徽派三雕“木雕、石雕、砖雕”全国闻名,而昨日记者从徽派玉雕文化协会成立大会上了解到,徽派玉雕也拟申请省非物质文化遗产.
徽派玉雕起源于安徽凌家滩文化,凌家滩文化遗址大墓内随葬品以高规格玉器为主.据了解,徽派玉雕雏形形成于宋代,风格玲珑精细,善用光影,以线塑形.协会负责人表示,在全国各主要玉雕创作基地,60%的玉雕匠人和大师皆为安徽籍,所以在省文化厅和民政厅支持下,徽派玉雕文化协会昨日得以成立.目前协会正在筹备为徽派玉雕申请非物质文化遗产,做强徽派玉雕.(蒋楠楠)
The finding could provide a niche for developing antimalarial drugs and vaccines that prevent or treat the disease by cutting these communication networks.
Professor Alan Cowman, Dr Neta Regev-Rudzki, Dr Danny Wilson and colleagues from the Walter and Eliza Hall Institute's Infection and Immunity division, in collaboration with Professor Andrew Hill from the University of Melbourne's Bio21 Institute and Department of Biochemistry and Molecular Biology showed that malaria parasites are able to send out messages to communicate with other malaria parasites in the body. The study was published today in the journal Cell.
Professor Cowman said the researchers were shocked to discover that malaria parasites work in unison to enhance 'activation' into sexually mature forms that can be picked up by mosquitoes, which are the carriers of this deadly disease.
"When Neta showed me the data, I was absolutely amazed, I couldn't believe it," Professor Cowman said. "We repeated the experiments many times in many different ways before I really started to believe that these parasites were signalling to each other and communicating. But we came to appreciate why the malaria parasite really needs this mechanism -- it needs to know how many other parasites are in the human to sense when is the right time to activate into sexual forms that give it the best chance of being transmitted back to the mosquito."
Malaria kills about 700,000 people a year, mostly children aged under five and pregnant women. Every year, hundreds of millions of people are infected with the malaria parasite, Plasmodium, which is transmitted through mosquito bites. It is estimated that half the world's population is at risk of contracting malaria, with the disease being concentrated in tropical and subtropical regions including many of Australia's near neighbours.
Dr Regev-Rudzki said the malaria parasites inside red blood cells communicate by sending packages of DNA to each other during the blood stage of infection. "We showed that the parasites inside infected red blood cells can send little packets of information from one parasite to another, particularly in response to stress," she said.
The communication network is a social behaviour that has evolved to signal when the parasites should complete their lifecycle and be transmitted back to a mosquito, Dr Regev-Rudzki said. "Once they receive this information, they change their fate -- the signals tell the parasites to become sexual forms, which are the forms of the malaria parasite that can live and replicate in the mosquito, ensuring the parasites survives and is transmitted to another human."
Professor Cowman said he hopes to see the discovery pave the way to new antimalarial drugs or vaccines for preventing malaria. "This discovery has fundamentally changed our view of the malaria parasite and is a big step in understanding how the malaria parasite survives and is transmitted," he said. "The next step is to identify the molecules involved in this signalling process, and ways that we could block these communication networks to block the transmission of malaria from the human to the mosquito. That would be the ultimate goal."
This project was supported by the National Health and Medical Research Council of Australia, Howard Hughes Medical Institute and the Victorian Government.
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May 15, 2013 — Writing in Nature, a large international team led Dr Roman Gorbachev from The University of Manchester shows that, when graphene placed on top of insulating boron nitride, or 'white graphene', the electronic properties of graphene change dramatically revealing a pattern resembling a butterfly.
The pattern is referred to as the elusive Hofstadter butterfly that has been known in theory for many decades but never before observed in experiments.
Combining graphene with other materials in multiple-layered structures could lead to novel applications not yet explored by science or industry.
Graphene is the world's thinnest, strongest and most conductive material, and promises a vast range of diverse applications; from smartphones and ultrafast broadband to drug delivery and computer chips. It was first demonstrated at The University of Manchester in 2004.
Initial trials of consumer products involving graphene-based touch screens and batteries for mobile phones and composite materials for sports goods are being carried out by major multinational companies.
One of the most remarkable properties of graphene is its high conductivity -- thousands of times higher than copper. This is due to a very special pattern created by electrons that carry electricity in graphene. The carriers are called Dirac fermions and mimic massless relativistic particles called neutrinos, studies of which usually require huge facilities such as at CERN. The possibility to address similar physics in a desk-top experiment is one of the most renowned features of graphene.
