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2013年5月28日星期二

Understanding the past and predicting the future by looking across space and time

May 25, 2013 — Studying complex systems like ecosystems can get messy, especially when trying to predict how they interact with other big unknowns like climate change.

In a new paper published this week (May 20) in the Proceedings of the National Academy of Sciences, researchers from the University of Wisconsin-Madison and elsewhere validate a fundamental assumption at the very heart of a popular way to predict relationships between complex variables.

To model how climate changes may impact biodiversity, researchers like Jessica Blois and John W. (Jack) Williams routinely use an approach called "space-for-time substitution." The idea behind this method is to use the information in current geographic distributions of species to build a model that can predict climate-driven ecological changes in the past or future. But does it really work?

"It's a necessary assumption, but it's generally untested," says lead study author Blois, a former postdoctoral fellow with Williams at UW-Madison. She is now an assistant professor at the University of California, Merced. "Yet we're using this every day when we make predictions about biodiversity going into the future with climate change."

Their results should give other ecologists -- and potentially others such as economists who use similar models -- more confidence in their methods.

"At these spatial and temporal scales, the space-for-time assumption does work well," says Williams, professor of geography and director of the Center for Climatic Research at the UW-Madison Nelson Institute for Environmental Studies. "Our fossil data did support the idea that you can use spatial relationships as a source of information for making these predictions for the future."

Their research focus is paleoecology, the study of ancient ecosystems. By looking at fossilized pollen trapped in cores of sediment from the bottoms of lakes, the scientists reconstructed information about the plant communities present at locations across eastern North America during the past 21,000 years.

If climate has influenced communities the same way across space and through time, Blois explains, then a model based on the spatial data should make the same predictions as a model based on their temporal data. And in fact, they did.

The space-for-time model explained about 72 percent of the variation seen in their time data, and the remainder is likely due to other biological and environmental factors that the simplified model does not include, Blois says.

Though the testing does not capture all the ways space-for-time substitutions are used in other predictive fields, she says that the results are very encouraging for questions spanning large geographic and time scales -- scales at which collecting good temporal data can be very challenging.

"We found that at these broad time scales we're looking at, that space does substitute for time relatively well," Blois says. "It makes me more confident in my analyses going forward."

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Newly understood circuits add finesse to nerve signals

Researchers at the University of Alabama at Birmingham (UAB) discovered new details of a mechanism operating in the cerebellum, the brain region that processes nerve signals coming in from the spinal cord and cortex.

"Our results explain a second layer of nerve signal transmission that depends, not on whether a nerve cell is wired into a defined signaling pathway, but instead on how close it is to the pathway," said Jacques Wadiche, Ph.D., assistant professor in the Department of Neurobiology within the UAB School of Medicine, investigator in the Evelyn McKnight Brain Institute at UAB and senior study author. "It has become clear that this kind of nerve circuit is intimately linked with autism and movement disorders like ataxia, and we hope the mechanisms detailed here contribute to the design of new treatments."

Beyond nerve pathways Nerve cells are known to occur in defined pathways that transmit messages in one direction. This pathway-specific view of nerve signaling has been reinforced by high-tech imaging studies yielding detailed connectivity maps. Along these lines, the Obama Administration will soon ask Congress for $100 million in research funding to further improve such maps.

Within nerve pathways, each nerve cell sends an electric pulse down an extension of itself called an axon until it reaches a synapse, a gap between itself and the next cell in line. When it reaches an axon's end, the pulse triggers the release of chemicals called neurotransmitters that float across the gap, where they either cause the downstream nerve cell to "fire" and pass on the message, or stop the message. In this way, each synapse between nerve cells in a pathway "decides" whether or not a message continues on.

In recent years, studies have found that neurotransmitters also spill into tissue surrounding axons in a type signaling not restricted to synaptic connections. With the term itself implying a mess, "spillover" was thought to degrade the capacity of nerve cells to precisely pass on signals.

The current study adds to recent evidence arguing that spillover may instead enhance message transmission, with the results revolving around three nerve cell types in the cerebellum: climbing fibers, Purkinje cells and interneurons.

Climbing fibers, which carry information from the brainstem into the cerebellum, play key roles in motor timing and sensory processing. Within these fibers, nerve cells release the excitatory neurotransmitter glutamate into synapses that then strive to pass messages deeper into the cerebellum. Purkinje cells are paired with climbing fibers and intent on inhibiting their signals.

When excited by glutamate from climbing fibers at one end, Purkinje cells release another neurotransmitter called GABA at their downstream synapse to stop the message. An excitatory signal triggers an inhibitory one as a counter-balance, a form of feedback critical to the function of the central nervous system. Lack of inhibition, for instance, causes circuits to seize, seizures and the death of Purkinje cells, the latter of which has been linked by post mortem studies to a higher incidence of autism spectrum disorders.

Previously, researchers thought that incoming signals from climbing fibers caused a single, strong response in the cerebellum: the activation of Purkinje cells that released GABA. The current study argues that such signals also trigger the firing of interneurons, nearby inhibitory middlemen that connect sets of nerve cells.

