There are many good uses that you could consider this garden room for, in addition to your primary reason for choosing this cabin, the Garden Room Linda will brighten up your garden and will be the focal point and star of all garden parties. DIY assembly is easily achievable within two days or you can use our fitting services and have your garden room built within a day. All four wall high windows open. Double glazed doors and windows, 44mm wall planks and 28mm floor boards are included in the standard price.
Additional information: Treated foundation joists, wind braces, assembly kit, real glass in windows and doors, cylinder lock, product manual, 5 years guarantee. Cat: log cabins for self assembly.


text:
Kodi Smit-McPhee
Birthdate: 13th June, 1996
Birthplace: Sydney, Australia
From Wikipedia, the free encyclopedia Kodi Smit-McPhee (born 13 June 1996) is an award-winning Australian actor, most known for his roles as The Boy in the The Road and Owen in Let Me In. He has also appeared in Australian films, Romulus, My Father and Matching Jack.
Kodi Smit-McPhee (born 13 June 1996) is an award-winning Australian actor, most known for his roles as The Boy in the The Road and Owen in Let Me In. He has also appeared in Australian films, Romulus, My Father and Matching Jack.
Alpha (2018)
After a hunting expedition goes awry, a young caveman struggles against the elements to find his way home.
A group of scientists in San Francisco struggle to stay alive in the aftermath of a plague that is wiping out humanity, while Caesar...
In the town of Blithe Hollow, Norman Babcock is a boy who can speak to the dead, but no one besides his eccentric new friend, Neil,...
Let Me In (2010)
This is a remake of the movie "Let The Right One In" which was a movie adaptation of a book. A story of a young boy who is frequently...
A father (Viggo Mortensen) and son make their way across a post-apocalyptic United States in hopes of finding civilization amongst the...

redpajama_set_name: RedPajamaCommonCrawl


Here's the great thing about "American Vampire" #20. Never mind that it's part 2 of 3 and the middle of a storyline. The first half of this issue is so strong that I reckon you could give it to any new reader and they'd be so entranced that they'd stick around for the rest of the series.
Scott Snyder opens the new issue of "American Vampire" with a flashback to an expedition to find the western shore, one that bears a striking similarity to Lewis and Clark's infamous trip across the country with Shoshone guide, Sacagawea. But like so many things in "American Vampire," what looks simple and ordinary is of course anything but. As Snyder uses his Sacagawea analogue as the narrator for this portion of the issue, he brings a sense of creeping dread over the comic. You know it isn't going to end well, the only question is for whom. And even when the big reveal finally appears and we discover the hidden secrets of the expedition, Snyder still has some surprises. Honestly, though, if you read through page 14 and stopped, you'd feel like you got a full issue's worth of story and would be more than satisfied.
But of course, there's more to the issue. As it ties into the events of the previous chapter, it not only makes "The Beast in the Cave" feel that much richer and more interesting, but it makes the situation of Skinner and Book more precarious and dangerous. The specter of Mimiteh and what it means for the cavalry, the tribe, and even Skinner and Book gives a punch to the story, and makes the cliffhanger toward next month's conclusion that much stronger.
It doesn't hurt, of course, that Jordi Bernet is illustrating this three-part story. While I adore co-creator Rafael Albuquerque's art on the title, Bernet is knocking his pages out of the park. I love the almost woodcut nature of the illustrations of the expedition, with the hunters being hunted as they creep through the woods, or how the self-described "nightmare come to life" in fact feels like just that, erupting into violence and horror. Bernet is a living legend, a true gem of comics, and there are no throw-away panels here. From the leap of the monster under the moonlight, to the final climactic moment of this issue, there's so much energy and expression that it's a little boggling.
"American Vampire" is consistently strong, month after month, so it's with that already in mind that I say that this is probably my favorite issue to date. There's something about that retelling of the Lewis and Clark expedition into "American Vampire" lore that makes it extra entrancing. Whatever that is, I'm not complaining. You don't get much better than this.


• Large estate with stables, riding arena, guest house, treatment centre, meadow and challenging routes to ride.
• Breed cute little foals (over 100 possible combinations), train them on the lunge and then sell them to horse lovers.
• Pamper your horses with curry combs, massages, showers and by cleaning their hooves.
• Demonstrate your riding skills on challenging cross-country rides.
• Gallop at full speed and handle the fabulous jumps on 9 riding courses and in the open.
• Exciting horse races through stunning countryside.
• Comprehensive business section with the aim of running the best stud farm in the world.
My Riding Stables - Life with Horses © 2018 Markt+Technik Verlag GmbH. Developed by Independent Arts Software GmbH. Published by Kalypso Media USA. All rights reserved.


Boasting one of the largest research university libraries in the Southeast, Carolina is consistently ranked as having one of the top 20 libraries in the nation. The University is home to an array of books, archival material, digital resources and multimedia holdings, many of which cover global topics or are available in a foreign language.Library staff with expertise in global and area studies field reference questions, support visiting scholars and international visitors, bolster international research with collections and engage with local and global communities. UNC's library system consists of many collections and libraries, including Davis Library, the Health Sciences Library, the Wilson Special Collections Library and the Law Library.
The library system actively builds specialized collections devoted to East Asian studies, Latin American and Iberian studies, Middle Eastern and Muslim Civilizations, and Slavic, Eurasian and East European studies.
Students and faculty may check out DVDs or stream online foreign language films from the Media Resource Center of the R.B. House Undergraduate Library, which features a collection in the thousands.
Language-learning resources such as audiobooks, kits, e-books, study guides and phrasebooks allow students to supplement their in-class language learning or enable ambitious students to pick up a new language in their free time.
Online tutorials on topics such as study abroad and Latin American studies research provide students with additional resources. E-research guides provide handy identification of databases, online journals and websites devoted to global regions and subjects across all disciplines. The Study Abroad Tutorial can prepare and assist UNC students studying abroad, with resources to research destination countries, travel tips, language resources and more.
The International Government Documents section gets publications from over 50 international intergovernmental organizations, such as the United Nations, European Union, Organization of American States, etc. You can also find information about world countries, international organizations and more.
An agreement between North Carolina State University, North Carolina Central University, The University of North Carolina at Chapel Hill and Duke University has created the Triangle Research Libraries Network. Students, faculty and staff at any of the network schools may borrow books and resources from participating universities, further expanding the inventory of available resources.
Whatever their interest or research topic, Carolina students have access to a world-class education with worldwide resources available at their fingertips through the UNC Libraries.