Now the Manchester scientists have found a way to create multiple clones of Dirac fermions. Graphene is placed on top of boron nitride so that graphene's electrons can 'feel' individual boron and nitrogen atoms. Moving along this atomic 'washboard', electrons rearrange themselves once again producing multiple copies of the original Dirac fermions.
The researchers can create even more clones by applying a magnetic field. The clones produce an intricate pattern; the Hofstadter butterfly. It was first predicted by mathematician Douglas Hofstadter in 1976 and, despite many dedicated experimental efforts, no more than a blurred glimpse was reported before.
In addition to the described fundamental interest, the Manchester study proves that it is possible to modify properties of atomically-thin materials by placing them on top of each other. This can be useful, for example, for graphene applications such as ultra-fast photodetectors and transistors, providing a way to tweak its incredible properties.
Professor Andre Geim, Nobel Laureate and co-author of the paper, said: "Of course, it is nice to catch the beautiful 'butterfly' which elusiveness tormented physicists for generations.
"More importantly, this work shows that we are now able to build up a principally new kind of materials by stacking individual atomic planes in a desired sequence."
Dr Gorbachev added: "We prepared a set of different atomically-thin materials similar to graphene then stacked them on top of each other, one atomic plane at a time. Such artificial crystals would have been science fiction a few years ago. Now they are reality in our lab. One day you might find these structures in your gadgets."
Professor Geim added: "This is an important step beyond 'simple graphene'. We now build foundations for a new research area that seems richer and even more important than graphene itself."
The Manchester paper is collaboration that involved researchers from the University of Lancaster in the UK, Instituto de Ciencia de Materiales de Madrid in Spain and National High-Field Laboratory in Grenoble, France.
It will appear in Nature back to back with another paper reporting similar butterflies in two layers of graphene, which comes from a group of Dr Philip Kim, Columbia University.
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Scientists using images from NASA's Mars Reconnaissance Orbiter, or MRO, have estimated that the planet is bombarded by more than 200 small asteroids or bits of comets per year forming craters at least 12.8 feet (3.9 meters) across.
Researchers have identified 248 new impact sites on parts of the Martian surface in the past decade, using images from the spacecraft to determine when the craters appeared. The 200-per-year planetwide estimate is a calculation based on the number found in a systematic survey of a portion of the planet.
The University of Arizona's High Resolution Imaging Science Experiment, or HiRISE camera, took pictures of the fresh craters at sites where before and after images had been taken. This combination provided a new way to make direct measurements of the impact rate on Mars and will lead to better age estimates of recent features on Mars, some of which may have been the result of climate change.
"It's exciting to find these new craters right after they form," said Ingrid Daubar of the UA, lead author of the paper published online this month by the journal Icarus. "It reminds you Mars is an active planet, and we can study processes that are happening today."
These asteroids or comet fragments typically are no more than 3 to 6 feet (1 to 2 meters) in diameter. Space rocks too small to reach the ground on Earth cause craters on Mars because the Red Planet has a much thinner atmosphere.
HiRISE targeted places where dark spots had appeared during the time between images taken by the spacecraft's Context Camera, or CTX, or cameras on other orbiters. The new estimate of cratering rate is based on a portion of the 248 new craters detected. If comes from a systematic check of a dusty fraction of the planet with CTX since late 2006.
The impacts disturb the dust, creating noticeable blast zones. In this part of the research, 44 fresh impact sites were identified.
The meteor over Chelyabinsk, Russia, in February was about 10 times bigger than the objects that dug the fresh Martian craters.
Estimates of the rate at which new craters appear serve as scientists' best yardstick for estimating the ages of exposed landscape surfaces on Mars and other worlds.
Daubar and co-authors calculated a rate for how frequently new craters at least 12.8 feet (3.9 meters) in diameter are excavated. The rate is equivalent to an average of one each year on each area of the Martian surface roughly the size of the U.S. state of Texas. Earlier estimates pegged the cratering rate at three to 10 times more craters per year. They were based on studies of craters on the moon and the ages of lunar rocks collected during NASA's Apollo missions in the late 1960s and early 1970s.
"Mars now has the best-known current rate of cratering in the solar system," said UA's HiRISE Principal Investigator Alfred McEwen, a co-author on the paper.
MRO has been examining Mars with six instruments since 2006. Daubar is an imaging targeting specialist who has been on the HiRISE uplink operation s team from the very beginning. She is also a graduate student in the UA's department of planetary science and plans on graduating with her doctorate in spring 2014.
"There are five of us who help plan the images that HiRISE will take over a two-week cycle," she explained. "We work with science team members across the world to understand their science goals, help select the image targets and compile the commands for the spacecraft and the camera."
