January 10, 2007, 9:26 PM CT

Female Ducks Negotiate Joint Rearing

Female eider ducks are well known to team up and share the work of rearing ducklings, but it now appears that they also negotiate not only how much effort each puts into the partnership, but also profit-sharing. An international group of scientists used a long-running study of the eider population in a Finnish archipelago to test predictions about how each hen seeks to maximize her benefits from the partnership without making it so unattractive that other hens withdraw their participation.

As hens arrive at the rearing-area with their ducklings, a period of intense socializing ensues. The hens then sort themselves into cliques - pairs, trios, or quartets - with each hen in a group assuming a distinct role.

"Waterfowl have a reputation as being none-too-bright, but we think they are careful, sophisticated bargainers," says team leader Markus Öst (University of Helsinki). "The socializing during the period prior to group formation is devoted to the searching for and negotiating with a suitable partner".

As a group, each hen's ducklings are kept warm, led to food, and fiercely defended against predatory gulls - all tasks for which central positions in the brood are the best and safest. Though the ducklings appear identical to human observers, hens can clearly recognize them and carefully manage their ducklings' locations in the joint brood, apparently according to an agreement worked out with the other hens.........

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January 10, 2007, 8:20 PM CT

Beavers Helping Frogs

The humble beaver, besides claiming a spot of honour on the Canadian nickel, is also helping fellow species survive.

Though considered a pest because of the culvert-clogging dams it builds on streams, the beaver is an ally in conserving valuable wetland habitat for declining amphibian populations, a University of Alberta study shows.

The study, conducted in the boreal forests of west-central Alberta, showed that frog and toad choruses are only present on streams where beaver dams are present. While surveying the calls of male frogs and toads engaged in acoustic displays for females, researchers recorded approximately 5,000 boreal chorus frogs, wood frogs and western toads at 54 beaver ponds over a two-year period. Pitfall traps on beaver ponds captured 5.7 times more newly metamorphosed wood frogs, 29 times more western toads and 24 times more boreal chorus frogs than on nearby free-flowing streams.

The study identifies beaver as a valuable 'surrogate species', said University of Alberta researchers Dr. Cam Stevens (lead author) and Dr. Cindy Paszkowski. The work is published in the January 2007 issue of Biological Conservation. Surrogate species can be indicators of changes to the environment caused directly or indirectly by human activities, population changes in other species, or they can act as 'umbrellas' protecting a large number of naturally co-occurring species.........

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January 9, 2007, 9:21 PM CT

Brightest Supernova

Twenty years ago next month, the closest and brightest supernova in four centuries lit up the southern sky, wowing astronomers and the public alike.

Ongoing observations of the exploded star, called supernova 1987A, provided important tests for theories of how stars die, but it also raised some new questions. Principal among these was how a bizarre, triple-ring nebula surrounding the supernova - ejected by the star a few thousand years before it exploded - originated. Astronomers devised a complicated theory that, within a relatively short period of time, the original star, a red supergiant, merged with a companion and started spinning rapidly, then underwent a transition to a blue supergiant, and finally exploded.

University of California, Berkeley, astronomer Nathan Smith has proposed a different theory for the origin of the nebula, arguing instead that SN1987A's progenitor star may have been in a class of unstable blue supergiant stars, called luminous blue variables, which eject material from their surfaces in recurring, volcano-like eruptions before they finally die in a supernova explosion.

Smith recently discovered two such blue supergiant stars with nebulae closely resembling the peculiarly shaped cloud of dust and gas around SN1987A. A third such nebula was already known.........

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January 9, 2007, 8:26 PM CT

Letting The Blind See

Kristina Narfstrom, a University of Missouri-Columbia veterinary ophthalmologist, has been working with a microchip implant to help blind animals "see." According to Narfstrom, the preliminary results are promising.

"About one in 3,500 people worldwide is affected with a hereditary disease, retinitis pigmentosa, that causes the death of retinal cells and, eventually, blindness," Narfstrom said. "Our current study is aimed at determining safety issues in regard to the implants and to further develop surgical techniques. We also are examining the protection the implants might provide to the retinal cells that are dying due to disease progression with the hope that natural sight can be maintained much longer than would be possible in an untreated patient".