text:
DISCOURSE XVI.
THE SECOND GENERAL DESCRIPTION : OR, THE GREAT RED DRAGON,
AND THE WOMAN FLYING INTO THE WILDERNESS.
Chap. xii. 1-6.
The first general description, it has been observed, took up the apostasy at the time when things were so matured that the Catholic church was ordered to be left out of God's temple, as not belonging to it : but this appears to trace it to its origin. Here we go back to an early period of history ; possibly as far as to the fourth century, and to the times of some of the first trumpets. At a time when the church was in danger of being lost in superstition and worldly conformity, it was natural for the faithful to feel anxious for the cause of Christ. For their encouragement, the church is described in vision as bearing a seed wbich should be preserved by the special care of heaven, through all these evil times, and be. come in the end victorious over the whole earth. Such appears to be the scope of this second general description. Vol. VI.
1 And there appeared a great wonder in heaven ; a woman clothed with the sun, and the moon under her feet, and upon
her head a crown of twelve stars : 2 And she, being with child, cried, travailing in birth, and pained to be delivered. 3 And there appeared another wonder in heaven ; and behold, a great red dragon, having seven heads, and ten horns, and seven crowns upon his heads. 4 And his tail drew the third part of the stars of heaven, and did cast them to the earth ; and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born. 5 And she brought forth a man-child, who was to rule all nations with a rod of iron : and her child was caught up unto God, and to his throne. 6 And the woman fled into the wilderness, where she hath a place prepared of God, that they should feed her there a thousand two hundred and threescore days.
Prior to the introduction of antichristian corruptions, the church is described as "a woman clothed with the sun, and having the moon under her feet, and upon her head a crown of twelve stars ;"> denoting the plenitude of gospel light which compassed her as a garment; her superiority to the Jewish dispensation ; and, in consequence of her adherence to the doctrine and examples of the apostles, her triumph over ten successive persecutions.
The woman is said to be " with child, travailing in birth, and pained to be delivered ;" denoting, it may be, the earnest desires of the true church after the increase of believers. Such has always been its character. Worldly men, who have taken upon them the Christian name, have invariably been employed in compassing selfish objects. But true Christians have at all times been distinguished by a desire to extend the kingdom of Christ.
The following description, by EUSEBIUS, of the labours of the immediate successors of the apostles, is doubtless applicable to the church so long as it adhered to their doctrine and example.
They built up those churches the foundations of which were laid by the apostles, promoting greatly the doctrine of the gospel, and scattering the salutary seed of the kingdom of heaven at large over the whole world.-Travelling abroad, they performed the work of evangelists to those who as yet had not heard the word of faith, being very ambitious to preach Christ, and to deliver the books of the divine gospels. And these persons having only laid the foundation of faith in remote and barbarous places, and constituted other pastors, committed to them the culture of those they had perfectly introduced to the faith, departing again to other regions and nations, accompanied with the grace and co-operation of God." Lib. III. c. 37.
While the woman is thus in labour," behold a great red dragon, having seven heads and ten horns, and seven crowns upon bis heads, whose tail drew the third part of the stars of heaven, and did cast them to the earth, stands before her, ready to devour her child as soon as it was born." The dragon is in ver. 9. expressly called " the Devil and Satan, who deceiveth the whole world," and all that is said of him in the remainder of the prophecy agrees with this in its literal application : but by his having the heads and borns of the Roman beast, is intimated that it was under this form, or by means of this government, that he did what he did in the present instance.
As the woman is not an individual, but the society of the faithful, so neither is the man-child an individual, but the woman's seed, wbich in ver. 17th is explained of them who " keep the commandments of God, and have the testimony of Jesus Christ." It was this seed that the dragon aimed by persecution and corruption to destroy. This child was born to rule ; not however at present: for if so, there had been no need of his being caught up to the throne of God, nor for his mother's flying into the wilderness for 1260 years. It is at the termination of that period that the man-child, or the seed of the church shall rule; and this accords with Dan. vii. 27. "The kingdom and dominion, and the greatness of the kingdom under the whole heaven, shall be given to the people of the saints of the Most High." Nor need it be objected that the sceptre of this government is a rod of iron: for such the kingdom of Christ must ever be to the ungodly.
There are two marks by which the times referred to in this vision may, if I mistake not, be ascertained. One is the 1260 days, or years, which, being the appropriate number of the reign of the papal antichrist, proves it to have no reference to the times of paganism. The other is, that the ten horns are not upon the beast, but upon the dragon, and the crowns are not as yet upon them, but upon the seven heads. When the horns are spoken of in reference to the times following the overthrow of the empire by the northern nations, and of its becoming ten independent kingdoms, they are described as being upon the beast, and as having crowns upon them. Chap. xiii. 1. This indicates that the introduction of the vision contained in the first five verses of this chapter, though it does not go so far back as to the days of Paganism, yet neither does it go so far forward as to the times of Popery; but to those which were intermediate and preparatory, namely, the fourth and fifth centuries, in which Christianity became exceedingly corrupt, and a connexion was introduced between the secular and ecclesiastical powers, which issued in what is exhibited in Chap. xvii. a woman riding upon a scarlet-coloured beast! I do not suppose that the 1260 years of the reign of antichrist are to be reckoned from the time when these corruptions began. Antichrist did not commence his reign from his birth; but from thence his way was preparing. It is of what was done prior to the woman's flight into the wilderness for 1260 years that these verses, speak. By the accession of Constantine, the beast was as it were wounded to death ;" and this may be the reason why no mention is made of him. Under the Christian emperors the beast for some time would lie apparently dead : the dragon, however, " that old serpent the Devil and Satan, who deceiveth the whole world," knew how even at that time to make use of the
pomp and
power of the empire to serve his purposes.
It is in the corruptions of the fourth and fifth centuries that we are to look for the origin of popery. It was by the influx of worldly power and glory into the church that Satan first seduced a great part of those who had shone like stars in the Christian firmament, and, (alluding perhaps to his having originally drawn into apostasy a great part of the angels of heaven,) cast them to the earth. But perceiving, notwithstanding what has been done as to a number of the leaders of the church, that a large body of


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Email Jude Bailey Cert/Dip Person Centred Counselling & CBT.
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Learn what is mLearning, how to determine its need and how to design it.
The increase in the mobile device penetration has led to many changes in all spheres of our lives and has revolutionised the way we live and learn. Download this whitepaper to get a thorough understanding of this rapidly evolving technology.


Short story. Reminiscence by the 85-year-old playwright about his relationship with the movie director Ernst Lubitsch. The two worked on nine films together between 1930 and 1947, when Lubitsch died. Now, late in life, writer has begun to feel that Lubitsch meant much more to him, and, perhaps, he much more to Lubitsch than he has ever taken the time to realize. Raphaelson knew and cared little about movies (his love was the theatre, for which he first wrote "The Jazz Singer") and Lubitsch was no writer, but the two worked well together. Writer admits, however, that the two were never very close. Raphaelson was disappointed when Lubitsch married Vivian Gaye, and he saw little of Lubitsch until that marriage failed. In 1942 Lubitsch and Raphaelson collaborated on "Heaven Can Wait" ("a blithe experience"). The next year, the director suffered the first of a number of heart attacks. Thinking Lubitsch on the verge of death, and realizing his love for the man, Raphaelson wrote a beautiful eulogy for him. When Lubitsch survived, Raphaelson locked the piece away and swore his secretary to secrecy about it. In 1947, as they finished writing their last movie, "That Lady in Ermine," Lubitsch said he had read and "liked" the eulogy. Embarrassed, Rafe protested that it was only a first draft. Then director and writer proceeded to rewrite the piece. As they worked and talked the two experienced a moment of unprecedented closeness. In the end Lubitsch decided he liked the original best and asked Rafe to promise to keep it exactly as he first wrote it. After Lubitsch's death, in November, 1947, the piece did run, in "The Screen Writer," in its original form. Intact, even, was the part in which Raphaelson regrets his not telling Lubitscht of his feelings while the director was still alive. The writer admits that the current piece shows his eulogy to have lied on that count.


Monday, August 11 at 5 PM is the night for a Family Movies Sing-Along at the Northgate Branch Library. Children are encouraged to bring pillows to sit on the floor; popcorn will be supplied by the library. The movie for Monday, August 11th, is Mary Poppins, a musical famed for its production numbers of singing and dancing and a chalk-drawing episode which comes to life. Prior to the start of the film, children will be invited to do chalk-drawing on the sidewalks surrounding the library.
The Northgate Branch Library is at 10548 Fifth Ave NE.
Other Movie Sing-Alongs will be The Little Mermaid on August 18, and Frozen on August 25. The Northgate Branch Library is at 10548 Fifth Ave NE, across the street from the Macy's side of the Northgate Mall. Suggested driving directions from Wedgwood are to travel straight west on NE 75th Street, continuing on Banner Way NE to the intersection of 5th Ave NE. Turn right on Fifth Ave NE and travel straight north to the library at NE 105th Street.
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text:
Q: Forward using types in classes in C++ I'm trying to forward access enums inside classes as below:
class city;

struct retro
{
   int num_blocks;
   city::street strt;  // <- city::street unknown type
};

class city
{
   public:
    enum street
    {
       MAIN,
       FIRST,
       SECOND
    };
   private:
    ...
};

Is this not a valid way of doing it? What am I doing wrong here?
I fixed the problem this way:
class city_basic
{
   public:
    enum street
    {
       MAIN,
       FIRST,
       SECOND
    };
};

struct retro
{
   int num_blocks;
   city_basic::street strt;  // <- works fine
};

class city : public city_basic
{
   ...
};

Is there a better way of solving this?

A: The standard requires that city being a complete type at that point.
Basically any time you declare a variable, field of a type or accesses it's members the type has to be completely declared. The rationale is that the compiler will have to know the size of the object at that point (or in the case of accessing members know the layout).
You can on the other hand define a pointer  before the type is completely defined, but still you can't do pointer arithmetics or access members via the pointer (the compiler needs to know the size or layout for that too).

A: If it is not possible to define city before retro, it may be better to define enum city::street outside of the class:
enum city_street { MAIN, FIRST, SECOND };

struct retro {
    int num_blocks;
    city_street strt;
};

class city {
    ...
};

redpajama_set_name: RedPajamaStackExchange


text:
Did Twitter Files Just EXPOSE Michelle Obama for Trump's Twitter Ban?
by Staff Reports December 12, 2022, 3:31 pm 5.7k Views
According to a report from Fox News, former First Lady Michelle Obama demanded that Twitter remove President Donald Trump from its platform and he was banned the next day.
The fourth batch of Twitter documents, which included internal communications, was released by CEO Elon Musk on Saturday. These documents show that the company's executives discussed the situation in Washington DC following the riot at the Capitol Building on January 6, 2021.
In one of the files, Shellenberger noted that various external and internal pressures led to the company calling for Trump's removal from Twitter.
In a statement posted on Twitter, Obama called on tech companies to stop enabling the "monstrous behavior" of the president and called for them to implement policies that prevent their platforms from being used by the government to "fuel insurrection."
Several prominent organizations and individuals, including the Anti-Defamation League, also called for Trump's removal from Twitter.
In response, Jack Dorsey, Twitter's CEO, sent an email to employees on January 7. He told them to follow the company's policies and continue to be consistent with them. At that time Trump was just suspended from Twitter.
According to the documents, Twitter maintained a policy that allowed elected officials to remain on the platform even if they violated other policies. This policy, known as the Public-interest exceptions, was designed to allow the public to see what officials were saying.
During his vacation in French Polynesia from January 4 to 8, 2021, Dorsey was away from the company. He delegated some of the responsibility to several senior executives, such as Yoel Roth and Vijaya Gadde.
Shellenberger noted that in 2020, almost all of Twitter's political donations went to the Democrats. In 2022, almost all of the company's political donations went to the Democrats.
Despite knowing the difference between Twitter's Terms of Service and its political content, the company's employees still carry out complex interpretations of the content to determine which posts are prohibited.
After Dorsey's email, Trump was removed from Twitter for violating the company's rules. This was because his posts were being interpreted and received poorly.
After Elon Musk took over as the company's CEO, Trump's access to Twitter was restored. However, he has not yet resumed control of his account. He reaffirmed his intention to remain on Twitter and continue to use its platform, known as Truth Social.
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I agree with what you wrote that using one name (Eddington) throughout is less confusing and leads to greater continuity for the reader…Very interesting this process of creative writing!
Thanks Denise. Of course not eveyone does it the same, but it's fun to share because I'm a novice. Maybe it will help someone else to not hesitate to write themselves!


