Date:
August 11, 2016

Source:
New Jersey Institute of Technology

Summary:
Batches of sand from a beach on the Delaware Bay are yielding insights into the powerful impact of temperature rise and evaporation along the shore that are in turn challenging long-held assumptions about what causes beach salinity to fluctuate in coastal zones that support a rich network of sea creatures and plants.

 

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Researchers have developed models that show that increases in temperature associated with global warming will not only make inland locations more salty, but would also create drastically different pattern of pore water salinity that will have implications for animals and plants in the intertidal zone.
Credit: © Vladimir Sazonov / Fotolia

 

 

Batches of sand from a beach on the Delaware Bay are yielding insights into the powerful impact of temperature rise and evaporation along the shore that are in turn challenging long-held assumptions about what causes beach salinity to fluctuate in coastal zones that support a rich network of sea creatures and plants.

The findings have implications for the migration and survival of invertebrates such as mussels and crabs as global warming drives temperatures higher.

A first major study of the effects of evaporation on the flow of subsurface water and salinity, or salt content, in the beach intertidal zone — the section of the beach between the low and high tide marks — is being published today in Scientific Reports, an online affiliate of Nature.

The study, by New Jersey Institute of Technology’s Center for Natural Resources Development (CNRDP) and led by two environmental engineers and a coastal geologist, shows that sediments from some sections of Slaughter Beach in Delaware have salt concentrations four times as high as the ocean water that washes over them. The finding came as a surprise.

The nearshore seawater the team measured had salt concentrations of 25 grams per liter (g/L), leading the researchers to expect that the subsurface water in areas of the beach it infiltrated would have similar or even lower levels as seawater mixes with inland groundwater in this zone. However, they discovered that the average salinity in the upper intertidal zone — the high tide line — was 60 g/L, with some values reaching as high as 100.

“These elevated levels can only be caused by evaporation, as there is no other mechanism for increasing the salt in pore water — the water trapped between the grains of sediment,” said Xiaolong Geng, a postdoctoral fellow at NJIT and the principal author of the study, noting that the rates of evaporation — and salinity — are thus mainly determined by temperature and relative humidity, while tide and wave flows dilute a beach’s salt content.

“Previous studies have identified seawater as the primary source of salinity in coastal aquifer systems, thereby concluding that seawater infiltration always increases pore-water salinity by seawater-groundwater mixing dynamics,” said Michel Boufadel, director of the CNRDP, who is also an author of the study. “Based on what we learned, we think this finding should alter the way water management in coastal areas is conducted.”

The team analyzed nearly 400 sediment samples collected during the sequential phases of a complete tidal cycle, from day to night, on seven discontinuous days.

The intertidal, or littoral, zone, is a dynamic habitat, washed by seawater at high tide and uncovered at low tide, that is favored by crabs, mussels and sea anemones, the birds and sea mammals that feed on them, and plants such as kelp. Many of these animals burrow in the beach to find food and to seek protection from predators and the action of waves, and are in near constant contact with pore water.

The researchers have developed models that show that increases in temperature associated with global warming will not only make inland locations more salty, but would also create drastically different pattern of pore water salinity that will have implications for animals and plants in the intertidal zone.

“Evaporation is an important driver of underground water flow and salinity gradients, and animals such as mussels and crabs are affected by changes in salinity. If the concentrations are too high or too low, they will move away,” noted Geng.

Nancy Jackson, a professor of coastal geomorphology in the Department of Chemistry and Environmental Science and the study’s third author, collected the beach samples from Slaughter Beach and provided interpretations of pore water dynamics.


Story Source:

The above post is reprinted from materials provided by New Jersey Institute of Technology. Note: Content may be edited for style and length.


Journal Reference:

  1. Xiaolong Geng, Michel C. Boufadel, Nancy L. Jackson. Evidence of salt accumulation in beach intertidal zone due to evaporation.Scientific Reports, 2016; 6: 31486 DOI: 10.1038/srep31486

 

Source: New Jersey Institute of Technology. “Global warming’s next surprise: Saltier beaches.” ScienceDaily. ScienceDaily, 11 August 2016. <www.sciencedaily.com/releases/2016/08/160811142647.htm>.

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Cancer cells kill blood vessel cells so that they can slip through the vascular wall, form metastases

Date:
August 10, 2016

Source:
Max-Planck-Gesellschaft

Summary:
Many cancers only become a mortal danger if they form metastases elsewhere in the body. Now researchers have discovered that cancer cells kill blood vessel cells so that they can slip through the vascular wall and form metastases.

 

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The most common cause of cancer deaths is not the primary tumor itself but metastases that subsequently form.
Credit: © mybaitshop / Fotolia

 

 

Many cancers only become a mortal danger if they form metastases elsewhere in the body. Such secondary tumours are formed when individual cells break away from the main tumour and travel through the bloodstream to distant areas of the body. To do so, they have to pass through the walls of small blood vessels. Scientists from the Max Planck Institute for Heart and Lung Research in Bad Nauheim and Goethe University Frankfurt have now shown that tumour cells kill specific cells in the vascular wall. This enables them to leave the vessels and establish metastases, a process facilitated by a molecule called DR6.

The most common cause of cancer deaths is not the primary tumour itself but metastases that subsequently form. Most tumour cells spread via the bloodstream. To do so, individual tumour cells have to enter blood vessels and leave the bloodstream again at remote locations.