Interneurons within, and outside of, the glutamate spill zone around climbing fibers may have different effects on the other interneurons and Purkinje cells they connect to, according to the current finding. The interactions either inhibit or excite many Purkinje cells surrounding an active climbing fiber and refine its messages in a feedback system more sophisticated than once thought.

Glutamate has its effect by fitting into AMPA and NMDA receptor proteins, like a key into a lock, on the surfaces of nerve cells it signals to. The consensus has been that glutamate receptors occur only within synapses. Finding them on nerve cells outside of synapse-defined pathways represents "a fundamental shift in understanding," said Wadiche, and may result in longer-lasting inhibition within key signaling pathways.

"A 2007 study published in Nature Neuroscience found that many climbing fibers signal to interneurons in the outer layer of the cerebellum outside nerve pathways and exclusively through glutamate spillover," said Luke Coddington, a graduate student in Wadiche's lab and study author. "Our team built on that observation to show how spillover affects the function of interneurons, Purkinje cells, and ultimately, the entire cerebellum. Spillover-mediated signaling recruits local microcircuits to extend the reach and finesse of climbing fiber signaling."

Linda Overstreet-Wadiche, Ph.D., was also senior co-author of the study, with important contributions also coming from Stephanie Rudolph and Patrick Vande Lune, all within the Department of Neurobiology.

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Research gap threatens innovation, experts warn

MOUNTAIN VIEW, Calif. – The innovation pipeline could run dry from a lack of federal funding in basic research and the decline of big corporate R&D labs, said a panel of experts at an event celebrating the 40th anniversary of Ethernet.

They lamented the loss of AT&T Bell Labs that gave birth to the transistor and the decline of Xerox PARC, the birthplace of Ethernet. By contrast many of today’s largest tech companies, such as Apple—accused by Congress this week for failing to pay taxes on billions in revenue—conduct virtually no basic research, they said.

“When I was at Xerox people were not preoccupied with raising millions in VC funds-- we had free reign to make breakthroughs come true,” said Yogen Dalal, a managing director at the Mayfield Fund who wrote a seminal paper on Ethernet in its early days. “You have to have breakthroughs, but today who will fund them,” he asked.

“The thing that concerns me the most is we have lost the lead in big industrial research—we would never have had the transistor without Bell Labs,” said Bill Spencer, former head of PARC and Sematech. “The U.S. still has the best university system in world, and it’s still the best place to bring new things to market, but the middle missing,” he said.

Bill Spencer led PARC in the early days of Ethernet.

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Students perform well regardless of reading print or digital books

Jim Johnson, who also is director of instructional and information technology services in the Bayh College of Education, surveyed more than 200 students. Half of the students used an iPad2 to read a textbook chapter while the other half of the students read from a printed textbook chapter. The students then took an open-book quiz with eight easy and eight moderate questions on the chapter.

"Few people have done a lot of research into what I'm doing," Johnson said. "Mine directly ties performance with perception by undergraduates."

Johnson's research specifically examined three questions: Are there any significant differences in reading comprehension test scores of students when using paper texts versus digital texts? Are there any differences in reading comprehension test scores with regard to gender or between text formats and gender? Is there a relationship between the hours of experience using tablet computers and reading comprehension test scores among study participants?

"No matter what the format, no matter what the preference, they did well," he said. "It was interesting that the gender didn't matter on the test scores."

Men had a mean score of 12.87 out of 16 while women had an average score of 13.60 out of 16. Students age 21 had an average score of 13.87 out of 16 while students 25 and older had an average score of 13.5 out of 16.

He also found that there was no significant difference on test scores whether or not the participant had past experience on a tablet.

"The delivery method didn't make any difference," he said.

Of the participants, 88 percent said they had read books on laptops, netbooks or desktops while 51 percent said they had used an iPad, iPhone or iPod to read books. Additionally 36.1 percent said they used a cell phone to look at digital texts. When asked what they would like to use, 69.1 percent said they would want to use an iPad, iPhone or iPod to read digital text and almost the same amount, 68.7 percent, said they would prefer a laptop, netbook or desktop computer. Only 48.1 percent said they would want to use an e-book reader. In considering digital textbook readers, 74.7 percent said the ability to browse the Internet was important while 70.4 said they wanted to read email, 62.7 percent said cheapest price was important. Of the prices students said they would pay, 40 percent said between $100 and $200 while 16.7 percent said they would pay between $200 and $249.

"The bulk of undergraduate students are looking at cheaper devices. That's important for students," he said. "The market is driving our students to Android devices like Kindle."

However, some problems remain in the digital textbook market. Students expressed concern about eye strain from reading text on electronic devices. Johnson said one participant became so nauseous reading the digital text that she was unable to complete the study. Also students expressed concern about the high price of digital textbooks as well as the battery life, software and reliable technology.

In focus groups after the initial test, Johnson said students didn't like the high cost of digital book rental or the inability to resell digital textbooks.

"A lot of the students didn't like the idea of renting books," he said.

Johnson said there needs to be further discussion about the cost of digital textbooks and how to keep costs down. Faculty members also need to be encouraged to write and create their own digital textbooks and resources for students, he said.

Digital texts would allow professors to use the most current resources.

"Publishing on paper is always slower," he said. "Delivery options for students are important. Information should be on demand."