text:
Q: What is the difference between a .NET framework DLL and a .NET core DLL? Why do they need seperate runtimes? When inspecting a .NET Core DLL and .NET Framework DLL using ildasm, they both seem very similar. The only difference I could see is the references (the .NET Framework DLL references mscorlib).
This makes sense, since both have to conform to ECMA-335. However, I don't understand how the runtime knows to use the .NET Core runtime, or .NET framework runtime when it loads a DLL for the first time. I also don't really see any reason why the .NET Framework wouldn't be able to run the .NET Core DLLs => as long as it can find the references, they must all be ECMA-335 DLLs.

A: There's not a real difference, which is why libraries compiled against .NET Standard can be run on both runtimes.
The differences are mainly that .NET Core libraries believe System.String comes from System.Runtime, and .NET Framework libraries believe it comes from mscorlib.  With proper type-forward shim assemblies both runtimes can run libraries compiled for the other one... right up until they get a MissingMethodException or a TypeNotFoundException because the library used something only available on one of the runtimes (new methods in .NET Core, or methods left out of .NET Core that are present in .NET Framework).
The runtime differences are more subtle:

*

*.NET Core doesn't have multiple AppDomains per process

*.NET Core has System.Span as a special type in the runtime for better performance

*.NET Framework has one GAC for 4.0 through 4.8

*.NET Core maintains individual copies of Shared Frameworks for each patch release (for app-specific version locking)

