Everything We Know About Penitentes, Aka Ice Spikes
Just when you think nature can't surprise you anymore, it still manages to find a way to do so.
Up in the tall peaks of the Andes Mountains are fascinating formations standing watch over everything. These look like blades of snow jutting up from the ground as if reaching toward the sun or waiting for someone to roll down and cut them accidentally. Researchers called them penitentes, or nieves penitentes, after the Spanish word for penitents during Holy Week.
Charles Darwin first described these beautiful and somewhat shocking figures on the tops of mountains in the 1800s, Newsweek reported.
According to Amusing Planet, Darwin journeyed from Santiago, Chile, to the Argentine city of Mendoza in March 1835. To get there, he squeezed through the Andes and found fields covered with penitentes near the Piuquenes Pass. At the time, he said the ice was probably formed by strong winds rolling through the mountains, based on local beliefs.
Penitentes do look like blades. They often grow in clusters, with some only a few inches tall but others growing as high as 16 feet. Sometimes they cover entire snowfields, but they can also be found in patches. Yet, they're always reaching for the sun.
For several years, penitentes remained a mystery. The formations were only observed in hard-to-reach regions. These areas are cold, dry, windy, and not very conducive to sustaining life. It was too hard to conduct a close study of the natural phenomenon.
It's all thanks to sublimation
However, scientists are never people who just give up, so they've managed to trek up to the high reaches of the Andes to study the stunning formations.
Newsweek reported that researchers hiked up to the Volcan Llullaillaco to observe the penitentes. One scientist said they made sure their trucks had tons of water, so no one became dehydrated, which is why it was hard to study them in the first place.
A paper from the Journal of Glaciology noted penitentes do form in areas outside the Andes. Small ice spikes have also been found along Route 66 in Missouri, especially after heavy snowfall followed by dry, windy days. Although, the conditions are perfect in the Andes to grow the most outstanding examples of penitentes.
It turns out penitentes are formed thanks to a bunch of natural processes. One is sublimation, or when a solid turns to gas without becoming a liquid, kind of like dry ice. Per Amusing Planet, snowfields are not perfectly flat. Some areas concentrate sunlight and sublimate faster than others and leaves behind the snow surrounding it as spikes. The Journal of Glaciology added that the penitentes continue to grow and point to a cycle of evaporation and redeposition on the blades.
Penitentes grow bigger if snow or the ground can trap higher amounts of radiation or sunlight, possibly why the Andes produce the most impressive examples.
So while there is a possible theory to how ice spikes form, researchers want to know more.
Ice spikes may hold the key to alien life
One observation people saw while studying penitentes is that it could offer a way to save the glaciers. ScienceDaily wrote researchers sprinkled some carbon on lab-grown penitentes and found it affected the melting process. Since penitentes disappear slower, this method could help save the melting glaciers. But, other academics argue that the presence of carbon might be the very reason why penitentes absorb sunlight in the first place.
That's not the only possible way penitentes are intriguing to scientists. Newsweek said researchers in the Andes found evidence penitentes had red ice patches, a sign that some form of microscopic life exists within the ice. Studies showed the ice contained snow algae and proved penitentes offer shelter and water to life in an otherwise harsh environment. This discovery not only reveals how life survives dangerous places, but also provides an excellent starting point to find life on other planets.
NBC said NASA satellites found evidence that Jupiter's ocean moon Europa had clusters of spiky ice below its frozen ocean. Europa, despite having an ocean, is very dry and cold, perfect conditions to create penitentes. And if penitentes on Earth can hold life, maybe the ones on Europa do as well.
So next time you want to be surprised at Mother Nature, maybe consider a trip to the Andes.


Documenting the American South Logo
Eastern North Carolina Insane Asylum (Goldsboro, N.C.)
Goldsboro, N.C.: The Asylum, 1885.
The 1884 Superintendent's Report of the Eastern North Carolina Insane Asylum, written by Dr. J. D. Roberts for the asylum's board of directors and Governor Thomas J. Jarvis, provides updates on finances, repairs, and patient statistics. The asylum, now Cherry Hospital, was established in 1877 by the North Carolina General Assembly and opened in 1880 as the Asylum for Colored Insane, the state's only hospital for mentally ill African Americans. In the report, Dr. Roberts discusses various patient issues, including population movements, cures, and deaths, and cites an increase in insanity that caused the institution to reach a record high of 152 patients in 1884. He mentions the institution's needs, primarily building repairs, a new entrance, population management, and more female employees, and recommends the state allocate additional resources to meet the African American community's mental health needs. The superintendent also raises concerns about patient escapes, fire safety, and the proposed superintendent's residence, which he believes to be too small and too near the asylum. Roberts appends several tables that contain patient data, such as causes for admission, prior employment, and age. The work concludes with the treasurer's report.
Monique Prince
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Theopolis Podcast: Q&A Session (Historicity of the Exodus, Icons, Sacramental Administration, Fulfilled Prophecy)
Peter Leithart, James Bejon, Jeff Meyers, and I answer four questions from listeners: 1. Can we believe in the Exodus as an historical event? 2. How should we think about icons? 3. What are the boundaries of sacramental administration? 4. How should we discuss the fulfilment of prophecy with observant Jews?


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Cesar Chavez's home is designated national historic site
Cesar Chavez's California retreat has been added to the National Register of Historic Places.
Interior Secretary Ken Salazar announced the designation of the site in the Tehachapi Mountains where the labor leader lived and led the farm workers movement the last 22 years of his life.
Salazar, who called Chavez "one of the heroes of the 20th century,'' made the announcement at a gathering of the Congressional Hispanic Caucus Institute in Washington on Wednesday night.
The 187-acre Nuestra Senora Reina de La Paz in Keene, southeast of Bakersfield, served as headquarters of the United Farm Workers and Chavez's residence from 1971 to 1993. It is now home to the National Chavez Center. Chavez was buried there in 1993.
The listing is largely honorific. The site is one of a number of places in the West associated with Chavez's life that are under consideration for designation as national historic landmarks or additions to the national park system. The National Park Service staff is expected to send its recommendations to Congress early next year.
"For my father, La Paz was a personal refuge from bitter struggles in agricultural valleys and big cities, a spiritual harbor where he recharged batteries, drew fresh inspiration and prepared for the battles ahead," Paul F. Chavez, Cesar Chavez's middle son and president of the Cesar Chavez Foundation, said in a statement. "It was a place where many dedicated people spent years of their lives working with Cesar Chavez for social justice, inspiring generations of Americans from all walks of life who never worked on a farm to social and political activism."
The National Register of Historic Places includes more than 87,000 historic buildings, structures, districts, sites and objects. La Paz was nominated for listing by California's state historic preservation officer. A 12-member advisory board then recommended the designation to Salazar, who approved it after visiting the site.
As the leader of the United Farm Workers union, Chavez staged a massive grape boycott that raised awareness of the plight of predominantly Latino farmworkers. His efforts were credited with inspiring millions of other Latinos in their fight for more educational opportunities, better housing and more political power.
--Richard Simon reporting from Washington, D.C.
Photo: Villa La Paz, a conference and education center, is located at the National Chavez Center at La Paz in Keene, Ca. The site has been added to the National Register of Historic Places. Credit: Mel Melcon/Los Angeles Times