In the future, Johnson said professors could select chapters from different digital textbooks and combine it into one digital textbook so students wouldn't have to buy different textbooks to read chapters that the professors like.

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New analysis yields improvements in a classic 3-D imaging technique

May 25, 2013 — Research conducted at Curtin University in Perth has enabled significant increases in image quality in a widely used 3D printing technique that is more than 100 years old.

Anaglyph printing -- think of the red-and-blue 3D glasses used to transform 2D images to 3D images in comics, magazines, books, and newspapers -- came into being when the continuous-tone printed anaglyph was invented by French physicist Louis Ducos du Hauron in 1891.

The technique works by combining the left and right images of a stereoscopic image pair into the red and blue color channels of the output anaglyph image. With the red/blue 3D glasses, the left eye sees only the red channel of the anaglyph image, and the right sees only the blue. If the anaglyph 3D image has been constructed correctly, the viewer sees a pleasing 3D image on the printed page.

The project team, led by Curtin research engineer Andrew Woods, targeted crosstalk problems which are visible as ghost-like shadows. Their paper published recently in the SPIE journal Optical Engineering details seven recommendations for overcoming crosstalk.

"The largest reduction in crosstalk is likely be achieved by using inks which have a better spectral purity than current process inks used in color printers," Woods said. "We found that an 80% reduction in crosstalk was potentially achievable just by changing the cyan ink."

The anaglyph technique is easy to implement and the anaglyph 3D glasses are relatively cheap, so the technique is used very widely, Woods said.

However, printed anaglyph images often suffer from a number of image quality limitations. When the 3D image is viewed through the colored glasses, there is often a significant amount of crosstalk (or ghosting), an undesirable property of some 3D techniques whereby the left eye sees some of the image intended for only the right eye, and vice-versa. Crosstalk is usually visible as ghost-like shadows throughout the image. If crosstalk levels are too high, the quality of the 3D experience can be significantly reduced.

"The printed anaglyph is 121 years old, but this appears to be the first time that a detailed technical simulation of crosstalk in printed anaglyphs has been developed," Woods said. "We started by measuring the spectral characteristics of various printing inks, 3D glasses, light sources, and papers. From there we developed a simulation which models the viewing of an anaglyph 3D image, and subsequently performed an experiment to validate the accuracy of the model. We hope this work will help provide a 21st-century improvement to the 19th-century invention."

In addition to changing the cyan ink, recommendations include using high-quality anaglyph glasses, an optimized light source, and improved image processing algorithms.

The full paper is available via open access in the SPIE Digital Library: "Characterizing and reducing crosstalk in printed anaglyph stereoscopic 3D images."

The work was originally presented in the Stereoscopic Displays and Applications conference during the 2013 IS&T/SPIE Electronic Imaging symposium in Burlingame, California, USA. The call for papers has been released for Electronic Imaging 2014 which will be held 2-6 February in downtown San Francisco.

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Cloud-based virtualization goes mobile

LOS ANGELES--Virtualization and cloud orchestration turned a corner here at Citrix Synergy 2013 this week, where for the first time users' Windows desktops became available on any PC, Mac, Android or iOS device, taking virtualization to its logical conclusion of allowing business users to access their desktops from any laptop, tablet or smartphone.

Cloud service providers also got a boost this week as Citrix demonstrated its IT innovation called IT-as-a-service, which allows any SP to muscle into the cloud service space that today is dominated by Amazon, Microsoft, Oracle, Rackspace and a few other giants. Also at the event, Nvidia Corp. demonstrated how its virtual graphics processing unit (vGPU) capabilities can be used to run intensive cloud-based applications at speeds indistinguishable from those on a local GPU.

"The partner model is the core of our virtualization and cloud orchestration businesses," said Mark Templeton, president and CEO of Citrix Systems, Inc. (Ft. Lauderdale, Fla.). "In the end, each IT organization has to be responsible for their users' experience—Citrix just serves as a proxy for them by making sure that a user's apps are always up to date. However, the content—all the data—belongs to our customers, and we make sure it is our customer's brand--not Citrix--that is prominently displayed to their users."

Mark Templeton, president and CEO of Citrix, speaks at the Citrix Synergy event.

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2013年5月23日星期四

Depression linked to telomere enzyme, aging, chronic disease

Now a research team led by Owen Wolkowitz, MD, professor of psychiatry at UC San Francisco, has found that within cells of the immune system, activity of an enzyme called telomerase is greater, on average, in untreated individuals with major depression. The preliminary findings from his latest, ongoing study will be reported today at the annual meeting of the American Psychiatric Association in San Francisco.

Telomerase is an enzyme that lengthens protective end caps on the chromosomes' DNA, called telomeres. Shortened telomeres have been associated with earlier death and with chronic diseases in population studies.

The heightened telomerase activity in untreated major depression might represent the body's attempt to fight back against the progression of disease, in order to prevent biological damage in long-depressed individuals, Wolkowitz said.

The researchers made another discovery that may suggest a protective role for telomerase. Using magnetic resonance imaging (MRI), they found that, in untreated, depressed study participants, the size of the hippocampus, a brain structure that is critical for learning and memory, was associated with the amount of telomerase activity measured in the white blood cells. Such an association at a single point in time cannot be used to conclude that there is a cause-and-effect relationship with telomerase helping to protect the hippocampus, but it is plausible, Wolkowitz said.

