,[36][37][38][48][49][50][51][52][53][54][55][56][57][58][59][60], see e.g. Ref. [61] for a review. Systems with naturally occurring pinning sites are largely represented by cuprates in which one distinguishes the intrinsic pinning induced by the layered structure itself [44] and the planar pinning caused by uniaxial twins [45][46][47]. Artificial WPPs can be induced by a periodic thickness [48,49] or magnetization [50][51][52][53] modulation, thin film deposition onto facetted substrates [54,55], milling of periodically arranged nanogrooves in films by focused ion beam [27,28,36,38,56,57], and decoration of films with ferromagnetic nanostripes by focused electron beam induced deposition (FEBID) [58][59][60].
A further feature of the CVC given by Eq. (8) is that it is derived within the framework of a single-vortex model of anisotropic pinning [30]. For the most direct comparison of theory with experiment on, e.g. nanopatterned superconductors, this means that one has to tune the vortex dynamics in a coherent regime, when the entire vortex ensemble behaves as a vortex crystal. The background pinning due to undesired random disorder must be weak to ensure the long-range order correlations of the vortex lattice in the vicinity of the depinning transition. This can be realized e.g. in weak-pinning amorphous Mo 3 Ge [23], Nb 0.7 Ge 0.3 [13], and Al [21] films as well as in epitaxial thin films in the clean superconducting limit such as epitaxial Nb films on sapphire substrates [62].
The next experimental requirement is to perform measurements at so-called matching fields, when the Abrikosov vortex lattice is commensurate with the pinning landscape. That said, for a WPP each row of vortices shall be pinned at the position of linearly-extended pinning sites (for instance, nanogrooves shown in the lower inset to Fig. 1) and there will be neither vacant nanogrooves nor vortices pinned between them. It has been shown by computer simulations [40] that at the fundamental matching the vortex lattice has a crystalline structure, the effective vortex interaction is cancelled and the response of the vortex ensemble can be analyzed on the basis of that for a single vortex. The motion of vortices in this case is coherent, as can be seen, e.g. via ac/dc interference (Shapiro steps) in the CVCs [31,56,57]. These interference steps arise when the vortex hopping distance during one half ac cycle coincides with one or a multiple of the nanostructure period. Contrary, when B is tuned away from the matching condition, the vortex lattice becomes jammed and the vortex motion lacks coherence. This means that for a particular superconductor with a given periodicity of the WPP, one should perform measurements at a fixed matching field value instead of probing the whole range of magnetic fields 0 < B 0.4B c2 where FFI is observed [16]. At the same time, also the pinning strength parameter α is usually fixed for a given sample, with exception of cases [21,50,51] where the pinning strength can be tuned by a proper magnetic state of the individual element. In this way, to systematically compare theory with experiment in a broad range of magnetic fields and pinning intensities, a series of samples with different nanostructure periods and pinning strengths is required. The use of WPP landscapes with a tunable pinning strength appears as an alternative promising approach. This should be possible by decoration of films with ferromagnetic nanostripes using FEBID [58][59][60] in combination with post-growth processing [63,64] of samples for switching the magnetic state of the nanostripes and thereby changing the pinning strength.
The LO instability in superconducting films with a WPP has not been studied experimentally so far. For this reason, to examine our theoretical predictions, we would like to compare the main results of our phenomenological approach with an existing experiment [21] qualitatively. Silhanek et al [21] investigated the LO instability by measuring the CVCs of a 50 nm thick Al superconducting film deposited on top of an array of Py square rings. Their magnetic templates represent a flexible way to change the pinning strength by changing the magnetic state of the rings. Individual magnetic domains along each leg of the square rings were arranged to form either the so-called vortex state with a weak stray field or an onion state with a strong stray field. The experiment was carried out at T /T c = 0.89 in the magnetic field range 0 < B < B 1 B T ≈ 20 mT, where B 1 = 1.808 mT is the matching field corresponding to one vortex per unit cell. That said, the experiment [21] was carried out FIG. 4. Dependence of the normalized instability velocity v * /v0 (a) and the instability current density j * /j0 (b) on the dimensionless pinning strength parameter α ≡ jc/j0 and the dimensionless magnetic field b = B/BT calculated by Eqs. (25) and (29), respectively, in the low-field range. The parameters BT and E0 are given by Eqs. (16) and (24) while v0 ≡ cE0/BT . The thick black lines correspond to b = 0.1 for a comparison with the most closely related experiment of Silhanek et al [21], as detailed in the text.
in the low-field range, where overheating effects are not relevant. Importantly, at a fixed magnetic field value, the instability velocity v * has been revealed to decrease with increasing pinning strength, whereas the instability current density j * (slightly) decreased as the pinning strength increased, we refer to Fig. 5 in Ref. [21].
To augment their experimental observations, Silhanek et al [21] performed computer simulations relying upon the time-dependent Ginzburg-Landau equation. Their simulation results reported in Fig. 2 in Ref. [21] support both, the experimental observations of Ref. [21] and our theoretical predictions, as clearly seen in Fig. 4, where v * (α) and j * (α) are marked by thick black lines at b = 0.1 ≈ B/B T with B being in the vicinity of their matching field B 1 . In this way, even though the available experiment [21] was performed for a superconducting film with a different pinning potential, the main predictions of our phenomenological theory, namely a reduction of the instability velocity v * and an increase of the instability current density j * with increasing pinning strength qualitatively agree with the results of both, electrical resistance measurements and computer simulations [21]. A systematic comparison of the experimental dependences v * (α, b) and j * (α, b) measured near T c with Eqs. (16) and (24) should include a broader range of the parameters α and b.
Finally, the introduction of pinning into the FFI problem in the opposite limiting case T T c should be commented. At T T c FFI is caused not by the standard LO scenario assuming a vortex shrinkage due to quasiparticles escaping from the vortex cores, but rather by the Kunchur hot-electron mechanism [12]: At T T c , when the electron-electron scattering time is shorter than the electron-phonon scattering time, τ ee < τ eph , the distribution function remains thermal-like and the electronic system exhibits a temperature rise with respect to the lattice. In consequence of this, additional quasiparticles are created thus leading to a diminishing of the superconducting order parameter ∆. This results in an vortex expansion and a reduction of the viscous drag because of a softening of gradients of the vortex profile. All experimental observables were calculated in Ref. [12] as functions of the magnetic field value, by numerical integration of the heat balance equation. The experimental results for YBCO were successfully fitted to the predicted B-dependences and the j(E) curves in the absence of pinning without any adjustable parameters [12,65].
The effect of pinning on the hot-electron FFI parameters has recently been analyzed theoretically in Ref. [26]. There, as in this work, the pinning is introduced phenomenologically by using the nonlinear conductivity generated by the WPP instead of the Bardeen-Stephen fluxflow conductivity in the CVC. A simpler heat balance equation for electrons in low-T c superconducting films has been solved in Ref. [26] in the two-fluid approach, without numerical integration of the heat balance equation. A theoretical analysis has revealed [26] that the B-behavior of E * , j * and ρ * is monotonic, whereas the B-dependence of v * is quite different as dv * /dB may change its sign twice, as sometimes observed in experiments [20][21][22][66][67][68]. The generalized theory [26] of the hot-electron FFI has recently allowed us to fit a nonmonotonic magnetic-field dependence of the instability velocity in Nb thin films with different pinning strengths [25]. A systematic experimental study of pinning effects on the LO instability in Nb films with nanogrooves is currently under way and will be reported in a forthcoming publication.
V. CONCLUSION
To sum up, the effect of pinning on self-heating triggering the LO flux-flow instability in superconducting thin films has been investigated theoretically. The problem was considered on the basis of the Bezuglyj-Shklovskij generalization of the LO theory, with an account for a finite heat removal from the quasiparticles at temperature T * to the bath at temperature T 0 . The instability critical parameters, namely the current density j * , the electric field E * , the power density P * , and the vortex velocity v * have been calculated and graphically analyzed as functions of the magnetic field value and the pinning strength. With increasing pinning strength at a fixed magnetic field value E * has been found to decrease, j * to increase, while P * and T * remain practically constant. An account for vortex pinning has substantially supplemented the well-established FFI physical picture. Vortex pinning may be the cause for eventual discrepancies between experiments on superconductors with strong pinning and the LO results including their subsequent refinements. The theoretical predictions for a decrease of the instability critical velocity and an increase of the instability current qualitatively agree with the results of electrical resistance measurements and computer simulations [21]. For a quantitative comparison of theory with experiment a series of samples with different nanostructure periods and pinning strengths is required, to systematically investigate the flux-flow instability in a broad range of magnetic fields and pinning intensities.
FIG. 1 .
1Left axis: The nonlinear current-voltage curve (CVC) E(j) calculated for a cosine washboard pinning potential (WPP) of Ref. [30] in the limit of low temperatures. The dashed line corresponds to the free flux-flow regime E/ρ f = j, where ρ f is the flux-flow resistivity. Right axis: The respective nonlinear function ν(j) calculated by Eq. (
In Eq. (10) ζ(3) = 1.202 is the Riemann zeta function of 3. For the upper critical field near T c applies
35 )FIG. 2 .
352Normalized electric field E * /E0 versus normalized current density j * /j0 at the instability point for a series of values of the pinning strength parameter α ≡ jc/j0. For all curves, the blue spots outline values obtained at b ≡ B/BT = 10, while the red ones mark those at b = 0. The curve for α = 0 coincides with the BS curve in
FIG. 3 .
3Dependence of the normalized critical electric field E * (t)/E0 (a), critical current density j * (t)/j0 (b), critical power density P * (t)/P0 (c), and critical temperature T * (t)/T0 (d) on the dimensionless pinning strength parameter α ≡ jc/j0 and the dimensionless magnetic field b = B/BT calculated by Eqs.(25),(29),(31), and
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| We study theoretically the electronic and transport properties of a diffusive superconductor-normal metal-superconductor (SNS) junction in the presence of a perpendicular magnetic field. We show that the field dependence of the critical current crosses over from the well-known Fraunhofer pattern in wide junctions to a monotonic decay when the width of the normal wire is smaller than the magnetic length \(\xi_{\mathrm{H}}=\sqrt{\varPhi_{0}/H}\) , where H is the magnetic field and Φ 0 the flux quantum. We demonstrate that this behavior is intimately related to the appearance of a linear array of vortices in the middle of the normal wire, the properties of which are very similar to those in the mixed state of a type II superconductor. This novel vortex structure is also manifested in a strong modulation of the local density of states along the transversal dimension, which can be measured with existing experimental techniques. | Measurements of transport properties of amorphous insulating indium oxide thin films have been interpreted as evidence of the presence of superconducting islands on the insulating side of a disorder-tuned superconductor-insulator transition. Although the films are not granular, the behavior is similar to that observed in granular films. The results support theoretical models in which the destruction of superconductivity by disorder produces spatially inhomogenous pairing with a spectral gap. | This paper deals with a numerical method to study the electromagnetic behavior in a solid superconductor. The model shows that the anisotropy of hysteretic phenomena is influenced by the dependence of the critical current density on the induction field. | 1,999,755 | We have measured the flux entry fields (lower critical fieldsHc1) of homogeneous and inhomogeneous extreme type II amorphous superconductors based on zirconium. Samples are prepared by melt quenching at both ambient and elevated substrate temperatures. The degree of homogeneity is classified according to the widths of both inductive and resistive transitions. TheHc1 (T) curves for “powdered” homogeneous samples with weak flux pinning are found to be in good agreement with Maki's theory. Taking into account the electron-phonon renormalization effect, we deduce the zero-temperature energy gap values 2Δo/kBT c to be BCS like. On the other hand, anomalousHc1 (T) curves are observed in “powdered” inhomogeneous samples and strips from homogeneous samples parallel to the applied field. Appreciable irreversibility effects are also observed. The latter results are discussed qualitatively in terms of bulk and surface inhomogeneity effects. | We report the measurements of the temperature dependence of the resistivity, \rho(T), magnetic penetration depth,\lambda(T) the lower, Hc1(T), and upper, Hc2(T), critical magnetic fields, for single crystals of dodecaboride ZrB12, diboride ZrB2 and thin films of diboride MgB2. We observe a number of deviations from conventional behavior in these materials. Although ZrB12 behaves like a simple metal in the normal state, the resistive Debye temperature, 300 K, is three times smaller relative to that (800-1200 K) calculated from the specific heat, C(T), data. We observe predominantly quadratic temperature behavior of resistivity in ZrB12 below 25 K, and in ZrB2 below 100 K, indicating the possible importance of the electron-electron interaction in these borides. Superfluid density of ZrB12 displays unconventional temperature dependence with pronounced shoulder at T/Tc equal to 0.65. Contrary to conventional theories we found a linear temperature dependence of Hc2(T) for ZrB12 from Tc down to 0.35 K. We suggest that both \lambda(T) and Hc2(T) dependencies in ZrB12 can be explained by two band BCS model with different superconducting gap and Tc. | We have performed low-temperature specific-heat measurements in magnetic fields for a single crystal UBe 13 . It has been observed that our sample exhibits a superconducting transition at an intermediate temperature (T c ∼ 0.81 K) between previously reported values for two variant samples called H type and L type. The specific heat C(T ) of our sample shows a T 3 behavior below ∼ 0.7 T c , which is similar to the behavior of the H-type sample, suggesting the existence of point nodes in the superconducting gap function. We have obtained the upper-critical-field curves H c2 for the [001], [110], and [111] crystal axes, which show no anisotropy at least down to the lowest measured temperature of 0.5 K. We have also derived the Maki parameter κ 2 , and it has been revealed that the κ 2 steeply decreases isotropically upon cooling just below T c . Paramagnetic effects and the symmetry of Cooper pairing of UBe 13 are discussed. | High pressure resistivity measurements up to 8.5 GPa performed on the archetypal heavy fermion compound CeCu6 are reported down to temperatures of 30 mK. The pressure variation of the different characteristic temperatures and resistivity exponents are analyzed in the framework of recent theories aiming to understand quantum phase transitions. | Heavy fermions and unconventional superconductivity in high-quality single crystals of rare-earth and actinide compounds | The lower critical field, Bc1, is one of the fundamental quantities of a superconductor which directly manifests the Cooper pair bulk density in the material. Although this field can be measured using several techniques, the most conventional method is to calculate this field from the experimentally measured DC penetration field, Bp, which is defined as the starting point of the deviation of the DC magnetization curve, M(Bappl), from a linear dependence.Surprisingly, we found no mathematical routine which describes how this starting point of deviation can be found. Here, we propose the extraction of Bp from the fit of M(Bappl) dataset to the power law, where the threshold criterion Mc can be established by a convention. The advantage of this approach is that the procedure extracts one additional characteristic parameter: the power-law exponent. We demonstrated the applicability of this approach to polycrystalline ThIr3, WB4.2, BaTi2Bi2O, Th4H15, to thin films of Pb and MgB2 and to Nb single crystal. In most reports, Bc1(T) analysis is limited by the extraction of the London penetration depth. We advanced the analysis to extract primary thermodynamic superconducting parameters (i.e. the ground state superconducting energy gap, (0), the relative jump in electronic specific heat at transition temperature, ΔC , and the gap-totransition temperature ratio,2Δ(0)) from Bc1(T) data. This extraction was performed for Nb, ThIr3, TaRh2B2 and NbRh2B2. | We examine magnetic field dependent properties associated with the newly discovered field-induced superconducting state (FISC) in λ-BETS 2 FeCl 4 . These include the metal-to-antiferromagnetic insulator transition, the critical field of the FISC state in tilted magnetic fields, and the low-pressure, magnetic field dependence of the insulating and superconducting phases.Keywords: Organic-magnetic conductor, magnetic field induced superconductivityI.AFI transition, the anisotropic nature of the FISC state, and the anomalous behavior of the superconducting, AFI, and FISC states at very low pressures.II. Resistive transitionThe onset of the anti-ferromagnetic transition at 8 K is accompanied by a dramatic change in the resistivity of the material, which can increase by over 6 orders of magnitude. The nature of this transition is unique, since two mechanisms may cooperate to stabilize the AFI state, due to the π-d interaction. The columnar nature of the BETS molecular structure alone is susceptible to 1-D instability (i.e. a SDW transition), but the cooperative AF interaction of the Fe 3+ anions enhances this effect, making the transition essentially first order. The theoretical question arises[9] as to the Mott insulator vs. band (nesting) behavior of this transition. This behavior is shown inFig. 1afor one of four samples where the M-AFI transition was studied vs. magnetic field up to 8 T. In these measurements care was taken to insure that the connecting leads in the four-terminal measurements had an inter-connecting resistance of 50 G ohms. An electrometer with 200 T ohm input impedance was used to measure the voltage, and currents in the range 1 to 10 nA insured ohmic behavior over the entire temperature range. The logarithmic derivative (which gives the thermal activation energy E a vs. temperature) is shown inFig. 1b. Although there is considerable scatter in the data, it is generally observed (in all samples investigated to date) that the activation gap derived is of order 100 K at T AFI (B=0), but decreases to about 20 K for T = T AFI (B=0)/2.Fig. 1cshows the magnetic field dependence of T AFI and E a (at 4.5 K) over the range investigated. Of note is that the activation energy (e.g. for the zero field data), when compared with the standard BCS relationship 2E a /T c = 3.52, shows a significant deviation towards higher values, with 2E a /T c approaching 25 at T AFI (B=0). The theoretical prediction of Cepas et al. is that, if the AFI is a Mott insulator, E a should not vary significantly with field[9]. InFig. 1c, E a does not appear to decrease with increasing field, but rather, there is some indication for an increase in E a with field. Experimental uncertainties exclude any quantitative comparison at this time, and further work is needed to determine the field dependence of E a . | Temperature Dependence of the Flux Line Lattice Transition into Square Symmetry in Superconducting LuNi2B2C | Texturing of 3Y-TZP zirconia by electrophoretic deposition in a high magnetic field of 17.4 T |
1,999,756 | White ink tattoo touch up questions. | I don't understand the white ink tattoo logic. Why pay for something beautiful that is barely visible and will fade into nothing very quickly? If someone has the desire and commitment to pay for a tattoo, don't they want it to be visible for their whole lives? I have quite a few tattoos and they are something I look forward to seeing as I grow old. | What would ink pen ink do to you if you gave yourself a tattoo? | Can medical staff have visible tattoos? A survey study among students | The tattoos do not come off completely from the paperback, no matter how wet you get the tattoo. I think the glitter in the tattoos make the paper stick more to the tattoo. | What does a kiss tattoo on the wrist mean? | Marked (documentary) Marked is a television program produced by NorthSouth Productions for the History channel that premiered August 27, 2009. It explores the world of tattoos belonging to modern day tribes that operate at the edges of society, including motorcycle clubs, urban gangs, and hardcore prisoners. The show takes the viewer into the minds of members as they explain what the mysterious symbols decorating their bodies mean on the street, and mean to them personally. Initiation rites, turf wars, and the fierce pride of belonging to an outlaw family are all part of the territory. Tattoo artists and cultural experts | Of 779 third-year pupils from seven secondary schools examined for evidence of self-tattooing, 31 (4%) had tattooed themselves. More boys (27/513, or 5.2%) than girls (4/266, or 1.6%) had tattooed themselves. One hundred and fifty six separate marks were identified in the tattooed boys and sixteen in the girls. The most popular sites were the fingers and back of the left hand, and the front and back of the left forearm. Only 2 pupils remained pleased with their tattoos and 19 expressed strong remorse. Waiting lists for the removal of such tattoos are very long. The craze for self-tattooing by schoolchildren should be curbed. | Different types of tattoos and their meanings? | 1,999,756 | Hello everyone, recently I got a white ink tattoo on my wrist. The first two words came out perfect but the last word has a green/blue tint. It sort of looks as if the stencil stayed in my tattoo. From far away it looks like a small light bruise. I was wondering if someone had experience with touch ups with white ink tattoos. What are the results? Would a touch up even out the ink to a whiter color? | when was the tattoo on the cover of white light | White Ink Tattoo Artist Recommendations | Does it hurt having a tattoo on your wrist? | Wrist tattoo; Good or Bad idea? | Anyone have experience with tattoo allergies? | Healed tattoo ink raises up | Tattoo itching like crazy. Any good advice for relief? | Would it be weird to get a "test tattoo" with no ink to see how I heal? |
1,999,757 | New research shows that all "players" on other end are all actually computer AI, and that it's been internally programmed to give them the RNG advantage | Mastering StarCraft could drive forward the entire field of artificial intelligence (AI). On Wednesday, DeepMind and the game's creator, Blizzard Entertainment, opened a StarCraft training ground for AI--a suite of tools designed to make it easier for researchers to build them, and coming soon, hundreds of thousands of videos showing real games for them to train on. The new foray comes hot on the heels of DeepMind's success at cracking Go. Earlier this year, its AlphaGo, an AI with superhuman mastery of the game, defeated the world's best human player after analyzing and learning from millions of human games. | Are the AI characters boring to play against for you? Does playing against the computer help you get better at all? | A lot of people have gripes with the AI. This is why.
Traditional game theory AIs simulate each turn hundreds of times with each character randomly taking different actions. The game then chooses the actions most likely to produce a good outcome. This is great because it tries crazy strategies and all properties of a character and the opposing team have an effect. It also allows the AI to improve as the computer gets faster and can simulate more turns. Any decent chess game is written this way.
SWGOH doesn't do this. It has what we call an expert system. Each character has a specific set of rules, some of which are dumb because it's too much work to code specific smart rules for each character and to take all other characters into account.
So, there is no AI. There are a strict set of rules, and CG is lazy.
edit: Expert systems are a rudimentary form of AI, so the title is technically incorrect. My point is that the AI is not adaptive in any way. It's completely static, and doesn't adjust as the game changes unless CG specifically makes changes to it. | In 2014, AIIDE will host the Fifth Annual StarCraft AI Competition. Participants are given the task of building the best performing AI system for the popular real-time strategy game StarCraft Brood War (Blizzard Entertainment). The goals of the competition are to provide a testbed for real-time AI systems and to promote game AI research by ex- hibiting AI techniques such as scripting, planning, optimization, spatial reasoning, and opponent modeling in a fast-paced popular video game. | I guess the title pretty much explains it. Why don’t we have an option to play without the AI? To me it seems pretty simple because I have no experience in programming but, it must be a pretty challenging task. If anyone could tell me why they haven’t added this as a feature, I would appreciate it. (Also,sorry if this question feels a bit rude.) | In effort to achieve higher levels of realism in game play many companies are beginning to put more emphases on the creation of engaging, challenging opponents which is necessitating the use of several algorithms from the field of artificial intelligence. This paper will review these techniques, their implementation, and discuss who and how they are being used within the game development industry. | Here is my article about Artificial Intelligence in games. Sometimes i noticed that playing Pro evolution soccer or FIFA with my friends, the game gives one player more opportunities to win the game. It's never equal as in the games in the old days.
What do you think about AI in games ? | After 25 million games, the AI agents playing hide-and-seek with each other had mastered four basic game strategies. The researchers expected that part. | 1,999,757 | A common Hearthstone myth in the community is the assumption or preceieved situation where players feel like their RNG is always going well for the opponent and never well for themselves.
Common debunking theories are that this is the result of confirmation bias as well as the fact that if RNG is not going well for a player then it means that RNG is going well for the opponent on the other side.
HOWEVER, recent data-mining experts have discovered a shocking truth after analyzing Hearthstone server and data files along with information:
**ALL of the opponents that players face are never real human players.** Whenever a Hearthstone player ques up to play a ranked match against a supposed fellow human player, they are actually queing up against one of Blizzard's expertly programmed AI bots.
**The DIFFERENCE however is that internal workings have rigged it so that when RNG is meant to take place a complicated algorithm will set it so that based on current board status the computer will always get the best RNG results while the human player will always get the worst**
This ensures the situation where human players can always be cheated out of their wins through RNG and also ensure that no human player alive can ever experience the positive side of RNG.
Positive RNG in Hearthstone is all an illusion because the only "people" who benefit from it are the computer AI bots.
This startling new discorvery confirms the fact that the game is rigged against all human players and that they will never ever be lucky when faced against any opponent. We thank you for supporting this reserach and now you have the sufficient scientific proof to tell any myth debunkers that the myth is indeed inargubly true and that Hearthstone is out to get you. | When is RNG good? When is it bad? | Hearthstone would be terrible without RNG | What confirmation bias do you suffer from in Hearthstone? | The RNG in this game is bullshit | Why are MTG players so much more optimistic about new cards than Hearthstone players? | How do you counter this statement on the MMR system "One bad player can ruin an entire game and with bad luck you can run into equally bad or worse players consecutively and drop your MMR solely due to your teammates poor performance. I don't think it's a fair system." | Is Hearthstone really that impossible to come back to? | They need to make Arena less RNG |
1,999,758 | How to write more code? How to be a 10x + developer? | I want to improve my building skills, but I don't know how. So, would be great to have some tips to help me get better at it. I already tried watching tutorials on Internet, but don't seems to work :/
I think what's wrong is that I don't have the creativity to create and build awesome things on minecraft. Any tip specifically for this lack of creativity? | I'm currently a junior web developer and want to get really good at JavaScript. I know the fundamentals and can read it and understand it but not very good at writing it. What's the best way to improve, projects or coding challenges?
I'm not very good at being creative and coming up with new projects but sometimes think the challenges in codewars are a little random. Any help is greatly appreciated. | What kind of problems do experience while coding that drive you nuts 🥜 and what’s the tech responsible for it ? | I read that I should start with the basic functional version of my program and then build up, adding complexity as my software grows. I'm having trouble keeping everything straight in my head while writing < 300 line programs. What is the trick for keeping an idea clear in your mind no matter how many lines of code it takes?
[edit] I can express my ideas in python code but struggle when trying to translate them to English. | I was just wondering how you're using your coding abilities in your workplace, or what you're doing just for fun. | Fun and interesting exercises for the creative person in any of us. Go one exercise at a time and don't be afraid. You are your audience and there is no critic. These exercises allow you to open your mind and prepare you to write or paint or create the art that you want to create. I am a writer but I now find myself working with mixed media, something I never thought I would do until I read Bantocks books and purchased this book of tricks. | I'm currently self studying JavaScript (multi-dimensional arrays within indexes) on freecodecamp as I've finished with HTML/CSS course . However I limit myself of studying JavaScript only to like 1-2 hours a day to not over do it or overload my brain as it seems way harder in comparison.. and at the end of the day I want to remember the things I've studied.
This leads me to the question if it's okay for me to then do some html/CSS related problem solving for rest of the day to get better at those? If so.... I don't know where to begin.
I've seen some youtube videos recommending "leetcode" but erm that place looked very weird and it didn't have html from what I saw... just JavaScript from WebDev side from what I could see at a glance.
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Thank you very much in advance! | Hello! I made this short and sweet guide on some tips to become more of a productive coder, I touch a lot on any JetBrains IDE (IntelliJ, WebStorm, PhpStorm, etc..), Shortcut hotkeys that you can't live without, Terminal Tips you should know, Emmet, and Performance Optimizations.
I am planning to add some more soon, so let me know what you guys think! :)
Here it is:
| 1,999,758 | Basically I want to improve as a developer. I am smarter than most people I meet. But I have focusing issues that I have been figuring out.
But I realize that I am not a lot more effective than other developers. In that I write more lines of code, create more solutions. I want to be more effective in the work I do. Do more focused work for longer, do better work etc.
How do I do this? How do I become a 10x developer. I had a job for 1.3 years, and I realize that 'climbing the ladder' is not just programming skill. But I care about programming skill and want to approach the best in terms of skillset.
How do I do this? I don't mind putting in effort, giving up social life etc.
If you consider yourself near the top of the hierarchy in terms of skillset, how did you reach this level? What different ways of thinking helped you attain this goal? | How can I improve my programming skills? | Improve your Skills as a Programmer | How can I improve my skill as a front-end developer? | How can I become the best in everything I do? | WAYS ON GETTING MORE SKILL POINT - NEED HELP | Totally lost on what to do in Ultimate Talent Development Plan. Can someone give me some tips or a guide? (Explain like I'm 5) | How do I know what skills to build if I don't know what I am interested in? | What skills do you look for in a developer with a 20-year career? |
1,999,759 | when did the number of consignment stores start to decrease | on bad business judgment." The store, established on September 10, 1907, was lavishly furnished and stocked with clothing of a quality not commonly found in Texas. Within a few weeks, the store's initial inventory, mostly acquired on a buying trip to New York made by Carrie, was completely sold out. Oil-rich Texans, welcoming the opportunity to flaunt their wealth in more sophisticated fashion than was previously possible, flocked to the new store. In spite of the Panic of 1907 set off only a few weeks after its opening, Neiman Marcus was instantly successful, and its first several years of operation | suppliers denied access to the expected inventories. J. C. Penney J. C. Penney Company, Inc. (stylized as JCPenney) is an American department store chain with 864 locations in 49 U.S. states, and Puerto Rico. In addition to selling conventional merchandise, J. C. Penney stores often house several leased departments such as Sephora, Seattle's Best Coffee, salons, auto centers, optical centers, portrait studios, and jewelry repair. Most J. C. Penney stores are located in suburban shopping malls. Before 1966, most of its stores were located in downtown areas. As shopping malls became more popular during the later half of the 20th | Samuel Henry Kress walked 3 miles each way to the schoolhouse. In 1887, Kress opened a stationery and notions store in Nanticoke, Pennsylvania. As the business prospered he used his profits to open additional stores, naming his chain "S. H. Kress & Co." These eventually would become popularly known as the "Kress Five and Dime" stores. Unlike many businessmen of his day who only opened their stores in large urban areas, Kress wisely located his stores in smaller cities in 29 states he felt had growth potential. These stores became the jewel of many of these cities, which only had a dry goods | of retail shopping from "Marble Palace" that was called the "Ladies' Mile". By 1894, the major stores competed in the Christmas season with elaborate Christmas window displays; in 1895 Macy's featured 13 tableaux, including scenes from "Jack and the Beanstalk", "Gulliver's Travels" and other children's favorites. In 1877, John Wanamaker opened the United States' first modern department store in a former Pennsylvania Railroad freight terminal in Philadelphia. Wanamakers was the first department store to offer fixed prices marked on every article and also introduced electrical illumination (1878), the telephone (1879), and the use of pneumatic tubes to transport cash and | Vons for sufficient competition in markets where both Safeway and Albertson's stores had existed in price rivalry. One of the key buyers was Bellingham, Washington-based Haggen grocers which rebranded the newly purchased stores in Washington, Oregon, California, Arizona, and Nevada in early 2015 only to closed the affected stores just months later after Haggen was forced into bankruptcy as a result of purchasing the new stores. On April 18, 2005, Safeway began a $100 million brand re-positioning campaign labeled "Ingredients for life." This was done in an attempt to differentiate itself from its competitors, and to increase brand involvement. Steve Burd | By the late 1960s, the amount of 24-hour convenience stores increased to meet the needs of a younger population and people who were working late night or early morning shifts. Not surprisingly, the first 24-hour store opened in Las Vegas in 1963. Some convenience stores in the United States also sell gasoline. Only 2,500 stores had self-serve at the pump by 1969. 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1,999,760 | who owns the yadkin valley railroads | The Valley Railway was a shortline railroad which operated between the city of Cleveland and small town of Zoarville in the state of Ohio in the United States. The railroad was founded in 1871, but the first segment of track did not open until 1880 and the line was not completed until 1884. The Baltimore and Ohio Railroad (B&O) obtained a controlling interest in the Valley Railway in 1890. The railroad went bankrupt in 1895, at which time it was reorganized as The Cleveland Terminal and Valley Railroad Company (CT&V). The B&O took over operation of the CT&V in 1909, and the company was merged with the B&O in 1915.
Traffic on the road declined significantly after the 1920s. CSX, the B&O's successor, abandoned a third of the line in 1984. This portion was acquired by the National Park Service in 1987, and the Cuyahoga Valley Scenic Railroad operates on it seasonally. CSX sold about of track south of Canton to the Wheeling and Lake Erie Railway in 1992, and the track between Akron and Canton to Akron's METRO Regional Transit Authority in 2000. CSX continues some freight operations on the remaining track, which is referred to as the Cleveland, Terminal and Valley Subdivision.
The Valley Railway Historic District (a National Register of Historic Places site) encompasses the former Valley Railway from Independence to Akron. The railway also passes through or is adjacent to a number of other sites listed on the National Register.
Founding the company
The goal of the Valley Railway was to link the industrial centers of Cleveland and Akron, Ohio, with the coal fields of Stark and Tuscarawas counties.
The genesis of the railroad is somewhat unclear, however.
Possible antecedent efforts
Railway historians Sam Tamburro and Juliet Galonska have written that David L. King, a wealthy attorney in Akron, obtained a state charter for an "Akron and Canton Railway" in 1869. This charter was turned over to the Valley Railway in 1871. Ohio state historian Simeon D. Fess, however, mentions no charter for the Akron & Canton effort. Rather, he says Akron and Canton residents attempted to persuade the B&O to build a line between those two cities. They raised $300,000 ($ in dollars) in 1870 for the purchase of land and for construction. But when the railroad declined to build the line, the citizen-investors turned this money over to the Valley Railway in 1871.
Akron area historian Samuel A. Lane also discusses the fundraising attempt. He notes that King was a primary backer of the effort, but mentions no charter. Lane says the effort to build a railroad ended in the spring of 1871 for reasons which were unclear. The idea, however, gave rise to the Valley Railway. Canton railroad historian Craig Sanders also claims that area residents obtained a state charter for the Akron & Canton. However, Sanders says the line began construction 1873, and then ran out of funds. The route must have been different from the Valley Railway's route, as Sanders says both were being built in 1873.
Formation of the Valley Railway
Whether there were antecedent roads or not, the Valley Railway Company was incorporated in the state of Ohio on August 21, 1871. The incorporators consisted of Henry Chisholm, co-founder and primary investor in the Cleveland Rolling Mill (a steel mill); James Farmer, president of the Ohio National Bank; Samuel Augustus Fuller, founder of the Union Iron Works (a Cleveland iron foundry); David L. King; Nathan P. Payne, a Cleveland coal dealer; and Warrick B. Price, Midwestern real estate developer and former secretary and treasurer of the Milwaukee and Beloit Railroad and the Aetna Iron and Nail Company. The state-issued charter permitted the railroad to construct a line from the city of Cleveland on the shore of Lake Erie south-southeast to the village of Bowerston, Ohio.
The sale of Valley Railway stock began in January 1872. The intent was to sell $150,000 ($ in dollars) in stock in both Akron and Canton, and $500,000 ($ in dollars) in stock in Cleveland. King, the chief organizer of the corporation, raised $191,700 ($ in dollars) from Akron area investors. Sales fell far short in Cleveland, even after the Cleveland Rolling Mill bought $50,000 ($ in dollars) worth of stock.
The company was finally organized on April 24, 1872. Its directors were Farmer, King, and Payne, as well as George Cook (Akron-based director of agricultural implement manufacturer Aultman Miller & Co., and director of the First National Bank of Akron), James A. Saxton (Canton-based founder of the Stark County Bank), John Frederick Seiberling (Akron-based agricultural implement manufacturer), and Andros B. Stone (co-owner of the Cleveland Rolling Mill). The newly-constituted board on May 6 elected Farmer president, King vice president, and incorporator Warrick Price the secretary and treasurer.
Constructing the Valley Railway
The board of directors appointed P.H. Dudley, engineer for the city of Akron, as chief engineer of the Valley Railway. Because the intent of the railroad was to carry very heavy loads of coal to Akron and Cleveland, the board of directors mandated that the route follow a downhill grade between the two cities and that track curves be extremely wide and easy. The board contemplated building a narrow-gauge railway because it would be cheaper. Pressured by King, the board instead opted for the more expensive standard gauge in order to better link with other railroads.
Initial construction efforts
The route was surveyed and land purchased during 1872. On February 3, 1873, the railway contracted with Arthur L. Conger and Nicholas E. Vansickle (both of Akron) to build the railroad. Ground was broken in Springfield Township in Summit County in March 1873. The work initially proceeded very swiftly. By mid-August, two-thirds of the line had been graded (from Canton north almost to Cleveland), contracts for all the bridges had been let, and some bridges had even been partially completed. A financial panic hit in September 1873, creating worldwide economic havoc. The Panic of 1873 forced the railroad to indefinitely suspend construction on May 14, 1874.
By fall 1874, the railroad had run out of money and incurred debts of $150,000 ($ in dollars). To resolve the impasse and get construction going again, David L. King agreed to accept the position of president of the railway. He demanded, however, that the members of the board of directors personally assume financial responsibility for paying off the company's liabilities. The board agreed, and King was elected on September 25, 1874. To raise funds for construction, King traveled to Europe in February 1875, but failed to sell any bonds. Two years passed before King was able to interest bankers and investors in Cleveland and New York City to purchase the $6.5 million ($ in dollars) in bonds the railroad needed to complete work.
Walsh & Moynahan, new contractors, were hired, and work resumed on August 7, 1878. Once grading was complete, track began to be laid. The first rail was laid near Old Forge in Akron (near the present-day intersection of N. Arlington Street and North Street) on October 26, 1878. From Akron, rails were laid north toward Cleveland and south toward Canton; in Cleveland, the company began laying rails south to meet the line coming up from Akron.
Completing the line to Canton
Work was once again suspended on January 25, 1879, in a dispute over the quality of work provided by Walsh & Moynahan. A new contractor, the firm of Strong & Carey, was hired, and work resumed on June 3, 1879. When the Valley ran low on cash again, the Lake Shore and Michigan Southern Railway (LS&MS) loaned it about $250,000 ($ in dollars) to finish the track.
The line between Cleveland and Canton was completed on October 27, 1879. The first train (which carried important businessmen, civic leaders, clergy, industrialists, and politicians) ran on the line on January 28, 1880. Regular freight and passenger traffic began running on February 2, 1880.
Completing the line to Bowerston
Work on the remainder of the railroad slowed appreciably. The Valley Railway crossed the Pennsylvania Railroad's Fort Wayne Line in Canton, and followed the valleys of various streams and creeks to reach Mineral City, Ohio, which it did on July 15, 1882. There, it crossed the Pennsylvania Railroad's Tuscarawas Branch. It reached Valley Junction (Zoarville, Ohio) a few months later. Track work beyond Valley Junction was delayed because the Valley Railway had yet to negotiate trackage rights with the Wheeling and Lake Erie Railroad (W&LE). An agreement was finally reached in late 1882, and became effective January 1, 1883. The remainder of the line was completed swiftly, and in 1884 the Valley Railway between Bowerston and Valley Junction was completed—linking the Valley Railway with the W&LE and points east.
At the time of its completion, the Valley Railway had of main line track, of branch track, of siding, and a spur from Mineral City to a nearby Sieberling-owned coal mine. It linked northeast Ohio's three largest cities, creating a regional transportation corridor.
Valley Railway operational history
Depots
The Valley Railway originally built 16 depots. North to south, these were located at:
Cleveland.
Independence
Tinker's Creek
Brecksville
Boston Mills
Peninsula
Johnny Cake Lock on the Ohio and Erie Canal (later renamed Unionville, and still later Everett)
Hawkins (later renamed Ira; now no longer in existence)
Niles (later renamed Botzum)
Akron at Howard and Ridge Streets
Krumroy (south of Akron on Krumroy Road, between Marvo Drive and McChesney Road)
Myersville
Green
In 1884, Akron granted permission for the Valley to build a spur into the heart of the city. On this spur the railroad built a new, larger passenger depot at the intersection of Canal and West Market Streets in 1887. The railroad continued to use the old station at Howard and Ridge Streets until 1971.
Track bed lawsuit
A portion of the Valley Railway's route followed the bed of the abandoned Ohio and Erie Canal. The canal bed was originally owned by the state of Ohio. The railroad asked the Cleveland City Council if it would lease the canal bed to the company, and the council agreed to do so on March 24, 1879. On October 31, 1879, pursuant to previously enacted state law, Governor Richard M. Bishop transferred title to that portion of the canal within the city limits to the city of Cleveland. On November 4, 1879, the city formally leased the canal bed to the Valley Railway for 99 years. Although the value of the land was estimated to be $280,000 ($ in dollars), the city agreed to a one-time payment of $265,000 ($ in dollars), payable in Valley Railway corporate bonds. The railway filled the canal with ballast to create the track bed.
The state of Ohio was displeased that the city had leased the canal bed, and challenged the lease in 1879. A special joint committee was appointed by the Ohio Senate that year to examine the issue, but concluded that the city properly held title to the canal bed and could do with it as it wished. The joint committee's report was subsequently adopted by the Ohio Senate. This did not put an end to the dispute. In late 1895, Ohio Attorney General John K. Richards announced that, in his opinion, the lease to the railroad was illegal. The state then sued to recover the canal bed and evict the railroad. The state legislature adopted a resolution later that year in which it expressed its opinion that the transfer of title to the city had been proper under state law.
Discussions among the city, state, and Valley Railway continued until 1908. That year, an appraiser once more found in favor of the railway. Frustrated, the state attorney general filed a motion in state district court in early March 1908 demanding title to the canal bed. In October of that year, the railway filed a demurrer in the case. The case dragged on into 1910. The 1896 legislative resolution became an issue before the courts, with the state attorney general arguing that a resolution was inadequate to affirm the city's title to the canal bed. Only a bill could have confirmed title, the state argued in March 1910. The district court held for the state of Ohio. The railway appealed, and an appellate court held for the state of Ohio. The railway appealed to the Supreme Court of Ohio. In late January 1912, the Supreme Court of Ohio held in favor of the railway.
Baltimore and Ohio takeover
The Valley Railroad found itself in tight competition with the Connotton Valley Railway, which opened in January 1882 and had a similar route into the Tuscarawas County coal fields. Yet, coal was the key to the Valley's financial success: By 1888, 75 percent of the Valley Railway's income came from freight, and 40 percent of its freight tonnage was coal.
The Baltimore & Ohio Railroad (B&O) wanted to gain access to Cleveland, but lacked a route of its own into the city. In the spring of 1889, Taintor & Holt, a New York City investment firm, began buying up the Valley Railroad's stock on behalf of the B&O. The firm turned this stock over to the B&O in the fall of 1889. With the assistance of Valley board member Sylvester T. Everett and Valley president Jeptha Wade, the B&O obtained majority ownership of the Valley Railroad in late 1889. At the board of directors meeting on January 8, 1890, the B&O installed three of its own candidates on the Valley's board of directors. Wade resigned as president, and the new board elected Thomas M. King (a B&O official from Baltimore) president in his place. Sylvester Everett was elected the railroad's new vice president.
1895 bankruptcy
The Valley Railway was financially successful. In its first decade, the railroad's main cargoes were coal, copper ore, iron ore, lime, sand, and stone, but it carried much less agricultural produce than had been estimated. By 1892, four trains a day ran the entire length of the railroad, with two additional trains running each day between Cleveland and Akron.
Worldwide financial difficulties led to the Valley Railway's collapse in 1892. They began with the Baring crisis in the United Kingdom, a banking panic which spread to the United States and caused a major recession in 1891. The Valley Railway went into receivership in 1892. The railroad might have recovered, but the Panic of 1893 led to another significant downturn in both passengers and freight traffic. The railroad tried to build revenue by constructing a branch from the main line at Willow (Old Brecksville Road) along Mill Creek to E. 76th Street, and then E. 76th Street and Jones Road to Broadway Avenue. This track was intended to serve the old Newburgh area's steel industry, and became known as the Newburgh Branch.
Expansion proved unsuccessful. The Valley Railway had been the primary means of travel from Canton to Akron to Cleveland, but in 1895 the Northern Ohio Interurban Railroad opened. This inexpensive light rail service effectively destroyed the Valley Railway's passenger traffic between Cleveland and Akron, eliminating a major source of the company's revenue. The Valley defaulted on its bills and interest payments and went into full bankruptcy on August 2, 1895.
The company was reorganized as the Cleveland Terminal and Valley Railroad (CT&V) on October 3, 1895. As part of the reorganization, the Valley transferred property worth about $250,000 ($ in dollars) to the LS&MS as payment for the 1879 loan.
Cleveland, Terminal and Valley Railway
New Cleveland passenger and freight facilities
In February 1896, the CT&V announced it would construct new, larger freight and passenger facilities in Cleveland to accommodate the increased business it was doing in the city. The existing passenger depot at the foot of Seneca Street (now W. 3rd Street) would be demolished and a long, deep, two-story station built on the same spot. A long train shed, parallel to the rear of the depot, would also be built. A trestle would bring the trains up to the level of the station and train shed. The CT&V also acquired of riverfront along Columbus Road, south of Center Street. The company said it would build a second freight station and extensive new docks there, complete with McMyler rotary car dumpers. To connect the new freight station and docks with the main tracks, the railway asked the city to close Lime Street. The total cost of the project was estimated at $500,000 ($ in dollars). The freight station, which also featured derricks to assist with the loading of heavy cargo, was completed in June 1896 and the old freight depot retained as a storage facility. The steel-frame station was deep and long, with walls and roofing of sheet metal. There were 25 loading bays on the dock side alone, and traveling overhead cranes facilitated the movement of heavy loads onto pallets or into freight wagons.
As part of the freight expansion, the CT&V built a second freight depot and docks on the Cuyahoga River between Main Avenue and Cathan Avenue (just west of the Superior Avenue Viaduct Bridge). The city of Cleveland, however, wished to widen the Cuyahoga River by at this point. The city and the railway came to an agreement whereby the city would close West River Street and give this of land to the railroad. The of land on which the CT&V docks sat would be removed to allow for the widened river channel. Since the river was a "highway" under state law, the railway agreed to pay an assessment of about $16,500 ($ in dollars) for "highway improvements"; in return, the city agreed to rebuild the CT&V's docks.
The new passenger depot began construction in September 1897. Designed by local structural engineer A. Lincoln Hyde and architect William Stillman Dutton in a modified Gothic Revival style, it was built by contractor C.N. Griffin. The structure was much different than originally projected, just long and deep but with three stories rather than two. The roof was of slate, mined in Virginia. The building's steel frame had a first floor facade of rock-faced blue sandstone, while the upper floors were of buff pressed brick trimmed with stone. Turrets at the corners helped to strengthen the building, and clock tower illuminated by floodlights rose from the steeply pitched roof. The clock mechanism was designed and built by the local firm of Scribner and Loehr. The baggage room on the lower level had an asphalt floor. At the main entrance on the first floor was a vestibule from which passengers could pass into the lobby. Men's and women's waiting rooms were located on either side of the lobby. First story flooring consisted of mosaic tile manufactured and installed by the Newcastle Block Pavement Co. of Pittsburgh. The walls were painted a reddish-orange and featured wood wainscoting painted dark green, with oak trim and moldings on the walls and ceiling. An elevator and stairs led from the vestibule to the upper floors. The second floor housed the CT&V's corporate headquarters, and featured mosaic tile flooring and walls painted ecru with oak trim. A large brick pillar, running through the building to the foundation, supported the heavy safes in the auditor's and engineer's offices. The third floor contained the railway's engineering and telegraphy offices, while the attic was used for records storage. The entire interior was electrically lit. The train shed was just and wide. The cost of the new passenger station was estimated at $100,000 ($ in dollars). The train shed behind the new station was only the second of its kind erected in the United States. Constructed by the Massillon Bridge Company, it consisted of two levels—one for the receiving of incoming and outgoing passenger traffic, and the other for the making up of trains and the loading of special trains.
Route changes, trackage right leases, and new spurs
With the depression caused by the Panic of 1896 ending, the CT&V did very well financially. It gave the Wheeling & Lake Erie trackage rights over the entire length of the CT&V, built a new freight depot in Cleveland on Seneca Street near the Central Viaduct (a block north of what is now W. 3rd Street and Harrison Street), and purchased between end of its tracks and Lake Erie for use as a rail yard. This land was obtained from the city of Cleveland for $6,000 ($ in dollars). The CT&V subsequently built up the land so it would no longer flood.
On November 9, 1898, the Sandyville and Waynesburg Railroad was chartered to build a line between the C&TV line at Sandyville northeast about to Waynesburg, Ohio. The line was completed on July 1, 1899, and leased to the CT&V. (The line was originally intended to be long.)
In April 1899, the Davis Railway Co. constructed a extension of the spur at Mineral City. This branch pushed east along Huff Run to Linden (an unincorporated crossroads hamlet) and the Davis Mine No. 2 coal mine. The entire length of the spur from Valley Junction to the mine became known as the Huff Run Branch. Mining was so important in the area that the Huff Run Branch later added of second track and of sidings.
The B&O was threatened with losing access to many of the southern Ohio markets it relied on in 1899. The first threat came from the Cleveland and Marietta Railway. In 1872, it built a branch line from Marietta, Ohio, to the B&O main line at Harmer Junction. This allowed B&O and CT&V freight to be shipped on the Cleveland and Marietta (C&M) directly to Cleveland (or to be transferred at Canton and shipped to Cleveland). The Cleveland and Marietta said it would no longer accept freight for either railroad beginning January 1, 1900. That same year, the Wheeling & Lake Erie acquired the Cleveland, Canton and Southern Railroad, whose track from Cleveland to Canton and then to Coshocton and Zanesville. The W&LE said it would cancel the CT&V's trackage rights, which threatened to cut the CT&V completely off from all southern routes and markets. In response, the CT&V began to swiftly survey a route from Valley Junction to Canal Dover (now Dover) and then to Newark, Ohio, which would give it a link to the B&O's main line and threaten to eat significantly into traffic on both the C&M and the W&LE. To avoid construction of an independently owned new main line, the Pennsylvania Railroad agreed to give the B&O subsidiary trackage rights between Valley Junction and Canal Dover. At Canal Dover, the CT&V connected with the Lake Shore and Tuscarawas Valley Railroad (now operating as the Cleveland, Lorain and Wheeling Railroad).
The CT&V thrived financially, and so did business along its route—and the railway expanded to meet this demand. In 1900, the Cleveland-Boston Bag Co. built a large mill near the tiny hamlet of Boston Mills to take advantage of the railroad. Boston Mills soon grew into a town. In 1904, the railroad built a spur from Willow (the modern intersection of Fuhrmeyer Road and Old Brecksville Road) along Mill Creek to connect with the Cleveland Short Line Railway near what is now E. 73rd Street and Deveny Avenue in Cleveland. That same year, the railway spent $115,000 ($ in dollars) strengthening all the bridges along its route, and even rebuilding some older ones, so that it could haul heavier loads and use new, heavier, more powerful locomotives. In 1905, the Jaite Paper Mill opened north of Boston Mills to take advantage of open land near the railroad as well.
New B&O rail yard
In 1906, the B&O closed the existing CT&V roundhouse and built a $400,000 ($ in dollars), much larger roundhouse and rail yard on W. 3rd Street in Cleveland. The 10-stall semicircular roundhouse measured on the outside and on the inside and cost $45,347 ($ in dollars). Another $200,000 ($ in dollars) was spent building the rail yard.
Other improvements included:
A $12,500 ($ in dollars), , deep cinder pit located about south of the new roundhouse;
A $26,370 ($ in dollars), sand house and coal tipple located south of the new cinder pit;
A two-story brick resthouse for trainmen northwest of the roundhouse, with second-floor reading and sleeping rooms;
A one-story machine, blacksmith, and engine and boiler repair shop made of brick attached to the north end of the roundhouse;
An $11,000 ($ in dollars), storehouse and oilhouse north of the roundhouse; and
$145,000 ($ in dollars) in infrastructure improvements, which included a steam heating plant, smokestack, fresh water system, drain and sewer system, blow-off lines, and two water tanks.
Bridge replacements in Cleveland
A controversy broke out in 1905 over whether the CT&V would be required to replace its railroad bridge over the Cuyahoga River. At issue was a swing bridge over the Old Ship Channel of the Cuyahoga River. The Constitution of the United States and various federal court rulings gave the federal government control over all navigable waters, and the United States Army Corps of Engineers (tasked under federal law with improving navigable waters) asserted the right to regulate the bridge. The Corps wanted the bridge removed or replaced, since the center pier of the bridge hindered traffic in the Old Ship Channel and the embankment spans, when open, used up space which the Corps wished to use for new docks. The CT&V, however, argued that the 1825 changes to the river rendered the Old Ship Channel and the New Ship Channel man-made waterways and hence not subject to federal jurisdiction. Local hearings were held which documented the hindrance to water traffic, and the railroad agreed in April 1905 to remove the swing bridge no later than April 1, 1907. Secretary of War William Howard Taft then intervened, ordering the bridge gone by April 1, 1906. Although the railroad objected to the tight timeframe, it went ahead with plans for the new bridge as ordered. The railroad proposed a replacing the existing structure with a Scherzer rolling lift bridge, a plan which was approved in August 1905. The new bridge opened in September 1906. Designed by the Scherzer Rolling Lift Bridge Co., manufactured by the King Bridge Co., and erected by the Pittsburgh Construction Co., the double-track, bridge cost $180,000 ($ in dollars).
The B&O, of its own accord, then rebuilt two more bridges in Cleveland. The first was over the Cuyahoga River near what is now Quigley Road and W. 3rd Street. The rolling lift bridge was built by the King Bridge Co. and completed in July. Planning for replacement of a second bridge, this one spanning the Cuyahoga at what is now Carter Road (on the west bank) and W. 3rd Street (on the east bank), began in June 1908. Originally, this rolling lift bridge was to be long and cost $200,000 ($ in dollars). Construction of the bridge was delayed, however, when the city of Cleveland began planning for a new viaduct over the Cuyahoga River valley near the same location. By November 1908, the city had decided to widen the river at this location, and asked the railroad to construct a longer bridge. Discussions between the city and railroad ensued, and it was not until August 1909 that both sides agreed to a $275,000 ($ in dollars), long rolling lift bridge. Built by the Pennsylvania Steel Co., construction took nearly 18 months. Taking into account its piers, abutments, and approaches, it was the largest rolling lift bridge in the world.
The company also repaired a swing bridge just downstream from what is now the Center Street Bridge. This swing bridge was severely damaged when floods sent three ships crashing against the bridge. The CT&V sued for damages, and the case went to the United States Supreme Court. The Supreme Court held in Cleveland Terminal and Valley R. Co. v. Cleveland S. S. Co., 208 U.S. 316 (1908), that bridge piers, bridge protective pilings, and docks were not "aids to navigation" and thus damage to them by a ship (even if on navigable waters) was not a cause for action under United States maritime law.
B&O takeover
In June 1909, the B&O assumed active management of the CT&V. This ended a process initiated in 1901, when the parent company began unifying operations with the subsidiary (beginning with a single ticket structure). During this period of active management, the B&O built a CT&V rail yard at Canal Dover in 1911.
The B&O fully absorbed the CT&V in 1915.
CT&V operations under the B&O
In the early 20th century, the B&O offered three round-trip passenger trains a day between Cleveland and Canton on the CT&V tracks. One of these continued to Marietta. The high frequency of passenger trains was needed because the B&O's Chicago-to-Jersey City service ran through both Akron and Wheeling. The connection between Cleveland and Akron took on additional importance when, in January 1918, the B&O ceased to run passenger trains through Wheeling, and all of its passenger service went through Akron. The B&O the CT&V line between Akron and Cleveland early in the 20th century to make it a better freight route. However, the rapid availability of the automobile led to severe losses in passenger revenues, and the increasing use of trucks to move bulk goods significantly reduced freight traffic. Passenger service to Marietta ended on July 18, 1933, and passenger service to Valley Junction ended on September 30, 1934.
Slowly, the B&O began reducing the reach of the old Valley Railway. The B&O abandoned the Magnolia Branch in January 1924. It abandoned its track between Valley Junction and Mineral City in 1936, due to construction of the Dover Dam flood control project and realigned another of track to avoid the new reservoir. About of track were also realigned due to construction of the Wills Creek Dam, of track realigned due to construction of the Beach City Dam, and of track realigned due to construction of the Bolivar Dam. The new route involved building a four-span bridge over Sandy Creek. At Mineral City, the CT&V was forced to build two wooden trestles to accommodate flood control projects. One of these was long and crossed a tributary of Huff Run as well as two roads. The CT&V abandoned its main line north of Walnut Street in Massillon due to straightening of the Tuscarawas River, and converted its industrial spur on the city's east side into a new main line. The railroad abandoned and removed the Huff Run Branch from Valley Junction to Mineral City in 1938 following eight years of disuse.
In June 1934, the CT&V moved its passenger station to Cleveland's new Terminal Tower. The 1897 passenger station on Canal Road was converted into a freight depot.
The CT&V realigned the entire route between Beach City and Mineral City and around East Sparta in 1938, to accommodate the Muskingum River Conservation District's flood control initiatives.
Passenger travel on the former CT&V increased somewhat during World War II, but declined sharply again afterward. The B&O ceased all passenger service on the line on December 7, 1962. The last passenger train to run on the old CT&V route was the Cleveland Night Express, which provided overnight service to Baltimore. It abandoned the Newburgh Branch in 1964.
Post-B&O history of the line
The Chesapeake and Ohio Railway (C&O) took control of the B&O on February 4, 1963. The two railroads retained their separate identities until merging into the Chessie System on June 15, 1973.
A scenic railroad began operating on a portion of the old Valley Railway in 1975. The scenic railroad was first conceived in 1967. With little freight and no passenger traffic on the line, Henry Lucas (an official with the Cuyahoga County Fair) and Siegfried Buerling (director of the Hale Farm historic site) suggested that a "tourist railroad" be allowed to use the tracks. The B&O refused. Backers of a scenic railroad continued to press ahead, and in 1975 the Chessie System gave its approval. The Cuyahoga Valley Line Scenic Railroad (now known as the Cuyahoga Valley Scenic Railroad) began operation in June 1975.
The Chessie System merged with the Seaboard Coast Line Railroad in November 1980 to form CSX. In 1984, CSX abandoned the remainder of the Huff Run Branch as well as all of its line between Sandyville and Mineral City.
CSX sales of the line
On September 5, 1984, CSX announced it would abandon the Valley Railway track between Akron and Independence. The National Park Service subsequently began negotiating to buy these of track to add to the Cuyahoga Valley National Recreation Area (which had been established on December 29, 1974, and became a national park on October 11, 2000). The sale was finalized on September 28, 1987. The northern terminus of the Park Service's track is at Independence (Granger Road and Interstate 77, approximately north of the Rockside station), after which CSX resumes ownership of the track. The southern terminus of the Park Service's track is at the Akron station, at which point CSX ownership of the track resumed.
CSX subsequently sold two more portions of the old Valley Railway. In October 1992, CSX sold of track between Canton and Sandyville to a new Wheeling & Lake Erie Railroad (which had recently been spun off by the Norfolk Southern Railway). In May 2000, Akron's METRO Regional Transit Authority purchased of track between Akron and Canton from CSX in May 2000. Metro provides trackage rights to the Cuyahoga Valley Scenic Railroad and two freight railroads, the W&LE and the Akron Barberton Cluster Railway.
CSX still owns and uses for freight the remainder of the Valley Railway (which it calls the Cleveland Terminal and Valley Subdivision) between Independence and Cleveland. It is unclear when the of track between the end of the line (on Whiskey Island) and Literary Road (near W. 3rd Street), or the of track between Valley Junction and Bowerston, was abandoned. The portion between Literary Road and Quigley Road (near Interstate 490), about , was abandoned in 1983. Freight train use of the remaining portion of CT&V Subdivision is light, and as of 1992 the track was not in good enough condition to accommodate passenger trains.
Rebirth of the CT&V Railroad
In 2020, a group of railroad managers re-started the Cleveland Terminal and Valley Railroad as a limited liability company.
The Valley Railway line, as completed
As of 1906, the Valley Railroad had of main track and of secondary track; of main and secondary track siding and yards; of branch and spur track; and of branch and spur track siding and yards. About of track were in the Cleveland city limits.
The railroad had three branch lines: the Huff Run Branch (about from Mineral City east to Lindentree), the Magnolia Branch (about from Sandyville along Sandy Creek to Magnolia), and the Newburg Branch (about from Granger Road, following Mill Creek, to Broadway Avenue).
The railroad had a number of spurs, which served: the Independence stone quarry, the Schumacher "State Quarry" at Deep Lock, the Lawson Waterman quarry at Peninsula, the Lawson Waterman quarry at Deep Lock, the Jaite Paper Mill at Boston Mills, downtown Akron, and the Newburgh Line (through and north of what is now Bacci Park).
The railroad also owned at least three rail yards. The first was the Cleveland terminal yard, built at the end of the line opposite Whiskey Island in downtown Cleveland. It was replaced in 1906 by the B&O Clark Avenue yard on W. 3rd Street. The third rail yard was located in Dover, Ohio. It is unclear when this yard was abandoned.
