Thursday, October 17, 2019

New Understanding of the Evolution of Cosmic Electromagnetic Fields



Next year is the 200 years anniversary of the discovery of electromagnetism by the Danish physicist H.C. Ørsted. Even 200 years after its discovery, the existence of electromagnetism still brings up new puzzles pertaining to their origin.

One such mystery is the origin of electro magnetic fields on the very largest scale in the universe.

While researchers have believed for some time that magnetic fields of femto-Gauss strength extend to the largest scales in the universe — to scales larger than the largest clusters of galaxies — it is an unresolved mystery how such magnetic fields can have been created in the early universe.

Credit: NASA/JPL-Caltech/J. Bally (Univ. of Colo.)

The very early universe

One logical possibility is that the magnetic fields were enhanced by the primordial period of inflation, which is needed also to solve the flatness and horizon problem in the standard Big-Bang model, if the magnetic fields in this period had some new non-standard interactions with the inflaton particle. The inflaton particle is responsible for driving the period of primordial inflation.

But the problem is that magnetic fields generated during inflation have been believed to quickly be washed away by the subsequent ordinary expansion of the universe making successful inflationary magnetogenesis a challenge.

Recently the researchers Takeshi Kobayashi from International Centre for Theoretical Physics in Italy and Martin S. Sloth from University of Southern Denmark (the university in the region were H.C. Ørsted was born) have shown that due to Faraday’s law of induction, the assumed evolution of electromagnetic fields after inflation is different than previously assumed if there are also strong primordial electric fields.

The work has been published in the journal Physical Review D.

“This opens a new door to our understanding of the origin of cosmic magnetic fields”, says Martin S. Sloth, professor, CP3-Origins, Center for Cosmology and Particle Physics Phenomenology, University of Southern Denmark.


Contacts and sources:
Birgitte Svennevig
University of Southern Denmark.

Citation: Early cosmological evolution of primordial electromagnetic fields. Takeshi Kobayashi, Martin S. Sloth. Physical Review D, 2019; 100 (2) DOI: 10.1103/PhysRevD.100.023524


Wednesday, October 16, 2019

A Breath Test of Opiods



A test to detect opioid drugs in exhaled breath has been developed by engineers and physicians at the University of California, Davis. A breath test could be useful in caring for chronic pain patients as well as for checking for illegal drug use.

“There are a few ways we think this could impact society,” said professor Cristina Davis, chair of the Department of Mechanical and Aerospace Engineering at UC Davis, who led the research along with Professor Michael Schivo from the UC Davis Medical Center. The work is described in a paper published in the Journal of Breath Research Oct. 3.

A table full of fentanyl and other designer drugs seized by CBP sit on display at the International Mail Facility
File:Opiod Epidemic (23882642067).jpg
Credit: U.S. Customs and Border Protection

Doctors and nurses treating chronic pain may need to monitor patients to make sure they are taking their drugs correctly, that their prescribed drugs are being metabolized properly and that they are not taking additional medications. Blood tests are the gold standard: a reliable, noninvasive test would be a useful alternative. 

Collecting droplets from breath

For the test developed by postdoctoral researcher Eva Borras, Davis and colleagues, subjects breathe normally into a specialized collection device. Droplets in breath condense and are stored in a freezer until testing. Davis’ lab uses mass spectrometry to identify compounds in the samples.

The researchers tested the technique in a small group of patients receiving infusions of pain medications including morphine and hydromorphone, or oral doses of oxycodone, at the UC Davis Medical Center. They were therefore able to compare opioid metabolites in breath with both blood samples and the doses given to patients.

“We can see both the original drug and metabolites in exhaled breath,” Davis said.

Fully validating the breath test will require more data from larger groups of patients, she said. Davis’ laboratory is working toward real-time, bedside testing.

Other authors on the paper include graduate student Andy Cheng, UC Davis forensic science program; Ted Wun, Department of Internal Medicine; Kristen Reese and Matthias Frank, Lawrence Livermore National Laboratory; and Michael Schivo, UC Davis School of Medicine and VA Northern California Health System.

Davis’ laboratory is working on a variety of applications for detecting small amounts of chemicals, especially in air and exhaled breath. Other projects include diagnosing influenza in people and citrus greening disease in fruit trees.

The work was supported by grants from the UC Davis Medical Center’s Collaborative for Diagnostic Innovation, the U.S. Department of Energy and the NIH.

Contacts and sources:
Andy Fell
UC Davis

Citation:



Accelerating Global Agricultural Productivity Growth Is Critical to Feed 10 Billion by 2050

The Global Agricultural Productivity Index tracks global progress toward the sustainable production of food, feed, fiber, and bioenergy for 10 billion people in 2050.


The 2019 Global Agricultural Productivity Report, "Productivity Growth for Sustainable Diets, and More," released today by Virginia Tech’s College of Agriculture and Life Sciences, shows agricultural productivity growth – increasing output of crops and livestock with existing or fewer inputs – is growing globally at an average annual rate of 1.63 percent.

According to the report’s Global Agricultural Productivity Index, global agricultural productivity needs to increase at an average annual rate of 1.73 percent to sustainably produce food, feed, fiber, and bioenergy for 10 billion people in 2050.

Productivity growth is strong in China and South Asia, but it is slowing in the agricultural powerhouses of North America, Europe, and Latin America.

The report calls attention to the alarmingly low levels of productivity growth in low-income countries, where there also are high rates of food insecurity, malnutrition, and rural poverty.

Agricultural productivity growth in low-income countries is rising at an average annual rate of just 1 percent. The UN Sustainable Development Goals call for doubling the productivity of the lowest-income farmers by 2030.

The GAP Report was released at the World Food Prize in Des Moines, Iowa. Speakers at the GAP Report Launch event included Tim Sands, president of Virginia Tech; Miguel Garcia Winder, undersecretary for agriculture for Mexico; Rose Mwonya, vice chancellor of the Egerton University in Kenya; and Alan Grant, dean of Virginia Tech’s College of Agriculture and Life Sciences.

The report calls for a strong focus on countries with high rates of population growth, persistent low levels of agricultural productivity, and significant shifts in consumption patterns — the primary drivers of unsustainable agricultural practices, such as converting forests to crop and rangeland.

“These productivity gaps, if they persist, will have serious ramifications for environmental sustainability, the economic vitality of the agriculture sector, and the prospects for reducing poverty, malnutrition, and obesity,” said Ann Steensland, author of the 2019 GAP Report and coordinator of the GAP Report Initiative at Virginia Tech.

The 2019 GAP Report examines the pivotal role of agricultural productivity in achieving global goals for environmental sustainability, economic development, and improved nutrition.

“Decades of research and experience tell us that by accelerating productivity growth, it is possible to improve environmental sustainability, while ensuring that consumers have access to the foods they need and want,” said Tom Thompson, associate dean and director of global programs for the Virginia Tech College of Agriculture and Life Sciences.

Productivity growth is generated by such innovations as precision agriculture technology and improved seeds and best practices for nutrient management and animal health. Attention to ecosystem services, such as pollination and erosion prevention, can increase and sustain productivity gains over time.

The GAP Report looks at the powerful combination of agricultural technology, best farm management practices, and attention to ecosystem services in supporting productivity growth, sustainability, and resilience.

Historically, productivity growth has been strongest in high-income countries, such as the U.S, with significant environmental benefits.

Due to widespread adoption of improved agricultural technologies and best farm management practices, especially in high-income countries, global agricultural output has increased by 60 percent, while global cropland has increased by just 5 percent during the past 40 years.

Between 1980 and 2015, productivity gains led to a 41 percent decrease in the amount of land used in U.S. corn production, irrigation water use declined 46 percent, greenhouse gas emissions declined 31 percent, and soil erosion declined (tons of soil loss per acre) by 58 percent.

Animal agriculture in the U.S. has experienced similar productivity gains, dramatically reducing the environmental footprint of the livestock production. According to Robin White, assistant professor of animal and poultry science at Virginia Tech, if livestock production in the U.S. was eliminated, total U.S. greenhouse gas emissions would decline by only 2.9 percent.

The Global Agricultural Productivity Index tracks global progress toward sustainably producing food, feed, fiber, and bioenergy for 10 billion people in 2050.

In the absence of further productivity gains in Total Factor Productivity, more land and water will be needed to increase food and agriculture production, straining a natural resource base already threatened by climate change.

Unable to afford higher-priced nutrient-dense foods, such as animal proteins and fruits and vegetables, consumers will rely on foods made from cheaper cereal grains for most of their calories, exacerbating skyrocketing obesity rates in adults and children.

The GAP Report describes six strategies for accelerating productivity growth: investing in public agricultural R&D and extension, embracing science- and information-based technologies, improving infrastructure and market access, cultivating partnerships for sustainable agriculture and nutrition, expanding regional and global trade, and reducing post-harvest loss and food waste.