Together with scientists at the universities of Cologne and Heidelberg, the Research Group led by Stefan Offermanns, Director of the Department of Pharmacology at the Max Planck Institute for Heart and Lung Research and professor at Goethe University Frankfurt, has now succeeded in clarifying the underlying mechanism. The researchers, working with cell cultures, first observed how individual tumour cells kill specific cells in the vascular wall, called endothelial cells. This process, known as necroptosis, enabled cancer cells to overcome an endothelial cell layer in the laboratory. “We were then able to show in studies on mice that the same process occurs in living organisms,” says Boris Strilic, first author of the study.

The scientists also found that endothelial cells themselves give the signal for their own death: To do this, the vascular wall cells have a receptor molecule called Death Receptor 6 (DR6) on their surface. “When a cancer cell comes into contact with it, a protein on the cell’s surface, known as APP, activates DR6. This marks the start of the cancer cells’ attack on the vascular wall, which culminates in the necroptosis of wall cells,” Strilic explains.

Death Receptor in the cell membrane

The Max Planck researchers then showed that less necroptosis of endothelial cells and less metastasis occur in genetically modified animals in which Death Receptor 6 is disabled. “This effect was also found after a blockade of DR6 or the cancer-cell protein APP, thus confirming our previous observations,” Strilic says.

It is still not entirely clear whether the cancer cells migrate directly through the resulting gap in the vascular wall or whether there is an indirect effect: “We have evidence that many more molecules are released when the vascular wall cell dies and that they render the surrounding area more permeable to cancer cells,” says Offermanns.

“This mechanism could be a promising starting point for treatments to prevent the formation of metastases,” says Offermanns. First, however, it must be determined whether a blockade of DR6 triggers unwanted side effects. It must also be determined to what extent the observations can be transferred to humans.


Story Source:

The above post is reprinted from materials provided by Max-Planck-Gesellschaft. Note: Content may be edited for style and length.


Journal Reference:

  1. Boris Strilic, Lida Yang, Julián Albarrán-Juárez, Laurens Wachsmuth, Kang Han, Ulrike C. Müller, Manolis Pasparakis, Stefan Offermanns.Tumour-cell-induced endothelial cell necroptosis via death receptor 6 promotes metastasis. Nature, 2016; 536 (7615): 215 DOI:10.1038/nature19076

 

Source: Max-Planck-Gesellschaft. “Loophole for cancer cells found: Cancer cells kill blood vessel cells so that they can slip through the vascular wall, form metastases.” ScienceDaily. ScienceDaily, 10 August 2016. <www.sciencedaily.com/releases/2016/08/160810104248.htm>.

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Women in parts of Africa without dairy farming far less likely to develop osteoporosis than women in dairy farming areas of Africa, research shows

Date:
August 9, 2016

Source:
University of North Texas

Summary:
An evolutionary historian has determined that the region of origin of ancestors contributes to descendants’ risk of developing certain medical conditions.

 

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The medical community “needs to look at hereditary history and not put all races in a few categories,” say authors of a new report.
Credit: © filipefrazao / Fotolia

 

 

Research from a University of North Texas historian supports the idea that the nation and region of origin of your ancestors contributes to your risk of developing, or not developing, a growing list of medical conditions.

Constance Hilliard, professor of history specializing in pre-colonial African history, discovered that West African women living in regions infested by tsetse flies, which attack cattle and so prevent dairy farming, have a much lower rate of postmenopausal hip fractures caused by osteoporosis than their East African peers. The West African women, however, have diets low in calcium, which prevents bone loss that leads to osteoporosis. The research was recently published in the Bonekey edition of Nature.

Using data for women from 40 nations, including Cameroon and Nigeria in West Africa and Kenya in East Africa, on the amount of hip fractures, annual dairy consumption and prevalence of a genetic mutation that leads to lactose intolerance, Hilliard determined that the West African women were “essentially immune” to osteoporosis, with only three hip fractures per 100,000 people.

The East African women, who were living in regions with dairy farming, suffered 243 hip fractures — still far lower than the rate for U.S. women of 595 fractures, and residents of other nations with much larger dairy farming and much larger calcium consumption.

Both ethnic groups, Hilliard notes, lack the genetic alleles, or variations, needed to process the lactose in milk, and also have little access to other foods high in calcium.

“Osteoporosis appears to have entered the human genome approximately 10,000 years ago with the advent of dairy farming. In a genetic trade off, those humans who received evolutionary advantages through expansion of the food supply with readily available dairy protein might also have genetically adapted their own calcium homeostasis in ways that disadvantage bone strength,” Hilliard said.

She said the medical community “needs to look at hereditary history and not put all races in a few categories.”

“You may think those in certain races look the same, but their genetics are not necessarily the same,” she said. “For example, during my research, I found out that people in India were categorized as Asians and had high rates of osteoporosis, despite living in a dairy culture that considers cows as sacred and not to be slaughtered.”

The findings, she said, resolve a longstanding paradox in the public health community: While African-Americans are generally low consumers of dietary calcium, as compared to other racial and ethnic groups in the U.S., they are also at far less risk for developing osteoporosis than the other groups.

“Eighty-five percent of European populations have the genetic variant that allow them to drink milk, but Americans of European descent have higher rates of osteoporosis,” Hilliard said.

She is now researching androgen-resistant prostate cancer, the often fatal form of this cancer, in African Americans. African Americans have 2.5 times the rate of this form of cancer than males of European descent.

“Past research has determined a powerful correlation between cancer and high dairy consumption, but African Americans are getting prostate cancer with lower levels of dairy consumption,” she says.


Story Source:

The above post is reprinted from materials provided by University of North Texas. Note: Content may be edited for style and length.