*.NET Framework GAC wins

*.NET Core app-local file wins

*.NET Core no longer uses CAS / partial trust

*etc


text:
Hopewell Theater's Holiday Programs & Holiday Hours
HT News
"I played the Hopewell Theater for the first time and was blown away by the experience." - Mary Gauthier, Grammy winning singer/songwriter "Thank you for coming to Hopewell Theater, they are doing an incredible job for the community in having this theater available for live music." - Max Weinberg, E Street Band and Hall of Fame Drummer "What a gorgeous venue. Beautiful theater, beautiful sound." - Lucy Kaplansky, Folk Artist "I really had such an awesome time - loved the staff, loved the crew, loved the vibe, loved everything!" - Comedian Jackie Byrne
Blog | News | Posted on December 20, 2019 at 10:54 am by hopewell
Celebrate the season with our Holiday Film Fest, a great way to experience Christmas classics on the big screen.
Feel the music with live performances by Pyrenesia, The Slambovian Circus of Dreams, and NRBQ, plus dance the night away with Philadelphia's swing band Parlour Noir during our vintage New Year's Eve party!
Hopewell Theater's Admin Office will be closed for the holidays on December 25 and January 1. The Box Office will be open December 25 after 5pm for the film screening that day.
Cozy up to our stage and screen with holiday live shows, films, and more! Our intimate theater is the best place to celebrate the festive season with family, friends, and neighbors.
Begin the festivities with our Holiday Film Fest, starting with SCROOGED, a modern, comedic take on Charles Dickens' "A Christmas Carol" on Dec 20 & 27, starring Bill Murray. On Dec 21 & 28 comes the 2000 live-action adaptation of Dr. Seuss' HOW THE GRINCH STOLE CHRISTMAS, a family-friendly holiday classic starring Jim Carrey as the Grinch. The ultimate romantic comedy, LOVE ACTUALLY, screens Dec 22 & 25, a film with an all-star cast and a dozen characters in an interwoven web of tales. On Dec 26 is everyone's favorite NATIONAL LAMPOON'S CHRISTMAS VACATION, starring Chevy Chase as the father in a quirky family whose holiday plans go awry. Ending the Holiday Film Fest with two film screenings on Dec 29, The Royal Ballet's THE NUTCRACKER is a gorgeous stage production of a quintessential Christmas tale.
Films aren't the only holiday programs we have this year!
Come to this weekend's family-friendly, danceable Holiday Shows featuring live music by Lambertville's gypsy jazz group PYRENESIA on Saturday, Dec 21 and New York's rootsy psychedelica, surreal Americana SLAMBOVIAN CIRCUS OF DREAMS on Sunday, Dec 22. Both performances will have a limited number of jambalaya dinners from The Peasant Grill for sale at concessions, first come first serve. Then, bring in the new year with a live music show on Dec 28 with NRBQ, a rollicking blend of everything from stomping rockabilly to Beatles-influenced pop to Thelonious Monk-inspired jazz.
Finally, on Dec 31 RING IN THE 20'S with our vintage New Year's Eve party! Featuring live swing music by Philadelphia's Parlour Noir and an optional three-course dinner by Brick Farm Tavern, this elegant trip back to the 1920's-40's includes a free coat check, party favors, cash bar, and a swing dance lesson from a pro. Vintage attire is encouraged! Get a free gift with purchase of two dinner tickets.
Plus, now through January 6, enjoy no ticketing fees on any live music or performance tickets you purchase during HT's Holiday Sale – buy four you get a discounted individual or dual membership.
Don't forget: through January 6, add a donation to your ticket purchase to "Give Hope" in support of HomeFront's mission to help families break the cycle of poverty. With your help, we've raised $300 so far! Help us give more to families in need this holiday season.
Be sure to sign up for our weekly e-blast below to stay in the loop of exciting program updates, concessions specials, and other deals!
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text:
Biological tissue-inspired tunable photonic fluid
Xinzhi Li, Amit Das, and View ORCID ProfileDapeng Bi
PNAS June 26, 2018 115 (26) 6650-6655; first published June 11, 2018; https://doi.org/10.1073/pnas.1715810115
Xinzhi Li
aDepartment of Physics, Northeastern University, Boston, MA 02115
Dapeng Bi
ORCID record for Dapeng Bi
For correspondence: d.bi@northeastern.edu
Edited by Andrea J. Liu, University of Pennsylvania, Philadelphia, PA, and approved May 15, 2018 (received for review September 7, 2017)
We design an amorphous material with a full photonic bandgap inspired by how cells pack in biological tissues. The size of the photonic bandgap can be manipulated through thermal and mechanical tuning. These directionally isotropic photonic bandgaps persist in solid and fluid phases, hence giving rise to a photonic fluid-like state that is robust with respect to fluid flow, rearrangements, and thermal fluctuations in contrast to traditional photonic crystals. This design should lead to the engineering of self-assembled nonrigid photonic structures with photonic bandgaps that can be controlled in real time via mechanical and thermal tuning.
Inspired by how cells pack in dense biological tissues, we design 2D and 3D amorphous materials that possess a complete photonic bandgap. A physical parameter based on how cells adhere with one another and regulate their shapes can continuously tune the photonic bandgap size as well as the bulk mechanical properties of the material. The material can be tuned to go through a solid–fluid phase transition characterized by a vanishing shear modulus. Remarkably, the photonic bandgap persists in the fluid phase, giving rise to a photonic fluid that is robust to flow and rearrangements. Experimentally this design should lead to the engineering of self-assembled nonrigid photonic structures with photonic bandgaps that can be controlled in real time via mechanical and thermal tuning.
photonic materials
tissue mechanics
bioinspired materials
Photonic bandgap (PBG) materials have remained an intense focus of research since their introduction (1, 2) and have given rise to a wide range of applications such as radiation sources (3), sensors, wave guides, solar arrays, and optical computer chips (4). Most studies have been devoted to the design and optimization of photonic crystals—a periodic arrangement of dielectric scattering materials that have photonic bands due to multiple Bragg scatterings. However, periodicity is not necessary to form PBGs, and amorphous structures with PBGs (5⇓⇓–8) can offer many advantages over their crystalline counterparts (7). For example, amorphous photonic materials can exhibit bandgaps that are directionally isotropic (9, 10) and are more robust to defects and errors in fabrication (7). Currently there are few existing protocols for designing amorphous photonic materials. They include structures obtained from a dense packing of spheres (3D) or disks (2D) (5, 11⇓⇓–14), tailor-designed protocols that generate hyperuniform patterns (9, 10, 14, 15), and spinodal-decomposed structures (16, 17). While these designs yield PBGs, such structures are typically static, rigid constructions that do not allow tuning of photonic properties in real time and are unstable to structural changes such as large-scale flows and positional rearrangements.
In this work, we propose a design for amorphous 2D and 3D PBG materials that is inspired by how cells pack in dense tissues in biology. We generate structures that exhibit broad PBGs based on a simple model that has been shown to describe cell shapes and tissue mechanical behavior. An advantage of this design is that the photonic and mechanical properties of the material are closely coupled. The material can also be tuned to undergo a density-independent solid–fluid transition, and the PBG persists well into the fluid phase. With recent advances in tunable self-assembly of nanoparticles or biomimetic emulsion droplets, this design can be used to create a "photonic fluid."
Model for Epithelial Cell Packing in 2D.
When epithelial and endothelial cells pack densely in 2D to form a confluent monolayer, the structure of the resulting tissue can be described by a polygonal tiling (18). A great variety of cell shape structures have been observed in tissue monolayers, ranging from near-regular tiling of cells that resembles a dry foam or honeycomb lattice (19) to highly irregular tilings of elongated cells (20). To better understand how cell shapes arise from cell-level interactions, a framework called the Self-Propelled Voronoi (SPV) model has been developed recently (21, 22). In the SPV model, the basic degrees of freedom are the set of 2D cell centers {ri}, and cell shapes are given by the resulting Voronoi tessellation. The complex biomechanics that govern intracellular and intercellular interactions can be coarse-grained (18, 19, 23⇓⇓⇓–27) and expressed in terms of a mechanical energy functional for individual cell shapes.E=∑i=1NKA(Ai−A0)2+KP(Pi−P0)2.[1]The SPV energy functional is quadratic in both cell areas ({Ai}) with modulus KA and cell perimeters ({Pi}) with modulus KP. The parameters A0 and P0 set the preferred values for area and perimeter, respectively. Changes to cell perimeters are directly related to the deformation of the acto-myosin cortex concentrated near the cell membrane. After expanding Eq. 1, the term KPPi2 corresponds to the elastic energy associated with deforming the cortex. The linear term in cell perimeter, −2KPP0Pi, represents the effective line tension in the cortex and gives rise to a "preferred perimeter" P0. The value of P0 can be decreased by up-regulating the contractile tension in the cortex (19, 24, 27), and it can be increased by up-regulating cell–cell adhesion. We simulate tissues containing N cells under periodic boundary conditions; the value of N has been varied from N=64 to 1600 to check for finite-size effects (SI Appendix, Fig. S6). A0 is set to be equal to the average area per cell, and A0 is used as the unit of length. After nondimensionalizing Eq. 1 by KAA02 as the unit energy scale, we choose KP/(KAA0)=1 such that the perimeter and area terms contribute equally to the cell shapes. The choice of KP does not affect the results presented. The preferred cell perimeter is rescaled p0=P0/A0 and varied between 3.7 (corresponding to the perimeter of a regular hexagon with unit area) and 4.6 (corresponding to the perimeter of an equilateral triangle with unit area) (27). We obtain disordered ground states of the SPV model by minimizing E, using the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm (28) starting from a random Poisson point pattern. We also test the finite temperature behavior of the SPV model by performing Brownian dynamics (21).
The ground states of Eq. 1 are amorphous tilings where the cells have approximately equal area but varying perimeters as dictated by the preferred cell perimeter p0. It has been shown that at a critical value of p0*≈3.81, the tissue collectively undergoes a solid–fluid transition (27). When p0<p0*, cells must overcome finite energy barriers to rearrange and the tissue behaves as a solid, while above p0*, the tissue becomes a fluid with a vanishing shear modulus as well as vanishing energy barriers for rearrangements (27). Coupled to these mechanical changes, there is a clear signature in cell shapes at the transition (21, 29, 30): The shape-based order parameter calculated by averaging the observed cell perimeter-to-area ratio s=⟨P/A⟩ grows linearly with p0 when p0>p0* in the fluid phase but remains at a constant (s≈p0*) in the solid phase. In Fig. 1A, we show three representative snapshots of the ground states at various values of p0. We take advantage of the diversity and tunability of the point patterns and cell structures (Fig. 1A) produced by the SPV model and use them as templates to engineer photonic materials.
Tissue structure in the SPV model. (A) Simulation snapshots at three different values of the preferred cell perimeters p0. Cell centers are indicated by points, and cell shapes are given by their Voronoi tessellation (red outlines). (B) Contour plot of the structure factor S(qx,qy) corresponding to the states shown in A. Scale bar has length 2π/D in reciprocal space, where D is the average spacing between cell centers. (C) Pair-correlation function g(r) at different values of p0. (D) Structure factor S(q) at different values of p0.
Characterization of 2D Structure.
To better understand the ground states of the SPV model, we first probe short-range order by analyzing the pair-correlation function g(r) (see details in Materials and Methods) of cell centers. In Fig. 1C, g(r) for the solid phase (p0<3.81) shows mutual exclusion between nearest neighbors and becomes constant at large distances. These features are similar to those observed in other amorphous materials with short-range repulsion and a lack of long-range positional order, such as jammed granular packings (31) and dense colloidal arrays (32). When p0 is increased, the tissue enters into the fluid phase at p0>3.81. To satisfy the higher preferred perimeters, cells must become more elongated. And when two neighboring elongated cells align locally, their centers can be near each other, whereas cells not aligned will have centers that are further apart. As a result, the first peak of g(r) broadens. Hence, as p0 is increased, short-range order is reduced. Deeper in the fluid regime, when p0>4.2, g(r) starts to develop a peak close to r=0, which means that cell centers can come arbitrarily close. Interestingly, the loss of short-range order does not coincide with the solid–fluid transition, which yields an intermediate fluid state that retains short-range order.
