Cryptosporidium in Mice

In an Unexpected Research Finding, Infections with the Intestinal Parasite, Cryptosporidium parvum, Worsened in Mice that had Been Given a Probiotic.
The research was published in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

August 31, 2018 -- As compared to control mice, the probiotic-consuming mice excreted more parasites in their feces, and their intestinal microflora were different from those of the control mice. However, both sets of microflora were composed of genera that normally are present in the gut, and the mechanisms responsible for the observed probiotic effect are unclear, said corresponding author, Giovanni Widmer, PhD, whose graduate student, Bruno Oliveira, ran the experiments.

Contrary to expectations, "we found that consumption of a commercially available probiotic actually increased the severity of the infection," said Dr. Widmer, who is Professor of Infectious Disease & Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA.

Cryptosporidiosis is a major cause of infant diarrhea in developing nations. It killed an estimated 48,000 people worldwide in 2016, and caused the loss of more than 4.2 million disability-adjusted life-years, according to The Lancet, a medical journal. There are neither drugs to treat cryptosporidiosis, nor vaccines to prevent it. (image: high magnification micrograph of cryptosporidium infection, Wikimedia Commons)

Antibiotics, which often perturb or even deplete the normal intestinal microbiota, can thus render individuals more vulnerable to intestinal infections. Conversely, a healthy microbiome can prevent such infections, or reduce their severity. Reasoning along these lines, the researchers posited that a probiotic containing live microorganisms that are found in healthy intestines could reduce the severity of cryptosporidiosis in a mouse model.

"Mitigating the disease's severity may be sufficient to prevent diarrhea, or shorten its duration, and enable the immune system to naturally control the infection," said Dr. Widmer.

Despite an outcome that was contrary to the working hypothesis, the results demonstrate that it may be possible to develop probiotics to mitigate cryptosporidiosis. Prior to the experiment, "we didn't know if cryptosporidium growth in the gut could be affected by diet," said Dr. Widmer. "The goal is now to find a mechanistic link between microflora and cryptosporidium proliferation, and ultimately design a simple nutritional supplement which helps the body fight the infection."

"Identifying specific mechanisms that alter pathogen virulence in response to diet may enable the development of simple pre- or probiotics capable of modifying the composition of the microbiota to reduce the severity of cryptosporidiosis," said Dr. Widmer.

https://www.sciencedaily.com/releases/2018/08/180831133203.htm

Mammalian Brain Evolution

Mammal Forerunner that Reproduced like
a Reptile Sheds Light on Brain Evolution

Science Daily – August 29, 2018 -- Compared with the rest of the animal kingdom, mammals have the biggest brains and produce some of the smallest litters of offspring. A newly described fossil of an extinct mammal relative -- and her 38 babies -- is among the best evidence that a key development in the evolution of mammals was trading brood power for brain power.

The find is among the rarest of the rare because it contains the only known fossils of babies from any mammal precursor, said researchers from The University of Texas at Austin who discovered and studied the fossilized family. But the presence of so many babies -- more than twice the average litter size of any living mammal -- revealed that it reproduced in a manner akin to reptiles. Researchers think the babies were probably developing inside eggs or had just recently hatched when they died.

The study, published in the journal Nature on Aug. 29, describes specimens that researchers say may help reveal how mammals evolved a different approach to reproduction than their ancestors, which produced large numbers of offspring.

"These babies are from a really important point in the evolutionary tree," said Eva Hoffman, who led research on the fossil as a graduate student at the UT Jackson School of Geosciences. "They had a lot of features similar to modern mammals, features that are relevant in understanding mammalian evolution."

Hoffman co-authored the study with her graduate adviser, Jackson School Professor Timothy Rowe.

The mammal relative belonged to an extinct species of beagle-size plant-eaters called Kayentatherium wellesi that lived alongside dinosaurs about 185 million years ago. Like mammals, Kayentatherium probably had hair.

When Rowe collected the fossil more than 18 years ago from a rock formation in Arizona, he thought that he was bringing a single specimen back with him. He had no idea about the dozens of babies it contained.

Sebastian Egberts, a former graduate student and fossil preparator at the Jackson School, spotted the first sign of the babies years later when a grain-sized speck of tooth enamel caught his eye in 2009 as he was unpacking the fossil.

"It didn't look like a pointy fish tooth or a small tooth from a primitive reptile," said Egberts, who is now an instructor of anatomy at the Philadelphia College of Osteopathic Medicine. "It looked more like a molariform tooth (molar-like tooth) -- and that got me very excited."

A CT scan of the fossil revealed a handful of bones inside the rock. However, it took advances in CT-imaging technology during the next 18 years, the expertise of technicians at UT Austin's High-Resolution X-ray Computed Tomography Facility, and extensive digital processing by Hoffman to reveal the rest of the babies -- not only jaws and teeth, but complete skulls and partial skeletons.

The 3D visualizations Hoffman produced allowed her to conduct an in-depth analysis of the fossil that verified that the tiny bones belonged to babies and were the same species as the adult. Her analysis also revealed that the skulls of the babies were like scaled-down replicas of the adult, with skulls a tenth the size but otherwise proportional. This finding is in contrast to mammals, which have babies that are born with shortened faces and bulbous heads to account for big brains.

The brain is an energy-intensive organ, and pregnancy -- not to mention childrearing -- is an energy-intensive process. The discovery that Kayentatherium had a tiny brain and many babies, despite otherwise having much in common with mammals, suggests that a critical step in the evolution of mammals was trading big litters for big brains, and that this step happened later in mammalian evolution.

"Just a few million years later, in mammals, they unquestionably had big brains, and they unquestionably had a small litter size," Rowe said.

The mammalian approach to reproduction directly relates to human development -- including the development of our own brains. By looking back at our early mammalian ancestors, humans can learn more about the evolutionary process that helped shape who we are as a species, Rowe said.

"There are additional deep stories on the evolution of development, and the evolution of mammalian intelligence and behavior and physiology that can be squeezed out of a remarkable fossil like this now that we have the technology to study it," he said.

https://www.sciencedaily.com/releases/2018/08/180829133422.htm

New Proof of Higgs Boson

In a finding that caps years of exploration into the tiny particle known as the Higgs boson, researchers have traced the fifth and most prominent way that the particle decays into other particles. The discovery gives researchers a new pathway by which to study the physical laws that govern the universe.

By Catherine Zandonella

August 28, 2018 -- Physicists at Princeton University led one of the two main teams that today announced the detection of the Higgs particle via its decay into two particles called bottom quarks. This pathway is the last to be detected of the five main signature pathways that can identify the Higgs particle.