Beginning this year, the GAP Report was produced by Virginia Tech’s College of Agriculture and Life Sciences. The GAP Report brings together expertise from Virginia Tech and other universities, the private sector, NGOs, conservation and nutrition organizations, and global research institutions. The report is part of the Global Programs Office unit within the College of Agriculture and Life Sciences that builds partnerships and creates global opportunities for students and faculty.

Productivity data for the GAP Index are provided by the USDA Economic Research Service. The GAP Report is available to view and download at www.globalagriculturalproductivity.org.

Agricultural productivity, measured as Total Factor Productivity, increases when the output of crops and livestock increases using existing, or less, land, labor, fertilizer, capital, and livestock.

The GAP Report is supported by the Virginia Tech College of Agriculture and Life Sciences and its supporting partners: Bayer Crop Science, Corteva Agriscience, John Deere, The Mosaic Company, and Smithfield Foods.

The GAP Report’s consultative partners are ACDI/VOCA, Congressional Hunger Center, Farm Foundation, Global Alliance for Improved Nutrition, HarvestPlus, Inter-American Institute for Cooperation on Agriculture, International Potato Center, The Nature Conservancy, New Markets Lab, Purdue Center for Global Food Security, Supporters of Agricultural Research Foundation, Tanager, and the Daugherty Water for Food Global Institute.


Contacts and sources:
Virginia Tech




New Calcium Batteries as Sustainable Energy Storage Systems



Calcium-based batteries promise to reach a high energy density at low manufacturing costs. This lab-scale technology has the potential for replacing lithium-ion technology in future energy storage systems. Using the electrolytes available, however, it has been impossible so far to charge calcium batteries at room temperature. In the Energy & Environmental Science journal, researchers of Karlsruhe Institute of Technology (KIT) now present a promising electrolyte class, with which this will be possible. (DOI: 10.1039/c9ee01699f)

Efficient, large, and low-cost energy storage systems will facilitate nationwide transition to zero-emission mobility and power supply. Today’s predominant lithium-ion technology, however, cannot fulfill this task on a global scale, says Professor Maximilian Fichtner of KIT, Director of the research platform CELEST (Center for Electrochemical Energy Storage Ulm & Karlsruhe). Here, calcium batteries and other storage technologies are studied. 

Zhirong Zhao-Karger (left) and Zhenyou Li (right) from the POLiS (Post Lithium Storage) Cluster of Excellence succeeded in producing promising electrolytes for calcium batteries. 
Photo: Markus Breig/KIT

“In the medium term, lithium-ion batteries will reach their limits in terms of performance and some of the resources used for their manufacture. This will prevent their future use wherever that would be reasonable for the energy transition. Availability of resources needed for manufacture, such as cobalt, nickel, and lithium, is limited.” 

At the Helmholtz Institute Ulm (HIU) established by KIT in cooperation with Ulm University, Fichtner and his team focus on alternative battery technologies instead. These technologies are based on more abundant resources. Calcium is a promising candidate, because it can release and accept two electrons per atom contrary to lithium and because it supplies a voltage similar to that of lithium: “Calcium is the fifth most abundant element in the Earth’s crust. It is distributed homogeneously on Earth and it is safe, non-toxic, and inexpensive.”

Search for a Suitable Electrolyte

Still, there has been a big obstacle in calcium battery development so far: In contrast to the established lithium-ion technology or more recent sodium or magnesium technologies, practicable electrolytes to produce rechargeable calcium batteries have been lacking so far. “For a few years now, experimental electrolytes and, hence, prototypes of the calcium battery have been available,” say Dr. Zhenyou Li, first author of the study, and Dr. Zhirong Zhao-Karger, who heads the project. 

Both are working in the POLiS (Post Lithium Storage) Cluster of Excellence of KIT that is embedded in CELEST. “But these electrolytes enable charging at temperatures beyond 75 degrees Celsius only and additionally they are susceptible to undesired side reactions.”

The researchers have now succeeded in synthesizing a class of new electrolytes based on special organic calcium salts. These electrolytes enable charging at room temperature. Using the new electrolyte calcium tetrakis[hexafluoroisopropyloxy]borate, the researchers demonstrated feasibility of calcium batteries of high energy density, storage capacity, and quick-charging capability. Their results are reported in the journal Energy & Environmental Science.

Calcium Batteries as Sustainable Energy Storage Systems

The new class of electrolytes is an important basis for transferring calcium batteries from the laboratory to application. In electric vehicles, mobile electronic devices, and stationary storage systems, they might replace the presently predominating lithium-ion battery one day. But this may take a while: “The new electrolytes are a first important step,” Fichtner emphasizes. “There still is a far way to go to the mature calcium battery.”


Contacts and sources:
Karlsruhe Institute of Technology


Citation: Towards stable and efficient electrolytes for room-temperature rechargeable calcium batteries. Zhenyou Li, Olaf Fuhr, Maximilian Fichtner, Zhiron Zhao-Karger: Energy & Environmental Science, 2019. DOI: 10.1039/c9ee01699f.
https://pubs.rsc.org/en/content/articlelanding/2019/EE/C9EE01699F#!divAbstract


Toad Disguises Itself as Deadly Viper to Avoid Attack – World First Study Reports


The first study of a toad mimicking a venomous snake reveals that it likely imitates one of Africa’s largest vipers in both appearance and behaviour, according to results published in the Journal of Natural History.

A young adult Gaboon viper (Bitis gabonica), in Fungurume, southeastern Democratic Republic of Congo, which spends most of its time amongst the leaf litter of forest floors waiting to ambush prey. 

Photograph by Colin Tilbury.

The Congolese giant toad, a triple cheeseburger-sized prize for any predator, may use its ability to mimic the highly venomous Gaboon viper to escape being eaten. The viper has the longest snake fangs in the world and produces more venom than any other snake.

“Our study is based on ten years of fieldwork and on direct observation by researchers lucky enough to see the toad’s behaviour first-hand. We’re convinced that this is an example of Batesian mimicry, where a harmless species avoids predators by pretending to be a dangerous or toxic one,” says Dr Eli Greenbaum from the University of Texas at El Paso. “To fully test our hypothesis, we’d have to demonstrate that predators are successfully duped, but this would be very difficult in the wild, where the toads are only encountered rarely. However, based on multiple sources of evidence provided in our study, we are confident that our mimicry hypothesis is well-supported.”

A side-by-side comparison between a subadult toad and subadult Gaboon viper from an aerial perspective, showing the similarities in appearance
Credit: Taylor Francis

The researchers made comparisons between the appearance of the toad, found in central African rainforests, and the viper, which is more widespread in central, eastern and southern Africa. Using live wild-caught and captive specimens, as well as preserved museum ones, they found that the colour pattern and shape of the toad’s body is similar to that of the viper’s head. Most striking are two dark brown spots and a dark brown stripe that extends down the toad’s back, the triangular shape of the body, a sharp demarcation between the tan back and dark brown flanks, and the species’ extraordinarily smooth skin for a toad. Because the Gaboon viper is capable of causing deadly bites, would-be predators likely avoid the similar-looking toads to ensure they don’t make a lethal mistake.

Some mimics are exclusively visual, but for the Congolese giant toad, getting the look right is only part of the impersonation. If a Gaboon viper feels threatened, it will often incline its head and emit a long, loud warning hiss before it actually makes a strike. Similarly, Congolese herpetologist Chifundera Kusamba observed the toad emitting a hissing noise resembling the sound of air being slowly released from a balloon. Over a century ago, American biologist James Chapin observed a bow display by the toad, where the front limbs no longer prop up the viperine-shaped body, which looks similar to the cocked head of a snake threatening to strike.

The final part of the impersonation is getting the location right. Even the best impression will only work if predators of the harmless species are familiar with the venomous one. The researchers compared the geographical range of the toad and viper in the Democratic Republic of Congo (DRC) and found that the Congolese giant toad does not seem to occur in areas where the Gaboon viper is absent. The researchers identified 11 locations in the eastern rainforests where the range of both species overlaps.

An image of the toad species (Sclerophrys channingi) that is thought to mimic the viper, based on extensive observations. 

Photograph by Konrad Mebert

Based on speciation dating estimates from genetic data, the Congolese giant toad and Gaboon viper first evolved at about the same time in the early Pliocene about 4–5 million years ago. Considered with their similar appearance, behaviour, and overlapping geographic distribution, the toads and vipers likely coevolved together, further supporting the mimicry hypothesis.

“Given the relatively large size and therefore calorific value of this toad compared to other species, it would make tempting prey to a large variety of generalist predators, including primates and other mammals, lizards, snakes and birds,” says Kusamba, from the Centre de Recherche en Sciences Naturelles, DRC. “Many of these predators use vision to find their prey, and because the viper is deadly venomous, they probably recognise the distinctive, contrasting markings from a considerable distance and avoid the toad because of them, receiving a threatening hiss if the appearance doesn’t put them off.”