Journal Reference:

  1. Constance B Hilliard. High osteoporosis risk among East Africans linked to lactase persistence genotype. BoneKEy Reports, 2016; 5: 803 DOI: 10.1038/bonekey.2016.30

 

Source: University of North Texas. “Heredity explains African-American paradox, researcher says: Women in parts of Africa without dairy farming far less likely to develop osteoporosis than women in dairy farming areas of Africa, research shows.” ScienceDaily. ScienceDaily, 9 August 2016. <www.sciencedaily.com/releases/2016/08/160809145300.htm>.

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Modifier appears to dissolve crystals of the most common kidney stone

Date:
August 8, 2016

Source:
University of Houston

Summary:
Researchers have found evidence that a natural fruit extract is capable of dissolving calcium oxalate crystals, the most common component of human kidney stones. This finding could lead to the first advance in the treatment of calcium oxalate stones in 30 years.

 

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Engineer Jeffrey Rimer and collaborators have discovered a new molecule that has the potential to be a more effective inhibitor of kidney stone formation.
Credit: University of Houston

 

 

Researchers have found evidence that a natural fruit extract is capable of dissolving calcium oxalate crystals, the most common component of human kidney stones. This finding could lead to the first advance in the treatment of calcium oxalate stones in 30 years.

Jeffrey Rimer, associate professor of chemical engineering at the University of Houston, was lead author of the study, published Aug. 8 in the online edition of Nature. The work offers the first evidence that the compound hydroxycitrate (HCA) is an effective inhibitor of calcium oxalate crystal growth that, under certain conditions, is actually able to dissolve these crystals. Researchers also explain how it works.

The findings are the result of a combination of experimental studies, computational studies and human studies, Rimer said.

Kidney stones are small, hard mineral deposits that form inside the kidneys, affecting up to 12 percent of men and seven percent of women. High blood pressure, diabetes and obesity can increase the risk, and the reported incidence is on the rise.

Preventive treatment has not changed much over the last three decades. Doctors tell patients who are at risk of developing stones to drink lots of water and avoid foods rich in oxalate, such as rhubarb, okra, spinach and almonds. They often recommend taking citrate (CA), in the form of potassium citrate, a supplement that can slow crystal growth, but some people are unable to tolerate the side effects.

The project grew out of preliminary work done by collaborator John Asplin, a nephrologist at Litholink Corporation, who suggested HCA as a possible treatment. HCA is chemically similar to CA and is also available as a dietary supplement.

“HCA shows promise as a potential therapy to prevent kidney stones,” the researchers wrote. “HCA may be preferred as a therapy over CA (potassium citrate).”

In addition to Rimer and Asplin, authors on the paper include Giannis Mpourmpakis and his graduate student, Michael G. Taylor, of the University of Pittsburgh; Ignacio Granja of Litholink Corporation, and Jihae Chung, a UH graduate student working in Rimer’s lab.

The head-to-head studies of CA and HCA determined that while both compounds inhibit the growth of calcium oxalate crystals, HCA was more potent and displayed unique qualities that are advantageous for the development of new therapies.

The team of researchers then used atomic force microscopy, or AFM, to study interactions between the crystals, CA and HCA under realistic growth conditions. According to Rimer, the technique allowed them to record crystal growth in real time with near-molecular resolution.

Chung noted that the AFM images recorded the crystal actually shrinking when exposed to specific concentrations of HCA. Rimer suspected the initial finding was an abnormality, as it is rare to see a crystal actually dissolve in highly supersaturated growth solutions. The most effective inhibitors reported in the literature simply stop the crystal from growing.

It turned out that Chung’s initial finding was correct. Once they confirmed it is possible to dissolve crystals in supersaturated solutions, researchers then looked at reasons to explain why that happened.

Mpourmpakis and Taylor applied density functional theory (DFT) — a highly accurate computational method used to study the structure and properties of materials — to address how HCA and CA bind to calcium and to calcium oxalate crystals. They discovered HCA formed a stronger bond with crystal surfaces, inducing a strain that is seemingly relieved by the release of calcium and oxalate, leading to crystal dissolution.

HCA was also tested in human subjects, as seven people took the supplement for three days, allowing researchers to determine that HCA is excreted through urine, a requirement for the supplement to work as a treatment.

While Rimer said the research established the groundwork to design an effective drug, questions remain. Long-term safety, dosage and additional human trials are needed, he said.

“But our initial findings are very promising,” he said. “If it works in vivo, similar to our trials in the laboratory, HCA has the potential to reduce the incidence rate of people with chronic kidney stone disease.”


Story Source:

The above post is reprinted from materials provided by University of Houston. The original item was written by Jeannie Kever. Note: Content may be edited for style and length.


Journal Reference:

  1. Jihae Chung, Ignacio Granja, Michael G. Taylor, Giannis Mpourmpakis, John R. Asplin, Jeffrey D. Rimer. Molecular modifiers reveal a mechanism of pathological crystal growth inhibition. Nature, 2016; 1 DOI: 10.1038/nature19062

 

Source: University of Houston. “Researchers propose new treatment to prevent kidney stones: Modifier appears to dissolve crystals of the most common kidney stone.” ScienceDaily. ScienceDaily, 8 August 2016. <www.sciencedaily.com/releases/2016/08/160808115447.htm>.

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Pluripotency factor primes genes involved in differentiation

Date:
August 4, 2016

Source:
Sanford-Burnham Prebys Medical Discovery Institute

Summary:
Scientists have made a major advance in understanding how the cells of an organism, which all contain the same genetic information, come to be so diverse. A study shows that a protein called OCT4 narrows down the range of cell types that stem cells can become. The findings could impact efforts to produce specific types of cells for future therapies to treat a broad range of diseases.