“We found it exactly where we expected to find it and now we can use this new pathway to study the Higgs’ properties,” said James Olsen, professor of physics and leader of the team at Princeton. “This has been a truly collaborative effort from the beginning and it is exciting to see the amplification of effort that comes from people working together.”

Long-sought because it confirms theories about the nature of matter, the Higgs particle exists only fleetingly before transforming into other, so-called “daughter” particles. Because the boson lasts only for about one septillionth of a second, researchers use the particle’s offspring as evidence of its existence.

These daughter particles are scattered among the shower of particles created from the collision of two protons at the Large Hadron Collider at the European Organization for Nuclear Research (CERN). The Higgs particle was observed for the first time in 2012 through three of the other modes of decay.

Of these lineages or decay patterns, the decay into two bottom quarks occurs most often, making up about 60 percent of the decay events from the Higgs, according to Olsen.

But at the LHC, the bottom-quark pattern is the hardest to trace back definitively to the Higgs because many other particles can also give off bottom quarks.

Quarks are tiny constituents of protons, which themselves are some of the building blocks of atoms. The bottom quark is one of the six types of quarks that make up the menagerie of particles in the “standard model” that explains matter and their interactions.

Discerning which bottom quarks came from the Higgs versus other particles has been the main challenge facing the LHC’s two Higgs detectors, the Compact Muon Solenoid (CMS) with which Olsen works, and its companion, ATLAS. The detectors operate independently and are run by separate teams of scientists.

Once produced, these bottom quarks split into jets of particles, making them hard to trace back to the original parent particles. Because of this background noise, the researchers required more data than was needed for the other pathways to be sure of their finding.

Both detectors are adept at spotting particles such as electrons, photons and muons, but are more challenged by quarks. The quarks due to their nature are not observed as free particles. Instead they are bound and appear as other particles such as mesons and baryons or decay quickly.

“It is a messy business because you have to collect all of those jets and measure their properties to calculate the mass of the object that decayed into the jets,” Olsen said.

The two detectors are massive, complex structures that sit at the end of the LHC tunnel where protons are accelerated and smashed together at high energy levels. The structures contain layers of smaller detectors arranged like layers of an onion.

The devices detect particles at each layer of the onion to reconstruct their paths. This allows researchers to trace the path of a particle back to its source in a manner analogous to following the trail of a firework’s light back to the place where the first burst occurred. By following many of these paths, the researchers can identify where and when the Higgs first formed in the proton-proton collision.

“The Higgs-to-bottom-quark decay is important because it is the most frequent decay, so a precise measurement of its rate tells us a lot about the nature of this particle,” said Christopher Palmer, an associate research scholar at Princeton, who describes the work in this video. 

Additional Princeton researchers on the team included physics graduate student Stephane Cooperstein and undergraduate Jan Offerman, Class of 2018. The team also included collaborators at the University of Florida and Fermilab, as well as groups from Italy, Switzerland and Germany.

The main challenge in detecting the bottom-quark decay mode was the amount of background bottom quarks produced by non-Higgs events. In addition to gathering more data from collisions, the researchers searched for a distinct way that the Higgs gave rise to the bottom quarks.

Olsen began working on this challenge 10 years ago, before the LHC had switched on and when physicists were running simulations on computers. Around that time, Olsen learned about a theoretical study showing that it is possible to find bottom quarks created from the Higgs recoiling off another particle, such as a Z boson or a W boson.

“It was an idea that nobody had before, to search for it in that channel, and the only question was whether it was possible experimentally and whether it really would pay off,” Olsen said.

Olsen said it is exciting to see the work come to fruition. “This is a very satisfying moment.”

Link (includes animated diagram):  https://www.princeton.edu/news/2018/08/28/higgs-particles-favorite-daughter-comes-home

Two New Fatty Acids

Recently discovered: two new fatty acids in the oil of the Chinese violet cress, a plant native to central China.
By Scott Schrage, University of Nebraska

August 27, 2018 -- Decades after scientists discovered hundreds of different fatty acids in vegetable oils, two that had managed to elude detection have finally revealed themselves to a team led by the University of Nebraska-Lincoln and Huazhong Agricultural University in China.

Named for the sites of the two leading institutions, Nebraskanic acid and Wuhanic acid make up nearly half of the seed oil found in the Chinese violet cress, a flowering plant native to central China.

According to the research team, the discovery may be the first of its kind since the 1960s and 1970s, when biochemists identified troves of new fatty acids in various vegetable oils.

“People thought maybe they’d found everything there was to find,” said Nebraska’s Ed Cahoon, a George Holmes University Professor of biochemistry who co-authored an Aug. 27 study on the discovery in the journal Nature Plants. “It’s been at least several decades since somebody has discovered a new component of vegetable oil like this.”

Fatty acids represent the primary components of vegetable oils, which are best known for their role in the kitchen but have also found use in biodiesel fuels, lubricants and other industrial applications. The structure of the fatty acids housed within an oil help dictate both its health effects and industrial merits.

Most off-the-shelf vegetable oils, such as canola or soybean oil, contain the same five fatty acids. Those conventional fatty acids all contain either 16 or 18 carbon atoms and feature similar molecular structures. By contrast, Nebraskanic and Wuhanic rank among a class of “unusual” fatty acids that contain fewer or more carbon atoms — both have 24 — and uncommon molecular branches that stem from those carbons.

Whether conventional or unusual, all known fatty acids generally obey the same instruction manual: They add two carbon atoms at the end of a four-step biochemical cycle, then continue doing so until assembly is complete. But the Nebraskanic and Wuhanic acids seem to go off-book, Cahoon said, in a way rarely if ever seen outside of certain bacteria.

Both acids appear to follow the traditional script until adding their 10th pair of carbon atoms, Cahoon said. After reaching that milestone, though, the acids appear to skip the last two steps of the four-step cycle, twice cutting short the routine to accelerate the addition of the 11th and 12th carbon pairs. The process also leaves behind an oxygen-hydrogen branch, or hydroxyl group, in the fatty acid chain.

 “We sort of had an idea of what the biochemical pathway might be, but it was completely different than what’s in the biochemistry textbooks,” Cahoon said. “These fatty acids also seem to be stored in the violet cress seeds in a way that we haven’t quite seen before for other vegetable oils.

“We believe that the fatty acids are linked to one another through the hydroxyl groups to form a complex matrix of fatty acids, which is quite different from how fatty acids are arranged in a typical vegetable oil.”