"The longevity of this mission is providing wonderful opportunities for investigating changes on Mars," said MRO Deputy Project Scientist Leslie Tamppari of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
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May 15, 2013 — When the brain's primary "learning center" is damaged, complex new neural circuits arise to compensate for the lost function, say life scientists from UCLA and Australia who have pinpointed the regions of the brain involved in creating those alternate pathways -- often far from the damaged site.
The research, conducted by UCLA's Michael Fanselow and Moriel Zelikowsky in collaboration with Bryce Vissel, a group leader of the neuroscience research program at Sydney's Garvan Institute of Medical Research, appears this week in the early online edition of the Proceedings of the National Academy of Sciences.
The researchers found that parts of the prefrontal cortex take over when the hippocampus, the brain's key center of learning and memory formation, is disabled. Their breakthrough discovery, the first demonstration of such neural-circuit plasticity, could potentially help scientists develop new treatments for Alzheimer's disease, stroke and other conditions involving damage to the brain.
For the study, Fanselow and Zelikowsky conducted laboratory experiments with rats showing that the rodents were able to learn new tasks even after damage to the hippocampus. While the rats needed more training than they would have normally, they nonetheless learned from their experiences -- a surprising finding.
"I expect that the brain probably has to be trained through experience," said Fanselow, a professor of psychology and member of the UCLA Brain Research Institute, who was the study's senior author. "In this case, we gave animals a problem to solve."
After discovering the rats could, in fact, learn to solve problems, Zelikowsky, a graduate student in Fanselow's laboratory, traveled to Australia, where she worked with Vissel to analyze the anatomy of the changes that had taken place in the rats' brains. Their analysis identified significant functional changes in two specific regions of the prefrontal cortex.
"Interestingly, previous studies had shown that these prefrontal cortex regions also light up in the brains of Alzheimer's patients, suggesting that similar compensatory circuits develop in people," Vissel said. "While it's probable that the brains of Alzheimer's sufferers are already compensating for damage, this discovery has significant potential for extending that compensation and improving the lives of many."
The hippocampus, a seahorse-shaped structure where memories are formed in the brain, plays critical roles in processing, storing and recalling information. The hippocampus is highly susceptible to damage through stroke or lack of oxygen and is critically inolved in Alzheimer's disease, Fanselow said.
"Until now, we've been trying to figure out how to stimulate repair within the hippocampus," he said. "Now we can see other structures stepping in and whole new brain circuits coming into being."
Zelikowsky said she found it interesting that sub-regions in the prefrontal cortex compensated in different ways, with one sub-region -- the infralimbic cortex -- silencing its activity and another sub-region -- the prelimbic cortex -- increasing its activity.
"If we're going to harness this kind of plasticity to help stroke victims or people with Alzheimer's," she said, "we first have to understand exactly how to differentially enhance and silence function, either behaviorally or pharmacologically. It's clearly important not to enhance all areas. The brain works by silencing and activating different populations of neurons. To form memories, you have to filter out what's important and what's not."
Complex behavior always involves multiple parts of the brain communicating with one another, with one region's message affecting how another region will respond, Fanselow noted. These molecular changes produce our memories, feelings and actions.
"The brain is heavily interconnected -- you can get from any neuron in the brain to any other neuron via about six synaptic connections," he said. "So there are many alternate pathways the brain can use, but it normally doesn't use them unless it's forced to. Once we understand how the brain makes these decisions, then we're in a position to encourage pathways to take over when they need to, especially in the case of brain damage.
"Behavior creates molecular changes in the brain; if we know the molecular changes we want to bring about, then we can try to facilitate those changes to occur through behavior and drug therapy," he added. I think that's the best alternative we have. Future treatments are not going to be all behavioral or all pharmacological, but a combination of both."
Fanselow and Vissel have worked closely over the last several years. For more information on Fanselow's research, visit the Fanselow Lab website. For more on the Garvan Institute of Medical Research, visit their website.
The research was funded by the National Institute of Mental Health (grant MH 62122), part of the National Institutes of Health, and by the National Science Foundation (EAPSI award 0914307 to Zelikowsky).
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Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
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In addition to changing HDL from "good" to "bad," the inhalation of emissions activates other components of oxidation, the early cell and tissue damage that causes inflammation, leading to hardening of the arteries, according to the research team, which included scientists from UCLA and other institutions.
The findings of this early study, done in mice, are available in the online edition of the journal Arteriosclerosis, Thrombosis and Vascular Biology, a publication of the American Heart Association, and will appear in the journal's June print edition.