Remarkably, the researchers also found that the enzyme's activity went up when some patients began taking an antidepressant. In fact, depressed participants with lower telomerase activity at baseline -- as well as those in whom enzyme activity increased the most with treatment -- were the most likely to become less depressed with treatment.

"Our results are consistent with the beneficial effect of telomerase when it is boosted in animal studies, where it has been associated with the growth of new nerve cells in the hippocampus and with antidepressant-like effects, evidenced by increased exploratory behavior," Wolkowitz said. Wolkowitz cautions that his new findings are preliminary due to the small size of the study and must be confirmed through further research.

The researchers also measured telomere length in the same immune cells. Only very chronically depressed individuals showed telomere shortening, Wolkowitz said.

"The longer people had been depressed, the shorter their telomeres were," he said. "Shortened telomere length has been previously demonstrated in major depression in most, but not all, studies that have examined it. The duration of depression may be a critical factor."

The 20 depressed participants enrolled in the study had been untreated for at least six weeks and had an average lifetime duration of depression of about 13 years. After baseline evaluation and laboratory measures, 16 of the depressed participants were treated with sertraline, a member of the most popular class of anti-depressants, the serotonin-selective-reuptake-inhibitors (SSRIs), and then evaluated again after eight weeks. There were 20 healthy participants who served as controls.

The ongoing study still is accepting depressed participants who are not now taking antidepressants. Wolkowitz's team also studies chronic inflammation and the biochemical phenomenon of oxidative stress, which he said have often been reported in major depression. Wolkowitz is exploring the hypothesis that inflammation and oxidative stress play a role in telomere shortening and accelerated aging in depression.

"New insights into the mechanisms of these processes may well lead to new treatments -- both pharmacological and behavioral -- that will be distinctly different from the current generation of drugs prescribed to treat depression," he said. "Additional studies might lead to simple blood tests that can measure accelerated immune-cell aging."

Wolkowitz's research is funded by the National Institutes of Health. He is on the scientific advisory board of Telome Health, Inc., a private biotechnology company.

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Vast methane-based ecosystem uncovered

The seep lies deep in the western North Atlantic Ocean, far from the life-sustaining energy of the sun. Mussels blanketing the the seep rely on bacteria that use the methane to make energy. The process, known as chemosynthesis, forms the basis for life in the harsh environment and could help scientists better understand how organisms can survive under these types of extreme conditions.

"UNCW and FSU have done two previous cruises together and this is perhaps our biggest discovery," said UNCW researcher Dr. Steve Ross. "Studies of this kind and of these communities help scientists understand how life thrives in harsh environments, and perhaps even on other planets."

The new seep discovery is only the third documented seep site on the U.S. Atlantic Coast, and by far the most extensive; the two seep areas at this site are estimated to be at least a kilometer long and in places hundreds of meters across. Sea cucumbers were also seen tucked into the tight mounds of mussels and shrimp swam above them. Many species of fishes, including some with unusual behaviors, were also common around the unique ecosystem..

Stationed aboard NOAA's Ronald H. Brown research vessel, the research teams used the diverse capabilities of the Woods Hole Oceanographic Institution's Remotely Operated Vehicle (ROV), Jason II, to document and study the newly discovered methane seep.. The teams have been able to capture high definition video, sample the sediment at the site, collect live mussels for genetic and reproductive studies, collect large dead shells and rocks for aging analysis, take water samples to examine water chemistry, and sample associated animals to examine food webs.

The seep discovery could potentially play an important role in advancing scientific understanding of hydrocarbon resources and gas hydrates (important possible future energy resources) along the US continental slope .

Major funding for the research expedition was provided by the Bureau of Ocean Energy Management, with NOAA providing funding for the Ronald H. Brown and Jason ROV. US Geological Survey and other collaborators also provided a variety of resources.

TAG:Extreme Survival Fish Marine Biology Sustainability Energy and the Environment Renewable Energy

First genomic survey of human skin fungal diversity

Human skin surfaces are complex ecosystems for microorganisms, including fungi, bacteria and viruses, which are known collectively as the skin microbiome. Although fungal infections of the skin affect about 29 million people in the United States, fungi can be slow and hard to grow in laboratories, complicating diagnosis and treatment of even the most common fungal skin conditions, such as toenail infections.

The research team from the National Human Genome Research Institute (NHGRI) and the National Cancer Institute (NCI), both parts of NIH, extended their recent genome sequencing study of skin bacteria, using DNA sequencing techniques optimized for identifying fungi. The study appears in the May 22, 2013 early online issue of Nature.

The researchers found that a single type of fungus, belonging to the genus Malassezia, is predominant on the head and trunk. Hands, which harbor a great diversity of bacteria, are home for relatively few types of fungi. In contrast, feet, including toenails, heels and toe webs contain tremendous diversity.

"Applying DNA sequencing to a study of the skin's fungi is the natural progression in understanding microbial life that co-exists on our bodies," said NHGRI Scientific Director Daniel Kastner, M.D., Ph.D. "Along with recent genome sequencing to define bacterial diversity, this analysis of fungal diversity provides a more complete human microbiome picture."

