星空女人频道: 2013-05-19

2013年5月25日星期六

Students perform well regardless of reading print or digital books

May 24, 2013 — Research by an Indiana State University doctoral student found that students did equally well on a test whether reading from a digital book or a printed one.

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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Advanced biological computer developed

May 23, 2013 — Using only biomolecules (such as DNA and enzymes), scientists at the Technion-Israel Institute of Technology have developed and constructed an advanced biological transducer, a computing machine capable of manipulating genetic codes, and using the output as new input for subsequent computations. The breakthrough might someday create new possibilities in biotechnology, including individual gene therapy and cloning.

The findings appear today (May 23, 2013) in Chemistry & Biology (Cell Press).

Interest in such biomolecular computing devices is strong, mainly because of their ability (unlike electronic computers) to interact directly with biological systems and even living organisms. No interface is required since all components of molecular computers, including hardware, software, input and output, are molecules that interact in solution along a cascade of programmable chemical events.

"Our results show a novel, synthetic designed computing machine that computes iteratively and produces biologically relevant results," says lead researcher Prof. Ehud Keinan of the Technion Schulich Faculty of Chemistry. "In addition to enhanced computation power, this DNA-based transducer offers multiple benefits, including the ability to read and transform genetic information, miniaturization to the molecular scale, and the aptitude to produce computational results that interact directly with living organisms."

The transducer could be used on genetic material to evaluate and detect specific sequences, and to alter and algorithmically process genetic code. Similar devices, says Prof. Keinan, could be applied for other computational problems.

"All biological systems, and even entire living organisms, are natural molecular computers. Every one of us is a biomolecular computer, that is, a machine in which all components are molecules "talking" to one another in a logical manner. The hardware and software are complex biological molecules that activate one another to carry out some predetermined chemical tasks. The input is a molecule that undergoes specific, programmed changes, following a specific set of rules (software) and the output of this chemical computation process is another well defined molecule."

Also contributing to the research were postdoctoral fellows Dr. Tamar Ratner and Dr. Ron Piran of the Technion's Schulich Faculty of Chemistry, and Dr. Natasha Jonoska of the Department of Mathematics at the University of South Florida.

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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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Monkey teeth help reveal Neanderthal weaning

May 24, 2013 — Most modern human mothers wean their babies much earlier than our closest primate relatives. But what about our extinct relatives, the Neanderthals?

A team of U.S. and Australian researchers reports in the journal Nature May 22 that they can now use fossil teeth to calculate when a Neanderthal baby was weaned. The new technique is based in part on knowledge gained from studies of teeth from human infants and from monkeys at the California National Primate Research Center at the University of California, Davis.

Using the new technique, the researchers concluded that at least one Neanderthal baby was weaned at much the same age as most modern humans.

Just as tree rings record the environment in which a tree grew, traces of barium in the layers of a primate tooth can tell the story of when an infant was exclusively milk-fed, when supplemental food started, and at what age it was weaned, said Katie Hinde, professor of human evolutionary biology at Harvard University and an affiliate scientist at the UC Davis Primate Center. Hinde directs the Comparative Lactation Laboratory at Harvard and has conducted a three-year study of lactation, weaning and behavior among rhesus macaques at UC Davis.

The team was able to determine exact timing of birth, when the infant was fed exclusively on mother's milk, and the weaning process, from mineral traces in teeth. By studying monkey teeth and comparing them to center records, they could show that the technique was accurate almost to the day.

After validating the technique with monkeys, the scientists applied it to human teeth and a Neanderthal tooth. They found that the Neanderthal baby was fed exclusively on mother's milk for seven months, followed by seven months of supplementation -- a similar pattern to present-day humans. The technique opens up extensive opportunities to further investigate lactation in fossils and museum collections of primate teeth.

Although there is some variation among human cultures, the accelerated transition to foods other than mother's milk is thought to have emerged in our ancestral history due, in part, to more cooperative infant care and access to a more nutritious diet, Hinde said. Shorter lactation periods could mean shorter gaps between pregnancies and a higher rate of reproduction. However, there has been much debate about when our ancestors evolved accelerated weaning.