Emission particles such as those from vehicles are major pollutants in urban settings. These particles are coated in chemicals that are sensitive to free radicals, which have been known to cause oxidation. The mechanism behind how this leads to atherosclerosis, however, has not been well understood.
In the study, the researchers found that after two weeks of exposure to vehicle emissions, mice showed oxidative damage in the blood and liver -- damage that was not reversed after a subsequent week of receiving filtered air. Altered HDL cholesterol may play a key role in this damaging process, they said.
"This is the first study showing that air pollutants promote the development of dysfunctional, pro-oxidative HDL cholesterol and the activation of an internal oxidation pathway, which may be one of the mechanisms in how air pollution can exacerbate clogged arteries that lead to heart disease and stroke," said senior author Dr. Jesus Araujo, an associate professor of medicine and director of environmental cardiology at the David Geffen School of Medicine at UCLA.
For the study, one group of mice was exposed to vehicle emissions for two weeks and then filtered air for one week, a second was exposed to two weeks of emissions with no filtered air, and a third was exposed to only clean, filtered air for two weeks. This part of the collaborative research took place at the Northlake Exposure Facility at the University of Washington, headed by study author Michael E. Rosenfeld.
"The biggest surprise was finding that after two weeks of exposure to vehicle emissions, one week of breathing clean filtered air was not enough to reverse the damage," said Rosenfeld, a professor of environmental and occupational health sciences and pathology at the University of Washington.
Mice were exposed for a few hours, several days a week, to whole diesel exhaust at a particulate mass concentration within the range of what mine workers usually are exposed to.
After the exposures, UCLA scientists analyzed blood and tissue specimens and checked to see if the protective antioxidant and anti-inflammatory properties of HDL, known as "good" cholesterol, were still intact. They used special analytical laboratory procedures originally developed by study author Mohamad Navab at UCLA to evaluate how "good" or "bad" HDL had become. The team found that many of the positive properties of HDL were markedly altered after the air-pollutant exposure.
For example, the HDL of mice exposed to two weeks of vehicle emissions, including those that received a subsequent week of filtered air, had a much-decreased ability to protect against oxidation and inflammation induced by low-density lipoprotein (LDL) cholesterol, known as "bad" cholesterol, than the mice that had only been exposed to filtered air.
According to researchers, without HDL's ability to inhibit LDL, along with other factors, the oxidation process may run unchecked. Moreover, not only was the HDL of the mice exposed to diesel exhaust unable to protect against oxidation, but, in fact, it further enhanced the oxidative process and even worked in tandem with the LDL to promote even more oxidative damage.
Researchers also found a twofold to threefold increase of additional oxidation products in the blood of mice exposed to vehicle emissions, as well as activation of oxidation pathways in the liver. The degree of HDL dysfunction was correlated with the level of these oxidation markers.
"We suggest that people try to limit their exposure to air pollutants, as they may induce damage that starts during the exposure and continues long after it ends," said first author Fen Yin, a researcher in the division of cardiology at the Geffen School of Medicine.
The current research builds on the team's previous findings that ambient ultrafine particles commonly found in air pollution, including vehicle emissions, enhance the build-up of cholesterol plaques in the arteries and that HDL may play a role.
"Our research helps confirm that the functionality of HDL may be as important to check as the levels," said study author Dr. Alan Fogelman, executive chair of the department of medicine and director of the atherosclerosis research unit at the Geffen School of Medicine.
The study was funded by the National Institute of Environmental Health Sciences; the National Heart, Lung and Blood Institute; and the U.S. Environmental Protection Agency.
Additional authors included Akeem Lawal, Jerry Ricks, Julie R. Fox and Tim Larson.
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May 15, 2013 — Clam fossils from the middle Devonian era -- some 380 million years ago -- now yield a better paleontological picture of the capacity of ecosystems to remain stable in the face of environmental change, according to research published today (May 15) in the online journal PLOS ONE.
Trained to examine species abundance -- the head counts of specimens -- paleontologists test the stability of Earth's past ecosystems. The research shows that factors such as predation and organism body size from epochs-gone-by can now be considered in such detective work.
Back 380 million years ago, New York was under the Devonian sea. Today, the fossils found in the rocks of this region have become well known for documenting long-term stability in species composition -- that is, the same species have been found to persist with little change over a 5 million year period. But research has found that species abundance in this ancient ecosystem went up and down, generating debate among paleontologists whether the fauna, as a whole, was also stable in terms of its ecology.
A team of Cornell, Paleontological Research Institution (PRI) -- an affiliate of Cornell -- and University of Cincinnati researchers revisited this debate by examining the ecological stability of the Devonian clam fauna.