Perhaps the best-known examples of Batesian mimicry are in butterflies, where around a quarter of over 200 Papilio swallowtail butterfly species are non-toxic impersonators of toxic ones. Other examples from the animal kingdom include comet fish that fool predators into thinking their tail is a moray eel’s head, the Brazilian galliwasp lizard that mimics a toxic millipede, and zebra sharks that take on the coloration and undulating movements of venomous sea snakes. Many harmless snakes mimic venomous ones, and some caterpillars, legless lizards, and even birds are able to do so. However, the current study is the first to identify an amphibian mimicking a venomous snake.
https://doi.org/10.1080/00222933.2019.1669730




Contacts and sources:
Taylor and Francis

Citation: A remarkable example of suspected Batesian mimicry of Gaboon Vipers (Reptilia: Viperidae: Bitis gabonica) by Congolese Giant Toads (Amphibia: Bufonidae: Sclerophrys channingi)  JOURNAL OF NATURAL HISTORY 2019, VOL. 53, NOS. 29–30, 1853–1871,  







Soil on Moon and Mars Likely to Support Crops



Researchers at Wageningen University & Research in the Netherlands have produced crops in Mars and Moon soil simulant developed by NASA. The research supports the idea that it would not only be possible to grow food on Mars and the Moon to feed future settlers, but also to obtain viable seed from crops grown there.


Wieger Wamelink and his colleagues at Wageningen University & Research, cultivated ten different crops: garden cress, rocket, tomato, radish, rye, quinoa, spinach, chives, peas and leek. The researchers simulated the properties of Lunar and Martian regolith and “normal” soil (potting soil from Earth) as a control.

Lunar regolith

Credit: NASA / Buzz Aldrin

Nine of the ten crops sown grew well and edible parts were harvested from them. Spinach was the exception. Total biomass production per tray was the highest for the Earth control and Mars soil simulant that differed significantly from Moon soil simulant. The seeds produced by three species (radish, rye and garden cress) were tested successfully for germination.

The article, “Crop growth and viability of seeds on Mars and Moon soil simulants”, by Wieger Wamelink and colleagues has been published in De Gruyter’s open access journal, Open Agriculture.

“We were thrilled when we saw the first tomatoes ever grown on Mars soil simulant turning red. It meant that the next step towards a sustainable closed agricultural ecosystem had been taken,” said Wieger Wamelink.

The paper can be read for free, here: https://doi.org/10.1515/opag-2019-0051


Contacts and sources:
Eric Merkel-Sobotta
De Gruyter


Citation: Crop growth and viability of seeds on Mars and Moon soil simulants. G.W.W. Wamelink, J.Y. Frissel, W.H.J. Krijnen, M.R. Verwoert. Open Agriculture, 2019; 4 (1): 509 DOI: 10.1515/opag-2019-0051

Private Property, Not Productivity, Precipitated Neolithic Agricultural Revolution


Humankind first started farming in Mesopotamia about 11,500 years ago. Subsequently, the practices of cultivating crops and raising livestock emerged independently at perhaps a dozen other places around the world, in what archaeologists call the Neolithic Agricultural Revolution. It's one of the most thoroughly-studied episodes in prehistory -- but a new paper in the Journal of Political Economy shows that most explanations for it don't agree with the evidence, and offers a new interpretation.

With farming came a vast expansion of the realm over which private property governed access to valued goods, replacing the forager social norms around sharing food upon acquisition. A common explanation is that farming increased labor productivity, which then encouraged the adoption of private property by providing incentives for the long-term investments required in a farming economy.

Babylon Dog
Credit:  Wikimedia Commons

"But it's not what the data are telling us", says Santa Fe Institute economist Samuel Bowles, a co-author of the paper. "It is very unlikely that the number of calories acquired from a day's work at the advent of farming made it a better option than hunting and gathering and it could well have been quite a bit worse."

Prior studies, including those of human and animal bones, suggest that farming actually took an extreme nutritional toll on early adopters and their livestock. So why farm in the first place?

Some have suggested an inferior technology could have been imposed by political elites as a strategy for extracting taxes, tribute, or rents. But farming was independently adopted millennia before the emergence of governments or political elites capable of imposing a new way of life on heavily-armed foraging communities.

Bowles and co-author Jung-Kyoo Choi, an economist at Kyungpook National University in South Korea, use both evolutionary game theory and archaeological evidence to propose a new interpretation of the Neolithic. Based on their model, a system of mutually recognized private property rights was both a precondition for farming and also a means of limiting costly conflicts among members of a population. While rare among foragers, private property did exist among a few groups of sedentary hunter-gatherers. Among them, farming could have benefited the first adopters because it would have been easier to establish the private possession of cultivated crops and domesticated animals than for the diffuse wild resources on which hunter-gatherers relied.

"It is a lot easier to define and defend property rights in a domesticated cow than in a wild kudu," says Choi. "Farming initially succeeded because it facilitated a broader application of private property rights, not because it lightened the toil of making a living."

Contacts and sources:
J Marshall
Santa Fe Institute

Citation:



Piranha Fish Swap Old Teeth for New Simultaneously



A CT-scanned image of the piranha Serrasalmus medinai. Note the ingested fish fins in its stomach.University of Washington

Piranha fish have a powerful bite. Their teeth help them shred through the flesh of their prey or even scrape plants off rocks to supplement their diet.

Years ago, scientists discovered that piranhas lose all of the teeth on one side of their mouth at once and regrow them, presumably to replace dulled teeth with brand new sharp spears for gnawing on prey. But no museum specimens have ever shown this theory to be true, and there’s no documentation of piranhas missing an entire block of teeth.

A live piranha, Serrasalmus.




Credit: Matthew Kolmann

With the help of new technologies, a team led by the University of Washington has confirmed that piranhas — and their plant-eating cousins, pacus — do in fact lose and regrow all the teeth on one side of their face multiple times throughout their lives. How they do it may help explain why the fish go to such efforts to replace their teeth.



The findings were published Aug. 26 in the journal Evolution & Development.

“I think in a sense we found a solution to a problem that’s obvious, but no one had articulated before,” said senior author Adam Summers, a professor of biology and of aquatic and fishery sciences at UW Friday Harbor Laboratories on San Juan Island.

“The teeth form a solid battery that is locked together, and they are all lost at once on one side of the face. The new teeth wear the old ones as ‘hats’ until they are ready to erupt. So, piranhas are never toothless even though they are constantly replacing dull teeth with brand new sharp ones.”

A CT-scanned image, left, of the red-bellied piranha (Pygocentrus nattereri) shows a set of lower teeth growing below the existing teeth. An advanced imaging technique, right, of the same fish illuminates the replacement teeth on both the bottom and top of the jaw.

Credit: University of Washington/George Washington University

The team of researchers joined their expertise in evolutionary history, biomechanical properties of fish and powerful imaging technologies to piece together the unlikely story of how piranhas and pacus lose and replace their teeth. With new teeth waiting in the wings, the fish are never missing a full set of pearly whites.

See more photos, videos

Once the researchers discovered how the teeth were being replaced, they began to understand why the fish likely employ this tactic. Using an advanced imaging technique, they were able to see clearly the contours and topography of the teeth inside various fish specimens. They found that the teeth on each side were interlocked together, forming two strong blocks within each mouth.

Scanning electron microscopy imaging shows how piranha teeth interlock.F

Credit: Frances Irish/Moravian College

“When one tooth wears down, it becomes hard to replace just one,” lead author Matthew Kolmann, a postdoctoral researcher at George Washington University who started this work with Summers as a researcher at Friday Harbor Labs. “Once you link teeth together, if one wears too much, it becomes like a missing link in an assembly line. They all have to work together in a coordinated way.”

The interlocking teeth likely benefit the fish, allowing them to distribute stress over all of their teeth when chewing. The tradeoff of having to lose an entire set of teeth all at once is perhaps worth it over the course of their lives, the researchers explained.

“With interlocking teeth, the fish go from having one sharp tooth that can crack a nut or cut through flesh to a whole battery of teeth,” said co-author Karly Cohen, a UW biology doctoral student. “Among piranhas and pacus there’s a lot of diversity in how the teeth lock together, and it seems to relate to how the teeth are being used.”

Scanning electron microscopy imaging shows a close-up of the interlocking “clasp” mechanism of the lower jaw teeth of a disk pacu (Myloplus schomburgkii)

Credit: .George Washington University

The researchers leveraged state-of-the-art analysis techniques to examine in detail the specimens of dozens of piranhas and pacus. They CT-scanned 93 specimens of 40 different species, digitizing the bones and connective tissues for high-resolution, 3D examination. They also stained the tissues of fish to see how teeth develop and incorporated hereditary information about each species to understand their evolutionary relationships with each other.

“By combining all of these things, we got a more holistic idea of what’s going on,” Cohen said.

These techniques showed a clear pattern of tooth replacement in nearly every piranha and pacu fish they examined. The imaging tools allowed them to see what wasn’t visible before to the naked eye in the specimens — rows of teeth poking to the surface underneath the existing teeth of fish.