Historic sites and districts
The Valley Railway Historic District encompasses the former Valley Railway from Independence to downtown Akron. It was added to the National Register of Historic Places (NRHP) in 1985. Much of the railroad runs parallel or adjacent to the Ohio and Erie Canal (added to the NRHP in 1966). The railroad tracks also pass through the Everett Historic District (added to the NRHP in 1993) and the Peninsula Village Historic District (added to the NRHP in 1974) and adjacent to the Boston Mills Historic District (added to the NRHP in 1992) and the Cascade Locks Historic District (added to the NRHP in 1992).
A Valley Railway spur ran to the Jaite Mill Historic District (added to the NRHP in 1979), and the railway also passed close to Hale Farm and Village (added to the NRHP in 1973).
See also
Cleveland railroad history
References
Notes
Citations
Bibliography
Baltimore and Ohio Railroad lines
Rail infrastructure in Ohio
Railway lines opened in 1880
Defunct Ohio railroads
Railway companies disestablished in 1915
1871 establishments in Ohio
Railway companies established in 1871
Cuyahoga Valley National Park | the YVRR carried two presidents: William Howard Taft in October, 1909 and Franklin Roosevelt on July 15, 1938. The National Park Service relocated several surviving structures, including the original hand-turned turntable, from Bagby to El Portal. One of the few surviving pieces of rolling stock, Caboose No. 15, is also located at El Portal. Locomotive 29 also survives, being sold to a Mexican railroad after the YV's closure and is presently on static display in Veracruz, Mexico. Yosemite Valley Railroad The Yosemite Valley Railroad (YVRR) was a short-line railroad operating from 1907 to 1945 in the state of California, mostly | The Yuma Valley Railway was a heritage railroad in Arizona, which formerly operated an excursion passenger train on the rail line following the Colorado River levee between Yuma and Gadsden. The railroad's train has not operated since 2005, when the line was embargoed by the Bureau of Reclamation. The equipment had been parked idle across the canal and south of the Yuma Quartermaster Depot; at least one passenger car was relocated to the Virginia and Truckee Railroad in May 2013.
Motive Power and Rolling Stock
1943 USMC GE 44-ton switcher Center Cab Diesel
1957 GE 65-ton switcher Center Cab Diesel
1952 U.S. Army Davenport-Besler
1922 Pullman chair car (Apache Railway)
1923 Pullman club car/U.S. Army ambulance car
1950 Pullman chair car
History
The YVRY was originally owned by the U.S. Department of the Interior's Bureau of Reclamation. It was part of the Interior Department's irrigation and flood control project along the levee of the Colorado River.
The U.S. Government's railroad was known as the Yuma Valley Railroad and operated from 1914 and into the 1980s. The Yuma Valley Railroad originally extended 25 miles from Yuma to the Arizona/Mexico border town of San Luis. In 1947 the Yuma Valley Railroad was leased to and operated by the Southern Pacific Railroad, at which time the 9 miles from Gadsden to San Luis were idle and later abandoned.
References
Heritage railroads in Arizona
Yuma, Arizona
Transportation in Yuma County, Arizona
History of Yuma County, Arizona | Natural Landmark in 1964, including of the parkland. While logging and industrialization occurred in some parts of the valley in the late 18th and early 19th century, the gorge itself was known for its natural environment, inspiring religious mystics like Johannes Kelpius, writers like Edgar Allan Poe, John Greenleaf Whittier, George Lippard, and William Cobbett; and artists like Thomas Moran, James Peale, William Trost Richards, and Currier and Ives. Wissahickon Valley Park Wissahickon Valley Park contains of parkland in Northwest Philadelphia, including the Wissahickon Creek from its confluence with the Schuylkill River to the northwestern boundary of the city with | Natural Landmark in 1964, including of the parkland. While logging and industrialization occurred in some parts of the valley in the late 18th and early 19th century, the gorge itself was known for its natural environment, inspiring religious mystics like Johannes Kelpius, writers like Edgar Allan Poe, John Greenleaf Whittier, George Lippard, and William Cobbett; and artists like Thomas Moran, James Peale, William Trost Richards, and Currier and Ives. Wissahickon Valley Park Wissahickon Valley Park contains of parkland in Northwest Philadelphia, including the Wissahickon Creek from its confluence with the Schuylkill River to the northwestern boundary of the city with | have since been redesigned to avoid future flood casualties. Woden Valley The District of Woden Valley is one of the original eighteen districts of the Australian Capital Territory used in land administration. The district is subdivided into divisions (suburbs), sections and blocks. The district of Woden Valley lies entirely within the bounds of the city of Canberra, the capital city of Australia. The name of Woden Valley is taken from the name of a nearby homestead owned by Dr James Murray who named the homestead in October 1837 after the Old English god of wisdom, Woden. He named it this | Wilco is a farmer-owned farm supply cooperative dating back to the 1930s (Santiam Farmers Co-op) based in the Willamette Valley of the U.S. state of Oregon. 30 years later, in 1967 Santiam Farmers Co-op merged with 4 other co-ops, the Mt. Angel Farmers Union Warehouse, the Donald Farmers Co-op, the Valley Farmers Co-op in Silverton, and the Canby Cooperative to form "Wilco Farmers Coop". The name "Wilco" comes from a shortening of "Willamette Consolidated".
The cooperative has four divisions — Hazelnut Growers of Oregon, an ag business division that provides customers with crop protection products and fertilizers (Valley Agronomics), a fuels division for commercial petroleum, lubricants, and residential propane delivery and the farm store division.
Today, the farmer-owned cooperative operates 24 retail farm stores throughout Oregon, Washington and California. The retailer carries a wide range of hardware supplies alongside land, lawn, garden, livestock, and pet-related products and services.
The farmer-owned cooperative's headquarters are in Mt. Angel. Hazelnut Growers of Oregon processing plant and headquarters are based in Donald.
In 2011, Wilco launched a program to support local FFA, called FFA Forever, collecting donations from vendors, employees, and customers. As of 2019, the program had collected more than 1 million dollars to benefit the Oregon and Washington FFA Associations.
References
External links
Wilco Coop - Official site
Wilco Farm Store - Official site
Hazelnut Growers of Oregon - Official site
Valley Agronomics - Official site
Agricultural supply cooperatives
Companies based in Marion County, Oregon
Agriculture in Oregon
Mt. Angel, Oregon
American companies established in 1967
Retail companies established in 1967
1967 establishments in Oregon
Agriculture companies of the United States | Jim Smith is an American motocross racer and former NASCAR team owner who helped found the Craftsman Truck Series. Smith tested a prototype of the truck prior to the 1994 Daytona 500 at Daytona International Speedway.
Smith owned Ultra Motorsports until the closing of their shop in early 2006 following a sponsorship dispute with the Ford Motor Company. Ultra Motorsports fielded Dodges in the Craftsman Truck Series for Ted Musgrave and Jimmy Spencer, and was an investment partner with Robby Gordon Motorsports in the NEXTEL Cup Series. Smith won the 2005 NASCAR Craftsman truck series championship with Ted Musgrave driving. Ultra Motorsports won 31 races in the truck series.
Smith is also a two-time winner of the Baja 1000. He owns Ultra Wheel, Inc. in Fullerton, California.
References
External links
Living people
Year of birth missing (living people)
NASCAR team owners | 1,999,760 | Yadkin Valley Railroad The Yadkin Valley Railroad is the trade name of the Piedmont and Atlantic Railroad and is a shortline railroad operating two lines leased from the Norfolk Southern Railway originating out of Rural Hall, North Carolina for a distance of . The railroad began operation in 1989 and is currently a subsidiary of Gulf and Ohio Railways. Primary commodities include poultry feed ingredients, wood products, steel, plastics, propane, ethanol, and rail car storage, amounting to approximately 12,700 annual carloads. Two separate lines comprise the Yadkin Valley railroad, both originating out of Rural Hall. The first runs to North | how many acres of yadkin river bridge is there | what is the largest town in yadkin county nc | who built the yazoo and mississippi valley railroad | how many boardings does yawkey have in boston | where does the first train stop in yass | when was the railroad line in veteran nevada finished | why did the yamhill river start to rise | where is yachats oregon located in the county |
1,999,761 | A Survey of Performance Assessment for Multiobjective Optimizers | Comparing the performance of different evolutive multiobjective algorithms is an open problem. With time, many performance measures have been proposed. Unfortunately, the evaluations of many of these performance measures disagree with the common sense of when a multiobjective algorithm is performing better than another. In this work we present a benchmark that is helpful to check if a performance measure actually has a good behavior. Some of the most popular performance measures in literature are tested. The results are valuable for a better understanding of what performance measures are better. | Stochastic Multiobjective Optimization: Sample Average Approximation and Applications | In multiobjective optimization there is often the problem of the existence of a large number of objectives. For more than two objectives there is a difficulty with the representation and visualization of the solutions in the objective space. Therefore, it is not clear for the decision maker the trade-off between the different alternative solutions. Thus, this creates enormous difficulties when choosing a solution from the Pareto-optimal set and constitutes a central question in the process of decision making. Based on statistical methods as Principle Component Analysis and Cluster Analysis, the problem of reduction of the number of objectives is addressed. Several test examples with different number of objectives have been studied in order to evaluate the process of decision making through these methods. Preliminary results indicate that this statistical approach can be a valuable tool on decision making in multiobjective optimization. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) | Design problems in industrial engineering often involve a large number of design variables with multiple objectives, under complex nonlinear constraints. The algorithms for multiobjective problems can be significantly different from the methods for single objective optimization. To find the Pareto front and non-dominated set for a nonlinear multiobjective optimization problem may require significant computing effort, even for seemingly simple problems. Metaheuristic algorithms start to show their advantages in dealing with multiobjective optimization. In this paper, we extend the recently developed firefly algorithm to solve multiobjective optimization problems. We validate the proposed approach using a selected subset of test functions and then apply it to solve design optimization benchmarks. We will discuss our results and provide topics for further research. | Multiobjective optimization of biorefineries with economic and safety objectives | Many design problems in engineering are typically multiobjective, under complex nonlinear constraints. The algorithms needed to solve multiobjective problems can be significantly different from the methods for single objective optimization. Computing effort and the number of function evaluations may often increase significantly for multiobjective problems. Metaheuristic algorithms start to show their advantages in dealing with multiobjective optimization. In this paper, we formulate a new cuckoo search for multiobjective optimization. We validate it against a set of multiobjective test functions, and then apply it to solve structural design problems such as beam design and disc brake design. In addition, we also analyze the main characteristics of the algorithm and their implications. | AbstractThis article examines the effect of different configuration issues of the Multiobjective Evolutionary Algorithms on the efficient frontier formulation for the constrained portfolio optimiza... | During the past few decades, many global optimisation and multi-objective evolutionary algorithms (MOEAs) have been developed. Those algorithms have shown very useful in enabling system design automation and globally accurate modelling. However, there is a lack of systematic benchmark measures that may be used to assess the merit and performance of these algorithms [1],[2],[3],[7],[8]. Such benchmarks should be consistent with those used in measuring conventional optimisation algorithms, should be simple to use and should result in little program overhead. This paper attempts to formalise, and to promote discussions on, this issue. In this paper, benchmarks in terms of (i) optimality; (ii) solution spread measure; (iii) optimiser overhead will be presented. | 1,999,761 | Various randomized search heuristics have been proposed for multiobjective optimization problems. We need evaluate and compare the performance of these optimizers in order to make good use of them. This paper reviews the theory and methods proposed in the past decade and summarize their characteristics based on relevant literature. However, we didn’t list and analyze many methods proposed before because the relevant literature has done it. We look at them from the classification perspective. These assessment methods are classified as quality indicator based approaches and statistic test approach here. For quality indicators, we further classify them Pareto dominance compliant and non-compliant, unary and binary parameters. This enables us to choose suitable assessment measures in practice. | Single-search-based heuristics for multiobjective optimization | An attempt to classify multiobjective optimization methods | In this paper, an entropy-based metric is presented for quality assessment of non-dominated solution sets obtained from a multiobjective optimization technique. This metric quantifies the ‘goodness’ of a solution set in terms of its distribution quality over the Pareto-optimal frontier. Therefore, it can be useful in comparison studies of different multi-objective optimization techniques, such as Multi-Objective Genetic Algorithms (MOGAs), wherein the capabilities of such techniques to produce and maintain diversity among different solution points are desired to be compared on a quantitative basis. An engineering test example, the multiobjective design optimization of a speed-reducer, is presented in order to demonstrate an application of the proposed entropy metric.Copyright © 2002 by ASME | A Set of Test Cases for Performance Measures in Multiobjective Optimization | Multiobjective Optimum Design Of Structures | Preference Incorporation in Multi-objective Evolutionary Algorithms: A Survey | A Hybrid Metaheuristic for Multiobjective Unconstrained Binary Quadratic Programming | We introduce novel concepts to solve multiobjective optimization problems involving (computationally) expensive function evaluations and propose a new interactive method called O-NAUTILUS. It combines ideas of trade-off free search and navigation (where a decision maker sees changes in objective function values in real time) and extends the NAUTILUS Navigator method to surrogate-assisted optimization. Importantly, it utilizes uncertainty quantification from surrogate models like Kriging or properties like Lipschitz continuity to approximate a so-called optimistic Pareto optimal set. This enables the decision maker to search in unexplored parts of the Pareto optimal set and requires a small amount of expensive function evaluations. We share the implementation of O-NAUTILUS as open source code. Thanks to its graphical user interface, a decision maker can see in real time how the preferences provided affect the direction of the search. We demonstrate the potential and benefits of O-NAUTILUS with a problem related to the design of vehicles. |
1,999,762 | how many people were evacuated from st george in queensland in february 2012 | 2014 Brisbane hailstorm the Bureau of Meteorology described the storm as the worst in a decade. More than 100,000 homes lost power supply. 642 power-lines were brought down. Around 2,000 homes experienced roof damaged caused by hail. 39 people were injured with 12 treated at hospitals. A number of planes were flipped over at Archerfield Airport. More than 12 schools were closed following the storm. Brisbane City Council and State Government buildings suffered $50 million worth of damage. In mid February 2015, it was estimated the storm caused $1.1 billion worth of damage. Many drivers were caught unawares and unable to escape the | hail. According to the Insurance Council of Australia 100,000 insurance claims have been lodged with almost two thirds for vehicles. Hail-damaged cars are expected to be undergoing repairs until the end of 2015. 2014 Brisbane hailstorm The 2014 Brisbane hailstorm struck Brisbane, the capital city of Queensland, Australia on 27 November 2014. The storm caused severe damage to many buildings and cars in the city. Around 40 people were injured. Wind speeds of were recorded with multiple reports of hail in the city and surrounding areas. Warm, humid air over South East Queensland was hit by a cooler southerly change | What started the brisbane floods 2011? | 2010 Victorian storms The 2010 Victorian storms were a series of storms that passed through much of the Australian state of Victoria on 6 March and 7 March 2010. One of the most severe storms passed directly over Greater Melbourne, bringing lightning, flash flooding, very large hail and strong winds to the state's capital. The larger of the storms brought heavy rain and large hail, which led to flash flooding, disrupting transport in central Melbourne and central Victoria throughout the weekend. Many residential buildings were damaged, most due to hail and heavy rain. Some major buildings were evacuated including Flinders | Cyclone Joy Queensland on 26 December. It dissipated the next day; remnant moisture continued as torrential rainfall over Queensland for two weeks. While drifting offshore northeastern Australia, the cyclone produced wind gusts as high as in Cairns, strong enough to cause power outages. In Mackay, a tornado spawned by Joy damaged 40 homes, while torrential rainfall just south of the city peaked at over . Most storm-associated damage was wrought by severe flooding, which persisted for weeks in hardest-hit locations. Rains significantly increased water levels on 10 rivers, among them the Fitzroy River, which discharged about of freshwater into Keppel Bay over | Climate change in Australia overall not as wet as 1974 or even 2000. In New South Wales and Queensland, however, the years 1886–1887 and 1889–1894 were indeed exceptionally wet. The heavy rainfall over this period has been linked with a major expansion of the sheep population and February 1893 saw the disastrous 1893 Brisbane flood. A drying of the climate took place from 1899 to 1921, though with some interruptions from wet El Niño years, especially between 1915 and early 1918 and in 1920–1921, when the wheat belt of the southern interior was drenched by its heaviest winter rains on record. Two major El | 2010–11 Queensland floods tremendous 'Aussie spirit' and that, "... right across Queensland today people have got up, they've marched out of their homes and they've gone to find people to help. It's a tremendous spirit of volunteering right across Queensland ...". Prime Minister of Australia Julia Gillard toured flood-affected areas on 31 December, the day before The Queen (Elizabeth II), sent her expressions of concern and sympathy for the victims of the floods to her representative in Queensland, Governor Penelope Wensley. The Queen later made a donation to her Queensland premier's flood relief appeal, as did her son, The Prince of Wales. In | 2010–11 Queensland floods an estimated 20,000 homes would be affected when the river peaked on 14 January. He subsequently advised that the Brisbane River transport infrastructure had been "substantially destroyed". The Brisbane River peaked on 13 January at a lower level than predicted, but still 20,000 houses in Brisbane were inundated. Some of the Brisbane suburbs worst affected by the floods were St Lucia, West End, Rocklea and Graceville. The floods damaged some of Brisbane's icons. The Brisbane Riverwalk, a floating walkway over the Brisbane River linking the inner city neighbourhoods of Fortitude Valley and New Farm, broke up, with a section forming | 1,999,762 | St George, Queensland metres, and again in December 2010 - January 2011. Flooding once again occurred in February 2012. When there was a possibility of the river reaching 15 metres, about 2000 residents were mandatorily evacuated on 4 and 5 February to evacuation centres in Dalby and Brisbane. A temporary levee was built in St George on the morning of 5 February (Sunday). The Balonne River reached a height of 13.85 metres on Tuesday 7 February. St George has the following heritage-listed sites: The town is a centre for cotton growing, as well as sheep and wheat. St George gained national attention with | how many people visit st george's market daily | who did the settlers arm at the battle of st george's caye | when did st george's open in preston | where is the george river in canada located | when was st george's settled in bermuda | when was st george's park in port elizabeth built | which town on the georges river was founded by bass and flinders in 17 | when did st george's cave change its name |
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1,999,764 | Research on New Construction of Double PID Hydro Turbine Governor |
Introduction
Small Hydropower Plants (SHPs) are objects up to 10MW. The SHPs are mainly the run-of-the-river schemes, where the water storage is limited or impossible. Therefore, the operating parameters are influenced by the actual hydrological conditions. In order to improve the object profitability, the operating range of the turbine discharge needs to be maximal and the average efficiency of the energy conversion have to be possible high [1]. The standard turbine solutions implementing double regulation (e.g. Kaplan turbine) are relatively expensive and can be replaced by the simple propeller turbine working at variable speed [2]. The variable speed operation is provided by the power electronic converter (PEC) that matches electrical energy of the generator with power system requirements [3]. In order to improve the overall system efficiency, the permanent magnet synchronous generator (PMSG) can be used. The PMSG allows to eliminate the mechanical transmission gear by construction with high pair pole numbers, what decreases the generator nominal speed. Furthermore, the simple propeller turbine and flexible generator construction allows to integrate these two elements into one unit, what simplify the hydro-set construction [4].
The hydro-set containing propeller turbine integrated with electrical generator is not well investigated yet. In order to support the design process and determine the operating conditions the detailed modeling is required. The computational fluid dynamics (CFD) technique seems to be the most suitable taking into account qualitive and quantitive results and analysis of the fluid flow machines of complex geometries [5]. However, it requires a properly defined calculation model, which includes: precise geometry, proper grid generation, suitable turbulence model and correct boundary conditions [6].
The paper presents the CFD analysis using three turbulence models. First is the k-ε realizable model providing good performance for flows with rotation and adverse pressure gradients influencing the boundary layers [7,8]. The second analyzed model is k-ω SST (Shear-Stress Transport), which combines standard k-ω model near the wall and k-ε model in the outer portion of the boundary layer. It gives the accurate results for flows with adverse gradient pressure (flows with separation), therefore it is reliable for turbines [9,10]. Finally, the one-equation Spalart-Allmaras turbulent model is applied. This is a robust model suitable for mildly complex flow under pressure gradient (airfoils, wings). By applying the Wall Treatment technique, it is also applicable in fluid flow machines with low grid resolution of boundary layer [11]. The hydro-set model is prepared and analyzed in Ansys Fluent v18.0 [12].
Numerical modelling
Geometry description
The analyzed scheme is the run-of-the-river SHP, which is situated in a bypass of the overfall weir. The crosssection of the SHP is presented in fig. 1. The SHP contains an axial-flow propeller turbine integrated with the permanent magnet synchronous generator (PMSG) [13]. The turbine is located in the generator rotor. The permanents magnets are mounted outside the rotor ring. The hydro-set contains also the guide vanes that controls the water volume flowing through the turbine ( fig. 2). The fundamental and operating parameters of the modelled turbine are given in Table 1 [14].
Mesh grid generation
The computational mesh was prepared in ANYS Meshing application based on the CAD model (Fig. 3.) for non-conformal components: the inlet pipe, hydroset tube that includes the guide vanes and the draft tube. The components were selected considering structure details in order to optimize the mesh. Additionally, to eliminate the computational complexity of the remeshing function the turbine rotor was prepared as a separate component. The curvature size function with a curvature normal angle equals 20° and maximal mesh element of 30 mm was applied. Additionally, due to the significant geometry complexity of the guide vanes and rotor the element size was reduced to 20 mm. The resulted mesh model is presented in Fig. 4. The generated mesh consists of about 1.2 million elements. The mesh quality was assessed using orthogonal quality and skewness parameters. The average value of the orthogonal quality equals 0,745 while the average skewness is 0,266. Both parameters satisfy the recommended values (orthogonal quality > 0.005, skewness < 0.98) for fluid flow calculations [1].
The calculations were performed for the three different models: Spalart-Allmaras, k-ε realizable and kω SST. The model convergence was assessed by the residuals, which measure the discretized equation solution inaccuracy [15]. The obtained residual curves show that the solutions of all models are converging to the exact solution after 50-100 iterations. The fastest stabilization provides the Spalart-Allmaras model, however some variations are presented in the obtained results.
Boundary conditions and solver settings
At the location of the inlet boundary condition the total pressure (152600 Pa) is given, which is the sum of the static pressure and dynamic pressure. The static pressure (149885 Pa) is defined by the hydrostatic head at the inlet (4,95 m), while the dynamic pressure (2715 Pa) results from the velocity of the fluid at the inlet (2,33 m/s). At the outlet boundary the backflow pressure (125360 Pa) caused by the hydrostatic head at the outlet (2,45 m), is specified (Fig. 5).
The pressure based solver allows to perform calculations of the fluid flow problems using separate or split equations. In case of the transient fluid flow, complex mesh grid or large time steps, the more accurate results are obtained by using the coupled algorithm. The most important solver parameters are listed in Table 2.
Results and discussion
The calculation results of the CFD model for the three turbulence models are presented in Figure 6 in the form of power as function of turbine speed. Two values of the guide vanes angles are analyzed: 30° and 60°, where 0° corresponds to the close guide vanes.
Presented curves indicate the significant divergence of the calculation results. The turbulence model selection influences the average value of the power and also the speed for which the power is maximal.
The axial velocity distribution of hydro-set for both guide vane angles (30° and 60°) are presented (Fig. 7). It can be seen that velocity increases with the guide vane angle increase, which is due to increases in discharge. It is seen that the flow is smooth for nominal guide vane angle (60°), whereas there is significant velocity gradient at guide vanes for lower angle (30°).
Conclusions
This paper determines the mechanical characteristics of a propeller turbine integrated with an electrical generator, operating at a variable rotational speed in a small hydropower plant, using the ANSYS Fluent software. For this purpose, a geometric model of the fluid domain was prepared. The numerical mesh was created that met the requirements of flow problems, and then using the available models of turbulence and calculation methods the characteristics are determined. The k-ε and k-ω SST models, as well as the and one-equation Spalart-Allmaras (SA) model, were tested. The SA model is preferred in the fluid flow calculations of flow machinery when the boundary layer mesh resolution is low. An additional advantage of using SA model is the shortened calculation time, which is especially crucial for variable time-dependent flows and large mesh models.
The simulations proved that the modeling methodology in the ANSYS FLUENT software can be successfully used in the process of designing and optimizing rotating machines, and in particular the facilities for which the prototyping is done. This mainly applies to prototype objects, to which practically every new hydropower plant can be calculated. At the stage of turbine design due to high acceleration resulting from the application of numerical methods, it is possible to analyze much more design variants at the same time and select the best option. Simultaneously, such a solution also brings financial benefits because in the numerical analysis only the computer model is changed and optimized, so there is no need to produce expensive prototypes every time the model changes.
Fig. 1 .
1SHP cross-section.
Fig. 2 .
2Main elements of hydro-set.
Fig. 3 .
3SHP cross-section.
Fig. 4 .
4SHP cross-section.
Fig. 5 .
5Boundary conditions scheme.
Fig. 6 .Fig. 7 .
67Power as a function of turbine speed. Distribution of the axial velocity in the hydro-set for 60° (a.) and 30° (b.) of the guide vane angle.
Table 1 .
1Setting Word's margins.Parameter (Unit)
Value
Net head (m)
2.75
Discharge (m3/s)
3
Rotational speed (rpm)
300
Output power (kW)
75
Runner diameter (m)
0.95
Number of runner blades
4
Number of guide vanes
12
Table 2 .
2Solver settings and model relaxation factors.Solver Parameter
Value
Pressure-Velocity Coupling
Coupled
Discretization of Gradient
Least Squares
Cell Based
Discretization of Pressure
Presto
Discretization of Momentum
Second order
Upwind
Discretization of Turbulent
Viscosity
Second order
Upwind
Transient Formulation
Second Order
Implicit
Flow Courant number
100
Momentum and Pressure Explicit
Relaxation Factor
0.75
Density and Body Forces Under-
Relaxation Factors
1
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). MATEC Web of Conferences 240, 05002 (2018) https://doi.org/10.1051/matecconf/201824005002 ICCHMT 2018
MATEC Web of Conferences 240, 05002 (2018) https://doi.org/10.1051/matecconf/201824005002 ICCHMT 2018
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| Design and Construction of Mini Hydropower Plant with Propeller Turbine | The invention discloses a cone spiral roller water flow power machine assembly, belonging to the technical field of new energy. The power machine assembly is arranged in a riverway with a natural flow, and is in a floating state; the flow of the riverway is utilized for impacting the spiral roller power machine assembly; and the machine assembly integrally rotates to generate power. | sufficient water flow. Large Kaplan turbines are individually designed for each site to operate at the highest possible efficiency, typically over 90%. They are very expensive to design, manufacture and install, but operate for decades. They have recently found a new home in offshore wave energy generation, see Wave Dragon. The Kaplan turbine is the most widely used of the propeller-type turbines, but several other variations exist: Kaplan turbine The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted |
Introduction
The Engineery Mechanic Programme at the Pontificia Bolivariana University was initiated in 2002, and a hydraulic machine is an important component of the curriculum which aims to provide an understanding of the physical principles involved in energy generation. To this end, the construction and test of an impulse turbine was devised to demonstrate the technology of Pelton turbines in hydropower plants.Hydroelectric generation plays an important role in global energy supply. For example, in 2010 it accounted for almost 16% of global electricity generation [1]. It's a renewable energy source because Earth´s water cycle is driven by solar energy. The Pelton turbine, which was patented by Lester Pelton in 1880, is commonly used in hydroelectric generation in geographical locations where high water head is available but volume flows are small.
The water flow is directed by one or more nozzles to strike the ridge of each vane tangentially in succession and in turn delivers the water´s kinetic energy in impulses. Therefore, the turbine is classified as an impulse turbine. In principle, the ridge acts to divide the water jet in order to achieve better mechanical efficiency. With an optimised jet and cup geometry, more than 90% of the power of the water jet can be transformed into mechanical power at the turbine shaft [2]. Since the Pelton wheel rotates in air, the action of the water and wheel rotation is easily observed by the experimenter. Direct observation of efficiency changes is an attractive characteristic from an educational perspective and it is said that Pelton himself got the idea for his turbine from such a direct observation [3].
R e t r a c t e d
Theory
The total extractable power of a water jet P h can be found from [4] gho
P h (1)
Where ρ is the density of water, g the acceleration due to gravity (9.81 m/s 2 ), h the available head of the water source and Q the volumetric water flow rate. The speed of the water jet C is found from the flow rate and the cross-section area A of a circular nozzle with diameter D
C= Q/A = 4Q/(π D 2 ),(2)
The mechanical power P a available at the turbine shaft can be determined by measuring the torque T on the shaft at a corresponding angular speed ω. The torque is found by measuring the tangential force F on a brake lever with moment arm length l (see figure 1).
The angular speed ω is equal to the tangential speed of the turbine U divided by the pitch radius R of the Pelton wheel
ω = U / R(4)
The mechanical efficiency of the turbine describes how effectively the available kinetic energy of the water jet is transformed into turbine motion and from (1) and (3) is Cup and jet design are important parameters and it can be shown [5] that maximum theorical mechanical efficiency is achieved when the tangential speed of the turbine is roughly one-half the speed of the water coming from the jet or
η m = P h / P a(5)
When the turbine shaft is coupled to an electric generator which supplies electricity to a variable resistive load R (see figure 2), the electrical power P e of the load is
P e = IV(7)
In which I is the load current and V the voltage across the load. The electrical efficiency η e of the generator and the overall efficiency η 0 of hydroelectric generation are then η e = P e /P a (8) η o =P e /P h (9)
Methodology
The Pelton turbine consists of a cylindrical hub onto which 16 vanes (see figure 3) have been fastened using screws and right angle aluminium brackets. The hub and vanes were made of aluminium for easy machineability and resistance to the oxidation. The pitch radius of the turbine, which is the distance from the centre of the shaft to the centre of the impact point of the water jet (160 mm in this case), should be roughly 10 times the diameter of the jet (16 mm in this case) so that adjacent vanes do not interfere with the water flow [2]. For the turbine under discussion measured rotation speed have been in the range of 100 -500 rpm with turbine power in the range of 20 -150 W. Has been conducted experiments with the Pelton turbine using three different water volume flow rates, referred to as Q 1 , Q 2 and Q 3 . The water pressure p at the nozzle is measured for each Q value with the turbine shaft rotating freely.
The relationship between the tangential force on the shaft and the speed of rotation is then determined using the brake lever for each Q value. This relationship is generally found to be of a linear nature in the range of variables described ( figure 3).
With the drive belt connected to the DC generator and the brake lever removed from the turbine shaft, the current and voltage of the resistive load are measured, while simultaneously measuring the rotational speed of the turbine. This is repeated for several values of load resistance. The measurement yields the electrical power produced by the generator as a function of rotational speed.
Using experimental data, the mechanical, electrical and overall efficiency of the hydroelectric plant are calculated for each Q value. Table 1 lists the Q values used, followed by the corresponding hydraulic power calculed from equation (1) using a net head available of 4 m. The corresponding maximum mechanical and electrical (5)) as a function of rotation speed is plotted in figure 4.
Results and discussion
Conclusion
A laboratory-scale Pelton turbine for hydroelectric generation has been constructed and used in the educational curriculum of the Engineering Mechanical Programme at the Pontificia Bolivariana University. From the experimental results, the turbine was found to have a maximum mechanical efficiency of 0.6 ± 0.03 for a flow rate of 2.1 l/s. The Pelton turbine demonstrate the principles of hydropower and are well suited in the education of students of Mechanical Engineering.
Figure 1 .
1Measurement of the torque on the turbine shaft.
Figure 2 .
2Pelton wheel water turbine experiment.
Figure 3 .
3Pelton wheel.
Figure 4 .
4The mechanical efficiency of the Pelton turbine as a function of the speed of rotation.
2nd International Meeting for Researchers in Materials and Plasma Technology IOP Publishing Journal of Physics: Conference Series 466 (2013) 012036 doi:10.1088/1742-6596/466/1/012036 efficiencies are on the right side of the table along with the maximum total efficiency of the laboratory-scale hydroelectric plant. The mechanical efficiency of the turbine (equation3
R
e t r a c t e d
Table 1 .
1The three Q values used in the experiment.Q [l/s]
Ph [W]
Pa [W]
Pe [W]
η m [W]
η o
Q 1 = 2.5
98
44.1
19.6
0.45
0.20
Q 2 = 2.1
82.3
49.4
18.9
0.60
0.23
Q 3 = 1.5
58.8
29.4
8.82
0.50
0.15
International Energy Agency (IEA) 2010 Key world energy statistics. París: SoregraphInternational Energy Agency (IEA) 2010 Key world energy statistics (París: Soregraph)
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American Society of Mechanical Engineers 1991 The Pelton water wheel collection. Grass Valley (CA; North Star Power House MuseumAmerican Society of Mechanical Engineers 1991 The Pelton water wheel collection. Grass Valley (CA: North Star Power House Museum)
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10.1088/1742-6596/466/1/0120362nd International Meeting for Researchers in Materials and Plasma Technology IOP Publishing Journal of Physics: Conference Series. 466120362nd International Meeting for Researchers in Materials and Plasma Technology IOP Publishing Journal of Physics: Conference Series 466 (2013) 012036 doi:10.1088/1742-6596/466/1/012036
| The results of strength and dynamic characteristics analyses for head cover of a large axial flow turbine show that the original structure has serious structural problems and poor dynamic characteristics,so that the resonance is most likely to occur.Proposed improvement scheme has better strength performance and dynamic characteristics,and it meets strength and dynamic characteristics of the design requirements. | Mărişelu Hydro Power Plant is a large power plant on the Someşul Cald river situated in Romania.
The project was started and finished in the 1980s and it was made up by the construction of a rockfill dam high which was equipped with three hydrounits, the hydropower plant having an installed capacity of 221 MW.
The power plant generates 560 GWh of electricity per year.
See also
Porţile de Fier I
Porţile de Fier II
External links
Description
Hydroelectric power stations in Romania
Dams in Romania | short video explaining the concept was completed in October 2013 and made available in English on YouTube and in Chinese on Youku. Dynamic tidal power Dynamic tidal power or DTP is an untried but promising technology for tidal power generation. It would involve creating a long dam-like structure perpendicular to the coast, with the option for a coast-parallel barrier at the far end, forming a large 'T' shape. This long T-dam would interfere with coast-parallel tidal wave hydrodynamics, creating water level differences on opposite sides of the barrier which drive a series of bi-directional turbines installed in the dam. Oscillating | 1,999,764 | In this article the author proposes a new construction of hydro turbine governor, which uses additional PID control on governor, then analyzes the new construction of turbine governor with MATLAB. At last the author gives the result that the quality of the governor using this new construction can be improved greatly. | Design of an optimal robust governor for hydraulic turbine generating units | Integrated maintenance features of hydro turbine governors | A Detailed Governor-Turbine Model for Heavy-Duty Gas Turbines With a Careful Scrutiny of Governor Features | A New Turbine Governor Model Including Unit Plant Coordinated Control System and Its Application | Application of Spring Center Speed Governor to Generators with High Water Head and High Rotational Speed | Performance optimization of primary frequency regulation based on modeling of turbine and its governing system | A CONTROL METHOD FOR SIMULTANEOUS TRACKING OF ROTATE SPEED AND LOAD OF A TURBINE GENERATOR | Installation of an integrated turbine-generator control system for a pulp mill |
1,999,765 | Does sniffing glue even 1 time damage elements of your brain? | How does inhaling burning plastic affect you? | Do the effects of piggy bank, cracked piggy bank, and broken piggy bank stack when you have them all in your accessory bag? Itchy reforge on all of them. | Aerosol “sniffing,” a variant of glue “sniffing,” involves the deliberate inhalation of aerosol products and propellants. Approximately 65 deaths have been attributed to this practice. They have been predominantly sudden and generally lack conclusive autopsy findings. The cause of death has not been defined in most cases; however, various mechanisms have been postulated. The evidence suggests acute cardiac arrest as a frequent cause. It could result from the sudden onset of ventricular fibrillation due to sensitization of the heart to epinephrine by inhalation of high concentrations of aerosol contents. Experimental investigation revealed that the commonly used aerosol propellants, in high concentrations, are capable of sensitizing the heart to epinephrine resulting in serious cardiac arrhythmias. Therefore, it is concluded that cardiac sensitization is a likely mechanism of death in many of the aerosol-sniffing fatalities. | Hey guys,
So I just recently cleaned my Juul, rubbing the pins with a q-tip with 70% isopropyl alcohol, and then drying with the other side of the q-tip as much as I could. I took a rip maybe 30 secs later and thought it tasted different. It could have just been the fact that it was a bit dirty before, but my anxiety ridden mind immediately went to the isopropyl alcohol. Should I be concerned that possibly a bit was left in there that I didn't get? What harm could that have caused? Has this ever happened to you before? | Early Maintenance of Hippocampal Mossy Fiber–Long-Term Potentiation Depends on Protein and RNA Synthesis and | it's alright. Applied it on my white canvas shoes and does keep liquids from staining it. Doesn't prevent scuffing from coming in contact w solid objects though. Also has a very strong chemical odor that wafts up from my feet when sitting down. | common drug screens, it has caused the instantaneous deaths of numerous individuals by precipitating fatal cardiac arrhythmia. Several reports of fatal car crashes have been linked to drivers huffing 1,1-difluoroethane. Because of inhalant abuse, a bitterant is often added to consumer canned air products. In a DuPont study, rats were exposed to up to 25,000 ppm (67,485 mg m) for six hours daily, five days a week for two years. This has become the no-observed-adverse-effect level for this substance. Prolonged exposure to 1,1-difluoroethane has been linked in humans to the development of coronary disease and angina. Though not extremely flammable | Flame retardant burn injuries in children, the risks of thyroid disruption as well as physical and cognitive developmental delays, are not outweighed. A study was conducted by Carignan in 2013, C. et al. found that gymnasts are exposed to some flame-retardant products such as PentaBDE and TBB more than the general population in the United States. After testing hand-wipe samples before and after the exercise, they found that the BDE-153 concentration was four to over six times greater among gymnasts than the United States population. Also, the PentaBDE concentration was higher up to three times after exercise compared to the level before; | 1,999,765 | So im a idiot. I sniffed glue. I was goofing off and i randomly thought "Hey lets sniff glue lets see if anything happens" and i actually fucking sniffed it. It felt really good for like a milliseconds but then a huge headache came on. I read about how sniffing glue can damage the brain. What i really want answered is if glue can damage parts of my brain even 1 or 2 times. Does it depend on my age? Does it depend on any prexisting conditions i have have? I would really like an answer to that. Googling if it causes brain damage in the short term only gives vague responses that dont answer my question at all. Thanks if anyone can answer this. And yes i know im a fucking idiot for sniffing glue. Dont need to remind me. | Glue is dangerous to pets | Is glue a drug worth trying or inhaling? | Is it bad to use glue on pieces from a bong? | Not sure if this is true for all aquarium glue ... | Dangers of super glue for cuts? | ALL GLUE LET GO...DANGEROUS | This works where others (including Super Glue) fail | Used hot glue to hold my bong together, could this potentially be hazardous? also possible stoner tip I guess maybe |
1,999,766 | While I enjoyed portions of the book | was fully engrossed and entertained the whole book. I had to start the second one minutes after finishing the first. | I enjoyed reading the book most of the time. Some parts I just put it down because I didn't want to go on. All in all I think it was a good book. | Thoroughly enjoyed it. I read the book in it's entirety in six hours because of how interesting it was. Definitely a interesting read. | Enjoyed it. But not happy split into multiple books. I didn't get the rest. | It was a good book. It was long in some parts, but overall I enjoyed it. | Parts of the book were very interesting, but certain areas were a bit boring. | I enjoyed it until the reason for the whole thing was revealed. I thought it was a bit of a stretch. Still an enjoyable quick read. | I like the parts that helped me understand what he was thinking but a lot of the book is exactly the same as reading 1st 50 shades book. | 1,999,766 | Expected a book about a City dweller rebuilding his life (after divorce) in a new village. While I enjoyed portions of the book, large portions were dedicated to cricket matches which I have no interest in and skimmed over. | Reading this book reminded me how much I loved cricket and how much I miss it now | More than a cricket book | Another Classic Baseball Novel | Books that talk more about the culture, history and cricket as a whole than an autobiography of one person's career? | Brilliant baseball book | A book every baseball fan should read | Seeking the Perfect Game: Baseball in American Literature | Great entry book into the sports |
1,999,767 | Looking for Bicycle shops ready to convert my mountain bikes, into ebike | I am new to the area and am looking to do some upgrades for my mountain bike. I live in the Towson area and wouldn't mind traveling a little bit for a decent price and decent work. What shops would you suggest? | hi people, i would love if any of you could help me out... i´ve been searching a lot for the best quality ebike to import and sell, mostly chinese bikes.
They all seem to have really similar specifications.
any suggestions? or links to the page of a good manufacturer
thanks!!! | Anyone know where I can trade in two gently used mountain bikes for one used road bike? | Looking for a solid bike shop to give my bike a once over, trying not to pay too much. Any recommendations? | Anyone have any good bike shops in Seattle to recommend? I’m looking to face and ream a brand new frame I’m working on. Potentially looking for bike shops with such equipment and experience. As I’m new to town, looking for your advice! | I have been (off and on) researching ebikes for my specific needs. I have looked into cargo bikes, radwagon, Aosom Elite II trailer, and DIY setups, and I am trying to narrow down the information. I currently just have a normal street bike and a bus/train pass. The hardest reselling items to bring are those vintage electronics like 50 lb receivers (have to pass or get assistance from friends if the profit is really high).
Additionally, the weight of the items (even just smaller things + bike chain all in a backpack) can be draining on 15+ mile trips. Plus I need a bike that can go on longer trips and I am actively resisting the urge of getting a car.
Here is a list of specific items:
* Range 30-50 miles, can add additional batteries if needed
* Protection of cargo from water, not a deal breaker because I can pack heavy duty trash bags but it would be a nice feature
* Ability to carry items like gaming systems, vintage receivers, and potentially furniture
* Security: I will stop at places that I go inside, so additional security is always welcomed
What advice/tips do you have? | I have a dirt jumping mountain bike that I am looking to trade in for a mountain bike that I can ride around the city and surrounding parks (looking for a lighter bike). I am wondering if anyone can give me their thoughts on where I can get the best deal for trade-ins.
Thanks | I'm interested in building myself an ebike. Are you into ebikes? Do you know someone or some place where I could meet up with someone that knows the ropes and buy them a beer to pick their brains? | 1,999,767 | I wish to convert my families' Bicycles into e-bikes, by means to install a (rechargeable)battery powered front wheel, for hybrid power (pedals and or just e-motor), which bike shops are ready to do this for me and at what cost? I am willing to shell upwards of $500 per wheel/bicycle.
available power range has to be at least 20~25 km between charges of no more than ~6 hrs inbetween.
can anyone share your experience with these? purpose is for commute to work and back, ease against strong headwinds, occasional uphill, or assisted starts off the stop line particularly turning with traffic via intersections. | Why hybridization of energy storage is essential for future hybrid, plug-in and battery electric vehicles | Finding Power Wheels batteries | This paper presents a study related to Hybrid Electric Motorcycle (HEM) with a front wheel DC electric hub motor using Lithium Ion battery that renovated from Honda Lead 110cc. The rear wheel is driven by drive train integrated with a continuously variable transmission (CVT) as its origin. Both of them are able to provide propulsion torque separately or simultaneously. Fuel consumption and performance characteristics of the proposed design will be evaluated by a dynamic simulation model in Matlab/Simulink. The obtained results show that plug - in hybrid structure without generator is the most feasible and effective choice to renovate a traditional scooter in traffic condition of many populous cities in Vietnam. The study also illustrated fuel economy can save up to 21.1% with the same performance characteristics between the plug - in hybrid scooter and original one. | BMX e-Bike Build In Progress: Looking for Battery Recommendations | Anyone done an eBike conversion? | Battery recommendation for Vulcan & Stampede | Convert bike to ebike or buy new? | Help! New to E-Bikes and looking for one with range |
1,999,768 | of mixture composition oscillations on a strained premixed methane/air flame. The problem is of practical relevance in direct-injection spark-ignition (DISI) engines and gas-turbines, in which premixed flames propagate through temporally and spatially stratified mixture field. The primary focus of the study is to identify the dynamic flammability limit, defined as the minimum instantaneous mixture equivalence ratio that can sustain flame propagation. It is shown that the dierence between the dynamic and steady flammability limits, `t i`s, represents the extension of the flammability limit under unsteady condition, and is a function of the mean strain rate, frequency of oscillation, and mean equivalence ratio. A proper normalization is proposed in order to scale the dynamic flammability limit extension as a function of a nondimensional frequency. As an improvement from previous studies, the use of time scale based on the actual flame thickness and speed represents the correct physical time and length scales involved in the process, thereby yielding a good collapse of the data. As a related subject, a universal extinction criterion for unsteady flames is proposed based on the local Karlovitz number defined as the ratio of the local reaction time to the characteristic flow time. The results show that the maximum local Karlovitz number at the dynamic flammability limit is approximately constant, irrespective of strain rate, mean equivalence ratio, and frequency of oscillation. The results thus extends earlier studies on the local Karlovitz number in steady flame extinction. | ABSTRACTThe influences of initial mixture distribution on localized forced ignition of globally stoichiometric stratified mixtures have been analyzed using three-dimensional compressible direct numerical simulations. The globally stoichiometric mixtures (i.e., ) for different root-mean-square (rms) values of equivalence ratio (i.e., = 0.2, 0.4, and 0.6) and the Taylor micro-scale of equivalence ratio variation (i.e., 2.1, 5.5, and 8.3 with being the Zel’dovich flame thickness of stoichiometric mixture) have been analyzed for different initial rms values of turbulent velocity . The equivalence ratio variation is initialized following both Gaussian and bi-modal distributions for a given set of values of and in order to analyze the effects of mixture distribution. The localized forced ignition is accounted for by considering a source term in the energy conservation equation that deposits energy for a stipulated time interval. It has been demonstrated that the initial equivalence ratio distribution has signif... | Abstract The burning rate in the vicinity of a piston is estimated from a fractal analysis. The fractal parameters are determined from laser sheet tomography flame images for methane–air mixtures with three equivalence ratios (1, 0.9, 0.8) in a transparent spark-ignition engine. Two imaging configurations were used: five horizontal planes placed at different distances from the piston (0, 1, 2, 3, and 5 mm) and a vertical one passed through the center of the combustion chamber. The methodology proposed by Foucher et al. [F. Foucher, S. Burnel, C. Mounaim-Rousselle, Proc. Combust. Inst. 29 (2002) 751–757] allows the effect of cyclic variations to be avoided. The fractal formulation is modified to take into account the flame–piston distance and flame quenching. Far from the piston, evolution of the fractal dimension versus q ′ / S L 0 is found to be in good agreement with literature results. Near the piston, the fractal dimension evolves significantly when the distance is about twice the integral length scale and tends toward 2, the fractal dimension of a laminar flame front. The quenching ratio parameter Q R is introduced to consider the quenching of the flame by the piston. Finally, the burning rate is determined as a function of the distance between the wall and the mean flame contour and compared to a flame density approach, and similar results are found. | Mixtures of dispersed combustible materials (such as gaseous or vaporised fuels, and some dusts) and oxygen in the air will burn only if the fuel concentration lies within well-defined lower and upper bounds determined experimentally, referred to as flammability limits or explosive limits. Combustion can range in violence from deflagration through detonation.
Limits vary with temperature and pressure, but are normally expressed in terms of volume percentage at 25 °C and atmospheric pressure. These limits are relevant both to producing and optimising explosion or combustion, as in an engine, or to preventing it, as in uncontrolled explosions of build-ups of combustible gas or dust. Attaining the best combustible or explosive mixture of a fuel and air (the stoichiometric proportion) is important in internal combustion engines such as gasoline or diesel engines.
The standard reference work is still that elaborated by Michael George Zabetakis, a fire safety engineering specialist, using an apparatus developed by the United States Bureau of Mines.
The highest concentration of a gas or vapor (percentage by volume in air) above which a flame will not spread in the presence of an ignition source (arc, flame, or heat). Concentrations higher than UEL are “too rich” to burn.
Violence of combustion
Combustion can vary in degree of violence. A deflagration is a propagation of a combustion zone at a velocity less than the speed of sound in the unreacted medium. A detonation is a propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium. An explosion is the bursting or rupture of an enclosure or container due to the development of internal pressure from a deflagration or detonation as defined in NFPA 69.
Limits
Lower flammability limit
Lower flammability limit (LFL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower explosive level (LEL). At a concentration in air lower than the LFL, gas mixtures are "too lean" to burn.
Methane gas has an LFL of 4.4%. If the atmosphere has less than 4.4% methane, an explosion cannot occur even if a source of ignition is present. From the health and safety perspective, the LEL concentration is considered to be Immediately Dangerous to Life or Health (IDLH), where a more stringent exposure limit does not exist for the flammable gas.
Percentage reading on combustible air monitors should not be confused with the LFL concentrations. Explosimeters designed and calibrated to a specific gas may show the relative concentration of the atmosphere to the LFL—the LFL being 100%. A 5% displayed LFL reading for methane, for example, would be equivalent to 5% multiplied by 4.4%, or approximately 0.22% methane by volume at 20 degrees C. Control of the explosion hazard is usually achieved by sufficient natural or mechanical ventilation, to limit the concentration of flammable gases or vapors to a maximum level of 25% of their lower explosive or flammable limit.
Upper flammability limit
Upper flammability limit (UFL): Highest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). Concentrations higher than UFL or UEL are "too rich" to burn. Operating above the UFL is usually avoided for safety because air leaking in can bring the mixture into combustibility range.
Influence of temperature, pressure and composition
Flammability limits of mixtures of several combustible gases can be calculated using Le Chatelier's mixing rule for combustible volume fractions :
and similar for UFL.
Temperature, pressure, and the concentration of the oxidizer also influences flammability limits. Higher temperature or pressure, as well as higher concentration of the oxidizer (primarily oxygen in air), results in lower LFL and higher UFL, hence the gas mixture will be easier to explode.
Usually atmospheric air supplies the oxygen for combustion, and limits assume the normal concentration of oxygen in air. Oxygen-enriched atmospheres enhance combustion, lowering the LFL and increasing the UFL, and vice versa; an atmosphere devoid of an oxidizer is neither flammable nor explosive for any fuel concentration (except for gases that can energetically decompose even in the absence of an oxidizer, such as acetylene). Significantly increasing the fraction of inert gases in an air mixture, at the expense of oxygen, increases the LFL and decreases the UFL.
Controlling explosive atmospheres
Gas and vapor
Controlling gas and vapor concentrations outside the flammable limits is a major consideration in occupational safety and health. Methods used to control the concentration of a potentially explosive gas or vapor include use of sweep gas, an unreactive gas such as nitrogen or argon to dilute the explosive gas before coming in contact with air. Use of scrubbers or adsorption resins to remove explosive gases before release are also common. Gases can also be maintained safely at concentrations above the UEL, although a breach in the storage container can lead to explosive conditions or intense fires.
Dusts
Dusts also have upper and lower explosion limits, though the upper limits are hard to measure and of little practical importance. Lower flammability limits for many organic materials are in the range of 10–50 g/m³, which is much higher than the limits set for health reasons, as is the case for the LEL of many gases and vapours. Dust clouds of this concentration are hard to see through for more than a short distance, and normally only exist inside process equipment.
Flammability limits also depend on the particle size of the dust involved, and are not intrinsic properties of the material. In addition, a concentration above the LEL can be created suddenly from settled dust accumulations, so management by routine monitoring, as is done with gases and vapours, is of no value. The preferred method of managing combustible dust is by preventing accumulations of settled dust through process enclosure, ventilation, and surface cleaning. However, lower flammability limits may be relevant to plant design.
Volatile liquids
Situations caused by evaporation of flammable liquids into the air-filled void volume of a container may be limited by flexible container volume or by using an immiscible fluid to fill the void volume. Hydraulic tankers use displacement of water when filling a tank with petroleum.
Examples
The flammable/explosive limits of some gases and vapors are given below. Concentrations are given in percent by volume of air.
Class IA liquids with a flash point less than and boiling point less than have a NFPA 704 flammability rating of 4
Class IB liquids with a flash point less than and a boiling point equal to or greater than and class IC liquids with a flash point equal to or greater than , but less than have a NFPA 704 flammability rating of 3
Class II liquids with a flash point equal to or greater than , but less than and class IIIA liquids with a flash point equal to or greater than , but less than have a NFPA 704 flammability rating of 2
Class IIIB liquids with a flash point equal to or greater than have a NFPA 704 flammability rating of 1
ASTM E681
In the U.S. the most common method of measuring LFLs and UFLs is ASTM E681. This standard test is required for HAZMAT Class 2 Gases and for determining refrigerant flammability classifications. This standard uses visual observations of flame propagation in 5 or 12 L spherical glass vessels to measure the flammability limits. Flammable conditions are defined as those for which a flame propagates outside a 90° cone angle.
See also
Flammability
Limiting oxygen concentration
Minimum ignition energy
References
Further reading
David R. Lide, Editor-in-Chief; CRC Handbook of Chemistry and Physics, 72nd edition; CRC Press; Boca Raton, Florida; 1991;
Combustion
Explosion protection
Fire
Natural gas safety |
Introduction
Currently, renewable energies are receiving increasing attention every day. These energies are used to reduce gasoline and fuel consumption due to their burning every day. So the goal is to identify fuel mixtures with fewer effect for climate without losing its main properties to their purpose. It is necessary to investigate the optimization of the burning, which make progress a project and design the burners which need the information of the main flame characteristics, such as mixture flame propagation speed, laminar flame speed and flame surface density. An essential parameter in the laminar flame study is the determination of laminar flame speed (SL), which have been calculated using diverse methods, such as the use of a flat flame burner withal Bunsen burner [1][2][3][4], spherical flames [5] or just a Bunsen burner. Sadeghi et al. [6] studied experimentally the influence of equivalence ratio on methane premixed flame drive in the combustor. Their results showed that the flame location in the combustor is moved toward the reactor outlet by increasing the equivalence ratio toward the fuel rich side. [7] studied the influence of equivalence ratio differences on flame propagation and structure of methane-air laminar counterflow flames. They showed that the propagation velocity counts on the equivalence ratio rise through a flame. The investigation on the flame area density equation and its numerical explanation are listed in Prasad et al. [8] and Mohammed Kh. Abbas [9]. The crossed-planar tomography techniques are using by Bingham et al. [10] to determine the flame surface density from data of tomographic images. Moreover, the experimental study of flame area density is related to low turbulence intensities such as Deschamps et al. [11]. The influence of turbulence on the flame location was studied by a few of researchers. Hartung et al. [12] used circular duct combustor to recognize flame location from intensity of the hydroxide ion value. Moreover, the flame postion was studied by utilizing laser tomography technique [13]. Lean premixed flame in a gas turbine combustor was investigated by Yilmaz et al. [14]. They utilizd methane -air flames at different equivalence ratios values. Their results showed that flame length and thickness were decreases at increasing equivalence ratio. Thus concerning to the significance of the influence of flame moving on the function of the jet flow combustor, the main goal of this study is concentrate on the investigation of the significant factors on the function of premixed propane-air flames in the jet flow combustor. Therefore, in this paper, the influence of mixing ratio between propane and air (as equivalence ratio), turbulent intensity and flame area density on flame moving (as flame location) are investigation.
mathematical model
The equivalence ratio is the mass of fuel-to-oxidizer ratio to the stoichiometric mass fuel-to-oxidizer ratio and it is determined as follows.
=̇3 8⁄ (̇3 8⁄ )(1)
Where, the ̇3 8 and ̇ are a mass fraction of propane and air respectively, and subscript st denoted to stoichiometric condition. The combustion rate plays a vital role in the premixed turbulent flames. When the scale of turbulence is greater than the thickness of the flame, the turbulent flow wrinkles the laminar flame front and increases both the reaction rate and the flame surface area. The total combustion rate of the flame is evaluated by integration the local combustion rate over the flame surface. The flame surface density, ∑ is known as the mean flame-surface area per unit volume of the wrinkling flame caused by turbulence. The combustion rate of the reactants per unit volume (̇), can be described as [15,16].
̇= S L ∑( ) (2) where
is represent the density of the unburned gases, G is the flame stretch factor and ∑(x) is the local flame surface density. The formula of the flame surface density based on the progress variable of the flame can be described as [15,17,18,19].
∑( ) = 〈| | ( − )〉 (3)
where ∇c is the flame front gradient, ( − ) is the instantaneous flame front location. Figure 1 is depicted a jet flow combustor with 100 mm inner diameter and 550 mm length was used as an experimental reactor. Turbulence was generated by an active grid includ a sets of rotating wings by ten rods connected to ten motors. Test rig includ a set of piping and valves to transmitted and controlled fuel and air mixture. The mixture is mixed at various equivalence ratios, theninjected inside the combstion chamber to produce a premixed flame. The flame can be stabilized by flame holder. Also, includ high speed camera to capture images of premixed flame at environment conditions. The image has (576 x 720) pixels visualized to representing study on the characteristic of the flame location and topology. Each image is examined to debrief the flame area density. For each flame factor (equivalence ratio and Reynolds number), 174 -472 instantaneous flame images are recorded. The
Experimental details
Results and discussion
The contour of the numerical results of flame surface density ∑(x), at different equivalence ratios from lean Φ=0.6 to rich Φ=1.3 values is shown in Figure 2. The ∑(x) profile is maxima at the center of the burner and has a Mushroom shape. The flame location is confined in the combustion chamber domain in the area between the flame holder region and the end of jet burner pipe. The ∑(x) profiles have similar concave shapes symmetry about the central burner axis and do not change whatever equivalence ratio values; because of ∑(x) values are almost equipollent. This action was already revealed by F. Halter et al. [16]. This is related to turbulent length scale condition that remains fixed at variation of the equivalence ratio. The flame surface density ∑(x) profile as a function of the progress variable at different equivalence ratios is shown in Figure 3. The ∑(x) is increased until approximately the half of reactants is transform to products then decreased for both Φ=0.555 and 0.625. These results in good agreement trend with results obtained from Gulder and Samllwood [15].
The experimental results of this study are implemented in Figure 4, [3,20].
Conclusion
In this work, flame surface densities for premixed propane-air flames were studied numerically and experimentally at different equivalence ratios, Reynolds number and turbulent intensity. At different equivalence ratio range of up to 1.3, the flame surface density contour as a function of the progress variable was found to be insensitive to equivalence ratio variation. Moreover, the asymmetric stable flame may be formed inside the combustor domain.
Our results denote that the increase in flame surface density by diverse equivalence ratio may not be the controlling for flame speed propagation growing in turbulent combustion region especially when Φ is increasing from 0.555 to 0.625 and decreasing Reynolds number from 4660 to 2496. Furthermore, Flame surface density and the flame location was showed more sensitive by increasing turbulent intensity and moved the flame location toward the combustor jet pipe flow. Hence, this study is thought to be beneficial for those who work in turbulent combustion.
the instantaneous flame images is processed to get the flame contour which represented flame location inside the combustor domain to estimate flame surface density.Table 1presents the inlet flow conditions at different equivalence ratios used in this study.
Figure 1 .
1Schematic diagram of the experimental facility setup.
Figure 2 .
2Local flame surface density at different equivalence ratios.
The first row represented the instantaneous snapshots of flame front propagations in images, 1-5 and the main of 174 images in image 6 at Φ= 0.555 and Reynolds number equal to 4660. The flame location is confined in the area between the flame holder region and the end of jet pipe flow. Flame holder stabilizes the flame. The ten motors to rotate the active grid to generate turbulence are seems in these images. The second row represented the instantaneous snapshots in images, 1-5 and the main of 341 images in image 6 at Φ= 0.588 and Re= 4410. In these images, we focus on the flame region only. In the third row images which represented flame front propagations in images, 1-5 and the main of 472 images in image 6 at Φ= 0.606 and Re= 2571. In the last row which represented flame front propagations in images, 1-5 and the main of 316 images in image 6 at Φ= 0.625 and Re= 2496. Hence the flame is still confined between the flame holder region and the end of jet pipe flow region. Unfortunately, all tests were implemented in lean flame range. All experimental images are showing the same tendency of flame locations whatever equivalence ratio values. This scenario is a well-known phenomenon observed in combustion experiments of Halter et al.[16]. The influence of turbulent intensity on flame front propagation is display inFigure 5, which show the experimental results of the main of 341 locations at Φ= 0.588 and Re= 4410 at different turbulent intensity from weak to strong values. The flame front propagations are clear different by increasing The flame location is moved toward burner jet pipe flow by increasing turbulence subsequently, the flame surface density is increased. Strong turbulence influential usually results in flames that burn propagates faster and release higher heat.