For the past few decades researchers have relied on tooth eruption age as a direct proxy for weaning age. Yet recent investigations of wild chimpanzees have shown that the first molar eruption occurs toward the end of weaning.

"By applying these new techniques to primate teeth in museum collections, we can more precisely assess maternal investment across individuals within species, as well as life history evolution among species," Hinde said.

Authors in addition to Hinde were: Christine Austin and Manish Arora, Icahn School of Medicine at Mount Sinai, New York, Harvard School of Public Health, and University of Sydney, Australia; Tanya Smith, Harvard University; Asa Bradman and Brenda Eskenazi, UC Berkeley; Renaud Joannes-Boyau, Southern Cross University, Lismore, Australia; David Bishop, Dominic Hare and Philip Doble, University of Technology Sydney, Australia.

The work was funded by the U.S. Environmental Protection Agency, U.S. National Institute of Environmental Health Sciences, U.S. National Science Foundation, Australian National Health and Medical Research Council, Australian Research Council and Harvard University.

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Why early human ancestors took to two feet

The researchers say our upright gait may have its origins in the rugged landscape of East and South Africa which was shaped during the Pliocene epoch by volcanoes and shifting tectonic plates.

Hominins, our early forebears, would have been attracted to the terrain of rocky outcrops and gorges because it offered shelter and opportunities to trap prey. But it also required more upright scrambling and climbing gaits, prompting the emergence of bipedalism.

The York research challenges traditional hypotheses which suggest our early forebears were forced out of the trees and onto two feet when climate change reduced tree cover.

The study, "Complex Topography and Human Evolution: the Missing Link," was developed in conjunction with researchers from the Institut de Physique du Globe in Paris. It is published in the journal Antiquity.

Dr Isabelle Winder, from the Department of Archaeology at York and one of the paper's authors, said: "Our research shows that bipedalism may have developed as a response to the terrain, rather than a response to climatically-driven vegetation changes.

"The broken, disrupted terrain offered benefits for hominins in terms of security and food, but it also proved a motivation to improve their locomotor skills by climbing, balancing, scrambling and moving swiftly over broken ground -- types of movement encouraging a more upright gait."

The research suggests that the hands and arms of upright hominins were then left free to develop increased manual dexterity and tool use, supporting a further key stage in the evolutionary story.

The development of running adaptations to the skeleton and foot may have resulted from later excursions onto the surrounding flat plains in search of prey and new home ranges.

Dr Winder said: "The varied terrain may also have contributed to improved cognitive skills such as navigation and communication abilities, accounting for the continued evolution of our brains and social functions such as co-operation and team work.

"Our hypothesis offers a new, viable alternative to traditional vegetation or climate change hypotheses. It explains all the key processes in hominin evolution and offers a more convincing scenario than traditional hypotheses."

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2013年5月24日星期五

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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SOI wafer supplier sees cash halved

LONDON – French semiconductor materials supplier Soitec SA, has reported a net loss of 209.5 million euro (about $270 million) on consolidated sales of 262.9 million euro (about $340 million), in its audited financial results for the year to March 31, 2013.

Soitec (Bernin, France) is the primary supplier of semiconductor-on-insulator (SOI) wafers for use in the fully-depleted SOI (FDSOI) manufacturing process that is being pioneered by STMicroelectronics NV (Geneva, Switzerland) at theCrolles wafer fab near Grenoble, France.

Soitec's net loss for 2012-2013 was 79.7 percent of sales and nearly four times larger than the net loss in the previous financial year. At the same time the consolidated sales declined by 18.7 percent compared with the previous year, which Soitec ascribed to declines in PC and related sales. Soitec reported cash resources of 130.1 million euro (about $168 million) at the end of March 2013 compared with cash resources of 259.8 million euro (about $336 million) at the end of March 2012.

The net loss included financial expenses and non-cash impairment charges, nonetheless the operating loss for the year was 123.0 million euro (about $160 million) compared with 45.9 million euro (about $60 million) in the previous year. Soitec said this was due to a significant decrease in demand for 300-mm diameter wafers, low asset utilization and continued investments in R&D.