source: HuggingFaceFW/fineweb-edu


From Wikipedia, the free encyclopedia
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Liquorice candies in different colours in Jyväskylä, Finland
M&Ms, chocolate with a colored sugar shell.
Confectionery is related to food items that are rich in sugar and often referred to as a confection. Confectionery refers to the art of creating sugar based dessert forms, or subtleties (subtlety or sotelty), often with pastillage. From the Old French confection, origin of Latin confectio(n-), from conficere, to "put together".[1][2] The confectionery industry also includes specialized training schools and extensive historical records.[3] Traditional confectionery goes back to ancient times, and continued to be eaten through the Middle Ages into the modern era. Confections include sweet foods, sweetmeats, digestive aids that are sweet, elaborate creations, and something amusing and frivolous.[4]
Modern usage may include substances rich in artificial sweeteners as well. The words candy (US and Canada), sweets (UK and Ireland), and lollies (Australia and New Zealand) are also used for the extensive variety of confectionery.
Generally, confections are low in micronutrients but rich in calories. Specially formulated chocolate has been manufactured in the past for military use as a high density food energy source.
Sweetening agents[edit]
Confectioneries are defined by the presence of sweeteners. These are usually sugars, but it is possible to buy sugar-free sweets, such as sugar-free peppermints. Most common is the disaccharide sucrose. Hydrolysis of sucrose gives a mixture called invert sugar, which is sweeter and is also a common ingredient. Finally confectioneries, especially commercial ones, are sweetened by a variety of syrups obtained by hydrolysis of starch, these include corn syrup.[5]
Regional names[edit]
Different dialects of English use regional terms for confections:
 - In Britain, Ireland and some Commonwealth countries, sweets or, more colloquially, sweeties (particularly used by children, the Scottish Gaelic word suiteis is a derivative). In some parts of England, spice, joy joy and goodies are terms used, alongside sweets, to denote confectionery. In North West England, especially Lancashire, toffees is often used as a generic term for all confectionery. Northeast England and the Scottish Borders commonly use the words chuggy, chuddy and chowie, as localised terms for chewing gum. In North East England, the word kets is commonly used for confectionery.
 - In Australia and New Zealand, lollies.
 - In North America, candy, although this term generally refers to a specific range of confectionery and does not include some items called confectionery (e.g. ice cream). Sweet is occasionally used, as well as treat.
Rock candy is simply sugar with colouring or flavor added.
Peeps are one of many types of marshmallow-type candies.
Brittles are a combination of nuts and caramelized sugar.
Chocolate is a common and popular confectionery and can be used in a wide variety of ways.
Confectionery items include sweets, lollipops, candy bars, chocolate, cotton candy, and other sweet items of snack food. The term does not generally apply to cakes, biscuits, or puddings which require cutlery to consume, although exceptions such as petits fours or meringues exist.[citation needed]
Some of the categories and types of confectionery include the following:[5]
 - Caramels: Derived from a mixture of sucrose, glucose syrup, and milk products. The mixture does not crystallize, thus remains tacky.
 - Chocolates: Bite-sized confectioneries generally made with chocolate.
 - Divinity: A nougat-like confectionery based on egg whites with chopped nuts.
 - Dodol: A toffee-like food delicacy popular in Indonesia, Malaysia, and the Philippines
 - Dragée: Sugar-coated almonds and other types of sugar panned candy.
 - Fondant: Prepared from a warm mixture of glucose syrup and sucrose, which is partially crystallized. The fineness of the crystallites results in a creamy texture.
 - Fudge: Made by boiling milk and sugar to the soft-ball stage. In the US, it tends to be chocolate-flavored.
 - Halvah: Confectionery based on tahini, a paste made from ground sesame seeds.
 - Hard sweets: Based on sugars cooked to the hard-crack stage. Examples include suckers (known as boiled sweets in British English), lollipops, jawbreakers (or gobstoppers), lemon drops, peppermint drops and disks, candy canes, rock candy, etc. Also included are types often mixed with nuts such as brittle. Others contain flavorings including coffee such as Kopiko.
 - Ice cream: Frozen, flavoured cream, often containing small pieces of chocolate, fruits and/or nuts.
 - Jelly candies: Including those based on sugar and starch, pectin, gum, or gelatin such as Turkish delight (lokum), jelly beans, gumdrops, jujubes, gummies, etc. [6]
 - Liquorice: Containing extract of the liquorice root. Chewier and more resilient than gum/gelatin candies, but still designed for swallowing. For example, Liquorice allsorts. Has a similar taste to star anise.
 - Marshmallow: "Peeps" (a trade name), circus peanuts, fluffy puff, Jet-Puffed Marshmallows etc.
 - Marzipan: An almond-based confection, doughy in consistency, served in several different ways.
 - Mithai: A generic term for confectionery in India, typically made from dairy products and/or some form of flour. Sugar or molases are used as sweeteners.
 - Tablet: A crumbly milk-based soft and hard candy, based on sugars cooked to the soft-ball stage. Comes in several forms, such as wafers and heart shapes. Not to be confused with tableting, a method of candy production.
 - Taffy or chews: A candy that is folded many times above 50 °C, incorporating air bubbles thus reducing its density and making it opaque.
Excessive consumption of confectionery has been associated with increased incidences of type 2 diabetes, obesity, and tooth decay.[7]
Contaminants and coloring agents as well as toys and other non-nutritive products in confectionery can be particularly harmful to children. This non-nutritive material can cause injury or pose choking hazards. Therefore, confectionery contaminants such as high levels of lead have been restricted to 1 ppm in the US. There is no specific maximum in the EU.[8]
Candy colorants, particularly yellow colorants such as E102 Tartrazine, E104 Quinoline Yellow and E110 Sunset Yellow FCF, do have many restrictions around the world. Tartrazine, for example, can cause allergic and asthmatic reactions and was once banned in Austria, Germany, and Norway. Some countries such as the UK have asked the food industry to phase out the use of these colorants, especially for products marketed to children.[9]
Non-nutritive toy products such as chocolate eggs containing packaging with a toy inside are banned from sale in the US. If the material attached to confectionery does have a function and will not cause any injury to the consumer, it is allowed to be marketed. In the EU however, the Toy Safety Directive 2009/48/EC specifies that toys contained in food only need separate packaging that cannot be swallowed.[10]
See also[edit]
 1. ^ confection: definition of confection in Oxford dictionary (British & World English). (2014-02-12). Retrieved on 2014-02-16.
 2. ^ Confectionery - Definition and More from the Free Merriam-Webster Dictionary. (2012-08-31). Retrieved on 2014-02-16.
 3. ^
 4. ^ Confection | Define Confection at Retrieved on 2014-02-16.
 5. ^ a b Terry Richardson, Geert Andersen, "Confectionery" in Ullmann's Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. doi:10.1002/_PHONE_.a07 411
 6. ^ Margaret McWilliams. (2006) Nutrition and Dietetics Eighth edition edn. Prentice Hall: Pearson Education Inc.
 7. ^ Magee, Elaine; "Sugar: What Kinds to Eat and When" (Health & Cooking), 28 January 2009 (Retrieved: 11 July 2009)
 8. ^ EFSA Scientific Opinion on Lead in Food European Food Safety Authority (EFSA), Retrieved 11/13/2012
 9. ^ Ministers agree food Color ban BBC News, Retrieved 11/14/2012
 10. ^ Colors, Contaminants and Toys - Regulatory Standards for Children's Confectionery SGS Consumer Compact Bulletin, Retrieved 11/14/2012
Further reading[edit]
External links[edit]


text:
Measuring tube sliding micrometer - Type: Standard
Measuring tube made of HPVC, telescopic coupling made of brass with high-precision conical measuring stop. Option: Water pressure-tight measuring tubes (double O-ring seal). Used for high-precision measurement axial displacement measurements in soil, rock and in boreholes in concrete structures.
1. Brass telescopic coupling mounted on HPVC measuring tube 2. Measurements in dam 3. Installation of measuring tube with injection packer

source: openbmb/Ultra-FineWeb


text:
Early in World War II, Kiska was a hotly contested battlefield that figured prominently in Japanese and U.S. news. Nearby, Adak supported a large military installation. In the new exhibition Kiska and Adak: War in the Aleutians, historic artifacts and then-and-now photographs illustrate the United States struggle to evict war-time intruders from Alaska.
Today, these islands are home to the physical remains of the World War II era. On Kiska, U.S. bomb craters dot the tundra and Japanese gun barrels point skyward, reminders of the air wars ferocity.
Digital art by Dirk H.R. Spennemann presents the Kiska battlefield filtered through an artists gaze. These photographs were taken during historic preservation fieldwork with the National Park Service and the U.S. Fish and Wildlife Service. Spennemann used digital darkroom techniques to create grittier images more evocative of the war.
Also on display are objects and photographs from the National Park Service and the museums World War II and Cold War collections. Objects include American and Japanese military gear and cartoons from the military newspaper The Adakian. There are also examples of trench art, which soldiers created using discarded items such as bullet casings.
The exhibition is on view at the Anchorage Museum
through December 31, 2010.


text:
What is it?
A run chart is a line graph of data plotted over time. By collecting and charting data over time, you can find trends or patterns in the process. Because they do not use control limits, run charts cannot tell you if a process is stable. However, they can show you how the process is running. The run chart can be a valuable tool at the beginning of a project, as it reveals important information about a process before you have collected enough data to create reliable control limits.
What does it look like?
Run charts show individual data points in chronological order.
When is it used?
Run charts are often used with baseline data at the beginning of a project. If you do not have enough data for control limits, CHARTrunner Lean and SQCpack let you switch the control chart display to a run chart and switch back when you have enough data.
Use run charts when you can answer yes to these questions:
Getting the most
Run charts should be used as a quick test of system performance. Start ups and short runs in manufacturing settings often produce too little data for conventional control chart analysis, but are easily analyzed in a run chart. Inspection data generated in these situations should be plotted immediately on a run chart to enable quick diagnosis of system changes over time or to identify signs that the process has begun to stabilize.
Run charts are good way to illustrate and share information with other departments. They are often used to post sales figures for all to see. Patterns and trends are much easier to see on a run chart than in a matrix of rows and columns.
Because run charts can be easily constructed, they are especially useful for one-time analysis of historical data.


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Soil Health Spotlight: Soil structure and aggregation
Soil structure is a way to describe how mineral and organic particles are arranged in the soil. Structure is an important characteristic because it influences how stable and resilient the soil is to disturbance and erosion. It also plays an important role in water infiltration, aeration, root penetration, carbon storage, and nutrient cycling. Measuring soil aggregates is one way to determine the structural status of the soil. Aggregates are the small-scale clumps of bound soil particles and organic matter ranging from a half inch in diameter to microscopic in size. In general, the bigger and more numerous the aggregates, the better structure your soil has. Stable soil aggregates can hold soil particles together against wind, rain, and traffic more effectively than unbound free agents because they are literally stuck together.
Aggregates are often divided into two groups: macroaggregates (pea gravel size) and microaggregates (smaller than a grain of sand). Each group serves a different role in carbon cycling. Macroaggregates can be an important source of easily available carbon for soil microbial activity but breakdown relatively quickly in response to disturbance in the soil. Microaggregates act as more long-term carbon storage where they protect small amounts of organic matter from microbial breakdown. These aggregates are far more stable and resistant to destructive forces. Microaggregates can be formed inside of macroaggregates, which highlights the importance of macroaggregate formation. If macroaggregates are broken before microaggregates can be formed, the long-term storage of organic matter in soil can be compromised.
Aggregates are formed by attractive forces between particles, held together by sticky "organic glues" exuded by microorganisms, and physically molded together by plant roots and soil animals (Figure 1). Preventing aggregate breakdown and enhancing the activity of plants and microbes are the primary ways agricultural management can improve soil aggregation.
Figure 1. Earthworms exude sticky glues which help to build soil structure. Photo from K-State Research and Extension.
The following management practices have been shown to improve soil aggregation:
- Reduced tillage or no-till – Reduces disturbance and increases plant residue return to soil
- Crop rotation – Enhances plant-microbe-soil interactions
- Cover crops – Enhances plant-microbe-soil interactions, increases plant residue return to the soil
- Adjusting soil pH or cation availability with amendments such as lime or gypsum (in case of sodic soils) – Can increase soil particle binding from calcium input and/or improve soil pH to facilitate plant and microorganism growth
Laura Starr, Ph.D. graduate student