Narfstrom, the Ruth M. Kraeuchi-Missouri Professor in Veterinary Ophthalmology, is working primarily with Abyssinian and Persian cats that are affected with hereditary retinal blinding disease. The cat's eye is a good model to use for this type of research because it is very similar to a human eye in size and construction, so surgeons can use the same techniques and equipment. Cats also share many of the same eye diseases with humans. The Abyssinian cats that Narfstrom is working with typically start to lose their sight when they are around one or two years old and are completely blind by age four.........

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January 9, 2007, 8:19 PM CT

Finding Patterns Of Importance

Dartmouth engineers George Cybenko and Vincent Berk think that PQS, or process query systems, are the way to go to make sense of the huge volume of data we collect each day from computer network monitors, video surveillance cameras, financial transaction records, databases of email exchanges, etc. The duo present their case in a paper published in this month's IEEE Computer, the flagship magazine of the Institute of Electrical and Electronics Engineers' Computer Society.

"PQS closes the gap between gathering a tremendous amount of valuable data and figuring out what the data means," says Cybenko, the Dorothy and Walter Gramm Professor of Engineering at Dartmouth's Thayer School of Engineering.

PQS has been an evolving algorithmic and software framework for the past few years. Cybenko and Berk say that PQS is a useful and incredibly powerful tool to quickly analyze credit reports for ID theft, discover attacks on computer networks, and measure activity at, say, national borders, mall parking lots, or wildlife refuge areas. According to Cybenko, "PQS can do for discrete, categorical data analysis problems what classical times series analysis did for finance and control systems where the data are numerical".

It is based on the premise that sensed environments, be they computer networks, email traffic, or high-security buildings, all consist of processes with distinct states, dynamics, and observables. PQS works to detect and understand the changes or irregularities in these processes. The PQS software is easily installed with the sensor equipment to collect, monitor, and sort out a great deal of data.........

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January 9, 2007, 8:15 PM CT

How Some Invasive Plants Gain a Foothold?

University of California, Riverside genetics Professor Norman Ellstrand led a team of researchers whose findings suggest that harnessing the sexual requirements of some plants can help control the establishment of invasive species.

Using the California wild radish as their model, Ellstrand and graduate student Caroline Ridley at the UCR Department of Botany and Plant Sciences co-authored the research study titled Population size and relatedness affect fitness of self-incompatible invasive plants, published in the Dec. 29 edition of the Proceedings of the National Academy of Sciences. The current article originated from a doctoral dissertation project by former UCR graduate student Diane Elam. Fellow graduate student Karen Goodell also worked on the project. Elam is now with the U.S. Fish and Wildlife Service's Sacramento office. Karen Goodell now teaches at Ohio State University.

The experiment involved population groups ranging in size from two to 20 plants and was carried out at UCR's Agricultural Experiment Station. The experiment examined whether a biological phenomenon known as the Allee effect could be used to battle the spread of invasive plants. The Allee effect, named after ecologist W.C. Allee, says that the smaller and sparser a given population, the harder and slower it is for that population to establish itself and expand its range.........

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January 9, 2007, 5:00 AM CT

Tracing Agent, Ultrasound Combo And Cancer

An inexpensive tracing agent used in combination with ultrasound can pinpoint how effectively drugs targeting pancreatic cancer work, researchers at UT Southwestern Medical Center have demonstrated for the first time.

The study, involving human pancreatic tumor cells implanted in mice, opens a new avenue for real-time imaging of a patient's response to cancer therapies. It appears in the Jan. 1 issue of the journal Clinical Cancer Research.

The UT Southwestern research team focused on pancreatic cancer because it is one of the deadliest cancers, characterized by extensive local invasion and metastasis to the liver, said Dr. Rolf Brekken, assistant professor of surgery and pharmacology and the study's senior author. The five-year survival rate ranges from only 1 percent to 4 percent for patients diagnosed with the most severe form of cancer of the pancreas called pancreatic andenocarcinoma.

"The current best therapy - including surgery, radiation and chemotherapy - has done little to alter cancer-related deaths of these patients, emphasizing the need for more effective treatment," said Dr. Brekken, a researcher at the Nancy B. and Jake L. Hamon Center for Therapeutic Oncology Research at UT Southwestern.