Figure 3 .
3flame surface density profile as a function of progress variable at different equivalence fuel-air ratios.
Figure 4 .Figure 5 .
45Instantaneous snapshots(1)(2)(3)(4)(5), and the average (6) of the experimental flame propagation images at different equivalence ratios and Reynolds numbers. Mean of 341 instantaneous of experimental flame location at Φ=0.588, Re=4410 and(1)weak, (2) moderate and (3) strong turbulent intensity.
IOP Publishing doi:10.1088/1757-899X/1076/1/012077 Richardson et al.2
Table 1 .
1Inlet flow conditions at different equivalence ratios Equivalence ratio, ϕMass fraction
of fuel
Mass fraction
of Oxygen
Mass fraction
of Nitrogen
Inlet mean
velocity (m/s)
0.6
0.0389
0.2353
0.7258
0.1720
0.7
0.0451
0.2338
0.7211
0.1484
0.8
0.0512
0.2323
0.7165
0.1307
1
0.0632
0.2293
0.7075
0.1059
1.1
0.0691
0.2279
0.7030
0.0969
1.3
0.0806
0.2251
0.6943
0.0830
2nd International Scientific Conference of Engineering Sciences (ISCES 2020) IOP Conf. Series: Materials Science and Engineering
2nd International Scientific Conference of Engineering Sciences (ISCES 2020) IOP Conf. Series: Materials Science and Engineering
2nd International Scientific Conference of Engineering Sciences (ISCES 2020)
2nd International Scientific Conference of Engineering Sciences (ISCES 2020) IOP Conf. Series: Materials Science and Engineering
2nd International Scientific Conference of Engineering Sciences (ISCES 2020) IOP Conf. Series: Materials Science and Engineering
2nd International Scientific Conference of Engineering Sciences (ISCES 2020) IOP Conf. Series: Materials Science and Engineering
AcknowledgmentsThe experimental work was supported by University of Diyala, Iraq and Ozyegin University, Turkey.
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Abbas Alhumairi "Investigation of flame characteristics in a turbulent premixed combustion. Mohammed Kh, Istanbul, TurkeyOzygin UniversityPh.D thesisMohammed Kh. Abbas Alhumairi "Investigation of flame characteristics in a turbulent premixed combustion'' Ph.D thesis, Ozygin University, Istanbul, Turkey, 2018.
Crossed-plane laser tomography: Direct measurement of the flamelet surface normal. D Binghamf, Knaus Gouldind, doi.org/10.1016/S0082-0784(98)80392-5Symposium (International) on Combustion. 271BinghamF D,GouldinD and Knaus"Crossed-plane laser tomography: Direct measurement of the flamelet surface normal''Symposium (International) on Combustion,Volume 27, Issue 1, 1998, Pages 77-84, doi.org/10.1016/S0082-0784(98)80392-5.
Surface density measurements of turbulent premixed flames in a spark-ignition engine and a Bunsen type burner usingplanar laser-induced fluorescence. B Deschamps, G Smallwood, D Snelling, Ö Gülder, doi.org/10.1016/S0082-0784(96Symposium (International) on Combustion. 261Deschamps B,Smallwood G,Snelling D and Gülder Ö "Surface density measurements of turbulent premixed flames in a spark-ignition engine and a Bunsen type burner usingplanar laser-induced fluorescence"Symposium (International) on Combustion, Volume 26, Issue 1, 1996, Pages 427-435, doi.org/10.1016/S0082-0784(96)80245-1.
Effect of HeatRelease on Turbulence and Scalar-turbulence Interaction in Premixed Combustion. G Hartung, J Hult, C Kaminski, J Rogerson, N Swaminathan, Phys. Fluids. 20Hartung G, Hult J, Kaminski C, Rogerson J and Swaminathan N " Effect of HeatRelease on Turbulence and Scalar-turbulence Interaction in Premixed Combustion" Phys. Fluids, 20(2008), 3, pp. 1-17.
Heat Release Rate Markers for Premixed Combustion. Z Nikolaou, N Swaminathan, Combust. Flame. 16112Nikolaou Z and Swaminathan N " Heat Release Rate Markers for Premixed Combustion," Combust. Flame, Vol. 161, No. 12, pp. 3073-3084, 2014.
Numerical Study of Turbulent Lean Premixed Methane -Air Flames. B Yilmaz, S Özdoğan, I Gökalp, Fuels Combust. Eng. J. Yilmaz B, Özdoğan S and Gökalp I " Numerical Study of Turbulent Lean Premixed Methane - Air Flames" Fuels Combust. Eng. J., 2015, pp. 26-33.
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Zone conditional modeling of premixed turbulent flames at a high Damkohler number. Lee E Huh, K , Combust .Flame. 138211Lee E and Huh K "Zone conditional modeling of premixed turbulent flames at a high Damkohler number," Combust .Flame 138, 211 (2004).
Effects of strain rate and curvature on surface density function transport in turbulent premixed flames in the thin reaction zones regime. N Chakraborty, R Cant, Phys. Fluids. 1765108Chakraborty N and Cant R "Effects of strain rate and curvature on surface density function transport in turbulent premixed flames in the thin reaction zones regime," Phys. Fluids 17, 065108 (2005).
Flame behaviour and flame location in large-eddy simulation of the turbulent premixed combustion" First accepted paper. Mohammed Kh Abbas Alhumairi, A Yasseen, Almahdawi, A Sami, Nawi, J. Energy. Mohammed KH Abbas Alhumairi, Yasseen A Almahdawi and Sami A Nawi" Flame behaviour and flame location in large-eddy simulation of the turbulent premixed combustion" First accepted paper, J. Energy 2020.
Experimental and Computational Investigation of Flame Holders in Combustion Chambers at Different Thermal Loads. Mohammed Kh Abbas Alhumairi, S Yahya, Azzaw , J. of thermal Engineering. Paper In PressYildiz Technical UniversityMohammed KH Abbas Alhumairi, Yahya S, Azzaw Iand Al-rubaiy A. "Experimental and Computational Investigation of Flame Holders in Combustion Chambers at Different Thermal Loads" J. of thermal Engineering, Yildiz Technical University, Turkey. Paper In Press. March 2021.
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Introduction
Hydrogen-enrichment of natural gas (which mainly contains methane) will be used as a means to decarbonize several industries that use combustion equipment, such as land-based power generation gas turbine engines in the future [1]. While this is underway, our understanding related to the speed at which the fuel and air mixture is converted to combustion products (referred to as the turbulent burning velocity) at engine flowrelevant conditions is limited for both pure and hydrogen-enriched methane-air flames to our best of knowledge.
The burning velocity has been estimated using the flamelet assumption for methane-air flames, see for example the review papers by Driscoll [2,3]. This assumption suggests that the reaction zone of the premixed flames is relatively thin [2][3][4][5][6][7][8]. Although several studies show this assumption holds for a wide range of turbulence conditions [9,10], results of several other investigations [11][12][13][14][15][16][17][18][19][20][21] disagree and suggest the flamelet assumption may not hold. For these studies [11][12][13][14][15][16][17][18][19][20][21], the turbulent burning velocity cannot be estimated using the formulations developed based on the flamelet assumption. The present investigation is motivated by development and assessment of a formulation that allows for calculation of the burning velocity for turbulent premixed flames whose internal structure do not necessarily follow the prediction of the flamelet assumption for both pure and hydrogen-enriched methane-air turbulent premixed flames. In the following, first, literature related to the effect of the turbulent flow on the flame structure, as well as the implication of this effect on the burning velocity of methane-air premixed flames is briefly reviewed. Then, background related to the effect of hydrogen-enrichment on the methane-air premixed flames internal structure and burning velocity is presented.
Effect of turbulence on the flame internal structure and burning velocity
The internal structure of premixed flames can be highly influenced by the Karlovitz number, Ka = τ f /τ η K , where τ f and τ η K are the flame and Kolmogorov time scales, respectively [22,23]. Flames with Ka 1 usually feature both thin preheat and reaction zones, and the turbulent eddies only tend to wrinkle the flame surfaces [22,[24][25][26]. For Ka 1, the results reported in the literature for the preheat zone thickness are controversial. On one hand, as predicted by Peters [22], for 1 Ka 100, small eddies may penetrate into and broaden the preheat zone. This is confirmed through both experimental [9,11,12,[27][28][29][30][31] and Direct Numerical Simulation (DNS) studies [32,33]. However, several studies [9,25,[34][35][36] suggest that the preheat zone may not broaden for Ka 1. The reason for this discrepancy is elaborated in [3,9]. Driscoll et al. [3] and Skiba et al. [9] argue that, eddies associated with Ka 1 may feature sufficient turbulent kinetic energy allowing them to penetrate and broaden the preheat zone. Skiba et al. [9] and Driscoll et al. [3] suggested that, in addition to Ka 1, flames with u Λ/(S L,0 δ L ) 180 may feature broadened preheat zones, where Λ, S L,0 , and δ L are the integral length scale, unstretched laminar flame speed, and laminar flame thickness, respectively [3,9].
Similar to the preheat zone, the results reported in the literature regarding the turbulent flames reaction zone thickness are also controversial. Experimental [9] and DNS studies of [37][38][39] show that the reaction zone remains thin upto Ka ≈ 550 and 1000, respectively. In contrast to the studies of [9,[37][38][39], those of [11][12][13][14][15][16][17][18][19][20][21] suggest that the reaction zone is in fact broadened compared to the laminar flame counterpart. For example, in a recent investigation [11], the authors show that for flames with Ka ≈ 76, the reaction zone thickness can increase up to 3.9 times that of the corresponding laminar flame. Mohammadnejad et al. [11] speculated that relatively small size energetic eddies may penetrate into and broaden the reaction zone. It was shown [11] that the probability density function of eddy size distribution and kinetic energy of the eddies can be influenced by the type of the utilized turbulence generating mechanism, and this may be the reason for the discrepancy in the literature regarding the turbulent premixed flames reaction zone thickness.
The internal structure of turbulent premixed flames has implications for estimation of the turbulent burning velocity. This parameter can be estimated globally and locally, which are referred to as the global and local consumption speeds, respectively [2,3]. These speeds are estimated using [2,3,40] S T,GC =ṁ r ρ r A f (1a)
S T,LC = S L,0 I 0 L ξ ∞ −∞ ∞ −∞ Σ(η, ξ)dηdξ,(1b)
where S T,GC and S T,LC are referred to as the global and local consumption speeds, respectively [2].ṁ r and ρ r are the reactants mass flow rate and density. A f is the flame surface area estimated based on the mean progress variable (c). In Equation (1b), Σ is the flame surface density, L ξ is the length of the mean progress variable contour, I 0 is the Bray-Cant [41] stretch factor, and η and ξ are the curvilinear axes, which are respectively normal and tangent to a given c contour (usually c = 0.5). As reviewed in Driscoll et al. [2,3], there are two ongoing questions regarding the global and local consumption speeds of methane-air turbulent premixed flames in the literature. First, the DNS studies of [42][43][44] suggest that increasing the turbulence intensity increases the flame surface area such that the local consumption speed nearly equals the global consumption speed. However, several other studies, see for example [3,21,40,[45][46][47][48][49], suggest that as the turbulence intensity increases, the global consumption speed increases, but the flame surface area and the local consumption speed plateau. For instance, Wabel et al. [40] show that, at u /S L,0 ≈ 150, the global consumption speed is about 5 times the local consumption speed. Wabel et al. [40] speculated that, as the preheat zone broadens with increasing the turbulence intensity, the turbulent diffusivity of the gas in this zone increases, enhancing the transport of reactants and as a result increase of the global consumption speed. Recently, Mohammadnejad et al. [11] showed that, in addition to the preheat zone, the reaction zone also broadens with increasing the turbulence intensity, which may also contribute to the increase of the gas diffusivity. Both Gülder [46] and Nivarti et al. [45] performed theoretical calculations and showed that the enhancement of gas diffusivity inside the flame region can allow for elaborating the reason for the increase of the global consumption speed with increase of the turbulence intensity and as a result the difference between the local and global consumption speed values reported in for example [3,21,40,[45][46][47][48][49]. However, in both Gülder [46] and Nivarti et al. [45], the preheat and reaction zones thicknesses are not measured; and as a result, it is not known whether the enhancement of gas diffusivity is due to broadening of only the preheat zone or both the preheat and reaction zones. This requires further investigations.
The second question is related to the behavior of the global consumption speed itself. As hypothesized by Damköhler [50], also known as the first Damköhler's hypothesis, increasing u /S L,0 is expected to increase the global consumption speed linearly. Although, at relatively small turbulence intensities, the global consumption speed nearly follows a linear relation with the turbulence intensity [3,21,22,40,[49][50][51][52], at relatively intense turbulence conditions, the global consumption speed plotted against the turbulence intensity bends towards the axis of u /S L,0 . This is referred to as the bending behavior in the literature, see for example [21,26,40,49,52,53]. Several reasons such as nonlinear variation of gas diffusivity with turbulence intensity [3,45,50,51] as well as local quenching [3] are suggested to contribute to the bending behavior. To our best of knowledge, a potential relation between the flame quenching (or local extinction) and the bending behavior has not been studied yet.
Effect of hydrogen enrichment on turbulent premixed flame internal structure and burning velocity
The internal structure of hydrogen-enriched turbulent methane-air premixed flames has been recently investigated in Mohammadnejad et al. [8] and Zhang et al. [54]. The study of Mohammadnejad et al. [8] shows that, for relatively moderate turbulence conditions (u /S L,0 up to 2.6), the preheat and reaction zone thicknesses of the hydrogen-enriched flames are similar to the laminar premixed flame counterparts. Mohammadnejad et al. [8] showed that hydrogen enrichment (up to 50%) does not significantly influence the preheat and reaction zone thicknesses normalized by the corresponding laminar flame counterparts. Compared to [8], whose tested turbulence intensity was limited to 2.6, Zhang et al. [54] investigated both the reaction and preheat zone thicknesses for larger turbulence intensities (3 u /S L,0 12.5) with hydrogen-enrichment percentages examined up to 60%. They [54] showed that, similar to the methane-air turbulent premixed flames, increasing the turbulence intensity can lead to broadening of the hydrogen-enriched methane-air flames preheat zone. However, Zhang et al. [54] showed that the reaction zone thickness does not change by increasing the turbulence intensity.
Although studies of both [8,54] provide insight into the structure of hydrogen-enriched methane-air premixed flames at relatively small and moderate turbulence intensities, the preheat and reaction zone thicknesses of these flames pertaining to relatively intense turbulence conditions remain to be investigated.
Few experimental investigations [55,56] have studied the effect of hydrogen-enrichment on local and global consumption speeds of turbulent premixed flames. Both Halter et al. [56] and Guo et al. [55] showed that increasing the hydrogen-enrichment percentage increases the global consumption speed normalized by the unstretched laminar flame speed. Guo et al. [55] showed this parameter also increases with increasing the turbulence intensity. The values of the local consumption speed are not reported in [56], however, Guo et al. [55] showed that increasing both the hydrogen-enrichment percentage and the turbulence intensity increase the local consumption speed normalized by the unstretched laminar flame speed. Although these studies [55,56] elaborated the effect of hydrogen enrichment and turbulence intensity on the local/global consumption speeds, their investigations are performed for u /S L,0 5. To our best of knowledge, values of the local and global consumption speeds for hydrogen-enriched premixed flame are not investigated at larger turbulence intensities.
This study aims to address three objectives. The first objective of the present study is to measure the preheat and reaction zone thicknesses of hydrogen-enriched methane-air premixed flames pertaining to relatively intense turbulence conditions. To our best of knowledge, such information is not available in the literature. The second objective of this study is to develop a consumption speed estimation framework that does not rely on the flamelet assumption. Then, using this framework, we aim to understand the reason for the difference between local and global consumption speeds reported in the literature. The third objective of the present study is to characterize the bending behavior of the global consumption speed and to develop a mathematical formulation that allows to estimate the amount of bending.
Experimental methodology
The experimental setup, diagnostics, coordinate system, and the tested conditions are presented in this section.
Setup
The setup used in this study is a Bunsen burner identical to that utilized in [11,34]. This burner consists of an expansion section, a settling chamber (with 5 mesh screens), a contraction section, and a nozzle with exit di- generating mechanisms are used similar to [11]. Specifically, zero, one, or two perforated plates were utilized.
ameter
For the conditions with no perforated plate (which is the first turbulence generating mechanism), turbulence is primarily produced by the mesh screens and the Kelvin-Helmholtz instability that is developed in the jet shear layer, similar to [11,[57][58][59]. For the second turbulence generating mechanism, a perforated plate, with the technical drawing shown in Fig. 2(c), is placed 44.4 mm upstream of the nozzle exit plane. This plate contains 1.8 mm diameter circular holes arranged in a hexagonal pattern, generating a blockage ratio of 60%. For the third turbulence generating mechanism, one perforated plate (identical to that used for the second turbulence generating mechanism) is positioned 44.4 mm, and a second plate is located 30.4 mm upstream of the burner exit plane, see Fig. 2(b). The second perforated plate has holes positioned on a hexagonal arrangement with a diameter of 1.8 mm. The blockage ratio of this plate is 77%.
Diagnostics
Simultaneous Planar Laser-Induced Fluorescence (PLIF) of hydroxyl radical (OH) and formaldehyde molecule (CH 2 O) as well as separate Stereoscopic Particle Image Velocimetry (SPIV) were performed in this study. The diagnostics used here is similar to that used in Mohammadnejad et al. [11]. However, compared to [11], the SPIV experiments in the present study are performed only for the non-reacting flow conditions and to characterize the background turbulent flow. Both PLIF and SPIV data acquisition rate were 1 Hz. A dual-head Nd:YAG pump laser (Quanta Ray PIV400) and a frequency-doubled dye laser (Sirah Precision Scan) are used for generating the PLIF signals. Two laser pulses with wavelengths of 532 nm and 355 ± 3 nm are produced by and Coastal Optics UV lens and a Schott GG 395 longpass filter (for CH 2 O), are used to collect the PLIF signals. The projected spatial resolution of both cameras is 89 µm per pixel. The knife edge technique [71,72] was used to obtain the line spread functions of both cameras. It was calculated that the optical system effective resolution (the full width at half maximum of the line-spread function) is 263 µm. Two photodiodes, shown in Fig. 1, are utilized to collect pulse-to-pulse variations of the 282.94 nm and 355 nm beams energies, which are utilized for reduction of the PLIF data discussed in the next section. Further details regarding the utilized PLIF system can be found in [8,11].
The SPIV system contains a dual-cavity, double-pulse, Nd:YAG laser (BSL Twins CFR PIV200) as well as C 3 and C 4 sCMOS cameras (LaVision Imager sCMOS), which are equipped with Scheimpflug adapters and Tokina lenses, see Fig. 1. The laser generates pairs of 532 nm beams with a 4-33 µs separation time PLIF and SPIV images are registered and mapped to one physical coordinate system using a three-dimensional LaVision Type 20 target plate. LaVision DaVis 8.4 software is used to calculate the velocity vectors. The details of the PIV vector calculation is identical to that described in [11]. which is similar to [11].
Coordinate system
Tested conditions
In total, 68 experimental conditions are tested, with the corresponding details tabulated in Table 1 Cantera simulations [73] with the GRI-Mech 3.0 mechanism are used to estimate the unstretched laminar flame speeds (S L,0 ). Laminar flame thickness is calculated using δ L = (λ/c p )/(ρ 0 S L,0 ), with λ and c p being the gas thermal conductivity and specific heat (both estimated at 1500 K), and ρ 0 being the fuel and air mixture density (estimated at 300 K), similar to [3,9,11,22].
Root Mean Square (RMS) of the velocity fluctuations along the y (u ), x (v ), and z (w ) directions as well as the integral (Λ), Taylor (l T = Λ(u Λ/ν) −1/2 ), and Kolmogorov (η
K = (ν 3 / ) 1/4 = Λ(u Λ/ν) −3/4 ) length
scales are averaged within the red dotted-dashed window of Fig. 3, and the results are presented in the table.
In the equations used for calculation of the Taylor and Kolmogorov length scales, ν is the fuel and air mixture kinematic viscosity (estimated at 300 K) and = u 3 /Λ [3,74]. The integral length scale, Λ, is estimated using the formulations provided in [74] and the procedures discussed in [8,11]. Similar to [11], conditions pertaining to the first turbulence generating mechanism feature the Kelvin-Helmholtz instability. This instability is generated by the jet shear layer, can influence the values of the RMS velocity and integral length scale, and does not correspond to the background turbulent flow. Thus, using the Proper Orthogonal Decomposition technique [75] and similar to [11], the Kelvin-Helmholtz modes are identified and excluded from the non-reacting flow data pertaining to zero perforated plates, following the procedures discussed in [11]. The Reynolds (Re T ) and Karlovitz (Ka) numbers are estimated using Table 1. The effective Lewis number (L eff ) of the fuel and air mixture was estimated using the formulations provided in Mohammadnejad et al. [8], with the corresponding values presented in the last column of the table.
Re T = u Λ/ν and Ka = (u /S L,0 ) 3/2 (Λ/δ L ) −1/2 , with the values provided in
All test conditions are overlaid on the Borghi-Peters [22,76] diagram, as shown in Fig
Data reduction
For each test condition, 500 pairs of OH and CH 2 O PLIF images were collected simultaneously. The PLIF data is used to study both the internal structure as well the burning rate of the tested flames. The processes re- Table 1. Tested experimental conditions. For all conditions, φ = 0.7. U , SL,0, u , v , and w are in m/s and δL, ηK, lT and Λ are in mm. In order to correct the PLIF images for the effect of the background noise, separate 500 pairs of images were collected for each test condition using the PLIF cameras while the lasers were turned off. These images are averaged and subtracted from the corresponding OH and CH 2 O PLIF data. Then, the obtained images are normalized by the corresponding laser profiles. The profile of the 283 nm laser sheet is obtained from separate acetone PLIF experiments. For these, the ICCD camera C 1 (in Fig. 1) was equipped with a 305 nm longpass filter. Then, 500 acetone PLIF images were collected, averaged, and used as the laser profile correction of the OH PLIF images. The 355 nm laser sheet profile, which is used to normalized the CH 2 O PLIF images, is acquired similarly except that the longpass filter was removed from the camera and Rayleigh scattering images were collected and used instead, which is similar to our previous study [11]. As discussed in Section 2, two photodiodes were used to capture the laser pulse energy variations of both 283 and 355 nm beams. These are Similar results are obtained using the Wiener [79] and Gaussian [80,81] filters. Care was taken to ensure the utilized filters do not influence the results. Finally, a global threshold is applied to the images. The application of the median based filters and the global threshold is denoted by process (2) in Fig. 5. The results in Fig. 5(e) and (f) demonstrate the final representative OH and CH 2 O PLIF images after applying both processes (1) and (2).
U H 2 % S L,0 δ L u v w η K l T Λ u /U u /S L,0 Λ/δ L Re T Ka
After generating the reduced OH and CH 2 O PLIF images, the local, normalized, and relative heat release rate (HRR) was obtained, using the model presented in [8]. This model suggests that the heat release rate is proportional to (CH 2 O PLIF ) α × (OH PLIF ) β , with α and β depending on the tested fuel-air equivalence ratio and the hydrogen-enrichment percentage [8]. In the study of [8], α and β are reported for H 2 % upto 50%.
Since, in the present study, tests at H 2 % = 60 and 70% are also performed, and the corresponding values of α and β are not available in [8], these parameters are calculated following the procedure discussed in [8] and the results are tabulated in Table 2 The PLIF data was used to estimate the preheat and reaction zones thicknesses. Similar to [9,11,82,83], pixels that feature I HRR values larger than 50% of the global maximum highlight the reaction zone. The leading edge of the preheat zone is where CH 2 O PLIF signal equals 35% of the maximum CH 2 O PLIF signal [77,83]. The trailing edge of the preheat zone is the leading edge of the reaction zone. The preheat and reaction zones for the representative frames presented in Fig. 5 are shown by the cyan and red colors in Fig. 5(h), respectively. After removing the regions pertaining to the reaction zones, the combustion products are defined as the regions where OH PLIF signal is larger than 15% of the global maximum. The combustion products are shown by the yellow color in Fig. 5(h). The above procedure for obtaining the preheat, reaction, and combustion products zones are identical to that used in [11]. As discussed in [11], five parameters may potentially lead to the uncertainty in estimation of the preheat and reaction zone thicknesses. These parameters are the filtering process, three-dimensional orientation of the flames, imaging resolution, optical blur, and laser sheet thickness.
Influence of filtering was discussed earlier. Effect of three-dimensional orientation of the flame is studied in past investigations [24,80,[85][86][87][88][89][90][91]. For example, study of Rosell et al. [80] shows that for a flame with Ka = 60, the estimated preheat and reaction zone thicknesses can be influenced by three-dimensionality of the flames up to 8% and 11%, respectively. Since this Karlovitz number is close to the maximum tested Ka of the present study (which is Ka = 76), the effect of three-dimensionality on the reported results is not expected to be significant. The effects of imaging resolution, optical blur, and laser sheet thickness on the reported preheat and reaction zone thicknesses have been investigated and reported in our previous study [11] using the results, guidelines, and procedures presented in [42,92]. As discussed in [11], such effects are also not expected to influence the preheat and reaction zone thicknesses reported in the present study.
Results
The results are grouped into two subsections. In the first subsection, the preheat and reaction zone thicknesses of the hydrogen-enriched methane-air turbulent premixed flames are presented and discussed. Then, in the second subsection, the turbulent premixed flames burning rate is investigated. as the Karlovitz number increases to large values, the preheat and reaction zones broaden significantly. This observation is consistent with the results presented in [11][12][13][14][15][16][17][18][19][20][21].
Preheat and reaction zones thicknesses
Following the procedure elaborated in [11] and discussed in Section 3, the thicknesses of both preheat and reaction zones were estimated for each frame of the tested conditions. The averaged preheat (δ P ) and Table 3 and correspond to test conditions with no turbulence generator and at the smallest tested mean bulk flow velocity (5 m/s). The condition associated with the largest tested turbulence intensity (that is U35H00T2) features the maximum uncertainty for estimation of the preheat and reaction zone thicknesses. In order to estimate the maximum uncertainty associated with δ P and δ F , the test condition of U35H00T2 was repeated three times, the maximum deviation from the mean value was Wang et al. [21], and Mohammadnejad et al. [11], which are shown by the dark red dotted-dashed, blue dotted, and black dashed curves respectively. The studies of [9,11,21] correspond to pure methane-air flames. Unlike the present study that the fuel-air equivalence ratio is fixed and equals 0.7, results of [9] pertain to the fuel-air turbulent premixed flames has been recently reported in the study of Zhang et al. [54]. However, the tested conditions in [54] correspond to to a maximum turbulence intensity of about 12.5. The results of the present study suggest this broadening extends to u /S L,0 ≈ 42 (for 10% hydrogen-enrichment).
Driscoll et al. [3] and Skiba et al. [9] suggest the turbulent premixed methane-air flames with u Λ/(S L,0 δ L ) 180 may feature preheat zone broadening. Variation of the normalized preheat zone thickness versus u Λ/(S L,0 δ L )
is presented in Fig. 8 for all tested conditions. As can be seen, test conditions with u Λ/(S L,0 δ L ) 180 feature δ P /δ P,L 1.5, however, those with u Λ/(S L,0 δ L ) 180 feature δ P /δ P,L 1.5. For pure methane-air turbulent premixed flames, our results agree with those of [3,9]. The results presented in Fig. 8 suggest that the border of u Λ/(S L,0 δ L ) ≈ 180 can also be used for predicting the preheat zone broadening of hydrogenenriched methane-air turbulent premixed flames.
The normalized reaction zone thickness reported in the studies of Skiba et al. [9], Zhou et al. [12], and Mohammadnejad et al. [11] are overlaid on Fig. 7(d), which are shown by the dark red dotted-dashed, blue dotted, and black dashed lines respectively. Results of the present study show that increasing the turbulence intensity increases the normalized reaction zone thickness as shown in Fig. 7(d). This increasing trend is similar for all tested hydrogen-enrichment percentages and agrees well with the results of both Zhou et al. [12] and
Mohammadnejad et al. [11]. Compared to the results of the present study and those of [11,12], Skiba et al. [9] suggest that the reaction zone thickness remains nearly constant and does not vary by increasing the turbulence intensity. For pure methane-air turbulent premixed flames, Mohammadnejad et al. [11] experimentally showed that the reason for the broadening of the preheat zone is due to penetration of turbulent eddies into this zone.
Also, Mohammadnejad et al. [11] showed that the probability density function of the turbulent eddy size is significantly influenced by the utilized turbulence generating mechanism. As a result, they [11] speculated the reason for the controversial observation reported for the reaction zone thickness in their study and in [12] compared to that in [9] is due to the difference between the utilized turbulence generating mechanisms. Nevertheless, the broadening of the reaction zone for hydrogen-enriched methane-air flames shown in Fig. 7(b and d) at relatively large turbulence intensities is reported in the present study for the first time to the best knowledge of the authors. In essence, the results presented in Fig. 7 show that both the preheat and reaction zones of the pure and hydrogen-enriched methane-air turbulent premixed flames can feature broadening. For example, the preheat and reaction zone thicknesses can feature values that are respectively 6.3 and 4.9 times those of the laminar flame counterparts as shown by the probability density functions in Figs. 7(a and b).
Turbulent premixed flame burning rate
The local consumption speed normalized by the unstretched laminar flame speed is estimated from Eq. (1b) and the results are presented in Fig. 9(a) for all tested conditions. Please note that in Eq. (1b), the stretch factor (I 0 ) is assumed to be unity, similar to [40], as the effective Lewis number is close to unity for the tested conditions (please see the last column of Table 1). The maximum uncertainty in estimation of the local consumption speed is related to test condition of U35H00T2, and is shown by the error bar in Fig. 9(a). The procedure for estimation of the error bar is similar to that discussed in Section 5.1. The results in Fig. 9(a) are also color coded based on the integral length scale of the test conditions and presented in Fig. 9(b). Overlaid on both Figs. 9(a) and (b) are the results extracted from Wabel et al. [40] and Wang et al. [21], which are shown by the red dotted-dashed and blue dotted lines, respectively. The integral length scale in the study of Wabel et al. [40] varies between 6.1 and 41 mm and that in Wang et al. [21] is 2.9 mm. As can be seen, variation of S T,LC /S L,0 is significantly dependent on the integral length scale and follows two trends. For Λ 4 mm, our results suggest that the normalized local consumption speed plateaus at about 2 following [21]; and, for Λ 4 mm, S T,LC /S L,0 plateaus at about 5 following [9]. Plateau of the normalized local consumption speed with increase of the turbulence intensity (evident in Fig. 9) has been a matter of discussions in the literature.
Several investigations [3,21,40,45] suggested the reason for this plateau is saturation of the flame surface area with increase of u /S L,0 at large values of this parameter. However, the results presented in Fig. 7 as well as those in [11][12][13][14][15][16][17][18][19][20][21] suggest that increasing the turbulence intensity broadens both the preheat and reaction zones, and as a result, the flamelet assumption may not hold for such conditions. This means that Eq. (1b), which is developed based on the flamelet assumption, may lead to inaccurate estimation of the local consumption speed.
Instead, here, we propose a new formulation that does not rely on the flamelet assumption, which is discussed in the following.
In order to develop a formulation that does not take into account the flamelet assumption, first, similar to [21,40,93,94], the OH PLIF images are binarized and the mean progress variable field (c OH ) is obtained by averaging the binarized images. Please note this binarization is only performed to calculate the mean progress variable fields, is conducted for flames that are reported to be both relatively thin [40] and thick [21], and does not necessarily imply a presumed structure for the reaction zone. Then, a curvilinear coordinate system (ξ − η), with ξ and η being respectively tangent and normal to c OH contours are constructed. The time-average heat release rate is integrated along η−axis, which is locally normal to the mean progress variable contours of c OH = 0.5. This integral depends on ξ and is given by
B T,ξ (ξ) = ηmax η min HRR T (η, ξ)dη,(2)
where HRR T (η, ξ) is the mean heat release rate of turbulent flames estimated locally.
B L = 1 L ξ,L ξmax ξ min ηmax η min HRR L (η, ξ)dηdξ,(4)
where HRR L (η, ξ) and L ξ,L are the mean laminar flame heat release rate estimated locally and the laminar flame length estimated using the length of c OH = 0.5. Dividing Eq. (3) by Eq. (4) leads to
B T B L = L ξ,L L ξ,T ξmax ξ min ηmax η min HRR T (η, ξ)dηdξ ξmax ξ min ηmax η min HRR L (η, ξ)dηdξ .(5)
It is assumed that the heat release rate is proportional to I HRR estimated using the OH and CH 2 O PLIF signals following the procedures provided in Section 3. Using this assumption, Eq. (5) can be simplified to
B T B L = L ξ,L L ξ,T ξmax ξ min ηmax η min I HRR,T (η, ξ)dηdξ ξmax ξ min ηmax η min I HRR,L (η, ξ)dηdξ(6)
where I HRR,T and I HRR,L are the mean I HRR corresponding to turbulent and laminar flames, respectively.
Equation (6) allows for estimation of the turbulent flame burning rate normalized by that for the laminar counterpart and is independent of the internal flame structure. In fact, in the following, it is shown that for flames whose internal structure follows the flamelet assumption, Eq. (6) leads to values of burning rate that are similar to those obtained utilizing the formulation proposed by Driscoll [2], i.e. Eq. (1b).
Variation of B T /B L , estimated from Eq. (6), versus u /S L,0 is presented in Fig. 10 In order to highlight this, the data presented in Fig. 10(a) is color coded based on the tested integral length scale and presented in Fig. 10(b). As evident in the figure, for Λ 4 mm, the values of B T /B L are close to the normalized global consumption speed pertaining to the study of Wang et al. [21];
however, for Λ 4 mm, the results are closer to those of Wabel et al. [40]. Comparison of the results presented in Fig. 10 with those in Fig. 9 suggests that the values of B T /B L and S T,GC /S L,0 are similar, and they are both significantly larger than those of S T,LC /S L,0 .
In order to study the reason for the disparity between the values of the normalized burning rate and the normalized local consumption speed, the following parameter is defined.
J = B T /B L S T,LC /S L,0 .(7)
Variation of J versus u /S L,0 for the present study is shown in Fig. 11 by the open black circular data symbol.
As can be seen, the values of J are larger than unity, and this parameter increases with increasing u /S L,0 .
Variation of the normalized global consumption speed divided by the normalized local consumption speed (i.e.
S T,GC /S T,LC ) is extracted from the studies of Wabel et al. [40] and Wang et al. [21], and their results are presented in Fig. 11 by the solid dark red and blue triangular data symbols, respectively. Agreeing, with our results, those of past investigations [21,40] also suggest that the local consumption speed underpredicts the turbulent premixed flames burning velocity.
The potential underlying reason for the underprediction of the burning velocity by the local consumption speed has been a matter of discussion over the past decades, see for example [3]. Gülder [46] and Nivarti et al. [45] suggested that the reason for the observed difference between the local and global consumption speed values can be explained by taking into account the enhanced diffusivity of the reactants due to penetration of small scale eddies into the flame region. Using the mathematical formulations proposed by Nivarti et al [45] and Gülder [46] as well as the non-dimensional numbers related to test conditions of the present study (Ka, u /S L,0 , and Re λ = u l T /ν), the ratio of the global to local consumption speed was estimated and the results are presented in the Fig. 11 by the green dot-and-circle as well as pink double circle data symbols, respectively.
As can be seen, the ratio of the burning rate to local consumption speed in this study (J, the black circular data points) is close to that observed in the literature [21,40] for the ratio of the global to local consumption speeds (S T,GC /S T,LC ). Also, the results estimated based on the mathematical formulation proposed in Nivarti et al. [45] for S T,GC /S T,LC agrees well with J obtained from the present study. However, values of the global consumption speed divided by the local consumption speed obtained based on the Gülder's formulation [46] deviates from those of the present study and other experimental results [21,40] at large turbulence intensities.
The reason for the deviation of the results of the present study and the prediction from the formulation provided by Gülder [46] is speculated to be possibly linked to the assumptions made for derivation of the formulation in [46]. Specifically, Gülder [46] assumed that the enhanced diffusivity occurs only at the Taylor length scale, while Nivarti et al. [45] considered enhancement of diffusivity at all length scales smaller than the laminar flame thickness.
The underlying reason for the increasing trend pertaining to variations of J and S T,GC /S T,LC with u /S L,0 is hypothesized to be linked to the internal structure of the tested flames. In order to investigate this hypothesis, variations of J verses the preheat and reaction zone thicknesses are shown in Figs. 12(a) and (b), respectively.
As can be seen, δ P /δ P,L and δ F /δ F,L are positively correlated with J. Such correlation is even more pronounced for the reaction zone thickness and follows a linear trend. Thus, a line was fit to the data in Fig. 12(b) using the least-square technique. The equation of the line is give by
J = 1.9(δ F /δ F,L ) − 0.9.(8)
Equation (8) suggests that, at the limit of δ F = δ F,L , where the flamelet assumption holds, the normalized burning rate estimated from Eq. (6) equals the normalized consumption speed estimated from Eq. (1b). However, increasing the reaction zone thickness leads to larger values of the normalized burning rate compared to the normalized local consumption speed. This means that thickening of the turbulent premixed flames is linked to the deviation of the normalized burning rate (and the normalized global consumption speed) from the corresponding normalized local consumption speed values. In fact, the reason for this deviation being linked to the internal flame structure was speculated by Wabel et al. [40] earlier. However, compared to Wabel et al. [40] who suggested the reason for the deviation between S T,GC and S T,LC may be due to the broadening of the preheat zone, our results show such deviation is linked to broadening of both the preheat and reaction zones. It is experimentally shown that [11,95], with increasing the turbulence intensity, the eddies can penetrate into the preheat zone. This is expected to increase the gas turbulent diffusivity, which increases the burning rate [3,45,46,50], and as a result, the larger than unity values of J presented in Fig. 12(a). It is speculated that, similar to the preheat zone, the turbulent eddies may also penetrate into the reaction zone, leading to increase of δ F (as evident in Fig. 7(b) as well as the results presented in [11,12,21]), increasing the turbulent diffusivity, and as a result increasing the flame burning rate. However, the above speculation (that is penetration of turbulent eddies into the reaction zone) remains to be investigated experimentally. It is proposed that Eqs. (7) and (8) can be combined with Eq. (1b) in order to modify the formulation of the local consumption speed suggested by Driscoll et al. [2] accounting for the reaction zone thickening. This equation is given by
B T B L = J [1.9(δ F /δ F,L ) − 0.9] I 0 ∞ −∞ ∞ −∞ Σ(η, ξ)dηdξ L ξ .(9)
The values of the normalized burning rate estimated from Eq. (6) along with the prediction of Eq. (9) are presented by circular and square data symbols in Fig. 13 for all test conditions. The results in this figure suggest that the local consumption speed corrected for the effect of flame thickening (Eq. (9)) follows the values of the burning rate estimated from Eq. (6). This means that the reason for the deviation between the global (here burning rate) and local consumption speeds is the thickening of the reaction zone. This is not shown in the past investigations to our best of knowledge and is demonstrated here.
Although the above argument suggests the values of normalized burning rate can be reconciled using the reaction zone thickness and the integral of the flame surface density, the reason why the variation of B T /B L versus u /S L,0 bends toward the horizontal axis with increasing the turbulence intensity, see Fig. 10, is unclear in the literature, has been a matter of discussions [3], and is investigated here. This behavior is referred to as the bending behavior and is reported in past investigations, see for example [21,26,40,49,52,53]. Here, first, the bending behavior is characterized by estimating the difference between the values of the normalized burning rate and the prediction of the Damköhler's first hypothesis [50] (shown by the dashed line in Fig. 10). This difference is referred to as D and is estimated by
D = 1 + u S L,0 − B T B L .(10)
For example, at u /S L,0 = 19.4 and H 2 % = 50%, D is about 4.6, which is shown by the double-sided arrow in Fig. 10(a). D was estimated for all tested conditions in Table 1, and the results are presented in Fig. 14(a).
Also overlaid on the figure is the difference between the values of the normalized global consumption speed pertaining to the studies of [21,40] from the dashed line in Fig. 10(a). The estimated values of D are also color coded based on the integral length scale of the tested conditions and shown in Fig. 14(b). As can be seen, D is nearly zero for test conditions corresponding to small turbulence intensities, but it increases with increasing u /S L,0 . Also, the results in Fig. 14(b) show that, at a given turbulence intensity, D nearly decreases with increasing the integral length scale.
The underlying reason for the above observations is hypothesized to be linked to pronounced occurrence of local extinctions and incomplete combustion at relatively intense turbulence conditions. The hydroxyl radical is a post flame species and its concentration is expected to be positively related to completion of the combustion process [22,96]. Thus, it is expected that generation of OH radical should be inversely related to incomplete combustion as well as the occurrence of local extinction events. In fact, occurrence of local extinctions has been investigated using the OH PLIF signal in the past, see for example the studies of [97][98][99][100][101]. In the present study, the number of pixels that feature relatively large values of OH PLIF signal (more than 15% of the maximum)
were obtained and averaged for all acquired frames of a given test condition, which is referred to as N OH .
In order to facilitate comparison between different test conditions, N OH was normalized by the number of pixels that are expected to feature relatively large time-averaged OH PLIF signal, which is referred to as N OH .
Variations of (N OH /N OH ) −1 versus D as well as u /S L,0 are presented in Fig. 15(a), and (b), respectively.
The maximum uncertainty for estimation of (N OH /N OH ) −1 corresponds to the test condition of U35H00T2, is estimated using the procedure discussed in Section 5.1, and is shown by the error bar in Fig. 15(a). The results in the figure show that (N OH /N OH ) −1 is highly correlated with D. This correlation suggests that the occurrence of local extinctions and incomplete combustion are related to the observed bending behavior.
The results presented in Fig. 15(b) suggest that increasing the turbulence intensity increases (N OH /N OH ) −1 . obtained that
D ≈ 3.1 ( u S L,0 )( Λ δ L ) −1 2 + 3.5 ( u S L,0 )( Λ δ L ) −1 .(11)
Combining Eqs. (10) and (11), it can be shown that the normalized burning rate is obtained from
B T B L ≈ 1 + u S L,0 Term I −3.1 ( u S L,0 )( Λ δ L ) −1 2 − 3.5 ( u S L,0 )( Λ δ L ) −1 Term II .(12)
In Eq. [50] is also shown by the black dashed line.
The results in Fig. 17 suggest that the formulation proposed in Eq. (12) allows for prediction of the normalized burning rate. The results also show that, flames with larger Λ/δ L feature less pronounced bending behavior;
and, at a fixed value of u /S L,0 , increasing Λ/δ L increases the normalized burning rate. In fact, at the limit of Λ/δ L approaching infinity, Eq. (12) predicts that B T /B L approaches the prediction of the Damköhler's first hypothesis shown by the dashed line in Fig. 17. Also, for a fixed value of Λ/δ L , the variation of the normalized presented in Fig. 17 is that the burning rate cannot increase indefinitely with increasing the turbulence intensity.
However, at very large normalized integral length scales, the amount of bending is less pronounced. This conclusion is of relevance to DNS studies. Compared to experimental investigations, the DNS studies tend to utilize a relatively small domain of investigation and as a result a relatively small integral length scale, see for example studies of [32,33,43,44]. Our results suggest, increasing the size of the domain of investigation and the integral length scale could potentially allow for the DNS investigations to capture relatively larger values of the burning rate.
Conclusions
The internal structure and burning rate of extremely turbulent hydrogen-enriched methane-air premixed flames were investigated using simultaneous planar laser-induced fluorescence of OH and CH 2 O as well as separate stereoscopic particle image velocimetry techniques. In total, 68 test conditions were examined. Fuelair equivalence ratio was set to 0.7 for all tested conditions, and hydrogen-enrichment percentage was varied from 0% to 70% with steps of 10%. Four mean bulk flow velocities of 5, 15, 25, and 35 m/s were examined.
Three turbulence generating mechanisms corresponding to none, one, or two perforated plates were utilized.
The turbulence intensity (u /S L,0 ) of the tested conditions varied from 0.3 to 44.6, leading to Reynolds and Karlovitz numbers ranging from 18 to 2729 and 0.1 to 76.0, respectively.
Preheat and reaction zones of hydrogen-enriched methane-air turbulent premixed flames were estimated. It was shown that, at large turbulence intensities, both preheat and reaction zones feature broadening, and their thickness can increase up to 6.3 and 4.9 times those of the laminar flame counterparts, respectively. While broadening of the preheat zone at large turbulence intensities has been reported in the literature for methane-air flames, broadening of this zone for hydrogen-enriched extremely turbulent premixed flames is reported in this study for the first time to the best knowledge of the authors. Similar to extremely turbulent pure methane-air flames, our results show that turbulent premixed hydrogen-enriched methane-air flames also feature broadening of the reaction zone, which is shown here for the first time to our best of knowledge.
Broadening of the reaction zone observed for both pure and hydrogen-enriched methane-air flames suggests that the flamelet assumption may not lead to an accurate estimation of the burning rate for these flames. A framework that does not utilize the flamelet assumption was developed here and was used to estimated the tested flames burning rate. Also, the values of the local consumption speed were estimated for all tested conditions.
The results show that, at relatively small values of the turbulence intensity, the burning rate follows the local consumption speed. However, at larger turbulence intensities, the burning rate follows the global consumption speed reported in the literature. Similar to past investigations, our results show that increasing the turbulence intensity increases the difference between the estimated values of the burning rate and the local consumption speed. Such disparity has been a matter of discussion in the literature. Our results show that the ratio of the normalized burning rate and the normalized local consumption speed is positively correlated with both preheat and reaction zone thicknesses, with the latter correlation being more pronounced. This implies that the flamelet assumption used for calculation of the local consumption speed may have caused the reason for the deviation between the values of global and local consumption speeds reported in the literature. It is shown that, correcting the formulation of the local consumption speed by a non-dimensional factor that takes into account the reaction zone thickening, the burning rate of the tested flames can be reconciled.
Similar to past investigations related to the global consumption speed, the results show that increasing the turbulence intensity does not linearly increase the burning rate, and this parameter features a bending behavior.
First, the amount of bending in variation of the normalized burning rate versus the turbulence intensity was quantified. It was hypothesized and shown that the amount of bending is positively related to the occurrence of local extinctions. The results show that both the amount of bending and the occurrence of local extinctions are positively (negatively) related to the turbulence intensity (normalized integral length scale). Using this, a formulation that allows for quantifying the bending behavior was developed. The prediction of the formulation was compared with the experimentally estimated value of the burning rate, and it was shown that both agree well. The proposed formulation suggests that, at a given turbulence intensity, increasing the normalized integral length scale increases the normalized burning rate approaching a limiting value predicted by Damköhler's first hypothesis. At a fixed value of the integral length scale, increasing the turbulence intensity, first, increases the burning rate. However, the proposed formulation (in agreement with past experimental results) predicts that further increasing the turbulence intensity decreases the burning rate, which is due to pronounced occurrence of local extinctions.
Fig. 1 .
1Schematic of the experimental setup and the diagnostics.
Fig. 2 .
2Technical drawing of (a) the burner nozzle as well as (b and c) the perforated plates. the pump laser using harmonic generators. As shown inFig. 1, the 532 nm beam is used to pump the dye laser to generate a 283 nm (282.94 ± 0.005 nm) beam. This beam is used to excite Q 1 (6) line of the OH A-X system(1,0) vibrational band [8, 11, 60-67]. The 355 nm beam is used to excite theà 1 A 2 −X 1 A 1 4 1 0 vibronic manifold of CH 2 O similar to [8, 11, 60, 62-64, 67-70]. Using mirrors (M 1 − M 3 ) and cylindrical lenses (L 1 − L 3 ) shown in Fig. 1, the 282.94 nm and 355 nm beams are converted to coincident laser sheets with the thickness and height of about 250 µm and 40 mm, respectively. Two PIMAX ICCD cameras (see, C 1 and C 2 in Fig. 1), each equipped with a Nikkor UV lens and a bandpass filter with center wavelength of 320 ± 20 nm (for OH)
Fig. 3 .
3The coordinate system, field of view, and flow characterization region (FCR). The dimensions are in mm.(depending on the tested mean bulk flow velocity). M 1 − M 3 mirrors as well as L 1 − L 3 cylindrical lenses (seeFig. 1) are utilized to convert the PIV laser beams to laser sheets that are coincident with those of the PLIF lasers. The field of view and projected spatial resolution of the SPIV cameras are 84 mm×70 mm and 29.3 µm/pixel, respectively. Olive oil is atomized using a TSI Six-Jet atomizer and is fed into the burner.
A
Cartesian coordinate system, presented in Fig. 3, is used in the present study. The origin of the coordinate system is at the intersection of the burner centerline and the nozzle exit plane. The x− and y−axes are at the imaging plane and lie inside the laser sheets. The z−axis is normal to the x − y plane. The PLIF and SPIV field of views, shown by a green dashed window in Fig. 3, are coincident. In the figure, the flow characterization region (FCR) highlights the location at which the non-reacting turbulent flow characteristics are averaged,
. 4 .
4The results in the figure suggest that flames with U = 5 m/s and no perforated plate pertain to the wrinkled flames regime. Flames with U = 5 m/s and one perforated plate as well as Flame U15H70T1 pertain to the corrugated flames regime. The rest of the tested conditions are positioned in the thin reaction zones regime. In Fig. 4, the newly-suggested border of u Λ/(S L,0 δ L ) = 180 [3, 9], which separates the flames with thin and broadened preheat zones, is also presented. This border suggests that the conditions pertaining to U = 15, 25, and 35 m/s with 2 perforated plates as well as Flame U35H00T0 are expected to feature a broadened preheat zone. Flames U25H00T0, U25H40T0, and U35H40T0 are positioned near the border of u Λ/(S L,0 δ L ) = 180. The rest of the tested conditions are expected to feature a relatively thin preheat zone. The predictions of the Borghi-Peters diagram related to thin and broadened preheat zones are discussed in detail later in the results section.
Fig. 4 .
4The tested experimental conditions overlaid on the Borghi-Peters diagram[22]. lated to reducing the raw PLIF images is discussed in this section.Figures 5(a) and (b)show two representative frames of the raw OH and CH 2 O PLIF images, respectively. These frames are related to condition U5H40T1.
used to normalize both the OH and CH 2 O PLIF images (after laser profile correction) in order to remove the effect of the shot-to-shot variation of the lasers pulse energies.Figures 5(c) and (d) show the representative frames of OH and CH 2 O PLIF images corrected for the effects of background noise, laser profile, and shot-toshot laser energy variations. These corrections are shown as process (1) in Fig. 5. After applying the corrections related to process(1), in order to decrease the remaining background noise, similar to[8,9,11,12,29,77,78], 7 × 7 and 11 × 11 pixels 2 median-based filters are applied to the OH and CH 2 O PLIF images, respectively.
Fig. 5 .
5Procedures for reducing OH (a, c, and e) as well as CH2O (b, d, and f) PLIF images. (g) is the estimated heat release rate. (h) presents the preheat (cyan), reaction (red), and combustion products (yellow) zones. Process (1) corresponds to the background noise, laser profile, and laser pulse energy corrections. Process 2 pertains to applying the median-based filters as well as a global threshold. Process 3 corresponds to estimation of the heat release rate from the processed OH and CH2O PLIF images. The results pertain to U5H40T1 condition.
. The results correspond to φ = 0. 7 .
7Please note that using the conventional method for calculation of HRR (i.e. α = β = 1 [9, 12, 60, 61, 65, 77, 82-84]) leads to similar results and the non unity values of α and β do not influence the conclusions of the present study.Figure 5(g) presents the HRR (I HRR ) pertaining to the raw data shown in Figs. 5(a and b).
0.86 0.85 0.84 0.82 0.78 0.73 0.67 0.60
Representative planar laser-induced fluorescence images pertaining to the test conditions of U5H00T0 (Ka = 0.3), U5H40T0 (Ka = 0.1), U35H00T2 (Ka = 76.0), and U35H40T2 (Ka = 40.4) are presentedin the first, second, third, and fourth rows ofFig. 6, respectively. The results in the first and second columns are representative hydroxyl and formaldehyde PLIF data. The third column is the heat release rate estimated utilizing the procedure discussed in Section 3. The corresponding preheat, reaction, and combustion products zones were obtained using the procedure discussed in Section 3, and these zones are shown by the cyan, red, and yellow colors in the last column ofFig. 6, respectively. For both pure and hydrogen-enriched methane-air flames with Ka = 0.3 (U5H00T0) and 0.1 (U5H40T0), both preheat and reaction zones remain relatively thin, see the cyan and red regions inFigs. 6(d and h). However, for both pure and hydrogen-enriched flames,
Fig. 6 .
6Representative OH (first column) and CH2O (second column) PLIF images as well as the HRR (third column). The preheat, reaction, and combustion products zones in the last column are shown by the cyan, red, and yellow colors, respectively. The first, second, third, and fourth rows pertain to test conditions of U5H00T0, U5H40T0, U35H00T2, and U35H40T2, respectively.
reaction (δ F ) zone thicknesses are presented in Figs. 7(a) and (b), respectively. The results in Figs. 7(a) and (b) normalized by the corresponding laminar flame preheat (δ P,L ) and reaction (δ F,L ) zone thicknesses for matching fuel-air equivalence ratio and hydrogen-enrichment percentages are also shown in Figs. 7(c) and (d), respectively. Values of δ P,L and δ F,L are tabulated in
Fig. 7 .
7estimated, and the corresponding error bars were overlaid on Figs. 7(a) and (b), respectively. The probability density functions of the test conditions with the largest instantaneous preheat and reaction zone thicknesses, which correspond to U35H30T2 and U35H10T2 test conditions, are overlaid by the hot color bar (a and b) are the preheat and reaction zone thicknesses. (c and d) are the results in (a and b) normalized by δP,L and δF,L. Figs. 7(a) and (b), respectively.
Fig. 8 .
8equivalence ratios of 0.65, 0.85, and 1.05, and those of[21] pertain to φ = 0.4, 0.7, and 1.0. Comparison of our results with those of Skiba et al.[9] and Wang et al.[21] at a similar fuel-air equivalence ratio (0.65 and 0.7) suggests that the values of δ P /δ P,L nearly collapse. The results show that, for both pure and hydrogenenriched methane-air flames, the preheat zone features broadening, and this becomes more pronounced with increasing the turbulence intensity. The broadening of the preheat zone for hydrogen-enriched methane-Variation of the normalized preheat zone thickness versus u Λ/(SL,0δL) for all tested conditions. The dashed line of u Λ/(SL,0δL) = 180 is the border proposed in[9] and Driscoll et al.[3].
Fig. 9 .
9(a) Mean normalized local consumption speed (ST,LC/SL,0) versus u /SL,0. (b) presents the results in (a) color coded based on the corresponding tested integral length scale.
η min and η max are the extents of the η−axis in the domain of investigation. For a relatively large domain of investigation, the left hand side of Eq. (2) does not change by extending the bounds of integration. The turbulent flame burning rate (B T ) is defined as the spatially averaged (along ξ) value of B T,ξ (ξ) and is given by . (3), ξ min and ξ max correspond to the boundaries of ξ−axis in the domain of investigation. In the denominator of Eq. (3), L ξ,T is the length of c OH = 0.5 contour and depends on the tested condition. Similarly, the laminar flame burning rate can be estimated from
(a). The maximum uncertainty associated with calculation of B T /B L pertains to test condition of U35H00T2, which is shown by the error bar in the figure. Among the formulations proposed in the literature, see for example the review paper by Driscoll [2], derivation of the global consumption speed formulation does not necessarily depend on the flamelet assumption, and as a result, S T,GC /S L,0 can be compared to B T /B L . Since the field of view of the present investigation is relatively small, the normalized global consumption speed values cannot be estimated for the present investigation; however, S T,GC /S L,0 associated with the studies of [21, 40] are overlaid on Fig. 10 by the red dotted-dashed and blue dotted curves. Two trends can be observed for the variation of the normalized burning rate.
Fig. 10 .
10(a) Variation of the normalized burning rate (BT/BL) versus u /SL,0. (b) is the results in (a) color-coded based on the tested integral length scale.
Fig. 11 .
11The normalized burning rate predicted by Eq. (6) (or the normalized global consumption speed) divided by the normalized local consumption speed versus turbulence intensity.
. 12. The ratio of the normalized burning rate and the normalized local consumption speed versus (a) the preheat and (b) the reaction zone thicknesses normalized by those of the corresponding laminar flame counterparts. Overlaid on (b) is the linear fit to the data.
Fig. 13 .
13Comparison of the burning rate values estimated from Eqs.(6) and(9).
Fig. 14 .
14The difference between the normalized burning rate estimated based on the prediction of Damköhler's first hypothesis and the experimental results of the present study. Also overlaid on the figures are the results from the studies of[21,40].
Fig. 15 .Fig. 16 .
1516Variations (N OH/N OH ) −1 versus (a) D and (b) u /SL,0. The results in (c) are those in (b) color-coded based on the corresponding tested integral length scale values.As this parameter increases, the possibility of local extinction occurrence increases, the fuel can potentially escape from the flame region, decreasing the generated heat release rate, and as a result the pronounced deviation of the burning rate from the prediction of the Damköhler's first hypothesis shown inFig. 14. It is of interest to develop a model that allows for predicting the effect of governing parameters on the occurrence of local extinctions, the bending behavior, and as a result the burning rate. To address these, first, the results presented inFig. 15(b) are color-coded based on the corresponding tested integral length scale and presented in Fig. 15(c). As evident in the inset of the figure, (N OH /N OH ) −1 does not change by changing the integral length scale at relatively small values of u /S L,0 . However, at relatively large values of the turbulence intensity, decreasing the integral length scale increases the values of (N OH /N OH ) −1 (compare the values of this parameters at u /S L,0 ≈ 20 and at different integral length scales). At relatively small turbulence intensities, the turbulent eddies cannot penetrate into the flame zone, local extinctions rarely occur, and the values of (N OH /N OH ) −1 are relatively small and nearly independent of the tested integral length scales. However, at larger values of u /S L,0 , eddies feature relatively large rotational kinetic energy and can penetrate into the flame zone [11]. At large values of u /S L,0 , decreasing the integral length scale facilitates penetration of relatively small scale eddies into the flame zone, increasing the occurrence of local extinctions, and as a result the larger values of (N OH /N OH ) −1 and D shown in Figs. 15 and 14(b). In essence, the above argument suggests that both (N OH /N OH ) −1 and D should be positively (negatively) correlated with u /S L,0 (Λ). To investigate this, variations of (N OH /N OH ) −1 and D versus (u /S L,0 )(Λ/δ L ) −1 are presented in Figs. 16(a) and (b), respectively. The parameter (u /S L,0 )(Λ/δ L ) −1 is similar to that used for calculation of the Karlovitz number, however, different exponents for u /S L,0 and Λ/δ L are used here. This is because, when presented against (u /S L,0 )(Λ/δ L ) −1 (compared to the Karlovitz number), both (N OH /N OH ) −1 and D variations collapse. Using the least-square technique, a second order polynomial curve was fit to the variation of D versus (u /S L,0 )(Λ/δ L ) −1 , Variations of (a) (N OH/N OH ) −1 and (b) D with (u /SL,0)(Λ/δL) −1 .
(12), Term I pertains to the Damköhler's first hypothesis, and Term II highlights the negative contribution of bending to the normalized burning rate of turbulent premixed flames. To assess prediction of Eq.(12), first, values of the normalized burning rate color-coded based on the normalized integral length scale are presented in Fig. 17. Then, the values of B T /B L obtained from Eq. (12) are overlaid on the figure for several values of Λ/δ L by the dotted-dashed curves. The prediction of Damköhler
Fig. 17 .