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Looking to learn something new?
iOS Swift Collections and Control Flow Control Flow With Loops While and Repeat While
Michael Cronk
Michael Cronk
7,607 Points
I was just wondering if anyone could break this down and explain to me how this works...?
let numbers = [2,8,1,16,4,3,9] var sum = 0 var counter = 0
while counter < numbers.count { sum += numbers[counter] counter += 1}
Michael Cronk
Michael Cronk
7,607 Points
Thank You! That makes so much sense now.
1 Answer
Hey Michael, I've posted your code with my comments below. Hope this helps.
//declares an array of Int's named numbers
let numbers = [2,8,1,16,4,3,9]
//declares an Int variable named sum, initialised with a zero value
//used to keep track of the sum total
var sum = 0
//declares an Int variable named counter, initialised with a zero value
//this is used as an index value, as well as an indicative value
//to compare to the number of items in the numbers array
var counter = 0
//While Loop
//This should read as "While the counter is less than the amount of items in the numbers array, execute the below."
//While this conditional is true, the body of the loop will execute.
while counter < numbers.count {
 //The += operator takes the current value of sum, and adds
 //the number at the index specified by the counter property.
 //can also be written as sum = sum + numbers[counter]
 sum += numbers[counter]
 //We then add 1 onto the current counter property so that
 //the index next time will be one more than this execution.
 //If this was the last index in the array, the boolean
 //of the while loop condition will become false and stop executing
 //because the counter is now higher than the amount of items in the numbers array.
 counter += 1


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The Great Flood of 2011, Thailand: A Firsthand AccountDate: March 28th, 2012
Source: Centers for Disease Control and Prevention
Thailand has a tropical climate with monsoon rains that come every summer. In 2011, the rains were unusually heavy, with a sequence of typhoons sweeping across southeast Asia. Regions of Thailand are now experiencing the worst floods in over fifty years, as water immerses villages, farms, and factories. The volume of water is so vast that more than half the country has already been flooded.
|«||Disaster Movies: Lessons Learned||Tornadoes in Dallas & Fort Worth Areas – Recovery Information||»|
Keywords: cdc, flooding, floods, lessons learned, thailand


text:
us.
But ocean wallpapers are more than just visually pleasing; they also inspire us to explore and discover. By featuring hidden treasures such as shipwrecks, underwater caves, and mysterious sea creatures, these wallpapers ignite our curiosity and fuel our sense of adventure. They remind us that the ocean is a vast playground waiting to be explored, full of secrets and surprises that are just waiting to be discovered.
The deep blue hue of the ocean is known to have a calming and soothing effect on our minds. It evokes a sense of tranquility and peacefulness that can help us unwind and relax. By adorning our iPhones with ocean wallpapers, we can bask in the beauty of the deep blue and carry a piece of that serenity with us wherever we go. Whether we're stuck in traffic or waiting in line, a quick glance at our ocean wallpaper can transport us to a place of calmness and rejuvenation.
Moreover, ocean wallpapers allow us to indulge in the magic of the ocean. The vibrant colors, the playful dolphins, and the intricate coral reefs create a captivating and whimsical experience that can brighten even the dullest of days. They remind us of the wonders of nature and the joy that comes from exploring the unknown. With an ocean wallpaper on our iPhone, we can tap into our sense of wonder and rekindle our childlike curiosity.
In conclusion, ocean wallpapers for iPhones are a gateway to the majestic depths of the ocean. They bring beauty, tranquility, inspiration, and a touch of magic to our screens. By unveiling the hidden treasures of the ocean, these wallpapers remind us of the wonders that lie beneath the surface and encourage us to explore and discover. So, dive in, explore, and let the breathtaking ocean wallpapers mesmerize you with their splendor.
ocean wallpaper for iphone


text:
National Hot Chocolate Day
also:National Popcorn Day
What's the difference between Hot Chocolate & Hot Cocoa?
Hot Chcolate uses milk or milk chocolate while Hot Cocoa uses only powdered cocoa
Daily Fact: Chocolate is the 3rd most traded commodity in the world. 1st is oils, 2nd is coffee.
Make a "Sotuhern" Hot Chocolate:
add a dash of tabasco & a splash of Southern Comfort
Today's Food History
on this day in…
- 1893 The Atlanta based Coca-Cola trademark was recorded.
- 1930 Scotch tape was developed by Richard Drew of the 3M Company.
- 1980 Due to record high sugar prices, Coca Cola begins substituting high fructose corn syrup for half of the sucrose (sugar) used in Coca Cola.
- 1990 The first McDonald's restaurant in Moscow, Russia opens.
- 2001 Germany announced plans to destroy 400k cattle due to the mad cow crises. We know it now as Mad Cow Disease
more fun food facts at Birmingham's own


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Internal vs External Fragmentation
Difference between internal and external fragmentation is a topic of interest to many who like to improve their computer knowledge. Before knowing this difference, we have to see what fragmentation is. Fragmentation is a phenomenon that occurs in computer memory such as Random Access Memory (RAM) or hard disks, which causes wastage and inefficient usage of free space. While the efficient usage of available space is hindered, this causes performance issues, as well. Internal fragmentation occurs when memory allocation is based on fixed-size partitions where after a small size application is assigned to a slot the remaining free space of that slot is wasted. External fragmentation occurs when memory is dynamically allocated where after loading and unloading of several slots here and there the free space is being distributed rather than being contiguous.
What is Internal Fragmentation?
Consider the figure above where a fixed sized memory allocation mechanism is being followed. Initially, the memory is empty and the allocator has divided the memory into fixed size partitions. Then later three programs named A, B, C have been loaded to the first three partitions while the 4th partition is still free. Program A matches the size of the partition, so there is no wastage in that partition, but Program B and Program C are smaller than the partition size. So in part ition 2 and partition 3 there is remaining free space. However, this free space is unusable as the memory allocator only assigns full partitions to programs but no t parts of it. This wastage of free space is called internal fragmentation.
In the above example, it is equal sized fixed partitions but this can even happen in a situation where partitions of various fixed sizes are available. Usually the memory or hardest space is divided into blocks that are usually the size of powers of 2 such as 2, 4, 8, 16 bytes. So a program or a file of 3 bytes will be assigned to a 4 byte block but one byte of that block will become unusable causing internal fragmentation.
What is External Fragmentation?
Consider the figure above where memory allocation is done dynamically. In dynamic memory allocation, the allocator allocates only the exact needed size for that program. First memory is completely free. Then the Programs A, B, C, D and E of different sizes are loaded one after the other and they are placed in memory contiguously in that order. Then later, Program A and Program C closes and they are unloaded from memory. Now there are three free space areas in the memory, but they are not adjacent. Now a large program called Program F is going to be loaded but neither of the free space block is not enough for Program F. The addition of all the free spaces is definitely enough for Program F, but due to the lack of adjacency that space is unusable for Program F. This is called External Fragmentation.
What is the difference between Internal and External Fragmentation?
- Internal Fragmentation occurs when a fixed size memory allocation technique is used. External fragmentation occurs when a dynamic memory allocation technique is used.
- Internal fragmentation occurs when a fixed size partition is assigned to a program/file with less size than the partition making the rest of the space in that partition unusable. External fragmentation is due to the lack of enough adjacent space after loading and unloading of programs or files for some time because then all free space is distributed here and there.
- External fragmentation can be mined by compaction where the assigned blocks are moved to one side, so that contiguous space is gained. However, this operation takes time and also certain critical assigned areas for example system services cannot be moved safely. We can observe this compaction step done on hard disks when running the disk defragmenter in Windows.
- External fragmentation can be prevented by mechanisms such as segmentation and paging. Here a logical contiguous virtual memory space is given while in reality the files/programs are splitted into parts and placed here and there.
- Internal fragmentation can be maimed by having partitions of several sizes and assigning a program based on the best fit. However, still internal fragmentation is not fully eliminated.
Internal vs External Fragmentation
Both internal fragmentation and external fragmentation are phenomena where memory is wasted. Internal fragmentation occurs in fixed size memory allocation while external fragmentation occurs in dynamic memory allocation. When an allocated partition is occupied by a program that is lesser than the partition, remaining space goes wasted causing internal fragmentation. When enough adjacent space cannot be found after loading and unloading of programs, due to the fact that free space is distributed here and there, this causes external fragmentation. Fragmentation can occur in any memory device such as RAM, Hard disk and Flash drives.