That unique assembly and structure could account for the corresponding oil’s superior performance as a lubricant, which was tested at the University of North Texas. Compared with castor oil, the violet cress oil reduced friction between steel surfaces by 20 percent at 77 degrees Fahrenheit and by about 300 percent at 212 degrees Fahrenheit.

“When we saw the long-chain molecules and their arrangement, we knew the oil found in Chinese violet cress seeds would make an excellent lubricant,” said Diana Berman, assistant professor of materials science and engineering at North Texas. “This oil doesn’t just have the potential to supplement or replace petroleum-based oil; it can also replace synthetics. It is a renewable solution to a limited-resource problem.”

Cahoon said the team intends to further investigate how enzymes drive assembly of the fatty acids. Better understanding their architecture could also yield practical benefits, he said.

“We think that if we can figure out exactly how all these fatty acids are connected to one another, then we can maybe design ways to make better lubricants,” Cahoon said. “Nature can guide us.”

The “serendipitous” discovery of Nebraskanic and Wuhanic acid began in China, where Chunyu Zhang and his colleagues at Huazhong Agricultural University noticed a strange reading in a chemical analysis of the violet cress oil.

Zhang’s team was using an analytical technique known as thin-layer chromatography. The technique involves depositing a sample of liquid onto a plate, then adding a solvent and forcing the resulting solution up the plate via capillary action – a physical force that allows liquids to move against gravity in confined spaces. Different components of the solution climb the plate at different speeds, creating distinct bands that offer insights into the original sample’s chemical makeup.

To Zhang’s surprise, one of those bands seemed to have abandoned its typical perch higher up the plate for a spot farther down when the oil was deposited on a certain material. Zhang decided to consult his colleague Cahoon for a second opinion.

“He’s showing me a scan of this chromatography plate and this band,” Cahoon said. “I’d never seen anything like it. He gave me some seeds and said, ‘Let’s figure out what this is.’ That’s how the whole project started. It was very much a fluke that this was even found.”

After late nights spent confirming the anomaly and tracing its origins, the researchers tapped the expertise of Robert Minto and Alicen Teitgen at Indiana University-Purdue University Indianapolis, who spent a year helping to characterize the structures of the two fatty acids.

The team also managed to pinpoint two genes that, when activated, help kick-start production of the fatty acids. That knowledge could inform efforts to ramp up production of the oil, and its performance-enhancing fatty acids, to an industrial scale.

“With breeding and bringing in other germplasm, maybe we can make this plant into an industrial oilseed crop,” Cahoon said. “Right now, the yield is less than half that of canola, but canola’s been intensively bred for more than 50 years. It’s a great crop already.”

The researchers authored the Nature Plants study with Juan Ling, Wei Zhang and Zaiyun Li of Huazhong Agricultural University; senior research associate Xiangjun Li and postdoctoral researcher Lucas Busta, both of Nebraska’s Center for Plant Science Innovation; Rebecca Cahoon, research manager in biochemistry at Nebraska; along with Asghar Shirani and Kent Chapman from the University of North Texas.

https://news.unl.edu/newsrooms/today/article/international-team-makes-rare-discovery-of-new-fatty-acids/

 

Disorders Drive Brain Aging

Largest Brain Study of 62,454 Scans Identifies Drivers of Brain Aging
Schizophrenia, cannabis use, and alcohol abuse are just several disorders that are related to accelerated brain aging

August 21, 2018 -- In the largest known brain imaging study, scientists from Amen Clinics (Costa Mesa, CA), Google, John's Hopkins University, University of California, Los Angeles and the University of California, San Francisco evaluated 62,454 brain SPECT (single photon emission computed tomography) scans of more than 30,000 individuals from 9 months old to 105 years of age to investigate factors that accelerate brain aging. SPECT tomography) evaluates regional cerebral blood flow in the brain that is reduced in various disorders.

Lead author, psychiatrist Daniel G. Amen, MD, founder of Amen Clinics, commented, "Based on one of the largest brain imaging studies ever done, we can now track common disorders and behaviors that prematurely age the brain. Better treatment of these disorders can slow or even halt the process of brain aging. The cannabis abuse finding was especially important, as our culture is starting to see marijuana as an innocuous substance. This study should give us pause about it."

The current study used brain SPECT imaging to determine aging trajectories in the brain and which common brain disorders predict abnormally accelerated aging. It examined these functional neuroimaging scans from a large multi-site psychiatric clinic from patients who had many different psychiatric disorders, including bipolar disorder, schizophrenia and attention deficit hyperactivity disorder (ADHD).

Researchers studied 128 brain regions to predict the chronological age of the patient. Older age predicted from the scan compared to the actual chronological age was interpreted as accelerated aging. The study found that a number of brain disorders and behaviors predicted accelerated aging, especially schizophrenia, which showed an average of 4 years of premature aging, cannabis abuse (2.8 years of accelerated aging), bipolar disorder (1.6 years accelerated aging), ADHD (1.4 years accelerated aging) and alcohol abuse (0.6 years accelerated aging). Interestingly, the researchers did not observe accelerated aging in depression and aging, which they hypothesize may be due to different types of brain patterns for these disorders.

Commenting on the study, George Perry, PhD, Chief Scientist at the Brain Health Consortium from the University of Texas at San Antonio, said, "This is one of the first population-based imaging studies, and these large studies are essential to answer how to maintain brain structure and function during aging. The effect of modifiable and non-modifiable factors of brain aging will further guide advice to maintain cognitive function."

Co-investigator Sachit Egan, Google Inc. (Mountain View, CA), said, "This paper represents an important step forward in our understanding of how the brain operates throughout the lifespan. The results indicate that we can predict an individual's age based on patterns of cerebral blood flow. Additionally, groundwork has been laid to further explore how common psychiatric disorders can influence healthy patterns of cerebral blood flow."

• From: IOS Press. "Largest brain study of 62,454 scans identifies drivers of brain aging: Schizophrenia, cannabis use, and alcohol abuse are just several disorders that are related to accelerated brain aging." ScienceDaily. ScienceDaily, 21 August 2018

https://www.sciencedaily.com/releases/2018/08/180821112010.htm

Playwright Neil Simon Dies

Marvin Neil Simon (July 4, 1927 – August 26, 2018) was an American playwright, screenwriter and author. He wrote more than 30 plays and nearly the same number of movie screenplays, mostly adaptations of his plays. He received more combined Oscar and Tony nominations than any other writer.

