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Category Archives: Science and Medical

Mobile Phone Brain Cancer Link Rejected

  Further reseaimagerch has been published suggesting there is no link between mobile phones and brain cancer.

The risk mobiles present has been much debated over the past 20 years as use of the phones has soared.

The latest study led by the Institute of Cancer Epidemiology in Denmark looked at more than 350,000 people with mobile phones over an 18-year period.

Researchers concluded users were at no greater risk than anyone else of developing brain cancer.

The findings, published on the British Medical Journal website, come after a series of studies have come to similar conclusions.

 
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Posted by on January 26, 2012 in Science and Medical

 

Butterfly Found To Be New Species, Because Of Its Mustache

           After nearly a century in the Natural History Museum collections, a new butterfly species has been discovered because of its mustache.

A new butterfly species from the dry Magdalena valleys of Colombia has been discovered among the three million butterfly specimens at the Natural History Museum in London by a butterfly curator. It lay undiscovered in the collection for 90 years, but only when the curator Blanca Huertas compared it with a recently found wild specimen was it identified as Splendeuptychia ackeryi, or Magdalena valley ringlet, whose distinguishing feature is unusually hairy mouthparts.

Blanca Huertas, butterfly curator at the Natural History Museum, who discovered and described the new species said: “The collections here at the Natural History Museum are a treasure trove to be explored. We have almost nine million butterflies and moths in our collections, a comprehensive example of the Earth’s diversity. But there are many new species still waiting to be discovered, both in museum collections and in the field.”

Huertas discovered the new species in the wild when she traveled, with two colleagues, on an expedition to a remote mountain in Colombia in 2005. The entomologists did not realize, however, that the butterfly they had seen in Colombia had not been named and described until they returned to the UK and studied the specimens in the Museum’s collections, dating from 1920.

Huertas continued: “Butterflies are a diverse group of insects with almost 20,000 known species, 40 per cent of which are in South America. We are working hard at the Museum with our current exhibitions and developments such as Butterfly Jungle opening this summer and the new Darwin Centre opening in September, to encourage a new generation of researchers. They can help us complete an inventory of the planet’s biodiversity before we lose more species unknown to science.”

The description of the new butterfly is published in the latest issue of Zootaxa.

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Posted by on January 20, 2012 in Science and Medical

 

Saving Dogs With Spinal Cord Injuries

  Dogs with spinal cord injuries may soon benefit from an experimental drug being tested by researchers at the University of California, San Francisco (UCSF) and Texas A&M College of Veterinary Medicine & Biomedical Sciences — work that they hope will one day help people with similar injuries.

Funded through a three-year, $750,000 grant from the U.S. Department of Defense, the drug to mitigate damage has already proven effective in mice at UCSF. Now the Texas team will test how it works in previously injured short-legged, long torso breeds of dog like dachshunds, beagles and corgis, who often suffer injuries when a disk in their back spontaneously ruptures, damaging the underlying spinal cord.

About 120 dogs a year that develop sudden onset hind limb paralysis after such injuries are brought to the Small Animal Hospital of Texas A&M University, where they receive surgical and medical treatment similar to that for human spinal cord injury. Now, researchers will test whether the new treatment works on some of these dogs, with their owners’ consent.

“It would be phenomenal if it works,” said Linda J. Noble-Haeusslein, PhD, a professor in the UCSF departments of Neurological Surgery and Physical Therapy and Rehabilitation Science who designed the intervention. “We are in a unique position of being able to treat a dog population where there are simply no current therapies that could effectively improve their hind limb function.”

The new treatment does not seek to regrow injured pathways in the spinal cord. Instead, it aims to mitigate damage secondary to the spinal cord injury. Most spinal cord injuries trigger a cascade of chemical reactions in the spinal cord that collectively damage nearby cells and pathways, contributing to functional deficits including hind limb function.

A few years ago, Noble and her UCSF colleague Zena Werb, PhD, showed how blocking the action of one protein found in the spinal cord of mammals can help mice recover from spinal cord injuries. This protein, called matrix metalloproteinase-9, can degrade pathways within the cord and cause local inflammation, leading to cell death.