masters and slaves. She draws on a wide range of sources, including epic and tragedy, historiography and philosophy, and art and architecture.
The Lost Books of Jane AustenThe Lost Books of Jane Austen
Janine Barchas
The Pursuit of ParenthoodThe Pursuit of Parenthood
Margaret Marsh, and Wanda Ronner
Bringing their unique expertise in gender history and women's health to the subject, Margaret Marsh and Wanda Ronner examine the unprecedented means—liberating for some and deeply unsettling for others—by which families can now be created. Beginning with the early efforts to create embryos outside a woman's body and ending with such new developments as mitochondrial replacement techniques and uterus transplants, the authors assess the impact of contemporary reproductive technology in the United States. The book dispels a number of fertility myths, offers policy recommendations, and reveals why the United States is still known as the "Wild West" of reproductive medicine.
Campus Sexual AssaultCampus Sexual Assault: College Women Respond
Lauren J. Germain
In Campus Sexual Assault, Lauren J. Germain focuses attention on the post–sexual assault experiences of twenty-six college women. She reframes conversations about sexual violence and student agency on American college campuses by drawing insight directly from the stories of how survivors responded individually to attacks, as well as how and why peers, family members, and school, medical, and civil authorities were (or were not) engaged in addressing the crimes. Germain weaves together women's narratives to show the women not as victims per se but as individuals with the power to overcome these traumatic experiences.
Brides, Mourners, BacchaeBrides, Mourners, Bacchae: Women's Rituals in Roman Literature
Vassiliki Panoussi
Feminist approaches to the study of women in Greek literature have helped illustrate the importance of their religious and ritual roles in public life—Latin literature, however, has not been subject to similar scrutiny. In Brides, Mourners, Bacchae, Vassiliki Panoussi takes up the challenge, exploring women's place in weddings, funerals, Bacchic rites, and women-only rituals. Panoussi probes the multifaceted ways women were able to exercise influence, even power, in ancient Rome from the days of the late Republic to Flavian times. The book elucidates not only the importance of female religious experience in Rome but also the complexity of ideological processes affecting Roman ideas about gender, sexuality, family, and society.
OutsidersOutsiders: Five Women Writers Who Changed the World
Lyndall Gordon
Mary Shelley, Emily Brontë, George Eliot, Olive Schreiner and Virginia Woolf: they all wrote dazzling books that forever changed the way we see history. In Outsiders, award-winning biographer Lyndall Gordon shows how these five novelists shared more than talent. We have long known the individual greatness of each of these writers, but in linking their creativity to their lives as outcasts, Gordon throws new light on the genius they share. Writing with passionate intelligence of her own, Gordon reveals that these renegade writers inspired a new breed of women who wished to change a world locked in war, violence, exploitation, and sexual abuse.
Victorians UndoneVictorians Undone: Tales of the Flesh in the Age of Decorum
Kathryn Hughes
In Victorians Undone, renowned British historian Kathryn Hughes follows five iconic figures of the nineteenth century as they encounter the world not through their imaginations or intellects but through their bodies. Or rather, through their body parts. Using the vivid language of admiring glances, cruel sniggers, and implacably turned backs, Hughes crafts a narrative of cinematic quality by combining a series of truly eye-opening and deeply intelligent accounts of life in Victorian England.
The Backwash of WarThe Backwash of War: An Extraordinary American Nurse in World War I
Ellen N. La Motte, edited with an introduction and biography by Cynthia Wachtell
In September 1916, as World War I advanced into a third deadly year, an American woman named Ellen N. La Motte published a collection of stories about her experience as a war nurse. Deemed damaging to morale, The Backwash of War was immediately banned in both England and France and later censored in wartime America. At once deeply unsettling and darkly humorous, this compelling book presents a unique view of the destruction wrought by war to the human body and spirit. This volume gathers, for the first time, La Motte's published writing about the First World War. In addition to Backwash, it includes three long-forgotten essays.
The Making of Jane AustenThe Making of Jane Austen
Devoney Looser
Just how did Jane Austen become the celebrity author and the inspiration for generations of loyal fans she is today? Devoney Looser's The Making of Jane Austen turns to the people, performances, activism, and images that fostered Austen's early fame, laying the groundwork for the beloved author we think we know. Looser shows how these figures and their Austen-inspired work transformed Austen's reputation, just as she profoundly shaped theirs. Drawing from unexplored material, Looser examines how echoes of that work reverberate in our explanations of Austen's literary and cultural power.
T.S. Eliot's Dialectical ImaginationT.S. Eliot's Dialectical Imagination
Jewel Spears Brooker
Jewel Spears Brooker argues that two of the principles that Eliot absorbed as a PhD student at Harvard and Oxford were to become permanent features of his mind, grounding his lifelong quest for wholeness and underpinning most of his subsequent poetry. The first is that contradictions are best understood dialectically, by moving to perspectives that both include and transcend them. The second is that all truths exist in relation to other truths. Brooker considers Eliot's poetry in three blocks, each represented by a signature masterpiece: "The Love Song of J. Alfred Prufrock," The Waste Land, and Four Quartets. She correlates these works with stages in the poet's intellectual and spiritual life: disjunction, ambivalence, and transcendence.
The Digital Literary SphereThe Digital Literary Sphere: Reading, Writing, and Selling Books in the Internet Era
Simone Murray
The Digital Literary Sphere considers the contemporary book world from multiple viewpoints. By examining reader engagement with the online personas of Margaret Atwood, John Green, Gary Shteyngart, David Foster Wallace, Karl Ove Knausgaard, and even Jonathan Franzen, among others, Murray reveals the dynamic interrelationship of print and digital technologies. Drawing on approaches from literary studies, media and cultural studies, book history, cultural policy, and the digital humanities, this book asks: How does digital media reframe the "live" author-reader encounter? And does the growing army of reader-reviewers signal an overdue democratizing of literary culture or the atomizing of cultural authority?
Northern Italy in the Roman WorldNorthern Italy in the Roman World: From the Bronze Age to Late Antiquity
Carolynn E. Roncaglia
Carolynn E. Roncaglia's Northern Italy in the Roman World analyzes the effect of the Roman Empire on northern Italy, tracing the evolution of the region from the Bronze Age to the Gothic wars. A wealthy and strategically important region, northern Italy presents an interesting case study for examining the influence of the Roman state on the fluctuating geographic areas of Cisalpine Gaul that were under its control. Using an array of epigraphic, archaeological, numismatic, and literary evidence, Roncaglia shows how Rome affected matters large and small, from loom weights to ritual horse burials, social networks to the careers of writers.
Sarah Gray Cary from Boston to GrenadaSarah Gray Cary from Boston to Grenada: Shifting Fortunes of an American Family, _PHONE_
Susan Clair Imbarrato
The Cary family of Chelsea, Massachusetts, prospered as plantation owners and managers for nearly two decades in the West Indies before the Grenada slave revolts of 1795–1796 upended the sugar trade. Sarah Gray Cary used her quick intelligence and astute judgment to help her family adapt to their shifting fortunes. From Samuel Cary's departure from Boston to St. Kitts in 1764 to the second generation's search for trade throughout the West Indies, Susan Clair Imbarrato draws on a wealth of archival material to tell the compelling story of the Cary family from prosperity and crisis to renewal.
The Notorious Mrs. ClemThe Notorious Mrs. Clem: Murder and Money in the Gilded Age
Wendy Gamber
In September 1868, the remains of Jacob and Nancy Jane Young were found lying near the banks of Indiana's White River. Suspicion for both deaths turned to Nancy Clem, a housewife who was also one of Mr. Young's former business partners. Wendy Gambler chronicles the life and times of this charming and persuasive Gilded Age confidence woman, who became famous not only as an accused murderess but also as an itinerant peddler of patent medicine and the supposed originator of the Ponzi scheme. The book raises fascinating questions about women's place in an evolving urban economy. Was Clem on trial because she allegedly murdered her business partner? Or was she on trial because she engaged in business?