A tissue-staining technique shows a cross section of a red-bellied piranha (Pygocentrus nattereri) jaw. The conical, left-pointing shapes are developing replacement teeth.


Credit: .George Washington University

Additionally, the project teased new information out of dozens of fish specimens that sat on the shelves of natural history museums around the country.

“The motivation for this work came out of an effort to take those collections and come up with new ways of learning about the biology of fish,” Kolmann said.

The other co-authors are Katherine Bemis of Virginia Institute of Marine Science; Frances Irish of Moravian College; and L. Patricia Hernandez of George Washington University.

This research was funded by the National Science Foundation, the National Institutes of Health, the Clyde D. & Lois W. Marlatt, Jr. Fellowship and Friday Harbor Laboratories.




Contacts and sources:
Michelle Ma
University of Washington




Pulpí Geode Will Hold a Person: Giant 11 Meter Hollow Ovoid Transparent Crystals Discovered



The geode of Pulpí is an 11-meter hollow ovoid with crystal-paneled walls. It is like those familiar couplets of stone interiors covered with bright crystallites, but so large that several people can fit inside. The crystals, of up to two meters in size, are so transparent that they look like ice crystals. In this paper for Geology, Juan Manuel García-Ruiz and colleagues reveal the geological history that ended with the formation of the Pulpí geode.

The geode of Pulpí. 
Photo by Hector Garrido.

Like the giant crystals of Naica in Mexico (see the 2007 Geology article by García-Ruiz and colleagues at https://pubs.geoscienceworld.org/gsa/geology/article/35/4/327/129804/), the crystals of Pulpí are gypsum (calcium sulfate with two water molecules). García-Ruiz says, “To reveal their formation has been a very tough task because unlike in the case of Naica, where the hydrothermal system is still active, the large geode of Pulpí is a fossilized environment.”

The team performed a study of the geology and geochemistry of the abandoned mine where the geode was found, including a detailed mapping of the underground mining works, which has been used to allow the tourist visits in the mine.

Episodic growth fronts in a meter-size crystal. 
Photo by Hector Garrido.

Video of the crystal cave: https://www.dropbox.com/s/c3dziwp1gd6kbou/PULPI%201.Ingles.mov?dl=0

They found that the crystals of Pulpi formed at around 20 °C, at a shallow depth where the temperature fluctuations of the climate are still perceptible. These temperature fluctuations, being below the maximum solubility of gypsum (40 °C), led to the dissolution and recrystallization amplifying a maturation process that is known as Ostwald maturation.

The team in the mine. 
Photo by Hector Garrido.

Says García-Ruiz, “This is somewhat like the temperature cycles in crystal quality control in industrial processes.” A continuous supply of salt for the formation of the crystals was provided by the dissolution of anhydrite (the anhydrous form of calcium sulfate), the mechanism accounting for the formation of the large crystals of Naica.

The Mina Rica in the Sierra del Aguilón, Pulpí, Almeria.
 Photo by Javier Trueba.


Because of their purity, the crystals forming the geode cannot be dated precisely. But indirect constraint can be done: “They grew for sure after the desiccation of the Mediterranean Sea that occurred 5.6 million years ago. They are most probably younger than two million years but older than 60.000 years because this is the age of the carbonate crust coating one of the large gypsum crystal,” says García-Ruiz.




Contacts and sources:
Kea Giles
Geological Society of America

Citation: The origin of large gypsum crystals in the Geode of Pulpí (Almería, Spain)
A. Canals; A.E.S. Van Driessche; F. Palero; J.M. García-Ruiz (contact: juanmanuel.garcia@csic.es)
URL: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G46734.1/574380/The-origin-of-large-gypsum-crystals-in-the-Geode

GEOLOGY articles are online at http://geology.geoscienceworld.org/content/early/recentContacts and sources:



No Evidence That Power Posing Works



Striking a power pose before an important meeting or interview is not going to boost your confidence or make you feel more powerful, says an Iowa State University researcher.

The concept of power posing – think of a Wonder Woman stance – gained popularity after a 2010 study reported that people who adopted an expansive physical pose decreased cortisol levels (an indicator of stress), increased testosterone levels and felt more powerful and willing to take risks.

Amy Cuddy demonstrating her theory of "power posing" at PopTech 2011, that assuming a posture associated with authority alters hormone levels in the body.

Credit: Erik (HASH) Hersman from Orlando / Wikimedia Commons

However, Marcus Credé, an associate professor of psychology at Iowa State, says there is not a single study to support the claims that power posing works.

Not long after the original study was published it drew criticism because the results could not be replicated. In 2018, the researchers responded to critics by presenting an updated analysis of their own research and other studies on power posing to support their claims. In a new commentary, published by the open-access journal Meta-Psychology, Credé reviewed every study on power posing as well as the analysis the researchers provided and found a significant flaw.


Marcus Credé

Credit: ISU

Nearly all of the studies he reviewed were poorly designed and failed to compare power poses to normal poses. Instead, they only compared power poses to contractive ones, such as slouching. Credé says not having a neutral pose for comparison can skew the results. That’s because any difference between a power pose and a contractive pose could occur because a contractive pose makes you feel worse, rather than an expansive pose making you feel better.

The lack of oversight is troubling, Credé said, knowing that dozens of researchers have worked on this issue and never identified the problem. What he finds even more concerning is the number of people who have bought into the concept. A TED Talk on power posing has been viewed more than 70 million times and a book on power posing was a New York Times bestseller.

“There has literally never been a study that compared a power pose to a normal pose and found any positive effect for a power pose,” Credé said. “I find this pretty stunning because of the multimillion-dollar industry that has been built up around power posing. It is not dissimilar to a drug being sold to the public without a single study ever having been able to show that the drug works better than placebo or doing nothing.”

Feelings of power diminished when compared to neutral pose

Only four of the nearly 40 studies that exist on power posing were designed in such a way as to shed light on the benefits, Credé said. One of those studies compared the effect of slouched, neutral and power poses on feelings of dominance. According to the findings, feelings of dominance were highest in the neutral position and the power pose was associated with diminished feelings of power.

Similarly, three other studies examined the three poses to determine the effect on mood. All reported significant differences in mood for different poses, but Credé says the results are driven by the negative effect of the slouching posture.

“The only conclusion researchers should draw from the existing literature on postural feedback is that contractive poses such as slouching should be avoided, which is hardly novel,” he said. “I recall my elementary school teachers yelling at us about slouching and not what has been sold here.”


Contacts and sources:
Angie Hunt
Iowa State University

Citation: A Negative Effect of a Contractive Pose is not Evidence for the Positive Effect of an Expansive Pose: Comment on Cuddy, Schultz, and Fosse (2018). Marcus Crede. Meta-Psychology, 2019; 3 DOI: 10.15626/MP.2019.1723




Saturday, October 12, 2019

MIT Programmed Viruses To Infect and Kill Bacteria

By tweaking bacteriophage genomes, a MIT team created a new weapon to combat infection.

In the battle against antibiotic resistance, many scientists have been trying to deploy naturally occurring viruses called bacteriophages that can infect and kill bacteria. 

MIT engineers have programmed viruses called bacteriophages to kill different strains of E. coli, by making mutations in a viral protein that binds to host cells.
MIT engineers have programmed viruses called bacteriophages to kill different strains of E. coli, by making mutations in a viral protein that binds to host cells.
Image courtesy of the researchers

Bacteriophages kill bacteria through different mechanisms than antibiotics, and they can target specific strains, making them an appealing option for potentially overcoming multidrug resistance. However, quickly finding and optimizing well-defined bacteriophages to use against a bacterial target is challenging.

In a new study, MIT biological engineers showed that they could rapidly program bacteriophages to kill different strains of E. coli by making mutations in a viral protein that binds to host cells. These engineered bacteriophages are also less likely to provoke resistance in bacteria, the researchers found.

“As we’re seeing in the news more and more now, bacterial resistance is continuing to evolve and is increasingly problematic for public health,” says Timothy Lu, an MIT associate professor of electrical engineering and computer science and of biological engineering. “Phages represent a very different way of killing bacteria than antibiotics, which is complementary to antibiotics, rather than trying to replace them.”

The researchers created several engineered phages that could kill E. coli grown in the lab. One of the newly created phages was also able to eliminate two E. coli strains that are resistant to naturally occurring phages from a skin infection in mice.

Lu is the senior author of the study, which appears in the Oct. 3 issue of Cell. MIT postdoc Kevin Yehl and former postdoc Sebastien Lemire are the lead authors of the paper.

Engineered viruses

The Food and Drug Administration has approved a handful of bacteriophages for killing harmful bacteria in food, but they have not been widely used to treat infections because finding naturally occurring phages that target the right kind of bacteria can be a difficult and time-consuming process.

To make such treatments easier to develop, Lu’s lab has been working on engineered viral “scaffolds” that can be easily repurposed to target different bacterial strains or different resistance mechanisms.

“We think phages are a good toolkit for killing and knocking down bacteria levels inside a complex ecosystem, but in a targeted way,” Lu says.