The injured dogs offer a great opportunity to take the next step on this treatment because their injuries more closely mimic spontaneous human spinal cord injury and, as is the case with humans, no existing treatment has substantially reduced paralysis. Dog in medical device

Dog in medical device

Noble’s co-investigator on the new study, Jonathan Levine, DVM, an assistant professor in neurology at Texas A&M University, will treat the dogs through injections of a protein-blocking drug. He will then help the dogs through rehabilitation and assess their recovery. Ongoing studies at UCSF focus on further refining delivery of the drug so as to optimize recovery.

Other researchers have shown that movement can be preserved if as little as 18 percent to 20 percent of the nerve fiber tracts in the spinal cord remain intact.

If successful, the trials in injured dogs may lead to the development of similar treatments for people who suffer spinal cord injuries, Noble said. These are among the most expensive injuries: every person with an injured spinal cord costs the health care system millions of dollars over his or her lifetime.

Such costs often are overshadowed by the tragic and devastating personal price of the injuries, which dramatically alter lives and most often occur in younger people, with long lives in front of them. According to the National Spinal Cord Injury Statistical Center, based at the University of Alabama, Birmingham, most of the 12,000 Americans who suffer spinal cord injuries are between the ages of 16 and 30.

As of this year, some 265,000 people in the United States are living with such injuries, according to the national center. This includes many wounded soldiers who have returned home from war zones.

UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care.

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Posted by on January 20, 2012 in Science and Medical

 

Harp Seals On Thin Ice After 32 Years of Warming

   Warming in the North Atlantic over the last 32 years has significantly reduced winter sea ice cover in harp seal breeding grounds, resulting in sharply higher death rates among seal pups in recent years, according to a new Duke University-led study.

“The kind of mortality we’re seeing in eastern Canada is dramatic. Entire year-classes may be disappearing from the population in low ice years — essentially all of the pups die,” said David W. Johnston, research scientist at the Duke University Marine Lab. “It calls into question the resilience of the population.”

The study, recently published in the peer-reviewed journal PLoS ONE, is the first to show that seasonal sea ice cover in all four harp seal breeding regions in the North Atlantic has declined by up to 6 percent a decade since 1979, when satellite records of ice conditions in the region began.

Harp seals rely on stable winter sea ice as safe places to give birth and nurse their young until the pups can swim and hunt on their own. Female seals typically seek out the thickest, oldest ice packs in sub-Arctic waters each February and March, and have adapted to the spring melt by developing unusually short, 12-day nursing periods.

“As a species, they’re well suited to deal with natural short-term shifts in climate, but our research suggests they may not be well adapted to absorb the effects of short-term variability combined with longer-term climate change and other human influences such as hunting and by-catch,” Johnston said.

To assess the cumulative impacts of these factors, the researchers analyzed satellite images of winter ice from 1992 to 2010 in the Gulf of St. Lawrence — a major breeding region off Canada’s east coast — and compared them to yearly reports of dead seal pup strandings in the region. They also compared the stranding rates to recorded measurements of the relative strength of the North Atlantic Oscillation (NAO), a climate phenomenon that controls the intensity and track of westerly winds and storms and greatly affects winter weather and sea ice formation in the region. These analyses revealed that higher pup mortalities occurred in the Northwest Atlantic harp seal herd in years with lighter ice cover and when the NAO was weaker.

Analysis of older data revealed that NAO-related changes in seasonal ice cover may have contributed to major declines in seal populations on the east coast of Canada from 1950 to 1972, and to a period of steady recovery from 1973 to 2000.

“This clearly shows that harp seal populations across the Atlantic fluctuate pretty much in synch with NAO trends and associated winter ice conditions,” Johnston said. “But there’s a caveat. Regardless of NAO conditions, our models show that sea ice cover in all harp seal breeding regions in the North Atlantic have been declining by as much as 6 percent a decade over the study period. The losses in bad years outweigh the gains in good years.”

A key unanswered question, he added, is whether seals will be able to respond to the long-term trend by moving to other, more stable ice habitats.