How murders shed light on women's history
Before she moved to Indianapolis and got shady, she was a farm girl in Pike Township, doing farm chores for her family. She later ran a boardinghouse. She married a prosperous grocer.
Will Higgins
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Mrs. Nancy Clem from "The Cold Spring Tragedy" A. C. Roach, 1869.
"Crime is a very appealing way to get at larger social issues," says IU history professor and author Wendy Gamber. It also makes for a compelling story..
Crime gets readers' attention. "The Devil in the White City," about a serial killer during the 1893 Chicago's World Fair, was a best-seller. Leonardo DiCaprio is making a movie of it.
More important to academics such as Gamber, crimes usually are followed by trials. Trials are gold mines for historians. "You have attorneys on both sides telling their versions of what happened," Gamber said. "They have to make arguments that make sense and so they draw on the larger culture, and that illuminates some of the unstated beliefs of the larger culture."
Gamber's newest book, "The Notorious Mrs. Clem: Murder and Money in the Gilded Age," is about a grisly 19th century double homicide in Indianapolis. The book, published by Johns Hopkins University Press, was released in July.
Nancy Clem was tried for the killings of husband and wife Jacob and Nancy Young. Their mutilated bodies were found Sept. 12, 1868, on the banks of the White River. Jacob Young's face had been largely blown off by a shotgun blast. Nancy Young had been shot, then set on fire — the flesh on her thighs was gone and her intestines were exposed. "Burned to a crisp," is how the Indianapolis Journal put it.
It was an odd crime for a woman. It was violent and committed not out of passion but for business reasons. It was therefore sensational, and newspapers nationwide carried stories about the ensuing trials, five in all.
Vonnegut's 'Happy Birthday' opera finally comes of age
Central to both sides' legal arguments was Clem's lifestyle. Clem, despite having a prosperous husband and a young son, was a businesswoman. She and two partners, one of them Jacob Young, borrowed and lent money. It was a scam, but Clem was sketchy not for being a scammer, prosecutors argued, but rather simply for being in business. What kind of woman seeks self-reliance instead of being at home like a good wife?
Read strictly as a whodunit, "The Notorious Mrs. Clem" disappoints because it lacks closure. Despite her many days in court, Clem was not convicted of the killings, nor was anyone else. Technically the murders are unsolved, although Gamber is pretty sure Clem did them. And it's not entirely clear how her financial scam worked. It was likely a Ponzi scheme but might have also involved some loan-sharking.
The story does, however, shed considerable light on women's roles in the late 19th century economy, roles that were more substantive and varied than previously thought.
Hence, Gamber's interest. She has taught at Indiana University since the 1990s, and her research has focused on women and labor, mostly in the late 19th century.
"The Notorious Mrs. Clem" is her third book. Her first, "The Female Economy," is about female entrepreneurs who dominated dressmaking in the late 19th century. Both it and "Clem" poke holes in the principle known as "separate spheres" — the view of history that women were held to the "private sphere" of domesticity while men went into the "public sphere" to earn money and make big things happen.
Wendy Gamber,
Department of History, Indiana University
Interim Associate Editor, Journal of American History
Nancy Clem's work life was part of what drew Gamber to write the book. Before Clem moved to Indianapolis and got shady, she was a farm girl in Pike Township, doing chores for her family. She later ran a boardinghouse. She married a prosperous grocer and was a middle-class housewife living the bourgeois life within a few blocks of future President Benjamin Harrison (who would be the prosecutor at several of her murder trials). She became a scam artist.
Later, in prison, where she was sent briefly after being convicted not of murder but of perjury, Clem worked as a laundress. When she regained her freedom, she passed herself off as a "female physician" and peddled "female tonic." (Once, a Civil War veteran drank three bottles and died.)
Clem had options.
Other women did, too, and they pop up in the narrative: Rebecca Marot ran a used furniture store, where on the morning of the murders William J. Abrams, Clem's other business partner, tried to buy a gun; Josephine Stevens was a clerk at her mother's store, another place Abrams shopped for a gun. "There are working women all over the place," said Gamber. There's Ann Hottle, for one, Clem's dressmaker, who invested her life savings of $925 with Clem and lost it all. Other bit players in the Clem saga include a female hotelier, a female news reporter and female prostitutes. "There were women involved in all kinds of ways in the economy," Gamber said.
Although she was an industrious, strong-willed woman, Clem was no women's rights pioneer and was never embraced by the movement.
"I think certainly the women's rights convention that met in Indianapolis in 1869 didn't mention her," said Gamber. "The women who came to see the trial were horrified, including some of Indianapolis' best citizens, some of whom would have been involved in women's rights. Clearly she wasn't somebody who elicited a great deal of sympathy for women."
But her weird and well-documented life's story does offer a window into how things were for women in the workplace.
Clem died in 1897 and was buried in Crown Hill Cemetery next to her son in Section 17, Loty 43. Her headstone says only "Mother."
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|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|a scrap or morsel of food left at a meal.|
drinking vessel for ale or beer, widely used in northern Europe (especially Scandinavia, Germany, and the British Isles) and in colonial America from the second half of the 16th century until the end of the 18th century. The body is usually cylindrical, and it has a hinged lid (with or without finial), generally a thumbpiece, and a handle that is often in a scroll shape. On the handles of many 17thand 18th-century tankards are whistles that were used for summoning waiters. Though they were sometimes made of horn, carved ivory, pottery, and porcelain (all with metal mounts), tankards most often were made from precious metals, especially silver, and pewter. In the late 17th century certain large tankards appeared, commissioned by corporate bodies or guilds for presentation or ceremonial use. Reproductions of traditional tankard styles date from the 19th century and continue to be produced in the 20th century.
Learn more about tankard with a free trial on Britannica.com.


Hasselblad's Home is our invitation to you to join us behind-the-scenes at our headquarters in Gothenburg, Sweden for a more intimate look into the core of Hasselblad. Hear from our designers and engineers about our thoughts and processes behind the development of our medium format cameras and the philosophies underpinning the foundation of how we bring Scandinavian design and craftsmanship to creators around the world.
X System cameras are put through a precise production schedule in addition to rigorous testing and sensor calibration processes. Hasselblad cameras contain miniscule details that require the highest concentration in order to avoid any flaws. Additionally, some parts do need a human touch to achieve optimal results.
Each production technician follows a specific training process, which can vary from one hour to a few days, depending on their task in the assembly line, with many having refined their skills while working on Hasselblad cameras for over 30 years.
X System production is divided into five stages.
First, the parts are checked for cosmetic issues before they are registered with a serial number in the system, allowing us to trace their path from the start of assembly to final delivery.
After that, the production team programs the camera followed by full assembly and updating the system with the latest firmware.
Next, we test and calibrate the sensor unit.
After that is the digital unit test, where we adjust the focus, remove any dust, and test camera power, noise, and other elements of the camera, including removal of any potential hot pixels.
The final stage is the photo quality test. In this phase, images are taken in a studio environment, testing against colour charts for tonal accuracy, issues with glare and other scenarios. After an automatic system check, the photos are then manually inspected to look for any irregularities the previous automated tests might have missed. These potential irregularities are previously unknown issues which the system has not been programmed to look for.
The sensors are calibrated separately from the camera body in a calibration station. Over 700 images are taken, testing the sensor under various settings, and then a specialized software calculates compensation parameters and produces a calibration file specific to that sensor.
The most delicate part of the production process is cleaning the dust under the filter and sensor. In the sensor cleaning process, we use a special wipe and a mix of Ethyl and Isopropanol. This mostly takes place under a fume hood to avoid the health hazards that arise from smelling the alcohol. Additionally, you have to be very careful to not damage the sensor while cleaning.


Ingram Blog
Tips to Optimize Your Book Descriptions
By: Jake Handy (_USER_) and Margaret Harrison (_USER_)
(Excerpt from Metadata Essentials)
Your long and short book descriptions should be an accurate, compelling, and comprehensive guide to the inside of the book.
In this blog, we'll provide best practices designed to optimize your descriptive copy, both for machines (e.g. Amazon, Google and other search engines) and humans (potential readers considering the book) in general search and at retail stores.
Long Description
A long description (often simply just called the description) is exactly that: a lengthy, detailed description of the work you're distributing. Effective descriptive copy should meet established criteria and best practices for structure, length, and content, and it should provide rich, full information about the book.
Structure: Anatomy of a description
A well-constructed book description is critical for search engine optimization (SEO) and consumer conversion. Proper description structure comes in three parts: the headline, a detailed exposition, and a strong close.
 - Make it clear and punchy. Highlight the big things that matter about the book from a reader's perspective (genre, key topics and themes, major brands, awards). Get them to want to find out more or simply purchase based on what they've already seen.
 - A headline should have a strong selling focus—less about plot and the specific details and more about why a busy reader should want this book. If someone didn't know the book existed, what might they be looking for that would bring them to this book?
 - Remember that the headline will often be seen on retailer pages before consumers are prompted to "read more."
 - Make the text bold and follow it with a paragraph break.
 - Work in a couple keywords to help your title get indexed in search engines.
Detailed Exposition
 - If a consumer clicks "read more," you want them to find rich details about the book.
 - Convey the notable topics, themes, plot elements, and features of the book.
 - For fiction titles, describe the plot, settings, and key characters.
 - For nonfiction, detail the subjects covered, as well as important people, places, and things.
 - This is where you can "set the mood" and give readers an idea of the style and tone of the book.
 - Use paragraph breaks and bulleted lists as appropriate to add structure and break up large blocks of text.
Strong Close
 - Emphasize why someone should buy the book. If a potential consumer has read this far, they are interested—now make the sale.
 - Who is the book for? "Fans of….", "Great gift for…"
 - Consider including awards, nominations, and/or a strong review quote. (If included here, do not exclude them for their respective specific metadata attributes.)
Book description as seen on, captured December 2017.
Content: What to include
While it is not essential to incorporate every element listed here, these are the major components that impact online discovery and consumer-purchasing decisions. We strongly recommend that you include them in the description when and as appropriate:
 - Genres, topics, and themes
 - Important and directly related people and brands
 - Locations and time periods
 - Special features and selling points specific to the edition or format
 - Contributors' other titles, series, and awards
 - Audience or age appropriateness
 - Adjacent people, organizations, experience, media properties, and other important connections
 - Bestseller history, critical reception, and awards (these can be retroactively added to a description following the book's initial sales cycle)
Use consumer keywords, topics, and phrases to align your description with the ways in which potential buyers talk about and look for books. Speak their language!
HTML markup is accepted by most retailers in the description, and you should use it to include formatted and structured content:
 - Use paragraph breaks or break tags () to break up large blocks of text, making the description easier for search engines and human beings to parse.
 - Bold and italic text provides emphasis and draws attention to important points.
 - Bullet points are useful (for nonfiction descriptions in particular) to highlight key aspects of the book.
We recommend an overall copy length of 200–750 words, though some books will lend themselves more readily to longer descriptions than others. Typically, the more information you can provide, the better.
Within ONIX, the description has no real text limit, but most distribution platforms will place a character limit on it to prevent extremes. We recommend a maximum of 4,000 characters and a minimum of 200 characters.
Short Description
The short description can be thought of almost as an expanded headline, however be careful to not just repeat your headline. The short description should vividly and precisely describe what a consumer would want to know about the book in as few characters as possible, while also conveying what sets it apart from other novels that may share similarities.
Often, distributors will display the short description and cover art or brief metadata about your book alongside various other products. Therefore, it's important that your book's cover art and short description deliver a one-two punch that compels consumers to dive in and learn more.
The ONIX character limit for a short description is 350 characters, but we recommend something even more concise, around 150 to 200 characters.
In closing, a book's short description and long description are rarely displayed side-by-side and should work in tandem to complement each other and provide a rich and vivid narrative. The short description should house what you believe buyers will find most important, prompting them to take the next step to the long description, where further attractive details await in the headline and beyond.
Metadata Essentials Book
Metadata Essentials: Proven Techniques for Book Marketing and Discovery provides clear and easy-to-implement recommendations so you can focus your efforts on the industry's most relevant metadata. For more information and to purchase the book, click here.
Ingram's Book Metadata Enhancement Service
Smart Metadata, from Ingram, is a book metadata improvement service that helps you improve your books' discoverability through data-driven analysis and industry expertise.
Learn More:
Why Does Metadata Matter?
Improve the Book Metadata that Matters
Make Your Books More Discoverable with a Good Description & Author Bio
Metadata for Books: The Current Landscape
How Books Are Discovered Online