In 2015, the researchers used a phage from the T7 family, which naturally kills E.coli, and showed that they could program it to target other bacteria by swapping in different genes that code for tail fibers, the protein that bacteriophages use to latch onto receptors on the surfaces of host cells.

While that approach did work, the researchers wanted to find a way to speed up the process of tailoring phages to a particular type of bacteria. In their new study, they came up with a strategy that allows them to rapidly create and test a much greater number of tail fiber variants.

From previous studies of tail fiber structure, the researchers knew that the protein consists of segments called beta sheets that are connected by loops. They decided to try systematically mutating only the amino acids that form the loops, while preserving the beta sheet structure.

“We identified regions that we thought would have minimal effect on the protein structure, but would be able to change its binding interaction with the bacteria,” Yehl says.

They created phages with about 10,000,000 different tail fibers and tested them against several strains of E. coli that had evolved to be resistant to the nonengineered bacteriophage. One way that E. coli can become resistant to bacteriophages is by mutating “LPS” receptors so that they are shortened or missing, but the MIT team found that some of their engineered phages could kill even strains of E. coli with mutated or missing LPS receptors.

This helps to overcome one of the limiting factors in using phages as antimicrobials, which is that bacteria can generate resistance by mutating receptors that the phages use to enter bacteria, says Rotem Sorek, a professor of molecular genetics at the Weizmann Institute of Science.

“Through deep understanding of the biology entailing the phage-bacteria recognition, together with smart bioengineering approaches, Lu and his team managed to design a large library of phage variants, each of which has the potential to recognize a slightly different receptor. They show that treating bacteria with this library rather than with a single phage limits the emergence of resistance,” says Sorek, who was not involved in the study.

Other targets

Lu and Yehl now plan to apply this approach to targeting other resistance mechanisms used by E. coli, and they also hope to develop phages that can kill other types of harmful bacteria. “This is just the beginning, as there are many other viral scaffolds and bacteria to target,” Yehl says. The researchers are also interested in using bacteriophages as a tool to target specific strains of bacteria that live in the human gut and cause health problems.

“Being able to selectively hit those nonbeneficial strains could give us a lot of benefits in terms of human clinical outcomes,” Lu says.

The research was funded by the Defense Threat Reduction Agency, the National Institutes of Health, the U.S. Army Research Laboratory/Army Research Office through the MIT Institute for Soldier Nanotechnologies, and the Koch Institute Support (core) Grant from the National Cancer Institute.



Contacts and sources:
Anne Trafton
Massachusetts Institute of Technology (MIT)





Could Graphene-Lined Clothing Prevent Mosquito Bites?



A new study shows that graphene sheets can block the signals mosquitoes use to identify a blood meal, potentially enabling a new chemical-free approach to mosquito bite prevention.
 
The nanomaterial graphene has received significant attention for its potential uses in everything from solar cells to tennis rackets. But a new study by Brown University researchers finds a surprising new use for the material: preventing mosquito bites.

In a paper published in Proceedings of the National Academy of Sciences, researchers showed that multilayer graphene can provide a two-fold defense against mosquito bites. The ultra-thin yet strong material acts as a barrier that mosquitoes are unable to bite through. At the same time, experiments showed that graphene also blocks chemical signals mosquitoes use to sense that a blood meal is near, blunting their urge to bite in the first place. The findings suggest that clothing with a graphene lining could be an effective mosquito barrier, the researchers say.

“Mosquitoes are important vectors for disease all over the world, and there’s a lot of interest in non-chemical mosquito bite protection,” said Robert Hurt,a professor in Brown’s School of Engineering, leader of Brown's Superfund Research Program and senior author of the paper. “We had been working on fabrics that incorporate graphene as a barrier against toxic chemicals, and we started thinking about what else the approach might be good for. We thought maybe graphene could provide mosquito bite protection as well.”

Researchers created an experimental setup to see if graphene could prevent mosquito bites.

Credit: Brown University

To find out if it would work, the researchers recruited some brave participants willing to get a few mosquito bites in the name of science. The participants placed their arms in a mosquito-filled enclosure so that only a small patch of their skin was available to the mosquitoes for biting. The mosquitoes were bred in the lab so they could be confirmed to be disease-free.

The researchers compared the number of bites participants received on their bare skin, on skin covered in cheesecloth and on skin covered by a graphene oxide (GO) films sheathed in cheesecloth. GO is a graphene derivative that can be made into films large enough for macro-scale applications.

It was readily apparent that graphene was a bite deterrent, the researchers found. When skin was covered by dry GO films, participants didn’t get a single bite, while bare and cheesecloth-covered skin was readily feasted upon. What was surprising, the researchers said, was that the mosquitoes completely changed their behavior in the presence of the graphene-covered arm.

“With the graphene, the mosquitoes weren’t even landing on the skin patch — they just didn’t seem to care,” said Cintia Castillho, a Ph.D. student at Brown and the study’s lead author. “We had assumed that graphene would be a physical barrier to biting, through puncture resistance, but when we saw these experiments we started to think that it was also a chemical barrier that prevents mosquitoes from sensing that someone is there.”

To confirm the chemical barrier idea, the researchers dabbed some human sweat onto the outside of a graphene barrier. With the chemical ques on the other side of the graphene, the mosquitoes flocked to the patch in much the same way they flocked to bare skin.

Other experiments showed that GO can also provide puncture resistance — but not all the time. Using a tiny needle as a stand-in for a mosquito’s proboscis, as well as computer simulations of the bite process, the researchers showed that mosquitoes simply can’t generate enough force to puncture GO. But that only applied when the GO is dry. The simulations found that GO would be vulnerable to puncture when it was saturated with water. And sure enough, experiments showed that mosquitoes could bite through wet GO. However, another form of GO with reduced oxygen content (called rGO) was shown to provide a bite barrier when both wet and dry.


A graphene oxide film was shown to prevent mosquito bites when dry.
Credit: Brown University


A next step for the research would be to find a way to stabilize the GO so that it’s tougher when wet, Hurt says. That’s because GO has a distinct advantage over rGO when it comes to wearable technology.

“GO is breathable, meaning you can sweat through it, while rGO isn’t,” Hurt said. “So our preferred embodiment of this technology would be to find a way to stabilize GO mechanically so that is remains strong when wet. This next step would give us the full benefits of breathability and bite protection.”

All told, the researchers say, the study suggests that properly engineered graphene linings could be used to make mosquito protective clothing.

Other co-authors on the study were Dong Li, Muchun Liu, Yue Liu and Huajian Gao. The study was funded by the National Institute of Environmental Health Sciences, Superfund Research Program, and the National Science Foundation (CMMI-1634492).


Contacts and sources:
Kevin Stacey
Brown University






Ice on Lunar South Pole May Have More than One Source, Suggests Study



New research sheds light on the ages of ice deposits reported in the area of the Moon’s south pole — information that could help identify the sources of the deposits and help in planning future human exploration.

Shackleton Crater, the floor of which is permanently shadowed from the sun, appears to be home to deposits of water ice. A new study sheds light on how old these and other deposits on the Moon's south pole might be.

A new study sheds light on how old these and other deposits on the Moon's south pole might be. Shackleton crater is nearly coincident with the Moon’s south pole. Its interior receives almost no direct sunlight and is a perennial cold trap, making Shackleton a promising candidate location in which to seek sequestered volatiles

Credit: NASA

The discovery of ice deposits in craters scattered across the Moon’s south pole has helped to renew interest in exploring the lunar surface, but no one is sure exactly when or how that ice got there. A new study published in the journal Icarus suggests that while a majority of those deposits are likely billions of years old, some may be much more recent.

Ariel Deutsch, a graduate student in Brown University’s Department of Earth, Environmental and Planetary Sciences and the study’s lead author, says that constraining the ages of the deposits is important both for basic science and for future lunar explorers who might make use of that ice for fuel and other purposes.

“The ages of these deposits can potentially tell us something about the origin of the ice, which helps us understand the sources and distribution of water in the inner solar system,” Deutsch said. “For exploration purposes, we need to understand the lateral and vertical distributions of these deposits to figure out how best to access them. These distributions evolve with time, so having an idea of the age is important.”

For the study, Deutsch worked with Jim Head, a professor at Brown, and Gregory Neumann from the NASA Goddard Space Flight Center. Using data from NASA’s Lunar Reconnaissance Orbiter, which has been orbiting the Moon since 2009, the researchers looked at the ages of the large craters in which evidence for south pole ice deposits was found. To date the craters, researchers count the number of smaller craters that have accrued inside the larger ones. Scientists have an approximate idea of the pace of impacts over time, so counting craters can help establish the ages of terrains.

The majority of the reported ice deposits are found within large craters formed about 3.1 billion years or longer ago, the study found. Since the ice can’t be any older than the crater, that puts an upper bound on the age of the ice. Just because the crater is old doesn’t mean that the ice within it is also that old too, the researchers say, but in this case there’s reason to believe the ice is indeed old. The deposits have a patchy distribution across crater floors, which suggests that the ice has been battered by micrometeorite impacts and other debris over a long period of time.