Operating cash flow for the full year was negative 38.7 million euro (about $50 million) although was reduced to negative 1.3 million euro (about $1.7 million) in the second half of the financial year, Soitec reported.

When Soitec announced its unaudited results for the financial year in April 2013 the company indicated the outlook for sales in the coming financial year would remain soft. This is mainly due to cannibalization of PC-related markets by smartphones and tablet computers.

Related links and articles:

www.soitec.com

News articles:

Europe launches $12 billion chip support campaign

Europe backs FDSOI fabs

Intel moves forward with European 450-mm project

Soitec boosts production of silicon-on-sapphire wafers

MEMC introduces SOI wafers for FinFET over oxide

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White tiger mystery solved: Coat color produced by single change in pigment gene

"The white tiger represents part of the natural genetic diversity of the tiger that is worth conserving, but is now seen only in captivity," says Shu-Jin Luo of China's Peking University.

Luo, Xiao Xu, Ruiqiang Li, and their colleagues advocate a proper captive management program to maintain a healthy Bengal tiger population including both white and orange tigers. They say it might even be worth considering the reintroduction of white tigers into their wild habitat.

The researchers mapped the genomes of a family of 16 tigers living in Chimelong Safari Park, including both white and orange individuals. They then sequenced the whole genomes of each of the three parents in the family.

Those genetic analyses led them to a pigment gene, called SLC45A2, which had already been associated with light coloration in modern Europeans and in other animals, including horses, chickens, and fish. The variant found in the white tiger primarily inhibits the synthesis of red and yellow pigments but has little to no effect on black, which explains why white tigers still show characteristic dark stripes.

Historical records of white tigers on the Indian subcontinent date back to the 1500s, Luo notes, but the last known free-ranging white tiger was shot in 1958. That many white tigers were hunted as mature adults suggests that they were fit to live in the wild. It's worth considering that tigers' chief prey species, such as deer, are likely colorblind.

Captive white tigers sometimes do show abnormalities, such as crossed eyes, but Luo says any frailties are likely the responsibility of humans, who have inbred the rare tigers in captivity. With the causal gene identified, the researchers ultimately hope to explore the evolutionary forces that have maintained tigers in both orange and white varieties.

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Gold nanocrystal vibration captured on billion-frames-per-second film

May 23, 2013 — A billon-frames-per-second film has captured the vibrations of gold nanocrystals in stunning detail for the first time.

The film, which was made using 3D imaging pioneered at the London Centre for Nanotechnology (LCN) at UCL, reveals important information about the composition of gold. The findings are published in the journal Science.

Jesse Clark, from the LCN and lead author of the paper said: "Just as the sound quality of a musical instrument can provide great detail about its construction, so too can the vibrations seen in materials provide important information about their composition and functions."

"It is absolutely amazing that we are able to capture snapshots of these nanoscale motions and create movies of these processes. This information is crucial to understanding the response of materials after perturbation. "

Scientists found that the vibrations were unusual because they start off at exactly the same moment everywhere inside the crystal. It was previously expected that the effects of the excitation would travel across the gold nanocrystal at the speed of sound, but they were found to be much faster, i.e., supersonic.

The new images support theoretical models for light interaction with metals, where energy is first transferred to electrons, which are able to short-circuit the much slower motion of the atoms.

The team carried out the experiments at the SLAC National Accelerator Laboratory using a revolutionary X-ray laser called the "Linac Coherent Light Source." The pulses of X-rays are extremely short (measured in femtoseconds, or quadrillionths of a second), meaning they are able to freeze all motion of the atoms in any sample, leaving only the electrons still moving.

However, the X-ray pulses are intense enough that the team was able to take single snapshots of the vibrations of the gold nanocrystals they were examining. The vibration was started with a short pulse of infrared light.

The vibrations were imaged a short time later in 3D using the coherent diffraction imaging methods pioneered in LCN by the Robinson group. The 3D movies reveal in exquisite detail the distortions taking place within the nanocrystal, with the fastest vibrations repeating every 90 picoseconds.