                                                              Neil Simon in 1974

Simon grew up in New York City during the Great Depression, with his parents' financial hardships affecting their marriage, giving him a mostly unhappy and unstable childhood. He often took refuge in movie theaters where he enjoyed watching the early comedians like Charlie Chaplin. After a few years in the Army Air Force Reserve, and after graduating from high school, he began writing comedy scripts for radio and some popular early television shows. Among them were Sid Caesar's Your Show of Shows from 1950 (where he worked alongside other young writers including Carl Reiner, Mel Brooks and Selma Diamond), and The Phil Silvers Show, which ran from 1955 to 1959.

He began writing his own plays beginning with Come Blow Your Horn (1961), which took him three years to complete and ran for 678 performances on Broadway. It was followed by two more successful plays, Barefoot in the Park (1963) and The Odd Couple (1965), for which he won a Tony Award. It made him a national celebrity and "the hottest new playwright on Broadway." During the 1960s to 1980s, he wrote both original screenplays and stage plays, with some films actually based on his plays. His style ranged from romantic comedy to farce to more serious dramatic comedy. Overall, he has garnered 17 Tony nominations and won three. During one season, he had four successful plays running on Broadway at the same time, and in 1983 became the only living playwright to have a New York theatre, the Neil Simon Theatre, named in his honor.

Critical Response

For most of his career Simon's work has received mixed reviews, with many critics admiring his comedy skills, much of it a blend of "humor and pathos". Other critics were less complimentary, noting that much of his dramatic structure was weak and sometimes relied too heavily on gags and one-liners. As a result, notes Kopince, "literary scholars had generally ignored Simon's early work, regarding him as a commercially successful playwright rather than a serious dramatist." Clive Barnes, theater critic for The New York Times, wrote that like his British counterpart Noël Coward, Simon was "destined to spend most of his career underestimated", but nonetheless very "popular".

This attitude changed after 1991, when he won a Pulitzer Prize for drama with Lost in Yonkers. McGovern writes that "seldom has even the most astute critic recognized what depths really exist in the plays of Neil Simon." Although, when Lost in Yonkers was considered by the Pulitzer Advisory Board, board member Douglas Watt noted that it was the only play nominated by all five jury members, and that they judged it "a mature work by an enduring (and often undervalued) American playwright."

McGovern compares Simon with noted earlier playwrights, including Ben Jonson, Molière, and George Bernard Shaw, pointing out that those playwrights had "successfully raised fundamental and sometimes tragic issues of universal and therefore enduring interest without eschewing the comic mode." She concludes, "It is my firm conviction that Neil Simon should be considered a member of this company ... an invitation long overdue." McGovern attempts to explain the response of many critics:

Above all, his plays which may appear simple to those who never look beyond the fact that they are amusing are, in fact, frequently more perceptive and revealing of the human condition than many plays labeled complex dramas.

Similarly, literary critic Robert Johnson explains that Simon's plays have given us a "rich variety of entertaining, memorable characters" who portray the human experience, often with serious themes. Although his characters are "more lifelike, more complicated and more interesting" than most of the characters audiences see on stage, Simon has "not received as much critical attention as he deserves." Lawrence Grobel, in fact, calls him "the Shakespeare of his time", and possibly the "most successful playwright in history." He states:

Simon towers like a Colossus over the American Theater. When Neil Simon's time comes to be judged among successful playwrights of the twentieth century, he will definitely be first among equals. No other playwright in history has had the run he has: fifteen "Best Plays" of their season.

Broadway critic Walter Kerr tries to rationalize why Simon's work has been underrated:

Because Americans have always tended to underrate writers who make them laugh, Neil Simon's accomplishment have not gained as much serious critical praise as they deserve. His best comedies contain not only a host of funny lines, but numerous memorable characters and an incisively dramatized set of beliefs that are not without merit. Simon is, in fact, one of the finest writers of comedy in American literary history.

https://en.wikipedia.org/wiki/Neil_Simon

Pythons in South Florida

Genetic Analysis of Florida's Invasive
Pythons Reveals a Tangled Family Tree

From the U.S. Geological Survey –- August 25, 2018 -- A new genetic analysis of invasive pythons captured across South Florida finds the big constrictors are closely related to one another. In fact, most of them are genetically related as first or second cousins, according to a study by wildlife genetics experts at the U.S. Geological Survey.

The study also found that at least a few of the snakes in the invasive South Florida population are not 100 percent Burmese pythons. Instead, the genetic evidence shows at least 13 snakes out of about 400 studied are a cross between two separate species: Burmese pythons, which mostly inhabit wetlands, and Indian pythons, which prefer higher ground. The interbreeding between Burmese and Indian pythons probably took place before the animals became established in the South Florida environment, and may have given them greater adaptability in their new habitats.

The South Florida pythons spring from a tangled family tree, with consequences for the species' future spread that are hard to predict, the USGS scientists said.

"The snakes in South Florida are physically identifiable as Burmese pythons, but genetically, there seems to be a different, more complicated story," said Margaret Hunter, a USGS research geneticist and lead author on the study published in the journal Ecology and Evolution.

Burmese pythons have been reproducing in the Everglades since the 1980s, and have caused important environmental changes including the decline of small-mammal populations in South Florida.

The researchers analyzed tail tissue from about 400 Burmese pythons captured across a wide area, from southwest Florida and the Big Cypress National Preserve to the Everglades, southeast Miami-Dade County and the Florida Keys, between 2001 and 2012.

The researchers looked at nuclear DNA, which contains genetic material from both parents, to determine how much each animal had in common with others in the population. To express family relationships in statistical terms, they used a common type of calculation known as a relatedness value. For all snakes in the study, the average relatedness value was about midway between first and second cousins. That close kinship means the population as a whole is experiencing inbreeding, the researchers concluded.

When the researchers tested genetic material from a different part of the snakes' cells-mitochondrial DNA, inherited solely from the mother-they were surprised to find genetic signatures from the Indian python in 13 snakes.

Sometimes interbreeding between related species "can lead to hybrid vigor, that is, the best traits of two species are passed onto their offspring," Hunter said. "Hybrid vigor can potentially lead to a better ability to adapt to environmental stressors and changes. In an invasive population like the Burmese pythons in South Florida, this could result in a broader or more rapid distribution."

In the wild, related species typically avoid interbreeding by using different habitats. In their native Asia, Burmese pythons prefer wet habitats, while Indian pythons tend to stick to drier ones. In previous studies, scientists have observed South Florida's Burmese pythons in both wet and dry habitat types.

"Our ability to detect Burmese pythons in the Greater Everglades has been limited by their effective camouflage and secretive behavior," said Kristen Hart, a USGS research ecologist and a co-author on the study. "By using genetic tools and techniques and continuing to monitor their movement patterns, we have been able to gain a better understanding of their habitat preferences and resource use. The new information in this study will help scientists and wildlife managers better understand these invasive predators' capacity to adapt to new environments."