17burning rate versus u /S L,0 features a parabolic behavior. For extremely large values of u /S L,0 , the effect of Term II in Eq.(12) becomes dominant, which is equivalent to pronounced occurrences of local extinctions, leading to decrease of B T /B L .The bending behavior and decrease of the burning rate due to local extinctions are consistent with the results of past studies, see for example[7,26,[102][103][104]. The implication of Eq. (12) prediction and the results The normalized burning rate versus turbulence intensity. The dotted-dashed curves pertain to the prediction of Eq.(12). The dashed line is the prediction of the Damköhler's first hypothesis[50].
of 22.2 mm. The burner schematic and the burner nozzle technical drawing are shown in Figs.1 and 2(a),
respectively. A mixture of 75% hydrogen and 25% methane (volumetric percentages) is injected through the
burner rim, generating a pilot flame, see Fig. 1. Similar to [11], the volumetric flowrate of the pilot flow is
only 2% of the main flow, which is small, and as a result, the pilot flame is not expected to influence the main
Bunsen flames. In order to generate a relatively wide range of turbulence intensities, three different turbulence
M 1
M 1
M 1
M 1
P
P
P
M 2
M 2
M 2
M 3
M 2
M 3
L 1
L 1
L 1
L 2
L 2
L 2
L 3
L 3
L 3
C 1
C 2
C 3
C 4
Burner
PI V
las er
HG
Dy e las er
Du al-hea d
Nd :Y AG las er
CH4 +H2
CH 4 +H 2 +Air
FOV
28 3 nm
35 5 nm
53 2 nm
532 nm
HG: Harmonic generator
C 1 : OH ICCD camera
C 2 : CH 2 O ICCD camera
C 3 and C 4 : sCMOS cameras
FOV: Field of view
P: Photodiode
M 1 : 532 nm mirror
M 2 : 355 nm mirror
M 3 : 283 nm mirror
L 1 : -25 mm cylindrical lens
L 2 : 400 mm cylindrical lens
L 3 : 1000 mm cylindrical lens
Table 2 .
2Values of α and β used for calculation of heat release rate. Results pertain to φ = 0.7.
Table 3 .
3Preheat and reaction zone thicknesses at the smallest tested mean bulk flow velocity and with no turbulence generator.U5H00T0 U5H10T0 U5H20T0 U5H30T0 U5H40T0 U5H50T0 U5H60T0 U5H70T0
δ P,L (mm)
0.60
0.58
0.54
0.50
0.47
0.43
0.39
0.41
δ F,L (mm)
0.50
0.47
0.47
0.46
0.48
0.49
0.50
0.55
Overlaid on Fig. 7(c) are the normalized preheat zone thickness pertaining to the studies of Skiba et al. [9],
AcknowledgmentsThe authors would like to thank financial support from the Mitacs Accelerate program, the Gas Turbine
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Turbulent burning velocities: A general correlation in terms of straining rates. R G Abdel-Gayed, D Bradley, M Lawes, Proc. R. Soc. A. 414R. G. Abdel-Gayed, D. Bradley, M. Lawes, Turbulent burning velocities: A general correlation in terms of straining rates, Proc. R. Soc. A 414 (1847) (1987) 389-413.
How fast can we burn?. D Bradley, Proc. Combust. Inst. 241D. Bradley, How fast can we burn?, Proc. Combust. Inst. 24 (1) (1992) 247-262.
| Abstract For large hydrocarbon fuels used in internal combustion engines, different low-temperature and high-temperature chemistries are involved in the autoignition processes under different initial temperatures. As one of the simplest fuels with low-temperature chemistry, dimethyl ether (DME) is considered in this study and one-dimensional autoignitive reaction front propagation induced by temperature gradient is simulated for stoichiometric DME/air mixtures considering detailed chemistry and transport. The emphasis is placed on assessing and interpreting the influence of initial temperature on the detonation development regime. Different initial temperatures below, within and above the negative-temperature coefficient (NTC) region are considered. For each initial temperature, four typical autoignition modes are identified: supersonic autoignitive reaction front (without detonation); detonation development; transonic reaction front; and subsonic reaction front. The detonation development regimes for two fuels, DME and n-heptane, at the same initial temperature and those for the same fuel, DME, at three different initial temperatures respectively below, within and above the NTC region are obtained. Based on these results, the influence of fuel type and initial temperature on detonation development regime are discussed. It is found that the detonation development regime becomes narrower at higher initial temperature. Moreover, the influence of initial temperature on reaction front propagation speed is investigated. The reaction front propagation speed is shown to be strongly affected by different chemistries involved in low and high temperature regions. When only the high-temperature chemistry is involved, the reaction front propagation speed is shown to be less dependent on the initial temperature. | Abstract Results of experiments and data analysis on turbulent flame propagation in obstructed channels are presented. The data cover a wide range of mixtures: H 2 /air, H 2 /air/steam (from lean to rich) at normal and elevated initial temperatures (from 298 to 650 K) and pressures (from 1 to 3 bar); and stoichiometric H 2 /O 2 mixtures diluted with N 2 , Ar, He and CO 2 at normal initial conditions. The dataset chosen also covers a wide range of scales exceeding two orders of magnitude. It is shown that basic flame parameters, such as mixture expansion ratio σ , Zeldovich number β and Lewis number Le , can be used to estimate a priori a potential for effective flame acceleration for a given mixture. Critical conditions for effective flame acceleration are suggested in the form of correlations of critical expansion ratio σ ∗ versus dimensionless effective activation energy. On this basis, limits for effective flame acceleration for hydrogen combustibles can be estimated. Uncertainties in determination of critical σ ∗ values are discussed. | The oxygen-enriched combustion has a great interest for industrial applications, since membrane separation technology can be achieved. One of the objectives of this work is to provide unique data of the laminar burning velocity for oxygen-enriched combustion of iso-octane/air mixture for varied dilution (by air or CO2) cases. The isooctane was mixed with a mixture of O2, CO2 and N2. The volume fraction of O2 was varied from 21% to 29% and CO2 was varied from 0% to 28%. By using detail kinetics mechanism with Senkin tool, auto-ignition delay was investigated for the same mixtures to get better understanding of the engine knock. Theoretically, with the increase of O2, the increase of laminar burning velocities prevents knock apparitions, meanwhile, the decrease of auto-ignition delay favourite knock events, inversely with the increase of CO2. | 1,999,768 | As a fundamental study in the application to direct-injection spark-ignition engines or gas turbines, in which mixture stratification and partial quenching are of serious concerns, unsteady premixed methane/ air flames subjected to time-varying composition fluctuations are investigated computationally. The code OPUS employs an unsteady opposed-flow combustion configuration, including detailed chemical kinetics, transport, and radiation models, using an adaptive time integration method for a stiff system of differential-algebraic equations with a high index. The primary issue of the study is to establish the concept of the dynamic flammability limit , defined as the minimum equivalence ratio above which the unsteady flame can sustain combustion. For the weak and strong strain rate cases studied, it is observed that the dynamic flammability limit depends on the mean and frequency of the composition fluctuation. The parametric study demonstrated that the flammability limit of an unsteady premixed flame is further extended to a leaner condition as the frequency or mean equivalence ratio fluctuation increases. It is also found that, under all conditions, the mean equivalence ratio and the minimum flame temperature must be higher than those at the steady flammability limit to sustain combustion. It is further shown that the dynamic flammability limit is primarily determined by the instantaneous, branching-termination balance at the reaction zone. The behavior of the flame response attenuation with increasing frequency is found to scale properly using the normalized frequency based on the imposed flow strain rate, which represents the characteristic time scale of the transport process within the flame. | With detailed chemical kinetics being employed in combustion simulations, its major computational challenge is the time-intensive nature of chemical kinetics integration due to the large number of chemical species and wide range of chemical timescales involved. In this work, an extended tabulated dynamic chemistry approach with dynamic pruning method is carried out to simulate complex spray combustion for non-premixed combustion process. The thought of extended tabulated dynamic chemistry approach with dynamic pruning is achieved by selecting the optimum acceleration method as well as its error tolerances at different combustion stages depending on combustion characteristics involving the low-temperature combustion. The present method is applied to realistically complex combustion systems involving spray flame of n-heptane fuel and non-premixed combustion engine. Computation efficiency of the proposed method is compared with the results using different accelerating methods, including dynamical adaptive ch... | Abstract The effects of operating conditions and turbulence on flame front position, turbulent flame speed and flame brush thickness of lean premixed methane/air flames at high pressure are investigated experimentally. A comparison of the measured turbulent flame speeds with existing correlations is presented and discussed. The measurements were performed in an axis-symmetric, generic combustor at pressures up to p = 1.44 MPa, equivalence ratios in the range Φ = 0.43–0.56, preheating temperatures T = 673–773 K and for an inlet bulk velocity range of u BULK = 30–60 m/s. The turbulence intensity and the integral length scale at the combustor inlet were varied by means of turbulence grids with different geometry and by changing the grid position in the inlet channel. The isothermal flow field was characterized by two-dimensional particle image velocimetry (PIV). The characterization of the flame front was based on the statistical analysis of two-dimensional instantaneous images of the laser induced fluorescence of the OH radical (OH-PLIF). The analyses revealed that pressure has no effect on the flame front position, the turbulent flame speed, or on the flame front fluctuation (flame brush thickness). Decreasing the fuel concentration from Φ = 0.43 to Φ = 0.56 results in a flame elongation by a factor of 2 and a corresponding decrease of the turbulent flame speed by a factor of 3. For the same variation of the fuel concentration the flame brush thickness increases by a factor of 2. Additionally, the flame brush thickness was consistently observed to vary proportionally to the square root of the flame front position. The experimental values of the turbulent flame speed are in satisfactory agreement with the existing correlations. | Flammability limit and limit-temperature of counterflow lean methane-air flames | The paper presents the results of investigation of combustion features of a fuel-lean methane-air swirling flame in a model combustion chamber using numerical simulation at an elevated pressure and initial temperature of the mixture. The equivalence ratio is 0.7, the initial temperatures of the mixture are 300 and 500 K, and the overpressure corresponds to 2 and 4 bars. Setting the increased pressure as the output boundary conditions in the numerical simulation of combustion in a model combustion chamber is shown to be efficient. It is found that a change in the initial temperature of the mixture from 300 to 500 K (at a fixed Reynolds number equal to 30000) leads to a significant change in the combustion regime. So, in the case of the initial temperature of the mixture equal to 300 K, the recirculation zone is formed only near the walls of the combustion chamber, and the flame has a compact shape, and is stabilized inside the premixer. With elevated initial temperatures of the mixture, a stagnation region is formed on the jet axis, and the flame displacement downstream relative to the premixer exists. | Turbulent Flame Velocities in Premixed Sprays Part I. Experimental Study | In this study, a single-cylinder direct-injection spark-ignition research engine with full optical access was used to investigate the influence of the flow field and fuel/air mixing on cyclic variability, in particular in the early flame propagation. The engine was operated under lean-burn conditions at 1500 rpm. Two different injection strategies were compared, port-fuel injection (PFI) and direct injection (DI), the latter with early and late injection split about 2:1 in fuel mass. High-speed particle image velocimetry captured the flow in the tumble plane in the compression stroke. The velocity fields and the movement of the tumble vortex are analyzed. Simultaneously, a second camera detected the chemiluminescence of the flame, and the projected area of the line-of-sight-integrated flame luminosity was extracted through morphological image processing. By combining pressure-based combustion analysis and high-speed optical diagnostics, the early flame propagation and the flow field are correlated. In separate experiments the equivalence ratio was imaged for the DI at selected crank angles and correlated with CA10 to learn about the influence of mixture inhomogeneity on early flame propagation. With PFI, the flow near the spark plug just before ignition is closely related to the subsequent speed of combustion. The combustion-relevant flow features can be traced back in time to about -90 °CA. In contrast, the chosen DI scheme results in a decorrelation of flow and flame, and the equivalence ratio distribution at ignition becomes more important. For both flow and mixture fields, regions of high correlation with early-combustion metrics are typically associated with gradients in the multi-cycle average fields. | We extend an investigation into the static and dynamic multiplicity exhibited by the reaction of a fuel/air mixture in a continuously stirred tank reactor by considering the effect of adding a chemically inert species to the reaction mixture. The primary bifurcation parameter is taken to be the fuel fraction as this is the most important case from the perspective of fire-retardancy. We show how the addition of the inert species progressively changes the steady-state diagrams and flammability limits. We also briefly outline how heat-sink additives can be incorporated into our scheme. | Results of direct numerical simulations of turbulent premixed combustion of methane-air mixture at model conditions in simple cubic computational domain at moderate Reynolds number Reλ~50 and Karlovitz number Ka~5 are presented. These conditions correspond to combustion regime with main oxidation reactions localized in thin area. Extended kinetic mechanism of methane oxidation is used for chemical reactions description. Laminar flame velocity values are obtained and compared with other results of 1D and 3D calculations. Thickness, form and local flame front structures are revealed based on computation results. |
1,999,769 | who did john shakespeare lend money to in the play | Shakespeare in Love is a 1998 romantic period comedy-drama film directed by John Madden, written by Marc Norman and playwright Tom Stoppard, and produced by Harvey Weinstein. It stars Gwyneth Paltrow, Joseph Fiennes, Geoffrey Rush, Colin Firth, Ben Affleck and Judi Dench.
The film depicts a fictional love affair involving playwright William Shakespeare (Joseph Fiennes) and Viola de Lesseps (Gwyneth Paltrow) while Shakespeare was writing Romeo and Juliet. Several characters are based on historical figures, and many of the characters, lines, and plot devices allude to Shakespeare's plays.
Shakespeare in Love received acclaim from critics and was a box office success, grossing $289.3 million worldwide and was the ninth highest-grossing film of 1998. The film received numerous accolades, including seven Oscars at the 71st Academy Awards, including Best Picture, Best Actress (Gwyneth Paltrow), Best Supporting Actress (Judi Dench), and Best Screenplay Written Directly for the Screen.
Plot
In 1593 London, William Shakespeare is a sometime player in the Lord Chamberlain's Men and playwright for Philip Henslowe, owner of The Rose Theatre. Suffering from writer's block with a new comedy, Romeo and Ethel, the Pirate's Daughter, Shakespeare attempts to seduce Rosaline, mistress of Richard Burbage, owner of the rival Curtain Theatre, and to convince Burbage to buy the play from Henslowe. Shakespeare receives advice from rival playwright Christopher Marlowe, but is despondent to learn Rosaline is sleeping with Master of the Revels Edmund Tilney. The desperate Henslowe, in debt to ruthless moneylender Fennyman, begins auditions anyway.
Viola de Lesseps, daughter of a wealthy merchant, who has seen Shakespeare's plays at court, disguises herself as a man named Thomas Kent to audition. Kent gains Shakespeare's interest with a speech from Two Gentlemen of Verona, but runs away when Shakespeare questions her. He pursues Kent to Viola's house and leaves a note with her nurse, asking Kent to begin rehearsals at the Rose.
Shakespeare sneaks into a ball at the house, where Viola's parents arrange her betrothal to Lord Wessex, an aristocrat in need of money. Dancing with Viola, Shakespeare is struck speechless. After introducing himself as Christopher Marlowe, Shakespeare is ejected by Wessex, who threatens to kill him. Shakespeare finds Viola on her balcony, where they confess their mutual attraction before he is discovered by her nurse and flees.
Inspired by Viola, Shakespeare quickly transforms the play into what will become Romeo and Juliet. Rehearsals begin, with Thomas Kent as Romeo, the leading tragedian Ned Alleyn as Mercutio, and the stagestruck Fennyman in a small role. Shakespeare discovers Viola's true identity, and they begin a secret affair.
Viola is summoned to court to receive approval for her proposed marriage to Wessex. Shakespeare accompanies her, disguised as her female cousin, and persuades Wessex to wager £50 that a play can capture the true nature of love, the amount Shakespeare requires to buy a share in the Chamberlain's Men. Queen Elizabeth I declares that she will judge the matter.
Burbage learns Shakespeare has seduced Rosaline and cheated him out of payment for the play, and starts a brawl at the Rose with his company. The Rose players repel Burbage and his men and celebrate at the pub, where a drunken Henslowe lets slip to Viola that Shakespeare is married, albeit separated from his wife. News arrives that Marlowe has been murdered. A guilt-ridden Shakespeare assumes Wessex had Marlowe killed, believing him to be Viola's lover, while Viola believes Shakespeare to be the victim. Shakespeare appears at her church, allaying Viola's fears and terrifying Wessex, who believes he is a ghost. Viola confesses her love for Shakespeare, but both recognize she cannot escape her duty to marry Wessex.
John Webster, an unpleasant boy who hangs around the theatre, spies on Shakespeare and Viola making love and informs Tilney, who closes the Rose for breaking the ban on women actors. Viola's identity is exposed, leaving Shakespeare without a stage or a lead actor, until Burbage offers his theatre and the heartbroken Shakespeare takes the role of Romeo. Following her wedding, Viola learns the play will be performed that day, and runs away to the Curtain. She overhears that the boy playing Juliet cannot perform, his voice having broken, and Henslowe asks her to replace him. She plays Juliet to Shakespeare's Romeo to an enthralled audience.
Just after the play has concluded, Tilney arrives to arrest everyone for indecency due to Viola's presence, but the Queen reveals herself in attendance and restrains him, pretending that Kent is a man with a "remarkable resemblance" to a woman. Powerless to end a lawful marriage, she orders Viola to sail with Wessex to Virginia. The Queen also tells Wessex, who followed Viola to the theatre, that Romeo and Juliet has won the bet for Shakespeare, and has Kent deliver his £50 with instructions to write something "a little more cheerful next time, for Twelfth Night".
Viola and Shakespeare say their goodbyes, and he vows to immortalise her, as he imagines the beginning of Twelfth Night, in character as a castaway disguised as a man after a voyage to a strange land.
Cast
Production
The original idea for Shakespeare in Love was suggested to screenwriter Marc Norman in the late 1980s by his son Zachary. Norman wrote a draft screenplay which he presented to director Edward Zwick, which attracted Julia Roberts, who agreed to play Viola. However, Zwick disliked Norman's screenplay and hired the playwright Tom Stoppard to improve it (Stoppard's first major success had been with the Shakespeare-themed play Rosencrantz and Guildenstern Are Dead).
The film went into production in 1991 at Universal, with Zwick as director, but although sets and costumes were in construction, Shakespeare had not yet been cast, because Roberts insisted that only Daniel Day-Lewis could play the role. Day-Lewis was uninterested, and when Roberts failed to persuade him, she withdrew from the film, six weeks before shooting was due to begin. The production went into turnaround, and Zwick was unable to persuade other studios to take up the screenplay.
Eventually, Zwick got Miramax interested in the screenplay, but Miramax chose John Madden as director. Miramax boss Harvey Weinstein acted as producer, and persuaded Ben Affleck to take a small role as Ned Alleyn. Kate Winslet was offered the role of Viola after the success of Titanic, but she rejected it to pursue independent films. Winona Ryder, Diane Lane and Robin Wright were also considered for the lead role.
Principal photography began on March 2, 1998, and ended on June 10, 1998.
The film was considerably reworked after the first test screenings. The scene with Shakespeare and Viola in the punt was re-shot, to make it more emotional, and some lines were re-recorded to clarify the reasons why Viola had to marry Wessex. The ending was re-shot several times, until Stoppard eventually came up with the idea of Viola suggesting to Shakespeare that their parting could inspire his next play.
Among the locations used in the production were Hatfield House, Hertfordshire (for the fireworks scene), Broughton Castle, Oxfordshire (which played the role of the de Lesseps home), the beach at Holkham in Norfolk, the chapel at Eton College, Berkshire, and the Great Hall of Middle Temple, London.
References to Elizabethan literature
Much of the action of the film echoes that of Romeo and Juliet. Will and Viola play out the famous balcony and bedroom scenes; like Juliet, Viola has a witty nurse, and is separated from Will by a gulf of duty (although not the family enmity of the play: the "two households" of Romeo and Juliet are supposedly inspired by the two rival playhouses). In addition, the two lovers are equally "star-crossed"they are not ultimately destined to be together (since Viola is of rich and socially ambitious merchant stock and is promised to marry Lord Wessex, while Shakespeare himself is poor and already married). Rosaline, with whom Will is in love at the beginning of the film, is a namesake of Romeo's love-interest at the beginning of the play. There are references to earlier cinematic versions of Shakespeare, such as the balcony scene pastiching the Zeffirelli Romeo and Juliet.
Many other plot devices used in the film are common in Shakespearean comedies and other plays of the Elizabethan era: the Queen disguised as a commoner, the cross-dressing disguises, mistaken identities, the sword fight, the suspicion of adultery, the appearance of a ghost (cf. Macbeth), and the "play within a play". According to Douglas Brode, the film deftly portrays many of these devices as though the events depicted were the inspiration for Shakespeare's own use of them in his plays.
Christopher Marlowe is presented in the film as the master playwright whom the characters consider the greatest English dramatist of that time – this is historically accurate, yet also humorous, since the film's audience knows what will eventually happen to Shakespeare's reputation. Marlowe gives Shakespeare a plot for his next play, "Romeo and Ethel the Pirate's Daughter" ("Romeo is Italian...always in and out of love...until he meets...Ethel. The daughter of his enemy! His best friend is killed in a duel by Ethel's brother or something. His name is Mercutio.") Marlowe's Doctor Faustus is quoted repeatedly: "Was this the face that launched a thousand ships/ And burned the topless towers of Ilium?" A reference is also made to Marlowe's final, unfinished play The Massacre at Paris in a scene wherein Marlowe (Rupert Everett) seeks payment for the final act of the play from Richard Burbage (Martin Clunes). Burbage promises the payment the next day, so Marlowe refuses to part with the pages and departs for Deptford, where he is killed. The only surviving text of The Massacre at Paris is an undated octavo that is probably too short to represent the complete original play. It has been suggested that it is a memorial reconstruction by the actors who performed the work.
The child John Webster (Joe Roberts), who plays with rats, is a reference to a leading figure in the next, Jacobean, generation of playwrights. His plays (The Duchess of Malfi, The White Devil) are known for their 'blood and gore', which is humorously referred to by the child saying that he enjoys Titus Andronicus, and also saying of Romeo and Juliet, when asked his opinion by the Queen, "I liked it when she stabbed herself."
When the clown Will Kempe (Patrick Barlow) says to Shakespeare that he would like to play in a drama, he is told that "they would laugh at Seneca if you played it", a reference to the Roman tragedian renowned for his sombre and bloody plot lines which were a major influence on the development of English tragedy.
Will is shown signing a paper repeatedly, with many relatively illegible signatures visible. This is a reference to the fact that several versions of Shakespeare's signature exist, and in each one he spelled his name differently.
Plot precedents and similarities
After the film's release, certain publications, including Private Eye, noted strong similarities between the film and the 1941 novel No Bed for Bacon, by Caryl Brahms and S. J. Simon, which also features Shakespeare falling in love and finding inspiration for his later plays. In a foreword to a subsequent edition of No Bed for Bacon (which traded on the association by declaring itself "A Story of Shakespeare and Lady Viola in Love") Ned Sherrin, Private Eye insider and former writing partner of Brahms', confirmed that he had lent a copy of the novel to Stoppard after he joined the writing team, but that the basic plot of the film had been independently developed by Marc Norman, who was unaware of the earlier work.
The film's plot can claim a tradition in fiction reaching back to Alexandre Duval's "Shakespeare amoureux ou la Piece a l'Etude" (1804), in which Shakespeare falls in love with an actress who is playing Richard III.
The writers of Shakespeare in Love were sued in 1999 by bestselling author Faye Kellerman. She claimed that the plotline was stolen from her 1989 novel The Quality of Mercy, in which Shakespeare romances a Jewish woman who dresses as a man, and attempts to solve a murder. Miramax Films spokesman Andrew Stengel derided the claim, filed in the US District Court six days before the 1999 Academy Awards, as "absurd", and argued that the timing "suggests a publicity stunt". An out-of-court settlement was reached, but the sum agreed between the parties indicates that the claim was "unwarranted".
Historical inaccuracies
The film is "not constrained by worries about literary or historical accuracy" and includes anachronisms such as a reference to Virginia tobacco plantations, at a time before the Colony of Virginia existed. A leading character is an Earl of Wessex, a title which in Shakespeare's time had not existed for over 500 years. Queen Elizabeth I never entered a public theatre, as she does in the film. Between Romeo and Juliet and Twelfth Night, Shakespeare wrote ten other plays over a period of six years. The biggest historical liberty concerns the central theme of Shakespeare struggling to create the story of Romeo and Juliet, as in real life he simply adapted an existing story for theatre. The Italian verse tale The Tragical History of Romeus and Juliet had been translated into English by Arthur Brooke in 1562, 32 years before Shakespeare's Romeo and Juliet.
Reception
Janet Maslin made the film an "NYT Critics' Pick", calling it "pure enchantment". According to Maslin, "Gwyneth Paltrow, in her first great, fully realized starring performance, makes a heroine so breathtaking that she seems utterly plausible as the playwright's guiding light." Roger Ebert, who gave the film four stars out of four, wrote: "The contemporary feel of the humor (like Shakespeare's coffee mug, inscribed 'Souvenir of Stratford-Upon-Avon') makes the movie play like a contest between Masterpiece Theatre and Mel Brooks. Then the movie stirs in a sweet love story, juicy court intrigue, backstage politics and some lovely moments from Romeo and Juliet... Is this a movie or an anthology? I didn't care. I was carried along by the wit, the energy and a surprising sweetness."
Rotten Tomatoes gives the film a 92% approval rating based on 141 critical reviews, with an average rating of 8.30/10. The website's critical consensus states: "Endlessly witty, visually rapturous, and sweetly romantic, Shakespeare in Love is a delightful romantic comedy that succeeds on nearly every level." On Metacritic, the film holds a score of 87 out of 100 based on 33 critical reviews, indicating "universal acclaim".
Shakespeare in Love was among 1999's box office number-one films in the United Kingdom. The U.S. box office reached over $100 million; including the box office from the rest of the world, the film took in over $289 million.
The Sunday Telegraph claimed that the film prompted the revival of the title of Earl of Wessex. Prince Edward was originally to have been titled Duke of Cambridge following his marriage to Sophie Rhys-Jones in 1999, the year after the film's release. However, after watching Shakespeare in Love, he reportedly became attracted to the title of the character played by Colin Firth, and asked his mother Queen Elizabeth II to be given the title of Earl of Wessex instead.
In the wake of sexual abuse allegations against Weinstein, many of the cast and crew began to distance themselves from the producer and his past behavior. Madden, while condemning Weinstein, stated that the producer "craved power and had power and, as we now know, he was using it in ways that are repugnant and should be utterly condemned".
Best Picture and Best Actress Oscar controversy
Shakespeare In Love won the Best Picture Oscar at the 71st Academy Awards, controversially beating critically favored Saving Private Ryan and becoming the first comedy to win the award since Annie Hall (1977). The Academy's decision was criticized by many for awarding the film over Saving Private Ryan, and Gwyneth Paltrow winning Best Actress over frontrunner Cate Blanchett for Elizabeth.
Many industry pundits speculated that this win was attributed to the awards campaign led by Weinstein. Weinstein was reported to have strong-armed the movie's talent into participating in an unprecedented blitzkrieg of press. Terry Press, an executive at DreamWorks at the time, stated that Weinstein and Miramax "tried to get everybody to believe that Saving Private Ryan was all in the first 15 minutes". Mark Gill, an executive at Miramax at the time, claimed that Weinstein had a reliance on relatively cheap publicity. He stated, "This was not saying to the stars, 'O.K., you can go on a couple of talk shows to open the movie and do a weekend of interviews at a junket and thanks so much for helping, Gill said. "That was just 'Good morning. You've got three more months of shaking hands and kissing babies in you.
In 2015, The Hollywood Reporter magazine, claiming to have interviewed "hundreds" of Academy members, indicated that, having to choose between Shakespeare in Love and Saving Private Ryan, a majority of them would award the Oscar for Best Picture to the latter.
Accolades
In 2005, the Writers Guild of America ranked its script the 28th greatest ever written.
American Film Institute recognition:
AFI's 100 Years...100 Passions – #50
Stage adaptation
Lee Hall's Shakespeare in Love
In November 2011, Variety reported that Disney Theatrical Productions intended to produce a stage version of the film in London with Sonia Friedman Productions. The production was officially announced in November 2013. Based on the film screenplay by Norman and Stoppard, it was adapted for the stage by Lee Hall. The production was directed by Declan Donnellan and designed by Nick Ormerod, the joint founders of Cheek by Jowl.
The production opened at the Noël Coward Theatre in London's West End on 23 July 2014, receiving rave reviews from critics. It was called "A joyous celebration of theatre" in the Daily Telegraph, "Joyous" in The Independent, and "A love letter to theatre" in The Guardian.
Japanese Adaptation
From December 2016 to January 2017, Shakespeare of True Love (), a Japanese adaptation of Shakespeare in Love written by Shigeki Motoiki and Sakurako Fukuyama, was produced in Kanagawa Arts Theatre. It was not related to Lee Hall's play. Takaya Kamikawa played Will Shakespeare and Alisa Mizuki played Viola.
See also
BFI Top 100 British films
References
External links
Official website for stage adaptation
1998 films
1990s historical romance films
1990s romantic comedy-drama films
American films
American historical romance films
American romantic comedy-drama films
British films
British historical romance films
British romantic comedy-drama films
BAFTA winners (films)
Best Film BAFTA Award winners
Best Musical or Comedy Picture Golden Globe winners
Best Picture Academy Award winners
Cross-dressing in American films
Cross-dressing in British films
English-language films
Films about actors
Films about Elizabeth I
Films about William Shakespeare
Films based on Romeo and Juliet
Films directed by John Madden
Films featuring a Best Actress Academy Award-winning performance
Films featuring a Best Musical or Comedy Actress Golden Globe winning performance
Films featuring a Best Supporting Actress Academy Award-winning performance
Films produced by Harvey Weinstein
Films produced by David Parfitt
Films set in London
Films set in the 1590s
Films set in Tudor England
Films that won the Best Original Score Academy Award
Films whose art director won the Best Art Direction Academy Award
Films whose writer won the Best Original Screenplay Academy Award
Miramax films
Films with screenplays by Tom Stoppard
Films scored by Stephen Warbeck
Universal Pictures films
Films adapted into plays
1998 comedy films
1998 drama films
Films about writers | AbstractThis essay situates Shakespeare’s two most ‘economic’ plays, The Merchant of Venice and Timon of Athens, in the context of contemporary debates on usury and other relevant aspects of the market economy that ushered in the transition from a feudal economy to a capitalist one in sixteenth-century England. The debates resulted in the statute of 1571 that legalised money-lending, provided that it did not exceed a maximum interest rate, fixed by the State, of 10%. This settlement was the result of a cultural as well as ideological compromise between Christian and market values that legitimised a capitalist economy while at the same time defusing its disruptive aspects. The author argues that Shakespeare’s two plays offer a dramatic reflection on the advent of a market-based economy in England and the cultural negotiations underpinning it; a reflection that also involves a critical examination of the social relations, in both the public and private spheres, that emerged alongside the new market economy.... | originally performed by the Lady Elizabeth's Men. Andrew Crooke issued another quarto edition in 1661. The play was included in the second Beaumont and Fletcher folio of 1679. "Wit Without Money" is one of the few plays known to have been performed during the English Civil War and the Interregnum period, 1642–60, when the London theatres were formally closed but operated when they could (an early form of "guerilla theatre"). The play was staged at the Red Bull Theatre on 3 February 1648; unable to sell tickets openly, the actors had tickets thrown into the gentry's coaches. Another performance, on | What skills did actors need in the shakespeare plays? | Shakespeare in Love play from Henslowe. Shakespeare receives helpful advice on his play from rival playwright Christopher "Kit" Marlowe, but becomes despondent when he learns Rosaline is sleeping with Edmund Tilney, the powerful Master of the Revels. Henslowe, who is in debt to the ruthless moneylender Fennyman and in desperate need for a new play, begins auditions anyway. Viola de Lesseps, the daughter of a wealthy merchant, who has seen Shakespeare's plays at court, disguises herself as a man named Thomas Kent to audition. "He" gains Shakespeare's interest when he auditions with a speech from Two Gentlemen of Verona after a series of | to raise funds towards the restoration and reopening of the famed theatre. The ShakesBeer Festival held on Aug 23, 2014 raised over 30K and donated 20K to the restoration efforts after final expenses. This event is designed to be an annual event in order to bring in a source of revenue to the theatre, and raise awareness. American Shakespeare Theatre The American Shakespeare Theatre was a theater company based in Stratford, Connecticut, United States. It was formed in the early 1950s by Lawrence Langner, Lincoln Kirstein, John Percy Burrell and philanthropist Joseph Verner Reed. The American Shakespeare Festival Theatre was | Hamlet (1948 film) of the play, broadcast on the program "Theatre Guild on the Air". Gielgud also followed the lead of Olivier's film version by giving the final lines of the play to Horatio instead of to Fortinbras. Olivier also played up the Oedipal overtones of the play by having Hamlet kiss his mother lovingly on the lips several times during the film. Film scholar Jack Jorgens has commented that "Hamlet's scenes with the Queen in her low-cut gowns are virtually love scenes." In contrast, Jean Simmons' Ophelia is destroyed by Hamlet's treatment of her in the nunnery scene. According to J. Lawrence | Which two books did shakespeare use as general references for his history plays? | 1,999,769 | to over £50,000 in 2007), including interest, to a Walter Mussum. Mussum was not a good risk; at his death his whole estate was worth £114, or barely half what John Shakespeare had seen fit to lend him. The financial risk was just one side of his potentially problematic business activity. The law described usury as "a vice most odious and detestable" and levied severe penalties for those caught in such practices, even in a small way. The law stated that anyone caught lending money with interest illegally would forfeit all the money lent, plus forfeiture of any interest due, | Moral Failure Behind the Financial Failure | what was the name of the law that prohibited money market funds from paying interest | Secretly eloped for financial reasons and regretting not doing everything “right” | what happens to the security interest if the proceeds fall short of the obligations | are farrow and ball in financial trouble? | which type of fraud involves a debtor who gives his assets to an outsider | Hugh Levey owes an investment firm $1.3 million after a bad investment .
Manhattan Judge Shirley Kornreich ruled that Levey must pay up .
Instead of paying Levey made public his affair which ended his marriage . | Financial infidelity |
1,999,770 | Intratumoral Accumulation and Clonal Expansion May Not Be Decisive for Rejection of Allogeneic Tumors by CD8+ T-Lymphocytes | Progress in Allogeneic Hematopoietic Cell Transplantation in Adult T-Cell Leukemia-Lymphoma | Progress in Allogeneic Hematopoietic Cell Transplantation in Adult T-Cell Leukemia-Lymphoma | CD8 T cell activation after intravenous administration of CD3×CD19 bispecific antibody in patients with non-Hodgkin lymphoma | Adoptive transfer of antigen-specific CD4+ and CD8+ T cells is one of the most efficient forms of cancer immunotherapy. However, the isolation of antigen-specific CD4+ T cells is limited because only few tumor-associated helper epitopes are identified. Here, we used T cell antigen receptor gene transfer to target CD4+ T cells against an MHC class I-presented epitope of a model tumor antigen. IFN-γ-producing CD4+ T cells were unable to expand in vivo and to provide help for tumor rejection. In contrast, CD4+ T cells producing high levels of IL-2 expanded in vivo, provided help for cytotoxic T lymphocyte-mediated tumor rejection, and developed T cell memory. The data demonstrate in vivo synergy between T cell antigen receptor-transduced CD4+ and CD8+ T cells specific for the same epitope resulting in long-term tumor protection. | Breast carcinomas are often infiltrated by inflammatory cells, particularly macrophages and T lymphocytes, but the significance of these cells remains unclear. One possible role of these inflammatory cells is that they represent a cell-mediated immune response against the carcinoma. CD8+ lymphocytes are a known crucial component of cell-mediated immunity. The purpose of this study was to explore the prognostic value of tumor-infiltrating CD8+ cytotoxic lymphocytes in breast cancer. Tumor-infiltrating CD8+ lymphocytes were assessed by immunohistochemical staining of tissue microarray cores from 1,334 unselected breast tumors from patients with long-term follow-up. The number of CD8+ T cells was counted in tumor nests (intratumoral), in stroma adjacent to tumor cells, and in stroma distant to tumor cells, and their relationship with clinical outcome was determined. The total number of CD8+ cells was positively correlated with tumor grade (rs = 0.20; P < .001) and inversely correlated with patient's age at d... |
Background
Adoptive immunotherapy is currently an attractive approach to cancer treatment. It is defined as the application of expanded/manipulated immune cells adoptively transferred to a cancer patient to eliminate tumor cells, which can be used as a stand-alone treatment or in combination with traditional methods of radiotherapy, chemotherapy, and surgery [1,2]. One of the interesting modalities of adoptive immunotherapy is the adoptive transfer of T cells as the key player of anti-tumor immunity [3,4]. The three T cells of interest in this approach include tumor-infiltrating lymphocytes, T cell receptor T cells (TCR T cells), and chimeric antigen receptor T cells (CAR T cells), the latter of which has sparked greater attention among researchers and clinicians [5,6]. To deliver an effective adoptive T cell transfer, adequate expansion of cells is an essential step. This may not be an issue for hematological malignancies in which remission is not closely correlated with the number of T cells. However, T cell dose is particularly important in solid tumors where, in some cases, a few hundred billion T cells are required [7]. Accordingly, an efficient T cell expansion method to produce such numbers is a prerequisite of a successful ACT.
Most ACT protocols include isolating and in vitro expanding peripheral mononuclear cells (PBMCs). In order to produce polyclonal T cells, resting T cells must first be activated using a primary and secondary signal through CD3 and CD28 stimulation, respectively. T cell activation can be achieved using anti-CD3 antibodies (OKT3) and irradiated feeder cells; however, a more accessible strategy to activate T cells is simply adding small magnetic beads coated with anti-CD3/CD28 antibodies [8]. Beads are substitutes for antigen-presenting cells (APCs) and are one of three activation methods approved for clinical trials, which can be coated with any antibodies, are simple to use and remove, and can be used to separate any T cell subset [9]. The number of beads to cells, called bead-to-cell ratio, is a determinant of signal strength and consequently T cell expansion. While extremely high bead-to-cell ratio results in T cell exhaustion, too low ratios fail to activate T cells, both resulting in a suboptimal T cell expansion [10]. After activation, cells are seeded in culture plates. The number of cells seeded per mL is another determinant of effective cell expansion outcome, which has been previously shown in studies using osteoblasts, mesenchymal and adipose stem cells, and human umbilical vein endothelial cells [11][12][13][14]. For T cells, however, the optimized condition of successful expansion has not been clearly defined.
T cells require growth factors to expand, which are catered by the medium and serum. One growth factor is interleukin-2 (IL-2), which by binding to its receptor promotes the polyclonal expansion of T cells through binding to its cell surface receptor. Subsequently, the complex is quickly internalized, and then the α subunit (CD25) resurfaces to bind to IL-2. Hence, in an expansion course, it is pivotal to replenish IL-2 in the culture medium every 2-3 days [15]. Studies have used a wide range of 20 to 7200 IU/mL of IL-2 concentration for T cell expansion [16], though their difference in expansion efficacy is not clear.
Despite the improvement of T cell expansion protocols over the years, the optimum conditions for expansion are still elusive since there are many determinant factors. Hence, this study was designed to investigate the optimum condition for polyclonal T cell expansion with regards to three essential factors, i.e., IL-2 concentration, seeding density, and bead-to-cell (B:C) ratio.
Results
Morphological observations
Within the first 2 h of culture, cells started to form clusters of cells. This was evident in either low-and highdensity wells or low and high B:C ratios; however, it was clear that the higher the density or the B:C ratio was the more aggregates were observed. Since the cells' capacity to proliferate diminishes after 21 days and the beads are not replenished after day 0, cells fail to form clusters in the final weeks. We also observed an increase in the size of mononuclear cells 3-4 days after the addition of beads (Fig. 1). This was seen in both the microscopic view and the forward and side scatter plots of T cells in flow cytometry.
The effect of IL-2 on T cell expansion
Five groups were assigned to determine the effect of varying IL-2 concentrations on T cell expansion. Cells supplemented with 20 IU/mL of IL-2 had the lowest expansion rate compared to other groups, which was statistically significant. When the IL-2 concentration increased to 50 IU/mL, the expansion rate significantly increased in comparison to 20 IU/mL (p = 0.02). Although a further increase in IL-2 concentration resulted in more expansion rate, on day 28, there was no difference between cells cultivated in 500 IU/mL compared to 50 (p = 0.7), 100 (p = 0.8), and 200 IU/ mL (p = 0.84) (Fig. 2).
The effect of seeding density on T cell expansion T cells expanded in different cell densities showed diverse results. The cells seeded at 250 × 10 3 cell/mL and cells seeded at 1.5 × 10 6 cell/mL led to the highest and lowest expansion rates, respectively. An increase in the number of seeded cells from 62 × 10 3 cell/mL to 250 × 10 3 cell/mL gradually improved expansion rate; however, further increases resulted in lower T cell expansions. On day 28, cells seeded at 250 × 10 3 cell/mL resulted in significantly higher fold expansions compared with seeding densities of 62 × 10 3 (p = 0.007), 500 × 10 3 (p = 0.025), 1 × 10 6 (p = 0.008), and 1.5 × 10 6 (p < 0.0001) cell/mL. However, the difference was not significant compared to the seeding density of 125 × 10 3 cell/mL (Fig. 3).
The effect of bead-to-cell ratio on T cell expansion T cell expansion showed a direct correlation to the B:C ratio. Therefore, the 10:1 B:C ratio and 1:10 B:C ratio resulted in the highest and lowest fold expansions at the ninth time point. On day 28, the differences between fold expansions of 1:10 and 1:5 (p = 0.9), 1:5 and 1:2 (p = 0.9), 1:2 and 1:1 (p = 0.9), 1:1 and 2:1 (p = 0.95) groups were not significant. The cells stimulated with a 5:1 B:C ratio resulted in significantly more fold expansions compared with those stimulated with 2:1 (p < Fig. 1 The microscopic view of PBMCs on day 0 (a) and the expanded T cells on day 3 (b). After activation with anti-CD2/CD3/CD28 coated beads, cell sizes considerably increased 0.0001). Stimulation with a 10:1 B:C ratio provided no significantly higher expansion rate than stimulation with 5:1 (p = 0.087) (Fig. 4).
Comparison of expansion rates in three donors
In order to determine the reproducibility of results, the PBMCs of three donors in the condition with the highest yield of expansion plus one level higher and one level lower as per each determinant factor were cultured, and their results were compared with each other. When comparing IL-2 concentrations, 20 IU/mL IL-2 was found to be the least potent concentration for T cell expansion in all three donors ( Fig. 5a, b). In donors 1 and 3, 100 IU/mL IL-2 expanded more T cells compared to 50 IU/mL IL-2, and conversely, 50 IU/mL showed slightly more expansion potential than 100 IU/mL in donor 2, but none of these differences were statistically significant. Comparing the T cell expansions of the three donors according to seeding densities of 125 × 10 3 , 250 × 10 3 , and 500 × 10 3 cell/mL, 250 × 10 3 cells/mL seeding resulted in higher expansion rates (p < 0.0001) (Fig. 5c, d). Finally, expansions of PBMC of three donors using 2:1, 5:1, and 10:1 B:C ratio showed that 2:1 ratio led to the lowest expansion rate and there was no difference between 5:1 and 10:1 ratio in the donors (Fig. 5e, f).
Immunophenotyping results
Immunophenotypic analysis showed the presence of 56-57% CD3 + cells in the PBMCs prior to expansion at day 0 which, after 28 days of expansion in the optimum condition, this number increased to approximately 96% in all donors (Table 1). Moreover, the rate of CD3/CD4 + cells decreased from about 27% at day 0 to 16% at day 28, and the majority of cells in the final time-point were CD3/CD8 + .
Discussion
T-cells have a pivotal role in cellular immunity against tumor cells. One effective approach to cancer treatment would be a method for the isolation and ex vivo expansion of T cells. This requires optimized and highly efficient expansion protocols. To this end, isolated T-cells are first activated and then expanded in a well-defined condition to achieve a great number of cells. However, like many other cells, polyclonal T cell expansion lacks a unanimous efficient protocol [17]. In this study, we tried to optimize the expansion of polyclonal T cells in terms of three important determinants in the expansion of T cells: B:C ratio, IL-2 concentrations, and initial seeding density. We found that cultures in the condition of 250 × 10 3 cells/mL seeding density in a 24-well plate activated with 5:1 B:C ratio and 50 IU/mL IL-2 supplementation provide the most optimal T cell expansion.
IL-2 is a potent cytokine that drives both T cell expansion and differentiation from naive phenotype to stem cell memory T cells (T SCM ), central memory T cells (T CM ), effector memory T cells (T EM ), and finally terminally differentiated effector T cells (T Eff ). T Eff exhibit higher cytotoxic function and homing to peripheral tissues, while T SCM show less senescence and great selfrenewal and persistence [18]. Using other y-chain cytokines such as IL-7 and IL-15 have been proposed to augment T cell expansion and decrease differentiation. Although IL-7/IL-15-treated polyclonal T cells have less differentiation and more anti-tumor efficiency, they either show no significant T cell [19] expansion advantage or a small T cell [20] and CAR T cell expansion [21,22] compared to IL-2 only-treated cells. Kaartinen and colleagues have reported that low IL-2 concentrations (0-5 IU/mL) while displaying meager T cell expansion, favor the less differentiated memory T cells, while higher concentrations (up to 300 IU/mL) produce T Eff populations [16]. They also reported that the T SCM subset was undetectable regardless of IL-2 concentration. Due to the need for high T cell numbers in clinical settings, the trials opt to use all CD3 + populations of T cells for CAR T cell or TCR T cell therapy [23][24][25]. A study in 2002 assessed the expansion of T cells from four donors while ranging IL-2 concentration from 0.2 to 2000 IU/mL. T cells showed a meager expansion at 0.2-20 IU/mL IL-2, as they expanded less than 10 folds. At 100-2000 IU/ mL, T cells showed significant expansion compared to lower concentrations, but there was no difference Fig. 4 CPD results of T cells in various B:C ratio groups. Over the culture period, the highest B:C ratios generated the best expansion results (a). On day 28, a direct correlation between the number of beads and the expansion potential was seen (b) between these groups [26]. Our results showed a higher expansion rate when increasing the IL-2 concentration from 20 to 50 IU/mL, but no significant difference in expansion rate occurred when IL-2 concentrations were further increased. This can be seen as an advantage, since the use of lower IL-2 concentrations not only reduces the costs of immunotherapies but also reduces negative IL-2 withdrawal effects on T cells postexpansion, diminishing T cell exhaustion [27,28]. Moreover, in high IL-2 concentrations, endogenous IL-2 secretion is suppressed by Stat-5 and Blimp-1 proteins in negative feedback [29]. In a study T cells from three donors were expanded at three different concentrations of 20, 100, and 1000 IU/mL of IL-2 for 3 weeks. No Fig. 5 The fold expansion (a, c, e) and CPD (b, d, f) results of the three donors on day 28. Twenty international units per milliliter produced the lowest number of T cells, while the difference between 50 and 100 IU/mL was not significant (a, b). All samples experienced peak expansion in 250 × 10 3 cell/mL (c, d). 2:1 B:C ratio results were lower than the other two, and while 10:1 increased expansion more than 5:1, the difference was not significant (e, f) [30]. In a similar study, Berglund et al. did not find any difference in T cell expansion over a one-week period when IL-2 ranged from 50 to 600 IU/mL [19]. Our findings corroborate these studies. In all cell expansion protocols, seeding density plays an essential role, as it directly affects cell-cell, and in the case of T cell, cell-APC interactions and cytokine exchanges. Based on our findings, too high and too low densities are counterproductive, and equilibrium in cell/ area is key. As we found, for T cell expansion, 250 × 10 3 cells/mL of a 24-well plate is the optimum seeding density. Considering the unique surface area of the wells in a culture plate, the number of wells in each plate may show different results. Ma et al. compared the outcomes of T cell expansion using 1 × 10 6 , 1 × 10 5 , 1 × 10 4 , 1 × 10 3 cell/mL densities in 6-well culture plates in 2 mL of medium and concluded that 1 × 10 6 cell/mL (1 × 10 7 cell/cm 2 ) density produced the best results. The wells in 6-well and 24-well plates have 9.6 and 1.9 cm 2 surface area, respectively. This means that 1 × 10 7 cell/cm 2 in a 6-well plate is approximately equivalent to 200 × 10 4 cell/cm 2 (200 × 10 3 cell/mL) in a 24-well plate, which is closest to our results [31].
Anti-CD3/CD28 coated beads can act as artificial APCs, and so, are indispensable for T cell activation and subsequent expansion. To reveal the optimal B:C ratio with the highest expansion yield, Trickette et al. expanded T cells of four healthy donors at different B:C ratios for 2 weeks. They reported the least expansion in the 1:10 B:C ratio and an increased expansion when increasing the number of beads to 5:1 ratio, which was corroborated by our results [26]. In addition, they found that after expansion, the CD4 + population diminished to less than 15%, and CD8 + T cells constituted the majority of cells, which were also in agreement with our results. Shi et al. compared the expansion potential of 1:5, 1:1, and 3:1 B:C ratio over a 1-week period and reported the best expansion rate in the highest ratio, i.e., 3: 1 ratio, and the least expansion in 1:5 [20]. Moreover, in the 1:5 B:C ratio, the CD3 + population consisted of equal portions of CD4 + and CD8 + cells, which could be due to poor cell expansion. When cells are activated, they require time to undergo the growth phases; hence, we opted to expand T cells for 4 weeks until they reach a plateau phase and compared the results [32]. This is evident in our results when expansion dwindles after 2-3 weeks, which is likely caused by T cells' exhaustion and senescence. Therefore, to prevent ex vivo T cell exhaustion, most protocols opt to expand T cells for less than 2 weeks, because T cells typically lose function after 2 weeks of culture. The function of T cells could have been evaluated in our study by cytotoxicity assays (e.g. LDH assay) to ensure the production of functional T cells.
A step-up from small-scale static culture (e.g. culture plates and flasks) to large-scale T cell expansion would be to use bioreactors to mimic the in vivo environment in which T cells can rapidly proliferate. Although culture plates and flasks are the most traditional culture systems and are considered the gold standard of T cell culture, their efficacy is hindered by limited oxygen transfer, waste and lactate buildup, contamination risk, and lack of agitation. Novel, automated systems are seeking to rectify these issues. For instance, gas-permeable bags allow for a closed, sterile system with low media evaporation and efficient gas exchange but little control over culture parameters [33]. Currently, many commercial bioreactors such as G-REX® systems, a variety of rocking-motion bioreactors, CliniMACS® Prodigy, etc. are created to address the need for large-scale, clinical settings [34].
Conclusion
The optimized culture conditions of T cell expansion are elusive since many different factors contribute to its outcome. Notably, T cell stimulation and co-stimulation methods, various cytokines, growth media and sera, oxygen concentration, ambient pH, initial seeding density, and static or dynamic culture are all elements that affect the result of T cell expansion. Here, we attempted to optimize the most prominent and base T cell culture conditions in laboratory settings. By comprehensive examination of these parameters, we concluded that 250 × 10 3 cell/mL, 50 IU/mL IL-2, and 5:1 B:C ratio for initial activation is the most efficient and ideal condition among these three factors for the expansion of polyclonal T cells.
Methods
PBMC isolation and general T cell culture
This study was approved by the National Committee for Ethics in Biomedical Research (IR.TUMS.S-PH.REC.1397.050). Peripheral blood was drawn from healthy donors after obtaining written informed consent. Before blood collection, the donors were clinically evaluated by a physician, and a complete blood cell count was conducted ( Table 2). All donors were men and within a close range of age. The mononuclear cell portion of the peripheral blood (PBMC) was isolated using a densitygradient separation medium (1.077 g/mL, Ficoll-Hypaque, GE Healthcare, UK). The cell pellet was seeded in a 24-well culture plate containing 2 mL Tex-MACS medium (Miltenyi Biotec, Germany) supplemented with 10% heat-inactivated FBS (Gibco, USA) or platelet lysate (SABZ, Iran), 1X penicillin/streptomycin (Bioidea, Iran), and recombinant human IL-2 (Miltenyi Biotec, Germany). For T cell expansion and activation, T Cell Activation/Expansion Kit (Miltenyi Biotec, Germany) containing anti-CD2, −CD3, and -CD28coated MACSiBead™ particles was used at different B:C ratio depending on the test group, and bead were removed on day 7 using a MACSiMAG™ Separator to prevent autofluorescence and T cell over-activation.
Study grouping
The following groups were selected based on previously published literature and expansion studies in our research laboratory [6,8]. At first, five groups in which IL-2 concentration was the variable were assigned to optimize IL-2 concentration. Secondly, six varying seeding density groups were appointed to discern the highest expansion rate of cell density. Lastly, seven groups of B: C ratio were selected after the result of the previous two experiments.
IL-2 concentration comparative groups
To assess the effect of IL-2 concentration on T cell expansion, PBMCs were seeded at a standard concentration of 1 × 10 6 cells/mL in a 24-well culture plate, and were then stimulated once with microbeads at 1:2 B:C ratio, followed by expansion using five different IL-2 concentrations (20,50,100,200, 500 IU/mL).
Seeding density comparative groups
To assess the effect of seeding density on T cell expansion, PBMCs were seeded at 62 × 10 3 , 125 × 10 3 , 250 × 10 3 , 500 × 10 3 , 1 × 10 6 , and 1.5 × 10 6 cell/mL, and then were stimulated once with microbeads at 1:2 B:C ratio, followed by expansion using 50 IU/mL IL-2 which was selected based on the results from IL-2 concentration comparative groups.
B:C ratio comparative groups
To assess the effect of B:C ratio on T cell expansion, PBMCs were seeded at a concentration of 250 × 10 3 cells/mL in a 24-well culture plate (based on the results of seeding density comparative groups), and were then stimulated once with microbeads at different B:C ratios (1:10, 1:5, 1:2, 1:1, 2:1, 5:1, and 10:1), followed by expansion using 50 IU/mL IL-2 (based on IL-2 concentration comparative groups).
Monitoring T cell proliferation
Throughout the culture process, the cells were counted at nine time points (i.e., days 0, 6, 8, 11, 14, 17, 21, 25, and 28), and cell number was determined via trypan blue exclusion dye. The kinetics of T cell expansion was assessed under different culture conditions by calculating the cumulative population doubling (CPD) and fold expansion. We determined fold expansion by dividing the final cell count by the initial cell number. Population doubling (PD) was calculated using the equation: PD = 3.32 (log N1-logN0), where N0 represents the number of initially seeded cells and N1 represents the number of harvested cells at each time-point, respectively. After counting the cells, a number of cells equal to the initial seeding density of their respective group were subcultured to a new well. The cells were cultured at 37°C in a humidified atmosphere containing 5% CO 2 for 28 days. In all the experiments, 24-well culture plates containing 2 mL of cell and culture media mixture were used. Every 3 days, half the culture medium was replaced with a fresh medium containing the same concentration of IL-2.
Comparison of T cell expansion of three donors in optimal and near-optimal conditions
After determining the best culture condition for the greatest yield of T cell in one donor, in each study group, PBMCs of three different donors, one of whom was the first donor, were expanded and compared in that condition to one level higher and one level lower. In other words, the PBMCs of the donors were seeded at 1 × 10 6 cell/mL, stimulated with beads at 1:2 B:C ratio, and expanded using 20, 50, and 100 IU/mL IL-2. In the next experiment, the PBMCs of the donors were seeded at 125 × 10 3 , 250 × 10 3 , and 500 × 10 3 cell/mL, stimulated with beads at 1:2 B:C ratio, and expanded using 50 IU/mL IL-2. Lastly, PBMCs of the three donors were seeded at 250 × 10 3 cell/mL, stimulated with beads at 2:1, 5:1, and 10:1 B: C ratio, and expanded using 50 IU/mL IL-2 (Fig. 6).
Flow cytometry analysis
Immunophenotyping was performed on PBMCs before expansion and T cells on day 28. Cells were washed in complete medium, and 2 × 10 5 cells were re-suspended in the 100 μl PBS containing 3% Bovine Serum Albumin (Sigma, USA). Then. The cells were incubated with 5 μl of Anti-Human CD3-PerCP (Miltenyi Biotec, Germany), Anti-Human CD4-FITC/CD8-PE (BD Biosciences, USA), Mouse IgG2a Isotype PerCP (Miltenyi Biotec, Germany), Mouse IgG1 Isotype-FITC (BD Biosciences, USA), and Mouse IgG1 Isotype-PE Biosciences, USA) at 4°C in the dark. Cells were analyzed with BD FACSCali-bur™ Flowcytometer (BD Biosciences, USA) for cell surface markers and the data was processed using FlowJo software version X (FlowJo LLC, USA).
Statistical analysis
The difference between cell expansion results was analyzed by Two-Way Repeated Measures ANOVA followed by Tukey post hoc test using GraphPad Prism version 8 for Windows. All the experiments were performed independently in triplicates. P-values less than 0.05 were considered statistically significant.
Received: 24 January 2021 Accepted: 21 June 2021
Fig. 2
2CPD of T cells after expansion with different IL-2 concentrations. The expansion trend in (a) shows increased expansion in higher than 20 IU/mL concentrations. On day 28, there was no significant difference between 50, 100, 200, and 500 IU/mL concentrations (b) Fig. 3 CPD of T cells when cultured in various cell densities. Graph (a) compares the trend of expansion in different groups. On day 28, the highest and lowest expansion rates occurred in 250 × 10 3 and 1.5 × 10 6 cell/mL, respectively (b)
Table 1
1Flow cytometry profile of PBMCs (day 0) and T cells (day 28) of the three donors. The results are shown as mean ± SDCD3 (%)
CD4 (%)
CD8 (%)
CD3/CD4 (%)
CD3/CD8 (%)
CD4/CD8 (%)
PBMC
Donor 1
57 ± 5.7
31.7 ± 2.4
26 ± 2.1
30.9 ± 6.4
21 ± 2
1.2 ± 0.5
Donor 2
56.9 ± 2.4
30.2 ± 2.6
26.9 ± 1.6
27.1 ± 6.1
24.5 ± 1.8
1.7 ± 0.7
Donor 3
56.8 ± 8.5
28.5 ± 4.3
27.4 ± 2.5
26.8 ± 12.8
25.6 ± 2.2
1.1 ± 0.2
T cell
Donor 1
97.5 ± 1.8
19.3 ± 10.5
72.1 ± 19.4
17.3 ± 7.3
70.7 ± 13.4
1.34 ± 0.4
Donor 2
96.6 ± 1.9
16.5 ± 9.9
70.4 ± 15.8
14.7 ± 8.7
65.8 ± 11.5
2.1 ± 0.3
Donor 3
98 ± 1.3
20.4 ± 11.5
69.9 ± 17.7
16.7 ± 9.1
68.7 ± 10.3
1.5 ± 0.5
Table 2
2The baseline demographic and hematological characteristics of the donorsDonor
WBC count (10 3 /μl)
Lymphocyte count (10 3 /μl)
lymphocyte percentage (%)
Sex
Age (year)
1
5.4
1.7
31.2
M
26
2
4.4
2.2
50.6
M
25
3
6.1
1.9
31.6
M
28
Ghaffari et al. BMC Immunology
AcknowledgmentsThe authors acknowledge the help and funding of Tehran University of Medical Sciences for conducting this study.Adherence to guidelinesThe authors confirm that all methods were carried out in accordance with relevant guidelines and regulations.Authors' contributionsAll authors contributed to the study conception and design. The author(s) read and approved the final manuscript.FundingThe research leading to these results received funding from Tehran University of Medical Sciences under Grant Agreement No 954386.Availability of data and materialsThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.DeclarationsEthics approval and consent to participate This study was approved by the National Committee for Ethics in Biomedical Research (IR.TUMS.SPH.REC.1397.050). Informed consent was obtained from all individual participants included in the study.Consent for publicationWritten informed consent for publication of their clinical details and/or clinical images were obtained from the patient/parent/guardian/ relative of the patient. A copy of the consent form is available for review by the Editor of this journal.Competing interestsThe authors have no relevant financial or non-financial interests to disclose.Author details
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| Dendritic cells (DCs) are critical in both initiating adaptive immune responses and maintaining tolerance to self antigens. These apparently contradictory roles have been suggested to depend on different subsets of DCs that arise from either myeloid or lymphoid hematopoietic origins, respectively. Although DC expression of CD8α is attributed to a lymphoid origin, here we show that both CD8α+ and CD8α− DCs can arise from clonogenic common myeloid progenitors in both thymus and spleen. Thus, expression of CD8α is not indicative of a lymphoid origin, and phenotypic and functional differences among DC subsets are likely to reflect maturation status rather than ontogeny. |
Introduction
The role of the immune system in limiting tumor growth, designated as cancer immunosurveillance [1], has been first elucidated in mouse models of immune deficiency characterized by a high incidence of spontaneous and chemically induced tumors [2]. Those studies have identified several components of the innate and adaptive immune response being responsible for tumor elimination, including αβ and γδ T-cells [3], and NK cells [4]. Reinforcing the role of cytotoxic T lymphocytes (CTLs) in the eradication of malignant cells, transgenic mice deficient in perforin, a component of the cytolytic granules of T and NK cells, are more susceptible to spontaneous and chemically induced tumors than their wild type counterparts [5]. In humans, evidence on the role of the immune system in limiting tumor growth and progression is linked to observations indicating a positive correlation between the presence of tumor infiltrating CD8+ T-cells and good prognosis in various types of cancer. In colorectal cancer, for example, significantly higher levels of early memory and effector memory CD8+ T-cell infiltrates positively correlate with good clinical outcome, defined as absence of metastatic invasion, less advanced pathological stage, and increased survival [6,7]. Similarly, the presence of intraepithelial tumor infiltrating CD8+ T-cells has been associated with the lack of tumor metastases in the draining lymph nodes of cervical cancer patients [8]. In non-small cell lung carcinoma patients, increasing numbers of tumor infiltrating CD8+, CD20+, and CD4+ T lymphocytes have also been shown to significantly correlate with improved disease-specific survival [9]. Altogether, these observations support a role for the immune system in controlling tumor burden and form the rationale for the development of vaccine-based interventions against cancer that rely on the stimulation of an effective antitumor immune response in the host.