"To understand how these species fared in the Devonian, you have to look at how they interacted with other species. There is more to ecology than just the abundance and distribution of species," said Gregory Dietl, Cornell adjunct professor, earth and atmospheric sciences, and a paleontologist at PRI.
The research, "Abundance Is Not Enough: The Need for Multiple Lines of Evidence in Testing for Ecological Stability in the Fossil Record," was written by Judith Nagel-Myers, paleontologist, PRI; John Handley, PRI; Carlton Brett, University of Cincinnati professor of geology; and Dietl.
The scientists took a new approach to testing ecological stability: In addition to counting numbers of clams, they examined repair scars on fossil clams that were left by the unsuccessful attacks from shell-crushing predators, and the body size of the clam assemblage as it yields biological information on the structure of food webs.
"Surprisingly, predation pressure and the body size structure of the clams remained stable, even as abundance varied," said Nagel-Myers. Possible mechanisms that explain the clam assemblage's stability are related to the dynamics of food webs -- the same mechanisms operating in food webs today. In one mechanism, predators switched between feeding on different clam species as their abundance varied.
The ancient Devonian ecosystem was more complex than previously thought, as it cautions scientists against basing conclusions on a single factor. Said Dietl: "Our results thus raise serious doubt as to whether ecological stability can be tested meaningfully, solely based upon the abundance of taxa, which has been the standard metric used to test for ecological stability in paleoecology."
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African Clawed Frogs have long been suspected of introducing a harmful fungus called Batrachochytrium dendrobatidis or Bd to new populations that haven't been exposed to this pathogen before. The fungus has led to the recent decline or extinction of 200 frog species worldwide. A previous study found that the earliest case of Bd in the world was found in African Clawed Frogs in their native South Africa in 1934, but until now no research has tested for the disease among this species in populations that have become established in the U.S.
"We found that African Clawed Frogs that have been introduced in California are carrying this harmful fungus," said SF State biologist Vance Vredenburg. "This is the first evidence of the disease among introduced feral populations in the U.S., and it suggests these frogs may be responsible for introducing a devastating, non-native disease to amphibians in the United States."
From the 1930s to 1950s, thousands of African Clawed Frogs were exported across the world for use in pregnancy tests, scientific research and the pet trade. These frogs will ovulate when injected with a pregnant woman's urine.
"Today, these frog populations are often found in or near urban areas, probably because hospitals released them into the wild when new pregnancy testing methods were invented in the 1960s," Vredenburg said.
Named for the claws they use to catch prey, these greenish-grey frogs live in pools and streams and have established feral populations in the U.S., including in San Francisco's Golden Gate Park.
African Clawed Frogs are potentially potent carriers of the Bd fungus because they can be infected for long periods of time without dying, allowing them to pass it on to more vulnerable species.
"It's amazing that more than half a century after being brought to California, these frogs are still here, and they still carry this highly infectious disease," said Vredenburg, associate professor of biology at SF State. "This implies that there must be a stable relationship between the pathogen and the frogs, whereas there are other frog species, for example in the Sierra Nevada, which have been wiped out by the pathogen."
For this latest study, Vredenburg and colleagues tested museum specimens at the California Academy of Sciences. They assessed the prevalence of the disease by swabbing DNA from the skin of preserved African Clawed Frog specimens that were collected from wild populations in California between 2001 and 2010.
They also tested archived specimens collected in Africa between 1871 and 2010 and found evidence confirming that Bd was present among indigenous populations of this species before they were exported worldwide.
Although no longer used in pregnancy testing, African Clawed Frogs are still imported to the U.S. for use in biomedical and basic science research. Because of their suspected role as a carrier of the Bd fungus and other potential pathogens, eleven states in the U.S. have already restricted the importation of these frogs, for example by requiring special permits and not allowing them to be sold as pets.
"Back in the 1960s, African Clawed Frogs were kind of ignored in terms of conservation research but now the damage has been done," Vredenburg said. "Now, we need to be cautious about other introduced species, including those in the pet and food trade. There could be other animals out there that are carrying diseases that we don't even know about yet."
"Prevalence of Batrachochytrium dendrobatidis in Xenopus Collected in Africa (1871-2000) and in California (2001-2010)" was published May 15, 2013 in PLOS ONE. Vredenburg co-authored the paper with Samuel V. G. McNally, a graduate student in Vredenburg's lab, and Stephen A. Felt, Erica C. Morgan, Sabrina Wilson, and Sherril L. Green from Stanford University.
The research was supported by the National Science Foundation.
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Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
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Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
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