Recent reports that some harp seals are whelping in new breeding grounds off East Greenland indicate some shifting may be taking place, but thousands still return each year to traditional breeding grounds in the Gulf of St. Lawrence or along the Front, off Newfoundland, regardless of ice conditions.

“There’s only so much ice out there, and declines in the quantity and quality of it across the region, coupled with the earlier arrival of spring ice breakup, is literally leaving these populations on thin ice,” Johnston said. “It may take years of good ice and steady population gains to make up for the heavy losses sustained during the recent string of bad ice years in eastern Canada.”

Co-authors of the study are doctoral student Matthew T. Bowers and research scientist Ari S. Friedlaender, both of Duke, and David M. Lavigne, science advisor at the International Fund for Animal Welfare, which funded the study.

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Posted by on January 20, 2012 in Science and Medical

 

The Path Less Traveled: Research Is Driving Solutions to Improve Unpaved Roads

A Kansas State University graduate student sees the unpaved road ahead, and it’s filled with biomaterial.


Wilson Smith, master’s student in civil engineering, Independence, Mo., is working with lignin, a plant-based sustainable material that can be added to improve the quality of unpaved roads throughout Kansas.

More than 70 percent of the 98,000 miles of roads in Kansas are unpaved, Smith said.

“One of the problems with unpaved roads is that they are made from loose granular soils with particles that are not bound to each other on the road surface,” Smith said. “This limits the speed of vehicles and often generates a lot of dust, denigrating the quality of the road.”

But possible solutions could come from lignin, a biomass product that is present in all plants, including wheat straw, sugar cane and corn stover. Lignin is a waste product from other industries, including the production of biofuel and paper. These industries take plant mass and use the process of hydrolysis to separate useful materials, including cellulose and hemicellulose, from lignin.

“What we’re trying to do is find new uses for this lignin co-product, which ties into sustainability,” Smith said.

Several properties make lignin a valuable material. It is adhesive when it becomes moist, making it good for binding soil particles together and providing cohesion. As a result, lignin works very well on unpaved roads by providing better support for vehicles and protecting the road from erosion.

Because Kansas is an agricultural state, lignin is an abundant resource and has the potential to improve unpaved roads, leading to less maintenance costs throughout the state, Smith said.

“Lignin can be extracted from many types of crop residue, and it can also be an extra source of income to farmers and the agricultural community if there is a demand for this crop residue,” Smith said. “Lignin is a sustainable product. It’s 100 percent nontoxic, unlike traditional soil stabilizers such as flash or cement, which do have some heavy materials in them that could contaminate soil.”

Smith is working under the direction of Dunja Peric, associate professor of civil engineering.

“Kansas is strategically positioned for using lignin to stabilize unpaved roads,” Peric said. “Kansas is located in the midst of the Great Plains, which is one of the largest wheat producing areas in the world. In addition, the construction of the nation’s first commercial-scale cellulosic ethanol plant has recently begun in Hugoton.”

For his research, Smith takes soil and mixes it with different amounts of water and lignin. He is testing five different lignin concentrations — 2 percent, 4 percent, 6 percent, 9 percent and 14 percent — to understand how different levels of lignin affect the soil cohesion and, consequently, road erosion.

Smith then lets the mixture dry in a controlled environment for different periods of time to understand how much it increases the strength of the samples. Other members of Peric’s research team have been testing the strength of lignin samples immediately after they are mixed rather than allowing them to dry.

Once the materials are dry, Smith uses a direct shear device to determine the strength of the different mixtures. The direct shear device simulates the stress that unpaved roads experience when cars and heavy machinery drive on them.

“When vehicles drive on unpaved roads, there is a lot of dust that is thrown into the air,” Smith said. “In addition, travel is impaired because of raveling and washboarding, which are forms of soil collapse on the top surface of the road. These are all things that can be mitigated by lignin because it holds the soil particles together and in place.”

Based on early results, the materials with lignin concentrations of 4 percent, 6 percent and 9 percent show the highest strength benefits. Smith will spend the spring semester further testing all of the different concentrations and how their strength develops with the amount of elapsed time.