The immune system, however, has two paradoxical roles in cancer. While various components of the innate and adaptive immune response are able to mediate tumor cell destruction, specific types of immune cells can also induce a protumor environment that favors tumor growth and the development of metastasis [10]. Among the latter are, for example, regulatory T (Treg) cells [11,12], tumor associated macrophages (TAM) [13,14], and type 2 helper CD4+ (Th2) 2 Journal of Biomedicine and Biotechnology T-cells [15,16]. These various immune cells have been shown to accumulate at the site of the tumor, negatively impacting the establishment of antitumor T-cell responses, that is, creating an immunosuppressive tumor environment.
Cancer cells themselves are also equipped with mechanisms that allow them to evade recognition by the immune system or to negatively affect the functionality of effector T-cells. In order to avoid immune recognition, tumor cells have been shown to downregulate antigen expression, components of the antigen-processing and presentation machinery, and expression of major histocompatibility complex (MHC) molecules [17]. Decreased expression of costimulatory molecules of crucial importance to T-cell activation, and enhanced surface expression of molecules that negatively regulate activation of T-cells, such as PD-L1/B7-H1 and B7-H4, have also been demonstrated in various types of tumors [18][19][20]. Cancer cells can also restrain the function of the immune system by secreting a milieu of soluble factors that ultimately inhibit the activation, proliferation, and differentiation of the various components of the immune response. Among these molecules are TGFβ [21], IL-10 [22], IL-13 [23], and VEGF [24].
The goal of vaccine-based cancer immunotherapy approaches is to induce a tumor-specific immune response that ultimately will reduce tumor burden by tipping the balance from a protumor to an antitumor immune environment ( Figure 1). This review discusses strategies employed in the field of cancer vaccines aimed at enhancing activation of tumor-specific T-cells with concurrent reduction of immunosuppression. Specifically, vaccine design, immune adjuvants, and multimodal approaches using vaccines in combination with other treatment modalities will be discussed here, with a particular emphasis on studies conducted at the National Cancer Institute, NIH.
Vaccine Design: Choice of Vaccine-Delivery System(s)
Depending on the vaccine-delivery system of choice, cancer vaccines can elicit an immune response against an individual or multiple tumor antigens. A list of the various types of vaccine-delivery systems under investigation in the field, either at the preclinical or clinical stages, is presented in Table 1. Multiple studies have demonstrated that combinations of some of the strategies in the form of diversified prime/boost regimens may enhance the outcome of the intervention against the tumor [25]. Moreover, it has also been shown that concurrent vaccination with two distinct vaccine platforms targeting the same antigen can elicit a more diverse population of antigen-specific T-cells thus resulting in higher antitumor immunity [26].
Among the various types of vaccine delivery systems, there are strategies based on the use of whole tumor cells, dendritic cells-(DCs-) tumor cell fusions, or preparations of DCs loaded with tumor protein lysates or tumor-derived RNA (Table 1, left column). These vaccine platforms induce an immune response against multiple tumor targets, either known or unknown. Other vaccine modalities (Table 1, right column) are based on the previous characterization of tumor antigens to be used as "specified" targets in the vaccine formulation.
Tumor Antigens
Tumor antigens are molecules either exclusively expressed in the tumor cells, designated as "tumor-specific antigens", or molecules that are overexpressed in cancerous versus normal tissues, designated as "tumor-associated antigens". A comprehensive list of tumor antigens and their corresponding Tcell epitopes can be found at [27,28]. Table 2 shows a brief list of selected examples for either type of antigen. Tumorspecific antigens appear de novo after cancer cells acquire mutations within the coding regions of certain genes, for example the oncogene ras [29] and the tumor suppressor p53 [30], or novel fusion proteins are generated as in the case of the Bcr-Abl fusion in chronic myeloid leukemia [31]. Moreover, in tumors driven by infectious agents like human papillomavirus (HPV) or Epstein-Barr virus (EBV), virallyderived products become de novo targets of T-cell immune responses directed against the tumor. The majority of tumorassociated antigens so far identified have a certain level of expression in normal tissues and thus tolerance to these antigens often exists. A strategy used by tumors to escape immune recognition and destruction is the complete or partial loss of an antigen(s) [17]. Both in experimental animal models [32,33], and in human cancer [34], it has been shown that "antigen-negative tumor variants", characterized by the loss of the targeted antigen, can emerge subsequently to an immune intervention. An approach to overcome this problem is the targeting of "functionally relevant antigens", which are proteins with an essential role during tumor initiation, growth, survival, or metastasis [35]. It can be hypothesized that an immune intervention directed against a functioning tumor antigen would greatly reduce the emergence of antigen-negative variants, since cells that lose the antigen will fail to grow, survive, or metastasize.
Targeting of Molecules that Control Metastatic Dissemination
In order to achieve the various steps along the metastatic cascade, epithelial tumor cells may need to undergo a phenotypic conversion into mesenchymal cells via a process designated as epithelial-to-mesenchymal transition (EMT) [36]. The EMT program involves the downregulation of epithelial proteins such as E-cadherin and cytokeratins, and the upregulation of mesenchymal proteins including Fibronectin, N-cadherin, and Vimentin. Various genes normally expressed in the early embryo have been implicated in the control of the EMT triggered during tumor progression, including Twist, Snail, Slug, Goosecoid, and SIP1 [36,37]. The transcription factors encoded by these genes can impart to tumor cells the traits of mesenchymal cells, including motility and the ability to invade the extracellular matrix (ECM). The expression of Twist, for example, has been found to be elevated in various types of cancer, including breast, prostate, and cervical cancer, with higher levels of Twist protein being detected in prostate cancer tissues of high Gleason score [38,39]. Since the EMT process appears to be a necessary step for tumor cells to initiate the metastatic cascade [37,40], interfering with EMT in early stages of the disease is likely to prevent tumor cell spreading and might also be effective in treating established metastatic lesions ( Figure 2). An example of a tumor antigen with a functionally relevant role in the EMT program is the T-box transcription factor Brachyury, highly expressed in various human tumors of epithelial origin, but not in most human normal adult tissues [41]. It has been recently demonstrated that Brachyury overexpression in epithelial tumor cells induces an EMT, promoting the expression of mesenchymal markers and downregulation of epithelial markers, with concomitant increase in tumor cell migration and invasion [42]. Additionally, stable silencing of Brachyury expression in Brachyury-positive human carcinoma cells has been shown to downregulate mesenchymal markers Vaccine strategies aimed at blocking metastasis by targeting of molecules that control the EMT process and upregulate epithelial markers with simultaneous loss of cell migration and ECM invasion. In vivo, Brachyuryinhibited human tumor cells had a decreased ability to form experimental lung metastases after intravenous injection, as well as to disseminate from the primary, subcutaneous tumor to the site of metastases [42]. A CD8 T-cell epitope of Brachyury capable of expanding Brachyury-specific Tcells from the peripheral blood of cancer patients was recently identified [41]; Brachyury-specific T-cells have been used to efficiently lyse Brachyury-positive tumor cells in vitro. The successful expansion of T-cells directed against the transcription factor Brachyury exemplifies the ability of T-cell mediated immunotherapies to target (a) highly conserved tumor proteins, and (b) tumor proteins irrespective of their cellular localization. Because of its relevant role during tumor progression, Brachyury is an appealing tumor antigen for interventions aimed at interfering with the metastatic spreading of tumor cells ( Figure 2). Additionally, the transcription factors Twist, Snail, and Slug, among others, which are critically involved in the control of EMT during tumor progression, could also be explored as novel tumor antigens for the targeting of metastatic disease.
Antigen Cascade
A phenomenon observed with cancer vaccines is the induction of immune responses to tumor antigens that are not present in the vaccine formulation. For example, it has been shown that CEA-transgenic mice cured of CEA-positive tumors by a CEA/TRICOM vaccine regimen were able to subsequently reject CEA-positive as well as CEA-negative tumors, and that this effect was mediated by the generation of specific T-cell immune responses directed against gp70, an antigen expressed by the tumor but not present in the vaccine [43]. The same phenomenon has also been reported in clinical studies [44,45]. Altogether these studies showed that the immune response initiated against a tumor antigen included in the vaccine formulation is then followed by cross-priming and initiation of an "antigen cascade" that expands the immune response to additional antigens expressed on the tumor, thus potentiating antitumor immunity.
Enhancing Activation of Tumor-Specific T-Cells: The Use of Costimulation in the Vaccine Formulation
Optimal activation of T-cells is known to require at least two signals. The first signal is mediated by the interaction between the peptide/MHC complex on the surface of antigen presenting cells (APC) and the T-cell receptor (TCR) on the surface of T-cells. The second signal, also designated as costimulation, is mediated by the interaction between accessory molecules located on the surface of the APC and their corresponding ligand(s) on the T-cells [46]. Activation via the TCR in the presence of adequate costimulatory signals results in the clonal expansion, differentiation, and expression of effector functions by antigen-specific T-cells.
Optimization of the mechanism of T-cell activation is critical to achieve a successful immune response to an antigen included in a vaccine formulation. A list of various strategies being explored in the field of cancer vaccines to achieve enhanced antitumor immune responses is presented in Table 3. One of them is the delivery of a single or multiple costimulatory molecules along with the tumor antigen as part of the vaccine formulation. One of the most studied Tcell costimulatory molecules is B7-1 [47,48]. In preclinical studies it has been shown that mice immunized with an admixture of recombinant vaccinia (rV-) viruses encoding for a tumor antigen (rV-CEA or rV-MUC-1) and the costimulatory molecule B7-1 (rV-B7-1) generate effective antigen-specific T-cell immune responses that translate into successful antitumor immunity [49]. Furthermore, it was demonstrated that combinations of various costimulatory Journal of Biomedicine and Biotechnology 5 molecules act synergistically to further enhance antigenspecific T-cell responses. Using recombinant vaccinia and fowlpox viruses encoding for the tumor antigen CEA and three different costimulatory molecules (B7-1, ICAM-1, LFA-3, designated as TRICOM), T-cell responses against the tumor antigen were further enhanced above the level observed when only one costimulatory molecule was used [50]. In preclinical studies with human T-cells in vitro, enhanced activation of antigen-specific T-cells was observed against DCs modified by infection with rF-TRICOM [51]. Moreover, the same vector was successfully used to enhance the antigen-presentation potency of freshly isolated B cells, resulting in enhanced activation of antigen-specific T-cell responses in vitro [52]. Results from a Phase II randomized clinical trial in 125 metastatic prostate cancer patients were recently reported [53]; patients were randomized to receive either a vaccine regimen consisting of two recombinant viral vectors each encoding for prostate specific antigen (PSA) and the TRICOM molecules (rV-PSA/TRICOM and rF-PSA/TRICOM), or control empty vector (control arm). The results from this trial demonstrated a 44% reduction in the death rate and an 8.5 month improvement in median overall survival (OS) in men in the vaccine compared to the control arm [53]. Additionally, NCI also reported the results from a randomized Phase II trial in 32 patients with metastatic castrate-resistant prostate cancer, who received a prime with rV-PSA/TRICOM and booster vaccinations with rF-PSA/TRICOM. Twelve of 32 patients showed declines in serum PSA post-vaccination; patients with greater PSAspecific T-cell responses showed a trend toward enhanced survival. In general, there was evidence of enhanced median overall survival, particularly among patients with more indolent type of disease [54]. Overall, cancer vaccine strategies incorporating costimulatory molecules have demonstrated the generation of antitumor immunity and evidence of clinical benefit in cancer patients.
The Use of Cytokines as Vaccine Adjuvants
7.1. Cytokines that Affect the APCs. Biological adjuvants are agents generally used for improving the immunogenicity of an antigen in a vaccine formulation. Several cytokines have the ability to enhance immune responses by either (a) promoting the differentiation, activation, or recruitment of APC, therefore enhancing antigen presentation and activation of antigen-specific T-cell responses, or (b) by directly acting on various subsets of T-cells. Within the first group, one of the most studied cytokines is the granulocyte-macrophage colony-stimulating factor (GM-CSF). It has been demonstrated in preclinical studies that subcutaneous injections of GM-CSF at the vaccination site can significantly increase the infiltration of DCs in regional lymph nodes that drain the site of vaccination [55,56]. In several preclinical studies, tumor cells or DCs genetically engineered to secrete biologically active GM-CSF have been used to generate a systemic antitumor immune response [57,58]. The use of GM-CSF at high doses, however, could be detrimental in the context of vaccines since it may result in immune suppression via the activation and expansion of myeloid-derived suppressor cells [59]. In the clinical setting, two placebo-controlled Phase III trials in patients with hormone-refractory prostate cancer, for example, have been performed with an autologous DC-based vaccine, designated Sipuleucel-T, which is genetically modified to express prostatic acid phosphatase (PAP) as a tumor antigen, and GM-CSF. Results from the initial trial with 127 patients [60] demonstrated a 4.5-month improvement in median survival in the vaccine versus placebo group, though without meeting the primary endpoint of time to progression. Results from a subsequent Phase III, placebo-controlled trial measuring overall survival as the primary endpoint have been recently reported [61], indicating a statistically significant survival advantage in patients in the vaccine versus placebo group.
Cytokines that Affect the T-Cell Compartment.
The second group includes cytokines that directly affect the T-cell compartment by promoting T-cell proliferation, activation, and effector function. Among these, the cytokines IL-2 [62,63], IL-7 [64], IL-15 [65,66], and IL-12 [67] are currently under investigation to enhance antitumor immune responses elicited by a vaccine. The most used of these cytokines is IL-2, a T-cell growth factor which, as a single agent, has demonstrated clinical responses in patients with metastatic renal cell carcinoma [68] and metastatic melanoma [69]. A disadvantage, however, in the use of IL-2 therapy in vivo, particularly with high-dose IL-2, is the rate of associated toxicities [70]. Moreover, IL-2 mediates not only the proliferation of activated, effector T-cells and NK cells, but also the development and homeostasis of regulatory T-cells (Tregs), which constitutively express elevated levels of the IL-2R alpha (CD25) [71]. In vitro, IL-2 has also been used to expand tumor-specific T-cells to be used for adoptive immunotherapy [72]. The cytokines IL-15 and IL-7 are also T-cell growth factors; their function, however, is different to that of IL-2 in vivo. IL-15 is necessary for the development and homeostasis of memory CD8 T-cells and NK cells [65]. It has also been demonstrated a role for IL-15 in the induction of long-lived, high avidity CD8 T-cells [73,74] and, unlike IL-2, there is no role for IL-15 on the proliferation of Tregs. Up to date, studies with IL-15 as an adjuvant for cancer vaccine strategies have only been conducted in preclinical models, with encouraging results [67]. The cytokine IL-7, another T-cell growth factor, targets a different population of T-cells, promoting the expansion of naïve T-cells and thus increasing the diversity of T-cell repertoire after lymphopenia [64,65]. IL-7 has also demonstrated positive results as an adjuvant cytokine for cancer vaccine interventions in preclinical studies [67].
Another cytokine that is under investigation as a vaccine adjuvant is IL-12, which promotes Th1 polarization, proliferation of activated T-cells and NK cells, and cell-mediated immunity. IL-12 has been shown to have potent antitumor effects in preclinical models [75]. In humans, however, the systemic delivery of IL-12 has resulted in elevated toxicities [76], hence leading towards the investigation of alternative modes for local delivery of IL-12. For example, in preclinical studies, a coformulation of IL-12 with chitosan intravesically delivered was well tolerated and very efficient at curing mice with superficial bladder cancer. A durable antitumor immune response was also generated in mice receiving IL-12/chitosan, providing them with complete protection from intravesical tumor rechallenge [77]. Overall, the use of cytokines as vaccine adjuvants to enhance the immune response to a tumor is a very promising and active field of investigation. Current research is focused on understanding the proper ways of delivery for each particular cytokine in order to maximize the immune adjuvant effects while reducing potential toxicities, when used in combination with various types of vaccine platforms.
Vaccine Plus Radiation
As it was mentioned above, a mechanism by which tumor cells escape immune recognition and attack is through the downregulation of tumor antigens, MHC expression, or various components of the antigen processing/presentation machinery. A strategy to overcome these obstacles is the use of radiation on tumor cells. Radiation is the standard of care for many types of cancer because of its direct cytotoxic effect on the tumor or its palliative effects on the patient. It has been recently reported that local irradiation of tumors with doses insufficient to induce tumor cell death could result in changes on the phenotype of the tumor cells that include the upregulation of MHC, Fas, ICAM-1, and various tumor associated antigens [78][79][80]. As a result of these changes, irradiated tumor cells are more susceptible to Tcell mediated immune attack. In preclinical studies with a murine colon carcinoma tumor model, sublethal, local tumor irradiation significantly improved the therapeutic efficacy of a recombinant rV-/rF-CEA/TRICOM vaccine regimen against CEA-positive tumors in CEA-transgenic mice [81], while radiation alone or vaccine alone had no effect on tumor growth. In the clinical setting, the approach has been investigated in a phase II clinical trial in patients with localized prostate cancer, randomized to receive a PSAbased poxviral vaccine plus radiotherapy versus radiotherapy alone [82]. The results from this trial indicated increases in PSA-specific T-cell responses of at least 3-fold in patients in the combination arm; the authors also reported evidence of de novo generation of T-cells to well-described prostateassociated antigens not found in the vaccine, providing indirect evidence of immune-mediated tumor killing. These studies thus demonstrated a new paradigm for the use of local tumor irradiation in combination with active vaccine therapy to elicit an effective antitumor immune response.
Vaccines Plus Cytotoxic Drugs
Because of the widespread use of chemotherapy for the treatment of most malignancies, it is rational to design combinatorial approaches using vaccines plus standard chemotherapeutic agents. Like radiotherapy, the use of various types of chemotherapy in combination with vaccines has resulted in enhanced antitumor immune responses. Although the mechanisms involved vary among the various types of cytotoxic drugs employed, in general, drugs can: (a) induce "immunogenic death" of tumor cells, leading to activation of DCs followed by antigen presentation to Tcells [83,84], or (b) modulate the phenotype of the tumor cells making them more susceptible to immune-mediated killing. For example, it has been shown that treatment of human colon carcinoma cell lines with 5-fluorouracil or cisplatin enhances their lytic sensitivity to antigen-specific CD8+ cytotoxic T lymphocytes, by inducing expression of ICAM-1 and Fas [85]. Similarly, treatment of renal cell carcinoma cells with subtoxic concentrations of adriamycin has been shown to upregulate the expression of ICAM-1 and LFA-3, as well as to enhance T-cell mediated killing, Fas-mediated, and TRAIL-mediated killing of tumor cells [86]. Taxanes, on the other hand, are a widely used type of chemotherapeutic agents known to have various effects on the immune system, promoting macrophage activation and release of inflammatory cytokines at the tumor site, thus enhancing tumor lysis [87]. In preclinical studies with CEA-transgenic mice transplanted with CEA-positive tumor cells, enhanced antitumor effect was achieved by using a combination of a rV-/rF-CEA/TRICOM vaccine regimen plus docetaxel, compared to that of vaccine or docetaxel alone [88]. In preclinical models as well, cyclophosphamide, doxorubicin, and paclitaxel have all been shown to enhance the antitumor immune response elicited with a GM-CSFsecreting, HER2/neu-expressing whole-tumor cell vaccine in tumor bearing neu-transgenic mice [89]. The authors were able to demonstrate that the increased antitumor effects in the combination group (vaccine plus drugs) were due to enhanced vaccine efficacy rather than a direct cytolytic effect of the drugs on cancer cells [89].
Altogether, these studies demonstrated that, if used in appropriate schedule and at the correct doses, chemotherapeutic agents could enhance antitumor responses when used in combination with cancer vaccine modalities. Therefore, Journal of Biomedicine and Biotechnology 7 further studies investigating optimum schedules and dosing for various chemotherapeutic agents are needed in order to optimize the use of different cytotoxic agents in combination with cancer vaccines.
Vaccine Plus Small Molecule Targeted Therapies
As the molecular pathways involved in the various steps of carcinogenesis and tumor progression are being elucidated with the advent of sophisticated genetic and molecular techniques, a novel group of therapeutic cancer drugs aimed at inhibiting specific molecular pathways is emerging, designated as small molecule targeted therapies. These drugs are also now being investigated for their immune-modulatory functions to be potentially used in combination with cancer vaccines. For example, the anticancer agent lenalidomide (Revlimid, Celgene Corp., NJ, USA), which is FDA approved for the treatment of patients with multiple myeloma, has been shown to have several immune-modulatory effects that include costimulatory effects on CD3-activated T-cells, augmentation of NK cell cytotoxicity, and suppression of Treg cells proliferation and function [90,91]. Results from a study combining a small molecule BCL-2 inhibitor and a rV-/rF-CEA/TRICOM vaccine regimen were recently reported [92]. It has been shown that, when administered after the vaccine, the BCL-2 inhibitor GX15-070 was able to increase the intratumoral ratio of activated, CD8+ T effector to Treg cells, thus resulting in significant reduction of pulmonary tumor nodules in a mouse model of experimental lung tumors [92]. As with chemotherapeutic agents, the use of small molecule targeted therapies could also be associated with potential toxicities and, in particular, with negative effects on the immune compartment. Thus, further studies investigating optimum schedules and dosing for various small molecule targeted drugs are needed in order to optimize their use in combination with cancer vaccines.
Inhibition of Coinhibitory Signals
An alternative strategy to enhance the outcome of an antitumor immune approach is to eliminate negative signals imparted to T-cells by coinhibitory molecules such as B7-H1, B7-H4, and cytotoxic T-lymphocyte antigen-4 (CTLA-4), among others. B7-H1 is constitutively expressed in many types of human tumors and has been shown to promote evasion of tumor immunity by promoting apoptosis of activated effector T-cells [18] and tumor resistance to Tcell mediated lysis [93]. In preclinical studies, blockade of B7-H1 with a specific monoclonal antibody has resulted in enhanced antitumor immune responses [93,94]. B7-H4 is another member of the B7 family that has been implicated as a negative regulator of T-cell immunity [95]. It has been demonstrated that B7-H4 can inhibit T-cell proliferation and IL-2 production, and that blockade of B7-H4 in preclinical animal models results in enhanced cytotoxic T-cell responses against an alloantigen [19]. The expression of B7-H4 has been observed in many types of human cancer, such as breast [96], ovary [97], and lung [98]. In renal cell carcinoma, its expression has been correlated with more aggressive tumors, particularly in those cases where both B7-H1 and B7-H4 are aberrantly overexpressed [99]. Therefore, blocking of molecules such as B7-H1 and B7-H4 expressed on tumor cells can reduce coinhibitory signals directly at the site of the tumor (Table 3), resulting in enhanced antitumor immune responses.
A different strategy involves blocking of inhibitory molecules directly expressed on T-cells. An example is CTLA-4, a negative regulator of T-cell activation, which is expressed on the T-cells and, like its homolog CD28, binds to B7 on the surface of the APC. Binding of CTLA-4 to B7 initiates a negative signal cascade that leads to downregulation of the T-cell response [100,101]. The blockade of CTLA-4 with specific, monoclonal antibodies (mAb) has been explored as a monotherapy or in combination with vaccine therapy in preclinical and clinical studies. In preclinical studies, the use of antiCTLA-4 mAb as a monotherapy has shown antitumor activity with immunogenic tumors [100,101], but not with poorly immunogenic tumors, such as MC38 [102]. In combination with vaccines, antiCTLA-4 mAb has been used to enhance antitumor T-cell responses elicited by the vaccine, thus resulting in effective antitumor effects [102]. In the clinic, antiCTLA-4 has been used also as a monotherapy or in combination with other immune-mediated anticancer modalities [103]. Results from a phase I clinical trial with antiCTLA-4 mAb (ipilimumab) in patients with metastatic melanoma or renal cell cancer recently reported a 14% response rate and multiple, and at times severe, immunemediated toxicities such as nephritis, panhypophysitis, and enterocolitis, among others [104,105], this last point constituting a potential disadvantage of the approach.
Depletion/Inhibition of Regulatory T-Cells
Naturally occurring regulatory T (Treg) cells, characterized by expression of IL-2R alpha, the transcription factor Foxp3, CTLA-4, and glucocorticoid-induced tumor necrosis factor (TNF) receptor (GITR), constitute 5% to 10% of peripheral CD4 + T-cells [11,106]. Treg cells represent an important mechanism of peripheral T-cell tolerance through their inhibition of self-reactive effector T-cells [107], and have also been implicated in the lack of effective antitumor immunity as the number of Treg cells are increased in the tumors and peripheral blood of cancer patients [108,109]. Previous studies in several models of mouse tumors have demonstrated that deletion of Treg cells by using an antiCD25 mAb enhanced the development of antitumor immunity leading to tumor rejection [110,111]. Furthermore, it has been previously shown that antigen-specific T-cell responses induced by poxviral vaccines can be augmented by simultaneous administration of antiCD25 mAb in mice [112]. Among alternative modalities that can be used in humans to delete Treg cells is denileukin diftitox, (DAB 389 IL-2), a fusion protein of IL-2 and diphtheria toxin, previously shown in mouse preclinical studies to reduce Treg cells and to enhance antigen-specific immune responses induced by poxviral vaccines [113]. A potential drawback of both approaches is that activated, effector T-cells also transiently upregulate the expression of CD25 on their cell surface, therefore being at risk of depletion by strategies that target CD25. In the clinic, denileukin diftitox was previously shown to reduce Treg cells and to lead to objective clinical responses in patients with ovarian cancer [12,114]. Moreover, antitumor immunotherapy approaches combining denileukin diftitoxmediated deletion of Treg cells followed by vaccination with RNA-transfected DCs, tumor antigen peptides, or DCs modified by infection with rF-CEA(6D)/TRICOM, have been shown to improve tumor-specific T-cell responses in patients with renal cell cancer, melanoma, or CEA-positive malignancies, respectively, [115][116][117].
Inhibition of Immunosuppressive Cytokines
Tumors can also evade immunosurveillance by directly secreting a number of inhibitory cytokines or by inducing various types of immune cells to secrete cytokines associated with reduced immune responses. One of these cytokines is the transforming growth factor beta (TGF-β), which can be directly secreted by many types of tumor cells, including breast, prostate, colon, liver, lung, and melanomas, among others [118,119]. TGF-β exerts its negative effects on T-cells, NK cells, macrophages and DCs [120]. Several preclinical studies have demonstrated that blockade of TGFβ can reverse the immunosuppressive effects of the tumor microenvironment. For example, a small molecule TGF-β inhibitor was used in a mouse tumor model to rescue the functionality of infiltrating CD8+ T-cells (TILs), which are usually hyporesponsive [121]. Recently, it was also reported a synergistic improvement of a peptide vaccine modality in combination with a monoclonal antibody against TGF-β, in a murine tumor model [122]. Although no adverse effects have been observed in studies so far conducted, the dual role of TGF-β on normal versus tumor cells, where it can function as a suppressor or promoter of tumor development, respectively, may constitute a potential problem for this approach and indicates the necessity for detailed studies aimed at optimizing the use of antiTGF-β reagents while minimizing the potential for adverse effects.
Another cytokine that has a negative impact on the development of antitumor T-cell responses is the vascularendothelial growth factor (VEGF). A major role of VEGF is to induce the process designated as tumor angiogenesis, which involves the development of an adequate tumor vasculature that will support a blood supply to the growing tumor [123,124]. Additionally, VEGF contributes to tumor immune escape by inducing the development of immune cell populations with immunosuppressive functions, like immature DCs [24] and the recruitment of tumor-associated macrophages (TAM) to the tumor stroma [13,14,125]. Strategies aimed at inhibiting VEGF or its receptors, therefore, will not only disrupt the tumor vasculature thus impairing tumor growth, but will also improve antitumor immunity by eliminating inhibitory cell populations, resulting in enhanced responses to cancer vaccines. In preclinical studies, for example, an antiVEGF antibody enhanced the efficacy of a peptide-pulsed DC-based vaccine that resulted in prolonged and pronounced antitumor effect [126]. Therefore, inhibition of VEGF may be a valuable adjuvant in the immunotherapy of cancer. A disadvantage of antiVEGF therapies in the clinic has been the emergence of toxicities that included wound healing complications as well as adverse vascular effects.
Conclusions
Progress in understanding the molecular mechanisms that govern immune activation as well as the mechanisms used by tumor cells to evade surveillance by the immune system are advancing the development of immune-mediated therapies that could be effectively used against a range of human cancers. The combination of cancer vaccines with other therapeutical modalities, in particular established therapies such as radiation and chemotherapy, as well as small molecule targeted therapies, provides an opportunity to further improve the outcome of vaccine interventions against cancer. Moreover, several studies also indicated that patients who receive a cancer vaccine have an enhanced outcome to subsequent therapies, thus providing another possible approach for the use of cancer vaccines prior to other cancer interventions. A prospective randomized trial is being initiated to substantiate these findings. Unlike other modalities, cancer vaccines have so far demonstrated no associated toxicities and therefore their use could not only result in improved patient survival but also in improvements in quality of life.
Figure 1 :
1Cancer vaccine strategies aimed at shifting the immune environment of a tumor from protumorigenic to antitumorigenic.
Figure 2 :
2The epithelial-to-mesenchymal transition (EMT) in tumor progression: an opportunity to target metastatic tumor cells. The epithelial-to-mesenchymal transition (EMT) and its reverse process, designated as mesenchymal-to-epithelial transition (MET), are involved in the progression of epithelial tumors towards metastasis. Vaccine strategies targeting molecules that control the EMT process, for example, the transcription factor Brachyury, could be used to block tumor spreading.
Table 1 :
1Vaccine-delivery systems.Vaccine-delivery systems
Immunization against multiple
antigens *
Immunization against
specified antigen(s)
Cell-based
Cell-based
Autologous whole-tumor cells
DCs pulsed with peptide
Allogeneic whole-tumor cells
Genetically-modified DCs
Genetically-modified tumor cells
DCs-tumor fusion
Protein/Peptide based
DCs loaded with tumor lysate
Protein
Peptide
Agonist peptide
Antiidiotype MAb
Mab fusion proteins
DCs transfected with
tumor-derived RNA
Protein/Peptide based
Tumor lysates
Vector-based
Heat shock proteins-tumor peptides Plasmid DNA
Bacterial vectors
Listeria
Salmonella
Yeast vectors
Viral vectors
Adenovirus
Vaccinia
Avipox (fowlpox)
MVA
* Vaccine formulation includes known and unknown antigens.
Table 2 :
2Human carcinoma antigens.Carcinoma antigens *
Tumor-specific antigens
Tumor-associated antigens
Mutated molecules
Carcinoembryonic antigen (CEA)
K-RAS
Mucin 1 (MUC-1)
p53
Prostate-specific antigen (PSA)
Fusion molecules
Prostate acid phosphatase (PAP)
BCR-ABL
Prostate stem-cell antigen (PSCA)
Brachyury
Virally-derived molecules
TERT
HPV-16 E6, E7
Wilm's tumor 1 (WT1)
EBNA1, LMP1 and LMP2
Her-2/neu
Sox-2
NY-ESO-1
Cyclin D1
Mesothelin
Survivin
* Included is only a partial list of antigens for human carcinomas.
Table 3 :
3Strategies to enhance antitumor T-cell responses * .Strategy
Use of costimulation in vaccine formulation
Cytokines
Effect on APC (GM-CSF)
Effect on T-cells (IL-2, IL-7, IL-15, IL-12)
Radiation
Chemotherapy
Small molecule targeted therapies
Inhibition of coinhibitory signals
At the tumor site (B7-H1, B7-H4)
Directly on T-cells (CTLA-4)
Depletion/inhibition of Treg cells
Inhibition of immunosuppressive cytokines
AntiTGF-β
AntiVEGF
* Only a partial list is included here.
AcknowledgmentThe authors thank Debra Weingarten for editorial assistance in the preparation of this manuscript.
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| 1,999,770 | BACKGROUND ::: The aim of this study was to analyze the spatial distribution and proliferation of adoptively transferred CD8+ T-lymphocytes sensitized against allogeneic tumors. ::: ::: ::: MATERIALS AND METHODS ::: Transgenic β-actin-luc mice that express luciferase were sensitized against allogeneic SL2 lymphoma. CD8+ T-lymphocytes from these mice were transferred to lymphocyte-deficient, recombination activating gene-deficient (Rag-/-) mice bearing SL2 tumors and were tracked using bioluminescence imaging. ::: ::: ::: RESULTS ::: Two out of six Rag-/- mice rejected their tumors. There were no apparent differences in spatial distribution and proliferative intensity of adoptively-transferred CD8+ T-lymphocytes between the two Rag-/- mice that rejected allogeneic SL2 tumors and the four Rag-/- mice that did not. ::: ::: ::: CONCLUSION ::: The pattern of distribution in the mouse body and proliferative intensity of CD8+ T-lymphocytes do not seem to be decisive factors influencing allogeneic tumor rejection. | Transplantable murine tumors release mouse-tropic and xenotropic type- -c viruses. | Our newly generated murine tumor dendritic cell (MuTuDC) lines, generated from tumors developing in transgenic mice expressing the simian virus 40 large T antigen (SV40LgT) and GFP under the DC specific promoter CD11c, reproduce the phenotypic and functional properties of splenic wild type CD8α + conventional DCs. They have an immature phenotype with low co-stimulation molecule expression (CD40, CD70, CD80, and CD86) that is upregulated after activation with toll-like receptor ligands. We observed that after transfer into syngeneic C57BL/6 mice, MuTuDC lines were quickly rejected.Tumors grew efficiently in large T transgene-tolerant mice. To investigate the immune response toward the large T antigen that leads to rejection of the MuTuDC lines, they were genetically engineered by lentiviral transduction to express luciferase and tested for the induction of DC tumors after adoptive transfer in various gene deficient recipient mice. Here, we document that the MuTuDC line was rejected in C57BL/6 mice by a CD4 T cell help-independent, perforinmediated CD8 T cell response to the SV40LgT without pre-activation or co-injection of adjuvants. Using depleting anti-CD8β antibodies, we were able to induce efficient tumor growth in C57BL/6 mice. These results are important for researchers who want to use the MuTuDC lines for in vivo studies. | Different responses of lymphoid cells from tumor-bearing as compared to tumor-immunized mice when sensitized to tumor specific antigens in vitro. | A leukocyte adherence inhibition (LAI) assay of anti-tumor immunity in rats using selective radioimmunological assessment of adherence of T lymphocytes and monocytes. | Immune response in lung cancer mouse model mimics human anti-Hu reactivity | Previous work has shown that a cytotoxic T lymphocyte (CTL) immune response of syngeneic mice immunized with a chemically-induced BALB/c (H-2d) fibrosarcoma was directed against an individual tumour-associated antigen. To see whether this reaction was restricted by products of the major histocompatibility complex (MHC), anti-H-2 alloantisera to K or D antigens were used to interfere with the CTL-mediated immune response. Antisera to Kd but not to Dd antigens inhibited the lytic activity of CTL against fibrosarcoma cells. In addition, the study of the CTL response in F1 leads to P antitumour immunized chimeric mice showed that antitumour cytotoxicity developed only when F1 and parental host shared the Kd region. Both experiments strongly indicate that recognition of the individual tumour-associated antigen of the BALB/c fibrosarcoma is restricted by the products of H-2Kd genes. | Prevention of ultraviolet radiation- or chemical carcinogen-induced morphologic transformation and inhibition of tumor-producing transformed cell growth by lymphotoxin and by normal spleen leukocytes were quantitatively compared to define the antineoplastic activity spectra of these natural immune mediators. When Syrian golden hamster embryo cells seeded for colony formation in culture dishes were treated simultaneously with carcinogen and lymphotoxin, the number of morphologically transformed cell colonies was irreversibly reduced by 50% in the presence of 6 units of lymphotoxin/ml. Lymphotoxin inhibition of tumor cell growth, however, was reversible and 50% reduction in tumor cell growth in three transformed lines required 124, 330, and 477 units/ml. Thus, the anticarcinogenic activity of lymphotoxin can be 20-fold or more greater than its tumor growth-inhibitory activity. Similarly spleen leukocytes also were more effective as an anticarcinogen than as an inhibitor of tumor cell growth, consistent with previous observations that naturally occurring spleen leukocyte antineoplastic activity may result from lymphotoxin secretion. | L5178Y leukemia cells, syngeneic in DBA/2 mice, in which they produce a lethal ascites tumor from a single cell, contain a specific antigen which is revealed by immunization with irradiated cells. In DBA/2 animals bearing the tumor this can be eradicated by injection of spleen cells, obtained from allogeneic mice that had been immunized by a single injection with L5178Y cells, at a ratio of 200 spleen cells per L5178Y cell present. Serum as well as spleen cells, was effective if the donor animals were hyperimmunized with the leukemia cells. Spleen cells from allogeneic animals hyperimmunized with normal DBA/2 spleen cells were relatively ineffective against the tumor in vivo , but showed activity when tested against L5178Y cells growing in tissue culture. In vitro studies involving selective neutralization indicate that the antitumor effect of spleen cells from allogeneic mice immunized with L5178Y cells is brought about mainly by a selective reaction against the tumor directed against the tumorspecific antigen. Immune processes directed against the normal DBA/2 transplantation antigens have little effect against the tumor in vivo , but prevent the growth of the lymphoma cells in vitro . Quantitative considerations limit this method of treatment to animals containing between 104 and 105 tumor cells. |
1,999,771 | The International Shooting Sport Federation still administers Olympic and non-Olympic rifle , pistol , shotgun , and running target shooting competitions , although there is also a large number of national and international shooting sports controlled by unrelated organizations . | of the XXIX Olympiad was awarded on August 9 to Katerina Emmons, a Czech shooter competing in the 10 m Air Rifle Women event. International Shooting Sport Federation The International Shooting Sport Federation, also known with the acronym ISSF, is the governing body of the Olympic Shooting events in Rifle, Pistol and Shotgun disciplines, and of several non-Olympic Shooting sport events. ISSF’s activities include regulation of the sport, Olympic qualifications and organization of international competitions such as the ISSF World Cup Series, the ISSF World Cup Finals, the ISSF Separate World Championship in Shotgun events and the ISSF World Championship | USA Shooting USA Shooting, a 501(c)(3) non-profit corporation, was chartered by the United States Olympic Committee as the National Governing Body (NGB) for the sport of shooting in April 1995. The NRA had served as the NGB for one hundred years prior to this change in administration. It is USA Shooting's mission to prepare American athletes to win Olympic medals, promote the shooting sports throughout the U.S., and govern the conduct of international shooting in the country. The organization implements and manages development programs and sanctions events at the local, state, regional, and national levels. Prior to 1979, a year-round | An analysis of the how and why international sports federations require changes to host nations laws and in particular their focus on requiring commercial protections over human rights protections | World Baseball Softball Confederation (WBSC; ) is the world governing body for the sports of baseball, softball, and Baseball5. It was established in 2013 by the merger of the International Baseball Federation (IBAF) and International Softball Federation (ISF), the former world governing bodies for baseball and softball, respectively. Under WBSC's organizational structure, IBAF and ISF now serve as the Baseball Division and Softball Division of WBSC. Each division is governed by an executive committee, while the WBSC is governed by an executive board.
Headquartered in Pully, Switzerland, the WBSC was granted recognition as the sole competent global authority for both the sports of baseball and softball by the International Olympic Committee at the 125th IOC Session on 8 September 2013.
The WBSC has 208 National Federation Members in 141 countries and territories across Asia, Africa, Americas, Europe and Oceania. Professional baseball organizations as well as youth organizations are also included and form an arm of the WBSC as associate members.
As the recognised governing body in baseball/softball/Baseball5, the WBSC is charged with overseeing all international competitions and holds the exclusive rights of all competitions, tournaments and world championships featuring National Teams. These rights extend to the Olympic Games. WBSC's members hold the rights to organize and select National Teams. This exclusive authority of the WBSC and its members in each constituent country to sanction and regulate the sport of baseball applies in the 141 territories in which the WBSC has an associated National Federation.
Discussions to merge the two separate world governing bodies for the sports of baseball and softball were sparked by a Memorandum of Understanding that saw baseball and softball leaders agree to form a joint bid to be added to the 2020 Olympic Games sports program. Baseball and softball were dropped from the 2012 Summer Olympic program and were scheduled to be reinstated for the 2020 Olympics, but the 2020 Olympics were delayed due to the COVID-19 international pandemic. In August 2021, the International Olympic Committee announced that softball would not be part of the 2024 Paris Olympics. Baseball5 is still set to feature in the 2026 Youth Olympics.
History
Following its exclusion of baseball and softball from the Summer Olympics in 2005, the IOC reclassified baseball and softball as two disciplines of the same sport. As the IOC's guidance indicated the necessity for baseball and softball to be jointly considered for reinstatement in the Olympic programme, the two independent International Federations set out on a path toward a full and complete merger.
In 2012, the International Baseball Federation (IBAF) and the International Softball Federation (ISF) laid out the essential ground rules for partnership and began working on a constitution that would guide the merger and provide a framework for governance, ethics and operations. At a historic IBAF Congress in Tokyo in April 2013, the Constitution was ratified and since it had already been approved by an ISF working group empowered to do so, the WBSC was officially formalized and empowered.
The creation of a single federation allowed for the permanent alignment, merger and management of baseball and softball at the world level. The merger resulted in an immediate boost to the governance, universality and gender equality of baseball and softball, criteria for an Olympic sport that are heavily valued by the IOC.
At the first-ever World Baseball Softball Congress—in Hammamet, Tunisia—Italy's Fraccari was elected to a seven-year term as the first president of WBSC, along with a fully elected Executive Board.
Creation of Baseball5
In 2018, the WBSC introduced a third discipline to be played at an international level, Baseball5 (B5), which is a five-on-five, five-inning game designed to be played with only a rubber ball on a small field, and which is targeted at underserved communities, as well as offering a low-cost and fast-paced entry point to baseball and softball in new places around the world. The WBSC introduced it to aid its ultimate goal of having a billion-strong baseball-softball community by 2030. A major difference between B5 and baseball/softball is that the game is played without a pitcher, with the batter starting each play with the ball. It was inspired by various Latin American street games, such as "cuatro esquinas" (four corners) in Cuba, and has been played in some international tournaments in the Americas and Europe, as well as having been implemented in some schools in various countries. It is due to feature in the 2026 Youth Olympic Games, and has two World Cups for youth and senior players alternating each year starting in 2022, with both of these international events being played in a mixed-gender format. The WBSC is also planning to, as part of its general push into E-Sports, introduce a video game version of Baseball5 in the near future.
Organizational structure
The WBSC is governed by the executive board, which consists of fourteen members: president, secretary general, two vice presidents, baseball executive vice president, softball executive vice president, treasurer, four members at large, athlete representative for baseball, athlete representative for softball, and global ambassador.
The Baseball Division is governed by an executive committee, which has thirteen members: president, secretary general, 2nd vice president, 3rd vice president, treasurer, three members at large, four continental vice presidents (one each for Africa, Americas, Europe, and Oceania), and executive director.
The Softball Division is governed by an executive committee that has twenty-three members: president, secretary general, 1st vice president, 2nd vice president, treasurer, twelve vice presidents (two each for Africa, Asia, Europe, Latin America, and Oceania, and one each for North America and English-speaking Caribbean), two at-large members, two athlete representatives, immediate past president, and executive director.
The WBSC has four departments: media, finance, tournaments, and marketing. It also has several commissions.
Continental Confederation Members and Leagues
There are six confederation members in the WBSC divided by geographical regions: Africa, Americas, Asia, Europe, and Oceania. In total, there are 198 countries affiliated with the WBSC. By region, there are 28 members in Africa, 58 members in the Americas, 34 members in Asia, 54 members in Europe, and 24 members in Oceania.
Unlike the ICC, the WBSC identifies associate members as those who particularly endorse international baseball and softball with their own leagues in partnership with the WBSC. These leagues support baseball and softball to the extent that they are major sports in their respective countries. The table below has all leagues along with the country hosted:
International Tournaments
Men's baseball
Women's baseball
Baseball5
Baseball5 tournaments are mixed-gender, with each team of five active players required to field at least two active players per gender at all times.
Men's softball
Women's softball
Rankings
Men's baseball
The following table has the Top 20 men's baseball countries in the world. The Top 20 is here due to the next iteration of the World Baseball Classic, the world's major tournament in men's baseball, anticipating to have 20 countries compete. As such, this table shows the projected teams in the next WBC based on the ranking's algorithm.
Women's softball
The following table has the Top 16 women's softball countries in the world. The Top 16 is here due to the next iteration of the Women's Softball World Championship, the world's major tournament in women's softball, anticipating to have 16 countries compete. As such, this table shows the projected teams in the next WSWC based on the ranking's algorithm.
See also
Baseball awards#International
Softball at the Summer Olympics
Baseball at the Summer Olympics
References
External links
Baseball in Switzerland
Bas
International sports organizations
Baseball
Organisations based in Lausanne
Softball in Switzerland
Softball organizations
Sports organizations established in 2013
World Baseball Classic | International Practical Shooting Confederation The International Practical Shooting Confederation (IPSC) is the world's second largest shooting sport association and the largest and oldest within practical shooting. Founded in 1976, the IPSC nowadays affiliates over 100 regions from Africa, Americas, Asia, Europe and Oceania. Competitions are held with pistol, revolver, rifle and shotgun, and competitors are divided into different divisions based on firearm and equipment features. While everyone in a division competes in the Overall category, there are also own separate awards for the categories Lady (female competitors), Junior (under 18 years), Senior (over 50 years) and Super Senior (over 60 | Organisation of sport in Australia Institute System Intergovernmental Agreement" provides "guidance on how the sector will operate, with a principal focus on the delivery of the high performance plans of national sporting organisations." Australian Government provided small amounts of funding in the 1950s and 1960s through the support of the National Fitness Council and international sporting teams such as the Australian Olympic team. The Australian Government's serious involvement and investment into sport came with it establishing the Australian Institute of Sport (AIS) in 1981. AIS was set up to improve Australia's performances in international sport which had started to decline in the 1960s and 1970s | Organisation of sport in Australia Institute System Intergovernmental Agreement" provides "guidance on how the sector will operate, with a principal focus on the delivery of the high performance plans of national sporting organisations." Australian Government provided small amounts of funding in the 1950s and 1960s through the support of the National Fitness Council and international sporting teams such as the Australian Olympic team. The Australian Government's serious involvement and investment into sport came with it establishing the Australian Institute of Sport (AIS) in 1981. AIS was set up to improve Australia's performances in international sport which had started to decline in the 1960s and 1970s | Olympic sports program of future Games, through a recommendation by the IOC Olympic Programme Commission, followed by a decision of the IOC Executive Board and a vote of the IOC Session. When Olympic demonstration sports were allowed, a sport usually appeared as such before being officially admitted. An International Sport Federation (IF) is responsible for ensuring that the sport's activities follow the Olympic Charter. When a sport is recognized the IF become an official Olympic sport federation and can assemble with other Olympic IFs in the Association of Summer Olympic International Federations (ASOIF, for summer sports contested in the Olympic Games), Association | 1,999,771 | The International Shooting Sport Federation is in charge of Olympic and non-Olympic rifle , pistol and shotgun competitions . | what is the name of the international shooting sport federation, the governing body of olymp | who introduced the olympic shooting world cup format | what is the abbreviation for international association of athletics federations | Beyond the Acronyms: Sport Diplomacy and the Classification of the International Olympic Committee | When was shot put made an olympic sport? | when was the international federation for equestrian sports established | who manages the domestic olympic program in the united states | when did the first practical shooting competition take place |
1,999,772 | Establishment and Identification of Electrical Load Simulator System Model | Real-time simulation model for governor of pumped storage power unit(PSPU) is established by using toolbox of MATLAB,such as Simulink,RTW and xPC Target,etc.The real-time simulation model and a governor of PSPU are connected with input-output interface circuits to constitute a semi-physical real-time simulation system.Tests are carried out for verification with the parameters of a real PSPU.Test results show that the real-time simulation system has advantages such as: conveniently modeling,automatically generating effective simulation program,flexibly adjusting parameters,and test curves greatly coincide with these of prototype test.This simulation system can be served as a test platform in the design stage of governors,and as a test system of PSPU dynamic characteristics in acceptance test stage. | Dynamic simulation is a valuable tool for optimizing the design and operation of steam electric power plants, especially those that change load or shut down frequently. However, its use has been limited because it has required experienced modeling specialists. An easy-to-use modeling system has therefore been developed under Electric Power Research Institute sponsorship. It has been tested by simulating transients performed on Boston Edison Company's Mystic Unit 7, a 550-MW oil-fired plant, with good agreement between the simulations and the recorded plant transients. | Production Simulation for Power System Studies | Lesson Learned from Power System Design with PowerWorld Simulator | Technological innovations in electrical systems require the development of testing and validation tools that provide a safe environment and allow configuring different operating conditions. In this regard, power hardware-in-the-loop (PHIL) simulation is a suitable tool that interacts with physical components knowing as hardware under test (HuT) according to a mathematical model. In this work, a PHIL simulation for both electrical source analysis and load studies as HuT using linear and nonlinear loads is carried out. It is performed by means of an ideal transformer model (ITM) as interface algorithm along with a feedback stage using digital filtering, where a state-space control is simulated and implemented in a real-time hardware and a voltage source inverter (VSI) is used as a power amplifier. Different loads are used to validate the PHIL implementation such as resistive load, resistive-inductive load, and a nonlinear load by considering a dc motor. In this work, two HuT are used, a transformer arrangement and a power inverter. | The HCPS group of Electrical Power Engineering department has a Real-Time Digital Simulator (RTDS) for the study and analysis of power system phenomena. RTDS helps to perform real-time simulations that allow the user to interact with the grid model in real time. During this Master thesis work the existing Noord-Holland grid is implemented in RTDS. This model is verified by other software models of the Noord-Holland grid. The existing grid model is expanded with a large wind power plant. Subsequently the dynamic behaviour of the grid with large wind power input is investigated. For future works this model can be used as a test grid. | Load modeling by means of static voltage characteristics is a modern way to describe mode parameters influence on it. Nowadays typical curves are used, which leads to inaccuracy growth in case of networks with complex load buses. Consequently, it is appropriate to apply real characteristics with compensating devices taken into account. Also the preliminary math modeling is needed to estimate experimental data reliability and make a model form hypothesis. | Experimentally obtained ZIP load models are used for the power system analysis. Estimating accuracy of such models is presented in this paper. The dependence of ZIP load model error on the range in which voltage changes during the experiment, the number of measured values of voltage and power, standard deviation of the load change random process have been obtained using the computing experiment. The results could be used to estimate the accuracy of ZIP load models or to design the experiment to determine ZIP load models with prescribed accuracy. | 1,999,772 | The mathematical model of an electrical load simulator is built by using mechanism modeling method firstly,taken the electrical load simulator drived by PMSM directly as research object.The frequency response characteristic of the key block in the system model is tested through experimental methods,which verifies the modeling process is correct.This work has laid the basis for the further study. | Application of simulation technology to design of power plant | In this work, we propose a new modeling methodology for simulation of power distribution systems at the package level of high performance devices (e.g. microprocessor). The methodology combines the power of the numerical modeling tools with the simplicity and speed of the TLM method. To capture non-ideal features such as cutouts in the ground planes, the electrical properties of the cells are derived and described in software models by full wave modeling. By cascading these cells, the entire plane can be formed for software modeling. In this paper, the scattering parameter data method is explored, where Ansoft's High Frequency Structure Simulator (HFSS) is used to characterize the cells and Agilent's Advanced Design System (ADS) is used for the circuit level simulation. The accuracy of the models and validity of the methodology has been verified through high frequency measurements on a real microprocessor package. Measurements were done as a one port device. Good correlations between the simulation and the measurements have been obtained. | Simulation Features of Electric Circuits with Components Described by Discrete Parameters | Development of Power Plant Simulation Technology | Application and Comparison of MC Method and QA Method on Simulation of Communication System | The Simulation and Analysis of the Circuit Operation of Power System with MATLAB | Investigation of behavioral model accuracy using a state-space and convolution-based transient simulator | This paper presents three IEEE standardized power system benchmarks developed in SimPowerSystems, a MATLAB/Simulink package. The simulation models can be used for baselining and testing new control techniques and protection algorithms for renewable and micro grids integration studies. Analytical examples as well as static, time domain, and frequency analysis are presented to support the correctness of the implementation. The models are available in MATLAB-Central file exchange for power system education and research worldwide. |
1,999,773 | Eggs clip through to bottom of map after being dug out of nest | The eggs will always stick to the edges of the rings. It is very hard to extract the egg with it's normal shape. | Just carry their egg from their sleeping area , no need to move in the map. They will come for it. Just learned this while farming azure Rath. Dont know if it works with other monster though. Also help when you want to keep them in that area. They are leaving sleeping place? Just pick egg and he/she will come back | Egg (band) Egg were an English progressive rock band formed in January 1969. The founding members of Egg were Dave Stewart who played organ, Mont Campbell on bass and vocals, and drummer Clive Brooks. The band was formed of former members of Uriel, the other member of which was guitarist Steve Hillage. After Hillage left Uriel in August 1968, the other three continued as a trio. Having signed a deal with the Middle Earth club's management branch, they were advised to change their name to Egg, allegedly because Uriel "sounded too much like 'urinal'". In mid-1969 the band signed a | Our love birds laid their eggs in a not very secure location, and I wanted to know if we could just move the eggs into their nest box. | Also, use older eggs if you can. Newer eggs are harder to peel due to the moisture and gases trapped underneath the surface. | Do cockateils egg tooths fall off? | Hello, I knew she was getting ready to lay soon and today we found this on the ground by the run pen.
It's her first egg and I do believe that we've got a worm problem.
Can someone confirm by looking at the images brown egg]( and [another view same egg
I can lace everyone's feed with DE but IF these are roundworms than I'll have to nuke the flock. Any recommendations? | How alligators lay eggs? | 1,999,773 | Granted, this really only happens in 1 out of 50 game sessions, but it happened the other day on a haz3 complexity3 mission in of those ridiculously fun chimney caverns.
I had to worker my driller up into the guts of the roof of the map. I worked my way into the nest and hacked the eggs free. It popped out in the typical way but then disappeared in an instant. I found it a few seconds later on the map pda sitting a couple hundred meters below me. A long fall, and some red sugar to reach me out of Iron Will, and I was able to get on with it.
Thus is an infrequent occurrence, and it *only* happens with eggs, in my experience.
Is there a fix for this? It's been happening since i picked up the game on last New Year's Eve. | Egg cracked, Who can I speak to? | Egg Hunt Oddness (spoiler?) | [Question] Sudden egg intolerance? | (Masterwork) Egg Laying Bug? | why do orbicella eggs break apart when they reach the water | egg incubation glitch, "hatch this egg by feeding it butter"...? | what disease causes egg drop in ducks | Bug where completed contracts re-appear and resets the Prophecy Egg |
1,999,774 | PSA: Tahm Kench works really well with Zeke's | I currently have 1.03 and 1.06, is that too much for Zeke? Or one of those picks and some other assets. | Zeke's suspension, as it currently stands, will leave him out until week 16, which is most leagues' championship week. Is he worth a hold to get one game out of him? Obviously that depends on whether your team has a chance at the championship, and whether you are willing to allow another owner to stash him away.
Zeke's appeal is set for Dec. 1, which means he may only miss 4 games. If he wins, he'll be back for the fantasy playoffs. However, he already appealed his suspension once, and lost.
So, is he droppable for teams that need to win now? For teams willing to burn a bench spot: is David Johnson or Josh Gordon a better stash, if available?
What are *you* doing with Ezekiel Elliott? | **Passive:**
Tahm Kench's basic attacks deal 4% of Tahm Kench's maximum health as bonus magic damage and apply a stack of An Acquired Taste to enemy champions for 5 seconds (stacks 3 times).
Against enemies with three stacks, his Tongue Lash is enhanced.
**Q - Tongue Lash**
**Range:** 900
**Cooldown:** 5
**Cost:** 50
Tahm Kench roots himself briefly while launching his tongue in a target direction. Tongue Lash stops once it hits a target, dealing 80 / 130 / 180 / 230 / 280 (+70% of ability power) magic damage, slowing whatever he hits by 30 / 40 / 50 / 60 / 70% for 3 seconds, and applying a stack of An Acquired Taste.
If Tahm Kench slathers an enemy champion with three stacks of An Acquired Taste and then hits them with Tongue Lash, he consumes the stacks to stun them for 2 seconds instead.
**W - Dark Water**
**Cooldown:** 20
**Cost:** 100
Tahm Kench dives underwater, becoming untargetable for 1 / 1.5 / 2 / 2.5 / 3 seconds. Anytime during the duration Tahm Kench may end reactivate the ability to resurface early. When Tahm Kench surfaces he knocks nearby enemy units airborne for .5 seconds, knocking them away slightly and dealing 10 / 20 / 30 / 40 / 50 damage (+50% of ability power).
**E - Thick Skin**
**Cooldown:** 3
*Passive:* 80/85/90/95/100% of damage Tahm Kench takes is turned into grey health. Once he leaves combat, the grey health falls off, healing him for 30-100% of the amount of grey health he has earned (depending on level). This passive is unavailable while Thick Skin is on cooldown.
*Active:* Tahm Kench converts his grey health into a shield that lasts 3 seconds.
Thick Skin's cooldown starts when the shield expires or is broken.
**R - Abyssal Voyage**
**Range:** 250
**Cooldown:** 120 / 90 / 60
Tahm Kench swallows a nearby targeted champion, placing them in stasis for 4 seconds. After 1 second, Tahm Kench gains the ability to recast Devour, spitting out the swallowed target.
If the target is an enemy champion, they take 60 / 105 / 150 / 195 / 240 (+11% (+2% per 100 AP) of target's maximum health) magic damage.
If Tahm Kench swallows an allied champion OR enemy champion with three stacks of An Acquired Taste, he gains the ability to cast W - Dark Waters, taking that champion with him. | I really like this kid. If we miss out on Gordon and Gurley, J-Train would be my next top choice. Dreads aside, he reminds me of Marshawn. He's got great break tackle ability, good speed, and he's built almost exactly like Marshawn:
Marshawn - 5'11, 215lbs.
Jay Ajayi - 6'0, 216 lbs.
Don't get me wrong, I'm not saying Jay is definitely the next Marshawn here, but he looks and runs very similarly. I realize Boise State doesn't face elite competition or anything, but his talent is obvious. I like this kid's fire, his size, his talent, and I would be very happy if he became a Seahawk.
| I’m just curious on people’s first thoughts on the new Zeke card and how he falls in with the rest of the runningbacks. I’m thinking about going for him tomorrow because of the abilities honestly. | Very hard pick, especially between Gates and Gonzalez. Both have been great blockers and reliable targets forever. Maybe Tony Gonzalez has been more important to the Chiefs than Gates has been to the Chargers. | No commentary on NFL network yet, they are still gushing over the German WR the Vikings took. Will update if Mayock mentions anything.