 

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Fluorescence microscopic view of human skin cells (stock image).
Credit: © Vshyukova / Fotolia

 

 

Scientists at Sanford Burnham Prebys Medical Discovery Institute (SBP) have made a major advance in understanding how the cells of an organism, which all contain the same genetic information, come to be so diverse. A study published today in Molecular Cell shows that a protein called OCT4 narrows down the range of cell types that stem cells can become. The findings could impact efforts to produce specific types of cells for future therapies to treat a broad range of diseases, as well as aid the understanding of which cells are affected by drugs that influence cell specialization.

“We found that the stem cell-specific protein OCT4 primes certain genes that, when activated, cause the cell to differentiate, or become more specialized,” said Laszlo Nagy, M.D., Ph.D., professor and director of the Genomic Control of Metabolism Program and senior author of the study. “This priming customizes stem cells’ responses to signals that induce differentiation and makes the underlying genetic process more efficient.”

Differentiation matters

As an organism — such as a human — develops from its simplest, earliest form into maturity, its cells transition from a highly flexible state — stem cells — to more specialized types that make up its tissues. Many labs are trying to recapitulate this process to generate specific types of cells that could be transplanted into patients to treat disease. For example, pancreatic beta cells could treat diabetes, and neurons that produce dopamine could treat Parkinson’s.

What OCT4 does

OCT4 is a transcription factor — a protein that regulates gene activity — that maintains stem cells’ ability to give rise to any tissue in the body. OCT4 works by sitting on DNA and recruiting factors that either help initiate or repress the reading of specific genes.

The new study shows that, at certain genes, OCT4 also collaborates with transcription factors that are activated by external signals, such as the retinoic acid (vitamin A) receptor (RAR) and beta-catenin, to turn on their respective genes. Vitamin A converts stem cells to neuronal precursors, and activation of beta-catenin by Wnt can either support pluripotency or promote non-neural differentiation, depending on what other signals are present. Recruitment of these factors ‘primes’ a subset of the genes that the signal-responsive factors can activate.

The big picture

“Our findings suggest a general principle for how the same differentiation signal induces distinct transitions in various types of cells,” added Nagy. “Whereas in stem cells, OCT4 recruits the RAR to neuronal genes, in bone marrow cells, another transcription factor would recruit RAR to genes for the granulocyte program. Which factors determine the effects of differentiation signals in bone marrow cells — and other cell types — remains to be determined.”

Next steps

“In a sense, we’ve found the code for stem cells that links the input — signals like vitamin A and Wnt — to the output — cell type,” said Nagy. “Now we plan to explore whether other transcription factors behave similarly to OCT4 — that is, to find the code in more mature cell types.

“If other factors also have this dual function — both maintaining the current state and priming certain genes to respond to external signals — that would answer a key question in developmental biology and advance the field of stem cell research.”

This research was performed in collaboration with scientists at the University of Debrecen in Hungary, the University of Leicester in the United Kingdom, the Max Planck Institute for Molecular Genetics, the University of Würzburg and the Max Delbrück Center for Molecular Medicine in Germany, the Institut de Génomique in France, and Weill Cornell Medical College, and supported by grants from the Hungarian Scientific Research Fund, the Hungarian Brain Research Program, and the U.S. National Institutes of Health.


Story Source:

The above post is reprinted from materials provided by Sanford-Burnham Prebys Medical Discovery Institute. The original item was written by Jessica Moore. Note: Content may be edited for style and length.


Journal Reference:

  1. Zoltan Simandi, Attila Horvath, Lyndsey C. Wright, Ixchelt Cuaranta-Monroy, Isabella De Luca, Katalin Karolyi, Sascha Sauer, Jean-Francois Deleuze, Lorraine J. Gudas, Shaun M. Cowley, Laszlo Nagy. OCT4 Acts as an Integrator of Pluripotency and Signal-Induced Differentiation. Molecular Cell, 2016; DOI:10.1016/j.molcel.2016.06.039

 

Source: Sanford-Burnham Prebys Medical Discovery Institute. “Breakthrough in understanding how stem cells become specialized: Pluripotency factor primes genes involved in differentiation.” ScienceDaily. ScienceDaily, 4 August 2016. <www.sciencedaily.com/releases/2016/08/160804140503.htm>.

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Technology could lead to the development of neuromorphic computers

Date:
August 4, 2016

Source:
IBM Research

Summary:
Scientists have created randomly spiking neurons using phase-change materials to store and process data. This demonstration marks a significant step forward in the development of energy-efficient, ultra-dense integrated neuromorphic technologies for applications in cognitive computing.

 

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Phase-change neurons. A chip with large arrays of phase-change devices that store the state of artificial neuronal populations in their atomic configuration. In the photograph, individual devices are accessed by means of an array of probes to allow for precise characterization, modeling and interrogation. The tiny squares are contact pads that are used to access the nanometer-scale phase-change cells (not visible). The sharp probes touch the contact pads to change the phase configuration stored in the cells in response to the neuronal input. Each set of probes can access a population of 100 cells. The chip hosts only the phase-change devices that are the “heart” of the neurons. There are thousands to millions of these cells on one chip and we access them (in this particular photograph) by means of the sharp needles (probe card).
Credit: IBM Research

 

 

IBM scientists have created randomly spiking neurons using phase-change materials to store and process data. This demonstration marks a significant step forward in the development of energy-efficient, ultra-dense integrated neuromorphic technologies for applications in cognitive computing.

Inspired by the way the biological brain functions, scientists have theorized for decades that it should be possible to imitate the versatile computational capabilities of large populations of neurons. However, doing so at densities and with a power budget that would be comparable to those seen in biology has been a significant challenge, until now.