Next we focus on the structural order at long length scales. While the SPV ground states are aperiodic by construction, they show interesting long-range density correlations. The structure factor S(q) (see details in Materials and Methods) is plotted for various p0 values in Fig. 1 B and D. Strikingly, for all p0 values tested, the structure factor vanishes as q→0, corresponding to a persistent density correlation at long distances. This type of "hidden" long-range order is characteristic of patterns that are known as hyperuniformity (33, 34). In real space, hyperuniformity is equivalent to when the variance of the number of points σR2 in an observation window of radius R grows as function of the surface area of the window—that is, σR2∝Rd−1, where d is the space dimension (33). This is in contrast to the σR2∝Rd scaling that holds for uncorrelated random patterns. Indeed, real space measurements in the SPV model also confirm that the distribution of cell centers is strongly hyperuniform for all values of p0 and system sizes tested that include both solid and fluid states (SI Appendix, Fig. S1).
It has been suggested that hyperuniform amorphous patterns can be used to design photonic materials that yield PBGs (9, 10). Florescu et al. (9) further conjectured that hyperuniformity is necessary for the creation of PBGs. However, recent work by Froufe-Pérez et al. (14) have demonstrated that short-range order rather than hyperuniformity may be more important for PBGs. The SPV model provides a unique example of a hyperuniform point pattern with a short-range order that can be turned on and off. This tunability will allow a direct test of the ideas proposed in refs. 9, 10, and 14.
2D Photonic Material Design and Properties.
For any point pattern (crystalline or amorphous), the first step in the engineering of PBGs is to decorate it with a high dielectric contrast material. The simplest protocol is to place cylinders centered at each point {ri=(xi,yi)} that are infinitely tall in the z−direction. Such design typically yields bandgaps in the transverse magnetic (TM) polarization (the magnetic field is parallel to the xy-plane) (35). Based on this design, we first construct a material using SPV point patterns. To maximize the size of the bandgap, the cylinders are endowed with dielectric constant ϵ=11.56 and radius r/D=0.189 (14). We will refer to this construction as "TM-optimized." We also use a second decoration method (9, 14) that has been shown to yield complete PBGs—that is, gaps in both TM and Transverse Electric (TE) polarizations. We use a design based on the Delaunay triangulation of a point pattern. Cylinders with ϵ=11.56 and radius r/D=0.18 are placed at the nodes of the Delaunay triangulation while walls with ϵ=11.56 and thickness w/D=0.05 are placed on the bonds of this trivalent network. We refer to this construction as "TM + TE-optimized." Photonic properties are numerically calculated using the plane wave expansion method (36) implemented in the MIT Photonic Bands program. We use the supercell approximation in which a finite sample of N cells is repeated periodically. The photonic band structure is calculated by following the path of k∥=(0,0)→(12,12)→(−13,13)→(0,0) in reciprocal space. SI Appendix includes a sample script used for photonic band calculations.
The TM-optimized band structure based on a SPV ground state with N=64 cells and p0=3.85 is shown in Fig. 2A. Due to the aperiodic nature of the structure, the PBG is isotropic in k∥. We also calculate the ODOS (Fig. 2B) by binning eigenfrequencies from 10 samples with the same p0 but different initial seeds. The relative size of the PBG can be characterized by the gap–midgap ratio Δω/ω0, which is plotted as a function of p0 in Fig. 3A for both TM- and TM + TE-optimized structures. We find that the size of the PBG is constant in the solid phase of the SPV model (p0<p0*) with width Δω/ω0≈0.36 for the TM-optimized structure and Δω/ω0≈0.1 in the TM + TE-optimized structure. In the fluid phase, Δω/ω0 decreases as p0 increases yet stays finite in the range of 3.81<p0≲4.0. At even larger p0 values, the PBG vanishes. The location at which the PBG vanishes appears to coincide with the loss of short-range order in the structure. To quantify this, we plot Δω/ω0 versus the first peak height of the pair-correlation g1 in Fig. 3C. This is in agreement with the findings of Yang et al. (11) and suggests that short-range positional order is essential to obtaining a PBG that allows for collective Bragg backscattering of the dielectric material. This also shows that PBGs are absent in states that are hyperuniform but missing short-range order.
Characterizing photonic properties in 2D. (A) Photonic band structure of Transverse Magnetic (TM) for the material constructed by placing dielectric cylinders at the cell centers exhibits a PBG. Design is based on a ground state of the SPV at p0=3.85. k∥ is the in-plane wave vector. (B) The optical density of states (ODOS) of TM at different values of p0. The width of the bandgap Δω has a strong dependence on p0, while the midgap frequency ω0 remains constant (SI Appendix, Fig. S4).
Tunability of photonic properties in 2D. (A) The structure of the PBG as a function of p0. The TM-optimized structure corresponds to the size of the TM bandgap for a material constructed by placing dielectric cylinders at cell centers. The TM + TE-Optimized structure corresponds to complete PBGs for a material constructed using a trivalent network design. Phases are colored according to the mechanical property of the material. At p0≈3.81, the material undergoes a solid–fluid transition where the shear modulus vanishes. The dependence of ω0 on p0 is weak as shown in SI Appendix, Fig. S4A. (B) Effect of heating on the PBG in the TM-optimized structure. At fixed p0=3.7, temperature T is gradually increased. At T≈0.25, the material begins to fluidize through melting, while the bandgap still persists into the mechanical fluid phase. (C) The relationship between the bandgap size in the TM-optimized structure and the short-range order of the system. The explicit dependence of short-range order on p0 and T is shown in SI Appendix, Figs. S2 and S3.
To test for finite-size dependence of the ODOS and the PBG, we carry out the photonic band calculations at p0=3.7 for various system sizes ranging from N=64 to N=1600. At each system size, the ODOS was generated by tabulating TM frequencies along the k∥=(0,0) and k∥=(0.5,0.5) directions in reciprocal space for 10 randomly generated states. As shown in SI Appendix, Fig. S6, while low-frequency modes may depend on the system size and bigger fluctuations exist for smaller systems, the PBG is always located between mode numbers N and N+1 and has a width that does not change as a function of N.
Since the model behaves as a fluid-like state above p0*≈3.81 (21, 27) and the PBG does not vanish in the fluid-like regime (Fig. 3A), this gives rise to a photonic fluid where a PBG can exist without a static and rigid structure. To show this explicitly, we test the effects of fluid-like cell rearrangements by analyzing the photonic properties of the dynamical fluid phase at finite temperature. At a fixed value of p0=3.7, we simulate Brownian dynamics in the SPV model at different temperatures T. At each T, we take 10 steady-state samples and construct the TM-optimized structures to calculate their ODOS. In Fig. 3B, we plot the bandgap size as a function of increasing temperature. Note that even past the melting temperature of T≈0.25 (21), the PBG does not vanish, again giving rise to a robust photonic fluid phase. Inside the fluid phase, we also find that the PBG is not affected by the positional changes due to cell rearrangements (SI Appendix, Fig. S5). Finally, we analyze the effect of heating on the short-range order. In Fig. 3C, increasing T results in another "path" in manipulating the short-range order.
Extension to 3D Photonic Material.
To further demonstrate the viability and versatility of tissue-inspired structures as design templates for photonic materials, we extend this study to 3D. Recently, Merkel and Manning (37, 38) generalized the 2D SPV model to simulate cell shapes in 3D tissue aggregates by replacing the cell area and perimeter with the cell volume and surface area, respectively. This results in a quadratic energy functional that is a direct analog of Eq. 1:E=∑i=1NKS(Si−S0)2+KV(Vi−V0)2,[2]where Si and Vi are the surface area and volume of the i-th cell in 3D, with the preferred surface area and volume being S0 and V0, respectively. Similar to the 2D version of the model, we have two moduli—KS for the surface area and KV for volume. Following ref. 37, we make our model dimensionless by setting V01/3 as the unit of length and KSV04/3 as the unit of energy. This gives us a dimensionless energy and dimensionless shape factor s0=S0/V02/3 as the single tunable parameter in 3D, which is the anaolog of the parameter p0 in the 2D scenario. For the 3D model, we perform Monte Carlo simulations (39) with the cell centers at a scaled temperature T=1, expressed in the unit KSV04/3/kB where kB is the Boltzmann constant. During the simulation, each randomly chosen cell center is given by a displacement following the Metropolis algorithm (40), where the Boltzmann factor is calculated using the energy function in Eq. 2. For this purpose, we extract the cell surface areas and volumes from 3D Voronoi tessellations generated using the Voro++ library (41). N such moves constitute a Monte Carlo step, and we perform 105 such steps to ensure that the cells have reached a steady state. Then we run for another 105 steps to compute the g(r) and S(q). The average volume per cell is held constant for this procedure. Periodic boundary conditions were applied in all directions. For all of the simulations, we keep the scaled modulus KVV02/3/KS=1. It was previously found (37) that the T=0 ground states undergo a similar solid-to-fluid transition at s0∼5.4—that is, solid for s0<5.4 and fluid when s0≥5.4. Our Monte Carlo simulations also recover this transition near s0=5.4 when we plot an effective diffusivity, extracted from the mean-square displacement (MSD) of the cells, at different s0 values (SI Appendix, Fig. S9). States below the transition (s0=5) and above the transition (s0=5.82) are shown in Fig. 4 for a system of N=100 cells.
Structure characterization in the 3D Voronoi cell model. (A) Cell centers and their corresponding Voronoi tessellation as well as the decorated 3D photonic structure are shown for a state at s0=5 and N=100 cells. The cell centers are drawn with a finite size and different colors only to aid visualization. (B) Cell centers and their corresponding Voronoi tessellation as well as the decorated 3D photonic structure are shown for a state at s0=5.82 and N=100 cells. (C) Pair-correlation function g(r) at different values of s0. (D) Structure factor S(q) at different values of s0.
We characterize the structure of the 3D cell model by calculating their pair-correlation function g(r). In Fig. 4C, the short-range order behaves similar to the 2D case. At low values of s0 that correspond to rigid solids, the first peak in g(r) is pronounced, suggesting an effective repulsion between nearest neighbors. As s0 is increased, this short-range order gets eroded as a preference for larger surface area-to-volume ratio allows nearest neighbors to be close. The s0=6.1 state in Fig. 4C is an extreme example where it is possible for two cell centers to be arbitrarily near. However, the long-range order remains throughout all values of s0 tested as shown by the S(q) in Fig. 4D. The small value of S(q→0) is a consequence of suppressed density fluctuations across the system when cells all prefer the same volume dictated by Eq. 2. Whether they are truly hyperuniform would require sampling at higher system sizes, which is beyond the scope of this study.
Next, to make a photonic material, we decorate the Voronoi tessellations to create a connected dielectric network. While a Voronoi tessellation is already a connected network made of vertices and edges, it possesses a large dispersion of edge lengths. This can result in vertices that are arbitrarily close to each other and could hinder the creation of PBGs (42). To overcome this, we adopt a method described in refs. 9, 15, and 43 to make the structure locally more uniform. In a 3D Voronoi tessellation, each vertex is calculated from the circumcenter of the four neighboring cell centers and edges are formed by connecting adjacent vertices. In this design protocol, the connectivity of the dielectric network is the same as the network of the vertices and edges in the Voronoi tessellation. However, the vertex positions of the dielectric network are replaced by the center-of-mass (barycenters) of the four neighboring Voronoi cell centers. The resulting structure is a tetrahedrally connected network where the edges are more uniform in length, two representative samples are shown in Fig. 5A. Next we decorate the network with dielectric rods of width W running along the edges. For the dielectric rods, we again use ϵ=11.56, and their width W is chosen such that the volume filling fraction of the network is Vrod/Vbox=20% (42).
Characterizing photonic properties in the 3D design. (A) The optical density of states is shown at various values of s0. Here frequency is in units of 2πc/L, where L is the average edge length in the photonic network. (B) The size of the gap–midgap ratio Δω/ω0 as a function of s0. (C) Midgap frequency ω0 as a function of s0.