                           https://www.sciencedaily.com/releases/2018/08/180825132319.htm

Better Lithium Oxygen Battery

Chemists Make Breakthrough on Road to Creating
a Rechargeable Lithium-Oxygen Battery

Waterloo, Ontario – August 23, 2018 -- Chemists from the University of Waterloo have successfully resolved two of the most challenging issues surrounding lithium-oxygen batteries, and in the process created a working battery with near 100 per cent coulombic efficiency.

The new work, which appears this week in Science, proves that four-electron conversion for lithium-oxygen electrochemistry is highly reversible. The team is the first to achieve four-electron conversion, which doubles the electron storage of lithium-oxygen, also known as lithium-air, batteries.

“There are limitations based on thermodynamics,” said Linda Nazar, Canada Research Chair of Solid State Energy Materials and senior author on the project. “Nevertheless, our work has addressed fundamental issues that people have been trying to resolve for a long time.”

The high theoretical-energy density of lithium-oxygen (Li-O₂) batteries and their relatively light weight have made them the Holy Grail of rechargeable battery systems. But long-standing issues with the battery’s chemistry and stability have kept them a purely academic curiosity.

Two of the more serious issues involve the intermediate of the cell chemistry (superoxide, LiO₂) and the peroxide product (Li₂O₂) reacting with the porous carbon cathode, degrading the cell from within. In addition, the superoxide consumes the organic electrolyte in the process, which greatly limits the cycle life.

Nazar and her colleagues switched the organic electrolyte to a more stable inorganic molten salt and the porous carbon cathode to a bifunctional metal oxide catalyst. Then by operating the battery at 150 C, they found that the more stable product Li₂O is formed instead of Li₂O₂. This results in a highly reversible Li-oxygen battery with coulombic efficiency approaching 100 per cent.

By storing O₂ as lithium oxide (Li₂O) instead of lithium peroxide (Li₂O₂), the battery not only maintained excellent charging characteristics, it achieved the maximum four-electron transfer in the system, thereby increasing the theoretical energy storage by 50 per cent.

“By swapping out the electrolyte and the electrode host and raising the temperature, we show the system performs remarkably well,” said Nazar, who is also a University Research Professor in the Department of Chemistry at Waterloo.

The lead author on the study is Chun Xia, a postdoctoral fellow, and co-author is Chun Yuen Kwok, a PhD student, both in Nazar’s lab.

The Natural Sciences and Engineering Research Council of Canada in part funded the project through their Discovery Grants and Canada Research Chair programs, along with the U.S. Department of Energy’s Joint Center for Energy Storage Research.

https://uwaterloo.ca/news/news/chemists-make-breakthrough-road-creating-rechargeable

Progress Toward Nuclear Fusion

Steady as she goes: Scientists tame damaging plasma instabilities and pave the way for efficient fusion on Earth
By John Greewald

Princeton, NJ, August 21, 2018 -- Before scientists can capture and recreate the fusion process that powers the sun and stars to produce virtually limitless energy on Earth, they must first learn to control the hot plasma gas that fuels fusion reactions. In a set of recent experiments, scientists have tamed a plasma instability in a way that could lead to the efficient and steady state operation of ITER, the international experiment under construction in France to demonstrate the feasibility of fusion power. Such continuous operation will be essential for future fusion devices. 

Fusion powers the sun and stars by fusing light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei — to produce massive amounts of energy. Scientists are seeking to replicate fusion on Earth for a virtually inexhaustible supply of electricity-generating power. 

The most recent findings, developed by a team of researchers led by physicist Raffi Nazikian of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and Craig Petty of General Atomics, stem from experiments conducted on the DIII-D National Fusion Facility operated by General Atomics for the DOE in San Diego. The results build on earlier work led by DIII-D scientists that demonstrated the conditions needed for steady-state operation of the core of ITER plasmas and established techniques to control these plasma instabilities.   

The new research targets instabilities called Edge Localized Modes (ELMs) that develop at the periphery of fusion plasmas. Such instabilities can cause periodic heat bursts that can damage plasma-facing components in a tokamak. “In these results we observe the suppression of large ELMs, leaving small benign ELMs in plasmas that overlap with the conditions required for steady-state ITER operation,” said Nazikian, lead author of a scientific paper in IAEA’s Nuclear Fusion journal that lays out the findings. “These new experiments are a great example of successfully combining two separate advances, in this case 100 percent current drive in the plasma core and large ELM suppression in the edge, in an efficient and effective manner” said Petty, lead author of a prior Nuclear Fusion paper on the DIII-D findings relevant to the steady state core of the ITER plasma.

To keep large ELMs from occurring, researchers produce small magnetic ripples known as resonant magnetic perturbations (RMPs) that distort the smooth doughnut shape of tokamak plasmas. In the recent experiments, the scientists found that increasing the overall pressure of the plasma makes the plasma far more responsive to the ripples to better control ELMs and produce the conditions needed for steady-state ITER operation. 

The higher pressure also increases a self-generated current that forms inside tokamak plasmas. This can be combined with particle beams and microwaves to drive and sustain the plasma current indefinitely in a so-called steady state. These higher self-generated currents make this process more efficient, and thus a fusion power plant more attractive.

When researchers projected the recent DIII-D results to ITER, they found that the higher plasma pressure and bootstrap current, together with additional sources of current from particle beams and microwaves, could create a fully sustainable steady-state regime that generates four-to-five times more power than it will take to heat the plasma and drive the current. Support for this work comes from the DOE Office of Science (FES) and the General Atomics Postdoctoral Research Participation Program administered by Oak Ridge Associated Universities (ORAU).

Going forward, physicists seek to create a greater percentage of bootstrap current to increase the fusion power gain and reduce the additional power needed to drive current. These DIII-D experiments produced about 30 percent self-driven current, although the bootstrap current fraction are projected to increase in ITER as its higher field means its ions collide less often, enabling current to be driven more easily. 

“What we are currently working on in DIII-D is to develop the basis for fully steady-state high pressure plasma for ITER and beyond,” Nazikian said. “A central goal of the DIII-D program now is to identify ways in which high-pressure plasmas can drive most of the current required for steady-state reactors. We are undertaking major upgrades to the facility to meet this goal while exploring regimes that are free of dangerous ELMs.”

https://www.pppl.gov/news/2018/08/steady-she-goes-scientists-tame-damaging-plasma-instabilities-and-pave-way-efficient

U.S. in Debt "Danger Zone"

Study shows harmful interaction of public, private debt
By Jeff Grabmeier, Ohio State News

August 21, 2018 -- The interaction of public and private debt in the United States reduced economic growth about 0.43 percentage points per year between 2009 and 2014, a new study suggests.