Professor Robinson, also from the LCN and the group leader, said: "This work represents an impressive example of teamwork by about a hundred people at SLAC. The SLAC linear accelerator was built in 1957 in direct response to the news of Sputnik.

"After compelling 50 years of sensational high energy physics, that machine has been refitted as a laser by the addition of a 100m long array of magnets. This 3km-sized machine produces a beam which is focused onto a crystal smaller than a micron in a pulse so short that all motion of its atoms is frozen still."

Video: http://www.eurekalert.org/multimedia/pub/56841.php?from=240381

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Drug reverses Alzheimer's disease deficits in mice

The research, funded by the National Institutes of Health's National Institute on Aging and Alzheimer's Association, reviewed previously published findings on the drug bexarotene, approved by the U.S. Food and Drug Administration for use in cutaneous T cell lymphoma. The Pitt Public Health researchers were able to verify that the drug does significantly improve cognitive deficits in mice expressing gene mutations linked to human Alzheimer's disease, but could not confirm the effect on amyloid plaques.

"We believe these findings make a solid case for continued exploration of bexarotene as a therapeutic treatment for Alzheimer's disease," said senior author Rada Koldamova, M.D., Ph.D., associate professor in Pitt Public Health's Department of Environmental and Occupational Health.

Dr. Koldamova and her colleagues were studying mice expressing human Apolipoprotein E4 (APOE4), the only established genetic risk factor for late-onset Alzheimer's disease, or APOE3, which is known not to increase the risk for Alzheimer's disease, when a Case Western Reserve University study was published last year stating that bexarotene improved memory and rapidly cleared amyloid plaques from the brains of Alzheimer's model mice expressing mouse Apolipoprotein E (APOE). Amyloid plaques consist of toxic protein fragments called amyloid beta that seem to damage neurons in the brain and are believed to cause the associated memory deficits of Alzheimer's disease and, eventually, death.

Bexarotene is a compound chemically related to vitamin A that activates Retinoic X Receptors (RXR) found everywhere in the body, including neurons and other brain cells. Once activated, the receptors bind to DNA and regulate the expression of genes that control a variety of biological processes. Increased levels of APOE are one consequence of RXR activation by bexarotene. The Pitt researchers began studying similar compounds a decade ago.

"We were already set up to repeat the Case Western Reserve University study to see if we could independently arrive at the same findings," said co-author Iliya Lefterov, M.D., Ph.D., associate professor in Pitt Public Health's Department of Environmental and Occupational Health. "While we were able to verify that the mice quickly regained their lost cognitive skills and confirmed the decrease in amyloid beta peptides in the interstitial fluid that surrounds brain cells, we did not find any evidence that the drug cleared the plaques from their brains."

The Pitt researchers postulate that the drug works through a different biological process, perhaps by reducing soluble oligomers which, like the plaques, are composed of the toxic amyloid beta protein fragments. However, the oligomers are composed of smaller amounts of amyloid beta and, unlike the plaques, are still able to "move."

"We did find a significant decrease in soluble oligomers," said Dr. Koldamova. "It is possible that the oligomers are more dangerous than the plaques in people with Alzheimer's disease. It also is possible that the improvement of cognitive skills in mice treated with bexarotene is unrelated to amyloid beta and the drug works through a completely different, unknown mechanism."

In the Pitt experiments, mice with the Alzheimer's gene mutations expressing human APOE3 or APOE4 were able to perform as well in cognitive tests as their non-Alzheimer's counterparts 10 days after beginning treatment with bexarotene. These tests included a spatial test using cues to find a hidden platform in a water maze and a long-term memory test of the mouse's ability to discriminate two familiar objects following introduction of a third, novel object.

Bexarotene treatment did not affect the weight or general behavior of the mice. The drug was equally effective in male and female mice.

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Molecule that triggers sensation of itch discovered

May 23, 2013 — Scientists at the National Institutes of Health report they have discovered in mouse studies that a small molecule released in the spinal cord triggers a process that is later experienced in the brain as the sensation of itch.