"Fungal communities occupy complex niches, even on the human body," said Heidi Kong, M.D., co-senior author and an investigator in the dermatology branch of NCI's Center for Cancer Research. "By gaining a more complete awareness of the fungal and bacterial ecosystems, we can better address associated skin diseases, including skin conditions which can be related to cancer treatments."

The researchers collected samples at 14 body sites from 10 healthy adults. DNA sequencing of the fungi in the samples identified fragments of DNA, called phylogenetic markers, which can be counted and used to distinguish one type of fungus from another. The sequencing efforts generated more than 5 million markers, from the samples, representing more than 80 fungal types, or genera. In contrast, traditional culturing methods produced 130 colonies of fungi that represented only 18 fungal genera.

In 20 percent of the study participants, the researchers observed problems such as heel and toe web scaling or toenail changes consistent with possible fungal infections. From genome sequencing analysis, the researchers found that different individuals with heel site infections have common fungal communities at that site, while those with toenail infections display tremendously different fungal communities.

"DNA sequencing reveals the great diversity of fungi, even those that are hard to grow in culture," said Julie Segre, Ph.D., co-senior author and senior investigator, NHGRI Genetics and Molecular Biology Branch. Her expertise is the development of microbial DNA sequencing technology. "DNA sequencing enabled us to learn immeasurably more about where fungi predominate as a part of the human skin microbiome."

The researchers identified fungi from two phyla, Ascomycetes and Basidiomycetes, as part of the normal fungal census at the 14 skin sites. The most common genus Malassezia was present in 11 of 14 sites sampled on the body. The researchers found Malassezia fungus on every skin surface of healthy volunteers, whether on the back of the head, behind the ears, in nostrils and on the heels. Heels were also home to many additional fungi, including the genera Aspergillus, Cryptococcus, Rhodotorula, and Epicoccum.

"DNA sequence-based methods of identification enabled us to differentiate among species of fungi and to conclude that the diversity of fungi is highly dependent on the body site rather than the person who is sampled," said Dr. Kong. A dermatologist, Dr. Kong explained why these sites were selected for exploration: "Our study focused on areas of the skin where we commonly find skin diseases that have been associated with fungi."

The most complex site, the heel, is home to about 80 genus-level types of fungi. The researchers found about 60 types in toenail swab samples and 40 types in samples from the webs of the toes. Sites with moderate fungal diversity are inside the bend of the arm, inside of the forearm and palm, with each location supporting 18 to 32 genera of fungi. Surprisingly, head and trunk body sites -- including the back, back of the neck, inside the ears, behind the ears, and between the eyebrows -- have far fewer fungi types, with just two to 10 genera each.

The research team compared fungal diversity data with the skin bacteria on the same healthy adults. They found that while arms have high measures of bacterial diversity, they have lower fungal diversity. They found the reverse to be true for sites on the feet. Core body sites had neither a high bacterial diversity nor a high fungal diversity. The researchers had previously shown that bacterial diversity can be predicted by whether skin is moist, dry or oily. Fungal diversity, instead, seems to depend upon where a particular skin site is on the body.

The researchers observed, in addition, that there is greater similarity in the fungal community structure on the left and right sides of the same person's body compared to the same body parts on any two individuals. Fungal communities also appear to be quite stable over time, with little change when tested on two separate occasions, up to three months apart.

"The data from our study gives us a baseline about normal individuals that we never had before," Dr. Segre said. "The bottom line is your feet are teeming with fungal diversity, so wear your flip flops in locker rooms if you don't want to mix your foot fungi with someone else's fungi."

TAG:Skin Care Human Biology Psoriasis Fungus Microbes and More Microbiology

Largest genetic sequencing study of human disease

May 22, 2013 — Researchers from Queen Mary, University of London have led the largest sequencing study of human disease to date, investigating the genetic basis of six autoimmune diseases.

The exact cause of these diseases -- autoimmune thyroid disease, celiac disease, Crohn's disease, psoriasis, multiple sclerosis and type 1 diabetes- is unknown, but is believed to be a complex combination of genetic and environmental factors. In each disease only a proportion of the heritability is explained by the identified genetic variants. The techniques used to date, have generally identified common (in the population) variants of weak effect.

In this study, using high-throughput sequencing techniques,a global team of scientists sought to identify new variants, including rare and potentially high risk ones, in 25 previously identified risk genes in a sample of nearly 42,000 individuals (24,892 with autoimmune disease and 17,019 controls).

It has been suggested -- in the 'rare-variant synthetic genome-wide association hypothesis' -- that a small number of rare variants in risk genes are likely to be a major cause of the heritability of these conditions. However, the study published today in the journal Nature, suggests that the genetic risk of these diseases more likely involves a complex combination of hundreds of weak-effect variants which are each common in the population.

The authors estimate that rare variants in these risk genes account for only around three per cent of the heritability of these conditions that can be explained by common variants.

David van Heel, Professor of Gastrointestinal Genetics at Barts and The London School of Medicine and Dentistry at Queen Mary and director of the Barts and The London Genome Centre, led the study. He said: "These results suggests that risk for these autoimmune diseases is not due to a few high-risk genetic variations but seems rather due to a random selection from many common genetic variants which each have a weak effect.