If those reported ice deposits are indeed ancient, that could have significant implications in terms of exploration and potential resource utilization, the researchers say.


Credit: NASA

“There have been models of bombardment through time showing that ice starts to concentrate with depth,” Deutsch said. “So if you have a surface layer that’s old, you’d expect more underneath.”

While the majority of ice was in the ancient craters, the researchers also found evidence for ice in smaller craters that, judging by their sharp, well-defined features, appear to be quite fresh. That suggests that some of the deposits on the south pole got there relatively recently.

“That was a surprise,” Deutsch said. “There hadn’t really been any observations of ice in younger cold traps before.”

If there are indeed deposits of different ages, the researchers say, that suggests they may also have different sources. Older ice could have been sourced from water-bearing comets and asteroids impacting the surface, or through volcanic activity that drew water from deep within the Moon. But there aren’t many big water-bearing impactors around in recent times, and volcanism is thought to have ceased on the Moon over a billion years ago. So more recent ice deposits would require different sources — perhaps bombardment from pea-sized micrometeorites or implantation by solar wind.

The best way to find out for sure, the researchers say, is to send spacecraft there to get some samples. And that appears to be on the horizon. NASA’s Artemis program aims to put humans on the Moon by 2024, and plans to fly numerous precursor missions with robotic spacecraft in the meantime. Head, a study co-author and Deutsch’s Ph.D. advisor, says studies like this one will help to shape those future missions.

“When we think about sending humans back to the Moon for long-term exploration, we need to know what resources are there that we can count on, and we currently don’t know,” Head said. “Studies like this one help us make predictions about where we need to go to answer those questions.”


Contacts and sources:
Kevin Stacey
Brown University

Citation: Analyzing the ages of south polar craters on the Moon: Implications for the sources and evolution of surface water ice.. Ariel N. Deutsch, James W. Head, Gregory A. Neumann. Icarus, 2019; 113455 DOI: 10.1016/j.icarus.2019.113455




Black Holes Stunt Growth of Dwarf Galaxies


Astronomers at the University of California, Riverside, have discovered that powerful winds driven by supermassive black holes in the centers of dwarf galaxies have a significant impact on the evolution of these galaxies by suppressing star formation.

Dwarf galaxies hosting active galactic nuclei that have spatially extended outflows.
Credit: SDSS

Dwarf galaxies are small galaxies that contain between 100 million to a few billion stars. In contrast, the Milky Way has 200-400 billion stars. Dwarf galaxies are the most abundant galaxy type in the universe and often orbit larger galaxies.

The team of three astronomers was surprised by the strength of the detected winds.

“We expected we would need observations with much higher resolution and sensitivity, and we had planned on obtaining these as a follow-up to our initial observations,” said Gabriela Canalizo, a professor of physics and astronomy at UC Riverside, who led the research team. “But we could see the signs strongly and clearly in the initial observations. The winds were stronger than we had anticipated.”

Canalizo explained that astronomers have suspected for the past couple of decades that supermassive black holes at the centers of large galaxies can have a profound influence on the way large galaxies grow and age.

“Our findings now indicate that their effect can be just as dramatic, if not more dramatic, in dwarf galaxies in the universe,” she said.

Study results appear in The Astrophysical Journal.

The researchers, who also include Laura V. Sales, an assistant professor of physics and astronomy; and Christina M. Manzano-King, a doctoral student in Canalizo’s lab, used a portion of the data from the Sloan Digital Sky Survey, which maps more than 35% of the sky, to identify 50 dwarf galaxies, 29 of which showed signs of being associated with black holes in their centers. Six of these 29 galaxies showed evidence of winds — specifically, high-velocity ionized gas outflows — emanating from their active black holes.

“Using the Keck telescopes in Hawaii, we were able to not only detect, but also measure specific properties of these winds, such as their kinematics, distribution, and power source — the first time this has been done,” Canalizo said. “We found some evidence that these winds may be changing the rate at which the galaxies are able to form stars.”

From left to right: Laura Sales, Christina Manzano-King, and Gabriela Canalizo.
Credit: UCR/Stan Lim

Manzano-King, the first author of the research paper, explained that many unanswered questions about galaxy evolution can be understood by studying dwarf galaxies.

“Larger galaxies often form when dwarf galaxies merge together,” she said. “Dwarf galaxies are, therefore, useful in understanding how galaxies evolve. Dwarf galaxies are small because after they formed, they somehow avoided merging with other galaxies. Thus, they serve as fossils by revealing what the environment of the early universe was like. Dwarf galaxies are the smallest galaxies in which we are directly seeing winds — gas flows up to 1,000 kilometers per second — for the first time.”

Manzano-King explained that as material falls into a black hole, it heats up due to friction and strong gravitational fields and releases radiative energy. This energy pushes ambient gas outward from the center of the galaxy into intergalactic space.

“What’s interesting is that these winds are being pushed out by active black holes in the six dwarf galaxies rather than by stellar processes such as supernovae,” she said. “Typically, winds driven by stellar processes are common in dwarf galaxies and constitute the dominant process for regulating the amount of gas available in dwarf galaxies for forming stars.”

UC Riverside astronomers find large-scale winds associated with active black holes in small galaxies suppress star formation
Credit: UCR


Astronomers suspect that when wind emanating from a black hole is pushed out, it compresses the gas ahead of the wind, which can increase star formation. But if all the wind gets expelled from the galaxy’s center, gas becomes unavailable and star formation could decrease. The latter appears to be what is occurring in the six dwarf galaxies the researchers identified.

“In these six cases, the wind has a negative impact on star formation,” Sales said. “Theoretical models for the formation and evolution of galaxies have not included the impact of black holes in dwarf galaxies. We are seeing evidence, however, of a suppression of star formation in these galaxies. Our findings show that galaxy formation models must include black holes as important, if not dominant, regulators of star formation in dwarf galaxies.”

Next, the researchers plan to study the mass and momentum of gas outflows in dwarf galaxies.

“This would better inform theorists who rely on such data to build models,” Manzano-King said. “These models, in turn, teach observational astronomers just how the winds affect dwarf galaxies. We also plan to do a systematic search in a larger sample of the Sloan Digital Sky Survey to identify dwarf galaxies with outflows originating in active black holes.”

The research was funded by the National Science Foundation, NASA, and the Hellman Foundation. Data was obtained at the W. M. Keck Observatory, and made possible by financial support from the W. M. Keck Foundation.



Contacts and sources:
Iqbal Pittalwala
University of California - Riverside

The Milky Way Kidnapped Several Tiny Galaxies from Its Neighbor


Just like the moon orbits the Earth, and the Earth orbits the sun, galaxies orbit each other according to the predictions of cosmology. 

For example, more than 50 discovered satellite galaxies orbit our own galaxy, the Milky Way. The largest of these is the Large Magellanic Cloud, or LMC, a large dwarf galaxy that resembles a faint cloud in the Southern Hemisphere night sky.

UC Riverside-led research shows our galaxy is undergoing a massive merger with its largest satellite galaxy, the Large Magellanic Cloud

Visualization of the simulations used in the study. Top left shows dark matter in white. Bottom right shows a simulated Large Magellanic Cloud-like galaxy with stars and gas, and several smaller companion galaxies

UC Riverside-led research shows our galaxy is undergoing a massive merger with its largest satellite galaxy, the Large Magellanic Cloud
. Credit: UCR/Ethan Jahn
 

A team of astronomers led by scientists at the University of California, Riverside, has discovered that several of the small — or “dwarf” — galaxies orbiting the Milky Way were likely stolen from the LMC, including several ultrafaint dwarfs, but also relatively bright and well-known satellite galaxies, such as Carina and Fornax.

The researchers made the discovery by using new data gathered by the Gaia space telescope on the motions of several nearby galaxies and contrasting this with state-of-the-art cosmological hydrodynamical simulations. The UC Riverside team used the positions in the sky and the predicted velocities of material, such as dark matter, accompanying the LMC, finding that at least four ultrafaint dwarfs and two classical dwarfs, Carina and Fornax, used to be satellites of the LMC. Through the ongoing merger process, however, the more massive Milky Way used its powerful gravitational field to tear apart the LMC and steal these satellites, the researchers report.

Laura Sales (right), an assistant professor of physics and astronomy at UC Riverside, is seen here with Ethan Jahn, her graduate student.
Credit: UCR/Sales group

“These results are an important confirmation of our cosmological models, which predict that small dwarf galaxies in the universe should also be surrounded by a population of smaller fainter galaxy companions,” said Laura Sales, an assistant professor of physics and astronomy, who led the research team. “This is the first time that we are able to map the hierarchy of structure formation to such faint and ultrafaint dwarfs.”

The findings have important implications for the total mass of the LMC and also on the formation of the Milky Way.