In addition, growth declined an additional 0.40 percent due solely to high levels of private debt, taking into account public debt.

Overall, the results suggest debt dragged U.S. growth down by at least 0.83 percentage points in this time period.

“The effect that debt is having on our economic growth is much larger than we expected. We were surprised,” said Mehmet Caner, co-author of the study and professor of economics at The Ohio State University.

The nation’s GDP (Gross Domestic Product) grew 4.1 percent in the most recent quarter, but Caner said growth would have been even larger without the current level of debt.

“We should be worried,” he said.

Most economists have examined how one type of debt – either public or private – affects economic growth. But this study is one of the first to show that the interaction of the two should be a real concern, Caner said.

“We were able to quantify the effects of this debt interaction and it is kind of scary.”

Caner and his colleagues used data from 29 advanced countries (members of the Organisation for Economic Co-operation and Development, or OECD) from 1995 to 2014 to see how debt was related to economic growth. They found that when both public and private debt were relatively low, their interaction could stimulate economic growth.

Even when debt rises, increases in public debt can be offset by decreases in private debt, or vice versa. But if they are both at relatively high levels and increasing at the same time, their interaction can be particularly harmful for growth, results showed.

The study found that the interaction of public and private debt reaches a “danger zone” when it goes above 100 and 137 percent of the nation’s GDP for public and private debt respectively.

The researchers calculated that 12 of the 29 countries studied – including the United States – were in this danger zone during the time of the study. The U.S. public-private debt interaction was at 203 percent in the 2009-2014 period.

If debt was reducing U.S. growth by around 1 percentage point a year – as this study suggests – that may explain a large portion of why growth went from 3.3 percent per year before the Great Recession (2007-2009) to about 2.2 percent since the recession.

“Since 2014, both public and private debt ratios in the U.S. have increased, indicating that debt has become an even greater obstacle to growth,” Caner said.

Not all kinds of private debt had the same effects, the study found. Results showed that household debt had a much more negative effect than corporate debt.

The reason may be that corporate debt generally goes to more productive uses compared to household spending, such as investments in plants and machinery.

Why is the interaction between private and public debt important for economic growth?

Caner said one reason might be that the government guarantees much private debt, including mortgages and school loans.

“Greater private default often means greater public debt,” he said.

These results suggest that Congress should work to control public debt, as many commentators and political groups have suggested, Caner said.

“The other implication is that agencies responsible for regulating private debt should not ignore the interaction between public and private debt, especially mortgage debt,” he said.

Caner conducted the study with Michael Fan of Xiamen University in China and Thomas Grennes of North Carolina State University.

                        https://news.osu.edu/how-the-united-states-landed-in-a-debt-danger-zone/

Modern Martyr Alfons Tracki

Blessed Alfons Tracki (2 December 1896 – 18 July 1946) was an Albanian Catholic priest of German origin, who died as a Christian martyr as a result of the religious persecution by the regime of Enver Hoxha in communist Albania.

                                                              Alfons Tracki in 1930

Life and Martyrdom

Tracki was born in Bleischwitz, German Empire (now Poland) on 2 December 1896. The son of Josef Tracki and his wife Martha, née Schramm, Alfons grew up in a village in Upper Silesia. When he attended school, he had contact with the Christian School Brothers. He requested to be admitted to the community at their provincial school in Vienna at age 14. He was accepted, and after a novitiate of two years became a member on 16 August 1913, with the religious name Gebhard. He was sent to Albania before World War I and taught at the Xaverian College in Shkodër. With the outbreak of the war, he returned to his home village. He served in the military for two years. He also completed his vows during the war. After the war, he returned to Shkodër, where he studied philosophy and theology. He was ordained as a priest on 14 June 1925 by Lazër Mjeda, the archbishop there. He exercised his ministry in Northern Albania, teaching in the schools and organizing sports for the youth.

Tracki became chaplain at the St. Stephen's Cathedral in Shkodër. He founded a Catholic youth organisation, Viribus unitis ("With joined powers"). After his time as chaplain, he became the parish priest of Velipoja. Tracki is remembered, in Zef Pllumi's memoirs Live to tell, as a good priest and crucial in the upbringing of other priests, such as would-be martyr Ejëll Deda (sq). Further, he was heavily involved in the eradication of the Gjakmarrja (Northern Albanian blood feuds), by offering a Christian solution of peace to them.

Communist partisans under Enver Hoxha fought against the Italian and German occupying forces. After the Albanian Communist Party came to power, conspirators with the former rulers were prosecuted, which included Catholics in general. Pjetër Arbnori wrote that Tracki joined a group of anti-communist Freischärler in the mountains. When Tracki administered the Extreme Unction to a fatally wounded soldier, he was arrested. He was in a prison in Shkodër from 13 February 1946, and was sentenced to death on 17 July for performing an illegal priestly act. He was executed on 18 July 1946. According to witnesses, his last words were: "... I do not regret dying, as long as I'm dying together with my brothers, and I have contributed, as much as they have, for your own good, and for the religion of Christ."

Beatified on 5 November 2016 with the other martyrs of Albania, Tracki is venerated as a martyr by the Catholic Church and commemorated with the other martyrs of Albania on 18 July, the date of his execution.

https://en.wikipedia.org/wiki/Alfons_Tracki

Alloy Most Resistant to Wear

Most Wear-Resistant Metal Alloy in the World Engineered at Sandia National Laboratories

ALBUQUERQUE, N.M. —- August 16, 2018 -- If you’re ever unlucky enough to have a car with metal tires, you might consider a set made from a new alloy engineered at Sandia National Laboratories. You could skid — not drive, skid — around the Earth’s equator 500 times before wearing out the tread.

Sandia’s materials science team has engineered a platinum-gold alloy believed to be the most wear-resistant metal in the world. It’s 100 times more durable than high-strength steel, making it the first alloy, or combination of metals, in the same class as diamond and sapphire, nature’s most wear-resistant materials. Sandia’s team recently reported their findings in Advanced Materials. “We showed there’s a fundamental change you can make to some alloys that will impart this tremendous increase in performance over a broad range of real, practical metals,” said materials scientist Nic Argibay, an author on the paper.

Although metals are typically thought of as strong, when they repeatedly rub against other metals, like in an engine, they wear down, deform and corrode unless they have a protective barrier, like additives in motor oil.