“We have been researching phase-change materials for memory applications for over a decade, and our progress in the past 24 months has been remarkable,” said IBM Fellow Evangelos Eleftheriou. “In this period, we have discovered and published new memory techniques, including projected memory, stored 3 bits per cell in phase-change memory for the first time, and now are demonstrating the powerful capabilities of phase-change-based artificial neurons, which can perform various computational primitives such as data-correlation detection and unsupervised learning at high speeds using very little energy.”

The results of this research are appearing today on the cover of the peer-reviewed journal Nature Nanotechnology.

The artificial neurons designed by IBM scientists in Zurich consist of phase-change materials, including germanium antimony telluride, which exhibit two stable states, an amorphous one (without a clearly defined structure) and a crystalline one (with structure). These materials are the basis of re-writable Blu-ray discs. However, the artificial neurons do not store digital information; they are analog, just like the synapses and neurons in our biological brain.

In the published demonstration, the team applied a series of electrical pulses to the artificial neurons, which resulted in the progressive crystallization of the phase-change material, ultimately causing the neuron to fire. In neuroscience, this function is known as the integrate-and-fire property of biological neurons. This is the foundation for event-based computation and, in principle, is similar to how our brain triggers a response when we touch something hot.

Exploiting this integrate-and-fire property, even a single neuron can be used to detect patterns and discover correlations in real-time streams of event-based data. For example, in the Internet of Things, sensors can collect and analyze volumes of weather data collected at the edge for faster forecasts. The artificial neurons could be used to detect patterns in financial transactions to find discrepancies or use data from social media to discover new cultural trends in real time. Large populations of these high-speed, low-energy nano-scale neurons could also be used in neuromorphic coprocessors with co-located memory and processing units.

IBM scientists have organized hundreds of artificial neurons into populations and used them to represent fast and complex signals. Moreover, the artificial neurons have been shown to sustain billions of switching cycles, which would correspond to multiple years of operation at an update frequency of 100 Hz. The energy required for each neuron update was less than five picojoule and the average power less than 120 microwatts — for comparison, 60 million microwatts power a 60 watt lightbulb.

“Populations of stochastic phase-change neurons, combined with other nanoscale computational elements such as artificial synapses, could be a key enabler for the creation of a new generation of extremely dense neuromorphic computing systems,” said Tomas Tuma, a co-author of the paper.

To read more about this research, please go to:https://www.ibm.com/blogs/research/2016/08/unsupervised-learning-artificial-neurons


Story Source:

The above post is reprinted from materials provided by IBM Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. Tomas Tuma, Angeliki Pantazi, Manuel Le Gallo, Abu Sebastian, Evangelos Eleftheriou. Stochastic phase-change neurons. Nature Nanotechnology, 2016; 11 (8): 693 DOI: 10.1038/nnano.2016.70

 

Source: IBM Research. “Phase-change device imitates the functionality of neurons: Technology could lead to the development of neuromorphic computers.” ScienceDaily. ScienceDaily, 4 August 2016. <www.sciencedaily.com/releases/2016/08/160804093327.htm>.

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Method to reinforce these materials could help make airplane frames lighter, more damage-resistant

Date:
August 3, 2016

Source:
Massachusetts Institute of Technology

Summary:
Aerospace engineers have designed carbon nanotube ‘stitches’ that strongly bind composites, which could produce lighter, more damage-resistant airplanes.

 

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MIT aerospace engineers have found a way to bond composite layers, producing a material that is substantially stronger and more resistant to damage than other advanced composites. The improvement may lead to stronger, lighter airplane parts.
Credit: Illustration: Christine Daniloff/MIT

 

 

The newest Airbus and Boeing passenger jets flying today are made primarily from advanced composite materials such as carbon fiber reinforced plastic — extremely light, durable materials that reduce the overall weight of the plane by as much as 20 percent compared to aluminum-bodied planes. Such lightweight airframes translate directly to fuel savings, which is a major point in advanced composites’ favor.

But composite materials are also surprisingly vulnerable: While aluminum can withstand relatively large impacts before cracking, the many layers in composites can break apart due to relatively small impacts — a drawback that is considered the material’s Achilles’ heel.

Now MIT aerospace engineers have found a way to bond composite layers in such a way that the resulting material is substantially stronger and more resistant to damage than other advanced composites. Their results are published this week in the journal Composites Science and Technology.

The researchers fastened the layers of composite materials together using carbon nanotubes — atom-thin rolls of carbon that, despite their microscopic stature, are incredibly strong. They embedded tiny “forests” of carbon nanotubes within a glue-like polymer matrix, then pressed the matrix between layers of carbon fiber composites. The nanotubes, resembling tiny, vertically-aligned stitches, worked themselves within the crevices of each composite layer, serving as a scaffold to hold the layers together.

In experiments to test the material’s strength, the team found that, compared with existing composite materials, the stitched composites were 30 percent stronger, withstanding greater forces before breaking apart.

Roberto Guzman, who led the work as an MIT postdoc in the Department of Aeronautics and Astronautics (AeroAstro), says the improvement may lead to stronger, lighter airplane parts — particularly those that require nails or bolts, which can crack conventional composites.

“More work needs to be done, but we are really positive that this will lead to stronger, lighter planes,” says Guzman, who is now a researcher at the IMDEA Materials Institute, in Spain. “That means a lot of fuel saved, which is great for the environment and for our pockets.”

The study’s co-authors include AeroAstro professor Brian Wardle and researchers from the Swedish aerospace and defense company Saab AB.