“If so many dwarfs came along with the LMC only recently, that means the properties of the Milky Way satellite population just 1 billion years ago were radically different, impacting our understanding of how the faintest galaxies form and evolve,” Sales said.

Study results appear in the November 2019 issue of the Monthly Notices of the Royal Astronomical Society.

Dwarf galaxies are small galaxies that contain anywhere from a few thousand to a few billion stars. The researchers used computer simulations from the Feedback In Realistic Environments project to show the LMC and galaxies similar to it host numerous tiny dwarf galaxies, many of which contain no stars at all — only dark matter, a type of matter scientists think constitutes the bulk of the universe’s mass.


“The high number of tiny dwarf galaxies seems to suggest the dark matter content of the LMC is quite large, meaning the Milky Way is undergoing the most massive merger in its history, with the LMC, its partner, bringing in as much as one third of the mass in the Milky Way’s dark matter halo — the halo of invisible material that surrounds our galaxy,” said Ethan Jahn, the first author of the paper and a graduate student in Sales’ research group.

Jahn explained that the number of tiny dwarf galaxies the LMC hosts may be higher than astronomers previously estimated, and that many of these tiny satellites have no stars.

“Small galaxies are hard to measure, and it’s possible that some already-known ultrafaint dwarf galaxies are in fact associated with the LMC,” he said. “It’s also possible that we will discover new ultrafaints that are associated with the LMC.”

Dwarf galaxies can either be satellites of larger galaxies, or they can be “isolated,” existing on their own and independent of any larger object. The LMC used to be isolated, Jahn explained, but it was captured by the gravity of the Milky Way and is now its satellite.

“The LMC hosted at least seven satellite galaxies of its own, including the Small Magellanic Cloud in the Southern Sky, prior to them being captured by the Milky Way,” he said.

Next, the team will study how the satellites of LMC-sized galaxies form their stars and how that relates to how much dark matter mass they have.

“It will be interesting to see if they form differently than satellites of Milky Way-like galaxies,” Jahn said.

Sales and Jahn were joined in the study Andrew Wetzel of UC Davis; Michael Boylan-Kolchin of the University of Texas at Austin; T. K. Chan of UC San Diego; Kareem El-Badry of UC Berkeley; and Alexandres Lazar and James S. Bullock of UC Irvine.

The research was supported by grants to Sales from NASA and the Hellman Foundation.

Contacts and sources:
Iqbal Pittalwala
University of California - Riverside


Citation: Dark and luminous satellites of LMC-mass galaxies in the FIRE simulations.
Ethan D Jahn, Laura V Sales, Andrew Wetzel, Michael Boylan-Kolchin, T K Chan, Kareem El-Badry, Alexandres Lazar, James S Bullock. Monthly Notices of the Royal Astronomical Society, 2019; 489 (4): 5348 DOI: 10.1093/mnras/stz245



Scientists Uncover Cool, New Technological Twist for Refrigeration


This natural rubber fiber has been coated with a paint that changes color when the fiber changes temperature. University of Texas at Dallas researchers and their colleagues recently showed that when the rubber fiber is twisted, it heats up. After reaching room temperature, the fiber cools as it is subsequently untwisted. If you don’t see the video, watch it on Vimeo.

Credit: University of Texas at Dallas

An international team led by researchers at The University of Texas at Dallas and Nankai University in China has discovered a new technology for refrigeration that is based on twisting and untwisting fibers.

In research published in the Oct. 11 issue of the journal Science, they demonstrated twist-based refrigeration using materials as diverse as natural rubber, ordinary fishing line and nickel titanium wire.

“Our group has demonstrated what we call ‘twistocaloric cooling’ by changing the twist in fibers. We call coolers that use twist changes for refrigeration ‘twist fridges,’” said Dr. Ray Baughman, director of the Alan G. MacDiarmid NanoTech Institute at UT Dallas. Baughman is a corresponding author of the study, along with Dr. Zunfeng Liu, a professor in the State Key Laboratory of Medicinal Chemical Biology in the College of Pharmacy at Nankai University in Tianjin.

The Quest for New Technologies

According to the International Institute of Refrigeration, refrigeration and air conditioning consume about 20% of global electrical energy. Conventional refrigerators also release gases that significantly contribute to global warming.

As consumption continues to grow, especially due to the increasing needs of developing nations, researchers are investigating alternative cooling technologies to increase refrigeration efficiency, lower costs and reduce size.

Stretching a rubber band heats the rubber, and releasing the stretch cools it; this is called elastocaloric cooling. Other solid substances for cooling include electrocaloric and magnetocaloric materials, which cool via changes in electric and magnetic fields, respectively.

“This elastocaloric behavior of natural rubber has been known since the early 1800s. But to get high cooling from a rubber band, you have to release a very large stretch,” Baughman said. “With twistocaloric cooling, we found that all you have to do is release twist.”

The Experiments

Baughman’s research teams previously developed artificial muscles made by tightly twisting and coiling fibers that range from carbon nanotube yarns to ordinary nylon thread and polyethylene fishing line

Dr. Ray Baughman


Credit: University of Texas at Dallas

In the current work, the scientists stretched rubber fibers, then twisted them until they not only coiled, but also supercoiled. Fast release of the twist resulted in surface temperature cooling of 15.5 degrees Celsius. Releasing both the twist and the stretch from the rubber produced even higher cooling of 16.4 degrees Celsius.

The twistocaloric cooling also worked for fishing line. The researchers inserted twist into a nonelastic polymer fishing line until coils formed. Stretching the coiled fiber caused heating, while stretch release produced a maximum surface cooling of 5.1 degrees Celsius.

“By employing opposite directions of twist and coiling, we engineered fibers that cool when stretched,” said Baughman, the Robert A. Welch Distinguished Chair in Chemistry in the School of Natural Sciences and Mathematics. “This is quite unusual behavior since ordinary materials heat up when stretched.”

To investigate the origin of the cooling effect in the fishing line, the researchers turned to X-ray crystallography, which allowed them to determine what was happening on the molecular level when twist was changed by stretching a coiled fiber.

“We found that releasing stretch from a coiled fiber results in partial conversion of a low entropy phase into a high entropy phase,” Liu said. “This phase change causes twistocaloric cooling.”

Cooling

Large reversible cooling was also achieved by removing twist from nickel titanium wires and by unplying bundles of these wires. A maximum surface cooling of 17 degrees Celsius was observed when the researchers untwisted a single wire. Unplying a four-wire bundle produced even higher cooling of 20.8 degrees Celsius.

The researchers placed a three-ply nickel titanium wire cable in a device they built that cooled a stream of water by up to 7.7 degrees Celsius when the cable was unplied. “By using further cycles of twist and twist release, much higher cooling can be achieved,” Liu said.


“This elastocaloric behavior of natural rubber has been known since the early 1800s. But to get high cooling from a rubber band, you have to release a very large stretch. With twistocaloric cooling, we found that all you have to do is release twist.” says  Dr. Ray Baughman, director of the Alan G. MacDiarmid NanoTech Institute at UT Dallas

In another set of experiments, they coated the different types of fibers with thermochromic paint, which changes color in response to temperature variations produced by twisting fibers or stretching coiled fibers. Such fibers could be used for remotely readable sensors of strain and twist, as well as for color-changing textiles for clothing.

“Many challenges and opportunities exist on the path from these initial discoveries to the commercialization of twist fridges for diverse large- and small-scale applications,” Baughman said. “Among the challenges are the need to demonstrate refined devices and materials that provide application-targeted cycle lifetimes and efficiencies by recovering part of the inputted mechanical energy. The opportunities include using performance-optimized twistocaloric materials, rather than the few presently studied commercially available candidates.”

The lead authors of the study were Run Wang, a PhD candidate from Nankai University, and Dr. Shaoli Fang, associate research professor at UT Dallas’ NanoTech Institute. Other UT Dallas researchers from the NanoTech Institute include Dr. Ali Aliev, research professor, and Dr. Jiuke Mu, postdoctoral research scientist. UT Dallas’ Dr. Dong Qian and Dr. Hongbing Lu, professors of mechanical engineering, and Zhong Wang, a doctoral student in chemistry, also participated. Additional study authors included researchers from Nankai University, Georgia Southern University, Lintec of America, MilliporeSigma, the University of Campinas in Brazil, and in China: Wuhan University, Tsinghua Shenzhen International Graduate School, Tsinghua University, Tianjin University of Technology, University of Science and Technology Liaoning, and China Pharmaceutical University.

The research at UT Dallas was supported by the Air Force Office of Scientific Research, The Welch Foundation, the National Science Foundation and the Louis Beecherl Jr. Endowed Chair.