The research team examined how pancreatic tumor cells respond to an experimental anti-cancer agent that targets vascular endothelial growth factor (VEGF), a protein responsible for triggering the development of blood vessels that deliver nutrients and oxygen to tumors, enabling them to grow and spread. Drugs that target VEGF are in a class called anti-angiogenic agents that are designed to choke tumor growth by reducing the number of blood vessels feeding the cancer.........

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January 7, 2007, 9:21 PM CT

Rapid, Low-Cost DNA Testing

Professor Lewis Rothberg of the University of Rochester Chemistry Department received a NYSTAR grant in August 2006 to continue working on a recent discovery by Huixiang Li, a research associate in his group: how to rapidly test DNA to improve our health and make sure we're drinking clean water and eating uncontaminated food. In fact, his new method can be used to help forensics labs identify criminals, test ponds and pools before children swim in them, and identify harmful genetic sequences in medical research, to name only a few applications. Rothberg's innovative procedure quickly and inexpensively identifies genetic sequences in any sample of DNA.

The technology is a novel fluorescent DNA screening assay, which rapidly determines whether specific DNA target sequences are present in an analyte. In simple terms, the analyte contains the DNA target sequences as well as other DNA sequences, and the assay filters out only the targets. Professor Rothberg's assay is based on the electrostatic properties of DNA.

The principle underlying the method is that single-stranded DNA and double-stranded DNA have significantly different affinities for attaching to ionically charged gold nanoparticles. Because ions have electric charges, having gained or lost electrons, they attract their opposites. An anion with a negative electric charge will attract positive charges, a cation with a positive charge will attract negative charges. Single-stranded DNA adsorbs on negatively charged citrate ions on the gold nanoparticles while double-stranded DNA does not. Given that both single-stranded and double-stranded DNA are (nominally) negatively charged, this proven phenomenon intrigues the research group.........

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January 7, 2007, 7:05 AM CT

Foods High In Calcium, Vitamin D And Prevention Of Osteoporosis

The Food and Drug Administration has issued a new and amended health claims with regard to consumption of foods that are rich in vitamin D and calcium. This new statement is meant to educate consumers the value of foods high in calcium and vitamin D for reducing the risk of osteoporosis. The National Dairy Council acknowledges and supports the body of scientific evidence that backs the proposed claim, which indicates that a lifestyle that includes a well-balanced diet with adequate calcium and vitamin D, and physical activity, helps reduce the risk of osteoporosis.

"The proposed claim provides a clearer way to communicate the benefits of calcium and vitamin D in bone health," says Ann Marie Krautheim, registered dietitian and senior vice president of nutrition and health promotion at the National Dairy Council. "We hope the simplified language will help consumers better understand the importance of three daily servings of dairy to obtain these nutrients and reduce the risk of osteoporosis".

Together, milk, cheese and yogurt provide excellent sources of calcium and vitamin D. In addition to calcium and vitamin D, the U.S. Surgeon General's Report on Bone Health and Osteoporosis recognizes the role of a number of other nutrients in dairy foods, including magnesium, phosphorus, potassium and protein, that work together to help protect bones. The report also recognizes the importance of regular physical activity in contributing to bone health.........

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December 31, 2006, 7:52 PM CT

Ground Spider Diversity

None of Takesha Henderson's discoveries are named Charlotte, but they are weaving a new chapter in Texas entomology. Her graduate studies at Texas A&M University have led to the discovery of 25 new spiders in Brazos County and one species found for the first time in Texas.

In research sponsored by the National Science Foundation, Henderson, who is earning a master's degree, has been studying ground spider diversity, distribution and abundance in the 515-acre Lick Creek Park south of College Station.

She has caught 1,000 specimens in 111 species over two years. The most common were several species of wolf spiders, she said.

A total of 989 species of spiders have been identified in Texas; 280 of these are found in Brazos County.

Henderson set out pitfall traps - made of plastic cups, funnels and animal-safe antifreeze - to collect the spiders. A variety of sites - including upland woods, post oak woodlands and an area disturbed by a high level of human activity - were chosen.

The collected samples are being identified and placed in the Texas A&M Insect Collection, department of entomology.

Dr. Marvin Harris, Texas Agricultural Experiment Station entomologist and chair of Henderson's master's committee, began working with her when she was an undergraduate.........

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