Income Tax Calculators.
Tax and Finance Calculators
What is it Provisional Tax?
Provisional tax is not a separate tax. It is a method of paying tax due, to ensure the taxpayer does not pay large amounts on assessment, as the tax liability is spread over the relevant year of assessment.
It requires the taxpayers to pay at least two amounts in advance during the year of assessment these are based on estimated taxable income. A potential third payment is optional after the end of the tax year, but before the issuing of the assessment Final liability. This is worked out upon assessment and the payments will be offset against the liability for normal tax for the applicable year of assessment.
Who does Provisional Tax affect?
Any person who receives income other than a salary is a provisional taxpayer. A provisional taxpayer is defined as any:
Excluded from being a provisional taxpayer as defined are any:
Persons who are exempt from paying provisional tax, namely:
There is no formal registration or deregistration needed to be a provisional taxpayer. If a taxpayer is liable for provisional tax, he or she merely needs to request and submit an IRP6 return via eFiling to SARS.
How do I work out the amounts due?
The amount of provisional tax payable is worked out on the estimated taxable income for that particular year of assessment as shown below:
The First Period:
The Second Period:
The Third Period (voluntary):
How should Provisional Tax be paid?
SARS has introduced changes to provisional tax that affect the way in which provisional taxpayers file their IRP6 returns. With most provisional taxpayers making their submissions electronically, SARS will no longer post out (mail) IRP6 returns to provisional taxpayers nor can it be downloaded on the SARS website. You will now be asked to send your IRP6 using one of the methods below:
When should Provisional Tax be paid?
Please remember that late submissions could lead to you being charged with penalties and interest by SARS.


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Painter, Muralist, Printmaker, Illustrator
New York, N.Y.
Collection size: 24.8 linear feet
Collection Summary: Abraham Rattner's papers provide insight into an important time for twentieth century American art and culture. By studying Rattner's papers, the researcher may view the beginnings of Modernism, the cultural change that pushed the boundaries of artistic and literary traditions and provided new ways in which to express ourselves.
Biographical/Historical Note: Abraham Rattner (_PHONE_) was a painter, mosaicist, and stained glass artist from Paris, France and New York, N.Y. Studied art and architecture at George Washington University, the Corcoran School of Art in Washington, D.C., and the Pennsylvania Academy of the Fine Arts in Philadelphia. In 1917, he enlisted in the U.S. Army camouflage section. Married first wife, Bettina Bedwell, in 1924. Was a member of the Minotaure group, along with Picasso, Miro, Giacometti, Le Corbusier, Braque, Dali, and Reverdy. Rattner and his wife fled Europe in 1939 following the Nazi invasion of France. He married second wife Esther Gentle (_PHONE_) in 1949. Rattner died of heart failure on February 14, 1978.
The collection was given to the Archives of American Art in stages by Abraham Rattner _PHONE_, by Esther Gentle _PHONE_, and by Gene Allen in 1992. The donated material that was previously filmed has been integrated and refilmed includes reels D203 and D205C-D205D. The material found on reels D205A-D205B was loaned by Rattner and the material found on reel 1212 was loaned by his sister, Jennie Allen.
Processing and microfilming were made possible by a grant from the Judith Rothschild Foundation.
How to Use this Collection
- Read the Finding Aid for this collection
- The bulk of the collection is available on microfilm reels 5258-5279. The microfilm is available for interlibrary loan.
- Use of original papers requires an appointment and is limited to the Archives' Washington, D.C., Research Center. Microfilmed materials must be consulted on microfilm. Contact Reference Services for more information.
- For more information on using the Archives' resources, see the FAQ or Ask Us.
Also in the Archives
- Abraham and Esther Rattner letter to Helen Kroll Kramer, undated
- Oral history interview with Abraham Rattner, 1968 May-June
- Image Gallery items from other collections related to Rattner, Abraham


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Learning, experimentation, and monetary policy
We present a model of monetary policy where the policymaker faces uncertainty about wich he is learning in a Bayesian fashion. A fixed money supply levels. A fixed money supply rule is not optimal in this context since the learning leads to constant adjustments in money supply levels. We present cases in which it is optimal to bear some cost in terms of current output performance in order to gain information that can be used in the formulation of future monetary policy : experimentation therefore pays. We also show that even passive learning without experimentation still leads to an activist monetary policy, i.e. one that is constantly changing in response to new information.
(This abstract was borrowed from another version of this item.)
When requesting a correction, please mention this item's handle: RePEc:eee:moneco:v:32:y:1993:i:1:p:169-183. See general information about how to correct material in RePEc.
If references are entirely missing, you can add them using this form.


October 2019
Beyond books_0
The image is a graphic called "Censorship by the numbers." The main text reads: "Beyond Books. The American Library Association has noticed an increase in attempts to censor drag queen story hours and LGBTQIA+ programming, as well as challenges to remove access to data bases." The next panel shows a graph. The text reads: "The American Library Association's Office for Intellectual Freedom tracked 347 challenges in 2018. Here's the breakdown. 62% books. 15% programs, meeting rooms. 10% databases, magazines, films, games. 6% displays, artwork. 7% Other (includes access, social media, hate crimes." The graphic was created by the Office for Intellectual Freedom American Library Association.


ComEd Owned Street Light Audit
Like a lot of communities around Chicago, The Village of Glencoe has a small collection of street lights that they own and maintain. The rest of the lights are owned and maintained by ComEd, and The Village is then billed for their usage. ComEd provides The Village of Glencoe with a list of all the lights in its database that are within Glencoe's village limits. The Public Works department asked the GIS Department to see if all the lights could be mapped out and then analyzed to make sure that The Village was being billed correctly and that ComEd had the right information for each street light that they owned.
The GIS Department began using a combination of address information, aerial imagery, and Google Streetview to find the locations of each street light provided by ComEd. First, the street light locations were mapped against the Village's address and street range databases placing them in the general vicinity. Then by using a combination of aerial imagery and Google Streetview, the locations of each light were narrowed down. Any street lights in the ComEd database that can't be mapped will be then marked in the database and the Village will have to have discussions with ComEd to figure out the discrepancy. When the street light mapping is completed, The Village of Glencoe will then be assured that they are being billed correctly for their street light usage and that their own street light database is up-to-date.


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Stress has become a common problem in today's fast-paced world. From work pressures to personal issues, stress can take a toll on our overall well-being. If you're looking for a natural solution to combat stress, organic amla powder might be the answer you've been searching for.
What is Organic Amla Powder?
Amla, also known as Indian gooseberry, is a fruit that is highly regarded in Ayurvedic medicine for its numerous health benefits. It is rich in vitamin C, antioxidants, and other essential nutrients. Organic amla powder is made by drying and grinding the amla fruit, preserving its nutritional value.
How Does Organic Amla Powder Help with Stress Relief?
Organic amla powder is known for its adaptogenic properties, which means it helps the body adapt to stress and promotes overall well-being. Here's how it can help with stress relief:
- Reduces Cortisol Levels: Cortisol is a hormone released in response to stress. High cortisol levels can lead to anxiety and other stress-related symptoms. Organic amla powder helps regulate cortisol levels, reducing stress and promoting a sense of calm.
- Boosts Immune System: Stress weakens the immune system, making us more susceptible to illnesses. The high vitamin C content in organic amla powder strengthens the immune system, helping the body fight off stress-induced illnesses.
- Enhances Mood: Organic amla powder contains natural antioxidants that help improve mood and reduce feelings of anxiety and depression. It promotes the production of serotonin, a neurotransmitter responsible for feelings of happiness and well-being.
- Provides Nutritional Support: Stress can deplete the body of essential nutrients. Organic amla powder is packed with vitamins, minerals, and antioxidants that nourish the body and support overall health.
How to Use Organic Amla Powder for Stress Relief
There are several ways to incorporate organic amla powder into your daily routine:
- Drink Amla Juice: Mix organic amla powder with water to make a refreshing and rejuvenating drink. Drink it in the morning to kickstart your day with a boost of energy and stress-fighting nutrients.
- Add to Smoothies: Blend organic amla powder into your favorite smoothie recipe for an added nutritional punch. It pairs well with fruits like bananas, berries, and mangoes.
- Mix with Honey: Combine organic amla powder with honey to create a natural stress-relieving paste. Consume a spoonful of this mixture daily to experience its calming effects.
- Use as a Face Mask: Organic amla powder can also be used topically to promote skin health. Mix it with water or rose water to create a face mask that helps reduce stress-induced skin issues like acne and inflammation.
Organic amla powder is a natural and effective way to combat stress and promote overall well-being. Its adaptogenic properties, immune-boosting abilities, and mood-enhancing benefits make it a valuable addition to your daily routine. Try incorporating organic amla powder into your diet and lifestyle to experience its stress-relieving effects firsthand.
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02 Jan 2019
Both Cloud Datastore and Firestore automatically index most of the fields in your database models.
For example, if you use Cloud Datastore with Python 2 on the Standard GAE Environment, you'd create your database model like this:
class User(ndb.Model): name = ndb.StringProperty() age = ndb.IntegerProperty() active = ndb.BooleanProperty()
By default, all three fields would be indexed. But if you don't want some (or any) of them to be indexed, you can set their
indexed attribute as False:
class User(ndb.Model): name = ndb.StringProperty(indexed=False) age = ndb.IntegerProperty(indexed=False) active = ndb.BooleanProperty(indexed=False)
You can read more about optimizing indexes in this article: Optimizing Indices In Google Cloud Datastore - How And Why?
But what if you use the new GAE Python Standard Environment, which uses Python 3 and Cloud Firestore?
You'd have to disable field indexing via the Firebase Console.
Open your Firestore database in the Firebase Console. Click on Indexes and choose the Single field tab.
This page will show up:
Then scroll down to the Exemptions section:
Click on Add exemption and add the model name and the field you'd like to have exempted from indexing:
Click Next and disable the indexes you'd like to have exempt:
Voila! You've successfully exempted a field from having an index created which will save your database storage costs.