The small molecule, called natriuretic polypeptide b (Nppb), streams ahead and selectively plugs into a specific nerve cell in the spinal cord, which sends the signal onward through the central nervous system. When Nppb or its nerve cell was removed, mice stopped scratching at a broad array of itch-inducing substances. The signal wasn't going through.

Because the nervous systems of mice and humans are similar, the scientists say a comparable biocircuit for itch likely is present in people. If correct, this start switch would provide a natural place to look for unique molecules that can be targeted with drugs to turn off the sensation more efficiently in the millions of people with chronic itch conditions, such eczema and psoriasis.

The paper, published online in the journal Science, also helps to solve a lingering scientific issue. "Our work shows that itch, once thought to be a low-level form of pain, is a distinct sensation that is uniquely hardwired into the nervous system with the biochemical equivalent of its own dedicated land line to the brain," said Mark Hoon, Ph.D., the senior author on the paper and a scientist at the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health.

Hoon said his group's findings began with searching for the signaling components on a class of nerve cells, or neurons, that contain a molecule called TRPV1. These neurons, with their long nerve fibers extending into the skin, muscle, and other tissues, help to monitor a range of external conditions, from extreme temperature changes to detecting pain.

Yet little is known about how these neurons recognize the various sensory inputs and, like sorting mail, know how to route them correctly to the appropriate pathway to the brain.

To fill in more of the details, Hoon said his laboratory identified in mice some of the main neurotransmitters that TRPV1 neurons produce. A neurotransmitter is a small molecule that neurons selectively release when stimulated, like a quick pulse of water from a faucet, to communicate sensory signals to other nerve cells.

The scientists screened the various neurotransmitters, including Nppb, to see which ones corresponded with transmitting sensation.

"We tested Nppb for its possible role in various sensations without success," said Santosh Mishra, lead author on the study and a researcher in the Hoon laboratory. "When we exposed the Nppb-deficient mice to several itch-inducing substances, it was amazing to watch. Nothing happened. The mice wouldn't scratch."

Further experiments established that Nppb was essential to initiate the sensation of itch, known clinically as pruritus. Equally significant, the molecule was necessary to respond to a broad spectrum of pruritic substances. Previous research had suggested that a common start switch for itch would be unlikely, given the myriad proteins and cell types that seemed to be involved in processing the sensation.

Hoon and Mishra turned to the dorsal horn, a junction point in the spine where sensory signals from the body's periphery are routed onward to the brain. Within this nexus of nerve connections, they looked for cells that expressed the receptor to receive the incoming Nppb molecules.

"The receptors were exactly in the right place in the dorsal horn," said Hoon, the receptor being the long-recognized protein Npra. "We went further and removed the Npra neurons from the spinal cord. We wanted to see if their removal would short-circuit the itch, and it did."

Hoon said this experiment added another key piece of information. Removing the receptor neurons had no impact on other sensory sensations, such as temperature, pain, and touch. This told them that the connection forms a dedicated biocircuit to the brain that conveys the sensation of itch.

But the scientists had stepped into a conundrum. Previous reports had suggested that another neurotransmitter called GRP might initiate itch. If that wasn't the case, where did GRP fit into the process?

They tested the receptor neurons that express GRP, finding the previous reports were correct about this molecule relaying the signal to the central nervous system. GRP just enters the picture after Nppb already has set the sensation in motion.

Based on these findings, Nppb would seem to be an obvious first target to control itch. But that's not necessarily the case. Nppb also is used in the heart, kidneys, and other parts of the body, so attempts to control the neurotransmitter in the spine has the potential to cause unwanted side effects.

"The larger scientific point remains," said Hoon. "We have defined in the mouse the primary itch-initiating neurons and figured out the first three steps in the pruritic pathway. Now the challenge is to find similar biocircuitry in people, evaluate what's there, and identify unique molecules that can be targeted to turn off chronic itch without causing unwanted side effects. So, this is a start, not a finish."

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