In electronics, moving metal-to-metal contacts receive similar protections with outer layers of gold or other precious metal alloys. But these coatings are expensive. And eventually they wear out, too, as connections press and slide across each other day after day, year after year, sometimes millions, even billions of times. These effects are exacerbated the smaller the connections are, because the less material you start with, the less wear and tear a connection can endure before it no longer works.

With Sandia’s platinum-gold coating, only a single layer of atoms would be lost after a mile of skidding on the hypothetical tires. The ultradurable coating could save the electronics industry more than $100 million a year in materials alone, Argibay says, and make electronics of all sizes and across many industries more cost-effective, long-lasting and dependable — from aerospace systems and wind turbines to microelectronics for cell phones and radar systems.

“These wear-resistant materials could potentially provide reliability benefits for a range of devices we have explored,” said Chris Nordquist, a Sandia engineer not involved in the study. “The opportunities for integration and improvement would be device-specific, but this material would provide another tool for addressing current reliability limitations of metal microelectronic components.”

New metal puts an old theory to rest

You might be wondering how metallurgists for thousands of years somehow missed this. In truth, the combination of 90 percent platinum with 10 percent gold isn’t new at all.

But the engineering is new. Argibay and coauthor Michael Chandross masterminded the design and the new 21st century wisdom behind it. Conventional wisdom says a metal’s ability to withstand friction is based on how hard it is. The Sandia team proposed a new theory that says wear is related to how metals react to heat, not their hardness, and they handpicked metals, proportions and a fabrication process that could prove their theory.

“Many traditional alloys were developed to increase the strength of a material by reducing grain size,” said John Curry, a postdoctoral appointee at Sandia and first author on the paper. “Even still, in the presence of extreme stresses and temperatures many alloys will coarsen or soften, especially under fatigue. We saw that with our platinum-gold alloy the mechanical and thermal stability is excellent, and we did not see much change to the microstructure over immensely long periods of cyclic stress during sliding.”

Now they have proof they can hold in their hands. It looks and feels like ordinary platinum, silver-white and a little heavier than pure gold. Most important, it’s no harder than other platinum-gold alloys, but it’s much better at resisting heat and a hundred times more wear resistant.

The team’s approach is a modern one that depended on computational tools. Argibay and Chandross’ theory arose from simulations that calculated how individual atoms were affecting the large-scale properties of a material, a connection that’s rarely obvious from observations alone. Researchers in many scientific fields use computational tools to take much of the guesswork out of research and development.

“We’re getting down to fundamental atomic mechanisms and microstructure and tying all these things together to understand why you get good performance or why you get bad performance, and then engineering an alloy that gives you good performance,” Chandross said.

A slick surprise

Still, there will always be surprises in science. In a separate paper published in Carbon, the Sandia team describes the results of a remarkable accident. One day, while measuring wear on their platinum-gold, an unexpected black film started forming on top. They recognized it: diamond-like carbon, one of the world’s best man-made coatings, slick as graphite and hard as diamond. Their creation was making its own lubricant, and a good one at that.

Diamond-like carbon usually requires special conditions to manufacture, and yet the alloy synthesized it spontaneously.

“We believe the stability and inherent resistance to wear allows carbon-containing molecules from the environment to stick and degrade during sliding to ultimately form diamond-like carbon,” Curry said. “Industry has other methods of doing this, but they typically involve vacuum chambers with high temperature plasmas of carbon species. It can get very expensive.”

The phenomenon could be harnessed to further enhance the already impressive performance of the metal, and it could also potentially lead to a simpler, more cost-effective way to mass-produce premium lubricant.

                              https://share-ng.sandia.gov/news/resources/news_releases/resistant_alloy/

Metal Tags Expand Internet of Things

Metal Tags Turn Everyday Objects
into Smart, Connected Devices

San Diego, Calif., Aug. 16, 2018 -- Engineers have developed printable metal tags that could be attached to everyday objects and turn them into “smart” Internet of Things devices.

The metal tags are made from patterns of copper foil printed onto thin, flexible, paper-like substrates and are made to reflect WiFi signals. The tags work essentially like “mirrors” that reflect radio signals from a WiFi router. When a user’s finger touches these mirrors, it disturbs the reflected WiFi signals in such a way that can be remotely sensed by a WiFi receiver, like a smartphone.

The tags can be tacked onto plain objects that people touch and interact with every day, like water bottles, walls or doors. These plain objects then essentially become smart, connected devices that can signal a WiFi device whenever a user interacts with them. The tags can also be fashioned into thin keypads or smart home control panels that can be used to remotely operate WiFi-connected speakers, smart lights and other Internet of Things appliances.

“Our vision is to expand the Internet of Things to go beyond just connecting smartphones, smartwatches and other high-end devices,” said senior author Xinyu Zhang, a professor of electrical and computer engineering at the UC San Diego Jacobs School of Engineering and member of the Center for Wireless Communications at UC San Diego. “We’re developing low-cost, battery-free, chipless, printable sensors that can include everyday objects as part of the Internet of Things.”

Zhang’s team named the technology “LiveTag.” These metal tags are designed to only reflect specific signals within in the WiFi frequency range. By changing the type of material they’re made of and the pattern in which they’re printed, the researchers can redesign the tags to reflect either Bluetooth, LTE or cellular signals.

The tags have no batteries, silicon chips, or any discrete electronic components, so they require hardly any maintenance—no batteries to change, no circuits to fix.

The team presented their work at the recent USENIX Symposium on Networked Systems Design and Implementation Conference.

Smart tagging

As a proof of concept, the researchers used LiveTag to create a paper-thin music player controller complete with a play/pause button, next track button and sliding bar for tuning volume. The buttons and sliding bar each consist of at least one metal tag so touching any of them sends signals to a WiFi device. The researchers have so far only tested the LiveTag music player controller to remotely trigger a WiFi receiver, but they envision that it would be able to remotely control WiFi-connected music players or speakers when attached to a wall, couch armrest, clothes, or other ordinary surface.

The researchers also adapted LiveTag as a hydration monitor. They attached it to a plastic water bottle and showed that it could be used to track a user’s water intake by monitoring the water level in the bottle. The water inside affects the tag’s response in the same way a finger touch would—as long as the bottle is not made of metal, which would block the signal. The tag has multiple resonators that each get detuned at a specific water level. The researchers imagine that the tag could be used to deliver reminders to a user’s smartphone to prevent dehydration.

Future applications

On a broader scope, Zhang envisions using LiveTag technology to track human interaction with everyday objects. For example, LiveTag could potentially be used as an inexpensive way to assess the recovery of patients who have suffered from stroke.