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ESSAYS ON THE ECONOMICS OF EDUCATION
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In the first chapter I study racial differences in the impact of education on labor income volatility. Using panel data on black and white males from the Panel Study of Income Dynamics I find that education reduces labor income volatility more for blacks than for whites. The central specifications indicate that college graduation reduces transitory labor income volatility by more than 65 percent relative to high school dropouts for blacks, whereas whites receive no statistically significant reduction. I also find that more risk averse blacks obtain more education while more risk averse whites do not. I argue that these results imply: (1) that precautionary demand for human capital is quantitatively important; and (2) the black differential investment puzzle can be explained by accounting for racial differences in the impact of education on exposure to labor income volatility. The results can be explained by the precision of employer's beliefs about a worker's productivity increasing more with education for blacks, so that more-skilled blacks face less labor income volatility. Participants, like econometricians, may have difficulty in constructing the counterfactual outcome required to estimate the impact of a program. In this chapter, this question is directly assessed by examining the extent to which program participants are able to estimate their individual program impacts ex-post. Utilizing experimental data from the National Job Training Partnership Act (JTPA) Study (NJS) experimentally estimated program impacts to individual self-reports of program effectiveness after the completion of the program are compared. Two methods are implemented to estimate the individual experimental impacts based on: (1) subgroup variation; (2) the assumption of perfect rank correlation in impacts. Little evidence of a relationship between the experimentally estimated program impacts and self-reported program effectiveness is found. There is evidence found that cognitively inexpensive potential proxies for program impacts such as before-after differences in earnings, the type of training received, and labor market outcomes are correlated with self-reported program effectiveness.


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An exploration into new mechanisms for jacquard weaving, as well as an ongoing interest in asking how non-human materials or forces can be engaged as collaborators resulted in the prototype of the wind loom—a modified tapestry loom that with every 4th warp connected to a sail that moves the warp position in and out. The fabrication of the loom was led by Jen Mah and Rachel Bork, who iterated between several prototypes for laser-cut heddle/hooks that can be attached to the yarn, arms are connected to umbrellas that can move when the wind blows, easily attachable and detachable components to support easy travel, and so on. The prototyping process was complex and frustrating, as the summer in which we prototyped was not very windy and it was hard to test in its specific working conditions we imagined for the loom. Local weaver, and friend, Julie Rodriguez, took the prototype out for a test and captured the photo above. Her approach was to wait for a gust, and then weave into the wind-produced shed with alternating colors that she chose.
The image on the left shows a detail of the arm design and how it connects to the warp yarns. First, a small piece of laser-cut acrylic attaches to the yarn. We cut a small "pig tail" in the acrylic to allow the small rectangular joint to be easily wound on and off the warp. That piece then fits into an arm that pivots around a post along the width of the loom. That arm has a long thin aluminum post attached to the back of it, upon which a we attach umbrellas made with nylon and 3D printed attachment joints. The length of the aluminum post determines the speed a which the umbrella will move. The longer the post, the weaker the wind. We found the weakest wind we could capture was roughly 6 mph. We originally had a second 3D printed joint between the metal post and the umbrella post (seen below) but this added to much weakness into the joint and became unruly in a wind gust. All of our part files and instructions can be found on this Instructables post: _URL_
The back view of the loom during development. We staggered the umbrella height in order to activate certain warps at certain speeds and to also make sure all of the umbrellas could fit into the space.
To prevent the arms from moving in directions not along the direction of the wind, we had to fabricate supporting "tracks" out of acrylic. These held the arms in place without inhibiting their movement (as we found with packing spaces with metal rings.). To help someone easily assemble and disassemble and travel with the loom, we made this track fixed by magnets, which worked well to hold it in place.
Here is a front view of the loom in development, with a bit of a tester tapestry in production based on some hypothetical wind data.
The insights from this is that the machine for weaving with the wind is incredibly frustrating to use. Mostly because the whole apparatus is large and the design of the umbrellas only catches wind traveling in one direction. While I initially considered redesigning to a smaller form, and reworking the umbrella design, I enjoy the idea of this machine being one that invites frustration. If the goal is to collaborate with an uncertain and unpredictable force, maybe frustration is precisely what ought to occur. Maybe it helps us confront our own limitations.
We used a GoPro to capture each step in the process of weaving a smart textile and compiled roughly 6 weeks of work into this video. We show the two tapestries that emerged from this weave, one that didn't work so well and the other that did (see force fabric post below). in both cases, we were attempting to weave structures that could be used to sense force and tigger color changes in response.
This is a first prototype of a vision of a force-fabric. When integrated into a garment, this textile could capture and replay how your body made contact with other bodies in the world. Those bodies may be human, created through the experiences of hugs or holding children, but they may also be of nonhuman forces – heavy winds or couches pressed upon ones back. The concept is to think of ways technology can make us aware of how we are physically supporting and supported by other objects and environmental forces. It sees garments as a interesting surfaces of intersection between self and other.
We created this first textile by double weaving sections of color changing yarn (resistive heating wire painted with a mixture of thermochromic pigments that change at different temperatures) on the front face and then integrating conductive pads on the back or under layer of the fabric. We used a tapestry technique to integrate a second piece of conductive yarn along a segment of the warp above the touchpad such that when it is pressed it completes the circuit. The double weaving structure makes the connective "guts" invisible from the front. Thus, the textile does not invite you to touch and poke it (how would you know where to touch), it simply captures a "picture" of the different press regions.
For those interested in recreating something like this, here are some information to work from. This draft shows the general structure of each touch pad, which leverages the structure of double weave to hide the conductive pads on the back of the fabric and highlight the thermochromic on the top.
Yarn Selection I hand dyed sections of the warp to achieve something ikat-like, largely taking inspiration from documentation of a warp painting class at my local weaving shop. The colors turned out so much darker and astro-pop looking than I was hoping but, luckily, when I mixed them into the warp, they mellowed out. The idea was to make the overall feel of the fabric less square and more painterly. I chose the colors to complement the transition states of the thermochromic yarns.
We used the conductive yarn we had on hand for the sensing (and sadly, we don't know where it came from) but it appears to be entirely made of stainless steel fibers which have been spun. The fibers like to "grab" the other yarns and they feel really nasty in the hand. I did one experiment adding them along the warp, which was a disaster as they grabbed the other yarns creating massive knots during warping and then broke frequently. On the plus side, they are easy to repair by just trying them back together.
We experimented with several methods for creating the color changing yarns. Playing around with combinations that could couple the painted fiber with a heating element. In some cases, we hand-spun the fibers together (shown in the figure below) with a conductive wire (38, 40AWG magnet wire) but that was finicky and prone to breaking.
We had the best results hand painting a cotton covered copper yarn we sourced from wires.co.uk. The thinner the wire, the better the heating. What seems to make this yarn work so well is that the copper inside the cotton covering is uninsulated, so lots of heat travels between the wire and cotton. It also makes for much more pleasant soldering and attaching.
Thermochromic Paint Mixture
We created our final paint mixture by mixing:
3 parts blue thermochromic that activates at 28°C;
1 part red thermochromic that activates at 43°C;
4 parts liquitex clear acryllic gel medium.
We cut lengths of our wire/yarn and then painted by hand. This makes it a little gloopy and uneven, but it works. The transition from purple to red to blue was the most notable in our experiments. The image below shows two different transitions between purple, blue or red, and white. You can see how the pink/red transition is much more visible.
The general structure of the weave puts the thermochromic sections on the top of the fabric while hiding the conductive yarns behind the fabric. The design follows the schematic outlined below:
The general rule of thumb was that one needed two rows of cotton yarn in between a conductive yarn to prevent unintended crossing. Here is a structural view of the yarn paths and draft of the top layer yarn for a SINGLE section of color change:
You can see the black yarn is the cotton, the purple is the thermochromic, and the teal is a second segment of cotton. The thermochromic leads are routed through the "middle" or between the two layers until their are integrated into the visible surface of the yarn.
Here is a draft and yarn paths for the BOTTOM layer that has the press pads. The green is our conductive yarn, the grey is the cotton yarn, and the red is a funny little yarn we call a "warp insertion." basically, it is a yarn we route through the bottom of the weave to reach the center point of the press pad and then manually pull through the warp using a crochet hook. This adds the yarn to the surface while making it very hidden.
Tie Ups Here is a tie up for the pattern. The frame threading is correct but I did lots of improvising on the treadles, so that is not correct for the drafts you see above. I also had to do lots of manipulations by hand.I made this in Excel, which can BARELY handle all of the information. Again, click to make larger.
Next Steps We have created our own smart textiles design software, AdaCAD, that helps immensely with drafting smart textiles. We expect to release this on GitHub once we have it fully integrated and talking to our TC2 loom. It will be released with a GPL license and we would like the community to get involved in development.
With the TC2 loom, we hope to recreate this general structure to create a wearable