The photonic properties of the 3D dielectric network are calculated using the MIT Photonic Bands program (36). We calculate the ODOS for structures based on different values of s0. Here we have chosen structures containing N=100 cells. Due to the isotropic nature of the photonic band structure (SI Appendix, Fig. S7), we generate the ODOS based on two reciprocal vectors k=(0,0,0) & k=(0.5,0.5,0). At each value of s0, we average over 10 different random samples. We find the first complete PBG between mode number nV and nV+1, where nV is the number of vertices. In the solid phase of the model (s0<5.4), we find an average gap–midgap ratio of ∼6%; this decreases as s0 is increased and becomes vanishingly small when the model is in its fluid phase (s0>5.4) (Fig. 5B). Interestingly, the midgap frequency ω0 also shifts slightly toward lower values with increasing s0 (Fig. 5C). The appearance of the PBG here also coincides with the presence of short-range order. The PBG vanishes when there is no longer a pronounced first peak in the g(r).
Discussion and Conclusion
We have shown that structures inspired by how cells pack in dense tissues can be used as a template for designing amorphous materials with full PBGs. The most striking feature of this material is the simultaneous tunability of mechanical and photonic properties. The structures have a short-range order that can be tuned by a single parameter, which governs the ratio between cell surface area and cell volume (or perimeter-to-area ratio in 2D). The resulting material can be tuned to transition between a solid and a fluid state, and the PBG can be varied continuously. Remarkably, the PBG persists even when the material behaves as a fluid. Furthermore, we have explored different ways of tuning the short-range order in the material including cooling/heating and changing cell–cell interactions. We propose that the results in Fig. 3C can be used as a guide map for building a photonic switch that is either mechanosensitive (changing p0 or s0) or thermosensitive (cooling/heating).
While they are seemingly devoid of long-range order (i.e., they are always amorphous and nonperiodic), these tissue-inspired structures always exhibit strong hyperuniformity. Most interestingly, there are two classes of hyperuniform states found in this work: One that has short-range order, and one that does not. While the former is similar to hyperuniform structures studied previously, the latter class is new and exotic and has not been observed before. Furthermore, we have shown that hyperuniformity alone is not sufficient for obtaining PBGs, which complements recent studies (14). Rather, the presence of short-range order is crucial for a PBG. Another recent study has suggested that the local self-uniformity (LSU) (15)—a measure of the similarity in a network's internal structure—is crucial for bandgap formation. We believe that the states from the SPV model with short-range order also have a high degree of LSU, and it is likely that LSU is a more stringent criterion for PBG formation than the simplified measure of short-range order based on g(r). This will be a promising avenue for future work.
It will be straightforward to manufacture static photonic materials based on this design using 3D printing or laser etching techniques (10, 13, 15). In addition, top–down fabrication techniques such as electron beam lithography or focused ion beam milling can also be used that will precisely control the geometry and arrangement of micro/nanostructures.
An even more exciting possibility is to adapt this design protocol to self-assemble structures. Recent advances in emulsion droplets have demonstrated feasibility to reconfigure the droplet network via tunable interfacial tensions and bulk mechanical compression (44⇓–46). Tuning interfacial interactions such as tension and adhesion coincides closely with the tuning parameter in the cell-based model p0 (2D) and s0 (3D), which are inspired by the interplay of intracellular tension and cell–cell adhesion in a biological tissue. Experimentally this may lead to construction of a tunable range of artificial cellular materials that vary in surface area-to-volume ratios. Further the dynamically reconfigurable complex emulsions via tunable interfacial tensions (45) could lead to switching of these properties in real time. Another possibility is the creation of inverted structures or "inverse opals" by using the emulsion droplet network as a template (47, 48), which is often able to enhance the photonic properties over the original template. Alternatively, nanoparticles grafted with polymer brushes (49, 50) could be designed to tune the effective surface tension of individual particles as well as the adhesion strengths between particles. This could allow the mimicking of the interaction between cells and give rise to a controllable preferred cell perimeter in 2D.
Two recent open-source software packages, cellGPU (22) and AVM (51), have made it convenient to simulate very large system sizes in 2D. This would allow in-depth analysis of the system-size dependence of long- and short-range order in this model, which is an exciting possibility for future research.
Characterization of Structure.
The pair correlation function is defined as (52)g(r)=1Nρ∑i∑i≠jδ r→+ri→−rj→.ri→ is the position of the ith particle, N is the number of particles, and ρ is the average particle density of the isotropic system. 〈⋅〉 denotes n ensemble average over different random configurations at the same parameter set. The structure factor is given by (53)S(q→)=1N∑i,jeiq→⋅ri→−rj→.〈⋅〉 denotes n ensemble average over different random configurations at the same parameter set. S(q) is obtained by further averaging over a sphere of radius q in reciprocal space.
Photonic Band Structure Calculation.
Photonic properties are numerically calculated using the plane wave expansion method (36) implemented in the MIT Photonic Bands program. We use the supercell approximation in which a finite sample of N cells is repeated periodically. SI Appendix includes a sample script used for photonic band calculations in 2D.
The authors thank M. Lisa Manning, Bulbul Chakraborty, Abe Clark, Daniel Sussman, and Ran Ni for helpful discussions. The authors acknowledge the support of the Northeastern University Discovery Cluster and The Massachusetts Green High Performance Computing Center (MGHPCC).
↵1To whom correspondence should be addressed. Email: d.bi{at}northeastern.edu.
Author contributions: D.B. designed research; X.L., A.D., and D.B. performed research; X.L., A.D., and D.B. analyzed data; and X.L., A.D., and D.B. wrote the paper.
(1987) Strong localization of photons in certain disordered dielectric superlattices. Phys Rev Lett 58:2486–2489.
Yablonovitch E
(1987) Inhibited spontaneous emission in solid-state physics and electronics. Phys Rev Lett 58:2059–2062.
Cao H
(2005) Random lasers: Development, features and applications. Opt Photon News 16:24–29.
Chutinan A,
John S,
Toader O
(2003) Diffractionless flow of light in all-optical microchips. Phys Rev Lett 90:123901.
Noh H, et al.
(2011) Control of lasing in biomimetic structures with short-range order. Phys Rev Lett 106:183901.
Rechtsman M, et al.
(2011) Amorphous photonic lattices: Band gaps, effective mass, and suppressed transport. Phys Rev Lett 106:193904.
Wiersma DS
(2013) Disordered photonics. Nat Photon 7:188–196.
Shi L, et al.
(2013) Amorphous photonic crystals with only short-range order. Adv Mater 25:5314–5320.
Florescu M,
Torquato S,
Steinhardt PJ
(2009) Designer disordered materials with large, complete photonic band gaps. Proc Natl Acad Sci USA 106:20658–20663.
Man W, et al.
(2013) Isotropic band gaps and freeform waveguides observed in hyperuniform disordered photonic solids. Proc Natl Acad Sci USA 110:15886–15891.
Yang JK, et al.
(2010) Photonic-band-gap effects in two-dimensional polycrystalline and amorphous structures. Phys Rev A 82:053838.
Conley GM,
Burresi M,
Pratesi F,
Vynck K,
(2014) Light transport and localization in two-dimensional correlated disorder. Phys Rev Lett 112:143901.
Muller N,
Haberko J,
Marichy C,
Scheffold F
(2014) Silicon hyperuniform disordered photonic materials with a pronounced gap in the shortwave infrared. Adv Opt Mater 2:115–119.
Froufe-Pérez LS, et al.
(2016) Role of short-range order and hyperuniformity in the formation of band gaps in disordered photonic materials. Phys Rev Lett 117:053902.
Sellers SR,
Man W,
Sahba S,
Florescu M
(2017) Local self-uniformity in photonic networks. Nat Commun 8:14439.
Dufresne ER, et al.
(2009) Self-assembly of amorphous biophotonic nanostructures by phase separation. Soft Matter 5:1792–1795.
Dong BQ, et al.
(2011) Optical response of a disordered bicontinuous macroporous structure in the longhorn beetle Sphingnotus mirabilis. Phys Rev E 84:011915.
Nagai T,
Honda H
(2001) A dynamic cell model for the formation of epithelial tissues. Philos Mag B 81:699–719.
Farhadifar R,
Roeper JC,
Aigouy B,
Eaton S,
Julicher F
(2007) The influence of cell mechanics, cell-cell interactions, and proliferation on epithelial packing. Curr Biol 17:2095–2104.
Duclos G,
Garcia S,
Yevick HG,
Silberzan P
(2014) Perfect nematic order in confined monolayers of spindle-shaped cells. Soft Matter 10:2346–2353.
Bi D,
Yang X,
Marchetti MC,
Manning ML
(2016) Motility-driven glass and jamming transitions in biological tissues. Phys Rev X 6:021011.
Sussman DM
(2017) cellgpu: Massively parallel simulations of dynamic vertex models. Comput Phys Commun 219:400–406.
Hufnagel L,
Teleman AA,
Rouault H,
Cohen SM,
Shraiman BI
(2007) On the mechanism of wing size determination in fly development. Proc Natl Acad Sci USA 104:3835–3840.
Staple DB, et al.
(2010) Mechanics and remodelling of cell packings in epithelia. Eur Phys J E 33:117–127.
Fletcher AG,
Osterfield M,
Baker RE,
Shvartsman SY
(2014) Vertex models of epithelial morphogenesis. Biophys J 106:2291–2304.
Lopez JH,
Schwarz JM,
(2014) Energy barriers and cell migration in densely packed tissues. Soft Matter 10:1885–1890.
(2015) A density-independent rigidity transition in biological tissues. Nat Phys 11:1074–1079.
Byrd RH,
Lu P,
Nocedal J,
Zhu C
(1995) A limited memory algorithm for bound constrained optimization. SIAM J Sci Comput 16:1190–1208.
Park JA, et al.
(2015) Unjamming and cell shape in the asthmatic airway epithelium. Nat Mater 14:1040–1048.
Atia L, et al.
(2018) Geometric constraints during epithelial jamming. Nat Phys doi:10.1038/s41567-018-0089-9.
O'Hern CS,
Silbert LE,
Liu AJ,
Nagel SR
(2003) Jamming at zero temperature and zero applied stress: The epitome of disorder. Phys Rev E 68:011306.
Kegel WK,
van Blaaderen A
(2000) Direct observation of dynamical heterogeneities in colloidal hard-sphere suspensions. Science 287:290–293.
Stillinger FH
(2003) Local density fluctuations, hyperuniformity, and order metrics. Phys Rev E 68:041113.
Zachary CE,
Torquato S
(2009) Hyperuniformity in point patterns and two-phase random heterogeneous media. J Stat Mech Theory Exp 2009:P12015.
Joannopoulos JD,
Johnson SG,
Winn JN,
Meade RD
(2011) Photonic Crystals: Molding the Flow of Light (Princeton Univ Press, Princeton).
Joannopoulos JD
(2001) Block-iterative frequency-domain methods for Maxwell's equations in a planewave basis. Opt Express 8:173–190.
Merkel M,
(2018) A geometrically controlled rigidity transition in a model for confluent 3D tissues. New J Phys 20:022002.
Sharp TA,
Manning ML,
Liu AJ
(2018) Statistical properties of 3D cell geometry from 2D slices. arXiv:1802.09131.
Landau D,
Binder K
(2014) A Guide to Monte Carlo Simulations in Statistical Physics (Cambridge Univ Press, Cambridge, UK).
Allen MP,
Tildesley DJ
(1989) Computer Simulation of Liquids (Clarendon Press, New York).
Rycroft CH
(2009) Voro++: A three-dimensional Voronoi cell library in c++. Chaos 19:041111.
Liew SF, et al.
(2011) Photonic band gaps in three-dimensional network structures with short-range order. Phys Rev A 84:063818.
Sigmund O,
Hougaard K
(2008) Geometric properties of optimal photonic crystals. Phys Rev Lett 100:153904.
Pontani LL,
Jorjadze I,
Viasnoff V,
Brujic J
(2012) Biomimetic emulsions reveal the effect of mechanical forces on cell–cell adhesion. Proc Natl Acad Sci USA 109:9839–9844.
Zarzar LD, et al.
(2015) Dynamically reconfigurable complex emulsions via tunable interfacial tensions. Nature 518:520–524.
(2016) Cis and trans cooperativity of e-cadherin mediates adhesion in biomimetic lipid droplets. Biophys J 110:391–399.
Imhof A,
Pine DJ
(1997) Ordered macroporous materials by emulsion templating. Nature 389:948–951.
Manoharan VN,
Thorne JD,
(2001) Photonic crystals from emulsion templates. Adv Mater 13:447–450.
Kumar SK,
Jouault N,
Benicewicz B,
Neely T
(2013) Nanocomposites with polymer grafted nanoparticles. Macromolecules 46:3199–3214.
Rogers WB,
Shih WM,
Manoharan VN
(2016) Using DNA to program the self-assembly of colloidal nanoparticles and microparticles. Nat Rev Mater 1:16008.
Barton DL,
Henkes S,
Weijer CJ,
Sknepnek R
(2017) Active vertex model for cell-resolution description of epithelial tissue mechanics. PLOS Comput Biol 13:1–34.
Hansen JP,
McDonald IR
(2013) Chapter 2-statistical mechanics. Theory of Simple Liquids, eds Hansen JP, McDonald IR (Academic, Oxford), 4th Ed, pp 13–59.
(2013) Chapter 4-distribution function theories. Theory of Simple Liquids, eds Hansen JP, McDonald IR (Academic, Oxford), 4th Ed, pp 105–147.
You are going to email the following Biological tissue-inspired tunable photonic fluid
Xinzhi Li, Amit Das, Dapeng Bi
Proceedings of the National Academy of Sciences Jun 2018, 115 (26) 6650-6655; DOI: 10.1073/pnas.1715810115