Contacts and sources:
Amanda Siegfried,University of Texas at Dallas

Citation: Torsional refrigeration by twisted, coiled, and supercoiled fibers. Run Wang, Shaoli Fang, Yicheng Xiao, Enlai Gao, Nan Jiang, Yaowang Li, Linlin Mou, Yanan Shen, Wubin Zhao, Sitong Li, Alexandre F. Fonseca, Douglas S. Galvão, Mengmeng Chen, Wenqian He, Kaiqing Yu, Hongbing Lu, Xuemin Wang, Dong Qian, Ali E. Aliev, Na Li, Carter S. Haines, Zhongsheng Liu, Jiuke Mu, Zhong Wang, Shougen Yin, Márcio D. Lima, Baigang An, Xiang Zhou, Zunfeng Liu, Ray H. Baughman. Science, 2019 DOI: 10.1126/science.aax6182




Wearable, Washable Textile Devices Are Possible With MXene-Coated Yarns



Producing functional fabrics that perform all the functions we want, while retaining the characteristics of fabric we’re accustomed to is no easy task.

Two groups of researchers at Drexel University — one, who is leading the development of industrial functional fabric production techniques, and the other, a pioneer in the study and application of one of the strongest, most electrically conductive super materials in use today — believe they have a solution.

Drexel researchers have developed a way to coat cellulose yarn with flakes of a type of conductive, two-dimensional material, called MXene, to imbue it with the conductivity and durability it needs to be knit into functional fabrics.

Credit: Drexel University


They’ve improved a basic element of textiles: yarn. By adding technical capabilities to the fibers that give textiles their character, fit and feel, the team has shown that it can knit new functionality into fabrics without limiting their wearability.

In a paper recently published in the journal Advanced Functional Materials, the researchers, led by Yury Gogotsi, PhD, Distinguished University and Bach professor in Drexel’s College of Engineering, and Genevieve Dion, a professor in Westphal College of Media Arts & Design and director of Drexel’s Center for Functional Fabrics, showed that they can create a highly conductive, durable yarn by coating standard cellulose-based yarns with a type of conductive two-dimensional material called MXene.


Credit: Drexel University

HITTING SNAGS

“Current wearables utilize conventional batteries, which are bulky and uncomfortable, and can impose design limitations to the final product,” they write. “Therefore, the development of flexible, electrochemically and electromechanically active yarns, which can be engineered and knitted into full fabrics provide new and practical insights for the scalable production of textile-based devices.”

The team reported that its conductive yarn packs more conductive material into the fibers and can be knitted by a standard industrial knitting machine to produce a textile with top-notch electrical performance capabilities. This combination of ability and durability stands apart from the rest of the functional fabric field today.

With the development of durable, conductive yarns researchers are one step closer to producing wearable devices that are both functional and fashionable.



Credit: Drexel University

Most attempts to turn textiles into wearable technology use stiff metallic fibers that alter the texture and physical behavior of the fabric. Other attempts to make conductive textiles using silver nanoparticles and graphene and other carbon materials raise environmental concerns and come up short on performance requirements. And the coating methods that are successfully able to apply enough material to a textile substrate to make it highly conductive also tend to make the yarns and fabrics too brittle to withstand normal wear and tear.

“Some of the biggest challenges in our field are developing innovative functional yarns at scale that are robust enough to be integrated into the textile manufacturing process and withstand washing,” Dion said. “We believe that demonstrating the manufacturability of any new conductive yarn during experimental stages is crucial. High electrical conductivity and electrochemical performance are important, but so are conductive yarns that can be produced by a simple and scalable process with suitable mechanical properties for textile integration. All must be taken into consideration for the successful development of the next-generation devices that can be worn like everyday garments.”
THE WINNING COMBINATION

Dion has been a pioneer in the field of wearable technology, by drawing on her background on fashion and industrial design to produce new processes for creating fabrics with new technological capabilities. Her work has been recognized by the Department of Defense, which included Drexel, and Dion, in its Advanced Functional Fabrics of America effort to make the country a leader in the field.

She teamed with Gogotsi, who is a leading researcher in the area of two-dimensional conductive materials, to approach the challenge of making a conductive yarn that would hold up to knitting, wearing and washing.

Gogotsi’s group was part of the Drexel team that discovered highly conductive two-dimensional materials, called MXenes, in 2011 and have been exploring their exceptional properties and applications for them ever since. His group has shown that it can synthesize MXenes that mix with water to create inks and spray coatings without any additives or surfactants — a revelation that made them a natural candidate for making conductive yarn that could be used in functional fabrics.

Coating cellulose yarn with conductive MXene flakes creates a highly conductive and durable material.

Credit: Drexel University



“Researchers have explored adding graphene and carbon nanotube coatings to yarn, our group has also looked at a number of carbon coatings in the past,” Gogotsi said. “But achieving the level of conductivity that we demonstrate with MXenes has not been possible until now. It is approaching the conductivity of silver nanowire-coated yarns, but the use of silver in the textile industry is severely limited due to its dissolution and harmful effect on the environment. Moreover, MXenes could be used to add electrical energy storage capability, sensing, electromagnetic interference shielding and many other useful properties to textiles.”

In its basic form, titanium carbide MXene looks like a black powder. But it is actually composed of flakes that are just a few atoms thick, which can be produced at various sizes. Larger flakes mean more surface area and greater conductivity, so the team found that it was possible to boost the performance of the yarn by infiltrating the individual fibers with smaller flakes and then coating the yarn itself with a layer of larger-flake MXene.
PUTTING IT TO THE TEST

The team created the conductive yarns from three common, cellulose-based yarns: cotton, bamboo and linen. They applied the MXene material via dip-coating, which is a standard dyeing method, before testing them by knitting full fabrics on an industrial knitting machine — the kind used to make most of the sweaters and scarves you’ll see this fall.

Each type of yarn was knit into three different fabric swatches using three different stitch patterns — single jersey, half gauge and interlock — to ensure that they are durable enough to hold up in any textile from a tightly knit sweater to a loose-knit scarf.

MXene-coated yarns were tested by using them to knit textiles in three common patterns — single jersey, half gauge and interlock — to determine the optimal configuration for knitting with the conductive yarn.

Credit: Drexel University



“The ability to knit MXene-coated cellulose-based yarns with different stitch patterns allowed us to control the fabric properties, such as porosity and thickness for various applications,” the researchers write.

To put the new threads to the test in a technological application, the team knitted some touch-sensitive textiles — the sort that are being explored by Levi’s and Yves Saint Laurent as part of Google’s Project Jacquard.

Not only did the MXene-based conductive yarns hold up against the wear and tear of the industrial knitting machines, but the fabrics produced survived a battery of tests to prove its durability. Tugging, twisting, bending and — most importantly — washing, did not diminish the touch-sensing abilities of the yarn, the team reported — even after dozens of trips through the spin cycle.

PUSHING FORWARD

But the researchers suggest that the ultimate advantage of using MXene-coated conductive yarns to produce these special textiles is that all of the functionality can be seamlessly integrated into the textiles. So instead of having to add an external battery to power the wearable device, or wirelessly connect it to your smartphone, these energy storage devices and antennas would be made of fabric as well — an integration that, though literally seamed, is a much smoother way to incorporate the technology.

“Electrically conducting yarns are quintessential for wearable applications because they can be engineered to perform specific functions in a wide array of technologies,” they write.

Using conductive yarns also means that a wider variety of technological customization and innovations are possible via the knitting process. For example, “the performance of the knitted pressure sensor can be further improved in the future by changing the yarn type, stitch pattern, active material loading and the dielectric layer to result in higher capacitance changes,” according to the authors.

Drexel's Center for Functional Fabrics is leading research in the development of new yarn and textile technology.

Credit: Drexel University


Dion’s team at the Center for Functional Fabrics is already putting this development to the test in a number of projects, including a collaboration with textile manufacturer Apex Mills — one of the leading producers of material for car seats and interiors. And Gogotsi suggests the next step for this work will be tuning the coating process to add just the right amount of conductive MXene material to the yarn for specific uses.

“With this MXene yarn, so many applications are possible,” Gogotsi said. “You can think about making car seats with it so the car knows the size and weight of the passenger to optimize safety settings; textile pressure sensors could be in sports apparel to monitor performance, or woven into carpets to help connected houses discern how many people are home — your imagination is the limit.”

In addition to Gogotsi and Dion, Drexel College of Engineering doctoral students Simge Uzun, Mohamed Alhabeb, Ariana S. Levitt, Mark Anayee; Amy L. Stoltzfus, a master’s student in Westphal College; Christina J. Strobel, an undergraduate in the College of Engineering; and Joselito M. Razal, and Shayan Seyedin, researchers at Deakin University in Australia, contributed to this research. The work was supported by the U.S. Department of Energy.

Read the full paper here: https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201905015




Contacts and sources:
Drexel University


Citation: Knittable and Washable Multifunctional MXene‐Coated Cellulose Yarns. Simge Uzun, Shayan Seyedin, Amy L. Stoltzfus, Ariana S. Levitt, Mohamed Alhabeb, Mark Anayee, Christina J. Strobel, Joselito M. Razal, Genevieve Dion, Yury Gogotsi. Advanced Functional Materials, 2019; 1905015 DOI: 10.1002/adfm.201905015