“Size matters”

Today’s composite materials are composed of layers, or plies, of horizontal carbon fibers, held together by a polymer glue, which Wardle describes as “a very, very weak, problematic area.” Attempts to strengthen this glue region include Z-pinning and 3-D weaving — methods that involve pinning or weaving bundles of carbon fibers through composite layers, similar to pushing nails through plywood, or thread through fabric.

“A stitch or nail is thousands of times bigger than carbon fibers,” Wardle says. “So when you drive them through the composite, you break thousands of carbon fibers and damage the composite.”

Carbon nanotubes, by contrast, are about 10 nanometers in diameter — nearly a million times smaller than the carbon fibers.

“Size matters, because we’re able to put these nanotubes in without disturbing the larger carbon fibers, and that’s what maintains the composite’s strength,” Wardle says. “What helps us enhance strength is that carbon nanotubes have 1,000 times more surface area than carbon fibers, which lets them bond better with the polymer matrix.”

Stacking up the competition

Guzman and Wardle came up with a technique to integrate a scaffold of carbon nanotubes within the polymer glue. They first grew a forest of vertically-aligned carbon nanotubes, following a procedure that Wardle’s group previously developed. They then transferred the forest onto a sticky, uncured composite layer and repeated the process to generate a stack of 16 composite plies — a typical composite laminate makeup — with carbon nanotubes glued between each layer.

To test the material’s strength, the team performed a tension-bearing test — a standard test used to size aerospace parts — where the researchers put a bolt through a hole in the composite, then ripped it out. While existing composites typically break under such tension, the team found the stitched composites were stronger, able to withstand 30 percent more force before cracking.

The researchers also performed an open-hole compression test, applying force to squeeze the bolt hole shut. In that case, the stitched composite withstood 14 percent more force before breaking, compared to existing composites.

“The strength enhancements suggest this material will be more resistant to any type of damaging events or features,” Wardle says. “And since the majority of the newest planes are more than 50 percent composite by weight, improving these state-of-the art composites has very positive implications for aircraft structural performance.”


Story Source:

The above post is reprinted from materials provided by Massachusetts Institute of Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. R. Guzman de Villoria, P. Hallander, L. Ydrefors, P. Nordin, B.L. Wardle.In-plane strength enhancement of laminated composites via aligned carbon nanotube interlaminar reinforcement. Composites Science and Technology, 2016; 133: 33 DOI:10.1016/j.compscitech.2016.07.006

 

Source: Massachusetts Institute of Technology. “Carbon nanotube ‘stitches’ make stronger, lighter composites: Method to reinforce these materials could help make airplane frames lighter, more damage-resistant.” ScienceDaily. ScienceDaily, 3 August 2016. <www.sciencedaily.com/releases/2016/08/160803111753.htm>.

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Date:
August 2, 2016

Source:
University of Utah

Summary:
Anthropologists have counted the number of carbon-dated artifacts at archaeological sites and concluded that a population boom and scarce food explain why people in eastern North America domesticated plants for the first time on the continent about 5,000 years ago.

 

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This map shows the area covered by a new University of Utah study that concludes a population boom and resulting scarcity of wild foods are what caused early people in eastern North America to domesticate wild food plants for the first time on the continent starting about 5,000 year ago. The triangles and names represent archaeological sites previously identified as locations where one or more of the these plants first were domesticated: squash, sunflower, marshelder and pitseed goosefoot, a relative of quinoa. The small circles are sites where radiocarbon-dated artifacts have been found, with a single circle often representing many dated artifacts. The study area includes much of eastern North America inland from the Atlantic and Gulf coasts.
Credit: Elic Weitzel, University of Utah

 

 

University of Utah anthropologists counted the number of carbon-dated artifacts at archaeological sites and concluded that a population boom and scarce food explain why people in eastern North America domesticated plants for the first time on the continent about 5,000 years ago.

“Domesticated plants and animals are part of our everyday lives, so much so that we take them for granted,” says Brian Codding, senior author of the study published online August 2 by the British journal Royal Society Open Science. “But they represent a very unique thing in human history. They allowed for large numbers of people to live in one place. That ultimately set the stage for the emergence of civilization.”

Graduate student Elic Weitzel, the study’s first author, adds: “For most of human history, people lived off wild foods — whatever they could hunt or gather. It’s only relatively recently that people made this switch to a very different method of acquiring their food. It’s important to understand why that transition happened.”

The study dealt not with a full-fledged agricultural economy, but with the earlier step of domestication, when early people in eastern North America first started growing plants they had harvested in the wild, namely, squash, sunflower, marshelder and a chenopod named pitseed goosefoot, a pseudocereal grain closely related to quinoa.

Codding, an assistant professor of anthropology, says at least 11 plant domestication events have been identified in world history, starting with wheat about 11,500 years ago in the Middle East. The eastern North American plant domestication event, which began around 5,000 years ago, was the ninth of those 11 events and came after a population boom 6,900 to 5,200 years ago, he adds.

For many years, two competing theories have sought to explain the cause of plant domestication in eastern North America: First, population growth and resulting food scarcity prompted people to grow foods on which they already foraged. Second, a theory called “niche construction” or “ecosystem engineering” that basically says intentional experimentation and management during times of plenty — and not immediate necessity — led people to manage and manipulate wild plants to increase their food supply.

“We argue that human populations significantly increased prior to plant domestication in eastern North America, suggesting that people are driven to domestication when populations outstrip the supply of wild foods,” Weitzel says.

“The transition to domesticating food allowed human populations to increase drastically around the world and made our modern way of life possible,” he adds. “People start living near the fields. Whenever you’ve got sedentary communities, they start to expand. Villages expand into cities. Once you have that, you have all sorts of social changes. We really don’t see state-level society until domestication occurs.”