"For each disease there are probably hundreds such variants and the genetic risk is likely to come from inheriting a large number of these variants from both parents. If this is the case then it may never be possible to accurately predict an individual's genetic risk of these common autoimmune diseases. However, the results do provide important information about the biological basis of these conditions and the pathways involved, which could lead to the identification new drug targets."

The research utilised high-throughput sequencing techniques performed at the Barts and The London Genome Centre and demonstrated for the first time that the sequencing can call genotypes as accurately as 'gold standard techniques' such as genotyping array platforms. Additional laboratory work was carried out at the Blizard institute at Queen Mary.

Professor Richard Trembath, Vice Principal and Executive Dean for Health at Barts and The London School of Medicine and Dentistry, Queen Mary, and a co-author on the paper said: "The results prompt a re-assessment of the genetic architecture that determines risk for development of common auto-immune disorders and will fuel future careful assessment of regions of the human genome beyond those presently known to confer susceptibility to these important medical conditions."

This study was primarily funded by the Medical Research Council with additional funding from Coeliac UK.

TAG:Personalized Medicine Diseases and Conditions Asthma Genes Cholesterol Chronic Illness

Model of Sun's magnetic field created

Scientists have known since the 18th Century that the Sun regularly oscillates between periods of high and low solar activity in an 11-year cycle, but have been unable to fully explain how this cycle is generated.

In the 'Information Age', it has become increasingly important to be able to understand the Sun's magnetic activity, as it is the changes in its magnetic field that are responsible for 'space weather' phenomena, including solar flares and coronal mass ejections. When this weather heads in the direction of Earth it can damage satellites, endanger astronauts on the International Space Station and cause power grid outages on the ground.

The research, published in the journal Nature, explains how the cyclical nature of these large-scale magnetic fields emerges, providing a solution to the mathematical equations governing fluids and electromagnetism for a large astrophysical body.

The mechanism, known as a dynamo, builds on a solution to a reduced set of equations first proposed in the 1950s which could explain the regular oscillation but which appeared to break down when applied to objects with high electrical conductivity. The mechanism takes into account the 'shear' effect of mass movement of the ionised gas, known as plasma, which makes up the Sun. More importantly it does so in the extreme parameter regime that is relevant to astrophysical bodies.

"Previously, dynamos for large, highly conducting bodies such as the Sun would be overwhelmed by small-scale fluctuations in the magnetic field. Here, we have demonstrated a new mechanism involving a shear flow, which served to damp these small-scale variations, revealing the dominant large-scale pattern," said Professor Steve Tobias, from the University of Leeds' School of Mathematics, a co-author of the research.

What is more, this mechanism could be used to describe other large, spinning astronomical bodies with large-scale magnetic fields such as galaxies.

The dynamo was developed through simulations using the high-performance computing facilities located at the University of Leeds.

"The fact that it took 50 years and huge supercomputers shows how complicated the dynamo process really is." said Prof Fausto Cattaneo, from the University of Chicago's Department of Astronomy and Astrophysics.

The presence of spots on the Sun has been known since antiquity, and further analysed after the invention of the telescope by Galileo in the 16th Century. However, their cyclic nature, with periods of high activity (lots of sunspots) and low activity (few sunspots) following each other, was not identified until the 18th Century. At the start of the 20th Century it was then recognised that these sunspots were the result of the Sun's magnetic field. Since then much effort has been devoted to understanding what processes lead to the formation of sunspots and the origin of their cyclic behaviour.

TAG:Sun Solar Flare Astronomy Space Telescopes Space Exploration Northern Lights

Fragile mega-galaxy is missing link in history of cosmos

May 22, 2013 — Two hungry young galaxies that collided 11 billion years ago are rapidly forming a massive galaxy about 10 times the size of the Milky Way, according to UC Irvine-led research published Wednesday in the journal Nature.

Capturing the creation of this type of large, short-lived star body is extremely rare -- the equivalent of discovering a missing link between winged dinosaurs and early birds, said the scientists, who relied on the once-powerful Herschel space telescope and observatories around the world. The new mega-galaxy, dubbed HXMM01, "is the brightest, most luminous and most gas-rich submillimeter-bright galaxy merger known," the authors write.

HXMM01 is fading away as fast as it forms, a victim of its own cataclysmic birth. As the two parent galaxies smashed together, they gobbled up huge amounts of hydrogen, emptying that corner of the universe of the star-making gas.

"These galaxies entered a feeding frenzy that would quickly exhaust the food supply in the following hundreds of million years and lead to the new galaxy's slow starvation for the rest of its life," said lead author Hai Fu, a UC Irvine postdoctoral scholar.

The discovery solves a riddle in understanding how giant elliptical galaxies developed quickly in the early universe and why they stopped producing stars soon after. Other astronomers have theorized that giant black holes in the heart of the galaxies blew strong winds that expelled the gas. But cosmologist Asantha Cooray, the UC Irvine team's leader, said that they and colleagues across the globe found definitive proof that cosmic mergers and the resulting highly efficient consumption of gas for stars are causing the quick burnout.