“We want to get an exhaustive analysis of how the cohesion varies when you change the concentration of lignin, the water content and the compaction,” Smith said. “That will determine in the field, what percentage of lignin is the best concentration to stabilize the soil.”

Smith will give a research presentation titled “Feasibility of Using Lignin: Plant Derived Material for Stabilization of Unpaved Roads” at the Capitol Graduate Research Summit in Topeka in February.

 
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Posted by on January 19, 2012 in Science and Medical

 

Scientists Solve Mystery of Colorful Armchair Nanotubes

Armchair carbon nanotubes — so named for the “U”-shaped configuration of the atoms at their uncapped tips — are one-dimensional metals and have no band gap. This means electrons flow from one end to the other with little resistivity, the very property that may someday make armchair quantum wires possible.

The Rice researchers show armchair nanotubes absorb light like semiconductors. An electron is promoted from an immobile state to a conducting state by absorbing photons and leaving behind a positively charged “hole,” said Rice physicist Junichiro Kono. The new electron-hole pair forms an exciton, which has a neutral charge.

“The excitons are created by the absorption of a particular wavelength of light,” said graduate student and lead author Erik Hároz. “What your eye sees is the light that’s left over; the nanotubes take a portion of the visible spectrum out.” The diameter of the nanotube determines which parts of the visible spectrum are absorbed; this absorption accounts for the rainbow of colors seen among different batches of nanotubes.

Scientists have realized that gold and silver nanoparticles could be manipulated to reflect brilliant hues — a property that let artisans who had no notions of “nano” create stained glass windows for medieval cathedrals. Depending on their size, the particles absorbed and emitted light of particular colors due to a phenomenon known as plasma resonance.

In more recent times, researchers noticed semiconducting nanoparticles, also known as quantum dots, show colors determined by their size-dependent band gaps.

But plasma resonance happens at wavelengths outside the visible spectrum in metallic carbon nanotubes. And armchair nanotubes don’t have band gaps.

Kono’s lab ultimately determined that excitons are the source of color in batches of pure armchair nanotubes suspended in solution.

The results seem counterintuitive, Kono said, because excitons are characteristic of semiconductors, not metals. Kono is a professor of electrical and computer engineering and of physics and astronomy.

While armchair nanotubes don’t have band gaps, they do have a unique electronic structure that favors particular wavelengths for light absorption, he said.

“In armchair nanotubes, the conduction and valence bands touch each other,” Kono said. “The one-dimensionality, combined with its unique energy dispersion, makes it a metal. But the bands develop what’s called a van Hove singularity,” which appears as a peak in the density of states in a one-dimensional solid. “So there are lots of electronic states concentrated around this singularity.”

Exciton resonance tends to occur around these singularities when hit with light, and the stronger the resonance, the more distinguished the color. “It’s an unusual quality of these particular one-dimensional materials that these excitons can actually exist,” Hároz said. “In most metals, that’s not possible; there’s not enough Coulomb interaction between the electron and the hole for an exciton to be stable.”

The new paper follows on the heels of work by Kono and his team to create batches of pure single-walled carbon nanotubes through ultracentrifugation. In that process, nanotubes were spun in a mix of solutions with different densities up to 250,000 times the force of gravity. The tubes naturally gravitated toward separated solutions that matched their own densities to create a colorful “nano parfait.”

As a byproduct of their current work, the researchers proved their ability to produce purified armchair nanotubes from a variety of synthesis techniques. They now hope to extend their investigation of the optical properties of armchairs beyond visible light. “Ultimately, we’d like to make one collective spectrum that includes frequency ranges all the way from ultraviolet to terahertz,” Hároz said. “From that, we can know, optically, almost everything about these nanotubes.”

Co-authors of the paper include Robert Hauge, a distinguished faculty fellow in chemistry at Rice; Rice alumnus Benjamin Lu; and professors Pavel Nikolaev and Sivaram Arepalli of Sungkyunkwan University, Suwon, Korea.

The research was supported by the Department of Energy, the Robert A. Welch Foundation, the Air Force Research Laboratory and the World Class University Program at Sungkyunkwan University.

 
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Posted by on January 19, 2012 in Science and Medical