Edit: Mayock ain't saying shit so here's his NFL.com draft profile.
OVERVIEW
Houston-Carson's 2014 season ended early due to injury (67 tackles, three interceptions in nine games), but he returned to form in 2015 -- winning consensus All-American honors at free safety after starting for three years at cornerback. He has prototypical size and plenty of speed to make plays in the deep secondary, intercepting four passes, returning one for a 94-yard score in 2015. Houston-Carson also possesses secure tackling skills which helped him lead the team with 109 stops on the year (4.5 for loss). "DHC" started as a redshirt freshman (55 tackles, one interceptions, seven pass breakups) and sophomore (62 tackles, 4.5 TFL, 2 INT, 11 PBU), too. Houston-Carson also presents special-teams prowess, with nine career blocked kicks and working as a gunner on coverage units.
ANALYSIS
STRENGTHS Team captain. Combines a nose for the ball and a hot motor to fill up stat sheet. Slippery on his way to the ball with ability to weave through traffic and slip blocks. Plays with plus balance and is able to withstand contact from blocker and stay in the play. High-end, charged up tackler with some explosion behind his pads a high-end tackle production. Former cornerback with a background in man coverage. Has twitch and acceleration to match slot receivers out of their breaks. Plays with outstanding awareness of man and ball in zone coverage. Snared seven interceptions over last two years. Special teams gunner and overall ace with multiple coverage tackles. Gets out of his stance in a flash and has unique talent for blocking kicks including four punts in nine games in 2014.
WEAKNESSES Top-end speed to recover and drive from the hash towards the deep sideline is just average. Pad level can get too high robbing him of "stop now" tackle strength against running backs. Gets himself in trouble with some of his angles to the ball. Will take direct angles in his chase leaving little margin for error. Former cornerback still learning proper leverage as a run supporter at safety. Must learn to balance natural aggressiveness with necessary caution. Tapered frame may not be able to add much more weight.
DRAFT PROJECTION Rounds 4 or 5
NFL COMPARISON Husain Abdullah
BOTTOM LINE Houston-Carson exudes confidence and football intelligence on the field and plays with the swagger of a D-1 safety. In coverage, he is instinctive and responsive and trusts his eyes. While he is a ready, aggressive tackler, he still needs more beef on his frame and has to fine tune his angles to the ball to eliminate some of the big plays he has had a hand in. His physical and mental tools are starter's quality and his special teams talent should get him on the field right away. | After a decent first week, Brooks puts up 2 awful games vs Houston and Dallas. Is anyone still holding? I'm thinking of holding him for one more night tomorrow vs Dallas.
He's getting 20+ minutes and he's considered one of the better rookies this year, but man, if he keeps performing like this... it's hurting my room among all my other injuries. Anyone following him can comment on his potential on the team, or was the first week just a fluke? | 1,999,774 | So, I hear a lot of people say that Zeke's is really terrible on Tahm Kench, since your initial cast on your ultimate is just waiting and then taking you to a new destination, which does sound bad, but Zeke's is actually hidden OP on Tahm and I'll tell you why.
So, as opposed to every other Support who has to wait until it's an effecient time to use their ult to proc Zeke's, Tahm Kench can actually activate Zeke's whenever he wants (as long as cd's are available)! If you have Zeke's on and you want to activate it, simply push your ult button, immediately click to move Tahm Kench in the direction you want to run, and without much of a stutter on Tahm's movement, he'll immediately start running again, activating Zeke's ability while only putting your ult on a 10 second cooldown.
Give it a try, it's really good on him.
Edit: Quick Example Clip: | Tahm Kench Ult Rework Underwhelming | How exactly does Kennen ult work? | [Discussion] How to build Tahm Kench efficiently ? | When should I ult? How to play from behind? | Is Tahm Kench a viable support pick? | Tahm Kench as possible pro champ | Fed as Olaf - Win game - where can i improve as i get higher elo | Draven bug with Tahm Kench |
1,999,775 | Dated on Craigslist; she's now pregnant. | Is Katie McGeeCBS Divorced or pregnant? | Has malia obama ever went on a date? | How long has kelly been dating? | Looks like Hayley in Modern Family got her pre-order early, Google is serious about there marketing
| Is michelle mccool dating undertaker right now? | Who do you think Stephanie McMahon is pregnant for? | Are nelly ashanti getting married? | Who is tracy butler married too and how can you get in touch with her? | 1,999,775 | After dating a lot of (slutty, slutty)girls on Craigslist, I met one that wouldn't even kiss me on the first date; I was intrigued. We started dating and became monogamous, after two years we're having a baby (I'm trying to convince her to let me name him Craig). | The Real Life Encounters of a CraigsList slut | For those of you out there who slutted around a lot, what made you decide to get serious? | Women of Reddit, how come I only seem to get casual sex from girls, but never a real relationship ? | Single-Parent Dating--the Real Scoop! | share your bad dating experience...? | when was the last time someone went to a dating agency | Guys out there: your impression of a girl Hooking up on the first meetup? | Not your Typical Dating Service!! |
1,999,776 | Fluid-filled micro suction-controller array for handling objects | Suction cups work well and it even came with bigger suction cups just in case. Holds all my son's bath toys | We develop a rotationally actuated fluidic device for controlledgeneration of microbubbles in a lab-on-a-compact-disk based environment. Use of such a strategy essentially implicates that one may employ simplistic, versatile, flexible, and economized microfabrication as well as fluidic actuation techniques, instead of more complex traditional methodologies, for microbubblegeneration and control. We further demonstrate that the spatio-temporal frequencies and size distributions of the generated bubbles may be judiciously controlled by simply tailoring the rotational speeds, corresponding to given channel dimensions and fluid-substrate combinations. | Research activities throughout the world concerning micro fluid-handling are reviewed. Pumps and ink-jet heads, valves and flow sensors are discussed. Many research groups are moving into this emerging field, usually, aiming at the development of complete systems for chemical analysis or medicine delivery. Some comments on future trends and opportunities are given. > | Understanding the dynamics of biopolymers in complex flows is critical for the successful design of lab-on-a-chip devices. In this paper, we demonstrate the first direct comparison of experiments and simulations of DNA transport in a pressure-driven post array flow. High aspect ratio ordered silicon posts arrays were microfabricated, and single molecule experiments were employed to examine the dynamics of DNA traversing through arrays of ordered obstacles. Three different geometries with varying post spacing were tested, and probability distributions of DNA hooking location and fractional DNA lengths were generated. It is demonstrated that the appropriate design of post array geometry can be used to control DNA conformation and guide the location of hooking events. Finally, agreement between experimental and Brownian dynamics simulation results is good, validating the simulations that can be used to guide future array designs. | The invention provides a micro-fluidic chip device, consisting of an injection pump, a parallel serial port, a nut, a clamp, a micro-fluidic chip component and a waste liquid trough; the micro-fluidic chip component is formed by the connection of micro-fluidic chips by the parallel serial port; the clamp fixes the micro-fluidic chip component by the nut; and one end of the micro-fluidic chip component is connected with the injection pump and the other end thereof is connected with the waste liquid trough. The micro-fluidic chip device has reasonable design, low preparation cost, convenient and quick operation and quick detection and is convenient for carrying. The micro-fluidic chip device achieves the direct detection of a destination cell in the body fluid by a one-step method, and can be applied to the detection of various tumor markers in the body liquid. The micro-fluidic chip device has wide application prospect on the detection and identification of the tumor. | if the volume was thicker with some more heavy duty suction cups I could mass produce a product I have in mind, but these are very limiting to surfaces that do not move, shame.. no product exists that I need to optimize my gadget :( | This paper reports a new generation of micro air jet arrays, consisting of electrostatic micro actuators generating high-speed micro air jets using acoustic streaming for eventual application in chip cooling, gas pumping, and propulsion of micro-platforms. The microjet array is developed using a simple fabrication process and assembly method. The array contains 24 actuators with a volume of 0.9 × 0.9 × 0.1 cm3 and weighs 0.09g including wires and mounts. Several improvements have been achieved in this generation of devices, including: (1) light weight (smaller by >5×), (2) large diaphragm displacement (~10 μm), and (3) high operating frequency (~100 kHz). A 3.5× improvement in thrust-per-weight ratio is obtained with an average thrust of 0.75 μN per actuator. Diaphragm velocity is measured using a laser vibrometer and a peak jet speed of 7 m/s through the exit throat holes is estimated. | The micromanipulation technology still faces some challenges. Direct rotary step-driving of a microobject has not been realized by physical means. The implementation of 3-D attitude adjustment of a microobject usually involves a complicated driving and controlling system. The capability and controllability of releasing sticky microobjects from a probe is still limited. In this paper, we demonstrate a strategy to use hydrogen bubbles generated by electrolysis of water to manipulate microobjects in water on a substrate surface. Manipulation functions implemented by this strategy include direct rotary step-driving and attitude adjustment of a single microparticle, and controlled release of a single sticky microparticle. | 1,999,776 | Micro suction cup array for wet/dry adhesion | Suction cup adhesive melted | the suction cup sticks like glue to it | Works great! Suction cup sticks well to my tile and ... | How do you get suction cups to work on tile? | Suction Cups Don't Work on Textured Tiles | Perfect solution when suction cups Don't stick to tile! | Enhanced Directional Adhesion Behavior of Mushroom-Shaped Microline Arrays | The suction cups don't even stick to the bottom of ... |
1,999,777 | how many riders participated in the first race across america | History of cycling Cycling quickly became an activity after bicycles were introduced in the 19th century and remains popular with more than a billion people worldwide used for recreation, transportation and sport. The first documented cycling race was a 1,200 metre race held on May 31, 1868 at the Park of Saint-Cloud, Paris. It was won by expatriate Englishman James Moore who rode a bicycle with solid rubber tires. The first cycle race covering a distance between two cities was Paris–Rouen, also won by James Moore, who rode the 123 kilometres dividing both cities in 10 hours and 40 minutes. | Cycling in Canada as evidenced by advertisements. The first person in North America to ride a Penny Farthing style bicycle was Albert Lane who in Montreal rode an imported 50 inch coventry on July 1, 1874. He also co-founded the first bicycle club in Canada, the Montreal Bicycle Club in 1878 which later joined with the Lacrosse and Snowshoe clubs to form the Montreal Amateur Athletic Association in 1881. Before the widespread adoption of private automobiles, bicycles were a popular mode of transport in Canada, although Canada's snowy winters posed a problem for year-round use. Travel by horse and carriage (or sled) or | the Race Across America organization forgave the time cutoff that would have disqualified Parker, and allowed her to re-enter the ride as an official racer. After returning to the race, Parker quickly climbed the women's field, performing what RAAM commentator David Towle called "one of the greatest rides in Race Across America history". Helped by six-time RAAM winner Seana Hogan's early withdrawal (due to respiratory problems), Parker finished first in the women's field with a time of 11 days, 20 hours, and 54 minutes. Maria Parker Maria Parker (born February 7, 1963) is an American long-distance cyclist and the holder | Bicycle touring the world's largest cycling association, and to coin the French word "cyclo-tourisme". The League of American Wheelmen in the U.S. was founded in Newport, Rhode Island on May 30, 1880. It shared an interest in leisure cycling with the administration of cycle racing. Membership peaked at 103,000 in 1898. The primary national bicycle-touring organization in the U.S. is now Adventure Cycling Association. Adventure Cycling, then called Bikecentennial, organised a mass ride in 1976 from one side of the country to the other to mark the nation's 200th anniversary. The Bikecentennial route is still in use as the TransAmerica Bicycle Trail. | The GT America Series is a sports car racing series based in the United States which runs as a support series to the GT World Challenge America. It is managed by the Stéphane Ratel Organisation and sanctioned by the United States Auto Club.
History
The series was announced in October 2020, replacing the GT Sports Club America and the Sprint category of the GT4 America Series. The first race was run on March 6, 2021 and was won by George Kurtz. At the end of the opening season, Charlie Luck was crowned the inaugural overall champion, while Jason Bell won the GT4 class championship.
Class structure
The series places strong emphasis on Bronze-rated and gentleman drivers in the single-driver sprint race format. Races are 40 minutes in length, with no required pit stops. Entries are split into four classes; GT2, GT3 Overall, GT3 Masters, and GT4. The Masters class is exclusively for drivers above the age of 50, similar to the former GT Sports Club's Titanium class. Previous generation GT3 machinery is also homologated for the competition.
Champions
See also
GT World Challenge America
GT4 America Series
TC America Series
References
External links
Official Website
Sports car racing series
Auto racing series in the United States | Touring car racing the subtle bumping and nudging for overtaking much more acceptable as part of racing. As well as short "sprint" races, many touring car series include one or more endurance races, which last anything from 3 to 24 hours and are a test of reliability and pit crews as much as car, driver speed, and consistency. While rules vary from country to country, most series require that the competitors start with a standard car body, but virtually every other component may be allowed to be heavily modified for racing, including engines, suspension, brakes, wheels and tyres. Aerodynamic aids are sometimes added | 2007 BRAG began Sunday, June 9 in Columbus, GA and ended in Savannah, GA on Saturday, June 16. Overnight stops were in the following towns: Bicycle Ride Across Georgia The Bicycle Ride Across Georgia (BRAG) is an annual road-cycling tour across the US state of Georgia. It began in 1980 as an offshoot of RAGBRAI. Between 1,000 and 2,000 riders participate in this great ride every year. The route covers approximately 400 miles over 7 days with options for longer distances. Mid-week, the tour stays two nights in one town allowing riders to either rest or ride a century with | When did F1 racing start? | 1,999,777 | and contested at much higher speeds. The first incarnation of RAAM, The Great American Bike Race, was organized by John Marino in 1982. There were four competitors: John Marino himself, John Howard, Michael Shermer, and Lon Haldeman. The course started in Santa Monica, California and finished at the Empire State Building in New York City, where Haldeman emerged as the winner. Results of the 1982 race: After the first year, the name of the event changed to Race Across America, and participation became subject to qualification rather than invitation. The concept caught on and the event grew larger year after | when did the first trans am bike race start | when does the first great urban race take place | who organized the first british autocross race in 1954 | What's one thing you remember about the first race you watched? | when was the first nxs race outside the us | in which horse race did barney roy win his first major race | who wins the first game of after the race | entrepreneur won which race for the first time in 1996 |
1,999,778 | Population Change Trends in Large U.S. Metropolitan Areas, 1960-70: a Review | During the 1970's the South and West census regions accounted for 89.9 percent of incremental U.S. population and 72.5 percent of incremental nonagricultural employment. These figures are sharply higher than corresponding figures for any other decade in U.S. history. For example, during the 1930's the South and West gained 65.4 percent of incremental national population, which was the highest share previously recorded. The immediate cause of the interregional population shifts is fairly heavy net out-migration from the Northeast and North Central regions to the South and West, combined with birth rates that are near historical low levels. Interactive relationships that cause employment growth and migration to reinforce one another are probably operating, but these relationships are not well understood. They are the focus of this paper. Using a new and unique set of time-series data on migration and employment, we develop and estimate a time-series model of migration and employment growth for each of 171 U.S. regions. Our primary emphasis in this paper is on the 57 major metropolitan | Changes in the absolute and relative size of the elderly population since 1960 are decomposed into the underlying demographic components for metropolitan and nonmetropolitan areas and for nonmetropolitan subregions of the United States. Specifically we examine the components of net migration and natural increase for those aged 0-64 and those 65 or older....In general the aging of the nonmetropolitan population was predominantly due to elderly migration during the 1970-80 decade and to the loss of young people both before and afterward. Recent trends give little support for the view that the 1970s was the beginning of a new phase of deconcentrated settlement even for elderly persons. (EXCERPT) | Demographics of Washington, D.C. expanded highway network outside the city. Following social unrest and riots in the 1960s, plus increasing crime, by 1980 Washington had lost one-quarter of its population. After the achievements of civil rights, more of the city's middle-class black population also moved to the suburbs. The city's population continued to decline until the late 1990s. Gentrification efforts started to transform the demographics of distressed neighborhoods. Recently, a trend of growth since the 2000 U.S. Census provided the first rise in the District's population in 50 years. In 2017, the U.S. Census Bureau data estimated the District's population at 693,972 residents, continuing | What as the main shift in the population in the 1950s? | The authors analyze changes in rural-urban migration patterns in the United States. "Current Population Survey (CPS) migration data from 1990-94 indicate a dispersal of population out of urban areas into small towns and open country areas. The net rural gain has been small according to these data (0.1 percent), but it contrasts sharply with rural outflow of the late 1980s. Even more significantly, the rural ¿brain drain' of the 1980s has not carried over into the 1990s." | NORRISTOWN, Pennsylvania, a mediumsized city twenty miles northwest of Philadelphia, is currently the focus of an intensive study of the changing size, composition, and demographic behavior of its population. This is a report on one phase of this overall study-an attempt to utilize local data to determine the changing patterns of occupational mobility among the male members of the Norristown labor force over the last forty years and to determine what relationship, if any, exists between these patterns of occupational mobility and the patterns of migration into and out of Norristown. For purposes of analysis, four time periods were used: 1910-1920, 1920-1930, 1930-1940, and 1940-1950. | In the past decade New York and Chicago have built tons of new skyscrapers. This is despite the fact that both cities have seen relatively little population growth. Where is the demand coming from in this case? It makes sense to see a building boom in a city like Seattle where the population and surrounding urban areas have been growing rapidly but that is not the case here. A lot of these new skyscrapers are residential but many are also commercial buildings that employ thousands of people. Where are these workers coming from if the population of the cities arent growing?
The city of New York is estimated to have grown only 2% since the 2010 census. The overall metropolitan area actually saw a slight population decrease.
Chicago’s population is estimated to have actually declined 0.1 %. | Depopulation of the Great Plains The depopulation of the Great Plains refers to the large-scale migration of people from rural areas of the Great Plains of the United States to more urban areas and to the east and west coasts during the 20th century. This phenomenon of rural-to-urban migration has occurred to some degree in most areas of the United States, but has been especially pronounced in the Great Plains states, including Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Montana, Wyoming, Colorado, and New Mexico, where many counties have lost more than 60 percent of their former populations. Depopulation | 1,999,778 | Abstract Seven hypotheses relating to change in metropolitan areas in the decade 1960-70 are developed from literature pertaining to the preceding decade. Analysis indicates that most of the trends apparent in the 1950's have continued in the 1960's, including racial polarization, the effects of age and location of SMSA's, the uniqueness of the South, and rapid growth in the Southeast and West. Several hypotheses were rejected: (1) black suburban populations remained constant, (2) suburbs in the South are losing nonwhites, and (3) SMSA's in the South decentralize more slowly than elsewhere. The influences of annexation, migration, and natural population increase on metropolitan change are briefly discussed. | Metropolitan population growth and distribution in the American South, 1970-1990. | Changes in the Scale and Size Distribution of US Metropolitan Areas during the Twentieth Century | In the recent decades southern European cities experienced morphological changes and a demographic transition towards zero (or negative) growth and aging. Population dynamics shifted from the impressive growth of the post-industrial period into recent de-concentration processes determining the spillover of commercial and residential settlements across the surrounding rural areas. Based on long-term demographic data, the present study hypothesizes that urban expansion did not follow a one-way linear path from compactness to dispersion while reflecting differentiated growth patterns based on the specific socioeconomic context at the local scale. Along a sufficiently long time period non-linear expansion waves alternating settlement densification and scattering are expected to be found especially in complex urban contexts such as those developed in the Mediterranean region. This hypothesis was tested for a paradigmatic case study in southern Europe (Athens, Greece) using demographic data covering 160 years (1848–2011). Urban growth in Athens was assessed through the analysis of long-term census data made available on a district level. These data provide information on the spatial distribution of resident population and characterize distinct expansion waves according to the dominant socioeconomic context. Results of the study were discussed in the light of the debate on future development of the Mediterranean cities and the (changing) economic relations with the surrounding region. | Did suburbs grow outside american cities in the 1950s? | 50 years of population change along the nation's coasts 1960-2010 | Changes in city planning driven by population shift, and ... | Changes in the Distribution of Poverty across and within the US Metropolitan Areas, 1979-89 | And Did the Walls Come Tumbling Down? Ethnic Residential Segregation in Four U.S. Metropolitan Areas 1980-2000 |
1,999,779 | Abnormal Chromosome 18 in prenatal diagnosis with holoprosencephaly | The incidence of holoprosencephaly with normal chromosomes has been estimated at between 1 in 16 000 and 1 in 53 394 live births. It has been found that during a 3-year period in the Bristol and Weston Health District there were six cases of holoprosencephaly, two of which were familial, and these cases are described. This represents an incidence of 1 in 5200 and during the preceding 3-year period the incidence in the same area was 1 in 14 520 births. | A three generation pedigree is described in which there are two carriers of translocation t(7;18). Two members of the family have trisomy 18p and a stillborn child had monosomy 18p and holoprosencephaly. Another stillborn child probably had holoprosencephaly; the karyotype was not analysed. Based on this observation, the occasional occurrence of holoprosencephaly in monosomy 18p (10% of previously reported cases) may not be the result of the expression of a recessive mutant gene in the hemizygous state, as assumed up to now. | Cytogenetic, Molecular, and Phenotypic Characterization of a Patient with de novo Derivative Chromosome 18 and Review of the Literature | Introduction: The syndrome by deletion of the short arm of chromosome 18 is an infrequent syndrome, and its phenotypical variability makes it difficult to recognize. Its most frequently observed clinical characteristics include mental retardation, growth retardation, craniofacial malformations, including long ears, microcephaly and short neck; other less frequent associated malformations include holoprosencephaly. ::: Case report: We present two patients with deletion of the short arm of chromosome 18, one presented a de novo mutation and the other was produced by a balanced translocation 6p/18p of maternal origin. Both patients presented alobar holoprosencephaly and cebocephaly, low-frequency clinical characteristics in this syndrome. ::: Discussion: alobar holoprosencephaly is a malformation appearing in 10% of patients with deletion of the short arm of chromosome 18; we review the probable physiopathology of holoprosencephaly in this syndrome. | A normal female with an 18p—chromosome but without any feature of the 18p—syndrome produced a cebocephalic child whose karyotype included an 18p—chromosome. Evidence is presented that the normal female is a nonreciprocal translocation heterozygote resulting from the short arm of one chromosome 18 becoming attached to the long arm of a chromosome 12. | Rett syndrome consists of a characteristic progressive encephalopathy in females. The cause of this syndrome is unknown. We present a patient with 18q-mosaicism who, along with the characteristics of this autosomal deletion, also fulfills the clinical criteria for Rett syndrome. This may demonstrate heterogeneity within this as yet clinically defined syndrome. A thorough chromosomal analysis should be performed in suspected cases of Rett syndrome. | Background ::: Deletions of the long arm of chromosome 18 cause a common autosomal syndrome clinically characterized by a protean clinical phenotype. | The association between agnathia and holoprosencephaly is well documented (Pauli et al., 1981). Pauli et al. described two female sibs with agnathia and holoprosencephaly who were subsequently shown to carry an unbalanced 46,XX, der 18,t(6;18)(pter p24.1) karyotype (Pauli et al., 1983; Krassikoff and Sekhon, 1989). All other cases have been sporadic (Cohen, 1989). We present a recurrence of agnathia-holoprosencephaly in an unrelated European couple and postulate that this association may represent an autosomal recessive syndrome. | 1,999,779 | Prenatal Diagnosis of Alobar Holoprosencephaly, Cyclopia, Proboscis, and Isochromosome 18q in the Second Trimester | Prenatal Diagnosis of Anterior Encephalocele | Gastroschisis and omphalocele: Prenatal diagnosis and perinatal management | Prenatal detection of intraamniotic bands: implications and management. | 18p-syndrome: Presentation of two cases with alobar holoprosencenphaly | Prenatal Diagnosis of Tetralogy of Fallot with Absent Pulmonary Valve Accompanied by Hydrops fetalis | Intraventricular fused fornices: a specific sign of fetal lobar holoprosencephaly | Diagnosis of a viable abdominal pregnancy by magnetic resonance imaging. | Abnormal first trimester screen in partial deletion of chromosome 6p21: a case-report. |
1,999,780 | Unit is measure to height? | Difference between height and lenght when measuring? | What unit is measured with a ruler? | 1 foot is equals to? | What can measure an inch a unit? | What is 157 centimetres in feet? | Both the measures height and length can be expressed in terms such as meters, inches, feet and so on. The term height refers to how tall is an object. whereas length refers to how long is the object. | What does imperial units measure? | What is the unit of measurement of a door? | 1,999,780 | What unit is used to measure people's height? | How do a measure your height? | What units is used to measure the height of a bookcase? | Hey Saffers, do u measure your height in feet and inches or meters? | What height is considered as tall? | Routine measurement of children’s height is essential in monitoring for deviations in normal growth velocity. Target adult height of children is estimated by determining an adjusted midparental height. Such determinations are dependent on the accurate acquisition of parental height. Incorrect assessment of parental height will result in inaccurate expectations for the child’s height. To observe the difference between stated and measured parental heights within a United States subspecialty setting, prospective acquisition of parental stated and measured heights during the summer months of 2000 and 2001 was examined. Two hundred and thirty-eight parents, 185 mothers and 53 fathers, were measured. The mean values of the stated heights for mothers and fathers were 163.7 cm ± 6.3 cm and 177.1 cm ± 8.6 cm, respectively. The corresponding measured heights were 163.0 cm ± 5.9 cm and 175.2 cm ± 6.6 cm, respectively. The mean height difference for mothers was 0.69 cm (p<0.001) while the mean height difference for f... | Do people usually measure their heights with shoes on or off? | What is the measurement of anemometer? | Would you measure a desk with meters? |
1,999,781 | Eladio Dieste: Innovation in Structural Art | The Tower and the Bridge: The New Art of Structural Engineering | Thank you very much for downloading horta and after 25 masters of modern architecture in belgium. Maybe you have knowledge that, people have look hundreds times for their favorite books like this horta and after 25 masters of modern architecture in belgium, but end up in harmful downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they juggled with some infectious virus inside their laptop. | A compilation of recent inovatory church architecture from around the world with a brief historical overview. Varying photographic coverage and plans, and with coffee table text. Generally slanted towards "high art" architecture. A worthwhile current reference for anyone involved in church architecture. | Because architecture provides a ‘concrete’ focus for many debates pertinent to collective identities, then the rebuilding of the Ground Zero site by architect Daniel Libeskind is hugely significant from the perspective of sociology. So-called ‘starchitects’ such as Libeskind are increasingly conscious of the complex identity discourses within which their work is situated, with competing identity claims evidenced not only in the actual form of buildings, but also in the abstract narratives architects use to situate their work in a way that avoids (symbolically) privileging one identity over another.The capacity of architects to position their buildings in this way provides the focus of this article, which argues that architects’ discourses frequently reveal many tensions between culture, politics, power, and identity.The symbolic nationalization of the architecture at the Ground Zero site has, in part, been achieved by the narrative, highly symbolic links between the buildings there and an ‘American’ colle... | Eero Saarinen on His Work: A Selection of Buildings Dating from 1947 to 1964 With Statements by the Architect, | Info about draw bridge made? | This study is concerned with the New Acropolis Museum, which was opened in June 2009 in Athens. The New Acropolis Museum, out of all of the world’s new museum structures of the past century, has dramatically intensified the issue of the relationship between parts and the whole, between the building and its integration into the setting, between the museum function and the historical city, which is a protected heritage site, one treated as a museum exhibit. With the New Acropolis Museum as an example, the study would like to highlight the complexity and the ambiguity of the present-day relationship between the heritage protection, the museumisation of art and the design of our environment. The particular attention is focused on the vivid debate about the building and the distinguishing the differences between traditionalist and modernist views of architecture manifested in this debate. These differences are deeper rooted than many people have been willing to admit. | The question is examined as to what extent the designer should consider the method to be used for construction when he is preparing the design. Four case histories of steel bridges provide examples, and conclusions are drawn about the appropriate involvement of the designer. The case studies include the Carnes Creek Bridge, the Pashleth Creek Bridge, the Alex Fraser (Annacis) Bridge (the world's longest span cable stayed bridge when it was constructed in 1986), all in British Columbia, Canada, and the Peace River Bridge, Alberta, Canada. The French title of this article is: Projet de ponts metalliques en vue d'une execution aisee. The German title of this article is: Zum Entwurf montagefreundlicher Stahlkonstruktionen. For the covering abstract of the conference see IRRD 851274. | 1,999,781 | The double-curvature masonry vaults of Eladio Dieste | Structural behaviour of historic masonry cross vaults | Numerical analysis of Masonry Spandrels with Shallow Arches | what type of domes are elliptic parabolic vaults | A computer model for the analysis of masonry columns | A numerical model for the study of ancient masonry structures | Thrust network analysis of masonry vaults | CHARACTERIZATION OF THE MORTARS OF EL CASTILLO DE SAN CRISTOBAL | Seismic Response of a Historic Masonry Construction Isolated by Stable Unbonded Fiber-Reinforced Elastomeric Isolators (SU-FREI) |
1,999,782 | [Offline][CA][St. John's, NL][5e] Looking to DM or join a group | Started playing DnD this weekend while at PAX Australia and would like to do it more frequently. Already have some friends that would be happy to join, but need someone to primarily DM the session. Anyone that's wants to help the group get started would be appreciated. | I'm looking to get a group going in Knoxville, TN (ideally west Knoxville) that would meet, at least to start, at a local game store.
I currently DM an online group but have never played in person. And my DMing happened only because I couldn't find a group to play in myself, so my first foray into D&D was DMing. (To be clear I'm looking to be a player, not a DM, for this.)
**When:** I'm married with young kids (in my 30s) which makes it difficult to commit to something every single weekend. I'd prefer to find a group that could meet mostly during the week (say, starting at 6pm on a Tuesday, Wednesday, or Thursday). Throwing in 1 weekend afternoon per month could work as well. I have a consistent M-F 8-5 type work schedule so no worries about my availability shifting unless I'm traveling.
I'd like to start sometime in August.
**Who:** I'm looking to play with people who are in the same boat as me: where carving out an extra 4 hours per week/two weeks isn't easy and will commit, communicate well if they can't make it so we can reschedule (traveling for work, sick, etc.), and understand that for whoever DMs the amount of work isn't insignificant, so honor that by showing up.
**Theme:** I think playing through one of the prewritten modules would be easiest to start, but I'm open if a DM has a homebrew they want to run. I got into D&D through Matt Colville, MCDM, and Critical Role, and not that I'm expecting production value like that but what I see from those is a group of people that have fun together, roleplay their back stories, aren't pure murderhobos, work together, etc. (I’ve run through Lost Mine of Phandelver and dovetailed it into Storm King’s Thunder for my online group so would prefer something else so I don’t know where everything is headed.)
**Where:** I don't have any relationships with any of the local game stores, but I visited both Level Up and The Game Piece yesterday. I'm in the N Cedar Bluff/Middlebrook area and The Game Piece is about a 20 minute drive, but they were nice enough to give me a little tour and you can reserve rooms in advance, etc. Level Up was too busy with a lot of customers in the store to really talk with anyone but I'm open to that as well.
I've seen posts by u/RamzaBeoove]( [u/gumsoul27]( and [u/obscvrehero in terms of messaging people and making sure they're good to go each week, etc. if that makes life easier on the DM. | Hello!
I am an experience D&d player looking to join an online 5e group. I am interested in meeting up with a group either twice a month or every week depending on availability. EST weekday evenings usually work best.
I am limited experience DMing but would be willing to introduce a small group into my homebrew if that is what the group needs.
Message me if interested! | Hello everyone!
I've recently moved to Hebden Bridge and miss playing D&D dearly, so I am looking to form a new group here. I've been playing with a group for half a year where I lived before, and had just started to DM Curse of Strahd w hen I had to move away. I'd be happy to be DM, if someone really wants to DM though I'll also be happy as a player! We don't have a perfectly furnished flat here yet, but I'd be happy to host.
New players would be very welcome! | You're invited to my new group 'Summer in College Station' on GroupMe. Click here to join: | I may have inadvertantly started a DC area Corgi Meet-up group.
Anyone interested in meeting up next weekend?
Name a time & place. | I am doing a loop with some friends from New Haven on this coming Saturday and am looking for a few fellow riders to join along.
#sthash.BYWMPBo7.LJkpVvPy.dpbs
PM me if you have any interest and I'll send details. | Hello we are a group of adventurers who are seeking a DM as well as one more player. We have currently had 2 DM's that have had to bow out before we could get started so we have characters ready to go and are itching to play! Typically we play on Saturdays. | 1,999,782 | I'm a student going to MI here in St. John's (originally from Ottawa), and I've always wanted to play or DM, but never really had the chance to do it when I was younger. If anybody from the area would be interested in either starting a campaign, or if I could potentially join an existing one, I would be eager to join. | anyone interested in role-playing in Dm? | [Online] [5e] [EDT, Toronto, GMT-4]- Looking for players in Toronto/ Ontario to join a new campaign that will take place every second Thursday night beginning Thursday 16th April @6:30pm | [D&D][5e][Online][PST][LGBTQ+/BLM Friendly][18-21+] 30 Year Old Semi-experienced DM looking to join Campaign | Where to find people who enjoy playing campaign. | M 19 looking for new people to play with | Lacking some motivation and would like to find some fellow losers to join with on MFP! | Anyone interested in getting together on weekends to play some road hockey? | [5E][CT][Online][Flexible]Dm looking for a group of new players who want to have a fun first campaign |
1,999,783 | [W2C] Nice branded tote bags | I purchased this Dooney and Bourke Chelsea tote directly from the manufacturer. Like all Dooney and Bourke leather bags, this tote is manufactured from high quality, heavy materials and is solidly constructed. In light of its solid construction, this tote is designed to withstand daily use without looking worn and tattered in a short time. I am so pleased with this product that I anticipate purchasing additional Chelsea totes in colors that complement by wardrobe and/or reflect the changing seasons. | I thought when I ordered this, that I wanted a tote. After receiving this one and another tote that I had ordered at the same time, I realized that it was just too much to "tote" for a purse. Sorry about the pun! | I really like this vac BUT the bags from Waring are so darn expensive. The only way you can find the bags is here online!! No stores carry the bags but they do sell the vac pistol, doesn't make sense does it?? Now here is what I have found out and it has SAVED me money!!!! I found that the FOODSAVER bags in the blue packaging works just the same as the Waring bags AND they are HALF the cost too!!! I hope this helps you and saves you money because it will save you money!! The FOODSAVER bags are the same thickness and the same ziplock!! REMEMBER.........THEY ARE IN THE BLUE PACKAGING!! The other bags in the green packaging is for the heat and seal!! So, that's my review!! I love the pistol but hate the price of the bags!!! | I'm looking for a tote bag to promote veganism while carrying home my super expensive vegan salad(because we only eat salad am I right?). I don't want anything too "in you face" and preferably something with the environment. I love the designs of both "vegetaryn" and "In the sunshine" but unfortunately they didn't have any tote bags that I liked.
If you have any tips for brands or websites with vegan tote bags please share:) | I love, love, love this tote. The teal color is unusually fantastic and much deeper and richer than the photos. The construction of the bag is sturdy and stylish. Also, unlike most lower priced bags, there are no noxious odors (gals who love Chinese knockoffs know what I am talking about here). Great huge tote all around. I will be using this a lot down here in FL. | "eating chocolate cake in a bag", which was at the Vienna press conference, and the second is in the song "Come Together", where he sings: "He bag production". This is a reference to Bag Productions Ltd, Lennon's public relations company, which derived its name from Bagism. The third reference is in "Give Peace a Chance", with the line, "Everybody's talkin' about Bagism, Shagism, dragism, Madism, Ragism, Tagism, This-ism, That-ism, ism, ism, ism." A website called Bagism was created c. 1994 by Sam Choukri, providing John Lennon and Beatles links, photographs, rare sound recording snippets and video. At one point, c. | 1. Baggu Reusable Bags
2. BahrEco Produce Bags
3. Society6 Canvas Tote Bags
4. Zero Waste Net Bag
5. Canvas Market Bag
6. Baggain Recycled Denim Bags
7. Apolis Jute Market Bags
Link to article | matter, from minimally-processed natural fibers, or from byproducts of processes that refine organic materials. The term tote or tate, meaning "to carry", can be traced back to the 17th century but was not used to describe bags until 1900. However, the tote bag craze in the United States began in the 1940s with the release of L.L. Bean's Boat Bag in 1944. Because they were easier than carrying luggage, most people opted for using tote bags. During the 1950s, tote bags began to enter into the main culture. Women primarily utilized them as practical handheld bags because they didn't require | 1,999,783 | It's getting hella hot here in Europe, so it's almost time for some nice bags to take to the beach. Just looking for some nice cheap branded tote bags (doesn't really matter what brand) to carry my other rep summer stuff. Link me up! | Great bag to use in summer | Summer Tote Bag Follow-up with T-Force | when did the tote bag become popular | Super beach bag or overnight bag. | A mesh bag is a great idea for the beach | This was a great bag to take to the beach with my sons' ... | Great bag for the beach | so far I love it you get 2 bags in one a tote ... |
1,999,784 | Why are creationists so arrogant? | The Creationists: The Evolution of Scientific Creationism | Why does a person that does not believe in evolution get labeled as stupid. Btw I am not a creationist. What makes it so critical to science? Seems hokey without observable experiments and math that seem to be required by the rest of the sciences. I know about micro evolution btw. Help [serious] | The recent massive attack by fundamentalist Christians on the teaching of evolution in the schools has left scientists indignant and somewhat bewildered. Creationist arguments have seemed to them a compound of ignorance and malevolence, and, indeed, there has been both confusion and dishonesty in the creationist attack. First, there has been a confusion, partly deliberate, of the fact that organism have evolved with theories about the detailed mechanics of the process. The facts of evolution are clear and are not disputed by any serious scientific worker. | Recently i saw a post about how science JUST figured out the neanderthals evolved much faster than previously thought, and i thought it a perfect opportunity to spread the word about a creationists theory that has been debated for decades now by the greatest evolutionists and still stands.
With a layer of ice in the atmosphere, the air density and oxygen levels would be much much higher, explaining the loss of enormous creatures like dinosaurs AND the recently found information that "neanderthals" evolved in a quickly. With that, the intense pressure would also allow humans to run for hours on end without losing there breath as well, which i thought was pretty cool, but i digress...
The Bible talks about a flood, and science has proof that there was a flood pre-history, but where did all the water come from? That's right, the ice melted at a certain point.
Now, there IS evidence that the earth was created instantaneously through an element that only lasts milliseconds but left it's un-moved signature in rock formations with a perfect circular signature, insinuating that, "in a flash", earth came to be. it's on youtube somewhere.
Anyway, I'm just saying, all this evolution talk and darwinism going around isn't just because it is the only logical option(they have most of the money and bias in the science community), but in fact, the world's leading theorists on the subject still haven't created complex organisms with brains and lungs from single celled ones, as in a primordial ooze THEORY. (They have been trying since the 50's to recreate the event and have NEVER succeeded)
You are going to believe what you want to believe, and if you don't have any thinking to do, don't bother commenting, but this theory always made a lot of sense to me, and i wondered if anyone could expand. Thank You. | There are many problems with this book, the first of which is the title. The book argues that scientists confront creationism however, this is not only deceiving but flat out wrong. The title implies that all scientists reject creationism, this simply isn't true. Thousands of scientists across the globe accept creationism.
There are many misconceptions that devalue any real purpose this book could have. However, there are some good points in the book. Problems with radioactive dating are admitted to some extent. However there is no mention of the unprovable assumptions that must be made. There is no sure way to know that the decay rates have remained constant throughout time, or that the rates haven't been dramatically increased throughout time.
The creationist view of the geological record is examined. The writers scoff at the notion that creationists argue that the geological column was built upon the assumption of evolution. Evolutionists, like some reviewers here, often point out that the geological record was formed be for Darwin wrote his book. They fail to understand, however, that evolution was accepted WELL BEFORE Darwin!! Darwin may be known as the father of evolution, but that doesnt mean Darwin founded evolution. Heck, even Dariwn's OWN grandfather believed in evolution, yet evolutionists seem to forget when they think about the geologcial column! I wonder why evolutionists have such a hard time understanding history? Could it be because of their own preconceived ideas about history?
The chapter on the statiscal improbability of evolution is a complete joke! No probabilties are examined as to whether or not darwinism could have occured. Moreover the evolutionists show their ignorance for the subject of statistics. A recent book by Lee Spetner puts their ignorance of statisics to shame. If you want to understand why mathematics argues AGAINIST darwinism, check out Spetner's work, Not By Chance.
This book implies that creationists are not scientists and that evolutionists are scientists. This is the biggest error of the book. Neither creationism nor evolutionism are scientific theories, they are instead historical theories. It is sad to see not only this propaganda about creation being unscientific and evolution scientific being spread twenty some years ago, however, it is even worse to see this myth being carried on today. This book gives an unblanced view of what creationism is. There are much better books out their to read. | No intent to abuse or convert, just curious. I am an atheist and I do not believe in creationism and I understand (up to my level of intelligence) the evolution theory. Why can't religious groups understand the evolution theory and also hold the belief that a divine spirit created that theory? | Does anyone else find most members to be incredibly arrogant? I mean they blatantly disregard much of history and science and they spend no time asking the hard questions. Isn’t it obvious that many exmos are exmos because they read and ask questions? Does this arrogance and apathy drive anyone else wild? | 50 highly qualified scientists give their reasons for believing the Bible's account of Creation. Most people don't know anyone who has a PhD in science and believes in Creation. These 50 are just the tip of the iceberg - many more would share the same view. | 1,999,784 | We had a biology class where the topic was evolution. Now about 90% of my class are agnostics and will be believe in science over God any day but a few Christians flat out refused to believe in evolution and someone literally said: "Ma'am there is no such thing as evolution". Eventually the teacher gave up and stopped trying to teach them. What I want to know is why people who don't believe in evolution are so goddamn arrogant? Is it so difficult to accept facts and scientific evidence? | My dads friend has a degree in biology and knows evolution is true yet still believes in God for some reason. Found on r/atheism | Evolution doesn't disprove God. A study of the Bible does. | what is the fallacy of ignorance in science | What percentage of Christians don’t believe in Evolution? | To Atheists: Why such a disdain of philosophy? | How do we know that the vast majority of science agrees with evolution? | Faith in God does not have to equal denying evolution and science. | Why do atheists spend so much time teaching Christians what their bible says is fallible ? |
1,999,785 | Nineteenth-Century Arab Trade: the Growth of a Commercial Empire | What products and ideas did muslims trade? | What was the importance of trade? | What discovery greatly affected teh economies of many middle eastern countries? | This paper examines the movement of trade cards in 18th-century consumer and collecting cultures. These unique graphic advertisements supported socio-economic relationships for a limited period in the history of consumption and became sought-after graphic commodities. I consider the ways in which trade cards traversed public commercial centres and private domestic spaces as mobile advertisements, personalized bills, and miniature artworks accruing new meanings and uses as they passed through space and time. The paper complicates the traditional categorization of trade cards as “ephemera.” It suggests that trade cards, rather than functioning as throwaway fragments of promotional culture, circulated within commercial society and collecting circles as valued tokens of private economic exchanges and rarefied objects. | The two major items of trade western africa were? | In 1400s what was the most important trade good from the east? | Two major items of the trade in western africa were? | The triangle trade and columbian exchange are terms used to describe the movement of goods between western europe and west africa and? | 1,999,785 | The expansion of Arab caravans and Arab personnel into the interior of East Africa throughout the nineteenth century was in a sense the first stage of imperialism which was to transform the face of Africa in the twentieth century. Nineteenth-century Arab trade did not produce such radical changes as the European imperial trade which followed. The technology of transport was still based on human muscle power, the main export goods were ivory and human beings which were exchanged for cloth and a few iron goods. The Arabs were concerned almost exclusively with the export-import trade. Unlike the Europeans they did not have the physical means to set up central government controls in any part of Eastern Africa. Yet, despite this lack of innovation, by the 1880s there were very few areas that had not been influenced by the Arabs’ activities in one way or another. | Central Africa developed slower because the need for innovation was lower? Thoughts? | Attempt at the Impetus,Features and Factors of Middle-East Modernization | what type of ships are used to transport oil around the horn of africa | Aspects of early West African trade | Two factors preventing industrialization in africa? | Arab Trade Dynamics after the Implementation of the Pan Arab Free Trade Area (1998–2012) | What technology made it possible for Europeans to begin exploring overseas? | what was the name of the 19th and early 20th century idea to unite the |
1,999,786 | Preparation and electrical properties of humidity sensing films of BaTiO3/polystrene sulfonic sodium | Abstract Nanocrystal BaTiO3 and polymer (R)nM+X− are mixed to make a composite material. IR and XPS spectra of the composite material were analyzed and compared with those of BaTiO3. The humidity sensor made of the composite material shows better humidity sensing properties than the BaTiO3 sensor such as higher sensitivity and smaller humidity hysteresis. | Abstract Barium titanate (BaTiO 3 ) nanofiber was synthesized by electrospinning and by using the calcinations technique. Its morphologies were characterized by scanning electron microscopy, which showed that its average diameter was 80–200 nm, and its length was over 0.1 mm. An impedance-type humidity sensor was then fabricated based on this BaTiO 3 nanofiber. It was unexpected to find that such sensor exhibited fast response and recovery, which were 5 and 4 s between 11% and 95% relative humidity, respectively. The long stability and humidity hysteresis properties of this sensor were also tested, and they were found to be optimum. These excellent sensing characteristics prove that BaTiO 3 nanofiber is applicable for high-performance humidity sensors. |
Introduction
Humidity sensors play a crucial role in environment control, food science, plant cultivation, and the medical field [1]. In 1996-1998, high sensitivity humidity sensors using quartz oscillator and open capacitor were reported, which have advantages of fast response time, immunity to electromagnetic interference and high temperature stability. Besides, the differential sensors made of ceramic material are low-cost and required for high precision measurements [2,3]. Currently, the humidity sensing materials include semiconductors, perovskite oxides, and polymers [4][5][6][7]. Among these materials, sensors based on perovskite oxides are of high reliability and sensitivity. Some perovskite-type materials such as NaTaO 3 , BaTiO 3 and LaFeO 3 have been reported in the literature for their humidity detecting applications [6,8,9]. SrTiO 3 is recognized as one of the most promising perovskite oxides for sensing applications. Its wide band gap and large exciton binding energy induce excellent electrical and optoelectronic properties [10], owing to which the material conducts electrically at room temperature through the adsorption of water molecules on a surface. Interestingly, there has been limited research work performed on SrTiO 3 based sensors and the primary focus has been on the conventional white SrTiO 3 (band-gap 3.2 eV for bulk material).
However, to the best of our knowledge, the sensing properties of dark colored SrTiO 3 such as humidity sensing, gas sensing, or photo-sensing characteristics have never been reported. Some research work regarding dark colored semiconductors was published by X. Chen in 2011. The black TiO 2 with a narrow band-gap of 2.18 eV shows great solar absorption for photocatalysis application [11]. Thereafter, the black TiO 2 has attracted considerable attention due to their enhanced photoelectric properties [12]. In the current work, gray TiO 2 /SrTiO 3 composite with a narrow band-gap was successfully prepared by a facile one-step synthetic method. The gray composite exhibits better humidity sensing performance in comparison with pure SrTiO 3 . Moreover, a narrow band-gap would be more favorable for generation of excited carriers and an increase in conductivity. Hence, sensors based on the dark colored semiconductors might possess more flexibility in realization of high performance multifunctional sensors, which endows composites with wider applications.
In the current work, gray TiO 2 /SrTiO 3 composite nanocrystalline was synthesized in order to be used as a sensing material. Thereafter, the humidity sensor was fabricated by coating the material on carbon interdigitated electrodes. The humidity sensing characteristics were studied by measuring the impedance at different relative humidity (RH). The device shows excellent sensitivity, good linearity, and small hysteresis, which demonstrates that gray TiO 2 /SrTiO 3 composite is a suitable candidate for humidity sensors.
Experimental Procedure
In the experiment, 14 mL tetrabutyl titanate was dissolved in 20 mL ethanol. Then, 1 g urea (used for N doping) was dropped to obtain solution A, whereas solution B contained 5 mL deionized water, 10 mL ethanol, and 1 mL hydrochloric acid. Thereafter, solution B was gradually added dropwise to solution A under stirring with a glass rod until a white colloid was formed. Thereafter, colloid was kept in a water bath heated at 35 • C for half an hour. Subsequently, equimolar Sr(NO 3 ) 3 (Sr:Ti = 1:1) was added into the mixture under magnetical stirring. The resulting material was calcined in N 2 flow under atmospheric pressure at 500-800 • C. The material synthesized at low temperature was TiO 2 /SrTiO 3 composite; while that obtained at high temperature was more apt to form pure SrTiO 3 . The synthesized sample was mixed with deionized water in a weight ratio of 5:1 to form a paste. The paste was coated on a ceramic substrate (1.0 cm × 0.5 cm) with four pairs of carbon interdigitated electrodes to form a sensitive film. The film was dried in vacuum at 60 • C. The preparation details of black TiO 2 are given elsewhere [12].
The crystal structure of the sample was examined by X-ray diffraction (XRD, Bruker, D8 Advance, Karlsruhe, Germany). The optoelectronic characterization of the films was examined by PerkinElmer UV/Vis spectrometer (Lambda 650 S, Waltham, MA, USA) at room temperature while Scanning electron microscope (SEM) (LEO1430VP, Zeiss, Jena, Germany) was used to investigate the morphology. The electrical properties of the sensor were measured by a Precision Impedance Analyzer 6500B Serious from Wayne Kerr Electronics (London, UK). For the humidity sensing properties test, the sensor was put into six chambers with different RH values. The RH values ranging from 11 to 95% were obtained via using different saturated salt solutions as humidity generation sources. These saturated salt solutions were LiCl, MgCl 2 , Mg(NO 3 ) 2 , NaCl, KCl, and KNO 3 and the corresponding RH values were 11%, 33%, 54%, 75%, 85%, and 95%, respectively. The voltage was set at AC 1 V and the frequency changed from 40 Hz to 100 kHz in humidity studies. All the above device performance tests were operated at room temperature controlled by air conditioning.
Results and Discussion
The X-ray diffraction (XRD) patterns of black TiO 2 , gray TiO 2 /SrTiO 3 composite and pure SrTiO 3 are shown in Figure 1a. The diffraction peaks of gray sample can be indexed to be peroviskite SrTiO 3 and brookite TiO 2 composite. The black sample corresponds to the black TiO 2 with anatase type, and the third sample shows pure SrTiO 3 with perovskite structure.
The dark color indicates the enhanced light absorption of the sample. The UV-visible absorption spectrum of gray TiO 2 /SrTiO 3 composite is shown in Figure 1b. It is found that the absorption edge of the composite is approximately defined, which shows that absorption of the gray sample in visible light region is enhanced, in comparison with pure SrTiO 3 . According to the relationship between band-gap and absorption edge, Eg = 1240/λ (where Eg is the band-gap of semiconductor, λ is the light wavelength), the band gap of composite is estimated to be less than 2 eV [13]. These results demonstrate the potential of the composite in photo-sensitive applications. Inset is the picture of actual humidity sensors based on the three samples, respectively. Figure 2a,b display the general morphology of the gray TiO 2 /SrTiO 3 composite studied via SEM at different resolutions. It shows that the composite has a cube shape and the average size is about 150 nm. A uniform and crack-free TiO 2 /SrTiO 3 sample is obtained, demonstrating that the composite is suitable to act as a substrate material for humidity sensors. demonstrate the potential of the composite in photo-sensitive applications. Inset is the picture of actual humidity sensors based on the three samples, respectively. Figure 2a,b display the general morphology of the gray TiO2/SrTiO3 composite studied via SEM at different resolutions. It shows that the composite has a cube shape and the average size is about 150 nm. A uniform and crack-free TiO2/SrTiO3 sample is obtained, demonstrating that the composite is suitable to act as a substrate material for humidity sensors. The relationship between impedance and RH for TiO2/SrTiO3 humidity sensor at various frequencies is shown in Figure 3a. In the low frequency regions (50 Hz and 100 Hz), it can be seen that the impedance decreases with an increase in frequency and changes by far more than four orders of magnitude with a gradual increase in RH. The sensor presents a higher sensitivity compared with other ABO3-structured semiconductors reported previously, such as SrTiO3 nanospheres, NaTaO3, BaTiO3 [6,8,14]. The high sensitivity is closely related to the N-doping in composite, which induces more oxygen vacancies as an active site to adsorb more water molecules [12]. demonstrate the potential of the composite in photo-sensitive applications. Inset is the picture of actual humidity sensors based on the three samples, respectively. Figure 2a,b display the general morphology of the gray TiO2/SrTiO3 composite studied via SEM at different resolutions. It shows that the composite has a cube shape and the average size is about 150 nm. A uniform and crack-free TiO2/SrTiO3 sample is obtained, demonstrating that the composite is suitable to act as a substrate material for humidity sensors. The relationship between impedance and RH for TiO2/SrTiO3 humidity sensor at various frequencies is shown in Figure 3a. In the low frequency regions (50 Hz and 100 Hz), it can be seen that the impedance decreases with an increase in frequency and changes by far more than four orders of magnitude with a gradual increase in RH. The sensor presents a higher sensitivity compared with other ABO3-structured semiconductors reported previously, such as SrTiO3 nanospheres, NaTaO3, BaTiO3 [6,8,14]. The high sensitivity is closely related to the N-doping in composite, which induces more oxygen vacancies as an active site to adsorb more water molecules [12]. The relationship between impedance and RH for TiO 2 /SrTiO 3 humidity sensor at various frequencies is shown in Figure 3a. In the low frequency regions (50 Hz and 100 Hz), it can be seen that the impedance decreases with an increase in frequency and changes by far more than four orders of magnitude with a gradual increase in RH. The sensor presents a higher sensitivity compared with other ABO 3 -structured semiconductors reported previously, such as SrTiO 3 nanospheres, NaTaO 3 , BaTiO 3 [6,8,14]. The high sensitivity is closely related to the N-doping in composite, which induces more oxygen vacancies as an active site to adsorb more water molecules [12].
Additionally, at low frequencies, RH has a close-to-linear relationship with impedance, while there is no clear linearity of relationship at high frequencies. A high sensitivity and good linearity can be obtained at 100 Hz. Hence, 100 Hz was chosen as the ideal working frequency. Moreover, the impedance of referent ceramic substrate remained constant w.r.t change in RH, which signifies that the substrate has no contribution in humidity sensing. Figure 3b shows the impedance versus RH curves of sensors based on different samples at 100 Hz. The sensitivity of pure SrTiO 3 device changes by about three orders of magnitude while that of black TiO 2 changes within one order of magnitude. The gray sample-based sensor exhibited a much higher sensitivity in comparison with that of black TiO 2 and pure SrTiO 3 . The composites composed of different materials usually combine advantages of the components with better properties. For example, In 2 O 3 -NiO, ZnO-In 2 O 3 and MoO 3 -NiO composites all exhibited enhanced humidity sensitive characteristics [5,15,16]. The strengthened moisture properties may be attributed to the improved specific surface area and more active sites in composite. A large surface area-to-volume ratio means that a significant fraction of the atoms or molecules are surface atoms that can participate in surface reactions [15,16]. The relationship between impedance and RH for TiO2/SrTiO3 humidity sensor at various frequencies is shown in Figure 3a. In the low frequency regions (50 Hz and 100 Hz), it can be seen that the impedance decreases with an increase in frequency and changes by far more than four orders of magnitude with a gradual increase in RH. The sensor presents a higher sensitivity compared with other ABO3-structured semiconductors reported previously, such as SrTiO3 nanospheres, NaTaO3, BaTiO3 [6,8,14]. The high sensitivity is closely related to the N-doping in composite, which induces more oxygen vacancies as an active site to adsorb more water molecules [12]. Figure 4 shows the humidity hysteresis characteristic of the composites between the adsorption and desorption process at 100 Hz. The TiO 2 /SrTiO 3 sensor appeared to have a narrow hysteresis loop. The maximum hysteresis of the device was about 1% RH, which was smaller than that of the pure SrTiO 3 (less than 2% RH as measured). Additionally, at low frequencies, RH has a close-to-linear relationship with impedance, while there is no clear linearity of relationship at high frequencies. A high sensitivity and good linearity can be obtained at 100 Hz. Hence, 100 Hz was chosen as the ideal working frequency. Moreover, the impedance of referent ceramic substrate remained constant w.r.t change in RH, which signifies that the substrate has no contribution in humidity sensing. Figure 3b shows the impedance versus RH curves of sensors based on different samples at 100 Hz. The sensitivity of pure SrTiO3 device changes by about three orders of magnitude while that of black TiO2 changes within one order of magnitude. The gray sample-based sensor exhibited a much higher sensitivity in comparison with that of black TiO2 and pure SrTiO3. The composites composed of different materials usually combine advantages of the components with better properties. For example, In2O3-NiO, ZnO-In2O3 and MoO3-NiO composites all exhibited enhanced humidity sensitive characteristics [5,15,16]. The strengthened moisture properties may be attributed to the improved specific surface area and more active sites in composite. A large surface area-to-volume ratio means that a significant fraction of the atoms or molecules are surface atoms that can participate in surface reactions [15,16]. Figure 4 shows the humidity hysteresis characteristic of the composites between the adsorption and desorption process at 100 Hz. The TiO2/SrTiO3 sensor appeared to have a narrow hysteresis loop. The maximum hysteresis of the device was about 1% RH, which was smaller than that of the pure SrTiO3 (less than 2% RH as measured). The response time is the time taken by a sensor to achieve 90% of the total resistance change in the case of adsorption process or the recovery time in the case of desorption process. Since the humidity detection range primarily covers the range of 11% RH-75% RH, the response and recovery characteristics of the sensor in this range were measured at 100 Hz, as shown in the inset. The response time for the change from 11% RH to 75% RH was about 3.1 s, and recovery time for the change from 75% RH to 11% RH was about 76 s.
To have an enhanced understanding of the sensing mechanism, the complex impedance plots of TiO2/SrTiO3 sensor at different RH are presented in Figure 5 for the frequency range of 40 KHz to 100 kHz. At low RH, only a few water molecules are adsorbed by chemisorption on the active site of the composite surface to form hydroxyl groups. Subsequently, protons would be transferred from the surface hydroxyl groups to water molecules to form hydronium ions (H3O + ) [6]. Though the density of H3O + is low and the transfer of carriers is difficult, the charge carriers would bring about electrons accumulation and bend the energy-band at the grain surface, leading to a decreased resistance. Meanwhile, bounded electrons emerge by means of polarization of the sensing material. At this time, the dominant conducting carriers are H3O + and bounded electrons [17]. The response time is the time taken by a sensor to achieve 90% of the total resistance change in the case of adsorption process or the recovery time in the case of desorption process. Since the humidity detection range primarily covers the range of 11% RH-75% RH, the response and recovery characteristics of the sensor in this range were measured at 100 Hz, as shown in the inset. The response time for the change from 11% RH to 75% RH was about 3.1 s, and recovery time for the change from 75% RH to 11% RH was about 76 s.
To have an enhanced understanding of the sensing mechanism, the complex impedance plots of TiO 2 /SrTiO 3 sensor at different RH are presented in Figure 5 for the frequency range of 40 KHz to 100 kHz. At low RH, only a few water molecules are adsorbed by chemisorption on the active site of the composite surface to form hydroxyl groups. Subsequently, protons would be transferred from the surface hydroxyl groups to water molecules to form hydronium ions (H 3 O + ) [6]. Though the density of H 3 O + is low and the transfer of carriers is difficult, the charge carriers would bring about electrons accumulation and bend the energy-band at the grain surface, leading to a decreased resistance. Meanwhile, bounded electrons emerge by means of polarization of the sensing material. At this time, the dominant conducting carriers are H 3 O + and bounded electrons [17].