"Finding this type of galaxy is as important as the discovery of the archaeopteryx was in understanding dinosaurs' evolution into birds, because they were both caught at a critical transitional phase," Fu said.

The new galaxy was initially spotted by UC Irvine postdoctoral scholar Julie Wardlow, also with Cooray's group. She noticed "an amazing, bright blob" in images of the so-called cold cosmos -- areas where gas and dust come together to form stars -- recorded by the European Space Agency's Herschel telescope with important contributions from NASA's Jet Propulsion Laboratory in Pasadena. "Herschel captured carpets of galaxies, and this one really stood out."

Follow-up views at a variety of wavelengths were obtained at more than a dozen ground-based observatories, particularly the W. M. Keck Observatory in Hawaii.

TAG:Galaxies Astrophysics Stars Cosmology Astronomy Space Telescopes

Promising new approach to treatment of lung cancer

This advance in nanomedicine combines the extraordinarily small size of nanoparticles, existing cancer drugs, and small interfering RNA (siRNA) that shut down the ability of cancer cells to resist attack.

The combination of these forces resulted in the virtual disappearance of lung tumors in experimental animals.

Lung cancer is the leading cancer killer in both men and women. Despite advances in surgery, chemotherapy still plays a major role in its treatment. However, that treatment is constrained by the toxic effects of some drugs needed to combat it and the difficulty of actually getting those drugs into the lungs.

The findings were made by Oleh Taratula at Oregon State University and Tamara Minko and O. Garbuzenko at Rutgers University and the Cancer Institute of New Jersey. They were just published in the Journal of Controlled Release.

"Lung cancer damage is usually not localized, which makes chemotherapy an important part of treatment," said Taratula, an assistant professor in the OSU College of Pharmacy and co-author on this study. "However, the drugs used are toxic and can cause organ damage and severe side effects if given conventionally through intravenous administration.

"A drug delivery system that can be inhaled is a much more efficient approach, targeting just the cancer cells as much as possible," he said. "Other chemotherapeutic approaches only tend to suppress tumors, but this system appears to eliminate it."

A patent is being applied for on the technology, and more testing will be necessary before it is ready for human clinical trials, the researchers said.

The foundation of the new system is a "nanostructured lipid nanocarrier," tiny particles much smaller than a speck of dust that are easily inhaled and also readily attach to cancer cells. This carrier system delivers the anticancer drug. However, it also brings siRNA that makes the cancer cell more vulnerable.

Cancer cells often have two forms of resistance to drugs -- "pump" resistance that tends to pump the drug out of cells, and "nonpump" resistance that helps keep the cell from dying. The siRNA used in this system helps to eliminate both those forms of resistance, and leaves the cancer cell vulnerable to the drug being used to kill it.

By being inhaled, this system also avoids degradation of the chemotherapeutic agents that occurs when they are injected, researchers said. They arrive in more intact form, ready to do their job on lung cancer cells, while minimizing any side effects.

In more conventional chemotherapy for lung cancer, the drugs tend to accumulate in the liver, kidney and spleen, with much less of the drugs ever making it to the lungs. In this study, the amount of the drug delivered to the lungs rose to 83 percent with the inhalation approach, versus 23 percent with injection.

This work was supported by the National Cancer Institute, National Science Foundation, and the Department of Defense.

TAG:Lung Cancer Colon Cancer Cancer Prostate Cancer Lung Disease Diseases and Conditions

Forecast for Saturn's moon Titan: Wild weather could be ahead

May 22, 2013 — Saturn's moon Titan might be in for some wild weather as it heads into its spring and summer, if two new models are correct. Scientists think that as the seasons change in Titan's northern hemisphere, waves could ripple across the moon's hydrocarbon seas, and hurricanes could begin to swirl over these areas, too. The model predicting waves tries to explain data from the moon obtained so far by NASA's Cassini spacecraft. Both models help mission team members plan when and where to look for unusual atmospheric disturbances as Titan summer approaches.

"If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan," said Scott Edgington, Cassini's deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We know there are weather processes similar to Earth's at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can't wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer."

Titan's north polar region, which is bejeweled with sprawling hydrocarbon seas and lakes, was dark when Cassini first arrived at the Saturn system in 2004. But sunlight has been creeping up Titan's northern hemisphere since August 2009, when the sun's light crossed the equatorial plane at equinox. Titan's seasons take about seven Earth years to change. By 2017, the end of Cassini's mission, Titan will be approaching northern solstice, the height of summer.

Given the wind-sculpted dunes Cassini has seen on Titan, scientists were baffled about why they hadn't yet seen wind-driven waves on the lakes and seas. A team led by Alex Hayes, a member of Cassini's radar team who is based at Cornell University, Ithaca, N.Y., set out to look for how much wind would be required to generate waves. Their new model, just published in the journal Icarus, improves upon previous ones by simultaneously accounting for Titan's gravity; the viscosity and surface tension of the hydrocarbon liquid in the lakes; and the air-to-liquid density ratio.

"We now know that the wind speeds predicted during the times Cassini has observed Titan have been below the threshold necessary to generate waves," Hayes said. "What is exciting, however, is that the wind speeds predicted during northern spring and summer approach those necessary to generate wind waves in liquid ethane and/or methane. It may soon be possible to catch a wave in one of the solar system's most exotic locations."