What a beautiful mind you have.
High resolution wiring diagram of a brain.
I'm sorry. All I see is a mohawk.
The brain appears to be wired more like the checkerboard streets of New York City than the curvy lanes of Columbia, Md., suggests a new brain imaging study.
Hey, I'm from Columbia, have to wonder how many people understand this reference. In high school I made an entire street map of Columbia, by hand, and at one time knew almost every street by name like a London taxi, due to the map, and work in the pizza business. Anyway, Columbia does sort of look like the twisted folds of a brain with fractal properties. It also is where a lot of people who work at the NSA and NASA and other brainy places call home.
Yeah, yeah. All very noble. I'm guessin' that had they peered into my skull with their machine thingy, they'd now be describing the brain's structure as being more like sink-holes in a swamp.
I heard this on NPR today and while this is exciting it, I suspect, as usual, it loses a large bit of its nuance when it gets to the popular press.
We have already been mapping the brain for some time and we have pretty clear images that the individual neurons are shaped more like trees and this is the first I have heard about perpendicular 2-d connections and the finding seems to be quite a simplification.
Here are some more relevant links.
Eyewire, crowd sourced neuron mapping, You can help!
So this brain map is only showing 25% of what's there? Even knowing that there's a lot more than they show, the brain's wiring is way, way less dense and complicated than I would have guessed.
Other researchers describe the brain topography as more like the "Iggy-Pop-beef-jerky-sinews" of the streets of the West Village.
A neanderthal interviewed was like, "well, duh."
Boy, they sure hit the mark when they said "grid like New York"! I don't know many places where parallel streets cross each other, but surely in a city where 4th and 10th streets cross, that'll work.
"Of course. A child could do it."
Well, that's another strong argument AGAINST Intelligent Design.
All fixed, that's be thirty bucks, come right back if ya don't think it's fixed right.
This is very cool. Diffusion Tensor Imaging (DTI), which is the precursor to this, is pretty standard in MRI labs and happens to be what I work on at the moment. With a few click of my mouse I can see the white matter tracts that connect the different parts of the brain to each other and to the spinal cord. It kind of blows my mind.
DTI is cool but it's resolution limited. An MRI scan will have resolution on the order of 1mm x 1mm x 1mm (a box called a "voxel") and if you have tracts crossing inside a voxel you'll just get noise. Since brain circuitry is obviously below the 1mm^3 scale, DTI tractography lets us see the freeways in the brain, but not the side streets.
I'm new to the field and haven't read this paper yet, but it looks like DSI (Diffusion Spectrum Imaging) has somehow managed to break through that resolution barrier and show these really cool pictures. I'm impressed.
To put it very simply, the magnetic field in an MRI lines up the spins of the protons in your brain. A radio frequency field is applied which flips the spins to the opposite direction. When the RF stops the protons will switch back to being inline with the magnetic field and each proton releases energy as it does this. The released energy is what is seen by the MRI machine and reconstructed into a picture of your brain.
But that's just a simple scan that will map out brain anatomy and such. We can actually be a bit more clever. When we're lining up the spins of the protons in the magnetic field, we can create a magnetic field gradient. This means that the magnetic field is not the same at every point in space. The direction of the spin of each proton in the brain will therefore depend on its position in the detector -- we've location tagged every proton. But we then apply the reverse of the gradient to line everything back up in the same direction.
Now, for a static brain this gradient/anti-gradient wouldn't matter. Everything would be back and lined up how it started. But. If there is diffusion in your sample (ie water molecules randomly moving with respect to each other) you'll get protons which were aligned in one direction mixed up protons which were aligned in another direction. When the anti-gradient is applied, if a proton isn't in the same position it was when the gradient was applied it will be out of phase with nearby protons. If two nearby protons are out of phase with each other they will destructively interfere when they release their energy, leading to signal loss in areas with lots of diffusion. HUGE swaths of physics have been glossed over. Apologies to any medical physicists in the house.
Now. Nerve fibers are long and thin. This mean that water in and around the nerve fiber is going to tend to diffuse longitudinally as opposed to transversely. Say you set your gradient in the x direction, and you observe signal loss at point A. You just discovered that at point A water tends to diffuse along the x direction. If you then set the gradient along the y direction and don't observe the same signal loss at point A, you discovered that at that point water prefers to diffuse along the x direction. If you see a series of points where water prefers to diffuse in the same direction, you just discovered a tract -- a bundle of neurons connecting one part of the brain to another. You need to take gradients in at least 6 different directions to get the full 3D picture of the direction and strength of diffusion in each voxel.
"Tractography" is what these guy are doing (and doing very well) -- mapping out the tracts in the brain. But we can use this information for various interesting things. One of the things I look for is the degree of anisotropy in different parts of the brain. I don't care about where the tracts are going, just the degree to which one direction is preferred over the other directions. In a healthy brain you get high anisotropy -- lots of long fibers mean lots of strongly preferred directions. But if you've had a brain injury or potentially a condition like MS or ALS, you might lose some of those tracts and we see that by observing a lower anisotropy than in a healthy brain. So this stuff isn't just for pretty pictures -- it's very helpful in diagnostics as well.
I hope someone can chime in about how this new technique works in more detail.
Amazing. It was clear that there were going to be some discoveries in this field, but I think a regular grid is about the last thing anyone could have predicted.
This explains how my brain is a sieve, and the uniformly large sizes required to be enmeshed in there.
Yah, this is pretty damn cool. I'm not in imaging myself, so I can't really evaluate how much of this is flash vs substance, but this strikes me as a pretty big result.
Just to put this in context (although I am not neuroanatomist!), neuroscientists generally break the brain down into grey and white matter, where gray matter is primarily cell bodies (think processors) and white matter is primarily axons (think connectors/communicators). Now if we just focus on the cortex (the part that we generally associate with intelligence as opposed to low level motor control and hormones, etc) Gray matter actually has a surprisingly simple structure. The processing part of your brain exists essentially as a sheet covering your brain, six neuron layers think everywhere*. Yes, it's basically a simple 2d structure.
Now when non adjacent parts of your brain want to get talking, they throw out these long axons which go through the brain to connection to just about anywhere. Since the shortest path between two points is a straight line, we might expect that the axons would all just b line it to whatever region, which would result in the white matter of your brain being an incomprehensible tangle.
But it turns out it's not. The nerves (bundles of axons) which extend between different parts of your brain seem to always cross orthogonally - at right angles. This is a very interesting finding. At the end of the Science paper they speculate about reasons - simplifying axon path finding, helping to regularize timing issues - but this is an imaging paper, not a theoretical one. They've found a structure which is really cool, and now it's open to speculate about why it's so. It's what science is all about really.
* And of course actually connections are really just thrown out to anywhere. A lot of neuroscientists are using graph theory to find various relays and hubs in the structure of the brain. I think these days if you study neuroscience you'll still tend to get a big mess of biology thrown out you, but at the moment big strides are being made in breaking down the functional architecture of the brain. In twenty years introduction to neuroscience may involve as much graph theory as biology, and that's so awesome. But that's also me with my A.I. hat on, so don't place any bets on that claim.
I used to be a proponent of DTI. But now, when people post to Ask MetaFilter asking for help with their brain structure relationship issues, I think I'm just going to respond: DSIA.
- Six layers think = six layers thick.
- Asterisk should have been at the beginning of the next paragraph.
- Asterisk point at the end should be, connections *aren't* really thrown out anywhere.
Neural pathways that get used a lot tend to get built up more.
Neural pathways that provide access to many other neural pathways have a better chance of getting used more.
Neural pathways that cross many other neural pathways are better able to provide access thereof.
It makes intuitive sense, really. If nobody guessed it, it's because biology is generally counterintuitive.
And this is your brain on 'shrooms. Any questions?
I'm just surprised this hasn't been found out before. Is there a reason this kind of structure can't be seen if you examine a brain under a regular microscope?
I'm just surprised this hasn't been found out before.
i) There are references in the article to people suspecting that this may be the case, but this is the first result which demonstrates it on this scale.
ii) The nerves can stretch from end to end in the brain. They're fine, but long.
iii) Invasive techniques (e.g. Microscopy based) won't get you this big picture, because either you're looking through a hole in the head into a very local region, or your looking at some brain slice. And if you think about it, the chances of a 2d brain slice capturing a 2d grid structure are very small. Especially since these grids aren't necessarily flat.
iv) This is an extremely fine structure. Traditional MRI techniques have a resolution of 1mm cubed, which isn't sufficient to see anything but the largest pathways. You certainly couldn't resolve these orthogonal sheets.
Therefore, this observation had to wait for high resolution non invasive techniques. Which is what they used.
Thanks, no regrets, coyote, for the primer on DTI. If I understand correctly, the trick with DSI is that diffusion tensors are related via a Fourier transform to fiber orientation. There is apparently an additional shortcut to take with so-called q-ball imaging.
I'd also like to point out that Wedeen is a leading researcher in diffusion imaging techniques, but he is only one of several. The area is quite young, and many questions in tractography (which is what's shown here) are very contentious. Objects like the fiber-crossings he discusses are difficult to image and data from them is highly ambiguous. Although the patterns Wedeen has found are an interesting finding, they are still unconfirmed. Although the graphic you're seeing in the linked article looks very concrete and easy to grasp, it started with very abstract data that are difficult to visualize.
"The grid structure encodes dualities to model paradoxes, which are central to a task-driven system. These dualities are the atoms of memes.
Employing triangular numbers highlights how individual paradox units cooperate in a harmonic way, as birds form a functional flock gestalt."
I'd suspect some astroturfing bot but there's no spammy link so what's the point of throwing in a totally nonsensical statement?
I don't know many places where parallel streets cross each other, but surely in a city where 4th and 10th streets cross, that'll work.
In San Francisco, 16th St. crosses 7th St.; and 3rd St. runs parallel to 4th, but crosses 20th-26th Sts. It's still a grid.
In any city where the grid is deformed by trying to make it follow a natural feature like the shore or bank of a body of water, you'll get anomalies. You don't even want to know about New Orleans.
This reminds me of the simultaneous elation and deflation that accompanied the sequencing of the human genome: it too was vastly smaller and less complex than thought, which was interesting, but it meant that people had to stop thinking of themselves as their genes. So, too, there are all kinds of hints that people have been identifying far too much with their brains.