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Rotation of the midgut happens during the second month of intra-uterine life. This is the gastrointestinal tract, consisting of the foregut, the hindgut, and the midgut. The midgut is continuous with the vitelline duct or yolk stalk, which later becomes obliterated.
Here's the aorta, here are the three arteries that supply the GI tract: the celiac for the foregut, the inferior mesenteric for the hindgut, and the superior mesenteric for the midgut.
As the midgut develops it protrudes into the body stalk forming a loop, with the superior mesenteric artery forming the axis of the loop.
As it protrudes, the midgut loop makes a quarter turn counter-clockwise, so its distal part is to the left and its proximal part is to the right. The distal part of the loop develops a bulge that will become the cecum, and the proximal part of the loop becomes quite convoluted.
During the time these changes are happening, the body continues to grow, and the abdominal cavity becomes large enough to allow the midgut to return.
The proximal part of the loop returns first. It passes under the distal part, and over to the left, that's towards us in this view. The distal part of the loop returns last. It passes in front of the proximal part, and ends up over to the right.
Let's look at the same sequence of events from in front and somewhat to the left, so that we can understand how these changes produce a rotation of the midgut.
Here's the midgut loop protruding towards us, and making its first quarter turn counter clockwise. A bulge appears for the cecum, and the proximal part of the loop becomes convoluted.
The abdomen becomes larger, and the proximal limb of the loop returns. It passes under the distal limb, in effect making another quarter turn counter clockwise. Then the distal limb returns, completing the third quarter turn. This proximal part of the midgut, the distal duodenum, ends up behind this distal part of the midgut, the proximal transverse colon.
Understanding those developmental changes helps us understand not only where the duodenum lies, but also why the colon is where it is.


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It would be technically possible to culture P. acnes from a friend; however, for purposes of a science fair project, it would make getting approval much more challenging. Culturing unknown bacteria requires preapproval and access to a BSL-2 laboratory. If you want to try this, you should write up your project proposal and submit it for approval right away. There are lots of unknown microorganisms on human skin and you would have a lot of work to do to verify the identity of P. acnes. _URL_ ents.shtml
However, it would be easier to obtain a pure culture of an organism so you can work in a BSL-1 laboratory. Carolina Biologicals sells a garden variety E. coli for classroom use that is easy to grow.http://www.carolina.com/product/living+... estMatches
Micrococcus luteus is another possible organism, and it is a Gram positive bacterium like P. acnes.http://www.carolina.com/product/living+... y=ourPicks
P. acnes is available from the American Type Culture collection, but it prohibitively expensive. It might be possible to obtain a culture from a laboratory that has this organism in their stock culture collection. _URL_ e=bacteria
Your idea of making infusions of the herbs is a good idea. Have you tried searching for the chemical composition of the herbs to identify what components might be effective antimicrobial agents? Since acne is an inflammatory response to the presence of the microorganism, some acne medications are anti-inflammatory compounds and you would not expect to see any effect of these compounds on microbial growth. If a compound works against E. coli, you would not be able to say for sure that it would work against P. acnes.
If you are going use a light bulb as a source of heat for your incubator, you need to make sure that the temperature does not exceed the maximum limit for the microorganism that you are using. It is easy to "cook" bacteria and kill them. The optimum temperature for E. coli is about 37 degrees Centigrade, and the maximum is in the low 40's degrees C. It would be better to have an incubator that is a little cooler to ensure survival. Be sure to test your incubator and verify that it will maintain a temperature between 30 and 37 degrees C.
What are you going to use as a control? How are you going to measure your results?


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Posted: Feb 28 2020
We are excited to be carrying Magna-Tiles, the original 3D magnetic building tiles by Valtech since 1997. With so many ways to learn, play and create, Magna-Tiles are a great addition to any toy room. The magnets are safely secured inside of each shape. These durable tiles are made with food-grade ABS (BPA FREE) plastic which is free of phthalates and latex. They can even be fully submerged in water for cleaning.
Here are some ideas for using your Magna Tiles:
Name Those Shapes
Having children identify shapes is just one way you can use Magna-Tiles to teach children math concepts. From sorting and counting to angles and geometry, children of all ages can learn the math skills they need while creating fun Magna-Tiles creations.
Explore Science Concepts
Magna-Tiles are a lot harder to knock over than traditional building blocks thanks to each tile having magnets on all sides. Children can start learning about magnetic principles, gravity, and other science concepts as soon as the tiles come out of the box.
Build 3-D Structures
Children will also learn basic engineering skills as they use Magna-Tiles to build a variety of simple and complex 3-D structures.
Whether they're building a house or their own unique design, children can use Magna-Tiles to create a variety of structures and designs. You can also ask children to come up with fun stories about the structures they're building to help them practice their literacy skills.
Develop Fine Motor Skills
Magna-Tiles also serve as a great manipulative for children, because they can have fun building structures as they develop the fine motor skills they need.
Teach Critical Thinking
Learning how to build a variety of Magna-Tiles creations will help children develop critical thinking and problem-solving skills.
So how will you play with yours?


The Pages app on your iPad is the word-processing and page-layout tool in the iWork suite of apps. As is the case in most word-processing programs, a ruler at the top of a page in Document Editing view lets you set basic formatting.
The ruler can be hidden, but tapping in the document displays it, as shown in this figure. Tapping text also displays the formatting toolbar along the bottom of the screen, as shown in this same figure. The small X-in-a-circle to the right of the ruler lets you hide the ruler when you no longer need it.
The ruler shows you the settings for whatever is selected in the document. Tap text in the document, and the ruler is immediately enabled and reflects the settings for the selection (in this case, the margins). Tapping in the document may also bring up the onscreen keyboard, and selection buttons, as shown in this figure. You can use them to use features such as cut, copy, delete, and paste.
A single tap brings up the selection buttons, a double-tap selects the word at the insertion point, and a triple-tap selects the paragraph and brings up slightly different selection buttons.
The Formatting bar along the bottom of the screen provides basic formatting for the current selection. The tools on the ruler that can be used on the selection (from left to right in the figure) are described in this list:
 - Tab: Tap this button to set new tab stops.
 - Indent: Tap either of the Indent buttons to indent text in one level or out one level at a time.
 - Font: In the figure, the font is Helvetica Neue. Tap the font name to open a popover with a list of fonts to select from.
 Note that available fonts in Pages on iPad are fewer than in Mac or Windows programs, and you can't add fonts as you can on a computer. So if a font isn't supported on iPad, another font is substituted, which could affect layout and appearance adversely.
 - Font Size: Tap the large A on the right to enlarge selected text by one point; tap the smaller A on the left to decrease the text size. By using the tool in the middle, you can set the font size to an exact number.
 - Font Styles: You can choose bold, italic, or underlining.
 - Alignment: The selected paragraph can be aligned to the left, center, or right, or justified so that both margins are straight with no ragged edges. You don't have to select the paragraph with a triple-tap for alignment to work. If you have selected a word or an insertion point, the paragraph containing either item is the selected paragraph.
 - Insert: Tapping the last button on the Formatting toolbar displays a menu of insertion commands including Comment, Link, Page Break, Column Break, or Footnote.
Feel free to experiment with the formatting within your Pages documents, and remember that the Undo button in the upper-left is there to help you out if you change your mind about something you've done.
Most buttons on the ruler require you to simply tap them, but some (for example, the Fonts and Font Size buttons) open their own popovers for further selections; refer to the figure, which shows the Fonts popover.
You can also use the ruler to set the margins for paragraphs. Just slide the indicators along the ruler. Note that the top indicator for the left margin reflects the margin of the first line in a paragraph; the lower indicator is the left margin of all other lines in the paragraph.
You can indent the first line of a paragraph, but you can also outdent it (or provide a hanging first line); an outdent works well in a list.


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Тип публикации: доклад, тезисы доклада, статья из сборника материалов конференций
Конференция: Australasian Congress on Applied Mechanics, ACAM 2017; Sydney, NSW; Sydney, NSW
Год издания: 2017
Аннотация: Traditional rheological method is supplemented by a new element called rigid contact, which serves to take into account different resistance of materials to tension and compression. Based on this method, mathematical model describing deformation of a porous medium is constructed, which takes into account change in the resistance to external mechanical impact at a moment of collapse of pores. Parallel computational algorithm is developed for the analysis of dynamics of porous materials, accompanied by plastic deformation of skeleton and collapse of pores. This algorithm is tested on supercomputers in the problems about propagation of plane longitudinal compression shock waves and the expansion of cylindrical cavity in an infinite porous medium. The solutions of these problems are obtained in closed form in the framework of the suggested mathematical model. It is shown that, depending on the porosity of the medium and the value of the yield point, the instantaneous loading of a half-space with constant pressure leads to the formation of one or two shock waves – an elastic longitudinal wave, a plastic wave or waves of elastic or plastic compaction. Critical pressures of limit states and radii of interfaces between characteristic zones of plasticity and compaction are calculated numerically in the problem of radial expansion of cavity with sufficiently high precision.
Журнал: 9th Australasian Congress on Applied Mechanics, ACAM 2017
Выпуск журнала: 2017-November
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