Starting from the spectrum of 54% RH, an evident straight line in the low frequency region appears which is the consequence of diffusion and polarization of charged carriers between sensing film and electrodes [18]. With the RH increase, many more water molecules are adsorbed on the surface and tend to form a liquid-like layer, in which a proton transfers between neighboring water molecules. Hence, protons become dominant charged carriers at high RH. Correspondingly, the semicircle in the high frequency region fades away and the straight line in the low frequency region becomes very obvious. Starting from the spectrum of 54% RH, an evident straight line in the low frequency region appears which is the consequence of diffusion and polarization of charged carriers between sensing film and electrodes [18]. With the RH increase, many more water molecules are adsorbed on the surface and tend to form a liquid-like layer, in which a proton transfers between neighboring water molecules. Hence, protons become dominant charged carriers at high RH. Correspondingly, the semicircle in the high frequency region fades away and the straight line in the low frequency region becomes very obvious. It is well known that the characteristic frequency corresponds to the value when the imaginary part of the complex impedance spectrum reaches its maximum, near which is known as the dispersion region. Seen from the spectra in Figure 5, the dispersion region gradually moves toward high frequency as the RH increases, which reveals that the space-charge polarization does exist in the sensor. Based on the research proposed by Paula Vilarinho et al., the dielectric constant of SrTiO3 increases as the frequency increases, then the polarization of adsorbed water molecules is enhanced with increasing RH [19].
Conclusions
In conclusion, the synthesis, characterization, and humidity sensing of TiO2/SrTiO3 were investigated. The impedance changes by more than four orders of magnitude in the range from 11% to 95% RH at 100 Hz, and the maximum hysteresis is about 1% RH. Furthermore, the sensing mechanism was discussed by the complex impedance spectra in detail. These results demonstrate the potential application of the composite in fabricating high performance humidity sensors. It is well known that the characteristic frequency corresponds to the value when the imaginary part of the complex impedance spectrum reaches its maximum, near which is known as the dispersion region. Seen from the spectra in Figure 5, the dispersion region gradually moves toward high frequency as the RH increases, which reveals that the space-charge polarization does exist in the sensor. Based on the research proposed by Paula Vilarinho et al., the dielectric constant of SrTiO 3 increases as the frequency increases, then the polarization of adsorbed water molecules is enhanced with increasing RH [19].
Conclusions
In conclusion, the synthesis, characterization, and humidity sensing of TiO 2 /SrTiO 3 were investigated. The impedance changes by more than four orders of magnitude in the range from 11% to 95% RH at 100 Hz, and the maximum hysteresis is about 1% RH. Furthermore, the sensing mechanism was discussed by the complex impedance spectra in detail. These results demonstrate the potential application of the composite in fabricating high performance humidity sensors.
Figure 1 .
1(a) X-ray diffraction (XRD) patterns of TiO2, TiO2/SrTiO3, and SrTiO3; (b) UV-Visible absorption spectrum of gray TiO2/SrTiO3 composite; Inset is the picture of humidity sensors based on different samples.
Figure 2 .
2The SEM images of TiO2/SrTiO3 composite at low (a) and high (b) resolutions.
Figure 3 .
3(a) Impedance versus relative humidity (RH) curves of TiO2/SrTiO3 humidity sensor at various frequencies; (b) The Impedance versus RH curves of sensors based on different samples.
Figure 1 .
1(a) X-ray diffraction (XRD) patterns of TiO 2 , TiO 2 /SrTiO 3 , and SrTiO 3 ; (b) UV-Visible absorption spectrum of gray TiO 2 /SrTiO 3 composite; Inset is the picture of humidity sensors based on different samples. Sensors 2017, 17, 1310 3 of 6
Figure 1 .
1(a) X-ray diffraction (XRD) patterns of TiO2, TiO2/SrTiO3, and SrTiO3; (b) UV-Visible absorption spectrum of gray TiO2/SrTiO3 composite; Inset is the picture of humidity sensors based on different samples.
Figure 2 .
2The SEM images of TiO2/SrTiO3 composite at low (a) and high (b) resolutions.
Figure 3 .
3(a) Impedance versus relative humidity (RH) curves of TiO2/SrTiO3 humidity sensor at various frequencies; (b) The Impedance versus RH curves of sensors based on different samples.
Figure 2 .
2The SEM images of TiO 2 /SrTiO 3 composite at low (a) and high (b) resolutions.
Figure 2 .
2The
Figure 3 .
3(a) Impedance versus relative humidity (RH) curves of TiO2/SrTiO3 humidity sensor at various frequencies; (b) The Impedance versus RH curves of sensors based on different samples.
Figure 3 .
3(a) Impedance versus relative humidity (RH) curves of TiO 2 /SrTiO 3 humidity sensor at various frequencies; (b) The Impedance versus RH curves of sensors based on different samples.
Figure 4 .
4Humidity hysteresis characteristics of TiO2/SrTiO3 sensor measured at 100 Hz and AC 1 V; Inset shows the response and recovery behavior of TiO2/SrTiO3 humidity sensor.
Figure 4 .
4Humidity hysteresis characteristics of TiO 2 /SrTiO 3 sensor measured at 100 Hz and AC 1 V; Inset shows the response and recovery behavior of TiO 2 /SrTiO 3 humidity sensor.
Figure 5 .
5Complex impedance properties of the composite measured at different RH.
Acknowledgments: The authors are grateful to the National Natural Science Foundation of China (Grant No. 51602273), the Natural Science Foundation of Xinjiang University (BS160218), Thousand Youth Talents Plan (Y42H831301), the Foundation of Director of Xinjiang Technical Institute Physics & Chemistry CAS (2015RC010), Technological Innovation Youth Training Project of Xinjiang Uyghur Autonomous Region (QN2015YX004) for the support to the work. Author Contributions: W.R. and R.W. conceived and designed the experiments; M.Z. and S.W. performed the
Figure 5 .
5Complex impedance properties of the composite measured at different RH.
(
Y42H831301), the Foundation of Director of Xinjiang Technical Institute Physics & Chemistry CAS (2015RC010), Technological Innovation Youth Training Project of Xinjiang Uyghur Autonomous Region (QN2015YX004) for the support to the work.
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Conflicts of Interest:The authors declare no conflict of interest.
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| A simple flexible metal oxide (γ-Al 2 O 3 ) film based parallel plate capacitive humidity sensor has been fabricated by sol-gel method on UPILEX-S polyimide substrate for measuring relative humidity (RH). The important features of the sensor are easy to fabricate, no shorting problem, highly flexible, bulk producible and can be integrated with signal conditioning unit. The characteristics of the sensor have been studied with humidity in the range of 5 to 85 % RH. The measured sensitivity of the sensor is 4.044 pF/% RH The sensor output is found to be highly stable and reproducible up to 0.4% The response and recovery time are 244s and 159s respectively. | A solid membrane electrode selective to sulfate ion was prepared from barium chloranilate (CLB) with poly(vinyl chloride) (PVC). The electrode exhibited sub-Nernstian response within the sulfate ion concentration range 10 -110 -4 mol dm -3 at pH range of 47. The membrane electrode showed good selectivity to sulfur ion and was applied to determine sulfur in polymer and sulfate ion in seawater. | Nanocrystalline BaTiO3 particles modified with polarizable ligands were synthesized through hydrolysis of modified metal–organics below 100°C. BaTiO3 precursor was synthesized from barium metal, titanium isopropoxide and polarizable ligands in a mixture of ethanol and 2-ethoxyethanol. The modified Ba–Ti complex alkoxide was hydrolyzed yielding BaTiO3 particles modified with organics. The crystallinty of nanometer-sized particles was dependent upon the hydrolysis conditions, and increased with increasing water amount and time. The nanocrystalline particles were identified to be BaTiO3 by X-ray diffraction (XRD) and electron diffraction. A fluid consisting of modified BaTiO3 particles and silicone oil revealed a typical electrorheological (ER) behavior on applying DC field. The ER behavior was found to depend upon the kind of ligand. 4-Fluorobenzyloxy modifier revealed the highest yield stress in the ER measurement among 4-substitued benzyloxy ligands examined. | In this paper, temperature and humidity sensors with dimensions less than $1 \times 1$ mm2 are printed together on a flexible polyimide substrate to create a miniaturized sensing circuit. The humidity changes (RH 35%–95%) are detected by capacitance change of the printed Nafion thin film, while the temperature variation (15 °C–80 °C) can be detected by the resistance change of the printed NiO thin films. The two micro sensors are printed over a flexible substrate to create an RC circuit for simultaneous detection of temperature and humidity. An equivalent circuit model is also developed to describe the performance of the combined sensing device in a wide range of relative humidity and temperature range. This printed sensing device shows great sensitivity and response times and can be applied in environmental monitoring applications. | Taking Ba(OH)2 solution as eletrolyte,alternative current(AC) and direct current(DC) power microarc oxidation(MAO) technologies were used to deposite BaTiO3 films on industrial pure titanium plate,and the phase composite,surface morphology and ferroelectric properties of the films were characterized.The results show that the films deposited by DC /AC power microarc oxidation were mainly composed of tetragonal and hexagonal BaTiO3 phase,respectively.Holes with diameter of hundreds of nanometer to a few microns and cracks distributed uniformly on the films surface.The BaTiO3 film with hexagonal phase had not ferroelectric properties until it was annealed at high temperature for a long time,and the ferroelectric BaTiO3 film could be prepared directly by DC power microarc oxidation technology. | 1,999,786 | Abstract Humidity sensing composite material is made of nanocrystalline BaTiO3 and polymer polystrene sulfonic sodium (PSS). The composite material is spin-coated onto a ceramics substrate to fabricate humidity sensor. The electrical properties of the sensor are measured. The resistance verse the relative humidity (RH) of the sensor enjoys good sensitivity and linearity in the range of 33–98%RH. The capacitance and the impedance of the sensor change with different frequency and RH. The frequency ranges from 20 Hz to 100 kHz in the plots. Complex impedance plots are semicircles at low RH and a semicircle connected with a line at high RH, respectively. The different kinds of the impedance plots represent the different sensing mechanism for the composite material BaTiO3/PSS humidity sensor. | REVIEW Humidity Sensors: A Review of Materials and Mechanisms | Ultrafast Response Humidity Sensor Based on Electrospun Porous BaTiO3 Nanofibers | TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity | A real-time humidity sensor based on a microwave oscillator with conducting polymer PEDOT:PSS film | A gray TiO 2 /SrTiO 3 composite nanocrystalline sensor with narrow band-gap was successfully prepared through a facile wet chemical method. The precursor was calcined in N 2 flow under atmospheric pressure and thereafter, a humidity sensor based on the composite was fabricated. The sensor showed high resistive sensitivity and varied by more than four orders of magnitude with an increase in relative humidity (RH) from 11% to 95%. The response and recovery time were about 3.1 s and 76 s, respectively with maximum hysteresis at 1% RH. In comparison with pure SrTiO 3 and black TiO 2 , the gray composite based device exhibits a higher sensitivity. These results demonstrate the potential of gray TiO 2 /SrTiO 3 for humidity sensing applications. | A low-power, wide-dynamic-range integrated humidity sensing chip is implemented using a printable polymer sensing material with an on-chip pulse-width-modulation interface circuit. By using the inkjet printing technique, poly(3,4-ethylene-dioxythiophene)/polystyrene sulfonate that has humidity sensing features can be printed onto the top metal layer of a 0.35 μm CMOS IC. The developed printing-on-chip humidity sensor achieves a heterogeneous three dimensional sensor system-on-chip architecture. The humidity sensing of the implemented printing-on-chip sensor system is experimentally tested. The sensor shows a sensitivity of 0.98% to humidity in the atmosphere. The maximum dynamic range of the readout circuit is 9.8 MΩ, which can be further tuned by the frequency of input signal to fit the requirement of the resistance of printed sensor. The power consumption keeps only 154 μW. This printing-on-chip sensor provides a practical solution to fulfill an ultra-small integrated sensor for the applications in miniaturized sensing systems. | Autonomous soil moisture sensor based on nanostructured thermosensitive resistors powered by an integrated thermoelectric generator | Humidity Sensing by Polymer-Loaded UHF RFID Antennas |
1,999,787 | Looks great. Gives off a decent amount of heat | Looks great but does not heat up very well will have to return- | Doesn't give off heat. It just looks nice. Wouldn't buy it again. | Looks great. The heat is not as effective as it could be because the heat output is on the top facing up, so while the ceiling area above the heater gets warm the space in front of the heater not so much. | Looks and works great. I use this to help take the chill out of a seasonal sun porch. It's effective.
We have a number of Lasko heaters in our home, we get a lot of use out of them and have had no problems. | i haven't used the heater yet, it's summer here but i like the looks of it. | I would like to say a BIG Thank you! The heater is Great! I love it. Your timing was perfect. I will be looking and purchasing in the future.
Thank You!!
Warren A. Hamer II | It looks good and fills the void of an empty fireplace. Does not heat well. Sort of expected that from many of the reviews. | Very nice.
Works perfect with lower temperatures.
Has a nice bag to storage that protects it from dust and grime. | 1,999,787 | Box came was delivered broken. Otherwise all the pieces inside were intact. Hex screws were cumbersome. But that was the most difficult part of esembling. Looks great. Gives off a decent amount of heat. Dont rely on it warming up an entire room. | The box came damaged but the goal was fine and fairly easy to assemble | The box arrives with wood glue and everything just for you to waste your time assembling a nightmare | The packaging was a bit iffy but I do not care as all parts purchased were in the box and as I said before it was easy to assemble | Product arrived used from warehouse without any screws. Product ... | be careful screws strip real easy try not to over turn but the box is ... | ... ships in several screw together sections but it's very easy to assemble | Damaged box and missing parts | We were shipped wrong parts but that was taken care of right away which was really great. The supports for the main bed also don |
1,999,788 | This is a very flimsy doormat and retains a lot ... | VERY NICE PRODUCT, STURDY DOOR, USED IT FOR A CERAKOTE OVEN TO CURE PAINT PROJECTS. I WOULD LIKE TO GET ANOTHER ONE FOR THE BEDROOM. | Had it for two days and the door was not very sturdy. It broke and can't return it back. Might cost me more to return than fix. I will never buy this kind again. | I used to have a doormat and it needed replacing and I was not able to locate this in any of the stores. I was able to find this on Amazon.com and was extremely pleased to find this. I resembles my previous doormat and I couldn't be more happy for finding a replacement. | This is the best it could be. We have a 200 pound recycled wood door, its smooth as silk. It's made in the USA!! | Im saying I only like this instead of love it because is only fits on modern day, thick doors. I bought this for my antique front door and it wouldn't stay as the door was much thinner than modern day doors. I ended up using it on my door, which is fine, but not what I intended it for. Super easy install and seems to keep the seam tight. | We bought this as a spare for our camper door, as it seems so fragile. Wanted to have it on-hand in case ours breaks while traveling. Wish they were metal and stronger. | Overall the door is solid and has worked well in our large sliding glass door. Only problem was that it did not come with enough of the foam that you place between the pet door and the slider so I had to go buy my own to create the full seal. Other than that it has worked great. | This is an excellent strong doorstop. Much better than the ones on springs. I switched out all the ones that were installed by the builder of my home. | 1,999,788 | This is a very flimsy doormat and retains a lot of water. No near as clean and crisp as the picture indicates. Not worth the money. | This is NOT as pictured. NOT Intensive Clean Plus, but the red flap version! | I've remodeled my kitchen and like the clean look | Looks great on walnut door | *high* quality, exterior door sweeps | It's pretty and blends in well with the my bathroom | ... very clean floor it picks up particles and looks dirty. It also is very difficult to clean because ... | Excellent product...easy to clean and keeps the water fresh and cold. | The finish on this is nice and cleans easily |
1,999,789 | Everyone I've shared them with truly like what Mike has to say | I mean, I enjoy them all, but I relate to Mike the most (except the MLP stuff, but hey, to each his own). | Every week there are several good football game albums on Flickr, would anyone like to have a thread where these can be shared?
For example my album from the game
I'll talk with some of the photographers and see if they are ok with having their photos shared here (or if they see this post first). But some of them won't have their albums up until tomorrow. | Hey! just saw an older post on here talking abt a MIKE loosie comp and figured id post mine, if anyone has anything im missing please link me im always excited to find out about old MIKE tracks that have been lost.
heres the tracklist for both
heres the link and the key is #Bh5YwunLJEg2J1(MIKE)fUUVFe1w (remove "(dot) and replace it with an actual dot for the link and just remove "(MIKE)" from the key for it to work, im doing this cos reddit just likes marking posts with mega links as spam for some reason)
Stay safe n have a good one <3 | Fat Mike did an interview with NME and mentioned how they have a new song that Avenged Sevenfold play on.
>Ever had any other responses from the musicians you’ve mentioned in your songs?
>“I don’t know, but after talking shit about Avenged Sevenfold for years, I played golf with their singer Matt Sanders yesterday, and we get on great. We have a new song they play on. That’s a funny marriage of two bands, but it works – unlike most metal bands, they’re sweet guys, and not full of themselves.” | His honesty is honestlly is unbelievable Michael's lyrics come directly from his hear and soul. Mike makes you, the reader, feel immediately as a part of hi own family! He portays himself a very down to earthperson,, the guy next door type . This is a wondeerfully refreshing side of a musician's life, and how God puts people in our lives for a reasson. | I put that poem to music back then and it's stayed in my regular performance rotation ever since. Recently I had it professionally recorded.
Rule 1#: Posts must be relevant to Radiohead, its members, or their side-projects.
I understand if this doesn't sit well with posting rules. But I wanted to share the recording, as it's a personal landmark of my love affair with the band and it's fans.
[The original post.]
( | We all make awesome arguments that we are proud of. We should show them off.
Comment your best argument this week!
Or, if you just read an argument that you felt was mic drop worthy, you are free to share that as well!
Feel free to use the prolife comment the response was addressed to, if there is one. Just be sure to leave out the
username. | Welcome to the Track of the Week thread, where a song produced by ya boy Sonny is randomly selected and put up for discussion.
This weeks track is: **Skrillex - Scatta**.
Here you can discuss anything you like about the track; where you first heard it, what it means to you, details about the production that stick out to you, etc. You are also invited to post any live set footage of the song, remixes of the song, random factoids; anything of the sort relating to the selected song!
Please remember to keep the discussion civil and follow the subreddit rules at all times. | 1,999,789 | Had bought 4 copies and given away two. Everyone I've shared them with truly like what Mike has to say. Was blessed to see him in person once and he "really speaks to me". Read him every morning on my computer. TUT...starts my day with messages that are uncanny and fit exactly what I need. | mark has a wonderful voice that delivers a message | I bought a few copies as requested by my husband ... | I loved "Conversations". Purchased copies to give as gifts to ... | and I wasn't disappointed. His message is simple and prompts personal reflection ... | Mike writes a great book - straight forward | ONE OF THE BEST I HAVE EVER READ HAVE BOUGHT 10 PLUS COPIES ... | This was a great purchase! I am a Speech and Language Therapist ... | glad to have electronic copy for |
1,999,790 | Sleep and the impact of caffeine, supplements, and other stimulants | Caffeine (particularly in the form of coffee) is one of the most widely consumed stimulants in the world, with 90% of American adults consuming caffeine-infused beverages almost daily. While there is substantial evidence that caffeine enhances performance, caffeine withdrawal leads to deficits at both the individual (eg, cognitive, emotional, and behavioral processes) and societal (eg, increases in work accidents) level. Scholars for some time have considered that the supposed psychoactive benefits of caffeine may be the result of the mere reversal of deleterious effects of caffeine withdrawal, rather than a net benefit of caffeine ingestion. In this integrative review, we examine evidence illuminating the relationship between caffeine consumption and subsequent quality and quantity of nighttime rest. Secondly, we consider evidence as to whether performance deficits caused by sleep deprivation linked to caffeine can be reversed by caffeine consumption during the subsequent daytime period. Finally, we consider how these two stages can be reconciled in a single model that enables calculation of the net caffeine effect on daytime functioning. The literature highlights a range of positive impacts of caffeine consumption on both physical and cognitive functioning. There are also a number of factors that complicate any conclusions that can be drawn regarding the potential of caffeine to improve performance. Most critically, performance improvements the next day may simply be a result of the reversal of caffeine withdrawal. Animal studies and well-controlled human studies involving high habitual and low habitual users tend to confirm a "net benefit" for caffeine use. Further research, particularly with (necessarily rare) caffeine-naive populations, is required to elucidate the complexities of the relationship between caffeine, sleep, and daytime functioning. However, the convenience of accessing caffeine compared to ensuring adequate restorative sleep means that caffeine has applied advantages that are likely to see its use as a performance "enhancing" substance persist. |
Introduction
Numerous different foods and beverages contain the alkaloid caffeine, including coffee, tea, cola, ice tea, chocolate and energy drinks, which makes caffeine the most commonly ingested psychoactive drug worldwide [1]. Caffeine is a non-specific, competitive antagonist of adenosine receptors [2]. Adenosine effects on these receptors include the up-regulation of A1 receptors and the increase of adenosine inhibition, which reduces excitatory neurotransmission, and alertness affecting sleep homeostasis [3]. The best-established marker of the homeostatic regulation of sleep is deep sleep slow-wave activity (SWA; 1-4.5 Hz) in the electroencephalogram (EEG) [4,5]. SWA is tightly coupled to prior wakefulness duration [5] and results from highly synchronized activity of cortical neurons [6]. Caffeine is considered to powerfully stimulate our brain networks during waking and sleep.
How caffeine affects sleep regulation has primarily been investigated in adults [7][8][9]. These studies show that even low doses of caffeine impact the build-up of sleep pressure by reducing SWA at the beginning of the night in adult populations. These studies also show that SWA is affected by caffeine intake that directly precedes sleep [8] or that is consumed in the morning of the same day preceding sleep [9]. Stimulant effects of caffeine in adults also include alterations in sleep continuity (i.e., reduced sleep efficiency and increased sleep latency) [8,10]. While these studies show that caffeine strongly affects mature sleep brain physiology, no comparable studies exist during sensitive periods of brain development [11] (i.e., in childhood or adolescence).
Caffeine consumption has significantly increased among adolescents over the past years [12]. Similar to adults, high caffeine intake in adolescents is associated with an increase of reported sleep difficulties, sleep disturbances, and morning tiredness [13,14]. One emerging question is whether high caffeine consuming children and adolescents exhibit a concomitant reduction in objective sleep quality. Furthermore, considering the growing consumption frequency of caffeine in adolescents worldwide, it is surprising that no studies have objectively quantified effects of caffeine [8,9] in children and adolescents through the gold-standard measure of sleep quality, i.e., EEG activity. Addressing this gap in knowledge becomes particularly relevant given that a growing body of epidemiological literature reports early sleep difficulties as predictors for later psychological, emotional and social problems [15][16][17]. The aim of the present study was to investigate the effects of high caffeine consumption on sleep physiology and associations with sleep habits in young life.
Materials and Methods
Participants and Scheduling
Participants were recruited using paper and personal advertisement in schools, football clubs, boy scouts and through personal contact. Approximately 800 adolescents were handed a flyer, telephone screenings were completed with 50 adolescents, and 32 subjects were finally included in the study based on exclusion / inclusion criteria and personal interest to participate. Participants were aged 10.0 to 16.9 years, with 16 of the subjects (8 males, 11.9-16.8 years) reporting a habitual consumption of at least two servings of caffeine per day throughout the duration of at least the past three years. A standardized in-laboratory screening telephone interview was performed to obtain and evaluate habits of caffeine consumption and sleep. Caffeine consumers were contrasted with 16 healthy age-and gender-matched control subjects, who denied regular habitual caffeine intake. Although most caffeine consumers affirmed caffeine intake both in the morning and evening, no sleep difficulties were reported. For all subjects, exclusion criteria were smoking, alcohol consumption, sleep disturbances and travelling across more than two time zones within the six months prior to the assessment. The institutional review board of the cantonal ethic commission Zurich (Switzerland, Study identification number EK StV 27/07) approved the study, and the study was performed according to the Declaration of Helsinki. Written informed consent was obtained from participants and parents. Sleep assessments for females were scheduled during their follicular phase of the menstrual cycle, when sleep quality is increased compared to premenstrual and menstrual phases [18]. All sleep assessments took place at the University Children's Hospital Zurich (Zurich, Switzerland).
Actigraphy, Sleep Diary and Questionnaires
During one week prior to the assessment, participants followed a stabilized bedtime schedule that was verified with wrist actigraphy and bedtime diaries. In addition, reports on foods and beverages that contain caffeine, as well as the time of consumption were obtained during this week. Subjects were advised to consume caffeine according to habitual use. Reports together with the screening questionnaires, served as quantitative measures for frequency and amount of caffeine intake. The exact caffeine content of all reported products was obtained from the manufacturers' declarations, and caffeine content of roasted and ground coffee provided the basis for all "coffee" reports [19]. Pubertal rating was assessed with a self-administered rating scale for pubertal development, which shows reasonable internal consistency and reliability (0.67-0.70 Cronbach's coefficient alpha) [20]. Yet pubertal rating was not used as matching variable between groups, due to age being a stronger predictor for maturational changes in the EEG than pubertal status [21]. In addition, socioeconomic status (SES) [22] and chronotype [23] were assessed. Chronotype shows good consensus with the Morning-Eveningness Questionnaire [24] and the Composite Scale of Morningness [25], and is thus a valid estimate of a subject's circadian preference. SES quantifies school education of the mother and professional position of the father and is a marker for the family's relative social and economic position. SES has been validated, showing adequate reliability in our community (e.g., SES correlates with intellectual and language outcome of children) [22].
In the morning following the sleep assessments, subjects rated their morning tiredness using a visual analogue scale (VAS). VAS entailed a line with endpoints marking the two extreme of the category (i.e., relaxed vs. tired). Subjective ratings along the line were converted into a percentage value ranging from 0% to 100% for analysis.
Attention Task
The attention task was performed after waking up from the recording night. Subjects gazed at a white cross on a black background on a computer screen while listening to 300 regularly presented acoustic stimuli (around 80 dB, 880 Hz) during four minutes. Ten percent of these stimuli were randomly presented deviants in frequency (988 Hz). Participants were instructed to react as quickly as possible to the deviant stimuli with a mouse click. MATLAB (Mathworks, Natick, MA, USA) was used for task presentation and the calculation of the attention variable "reaction time" (time elapsed between presentation of stimulus and mouse click).
Sleep Assessment
Sleep assessments involved hdEEG, electromyogram (two chin electrodes) and electrooculogram, were scheduled according to individually reported habitual bedtimes, and all participants were awoken in the morning according to a scheduled wake-up time. In the caffeine group, 5 subjects were assessed on weekend nights (Friday through Sunday morning), and 11 on weekday nights, in the control group 4 assessments took place on weekend nights and 12 on weekday nights. Electrode nets with 128 channels (HydroCel Geodesic Sensor Net for long-term monitoring, EGI) were adjusted to Cz and mastoids and filled with gel electrolyte, which ensures maintenance of good quality signals even after several hours of recording. Impedance level was set below 70 kΩ and the signal was referenced to Cz for direct visualization (re-references to the average across all channels, details follow) with a sampling rate of 500 Hz, and then off-line bandpass filtered (0.5-50 Hz), and down sampled to 128 Hz. Sleep stages were visually scored in 20 s epochs according to standard criteria [26]. Semi-automatic artefact correction was performed based on two frequency bands (0.75-4.5 Hz and 20-30 Hz, see [27]). As in previous studies [28,29] only the 109 derivations located above the ears were included for analysis (to avoid artifacts via facial and neck muscles) and all derivations were re-referenced to the average across all electrodes. Using a standard approach [28,30] a fast Fourier transform routine was performed (FFT, Hamming window, average of five 4-s epochs), log-transformed average power spectra (resolution of 0.25-Hz-bins) were calculated for group comparisons, including non-rapid eye movement sleep (NREM) sleep stages 2 and 3. Analyses were performed using MATLAB (Mathworks, Natick, MA, USA) and SPSS (IBM). For topography analysis, EEG power for each electrode was plotted on the planar projection of the scalp using the topoplot function of the MATLAB EEGLAB toolbox [31].
Statistics
We verified normality of data distribution using nonparametric Kolmogorov-Smirnov test for one sample (comparison to an expected distribution), and homoscedasticity was examined with Levene's test. For group comparisons, two-tailed, unpaired Student's t-tests (for normally distributed data) or Mann-Whitney-U tests (for not normally distributed data) were calculated. Where homoscedasticity was not met, the p-value corrected for lack of homogeneity of variance is included. We corrected for multiple comparisons using false discovery rate (FDR). For power analysis, group means were compared using a two-sided equality test. An effect size of 80% and an alpha level of 0.05 was chosen. Significant topographical differences were assessed by statistical nonparametric mapping (SnPM), using single threshold tests [32]. As in our previous work [33,34], we calculated t-values for each electrode, found the maximal t-value across all electrodes for each permutation, and determined the t-value threshold as the 95th percentile of the permutation-derived t-values. Electrodes exceeding this threshold were considered significant regarding topographical group differences.
Results
Demographic Characteristics
Caffeine consumers and controls did not differ in age, weight, Tanner stage, chronotype, or SES ( Table 1). As expected, caffeine intake per day as well as caffeine intake controlled for body weight differed clearly between caffeine consumers and controls. Table 1, reports scores (M ± SEM) for the caffeine consumers and the controls. Number (n) of subjects missing is indicated with footnotes (n). (f = female; m = male). Significant differences are indicated with asterisk (* p < 0.05, two tailed, unpaired Student's t-test).
Sleep Diary, Architecture, Subjective Records and Attention Task
Sleep diaries showed that caffeine consumers went to bed 57 min later (Caffeine 23:14 ± 11 [clock time ± min], Control 22:17 ± 15) and spent 53 min less time in bed (Caffeine 08 h 10 min ± 13 min, Control 09 h 03 min ± 16 min) compared to the control group ( Table 2). The difference of time in bed between weekend-days (nights from Friday to Saturday and from Saturday to Sunday) and week-days did not vary between groups (Caffeine 01 h 03 min ± 19 min, Control 01 h 18 min ± 21 min). The time of latest caffeine consumption was reported as 16:37 ± 00:46 (average across days). Participants slept well during the recording night (> 89% average sleep efficiency in both groups, Table 2) and showed no group difference in sleep architecture (Table 2). Neither subjectively reported tiredness in the morning nor an objective measure of tiredness (reaction time in an attention task) differed between groups (Table 2). No relationship was found between morning tiredness and Tanner stage. Table 2, Sleep parameters are indicated as M ± SEM, sleep architecture was taken from visual scoring and relative values are calculated for each subject separately and then averaged for groups. Diaries and reports about the last caffeine consumption refer to reports during the week prior to the assessments. In the EEG, sleep onset latency refers to the first occurrence of stage 2 sleep. Subjective statements about morning tiredness were reported directly after the recording session. Reaction time in the attention task was averaged across all behavioral responses. Significant group differences are indicated with asterisk (* p < 0.05; two-tailed, unpaired Student's t-test). Power analysis indicates minimal group size required to obtain a significant result (comparison of group means, 2-sided equality test, effect size 80%, alpha level 0.05).
EEG Power
In the first 2 h of NREM sleep absolute EEG power was lower in caffeine consumers compared to control subjects, encompassing large frequency bands within SWA (1-4.5 Hz), and alpha (8.25-9.75; Figure 1). We calculated SWA across the night to investigate the persistence of this effect and found that group differences disappeared by the morning (Figure 2). This EEG power convergence also occurred in alpha activity. Because overall group differences were most prominent in early sleep and low frequencies, we then focused on the SWA frequency range in the first two hours of NREM sleep for further analyses. for the first and last two hours (latest possible artifact-free, common two hours among all subjects) of NREM sleep stages N2-3. The asterisk indicates a significant difference between caffeine consumers and controls in the first two hours of NREM sleep (p < 0.05, two-tailed, unpaired Student's t-test).
SWA topography appeared fairly symmetrical between hemispheres for both groups (Figure 3) with local maxima and minima in line with previous studies, e.g., [28]. Group differences prevailed over wide areas, showing lower SWA in caffeine consumers: SWA was significantly reduced in 33% of all electrodes with an average reduction of 20% ± 9% across all electrodes and subjects. Largest effects predominated over prefrontal, central and occipital regions (Figure 3). Topographical comparisons of alpha activity also revealed group differences that were pronounced in similar areas, such that caffeine consumers exhibited reduced power over prefrontal, central, parietal and occipital regions (Figure 3). . Upper panels show the topographical distribution of SWA averaged for the two groups in NREM stages 2 and 3 during the first two hours of NREM sleep, group differences and the level of significance (t < −2.21, two-tailed, unpaired t-test). Lower panels show the topographical distribution of alpha activity averaged for the two groups in NREM stages 2 and 3 during the first two hours of NREM sleep, group differences and the level of significance (t < −2.25, two-tailed, unpaired t-test). The significance level is indicated with a red arrow. Values are color coded (maxima in red, minima in blue, respectively maxima in white, minima in black for t-values) and plotted on the planar projection of a hemispheric scalp model. Maps for caffeine consumers and controls are presented using the same color scale, and statistical maps are proportionally scaled to optimize color contrast. Values between electrodes were interpolated in each plot.
Discussion
We report effects of regular caffeine consumption on sleep behavior and brain activity during sleep in children and adolescents. In particular, we examined whether caffeine consumption is associated with altered sleep habits and brain activity during children's and adolescents' sleep as reported in adults [8,9]. First, our findings show that regular caffeine consumption in young subjects is associated with later bedtimes and shorter time in bed. Second, caffeine-consuming subjects reveal reduced SWA and alpha activity with strongest effects over prefrontal, central and occipital regions. Finally, the SWA reduction appears mostly at the beginning of the night, which is consistent with findings in adults [8,9]. Our results suggest that only minor changes occur in sleep architecture (i.e., sleep stages) and continuity and that regular caffeine consumption in adolescents may lead to later bedtimes and reduced sleep depth, as measured by SWA.
In adults, caffeine attenuates the build-up of sleep SWA during the day [8,9] and thus reduces sleepiness. We consequently expected later bedtimes in young caffeine consumers, which was confirmed with the sleep diary data. Diaries were shown to be a tool equally reliable to actigraphy for the assessment of sleep (bedtimes, sleep start [35]). At what time of the day caffeine was consumed was variable across subjects (e.g., see variability of latest caffeine intake, Table 2), which may have contributed to individual differences in the effects of caffeine. Because habitual rise times did not differ between groups, the question arises whether caffeine consumers are chronically sleep restricted, which would increase tiredness and other symptoms associated with sleep loss, such as impairment of working memory or inhibitory control [36][37][38]. We assumed that subjective statements about morning tiredness are a reliable inverse measure for being well rested, and similarly a short reaction time in the attention task. It is interesting that these measures did not differ between groups, which may imply that daily functioning is not affected by caffeine consumption. However, as our power analysis indicates (Table 2), larger samples may reveal additional group differences. It is conceivable that the shortened time spent in bed may increase caffeine intake throughout the subsequent day to combat daytime sleepiness [39]. Other studies, however, have reported increased morning tiredness in high caffeine consuming adolescents, compared to controls [13]. However, caffeine consumption in terms of exact volume has not been computed in that study and a different quantification of subjective tiredness was used, a caveat when directly comparing outcomes between studies. It will be relevant in future studies to track daytime sleepiness throughout the day and examine interactions between sleepiness and acute caffeine intake. On the other hand, if caffeine consumers were chronically sleep deprived, they might have underestimated subjective tiredness, because sleep restricted adults are largely unaware of increasing cognitive deficits [37].
Alpha activity revealed topographical effects similar to SWA when contrasting caffeine consumers with the control group. A close relationship between alpha and SWA is an often-observed phenomenon (i.e., "alpha-delta") that is characterized as alpha waves superimposed on slow waves [40,41]. The alpha-delta relationship has been discussed in the context of the perception of sleep depth and the estimation of sleep time, however with controversy in the literature [40]. Our finding that alpha and SWA group differences were topographically similar further supports the alpha-delta link, but it remains to be investigated whether reduced alpha power in caffeine consumers accounts for perceived sleep quality and duration in children and adolescents.
The stimulatory effect of caffeine is central. The action of the adenosine antagonist affects mainly sleep quality and the cardiovascular system [1]. By doing so, caffeine modulates the cAMP signaling pathway [2], which plays a key role in neural function [42]. Adenosine accumulation, on the other hand, was suggested to prevent neurodegeneration [43]. It is thus likely that caffeine affects neuronal plasticity. Numerous studies illustrate the importance of sleep SWA for neuronal plasticity [44,45] and the caffeine induced reduction of SWA may affect synaptic plasticity during cortical maturation. Alternative pathways of action are also conceivable: Caffeine may impact plasticity via microglia, which play a key role in synaptic pruning [46]. Chronic caffeine ingestion impacts microglia morphology and density [47]. A further potential interference of caffeine with synaptic plasticity might originate from the blocked activation of the actin binding protein Cofilin, which is central for synaptic plasticity mechanisms [48]. No matter what mechanisms underlie the impact of caffeine on plasticity, further research is needed to understand whether and how caffeine consumption throughout the critical period of adolescence may ultimately alter cortical maturation.
Finally, our findings are also of practical relevance in the on-going discussion about adjusting school start times to adolescent's needs [49]. Given that rise times are determined by school schedules, later school start times may allow caffeine consumers to be comparably well rested through compensating for later bedtimes and potentially worse sleep quality (increased subjectively reported and objectively measured wakefulness after sleep onset). Conversely, one problem of this view is the fact that caffeine consumers do not seem to compensate for reduced time in bed with increased sleep duration at weekends (no difference of time in bed between week days and weekend days). Thus, sleep need might generally be reduced in caffeine consuming children and adolescents. Additional support for this hypothesis comes from our finding that caffeine consumers exhibit reduced SWA, the best-established physiological marker of sleep need [50]. SWA levels at the beginning of the night were lower in caffeine consumers compared to controls, but converge to equivalence in the morning hours. This convergence is in line with the subjective perception of groups being equally rested (no group difference in "tiredness"). However, considering that sleep is involved in plastic processes of neural networks [51], it remains to be examined whether such an adaptive response to caffeine consumption that results in reduced sleep, affects development. Alternatively, we cannot exclude the possibility that children and adolescents with less deep sleep and a lifestyle involving later bedtimes have more social demands and are more prone to consume high amounts of caffeine [52]. These data are critical for gaining insight into the possible vulnerability of the developing brain through extensive caffeine consumption. Additionally, it is possible that caffeine consumers exhibit a reduced capacity for the state of deep sleep related to cortical hyperarousal, which can be induced through caffeine [53]. Yet, we did not find group differences in wake after sleep onset, nor did we find increased beta activity, which was proposed to reflect a cortical hyperarousal in the context of insomnia [54]. However, these findings need to be interpreted in the context of limitations. The cross-sectional nature of the data and the rather small sample size does not allow developmental conclusions and limits the statistical power of our study. Further, the nature of the study design does not allow to address causality, and prospective examinations are required that investigate mediators that may be driving the correlation between caffeine consumption and sleep (e.g., social context, lifestyle, time point of caffeine intake). However, because no correlative relationship was found between bedtime and the individual extent of SWA, it is unlikely that bedtime has caused the effect of reduced SWA in a homeostatic manner.
Conclusions
In summary, this study shows that regular caffeine consumption in children and adolescents is associated with later bedtime and affects brain activity during sleep similar to adults. Because childhood and adolescence are sensitive periods of neural network refinement processes, where sleep may play a prominent role [53], longitudinal and experimental studies will provide clarity on whether intensive caffeine consumption can alter neurodevelopmental trajectories as reported in animals [55].
Figure 1 .
1Power spectrum of the sleep electroencephalogram (EEG) in caffeine consumers (red, n = 16) and controls (blue, n = 16). Group-wise comparisons were performed with the first two hours of NREM sleep EEG data using the average across all 109 electrode channels for each subject within each frequency bin within 0.25 and 25 Hz. Commonly used EEG frequencies are separated by vertical lines: SWA = 1-4.5 Hz; theta = 4.75-7.75Hz; alpha = 8-9.75 Hz; beta = 20-25 Hz. Frequency bins (0.25-Hz) within which power differed significantly (p < 0.05; two-tailed, unpaired Student's t-test) and the level of their significance are shown in the lower panel, only significant p values (after FDR correction) are plotted.
Figure 2 .
2Slow-wave activity (SWA) across the night in caffeine consumers (red, n = 16) and controls (blue, n = 16). SWA (1-4.5 Hz) was averaged across all electrodes (M ± SEM)
Figure 3 .
3Regional sleep slow-wave activity (SWA, 1-4.5 Hz) and alpha activity (8.25-9.75) in caffeine consumers (n = 16) and controls (n = 16)
Table 1 .
1Demographic characteristics of the caffeine consumers and the controls.Caffeine Consumers (n = 16)
Controls (n = 16)
Age (years); [f, m]
14.5 ± 0.4 (11.9-16.8);
[15.1 ± 0.6, 14.0 ± 0.4]
14.4 ± 0.4 (11.8-16.4);
[15.0 ± 0.5, 13.8 ± 0.5]
Caffeine consumption
(mg/kg/d)
2.5 ± 0.4 *
0.1 ± 0.0 *
Chronotype
4.3 ± 0.2
3.8 ± 0.2
Socio Economic Status, SES
5.0 ± 0.5 (5)
3.8 ± 0.3 (7)
Sex (f, m)
8 f, 8 m
8 f, 8 m
Tanner puberty scale; [f, m]
7.7 ± 0.7 (3) ; [8.4 ± 1.3, 7.9 ± 0.9]
7.5 ± 0.6 (2) ; [7.7 ± 1.1, 7.4 ± 0.7]
Weight (kg)
52.3 ± 2.6
51.2 ± 3.7 (6)
Table 2 .
2Sleep diary, architecture, continuity, subjective reports and attention task.Data
Point in time
Sleep Variables
Caffeine
Consumers
(n = 16)
Controls
(n = 16)
Estimated n
to Reveal
Group
Difference
Diary
Week prior
Rise time (hrs:min)
07:29 ± 7.6
07:20 ± 7.5 °
170
Bed time (Lights out) (hrs:min)
23:14 ± 11.4 * 22:17 ± 15.4 °
13
Time in bed entire week (hrs:min)
08:10 ± 0:13 * 09:03 ± 0:16 °
18
Time in bed week days (hrs:min)
08:07 ± 0:19
08:28 ± 0:10
120
Time in bed weekend days (hrs:min)
09:04 ± 0:16
09:42 ± 0:27
81
Difference time in bed weekend-days
and time in bed weekdays (hrs:min)
01:03 ± 0:19
01:18 ± 0:21
342
Last caffeine consumption (hrs:min)
16:37 ± 00:46
n.a.
n.a.
Sleep architecture
and continuity (EEG)
Night
of assessment
Time in bed (hrs:min)
07:48 ± 15.4
08:10 ± 16.7
157
Total sleep time (hrs:min)
06:59 ± 0:15
07:39 ± 0:18
44
Sleep onset latency (min)
20.3 ± 4.1
15.8 ± 1.8
108
Wakefulness after sleep onset (min)
32.1 ± 6.7
17.6 ± 2.5
26
Stage 1 (% of total sleep time)
6.8 ± 1.3
5.8 ± 0.6
221
Stage 2 (% of total sleep time)
48.6 ± 1.4
49.1 ± 1.9
2689
Slow-wave sleep
(% of total sleep time)
27.2 ± 2.0
24.1 ± 1.8
91
REM sleep (% of total sleep time)
17.5 ± 1.0
20.2 ± 1.7
62
Sleep efficiency
(total sleep time/time in bed) (%)
89.6 ± 1.9
93.7 ± 0.6
24
Subjective
reports/attention task
Morning
after assessment
Reaction time in attention task (ms)
283.6 ± 8.4 °°287.9 ± 7.9 °°
733
Subjectively reported morning
tiredness (relaxed vs. tired) (%)
51.9 ± 3.4
53.7 ± 5.8
1637
° n = 14; °° n = 13.
© 2015 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/).
AcknowledgmentsThis work was supported by the Swiss National Science Foundation (PP00A-114923 to RH; PBZHP3-138801 and PBZH3-147180 to SK), the Emdo Foundation, the Donation UBS AG by order of a client and the Clinical Research Priority Program (CRPP, "Sleep and Health") of the University of Zurich. We thank Maya Ringli (University of Zurich, Zurich, Switzerland), Fiona Pugin (University of Zurich, Zurich, Switzerland), Robert Aellen (University of Zurich, Zurich, Switzerland) and Margot Schaerer (University of Zurich, Zurich, Switzerland) for data collection, and Jonathan Lassonde (University ofConflicts of InterestThe authors declare no conflict of interest.
. Colorado, Usa ) Boulder, Allyson Schumacher, Boulder, USAUniversity of Coloradofor theirColorado, Boulder, USA) and Allyson Schumacher (University of Colorado, Boulder, USA) for their
Jenni and Reto Huber conceived and designed the experiments. Andrina Aepli, Salome Kurth, G Oskar, Andrina Aepli, Salome Kurth, Oskar G. Jenni and Reto Huber conceived and designed the experiments.
and Noemi Tesler performed the experiments. Andrina Aepli, Salome Kurth and Reto Huber analyzed the data and wrote the paper. Andrina Aepli, Salome Kurth, Andrina Aepli, Salome Kurth, and Noemi Tesler performed the experiments. Andrina Aepli, Salome Kurth and Reto Huber analyzed the data and wrote the paper.
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According to this study, caffeine has a significant affect on slow-wave sleep in rats, even a week after intake.
Is the same true for humans? | Purpose of Review ::: This article provides an overview of the evidence of commonly used dietary supplements for insomnia. |
Introduction
Overall, it is estimated that over 50% of the US population will suffer from a sleep disorder at some point in their life [1]. These conditions include disorders of sleep initiation and maintenance (i.e., insomnia), hypersomnolence, and others. As a therapeutic group, there is an abundance of interest in nutraceuticals for these disorders. Many naturally occurring products are manufactured and marketed for a variety of sleep symptoms.
Comprehensive research on these natural products for sleep-related indications is in its adolescence, and there is a spectrum of evidence supporting the efficacy of these agents. The agents range from caffeine, with significant evidence to support its potential in several sleep conditions, to marijuana, with virtually no evidence, and many in between.
Here, we focus on six commonly recognized plant-based nutraceuticals with hypothesized impact on sleep disorders: caffeine, chamomile, cherries, L-tryptophan, marijuana, and valerian. The exclusion of melatonin from this focus is based upon two factors. First, although melatonin may be obtained from a variety of plant sources or from chemical synthesis, formulations have traditionally been derived from animal sources. Second, a number of general and systematic reviews of melatonin are already published in the literature.
The inclusion of any of the agents in this review does not imply endorsement; the agents were selected on the basis of common use in the general population in conjunction with public interest in their research and development. This review will summarize both the historic use and state of the literature for these agents and provide an assessment of the field's understanding of their sleep/wake effects.
Caffeine
Caffeine is among the most widely consumed plant-based drugs worldwide. With the exception of cannabinoid extracts, it is the only agent discussed in this review that has FDA recognized formulations. As such, caffeine is both a nutraceutical and a pharmaceutical product. It is also singular in this discussion of plant-based sleep therapeutics, in that it is used for conditions of excessive sleepiness, rather than the disorders of sleep initiation and maintenance.
There is a wide array of sources for naturally occurring caffeine [2,3]. A typical 8 oz cup of coffee brewed from roasted beans contains roughly 100 mg of caffeine. Teas range from being completely uncaffeinated/decaffeinated to over 100 mg, depending on the type and brewing method. Chocolate and chocolate products contain caffeine, about 10 mg for a 1 oz serving of milk chocolate. Some sources are less well known in the United States. These include guarana, a plant native to South America where it is formulated into food consumables and ingested for its natural stimulating effects [4]. Caffeine (usually obtained from decaffeination processes) can also be added to artificial sources such as soda and energy drinks.
Caffeine (1,3,7-trimethylpurine-2,6-dione) has a number of biochemical actions. Its principal action is adenosine antagonism, and there are a number of caffeine analogs with variable affinities for A1 and A2 receptors [2]. Adenosinergic pathways upregulate non-REM sleep, and it is the antagonistic effect at these receptors that primarily accounts for caffeine's stimulant properties. It also acts as a cyclic AMP phosphodiesterase inhibitor, perhaps contributing to its alertness and mood elevating effects [3]. Caffeine has a number of other proposed bioactive mechanisms, including acetylcholinesterase antagonism that may account for its memory-enhancing properties [5]. In addition to caffeine, coffee and tea contain a number of antioxidants, but it is unclear if these have any particular beneficial action from a sleep or circadian standpoint [6].
On a macrolevel, these actions all contribute to caffeine's stimulant effects. In a rigorous Cochrane meta-analysis, caffeine was found to be effective in controlling errors secondary to shift work and is perhaps as effective as other (potentially more expensive and difficult to obtain prescription) therapies for this purpose [7]. It can also be effective in treating sleepiness in other types of circadian rhythm disorders, such as jet lag [8]. Although several FDA approved stimulants have been studied for residual sleepiness in treated sleep apnea, caffeine has not been studied for this malady. At one time, caffeine was suggested as a therapy for central sleep apnea, but it is no longer routinely used for treatment of this condition.
Caffeine has been demonstrated to improve performance with a number of psychomotor tasks. This quality can be useful both individually and from a public safety standpoint. For instance, caffeine may help to reduce the likelihood of motor vehicle accidents in commercial drivers. In one casecontrol study, Australian researchers polled 530 commercial drivers who had been involved in a recent motor vehicle accident and compared them to 517 control drivers. [9]. After adjustment for confounding factors, drivers who had consumed caffeine (specifically for the purpose of staying awake) had a 63% reduced chance of a crash (odds ratio 0.37, 95% confidence interval 0.27 to 0.50). This study had a number of potential methodological flaws, including recall bias, but suggests that caffeine could reduce the likelihood of a commercial vehicle crash and therefore promote public safety when used in this manner.
The side effects of caffeine are well recognized. Recently, there has been significant interest in establishing the safety of energy drinks, many of which contain significant amounts of caffeine. Agitation, insomnia, and appetite suppression are some of the more common side effects. Palpitations can be common with excessive caffeine ingestion; however, its role in precipitating more serious arrhythmias is speculative [10]. More recently, an association between caffeine intake and hemorrhagic stroke was established in a population based study, although the study examined caffeine ingested in processed form and not from caffeinated beverages [11]. A link between fibrocystic breast diseases has been suggested, but some studies cast doubt on this relationship [12]. In general, most of the side effects of caffeine are minor and selflimited.
Chamomile
Chamomile compound is derived from several plants in the Asteraceae family, native to southern and Eastern Europe. Chamomile has been traditionally served as an infusion, but a number of formulations are available, including tablets, powders, and gelcaps. As with virtually all nutraceuticals, chamomile is considered a dietary supplement and is not FDA regulated. Chamomile has a reputation as a natural aid for insomnia and has been used for millennia in this capacity. In common use, the supplement is generally considered to be soporific, rather than hypnotic, and is easy to find in brick and mortar and online retail outlets throughout the United States.
Chamomile contains several compounds that might have therapeutic effects [13]. In laboratory studies, Apigenin demonstrates anxiolytic properties and appears to be a candidate for chamomile's effectiveness as soporific [14][15][16]. Apigenin is a flavonoid and acts as an antagonist at 1 1 2S GABA A receptors and at 1 GABA C receptors. GABA modulation is a common mechanism for many hypnotics, although these putative receptors are not those modulated by benzodiazepines or benzodiazepine agonists [17]. Apigenin has also been recently studied for additional properties, including anti-inflammatory effects, although the relationship between these and possible sleep inducing effects is still speculative.
The literature is sparse in terms of controlled trials examining chamomile and its sleep inducing properties. In a recent study, 34 subjects were randomized to placebo or 270 mg of chamomile extract [18]. This dosage is much higher than could be prepared and ingested as a tea. Chamomile did not demonstrate a statistically significant benefit over placebo in the predetermined primary sleep endpoints, specifically, sleep diary metrics. Similarly, there was no statistically significant impact on daytime functioning. This is the only high quality clinical trial published to date regarding clinical efficacy of chamomile, and the authors highlight its limitations, including small sample size and challenges in developing effective dosing. All other clinical studies do not meet class 1A evidence and are generally limited to case reports and series. According to Clinicaltrials.gov, there are no other trials that are recruiting or recently completed examining the effect of chamomile on sleep [19].
Like the record on effectiveness, the published literature examining the tolerability of chamomile is generally limited. The only randomized, controlled trial of chamomile did not demonstrate any adverse effects, but the sample size was limited [18]. In other reports, chamomile was linked to contact dermatitis, but only while used topically [20,21]. Although several population based studies have examined the impact of supplements on premature labor and gestational weight, the largest of these did not find any association between chamomile and these outcomes [22]. With limited literature, definitive conclusions about chamomile's side effects are lacking.
Cherries and Cherry Juice
Of many varieties of cherry, tart cherries in particular are purported to have a number of beneficial health effects with some evidence supporting decreases in oxidative stress levels of inflammatory markers and muscle damage following exercise while enhancing muscle recovery [23][24][25][26][27][28].
Montmorency tart cherries (Prunus cerasus) contain several phytonutrients including the phenolic acids with anthocyanins chief among them [29]. Anthocyanin levels in tart cherries exceed those found in sweet cherries and other fruits and a positive linear relationship between anthocyanin levels in cherries and oxidative stress protection in neuronal cells has been reported [30,31]. Tart cherries also contain high levels of anti-inflammatory substances and melatonin [29,31,32]. This suggests two putative sleep-promoting pathways for tart cherries (and perhaps some sweet cherries as well). First, the presence of anti-inflammatory cytokines in tart cherries suggests one potential pathway to sleep enhancement, given that a number of inflammatory cytokines are intricately related to the modulation of sleep [33]. Second, the relatively high content of melatonin in some cherries may serve as a source of exogenous melatonin, a substance with proven sleep-regulating properties. Only very limited clinical research, however, has been conducted to assess the impact of cherries on sleep.
In separate studies, sweet and tart cherries were associated with very modest sleep improvements in already good sleepers. In a crossover study ( = 20) of montmorency tart cherry juice blend, nonsignificant reductions in sleep latency (approximately 5 minutes) and 1 minute in wake after sleep onset (WASO) were measured from sleep diary data [34]. In an uncontrolled study ( = 12), seven varieties of Jerte Valley sweet cherries (Prunus avium) were consumed as whole fruits over seven, separate 72-hour periods. Actigraphy measured improved sleep outcomes compared to baseline [35]. Notably, both studies measured urinary melatonin levels and found increases over basal levels following cherry supplementation (and compared to placebo in the crossover study). Together, these two studies suggest that tart cherry juice and whole sweet cherries each increase melatonin levels in healthy sleepers, making more plausible the possibility that melatonin supplementation may improve sleep in a sleep disordered sample.
Only one study to date has investigated the effect of cherries in a clinical sample. In a small crossover study ( = 15) a montmorency tart cherry juice was associated with statistically significant improvements in self-reported sleep among older adults with insomnia [36]. Compared to placebo, subjects drinking tart cherry juice for two weeks reported less severe insomnia and a reduction in time awake following sleep onset compared to placebo. The magnitude of between-group effects was small to moderate in favor of the tart cherry juice, far less robust than observed from established pharmaceuticals. Nonetheless, the observed effects of tart cherry juice do also compare favorably with the use of exogenous melatonin for insomnia [37].
The amount of melatonin intake from the two tart cherry studies (0.08 mg) is less than the lowest doses of exogenous melatonin (0.3 mg) found to have an impact on sleep [38]. Moreover, the relatively rapid elimination half-life of melatonin (<1 hour) cast some doubt on the improvements seen in wake after sleep onset. It is possible that other mechanisms or pathways to improved sleep underlie the positive signal that remains with respect to cherries and sleep [39]. At this stage, the questions of if and how cherries promote or improve sleep in clinical samples remain unanswered, as does the mechanism of action by which such improvements may occur.
Kava Kava
Kava kava (Piper methysticum) is a plant native to several ecosystems of the Western Pacific, including Hawaii. The sedative and anxiolytic effects of the root from the various substrains of this plant have been known for millennia. Peoples of French Polynesia, for instance, have been using preparations of the plant for a variety of maladies, including symptoms of anxiety and depression. Most raw kava kava is produced and harvested outside of Western nations and imported into European and North American markets for processing. Kavalactones appear to be the primary psychoactive constituents contained in the plant, of which several have been identified. The putative receptors of these compounds include GABA, serotonin, and dopamine, among others [40].
By reputation, kava has a host of therapeutic effects, including anxiolytic, euphoric, and sedative properties. Of these, the anxiolytic benefits of the nutraceutical are probably the best characterized. A 2003 Cochrane report, republished in 2010, analyzed a total of 12 randomized, controlled studies with a total of 700 participants [41]. Several additional studies were excluded from the analysis, as they did not meet inclusion criteria. After rigorous analysis, the authors concluded kava is superior to placebo in controlling anxiety, but the effect size seemed small due to small numbers of subjects included in the trials.
In animal models, one kavalactone, kavain, appeared to change sleep micro-and macroarchitecture compared to other sedatives [42]. An analogous trial has not been conducted in humans. In fact, almost no randomized, controlled trials have explored the efficacy of kava kava in treatment for insomnia and the few published trials have generally included sleep metrics as a secondary outcome measure. A poorly conducted trial published in 2004 examined the impact of a kava extract on sleep scores on a validated sleep questionnaire in subjects with baseline anxiety [43]. After excluding a number of potential subjects, the authors compared 34 subjects taking kava extract to 27 subjects taking placebo. They saw a statistically significant benefit to kava compared to baseline in their predetermined metrics, but both groups saw significant improvements. In the absence of high quality, randomized controlled trials, there is clear opportunity to explore the efficacy of kava in primary insomnia.
Kava has been subject to a number of safety concerns, and this itself is a matter of controversy [44]. The primary one amongst these is the possibility of hepatotoxicity. Due to concerns about this specific side effect as well as other regulatory matters, kava has been highly restricted, particularly in the European Union where it had been banned from import for a number of years. Several authors have suggested that the mode of preparation of the kava extract, including what portion of the plant is used, can play a role in this toxicity. There is suggestion that preparations made from the root of the plant are generally safe, whereas other portions of the plant, such as the stems or leaves, might be more toxic [45]. Likewise, there is some speculation that the method of extraction, specifically the solvents used in the process rather than the plant-based compounds themselves, might be the true offending concern [46].
L-Tryptophan
The effects of the amino acid L-tryptophan on sleep have been investigated since the 1970s with varying support for its role in treating sleep disorders [47]. L-Tryptophan is a precursor to serotonin from its metabolite, 5-HTP. Tryptophan is available in a variety of plant and animal products including eggs, cheese, chocolate, oats, fish, poultry, spirulina, sesame, and sunflower seeds, among many others. Tryptophan is available as an over-the-counter dietary supplement; it is also available in prescription form in Europe, typically as an antidepressant.
Nocturnal administration has been shown to increase concentrations of both serotonin and melatonin; thus its putative mechanism of action may be through either melatonin enhancement or serotonergic effects. Significantly reduced sleep latency and increased subjective ratings of sleepiness in healthy adults during the day have been reported in a number of uncontrolled and controlled studies [48].
Varying doses have been shown to significantly reduce sleep latency and increase subjective ratings of sleepiness in subjects with insomnia [47]. Interestingly, in an experimental tryptophan depletion study in 15 insomnia subjects, tryptophan depletion had a negative impact on sleep continuity, increasing stage 1 sleep and decreasing stage 2 sleep [49]. A systematic review of sixty-four randomized controlled trials exploring the use of alternative modalities to treat insomnia found mixed evidence for L-tryptophan, although this was based on only three studies [50]. In a four-arm RCT ( = 96), Hartmann et al. compared one-week administration of tryptophan, flurazepam, secobarbitol, and placebo [51]. Only flurazepam was associated with subjective sleep improvements relative to placebo. Tryptophan did not improve sleep during the 7-day treatment phase, but in the week following treatment discontinuation, sleep latency did improve relative to placebo. In a blinded crossover trial of high (2 g) versus low/placebo dose (0.04 g) L-tryptophan ( = 39), Demisch et al. reported a significant difference between full L-TRP dose and the placebo dose, but only if the placebo was given first. There was no group difference when the full dose was received first, suggesting a significant placebo effect [52]. Finally, a three-arm RCT ( = 49) compared one-week administration of a food sourced tryptophan (butternut squash seed) to pharmaceutical grade tryptophan and a carbohydrate alone (placebo), all prepared in food bars. In this study, both forms of L-tryptophan resulted in significant improvement on sleep diary measures of insomnia, but similar improvements were noted in the placebo condition such that no significant group × time interactions were observed [53]. The largest improvement was in total sleep time with a 19-minute increase in the squash seed condition and a 42-minute increase in the tryptophan supplement condition, although there was also a 17-minute increase in the placebo condition. In addition, some of the gains were maintained at one-week follow-up. At this time point, placebo was associated with a further increase of additional 24 minutes of total sleep time. Taken together, these trials do not provide convincing support for the efficacy of L-tryptophan for insomnia.