“When patients return home, they could use this technology to provide data on their motor activity based on how they interact with everyday objects at home—whether they are opening or closing doors in a normal way, or if they are able to pick up bottles of water, for example. The amount, intensity and frequency of their activities could be logged and sent to their doctors to evaluate their recovery,” said Zhang. “And this can all be done in the comfort of their own homes rather than having to keep going back to the clinic for frequent motor activity testing,” he added.

Another example is tagging products at retail stores and assessing customer interest based on which products they touch. Rather than use cameras, stores could use LiveTag as an alternative that offers customers more privacy, said Zhang.

Next steps

The researchers note several limitations of the technology. LiveTag currently cannot work with a WiFi receiver further than one meter (three feet) away, so researchers are working on improving the tag sensitivity and detection range. Ultimately, the team aims to develop a way to make the tags using normal paper and ink printing, which would make them cheaper to mass produce.

http://jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=2614

Snapping Spaghetti Noodles

Mathematicians Solve Age-Old Spaghetti Mystery

Massachusetts Institute of Technology – August 13, 2018 -- If you happen to have a box of spaghetti in your pantry, try this experiment: Pull out a single spaghetti stick and hold it at both ends. Now bend it until it breaks. How many fragments did you make? If the answer is three or more, pull out another stick and try again. Can you break the noodle in two? If not, you're in very good company.

The spaghetti challenge has flummoxed even the likes of famed physicist Richard Feynman '39, who once spent a good portion of an evening breaking pasta and looking for a theoretical explanation for why the sticks refused to snap in two.

Feynman's kitchen experiment remained unresolved until 2005, when physicists from France pieced together a theory to describe the forces at work when spaghetti -- and any long, thin rod -- is bent. They found that when a stick is bent evenly from both ends, it will break near the center, where it is most curved. This initial break triggers a "snap-back" effect and a bending wave, or vibration, that further fractures the stick. Their theory, which won the 2006 Ig Nobel Prize, seemed to solve Feynman's puzzle. But a question remained: Could spaghetti ever be coerced to break in two?

The answer, according to a new MIT study, is yes -- with a twist. In a paper published this week in the Proceedings of the National Academy of Sciences, researchers report that they have found a way to break spaghetti in two, by both bending and twisting the dry noodles. They carried out experiments with hundreds of spaghetti sticks, bending and twisting them with an apparatus they built specifically for the task. The team found that if a stick is twisted past a certain critical degree, then slowly bent in half, it will, against all odds, break in two.

The researchers say the results may have applications beyond culinary curiosities, such as enhancing the understanding of crack formation and how to control fractures in other rod-like materials such as multifiber structures, engineered nanotubes, or even microtubules in cells.

"It will be interesting to see whether and how twist could similarly be used to control the fracture dynamics of two-dimensional and three-dimensional materials," says co-author Jörn Dunkel, associate professor of physical applied mathematics at MIT. "In any case, this has been a fun interdisciplinary project started and carried out by two brilliant and persistent students -- who probably don't want to see, break, or eat spaghetti for a while."

The two students are Ronald Heisser '16, now a graduate student at Cornell University, and Vishal Patil, a mathematics graduate student in Dunkel's group at MIT. Their co-authors are Norbert Stoop, instructor of mathematics at MIT, and Emmanuel Villermaux of Université Aix Marseille.

A deep dish dive

Heisser, together with project partner Edgar Gridello, originally took up the challenge of breaking spaghetti in the spring of 2015, as a final project for 18.354 (Nonlinear Dynamics: Continuum Systems), a course taught by Dunkel. They had read about Feynman's kitchen experiment, and wondered whether spaghetti could somehow be broken in two and whether this split could be controlled.

"They did some manual tests, tried various things, and came up with an idea that when he twisted the spaghetti really hard and brought the ends together, it seemed to work and it broke into two pieces," Dunkel says. "But you have to twist really strongly. And Ronald wanted to investigate more deeply."

So Heisser built a mechanical fracture device to controllably twist and bend sticks of spaghetti. Two clamps on either end of the device hold a stick of spaghetti in place. A clamp at one end can be rotated to twist the dry noodle by various degrees, while the other clamp slides toward the twisting clamp to bring the two ends of the spaghetti together, bending the stick.

Heisser and Patil used the device to bend and twist hundreds of spaghetti sticks, and recorded the entire fragmentation process with a camera, at up to a million frames per second. In the end, they found that by first twisting the spaghetti at almost 360 degrees, then slowly bringing the two clamps together to bend it, the stick snapped exactly in two. The findings were consistent across two types of spaghetti: Barilla No. 5 and Barilla No. 7, which have slightly different diameters.

Noodle twist

In parallel, Patil began to develop a mathematical model to explain how twisting can snap a stick in two. To do this, he generalized previous work by the French scientists Basile Audoly and Sebastien Neukirch, who developed the original theory to describe the "snap-back effect," in which a secondary wave caused by a stick's initial break creates additional fractures, causing spaghetti to mostly snap in three or more fragments.

Patil adapted this theory by adding the element of twisting, and looked at how twist should affect any forces and waves propagating through a stick as it is bent. From his model, he found that, if a 10-inch-long spaghetti stick is first twisted by about 270 degrees and then bent, it will snap in two, mainly due to two effects. The snap-back, in which the stick will spring back in the opposite direction from which it was bent, is weakened in the presence of twist. And, the twist-back, where the stick will essentially unwind to its original straightened configuration, releases energy from the rod, preventing additional fractures.

"Once it breaks, you still have a snap-back because the rod wants to be straight," Dunkel explains. "But it also doesn't want to be twisted."

Just as the snap-back will create a bending wave, in which the stick will wobble back and forth, the unwinding generates a "twist wave," where the stick essentially corkscrews back and forth until it comes to rest. The twist wave travels faster than the bending wave, dissipating energy so that additional critical stress accumulations, which might cause subsequent fractures, do not occur.

"That's why you never get this second break when you twist hard enough," Dunkel says.

The team found that the theoretical predictions of when a thin stick would snap in two pieces, versus three or four, matched with their experimental observations.

"Taken together, our experiments and theoretical results advance the general understanding of how twist affects fracture cascades," Dunkel says.

For now, he says the model is successful at predicting how twisting and bending will break long, thin, cylindrical rods such as spaghetti. As for other pasta types?

"Linguini is different because it's more like a ribbon," Dunkel says. "The way the model is constructed it applies to perfectly cylindrical rods. Although spaghetti isn't perfect, the theory captures its fracture behavior pretty well."

https://www.sciencedaily.com/releases/2018/08/180813160537.htm