text:
Challand-Saint-Anselme (arpità Tchallàn) és un municipi italià, situat a la regió de Vall d'Aosta. L'any 2007 tenia 710 habitants. Limita amb els municipis de Brusson, Challand-Saint-Victor, Emarèse i Issime.

Demografia

Administració

Municipis de la Vall d'Aosta

redpajama_set_name: RedPajamaWikipedia


Revamp your casual layering line-up with this zip-through hoody from Superdry. Showcasing a grey hue, it's made from a cotton blend in a relaxed fit. Featuring long sleeves, side slash pockets and a generous hood, it's completed with a zip-through fastening and a branded detail across the chest. Ideal for off-duty days, it will look great styled with denim and trainers.


text:
Focal Illusion (2019), Courtesy of the artist and the Al Burda Endowment
b. 1975, Sharjah; lives between Abu Dhabi and Washington, D.C.
Ebtisam Abdulaziz is a multidisciplinary artist and writer. With a BA in Math and Science, Abdulaziz incorporates her unique perspective on mathematics and the structures of systems to explore issues of identity and culture through installations, performance pieces, video, paintings, and works on paper. Abdulaziz has been widely exhibited in the UAE and internationally. She was among the featured artists in the inaugural UAE and ADACH Pavilions at the 53rd Venice Biennale, as well as at the 7th and 10th Sharjah Biennials. She has shown at the Institut du Monde Arabe, Paris; the Kunst Museum, Bonn, Germany; FotoFest Biennial, Art in Houston, Texas; and The Florida Museum of Photographic Arts, Tampa, Florida, among other museums.


text:
Q: How to clone bootstrap multi-select dynamically?

$(function() {
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    includeSelectAllOption: true
  });

  $('#btnSelected').click(function() {
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<link href="http://netdna.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" rel="stylesheet" type="text/css" />
<link href="http://cdn.rawgit.com/davidstutz/bootstrap-multiselect/master/dist/css/bootstrap-multiselect.css" rel="stylesheet" type="text/css" />

<select id="days" multiple="multiple">
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<button type="button" id="btn">+ Add Another Set OF Hourse
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I am trying to do something like that when I click on add more button, multi-select drop-down will be cloned. And whenever, I click on submit it will show me selected values of all the multi-select(s).

A: I have added functionality to clone multi-select on clicking the add button. Moreover, I have modified selection method to get selected values from all the multi-select drop-down.

$('#days').multiselect({
  includeSelectAllOption: true
});

var i = 1;
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});

$('#btnGetSelected').click(function() {
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    var selected_option_selector = '#' + id + ' option:selected';
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    $(selected_option_selector).each(function(){
      result_str += $(this).text() + ' - ' + $(this).val() + ', ';
    });

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    result_str += '
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    $('.results').append(result_str);
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});
.results {
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}
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<link href="http://cdn.rawgit.com/davidstutz/bootstrap-multiselect/master/dist/css/bootstrap-multiselect.css" rel="stylesheet" type="text/css" />

    <select id="days" class="multiselect" multiple="multiple">
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      <option value="5">friday</option>
    </select>

<button id="btnGetSelected" class="btn btn-primary">Get Selected</button>
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Fiddle DEMO


We've already told you about the celebs filing into town for TIFF and the extended-licence nightspots they'll be frequenting. But with more than 300 movies being screened, the actual "film" part of the festival can be hard to navigate. Enter our handy guide, in which we scope out the buzz on the most hotly anticipated flicks of the fest.
This info is of little use towards the end of the festival.
Films from emerging countries need a bit more editing.