The new model found that winds of 1 to 2 mph (2 to 3 kilometers per hour) are needed to generate waves on Titan lakes, a speed that has not yet been reached during Titan's currently calm period. But as Titan's northern hemisphere approaches spring and summer, other models predict the winds may increase to 2 mph (3 kilometers per hour) or faster. Depending on the composition of the lakes, winds of that speed could be enough to produce waves 0.5 foot (0.15 meter) high.

The other model about hurricanes, recently published in Icarus, predicts that the warming of the northern hemisphere could also bring hurricanes, also known as tropical cyclones. Tropical cyclones on Earth gain their energy from the build-up of heat from seawater evaporation and miniature versions have been seen over big lakes such as Lake Huron. The new modeling work, led by Tetsuya Tokano of the University of Cologne, Germany, shows that the same processes could be at work on Titan as well, except that it is methane rather than water that evaporates from the seas. The most likely season for these hurricanes would be Titan's northern summer solstice, when the sea surface gets warmer and the flow of the air near the surface becomes more turbulent. The humid air would swirl in a counterclockwise direction over the surface of one of the northern seas and increase the surface wind over the seas to possibly 45 mph (about 70 kilometers per hour).

"For these hurricanes to develop at Titan, there needs to be the right mix of hydrocarbons in these seas, and we still don't know their exact composition," Tokano said. "If we see hurricanes, that would be one good indicator that there is enough methane in these lakes to support this kind of activity. So far, scientists haven't yet been able to detect methane directly."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. The mission is managed by JPL for NASA's Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology in Pasadena, Calif.

For more information about Cassini and its mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

TAG:Saturn Solar System Astronomy Space Exploration NASA Space Missions

2013年2月27日星期三

男性养生:四种壮阳法让你男人味十足!【5】

　　壮阳方法漫天飞舞，如按摩，如食补，你会选择什么样的方法呢？壮阳固然重要，但是可不要掉进壮阳误区哦，教你几种壮阳方法，让你更有男人味！

　　一、冷热水交替浴可提高中老年男子的性机能

　　这是一种很古老的增强男子性功能的锻炼方法。使用冷热水交替浴时，最好在澡盆内充分温热之后再出澡盆，给阴部施加冷水，待3分钟左右，阴茎、阴囊收缩之后再入浴盆。如此反复3-5次后即可结束，若能每日坚持做"交替浴"，可使中年以后的男性精力充沛、性功能增强、减轻疲劳感、该冷热水"交替浴"，使用淋浴用的莲蓬头，其效果不变。

　　二、适用于年轻男子的“空冷式”锻炼法

　　对睾丸来说，盖着被子睡觉不能说是良好的睡眠状态。如前所述，睾丸生产精子和雄性激素的最佳温度是比体温稍低的温度，所以，阴囊不能良好地散热会影响睾丸功能。

　　睾丸在应该进行重要活动时，却陷入棉被的闷热之中，这对睾丸来说是非常不利的，其实，解决的办法很简单。这就是将阴囊暴露在较凉爽的空气中睡眠，使阴囊能良好的通风散热。对于年轻人来说，这种"空冷式"锻炼法远比"冷热水交替式"锻炼法方便且更具成效。

　　如果可能，一年四季都将阴囊暴露在空气中睡眠当然是好的。但若是在冬季，恐怕要招致感冒。此时最好盖着被子不穿三角裤睡眠。若室内装有空调机保持恒温，就用不着把被子捂得太严。

　　"空冷式"锻炼法对激素的分泌影响极大，且效果极佳。临床性功能障碍患者中，采用该方法数月之后，精力明显恢复，性生活得以改善。

　　三、按摩阴囊具有强化男性精力之效

　　为提高男性性功能，养成用手直接按摩阴囊的习惯是其方法之一，时常按摩，睾丸便会改善循环。由于可经常不断地供给睾丸以新鲜血液，当然会增强睾丸功能，提高男性精力。

　　按摩可一日一次，每次2-3分钟即可。用手指从阴囊上部轻轻揉搓睾丸。如果时间过长，刺激过强，反而会使睾丸功能低下。请注意，"过犹不及"只能适得其反。

　　按摩最好是一日一次，养成每日一次的习惯远比偶尔为之更具成效。

　　四、刺激腹股沟管部可强化睾丸功能

　　如前所述，按摩睾丸可增强男性性功能。但更具效果的是刺激位于阴茎根部两侧的腹股沟管。腹股沟是向睾丸输送血液和连接神经的通路。如果腹股沟管机能低下，必然会引起睾丸功能低下。因此，重要的是使腹股沟管中的血液循环良好。

　　按摩腹股沟管的方法是分别用两个手指按压阴茎根部两侧，从上向下抚摩，刺激血液流向睾丸的通路。每日按摩一次，可在每晚入睡前自己在床上按摩。另外，在洗澡时可利用淋浴的莲蓬头用温水刺激该部，也能改善血液循环，强化睾丸功能。

TAG:壮阳按摩阴囊腹股沟管睾丸功能空冷式养生男性性功能冷热水血液循环

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