When early North Americans first domesticated crops

The region of eastern North America covered by the study includes most of Missouri, Illinois, Indiana, Ohio, West Virginia, Kentucky, Tennessee and Arkansas, and portions of Oklahoma, Kansas, Iowa, Virginia, North Carolina, South Carolina, Georgia, Mississippi and Louisiana.

“This is the region where these plant foods were domesticated from their wild variants,” Weitzel says. “Everywhere else in North America, crops were imported from elsewhere,” particularly Mexico and Central America.

Four indigenous plant species constitute what scientists call the Eastern Agricultural Complex, which people began to domesticate about 5,000 years ago.

Previous research shows specific domestication dates were 5,025 years ago for squash at an archaeological site named Phillips Spring in Missouri, 4,840 years ago for sunflower seeds domesticated at Hayes in Tennessee, 4,400 years ago for marshelder at the Napoleon Hollow site in Illinois, and 3,800 years ago for pitseed goosefoot found in large quantities at Riverton, Illinois, along with squash, sunflower and marshelder.

Three more recent sites also have been found to contain evidence of domestication of all four species: Kentucky’s Cloudsplitter and Newt Kindigenash rockshelters, dated to 3,700 and 3,640 years ago, respectively, and the 3,400-year-old Marble Bluff site in Arkansas.

Sunflower and squash — including acorn and green and yellow summer squashes — remain important crops today, while marshelder and pitseed goosefoot are not (although the related quinoa is popular).

Deducing population swings from radiocarbon dates

“It’s really difficult to arrive at measures of prehistoric populations. So archaeologists have struggled for a long time coming up with some way of quantifying population levels when we don’t have historical records,” Weitzel says.

“People have looked at the number of sites through time, the number of artifacts through time and some of the best work has looked at the effects of population growth,” such as in the switch from a diet of tortoises to rabbits as population grew in the eastern Mediterranean during the past 50,000 years, he adds.

Codding says that in the past decade, archaeologists have expanded the use of radiocarbon-dates for artifacts to reconstruct prehistoric population histories. Weitzel says radiocarbon dates in the new study came from artifacts such as charcoal, nutshells and animal bones — all recorded in a database maintained by Canadian scientists.

The University of Utah anthropologists used these “summed radiocarbon dates” for 3,750 dated artifacts from eastern North America during the past 15,000 years.

“The assumption is that if you had more people, they left more stuff around that could be dated,” Weitzel says. “So if you have more people, you conceivably should have more radiocarbon dates.”

“We plotted the dates through time,” namely, the number of radiocarbon dates from artifacts in every 100-year period for the past 15,000 years, he adds.

The analysis indicated six periods of significant population increase or decrease during that time, including one during which population nearly doubled in eastern North America starting about 6,900 years ago and continuing apace until 5,200 years ago — not long before plant domestication began, Codding says.

Codding notes that even though plant domestication meant “these people were producing food to feed themselves and their families, they’re still hunting and foraging,” eating turtles, fish, water fowl and deer, among other animals.

The other theory

Weitzel says the concept of niche construction is that people were harvesting wild plants, and “were able to get more food from certain plants.” By manipulating the environment — such as transplanting wild plants or setting fires to create areas favorable for growth of wild food plants — they began “experimenting with these plants to see if they could grow them to be bigger or easier to collect and consume,” he adds. “That kind of experimentation then leads to domestication.”

Codding says: “The idea is that when times are good and people have plenty of food then they will experiment with plants. We say that doesn’t provide an explanation for plant domestication in eastern North America.” He believes the behavioral ecology explanation: increasing population and-or decreasing wild food resources led to plant domestication.


Story Source:

The above post is reprinted from materials provided by University of Utah.Note: Materials may be edited for content and length.

 

Source: University of Utah. “Population boom preceded early farming.” ScienceDaily. ScienceDaily, 2 August 2016. <www.sciencedaily.com/releases/2016/08/160802104526.htm>.

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Date:
August 1, 2016

Source:
Duke University

Summary:
A new study could explain why DNA and not RNA, its older chemical cousin, is the repository of genetic information. The DNA double helix is a more forgiving molecule that can contort itself into different shapes to absorb chemical damage to the basic building blocks — A, G, C and T — of genetic code. In contrast, when RNA is in the form of a double helix, it is so rigid that rather than accommodating damaged bases, it falls apart.

 

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The DNA double helix (shown on the left) can contort itself into different shapes to absorb chemical damage to the basic building blocks (A, G, C and T, depicted by a black dot) of genetic code. In contrast, an RNA double helix (shown on the right) is so rigid and unyielding that rather than accommodating damaged bases, it falls apart completely.
Credit: Huiqing Zhou, Duke University

 

 

A new study could explain why DNA and not RNA, its older chemical cousin, is the main repository of genetic information. The DNA double helix is a more forgiving molecule that can contort itself into different shapes to absorb chemical damage to the basic building blocks — A, G, C and T — of genetic code. In contrast, when RNA is in the form of a double helix it is so rigid and unyielding that rather than accommodating damaged bases, it falls apart completely.

The research, published August 1, 2016 in the journal Nature Structural and Molecular Biology, underscores the dynamic nature of the DNA double helix, which is central to maintaining the stability of the genome and warding off ailments like cancer and aging. The finding will likely rewrite textbook coverage of the difference between the two purveyors of genetic information, DNA and RNA.

“There is an amazing complexity built into these simple beautiful structures, whole new layers or dimensions that we have been blinded to because we didn’t have the tools to see them, until now,” said Hashim M. Al-Hashimi, Ph.D., senior author of the study and professor of biochemistry at Duke University School of Medicine.