With respect to safety, the sale of tryptophan was banned in the USA from 1991 to 2001 following a large tryptophanrelated outbreak of eosinophilia-myalgia syndrome (EMS) leading to 37 deaths. Sales resumed in 2001, but cautions related to worsening of liver and kidney disease remain due to the link to EMS [54,55]. It is also listed as "likely unsafe" for pregnant or breastfeeding women. On its own, tryptophan is generally safe with mild side effects that include gastrointestinal side effects as well as headache, lightheadedness, drowsiness, dry mouth, visual blurring, muscle weakness, and sexual problems. In addition, there may be major interaction with serotonergic agents such as many antidepressants, leading to serious side effects such as serotonin syndrome. It might act synergistically with sedative-hypnotic medications to cause oversedation; caution should be used when considering with central nervous system depressants as to avoid excessive sleepiness and sedation.
In sum, there is evidence supporting a sleep moderating effect of L-tryptophan. Some safety concerns remain from the EMS outbreak and from the possible severe interaction effects (especially with serotonergic agents), but L-tryptophan is generally well-tolerated with limited side effects. Controlled trials in samples of insomnia patients, however, are quite limited and their combined findings are mixed at best.
Marijuana
In recent years, there has been significant interest in medical marijuana as a treatment for a variety of medical conditions, especially for, but not exclusive to, palliation. Cannabinoids are thought to exert their effects primarily through a variety of G-couples cannabinoid receptors in the central nervous system and in peripheral tissues. The marijuana plant can contain over 60 cannabinoids, some of which appear to be more bioactive than others [56].
Leaving aside the recreational history of marijuana, the plant has generated significant interest over millennia for its purported medicinal properties. In the United States, the cultivation of the plant was referenced as early as the 17th century. In general, there was a permissive attitude towards the drug, both recreationally and medicinally, until the early 20th century. Marijuana was included in efforts to control more socially dangerous drugs, such as opiates and cocaine throughout the 1900s. It came under increasing regulation, either by taxation or direct restriction, until the 1950s, when both the Boggs Act and the Marijuana Control Act mandated sentences for drug offenders.
Both before and during this time, marijuana has been described for relief of a variety of conditions, including pain, spasticity, emesis, and anorexia. The medicinal use of marijuana has included synthetic cannabinoids in tablet form, as well as the delivery of more "natural" forms of the drug such as smoking or alimentary ingestion. The FDA released a policy statement in 2006 that there was no sound medical evidence supporting the use of marijuana for medical purposes; since that time, 10 states have approved medical marijuana bills into law, and the controversy shows no signs of abating [57].
With this background, there is interest in considering this plant-based drug for the management of sleep disorders. It bears noting that there are significant legal and quality control hurdles in conducting medical research on cannabis [58]. With these limitations, it is important to highlight that the absence of evidence does not necessarily imply evidence of absence.
The literature is sparse with observational studies regarding the effects of cannabinoids on sleep. Many of these reports were published over 40 years ago and are limited by small sample size. Regarding sleep architecture, the evidence about cannabinoid's impact is conflicting. The reports varied in regard to dosage and chronicity of THC administration, leading to a great deal of methodological inconsistency. In general, the case series are consistent in that acute THC administration reduced REM sleep in study subjects [59,60], although at least one report was not supportive of this finding [61]. There was no agreement as to THC's impact on slow wave sleep, with some studies suggesting increase in this stage and others suggesting decrement or no change [60,62,63]. There was no described trend for metrics of insomnia, such as number of awakenings or sleep onset latency (SOL). A few of the papers did describe increased sleep onset latency or wake after sleep onset in the withdrawal state [60,62,64]. These observations provide little insight into the mechanisms of sleep regulation of THC. It also bears noting that change in sleep architecture, particularly in regard to total percentages of sleep stages, does not necessarily confer therapeutic advantage. For instance, most commonly prescribed antidepressant medications suppress REM sleep, but this has no known direct detrimental or salutatory sleep effect on the individual patient. Similarly, changes in sleep architecture mediated by THC do not necessarily imply a therapeutic effect.
There is no published evidence that demonstrates benefit of marijuana in the management of primary sleep disorders. Specifically, PubMed searches for cannabis and sleep, cannabis and insomnia, and cannabis and sleepiness did not produce any studies that have explored the impact of cannabinoids on disordered sleep. Likewise, there are no published data that demonstrate an impact of cannabis in treatment for posttraumatic stress disorder, a complex condition with sleep disturbances as an essential feature.
Cannabis has been demonstrated in several clinical trials to improve chronic pain in a variety of patient populations [65]. Many of these trials did not include a sleep outcome and any benefit to cannabis on sleep, even in patients with chronic pain, is still speculative.
The list of potential side effects of marijuana is long, politically charged, and beyond the scope of this review. Like any drug, marijuana, with multiple bioactive agents, could certainly be harmful depending on a number of factors. There is evidence for psychological dependency. The inhalation of marijuana smoke has also been implicated in periodontal and pulmonary diseases [66,67]. These potential drawbacks do need to be considered for a general patient population.
At this time, there is insufficient evidence to prove definitively the impact of THC on sleep architecture or to support the use of marijuana in the management of sleep disorders, but the topic has been subject to almost no scientific scrutiny. Future research should consider these questions, as well as indications for the drug, potential side effects, and the still significant legal hurdles in many states.
Valerian
Valerian is a perennial herb that has long been held to have sedative properties. The Greek physician Galen recommended valerian for insomnia. The most common species from which valerian is derived is Valeriana officinalis. Valerian is extracted from the dried root and rhizomes of this plant by soaking in one of several solutions (water, ethanol and water, or methanol and water) and then either centrifuging or drying the mixture to concentrate the primary active plant compounds including valerenic acids and amino acids [68].
An efficacious dose is considered to be one which has the equivalent of 2 to 3 grams of dried root material. Although commercially available preparations of valerian are most common in tablets ranging in dose from 300 to 600 mg/day and to a lesser extent in 2-4 mL tinctures [69], it is impossible to determine their valerian equivalent when extraction ratios are not provided. One pharmacokinetic study in healthy subjects taking a 600 mg dose of valerian extract, with an undisclosed extraction ratio, observed peak concentrations at 30-120 minutes with a mean elimination half-life of 1.1 hours and its marker, valerenic acid, was observed in serum for up to 5 hours [70].
The precise mechanism of action for valerian is unknown, as is what compound or combination of compounds is responsible for any sedating effect. The main putative pathway is thought to occur through inhibition of sympathetic activity by action upon the neurotransmitter gammaaminobutyric acid (GABA), although it may also be via binding with adenosine (A1) and/or serotonin (5-HT-5a) receptors [71,72]. Importantly, like with kava kava, the solution used in the extraction method (the water to alcohol ratio) can dramatically impact the concentration of constituent compounds extracted [73]. Moreover, since valerian is not FDA regulated, the content and concentrations can vary from the listed amount on labels in the United States [74]. Under the auspices of the European Pharmacopoeia, preparation/dosage control in Europe is stricter. In addition, valerian can be prepared in combination with other herbs such as hops (Humulus lupulus) or lemon-balm (Melissa officinalis), further complicating the assessment of valerian's effect on sleep.
With respect to safety, valerian is on the FDA's GRAS (generally recognized as safe) list and is approved for use as a food. The main secondary effects of valerian include gastrointestinal effects such as diarrhea, abdominal pain, nausea, and pyrosis and central nervous system effects such as headache, nervousness, and drowsiness, although these effects are generally mild and self-limited. With the exception of diarrhea, none have been elevated when compared to placebo in clinical trials [75,76]. There are no notable interactions between valerian and pharmaceuticals, but caution might suggest avoiding it in combination with benzodiazepines.
The empirical evidence for valerian on sleep remains inconclusive due to contradictory findings. Several studies have found no effect of a single dose of valerian [77][78][79]. A systematic review of 29 controlled and eight open label trials concluded that, despite some positive studies, the majority of findings were negative and, therefore, that there is no overall effect of valerian, regardless of preparation type or whether or not it was combined with other nutraceuticals [75]. A subsequent review of sixteen studies exploring the treatment of insomnia using valerian with or without hops concluded that twelve studies showed some sleep benefit of valerian [80]. This review included 3 uncontrolled trials. Furthermore, there were significant methodological differences among the thirteen RCTs. Among the RCTs, positive effects of valerian were observed in 1 of 10 assessing total sleep time; 5 of 11 assessing sleep latency; 3 of 6 assessing slow wave sleep; 2 of 10 assessing nocturnal awakenings; and 4 of 13 assessing sleep quality.
A meta-analysis found a statistically greater effect of valerian on sleep quality compared to placebo, but it found that there were no other differences [81]. A subsequent metaanalysis of 18 RCTs, which included three newer randomized trials, found a difference in effect favoring valerian when a sleep quality variable was dichotomized but no difference in sleep quality measured by visual analog scale and no difference in sleep latency [76]. The authors further conclude the most recent clinical trials were of high methodological quality and sufficient sample size, but their combined results were not conclusive.
In the largest trial included in the meta-analysis, Oxman and colleagues (2007) conducted a multicentre trial comparing the equivalent of approximately 3.6 grams of valerian from commercially available valerian tablets to placebo taken for two weeks in 405 adult participants with >1month insomnia and a score > 5 on the Pittsburgh Sleep Quality Index (PSQI) [82]. There were very few significant differences between groups on the primary and secondary sleep outcomes; the authors conclude that valerian may have a small effect on sleep quality but is unlikely to reduce the time it takes to fall asleep or increase daytime energy level.
Two high quality studies have been published since this large meta-analysis exploring valerian's impact on sleep.
In one, 100 postmenopausal women aged 50-60 who had insomnia were randomly assigned to receive twice a day for four weeks 530 mg of a valerian root extract or 50 mg starch as placebo in capsules (although the extraction ratio was not provided, so the valerian dose equivalent is unknown). Nonetheless, in this study, valerian was associated with a greater reduction in PSQI scores over the treatment period (from 9.8 to 6.0) than placebo (from 11.1 to 9.4) and a greater proportion of participants achieving a 5-point reduction in their PSQI score (30% versus 4%) [83]. In another, 91 patients diagnosed with primary insomnia, perceived total sleep time of <6 hours, and an Insomnia Severity Index score > 7 were randomized to receive a 10 mg zolpidem tablet or one tablet containing 300 mg of a valerian extract (standardized to 0.8% valerenic acid), hops, and passion flower (Passiflora incarnata) extracts at bedtime for two weeks [84]. Thirtynine subjects in each group completed the study, which found significant improvements on sleep diary-measured sleep latency, total sleep time, and nocturnal awakenings as well as significant improvements on the ISI in each group. There were no time by group differences on any of these measures, suggesting equivalency between zolpidem and this particular formulation of valerian, hops, and passion flower.
In sum, the evidence to support the use of valerian as a sleep aid for patients with insomnia remains rather mixed, with more negative than positive studies overall. A few high quality studies now report modest benefits of valerian for insomnia patients. The safety of valerian is now wellestablished.
Summary
From even this basic review of a few of the nutraceutical supplements available for sleep disorders, it is clear that there is a spectrum of evidence to support their use. With few exceptions, a general theme with these agents is that there are historical and anecdotal reports of sleep benefit, but the science falls significantly short of class IA evidence. In fact, some of the agents have essentially no published data at all to support their use, even as case reports. The National Institutes of Health has National Center for Complementary and Integrative Health (NCCIH), with a 2015 budget of 124.1 million dollars, about two one-hundredths that of the National Cancer Institute [85]. For those who have an interest in these plant-based products for use in sleep disorders, the hope is that some of this modest budget along with other support will be granted for these types of research.
Conflict of InterestsThe authors declare that there is no conflict of interests regarding the publication of this paper.
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| Why is sleep important to maintaining a healthy body? | Which supplements shouldn't be taken at night if you want to have a good night's sleep?
I will start with Caffeine, Guarana, ECGC, Ginseng, Rhodiola Rosea, ALCAR, CoQ10, and B-Vitamins. Anything else? | I know stimulants make sleep difficult, but this doesn't make sense. It's like, I can fall asleep fine, and my sleep quality is fine for those 4 hours, BUT, without fail I will wake up at almost 4 hours on the dot and not be able to fall back to sleep. Can anyone explain why this happens?
This happens even with the help of sleep aids. | 1,999,790 | Abstract Caffeinated energy drinks are immensely popular and increasingly consumed by youth and adults internationally to counteract effects of insufficient sleep, and improve performance. However, the research over last decade has observed an increased prevalence of sleep-related complaints in caffeine-users. With increased awareness of the role of sleep disturbances in health and disease in general public, the review of this bidirectional nature of caffeinated products and sleep disturbances is critical. This chapter will review the epidemiology of caffeine, energy drinks, and prescribed stimulants. We will then discuss the mechanism of caffeine on sleep-wake homeostasis and address the genetic and environmental factors related to the individual variation of caffeine effects on sleep. The health consequences due to caffeine-sleep paradigm will be briefly discussed. Finally, we will include few recommendations keeping in mind the limitations in the current literature. | Caffeine is the most commonly ingested psychoactive drug worldwide with increasing consumption rates among young individuals. While caffeine leads to decreased sleep quality in adults, studies investigating how caffeine consumption affects children's and adolescents' sleep remain scarce. We explored the effects of regular caffeine consumption on sleep behavior and the sleep electroencephalogram (EEG) in children and adolescents (10-16 years). While later habitual bedtimes (Caffeine 23:14 ± 11.4, Controls 22:17 ± 15.4) and less time in bed were found in caffeine consumers compared to the control group (Caffeine 08:10 ± 13.3, Controls 09:03 ± 16.1), morning tiredness was unaffected. Furthermore, caffeine consumers exhibited reduced sleep EEG slow-wave activity (SWA, 1-4.5 Hz) at the beginning of the night compared to controls (20% ± 9% average reduction across all electrodes and subjects). Comparable reductions were found for alpha activity (8.25-9.75 Hz). These effects, however, disappeared in the morning hours. Our findings OPEN ACCESS Brain Sci. 2015, 5 442 suggest that caffeine consumption in adolescents may lead to later bedtimes and reduced SWA, a well-established marker of sleep depth. Because deep sleep is involved in recovery processes during sleep, further research is needed to understand whether a caffeine-induced loss of sleep depth interacts with neuronal network refinement processes that occur during the sensitive period of adolescent development. | BACKGROUND ::: Sleepiness is one of the most burdensome symptoms of sleep-disordered breathing (SDB). While caffeine is frequently used to avert sleepiness, the association between SDB and caffeine use has not been thoroughly explored. The current study examined whether SDB is associated with caffeine consumption and if factors such as sex, age, and daytime sleepiness explain or modify the association. ::: ::: ::: METHODS ::: Data from the Sleep Heart Health Study, a community-based study on the consequences of SDB, were used to characterize the association between SDB and caffeine intake. SDB was assessed with full-montage polysomnography. Caffeine use was quantified as the number of cans of soda or the cups of coffee or tea consumed daily. The Epworth Sleepiness Scale was used to assess daytime sleepiness. Multivariable negative binomial regression models were used to characterize the independent association between SDB and caffeine use. ::: ::: ::: RESULTS ::: Caffeinated soda, but not tea or coffee, intake was independently associated with SDB severity. Compared with participants without SDB, the relative ratios for caffeinated soda consumption in women with mild, moderate, and severe SDB were 1.20 (CI, 1.03-1.41), 1.46 (CI, 1.14-1.87), and 1.73 (CI, 1.23-2.42), respectively. For men, an association was only noted with severe SDB and caffeinated soda use. Age did not modify the SDB-caffeine association, and sleepiness could not explain the observed associations. ::: ::: ::: CONCLUSIONS ::: SDB is independently associated with caffeinated soda use in the general community. Identifying excessive caffeine used in SDB has potential significance given the cardiovascular effects of caffeine and untreated SDB. | Background/Aim The aim of this study was to examine the extent to which additive genetic, shared environmental and non‐shared environmental factors contribute to adolescent and preadolescent sleep problems. Methods The sample consisted of a cohort of 270 monozygotic and 246 dizygotic twins from a university‐based twin registry. Results Results demonstrated that genetic and environmental influences each appear to be important to adolescent sleep problems. Conclusions While the magnitude of genetic influence on sleep problems was consistent with findings from the adult literature, it was smaller than in studies with younger children, suggesting genetic effects may be less influential in adolescence and adulthood. | Acute caffeine intake can delay sleep initiation and reduce sleep intensity, particularly when consumed in the evening. However, it is not clear whether these sleep disturbances disappear when caffeine is continuously consumed during daytime, which is common for most coffee drinkers. To address this question, we investigated the sleep of twenty male young habitual caffeine consumers during a double-blind, randomized, crossover study including three 10-day conditions: caffeine (3 × 150 mg caffeine daily), withdrawal (3 × 150 mg caffeine for 8 days, then switch to placebo), and placebo (3 × placebo daily). After 9 days of continuous treatment, electroencephalographically (EEG)-derived sleep structure and intensity were recorded during a scheduled 8-h nighttime sleep episode starting 8 (caffeine condition) and 15 h (withdrawal condition) after the last caffeine intake. Upon scheduled wake-up time, subjective sleep quality and caffeine withdrawal symptoms were assessed. Unexpectedly, neither polysomnography-derived total sleep time, sleep latency, sleep architecture nor subjective sleep quality differed among placebo, caffeine, and withdrawal conditions. Nevertheless, EEG power density in the sigma frequencies (12-16 Hz) during non-rapid eye movement sleep was reduced in both caffeine and withdrawal conditions when compared to placebo. These results indicate that daily caffeine intake in the morning and afternoon hours does not strongly impair nighttime sleep structure nor subjective sleep quality in healthy good sleepers who regularly consume caffeine. The reduced EEG power density in the sigma range might represent early signs of overnight withdrawal from the continuous presence of the stimulant during the day.Caffeine is the most popular psychoactive substance in the world 1 , consumed daily by around 80% of the population 2 . While caffeine is frequently used to counteract sleepiness and boost performance 3 , its consumption is commonly avoided in the evening 4,5 to prevent adverse consequences on nocturnal sleep 3 . The sleep disrupting effects of caffeine are mainly attributed to its influence on the homeostatic component of sleep-wake regulation. Sleep homeostasis describes the increase in sleep pressure during time awake and its dissipation during the following sleep episode 6 , which has been suggested to be related to rising and decreasing concentrations of adenosine 7 . Caffeine is an adenosine receptor antagonist, which blocks the A 1 and A 2A adenosine receptors in the central nervous system 1 . It may, thus, attenuate the increase in sleep pressure during wakefulness 8 and lead to delayed sleep initiation and more superficial sleep 9 .The effects of caffeine intake on the quality and quantity of sleep depend on the timing of its consumption. More specifically, caffeine consumed in the evening hours prolongs sleep latency 10-14 , reduces total sleep time (TST) 10-12,14,15 , shortens deep sleep 10,12-15 , and decreases electroencephalographically (EEG)-derived slow-wave activity (SWA) 10 , while activity in the sigma range is increased 10 . However, evening caffeine intake only accounts for approximately 10-20% of the total daily caffeine intake in regular consumers 4,5 . It needs to be elucidated whether habitual caffeine intake restricted to the morning and afternoon hours similarly affects nighttime sleep. dom factor 'subject' . The LSMEANS statement was used to calculate contrasts and degrees of freedom were based on the approximation by Kenward and Roger 50 . Post-hoc comparisons were adjusted for multiple comparisons by applying the Tukey-Kramer method. A statistical significance was defined as p < 0.05. One dataset has been excluded from all the analyses due to non-compliance with the treatment requirements (caffeine: n = 1). | Background and goal Sleep problems and challenging behavioural symptoms are frequently reported among nursing home residents with dementia. Coffee with caffeine is consumed frequently by these residents and can have a negative effect on sleep and behaviour in older persons with dementia. In this interventional study, the effect of caffeine reduction on sleep and challenging behavioural symptoms in nursing home residents with dementia was investigated. Methods In 21 nursing home residents with dementia living in 1 dementia special care unit, caffeine was gradually eliminated in the afternoon and evening. During pre-intervention and post-intervention period the care workers daily scored sleep by a specially developed sleep questionnaire. Behavioural symptoms were scored in the afternoon and evening using four items of the NPI-NH: agitation/aggression, apathy, irritability and aberrant motor behaviour. Results A significant improvement in sleep scores (Wilcoxon signed-rank test, p = 0.015) and apathy (Wilcoxon signed-rank test, p = 0.020) was found after eliminating caffeine intake in the afternoon and evening. No significant changes occurred in agitation/aggression, irritability and aberrant motor behaviour. Discussion This pre-post pilot study found a significant positive effect of caffeine reduction on sleep and apathy and warrants further investigation in a larger controlled study. | where was the study done about caffeine induced sleep disorder | OBJECTIVE: To review the literature regarding the genetics of sleep disorders in childhood and adolescence. SOURCES: Articles published in the past 5 years were searched on MEDLINE using the keywords sleep and genetics. Abstracts were then analyzed. Classical articles with the first description of genes were also included. SUMMARY OF THE FINDINGS: We often find familial recurrence in many sleep disorders. However, gene loci were discovered for only a few of them. We describe sleep disorders transmitted by genetic heritance and also those in that, although a gene was not found, familial recurrence is high. CONCLUSION: Although most of the sleep disorders do not have by now an identified molecular basis, modern techniques are being increasingly applied to determine the contribution of genes to sleep and its associated disorders. The clinical importance of these discoveries may relate not only to improving diagnostic methods but also as a target for drug development. Language: pt | on the substantiation of a health claim related to caffeine and increased alertness pursuant to Article 13 ( 5 ) of Regulation ( EC ) No 1924 / 2006 |
1,999,791 | are there ticks in oklahoma? | Watching for Ticks. The brown dog tick has become established in Alaska in the Fairbanks and North Pole area, and also in Anchorage/Eagle River, Chugiak and Valdez. The Brown Dog tick prefers indoors, especially kennel environments and homes. | What are facts on Oklahoma? | About 20 species of hard ticks are found in Oregon, but only four are known to prey on humans: western black-legged tick, Rocky Mountain wood tick, American dog tick and Pacific Coast tick. The western black-legged tick is the only known carrier of Lyme disease in Oregon. | What is oklahoma's state game animal and state park? | What is the animal life in thee state of oklahoma? | What is an interesting fact about oklahoma? | Where is oklahoma located on or near? | What mountains are in the arkansas and oklahoma? | 1,999,791 | Lone star ticks are not the only ticks in Oklahoma, but they are the ones most commonly associated with ehrlichiosis — as well as tularemia, southern tick-associated rash illness, the rare Heartland virus and the alpha-gal — or meat — allergy. Dog ticks are the second most active now. | where was the lone star tick found in missouri | are there ticks in missouri? | are there ticks in fairbanks alaska? | Early Questing by Lone Star Tick Larvae, New York and Massachusetts, USA, 2018 | are there ticks in mississippi? | the okapi is endemic to which country | ixodes holocyclus is the more common name for which tick | where is the bourbon virus found in oklahoma |
1,999,792 | in which city did russian author mark aldanov die | Russian literature Vladislav Khodasevich, Georgy Ivanov and Vyacheslav Ivanov; novelists such as Mark Aldanov, Gaito Gazdanov and Vladimir Nabokov; and short story Nobel Prize-winning writer Ivan Bunin, continued to write in exile. Some writers dared to oppose Soviet ideology, like Nobel Prize-winning novelist Aleksandr Solzhenitsyn, who wrote about life in the gulag camps. The Khrushchev Thaw brought some fresh wind to literature and poetry became a mass cultural phenomenon. This "thaw" did not last long; in the 1970s, some of the most prominent authors were banned from publishing and prosecuted for their anti-Soviet sentiments. The end of the 20th century was a | the central character's mindset. The House with the Mezzanine "The House with the Mezzanine" () is an 1896 short story by Anton Chekhov, subtitled (and also translated as) "An Artist's Story" (Рассказ художника, "Rasskaz khudozhnika"). The story was first published in the April 1896 issue of "Russkaya Mysl", with the subtitle 'An Artist's Story' (Рассказ художника). With minor changes it was included by Chekhov into Volume 9 of his Collected Works published by Adolf Marks in 1899–1901. During Chekhov's lifetime the story was translated into Bulgarian, Hungarian, German, Serbo-Croatian and Czech languages. The first mention of the story dates back | the central character's mindset. The House with the Mezzanine "The House with the Mezzanine" () is an 1896 short story by Anton Chekhov, subtitled (and also translated as) "An Artist's Story" (Рассказ художника, "Rasskaz khudozhnika"). The story was first published in the April 1896 issue of "Russkaya Mysl", with the subtitle 'An Artist's Story' (Рассказ художника). With minor changes it was included by Chekhov into Volume 9 of his Collected Works published by Adolf Marks in 1899–1901. During Chekhov's lifetime the story was translated into Bulgarian, Hungarian, German, Serbo-Croatian and Czech languages. The first mention of the story dates back | and Marshal Vasilevsky considered him very talented. page from warheroes.ru in Russian Markian Popov Markian Mikhaylovich Popov (; 19021969) was a Soviet military commander, Army General (26 August 1943), and Hero of the Soviet Union (1965). During the German–Soviet War at various times he commanded a number of Armies and a number of Fronts. His career was uneven. In June 1941 he was Commander of the Leningrad Military District, then Northern Front (24 June – 5 September). The Germans advanced with a terrific speed, but then they were halted just before Leningrad. The army group was on 26 August renamed | and Marshal Vasilevsky considered him very talented. page from warheroes.ru in Russian Markian Popov Markian Mikhaylovich Popov (; 19021969) was a Soviet military commander, Army General (26 August 1943), and Hero of the Soviet Union (1965). During the German–Soviet War at various times he commanded a number of Armies and a number of Fronts. His career was uneven. In June 1941 he was Commander of the Leningrad Military District, then Northern Front (24 June – 5 September). The Germans advanced with a terrific speed, but then they were halted just before Leningrad. The army group was on 26 August renamed | Tsar (film) his paw. Metropolitan Philip, horrified by the senseless brutality of the Tsar, seeing the futility of their attempts to persuade the Tsar to give up violence, enters the arena, and raises the icon. During a service at the Church, he refuses to bless the Tsar, who furiously strips the Metropolitan of his rank and forces him to watch the execution of his nephew on the rack. The Tsar decides to pardon Philip himself, but forever exiles him to a monastery, where he is treated as an ordinary prisoner, shackled, deprived of even water. 4. The Tsar's fun. Heinrich von Staden | Vladimir Gagloyev () (February 1, 1927 in Dodot, Tskhinvali District, South Ossetia – February 12, 1996 in Moscow, Russia) was an Ossetian writer.
1927 births
1996 deaths
Ossetian writers
People from Tskhinval district | Andrei Amalrik, whom I knew well in the 1970's, was a remarkable Soviet dissident in that he not so much hated the regime as scoffed at it. His memoir details the absurdities that were Soviet Communism. It is hard to put down. | 1,999,792 | immediately gained him popularity. Then followed a trilogy of novels attempting to trace the roots of the Russian Revolution. He also wrote a tetralogy of novels about Napoleonic wars. All in all, he published 16 larger literary works and a great number of articles and essays. Ivan Bunin, the first Russian writer to win the Nobel Prize for Literature, nominated Aldanov for Nobel Prize a total of six times - in 1938, 1939, 1947, 1948, 1949, and 1950. Mark Aldanov died in Nice, France. His extensive correspondence with Vladimir Nabokov, Ivan Bunin, Alexander Kerensky and other emigre celebrities was published | which country was the first to reject the nobel prize for literature in 1901 | when was buzz aldrin the book published | when did russian cosmonaut nikolai budarin become a candidate to | russian physician nikolai dahl died in which year | He was a full member of the Russian Academy of Sciences and a laureate of the USSR State Prize ( 1976 ) . | thomas mann won the nobel prize for literature in 1901 for which novel | which polish novelist won the nobel prize for literature in 1905 with eliza orzes | History of the Book in Creative Heritage of Mykhailo Hrushevskyi |
1,999,793 | Crustal conductivity anomalies in central Sweden and southwestern Finland | Geology of Sweden The geology of Sweden is the regional study of rocks, minerals, tectonics, natural resources and groundwater in the country. The oldest rocks in Sweden date to more than 2.5 billion years ago in the Precambrian. Complex orogeny mountain building events and other tectonic occurrences built up extensive metamorphic crystalline basement rock that often contains valuable metal deposits throughout much of the country. Metamorphism continued into the Paleozoic after the Snowball Earth glaciation as the continent Baltica collided with an island arc and then the continent Laurentia. Sedimentary rocks are most common in southern Sweden with thick sequences | Resistivity structure of the upper crust in Iceland | The temporal variation of Mesoarchaean volcanism in the Suomussalmi greenstone belt, Karelia Province, Eastern Finland | I review recent investigations on the electrical conductivity of the lithosphere and asthenosphere in Europe. The principal method in the reviewed studies is the magnetotelluric method, but in many cases other electromagnetic methods (e.g., magnetovariational profilings and geomagnetic depth soundings) have provided additional information on subsurface conductivity or have been the primary method. The review shows that the magnetotelluric method has been used, and is being used, in all kinds of environments and for many different processes shaping the crust and lithosphere. The crust is very heterogeneous, both with respect to the scale of conductive/resistive features and interpretations: research targets vary from Archaean palaeostructures to ongoing processes. The European database of the depth to the lithosphere-asthenosphere boundary (LAB) in Europe is updated, and a new map showing lateral variations of the depth of LAB is provided. The compilation shows that (1) the Phanerozoic European lithosphere, with considerable variations (45–150 km), is much thinner than the Precambrian European lithosphere, (2) the Trans-European Suture Zone is a major electrical border in Europe separating electrically (as well as geophysically and geologically in general) two quite different settings, (3) the thinnest lithosphere is found under the extensional Pannonian Basin (45–90 km), (4) in most of the East European Craton there are no indications of a high conductivity zone in upper mantle. In many regions there is no information at all on upper mantle conductivity, which calls for pan-European projects to operate arrays of simultaneously recording instruments with long recording periods (2–8 months) and dense spatial sampling (20–50 km). | I review recent investigations on the electrical conductivity of the lithosphere and asthenosphere in Europe. The principal method in the reviewed studies is the magnetotelluric method, but in many cases other electromagnetic methods (e.g., magnetovariational profilings and geomagnetic depth soundings) have provided additional information on subsurface conductivity or have been the primary method. The review shows that the magnetotelluric method has been used, and is being used, in all kinds of environments and for many different processes shaping the crust and lithosphere. The crust is very heterogeneous, both with respect to the scale of conductive/resistive features and interpretations: research targets vary from Archaean palaeostructures to ongoing processes. The European database of the depth to the lithosphere-asthenosphere boundary (LAB) in Europe is updated, and a new map showing lateral variations of the depth of LAB is provided. The compilation shows that (1) the Phanerozoic European lithosphere, with considerable variations (45–150 km), is much thinner than the Precambrian European lithosphere, (2) the Trans-European Suture Zone is a major electrical border in Europe separating electrically (as well as geophysically and geologically in general) two quite different settings, (3) the thinnest lithosphere is found under the extensional Pannonian Basin (45–90 km), (4) in most of the East European Craton there are no indications of a high conductivity zone in upper mantle. In many regions there is no information at all on upper mantle conductivity, which calls for pan-European projects to operate arrays of simultaneously recording instruments with long recording periods (2–8 months) and dense spatial sampling (20–50 km). | East European Craton The East European Craton (EEC) is the core of the Baltica proto-plate and consists of three crustal regions/segments: Fennoscandia to the northwest, Volgo-Uralia to the east, and Sarmatia to the south. Fennoscandia includes the Baltic Shield (also referred to as the Fennoscandian Shield) and has a diversified accretionary Archaean and early Proterozoic crust, while Sarmatia has an older Archaean crust. The Volgo-Uralia region has a thick sedimentary cover, however deep drillings have revealed mostly Archaean crust. There are two shields in the East European Craton: the Baltic/Fennoscandian shield and the Ukrainian shield. The Ukrainian Shield and the | Dialects in Norway vary from region to region and, because of the existence of Nynorsk and Bokmål, they can vary greatly; the north end of the continuum has very little in common with the southern end. Can we therefore say they are living in a diglossic situation despite them being part of the same language? | We summarized the seismomagnetic research resnlt in the 2014 American Geophysical Union( AGU) Fall M eeting which was held in San Francisco,USA on Dec. 15 ~ 19,2014. The papers of the AGU meeting fully showed the new progresses and the new results of seismomagnetic research,and the development prospect of it in the future. The seismomagnetic research is very important for the earthquake prediction. The research results display that the lithospheric magnetic anomalies variation in local region has the seismomagnetic precursor information,and it is an important basis for predicting the local seismic activity. | 1,999,793 | Summary ::: ::: Lateral conductivity variations in the Earth's crust in central Sweden and southwestern Finland were mapped using magnetic field variations recorded simultaneously by 29 Gough–Reitzel-type magnetometers in summer 1985. Three events of 3 or 4 h were digitized and analysed to obtain single-station induction arrows and interstation horizontal field transfer functions. The 1985 magnetometer array covered part of the BEAR (Baltic Electromagnetic Array Research) array operated in 1998 on the Fennoscandian Shield. Results from eight BEAR sites are used to control and to supplement the 1985 array results. The conductivity of the crust was found to increase in the western part of the array in western central Sweden. Crustal conductors were found both in the western part of the array and in the Baltic Sea area in the eastern part of the array. 3-D modelling based on the induction arrows revealed a major conductivity anomaly in the middle and lower crust under the archipelago of Southwest Finland. | Geomagnetically induced currents (GIC) are directly described by ground electric fields, but estimating them is timeconsuming and requires knowledge of the ionospheric currents as well as the three-dimensional distribution of the electrical conductivity of the Earth. The time derivative of the horizontal component of the ground magnetic field (dH/dt) is closely related to the electric field via Faraday's law, and provides a convenient proxy for the GIC risk. However, forecasting dH/dt still remains a challenge. We use 25 years of 10 s data from the North European International Monitor for Auroral Geomagnetic 5 Effects (IMAGE) magnetometer network to show that part of this problem stems from the fact that instead of the primary ionospheric currents, the measured dH/dt is dominated by the signature from the secondary induced telluric currents nearly at all IMAGE stations. The largest effects due to telluric currents occur at coastal sites close to highly-conducting ocean water and close to near-surface conductivity anomalies. The secondary magnetic field contribution to the total field is a few tens of percent, in accordance with earlier studies. Our results have been derived using IMAGE data and are thus only valid for the 10 involved stations. However, it is likely that the main principle also applies to other areas. Consequently, it is recommended that the field separation into internal (telluric) and external (ionospheric and magnetospheric) parts is performed whenever feasible, i.e., a dense observation network is available. | Synchronous annual variations in the geoelectric and geomagnetic field are studied on the basis of long-term electromagnetic monitoring. It is shown that the annual geoelectric variations have intraterrestrial origin and are not related to the annual geomagnetic variations. Temporal variations in the magnetotelluric impedance and magnetic tipper, which characterize the electrical conductivity of the geological environment, are analyzed. It is established that annual variations in the magnetotelluric impedance mainly describe the variations in the electrical conductivity of surface crustal layers and are less sensitive to the deep electrical conductivity of the Earth. The annual variations in the imaginary magnetic tipper at the periods of 1000–3000 s probably reflect the changes in conductivity of a deep transversal low-resistive zone (the fault). It is suggested that annual variations in the geoelectrical and geomagnetic fields, as well as in the electrical conductivity of the geological environment, arise as a response to the changes in the geodynamical processes caused by the revolution of the Earth around the Sun. | Geomagnetically induced currents (GIC) in power systems can interfere with the system operation and, in extreme cases, can damage transformers and cause power blackouts. A notable example is the magnetic disturbance of March 13, 1989 that caused a blackout of the Hydro-Quebec system. The size of the GIC depends on the inducing magnetic-field variations, earth conductivity structure, and system characteristics. This paper examines the earth models developed for Quebec and shows how the changes in earth models have changed the electric-field values calculated for the March 13, 1989 storm. These calculations are made using data from two magnetic observatories: one at the southern end of Quebec and one at the northern end. It is shown how the choice of magnetic-field data and uncertainty in the earth model influence the calculated electric-field values. | Satellite magnetic data: The exploration industry rates their usefulness | Variations in horizontal and vertical components of the telluric field are studied within the range of periods from a few tens of seconds to diurnal and longer variations. Variations caused by an external ionospheric source are used for studying the geoelectric heterogeneity of the medium. For this purpose, an electric tipper is introduced by analogy with the geomagnetic field and its frequency response is examined. The magnetotelluric impedance is studied using data of remote geomagnetic observatories. According to the data of monitoring of the electric tipper and magnetotelluric impedance, anomalous effects are revealed that can be related to earthquakes with K ≥ 12. A method is developed for the extraction of electric field anomalies produced by intraterrestrial electric sources. | The magnetic dipole positioning method which uses single-point measurement of the magnetic field vector and the magnetic tensor data are strongly interfered by the geomagnetic field,which greatly limits its usefulness.An magnetic dipole single-point tensor positioning based on the difference method was proposed.This method used differential mode,and could eliminate the geomagnetic field and other common-mode interference.Simulation results showed that,in the presence of geomagnetic method,the original method was basically impossible to achieve the position,but this method had a higher positioning accuracy at the distance of 17.320 5 m with the positioning error of 0.002 3 m. | Geomagnetic Observations for Main Field Studies: From Ground to Space | Abstract The results of magnetospheric plasma fluxes measurement in geosynchronous orbit are presented. The measurements were done onboard the geosynchronous Russian “Electro” spacecraft (SC) in 1995–1997 years. The diurnal variations of the plasma density and temperature were observed at various levels of geomagnetic activity. Distortions of the measured electron and proton spectra caused by negative potential of the charged SC were registered. Typical electron spectra and plasma parameters were determined for various SC charging levels. Similar measurements in low polar orbits at the “Meteor” SC (launched in 2003 year) and the “Universitetskiy–Tatyana” SC (launched in 2005 year) were done. |
1,999,794 | New Results for Directed Vesicles and Chains near an Attractive Wall | We compute the elastic interaction between two identical conical inclusions in a spherical vesicle. We find it always repulsive and proportional to the square of the contact angle. At small angular separations Θ it decays as Θ−4, as in the case of planar membranes. After a crossover Θc ~ ψ0.54, where ψ is the inclusions' aperture, it decays as Θ−0.33, yielding a much stronger force than in a flat membrane. Finally, a quadratic minimum around the anti-polar configuration Θ = π is reached. | Toroidal membrane vesicles in spherical confinement | Vesicle deformation by an axial load: From elongated shapes to tethered vesicles | We present a numerical method to simulate vesicles in fluid flows. This method consists of writing all the properties of the membrane as interfacial forces between two fluids. The main advantage of this approach is that the vesicle and the fluid models may be decoupled easily. A level set method has been implemented to track the interface. Finite element discretization has been used with arbitrarily high order polynomial approximation. Several polynomial orders have been tested in order to get a better accuracy. A validation on equilibrium shapes and “tank treading” motion of vesicle have been presented. | I consider a vesicle with an open pore of small radius rp, exposed to a DNA solution. The crucial moment is the entry, when a chain end faces the pore and enters it. I discuss qualitatively the following three characteristic times: (i) the duration of the entry of one chain end (defining the minimum lifetime of the pore) τe ∼ 10−4 sec, (ii) the transfection time τt (the time required to be sure that one chain has gone in) τt ∼ hours, and (iii) the sliding time τS (the time between entry of one end and entry of the other end) ∼ 1 sec. A fortunate feature is that sliding may proceed even if the pore tends to close itself after entry. | Optical Torque Induced on the Geometrically Anisotropic Multi-Lamellar Vesicle with Form Birefringence | The observed flow enhancement in highly confining geometries is believed to be caused by fluid velocity slip at the solid wall surface. Here we present a simple and highly accurate method to predict this slip using equilibrium molecular dynamics. Unlike previous equilibrium molecular dynamics methods, it allows us to directly compute the intrinsic wall-fluid friction coefficient rather than an empirical friction coefficient that includes all sources of friction for planar shear flow. The slip length predicted by our method is in excellent agreement with the slip length obtained from direct nonequilibrium molecular dynamics simulations. | Two-dimensional vesicles subject to osmotic pressure imbalance may be modeled as unrestricted random rings. Assuming a pressure that couples to the square of the oriented area we are able to obtain an exactly solvable model that accommodates the deflated regime corresponding to a shriveled vesicle. Moreover, we investigated the effects of a long-range repulsive, nonlocal interaction among monomers by employing a variational approach. We find good agreement between our analytical predictions and Monte Carlo simulation results | 1,999,794 | Exact solution of a model of a vesicle attached to a wall subject to mechanical deformation | Parametrization invariance and shape equations of elastic axisymmetric vesicles | Deformation of a tensile membrane adjacent to a moving wall caused by viscous flow | Microfluidic velocimetry with near-wall resolution | W e develop coarse-grained particle approaches for studying the elastic mechanics of vesicles with heterogeneous membranes having phase-separated domains. We perform simulations both of passive shape fluctuations and of active systems where vesicles are subjected to compression between two plates or subjected to insertion into narrow channels. Analysis methods are developed for mapping particle configurations to continuum fields with spherical harmonics representations. Heterogeneous vesicles are found to exhibit rich behaviors where the heterogeneity can amplify surface two-point correlations, reduce resistance during compression, and augment vesicle transport times in channels. The developed methods provide general approaches for characterizing the mechanics of coarse-grained heterogeneous systems taking into account the roles of thermal fluctuations, geometry, and phase separation. | We apply the Bogomol'nyi technique, which is usually invoked in the study of solitons or models with topological invariants, to the case of elastic energy of vesicles. We show that spontaneous bending contribution caused by any deformation from metastable bending shapes falls in two distinct topological sets: shapes of spherical topology and shapes of non-spherical topology experience respectively a deviatoric bending contributionà la Fischer and a mean curvature bending contributionà la Helfrich. In other words, topology may be considered to describe bending phenomena. Besides, we calculate the bending energy per genus and the bending closure energy regardless of the shape of the vesicle. As an illustration we briefly consider geometrical frustration phenomena experienced by magnetically coated vesicles.PACS numbers: 87.16.Dg, 75.10.Hk, 11.27.+d Our motivation is to amplify on the observation of vesicles with arbitrary low genus (number of holes/handles) exhibiting conformal diffusion (spontaneous conformal transformation), namely existence of two conservation laws for vesicles[1][2][3][4][5][6]. The genus is a topological invariant: a quantity conserved under smooth transformations which does not depend on the static or dynamic equations of the system under consideration. In contrast, conformal diffusion provides evidence that the system Hamiltonian is invariant under conformal transformations. Whereas the Noether theorem[7,8]may be used to treat the latter invariance law in order to compute the corresponding conserved current and constant charge, the Bogomol'nyi technique enables one to treat successfully various models with topological invariants[9][10][11]. In this Letter we focus on the topological conservation law only; we defer the conformal diffusion to future articles.To obtain the Bogomol'nyi relationships we write down for vesicles of arbitrary genus a bending Hamiltonian as a covariant functional invariant under conformal transformations which depends on their shape only and which is suitable for the Bogomol'nyi decomposition. Applying the converse of the remarkable theorem of Gauss [12] enables us to construct such an Hamiltonian. Instead of describing shapes by their Monge representation (i.e., their surface equation) as customary [2, 3], we characterize shapes by their metric tensor and their shape tensor: the total integral of the shape tensor self-product is our successful candidate. Then the Bogomol'nyi | Dynamics of Three-Dimensional Vesicles in DC Electric fields | We determine stability boundaries for the wrinkling of highly unidirectionally stretched, finely thin, rectangular elastic sheets. For a given fine thickness and length, a stability boundary here is a curve in the parameter plane, aspect ratio vs. the macroscopic strain; the values on one side of the boundary are associated with a flat, unwrinkled state, while wrinkled configurations correspond to all values on the other. In our recent work we demonstrated the importance of finite elasticity in the membrane part of such a model in order to capture the correct phenomena.Here we present and compare results for four distinct models: (i) the popular Föppl-von Kármán plate model (FvK), (ii) a correction of the latter, used in our earlier work, in which the approximate 2D Föppl strain tensor is replaced by the exact Green strain tensor, (iii) and (iv): effective 2D finite-elasticity membrane models based on 3D incompressible neo-Hookean and Mooney-Rivlin materials, respectively. In particular, (iii) and (iv) are superior models for elastomers. The 2D nonlinear, hyperelastic models (ii)-(iv) all incorporate the same quadratic bending energy used in FvK. Our results illuminate serious shortcomings of the latter in this problem, while also pointing to inaccuracies of model (ii) -in spite of yielding the correct qualitative phenomena in our earlier work. In each of these, the shortcoming is a due to a deficiency of the membrane part of the model. _____________________________________________________________________________________________ | Change of the Willmore energy under infinitesimal bending of membranes |
1,999,795 | Its great to carry this when wearing something black and sleek | I keep this in my car for personal protection. And let me tell you, just by the looks of it, noone will want to mess with you. Classic black color, has a good weight to it. Love it | Really good for carrying not very visible accept the the clip but that's why its black so if you wear dark close its not very visible | Pros:
-Holds a lot
-Good for the money
-Has another strap so more than one way of carrying it
-Roomy
Cons:
-Wish there was a black.
Why I gave it five stares:
When it arrived I was so excited! When I opened the package I thought "oh no" it looked so small. I opened it up and to my surprise it was actually really big. It looks small but fits a lot of containers. I could fit 3 containers that are pretty big. I love it! I wish there was a solid black. but I choice the one closest and I love it. | Let me explain: A couple days ago at the dealership when I bought my bike, I told the guy who helped with the paperwork that I have all my gear already, majority of it is white/red and i have a reflective vest for night. He says, “Well they don’t see or look at you either way. I wear all black gear and I’m alright. Visibility doesn’t really matter, it’s up to the rider to make sure they’re safe.” I couldn’t help but kinda turn my head at that you know? Wouldn’t you think that *because* you aren’t paid attention to, that you’d want to at least to try be somewhat visible? I wanna hear you guys’ opinion on it lol. I can understand it, but I wouldn’t wanna go all black gear just yet. Specially in California.
Edit: Look dudes. I’m just asking for opinions, I know wearing all black makes you even less visible to those around you. | I was initially afraid this would be too bright, that the glimmer would look cheap. Nothing could be further from the truth. This is an outstanding Clutch with subtle colors and just the right touch of shimmer. It is large enough to carry what you need but not too large or bulky. Whatever the color you are wearing, it will pick up that tone and coordinate beautifully. Very happy with this purchase. | I'm loving this holster for conceal carry. I use it mostly when I wear suits and don't want the slightly bulkier Uncle Mikes that I own. There really isn't an option out there that is slimmer and more concealing than this. The main downside for me is that I don't like to wear it when I'm going to be outside for extended periods because I tend to sweat on the gun. I usually prefer a layer of protection between me and the gun on hot days. Overall, this is a great buy. | Love this rain jacket and how functional it is! Comes in handy for festivals and sporting events! I also have it in black. Get tons of uses out of it. And love how it folds up into a fanny pack! Get tons of complements each time I wear it! | Hey all, I hope this isn't too nebulous a question, but I'm trying to think of a strap design that would suit a Mondaine face and look fairly minimal, but also go nicely with either a black or brown belt and shoes--without needing to straight-up swap between black and brown bands all the time.
Basically, I had a black Hirsch with red stitching, which I felt was a nice in-between that wouldn't look out of place whether I was wearing black jeans/trousers and shoes, or tan suede and various colours of jeans. I'm just wondering what people's opinions are on strap types and colours which would complement the simple design nicely?
I suppose I could always go with a solid red strap, but I'm not sure how effeminate it'd look and any other solid colours and patterns might look woefully out of place.
Again, sorry if this is a stupid question--I'm hoping to get a few different opinions on the matter! | 1,999,795 | The is sooooooo sexy. Its great to carry this when wearing something black and sleek, it adds to your outfit. | this thing makes me look good and makes me feel sexy when I wear it | This is a gorgeous dressy jacket which looks great over a black top and pants | I like it. It looks cute over leggings, just not a true black | Love it. Wore it with a black tank top ... | I love it so much that I don't wear it | it is perfect and i feel glamorous wearing it | it looks fantastic, is amazing when i wear it how everytime ... | I liked it. But if you wear it all the ... |
1,999,796 | what is the best job to do in japan? | What is the major job in Japan? | Who are some famous poeple in japan? | Sparce resouce in japan? | ['Convenience. Like many Asian countries, Japan is surrounded by convenience. ... ', 'Transportation is expansive and efficient. It is easy to live in Japan without a car. ... ', 'Food is delicious. ... ', 'Shopping is great. ... ', 'Healthcare is top rate.'] | What are some japaneses cultural achievements? | Hello! I´m a 21 years old argentinian woman and i always been a japanese culture fan.
I studied the past three years digital and traditional 2d and 3d animation. I have to do my thesis this year to graduate.
I want to know how to introduce me and manage my portfolio to apply jobs in Japan, in or out the animation company (i´m okay with another kind of jobs that has nothing to do with my career for the moment.)
I will appreciate all the information you can give me, this year will be my first without studying and i want to prepare all the things possibles to my travel. Thank you.
**TL;DR:** How can i get an art or popular job in Japan being a foreigner woman? | Hello everyone glad to join this sub reddit.! I am entering my final year in Bachelor's Degree in Applied Archaeology and am looking about the possibility of any opportunities in Japan as it is a country I would love to experience for a couple of years! I have completed a module in GIS and have really liked working with it. I am wondering are there many work opportunities in Japan using GIS either in the archaeological discipline or something similarly related? Also what are the opportunities like in archaeology fieldwork? I understand I am at a big disadvantage as I cannot speak Japanese, but hope to learn some in the meantime if I find out there are are viable prospects of working in this wonderful country. Any help or information is greatly appreciated | What do japans people do for fun? | 1,999,796 | ['English teaching is still the most popular job for foreigners in Japan © JESHOOTS.COM / Unsplash. ... ', 'The IT field is another popular job type © Kevin / Unsplash. ... ', 'Interpreters can work freelance in addition to their day job © rawpixel.com / Unsplash. ... ', 'Sales is another popular job field © kulinetto / Pixabay.'] | What are major jobs in Japan? | Any foreigner (non-Japanese) here with a non-teaching or IT job in Japan? | Working & Living in Japan as an Engineer | Entry-level Engineering jobs in Japan? | What's a good place to find a summer job in Japan? | Jobs in Japan for japanese citizen engineer NOT fluent in japanese | Mid career professional and moving to Japan | Will be getting laid off, any good places to look for work for foreigners? (I use gaijinpot, dajiob) |
1,999,797 | in what year was composer richard niles born | He died in Barry, aged 79, and is buried in Merthyr Dyfan cemetery. John Morgan Lloyd John Morgan Lloyd (19 August 1880 – 30 June 1960) was a Welsh musician and minor composer. As a composer, he is best known for his hymn tunes, including "Pro Nostris Liberis", and was a representative of Wales on the committee for the 1927 revision of the "Church Hymnary". He was born at Pentre in the Rhondda Valley, the son of a men's outfitter. His family were founder members of Penuel Welsh Calvinistic Methodist Church, in High Street, Barry, where they lived from 1889; | was nominated for four Grammy Awards for his work with Chic, Sister Sledge, Diana Ross, and Robert Palmer. On September 19, 2005, Edwards was honored posthumously for his outstanding achievement as a producer, when he was inducted into the Dance Music Hall of Fame at a ceremony held in New York. Bernard Edwards Bernard Edwards (October 31, 1952 – April 18, 1996) was the American bass player, singer, songwriter and record producer, known primarily for his work in disco music with guitarist Nile Rodgers, with whom he co-founded Chic. In 2017, Edwards was selected as the 53rd greatest bassist of | Nile Water (French: L'eau du Nil) is a 1928 French drama film directed by Marcel Vandal and starring Jean Murat, Max Maxudian and Lee Parry. Originally made as a silent film, it subsequently had a musical soundtrack added to it. It was the first French sound film, shot using a system owned by Gaumont. However, the system never took off and American and German technology came to dominate.
The film's sets were designed by the art director Fernand Delattre.
Main cast
Jean Murat as Pierre Levannier
Max Maxudian as Wirsocq
Lee Parry as Anne Marie
René Lefèvre as Arthur de Sorgepoix
Gaston Jacquet as Basil Lescoe
Anita Labartha as Danseuse
References
Bibliography
Crisp, C.G. The Classic French Cinema, 1930-1960. Indiana University Press, 1993.
Kindem, Gorham Anders. The International Movie Industry. SIU Press, 2000.
External links
1928 films
French films
French-language films
Films directed by Marcel Vandal
French black-and-white films
1928 drama films
French drama films
Films set in Egypt | African Sanctus African Sanctus is a 1972 choral Mass and is the best-known work of British composer and collector of world musics David Fanshawe. In "African Sanctus" the Latin Mass is juxtaposed with live recordings of traditional African music, which the composer had recorded himself between 1969 and 1973 during a journey up the Nile, from the Mediterranean Sea to Lake Victoria. The work consists of 13 movements and follows the journey of the composer through Africa. The recordings are from Egypt, the Sudan, Uganda and Kenya. A key moment in the conception of "African Sanctus" came at the beginning | Salzedo. Salzedo's then-wife Lucile Lawrence, also a harpist, was personally instructed by Ravel in the performance of the work. Later recordings include: The work was also performed on television, on the 23 December 1963 edition of Leonard Bernstein's "Young People's Concerts". Introduction and Allegro (Ravel) Introduction and Allegro for Harp, Flute, Clarinet and String Quartet () was written by Maurice Ravel in 1905. It premiered on 22 February 1907 in Paris. To showcase its new chromatic harp, the Pleyel company commissioned Claude Debussy in 1904 to write his "Danse sacrée et danse profane" for harp and orchestra. The Érard company | and "High Tide at Noon". Some of his film scores were later destroyed by the film studios. He wrote in a tonal idiom and suffered under the avant garde musical regime at the British Broadcasting Corporation headed by its Director of Music William Glock and almost ceased composition in the 1960s. Following his re-discovery in the 1980s he resumed composing. His Violin Concerto is available on the Chandos CD label, played by Lydia Mordkovitch with Richard Hickox conducting the BBC Symphony Orchestra. It is coupled with the Violin Concerto of Benjamin Britten. John Veale died in Bromley, Kent (a south-eastern | William Billings William Billings (October 7, 1746 – September 26, 1800) is regarded as the first American choral composer. William Billings was born in Boston, Massachusetts. At the age of 14, the death of his father stopped Billings' formal schooling. In order to help support his family, young Billings trained as a tanner. He possibly received musical instruction from John Barry, one of the choir members at the New South Church, but for the most part he was self-taught. Billings had an unusual appearance and a strong addiction to snuff. His contemporary wrote that Billings "was a singular man, of | music with the newest foreign Western musical techniques. With these songs and many others, he is recognized by most of his fellow musicians, including Umm Kulthum, Zakariyya Ahmad, and Mohammed Abdel Wahab, as being the master of the new music spirit. And below is a list of some of his famous works Mohamed El Qasabgi Mohamed el-Qasabgi (; pronounced [in the Egyptian dialect] el-Asabgi; 1892 – 25 March, 1966) was an Egyptian musician and composer, and is regarded as one of the five leading composers of Egypt in the 20th century. Most of his credits went to Umm Kulthum, Asmahan, | 1,999,797 | Richard Niles Richard Niles is an American composer, arranger, record producer, guitarist, broadcaster, and journalist. He has lived in London since 1975. Because of his extensive work across many genres, "Sound on Sound" magazine referred to him as "one of the most versatile men in modern music". Jazz guitarist Pat Metheny wrote, "Richard Niles is one of the best composer/arrangers around and an exciting musical force." Paul McCartney wrote, "Richard Niles is a great orchestrator and musician and was a great pleasure to work with." Niles was born May 28, 1951, in Hollywood. He is the son of Tony Romano, | what was the name of the orchestra that bing crosby played with eddie | when did mr tambourine man first perform in london | composer roger nixon was born in which us state | who duetted with harold ashby on earl haines | what was the birth date of composer richard rodgers | who was the father of jazz pianist jeremy davenport | who did paul willson play in frasier | phil harper was the voice of harry nile in which radio series |
1,999,798 | What are some of your favorite darkweb/onion forums? | What are some other websites similar to disboard? Where u list ur server and stuff? | One of the best environments I've been in was the onision forum. Unfortunately it's down so it can't be used. So what was the best forum environment you've been in? | I'm tired of the memes and this summer has brought on way too many kids. What's a good site that's similar to reddit but for more mature users?
I can think of Hacker News and Metafilter. I'm almost thinking about looking at Digg even though I left there four years ago. I've heard that since most of the users left, it's actually not bad anymore. | I know r/seo and r/bigseo. Where would you guys recommend to become better and to learn "secret"? Even paid forum would be nice since there would be less noise.
Thanks. | What are forums? | I lurk various forums quite a bit via search, but have never actually registered or posted in one. HDforums.com comes up a lot but has a LOT of ads and other BS. ChopCult forums seem pretty good, and recently someone turned me onto JockeyJournal.com…aside from Reddit, which forums do you actually post and participate in? | WHAT the most popular websites on the net? | What WoW websites do you regularly use and recommend? I'm recompiling our list of related subreddits](/r/wow/wiki/related) and [websites, and I'd love to add in new information.
Got something interesting to put here? Let me know! Are you interested in helping to curate said list? let me know! | 1,999,798 | Rather it be dark markets, hell, off topic, darkweb discussions, or just how to's... What are the popular ones and what are your favorite? | Why Dark Themes Seem To Be So Popular? | Recommendations for places to discuss blockchain | Intresting Dark Web site designs? (For my Game) | So DnD is pretty popular around here. What other systems do redditors enjoy regularly? | what is the name of the darknet market in open bazaar | Bitcoinwidsom.com hidden markets? | What are the top five most popular webkinz? | Suggestion : periodical discussion or q&a threads for purely technical aspects of bitcoin/cryptocurrency. |
1,999,799 | I am a guy who just watched a full length porn for the plot. | What porn do men watch? | Is it normal for a 12 year old to watch porn? | Does porn bad for you? | Why watch porn movies? | me and some female friends talked a little about porn, all three of them said that they loved watching forced orgasm and even some type of rape-porn.
This fucking blew my mind, I thought rape-porn was something some sick guys that consumes 10 000 DVD-porn movies a year likes or something.
Is it really that normal? | Yesterday, my girlfriend asked how much porn I watch. When this question has been subtly hinted at before, I denied and dismissed. She went on to say "come on, just tell me. I know all guys watch porn." While this is almost universally true (I'm sure not *all* do, but a good amount), I feel like it's a trap. Do you tell your significant other if you look at porn, or do you deny? Do they even ask? | I was watching porn and wondered if there was high porn. That would be awesome! | I just love a good story rather than just blatant porn. Are there any good short films that have a story but also do not shy away of showing some skin, erotic or not?
Definitely not wanting something that only calls itself a short film but actually is just a glorified porn movie.
Don't get me wrong, I also enjoy the completely prude short films that only hint at what is going on and the camera pans away from the cock, but I know there are a lot of good gay sex scenes in short films that are more art than porn.
Thanks in advance. | 1,999,799 | I thought it would be interesting to watch a porn (Revenge of the Petites) with no sexual ties. Honestly, I enjoyed it. The acting was decent enough and the jokes as good as an American Pie movie. Ask me anything about my experience or otherwise. | Do you enjoy the cheesy build up in porn? And would porn be a different experience without that Intro? | Intimate porn to watch with wife | Any of you seen “Theatre of Blood” with Vincent Price? | Do you ever watch porn and, after climax, immediately start comparing yourself to the actors? | To those of you who have gone to a Hollywood premiere of a really bad movie, what was it like? Was the atmosphere embarrassing or was everyone high-fiving each other. | Am I the only person on Earth that enjoyed the movie LIFE? | A few good scenes still focusing on cheap slobbery sex scenes no ... | I enjoyed the gentle feeling of the film i |
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