DNA’s famous double helix is often depicted as a spiral staircase, with two long strands twisted around each other and steps composed of four chemical building blocks called bases. Each of these bases contain rings of carbon, along with various configurations of nitrogen, oxygen, and hydrogen. The arrangement of these atoms allow G to pair with C and A to pair with T, like interlocking gears in an elegant machine.

When Watson and Crick published their model of the DNA double helix in 1953, they predicted exactly how these pairs would fit together. Yet other researchers struggled to provide evidence of these so-called Watson-Crick base pairs. Then in 1959, a biochemist named Karst Hoogsteen took a picture of an A-T base pair that had a slightly skewed geometry, with one base rotated 180 degrees relative to the other. Since then, both Watson-Crick and Hoogsteen base pairs have been observed in still images of DNA.

Five years ago, Al-Hashimi and his team showed that base pairs constantly morph back and forth between Watson-Crick and the Hoogsteen configurations in the DNA double helix. Al-Hashimi says that Hoogsteen base pairs typically show up when DNA is bound up by a protein or damaged by chemical insults. The DNA goes back to its more straightforward pairing when it is released from the protein or has repaired the damage to its bases.

“DNA seems to use these Hoogsteen base pairs to add another dimension to its structure, morphing into different shapes to achieve added functionality inside the cell,” said Al-Hashimi.

Al-Hashimi and his team wanted to know if the same phenomenon might also be occurring when RNA, the middleman between DNA and proteins, formed a double helix. Because these shifts in base pairing involve the movement of molecules at an atomic level, they are difficult to detect by conventional methods. Therefore, Al-Hashimi’s graduate student Huiqing Zhou used a sophisticated imaging technique known as NMR relaxation dispersion to visualize these tiny changes. First, she designed two model double helices — one made of DNA and one made of RNA. Then, she used the NMR technique to track the flipping of individual G and A bases that make up the spiraling steps, pairing up according to Watson-Crick or Hoogsteen rules.

Prior studies indicated that at any given time, one percent of the bases in the DNA double helix were morphing into Hoogsteen base pairs. But when Zhou looked at the corresponding RNA double helix, she found absolutely no detectable movement; the base pairs were all frozen in place, stuck in the Watson-Crick configuration.

The researchers wondered if their model of RNA was an unusual exception or anomaly, so they designed a wide range of RNA molecules and tested them under a wide variety of conditions, but still none appeared to contort into the Hoogsteen configuration. They were concerned that the RNA might actually be forming Hoogsteen base pairs, but that they were happening so quickly that they weren’t able to catch them in the act. Zhou added a chemical known as a methyl group to a specific spot on the bases to block Watson-Crick base pairing, so the RNA would be trapped in the Hoogsteen configuration. She was surprised to find that rather than connecting through Hoogsteen base pairs, the two strands of RNA came apart near the damage site.

“In DNA this modification is a form of damage, and it can readily be absorbed by flipping the base and forming a Hoogsteen base pair. In contrast, the same modification severely disrupts the double helical structure of RNA,” said Zhou, who is lead author of the study.

The team believes that RNA doesn’t form Hoogsteen base pairs because its double helical structure (known as A-form) is more compressed than DNA’s (B-form) structure. As a result, RNA can’t flip one base without hitting another, or without moving around atoms, which would tear apart the helix.

“For something as fundamental as the double helix, it is amazing that we are discovering these basic properties so late in the game,” said Al-Hashimi. “We need to continue to zoom in to obtain a deeper understanding regarding these basic molecules of life.”


Story Source:

The above post is reprinted from materials provided by Duke University.Note: Materials may be edited for content and length.


Journal Reference:

  1. Huiqing Zhou, Isaac J Kimsey, Evgenia N Nikolova, Bharathwaj Sathyamoorthy, Gianmarc Grazioli, James McSally, Tianyu Bai, Christoph H Wunderlich, Christoph Kreutz, Ioan Andricioaei, Hashim M Al-Hashimi.m1A and m1G disrupt A-RNA structure through the intrinsic instability of Hoogsteen base pairs. Nature Structural & Molecular Biology, 2016; DOI: 10.1038/nsmb.3270

 

Source: Duke University. “DNA’s dynamic nature makes it well-suited to serve as the blueprint of life.” ScienceDaily. ScienceDaily, 1 August 2016. <www.sciencedaily.com/releases/2016/08/160801113823.htm>.

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ON TARGET is Going on Vacation Until After labor Day – See You in September

 

As Summer is here to stay for a while, even a newsletter needs some R&R. So as in year’s past, ON TARGET will take a month off for a breather. Of course, Target Health Inc. continues full-speed ahead as August is always one of our business months.

 

Target Health’s Business Development Guru Warren Pearlson Visits the Galapagos

 

Warren Pearlson, Director of Business Development, took the trip of a lifetime to the Galapagos Islands, the birthplace of Charles Darwin’s Theory of Evolution. Without this transformational theory, there would be no modern medicine,

 

The photo of the Giant Tortoise below was taken on Santa Cruz Island, Galapagos, Ecuador using a Nikon Coolpix s7000.

 

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Giant Tortoise ©Warren Pearlson

 

For more information about Target Health contact Warren Pearlson (212-681-2100 ext. 165). For additional information about software tools for paperless clinical trials, please also feel free to contact Dr. Jules T. Mitchel or Ms. Joyce Hays. The Target Health software tools are designed to partner with both CROs and Sponsors. Please visit the Target Health Website.

 

Joyce Hays, Founder and Editor in Chief of On Target

Jules Mitchel, Editor

 

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