|
RESEARCH ROUNDUP
Unemployment,
Rents Push Families to Homelessness The study, published in Cityscape: A Journal of Policy and Development Research by the U.S. Department of Housing and Urban Development, also looked at other factors, including welfare reform. Dr. Culhane's team used data collected by the Office of Emergen-cy Shelter and Services, Philadelphia's central management agency for homeless emergency services. To see if shelter utilization changed signifi-cantly after March 1997, when major welfare reform was implemented in PA, they looked at the number of families admitted by family size, race, age of household head, income, household-head disability and average length of stay. The researchers also checked these factors after three, six, nine and twelve months of welfare-reform implementation. The researchers looked at whether an increase in shelter admittance could be tied to an expected decline in the state welfare caseloads as the new Temporary Assistance for Needy Families guidelines took effect. Under TANF, lifetime benefits are capped at five years, and those receiving benefits have two years to find employment before being cut off. The researchers also found a small but negative relationship between self-reported substance abuse in the household heads and shelter admis-sion, as well as a small but positive relationship between household heads with a disability and shelter use. Sleep
Deprivation Impairs Memory Consolidation The researchers also determined that the five hours following learning are crucial for memory consolidation; mice deprived of sleep five to 10 hours after learning a task showed no memory impairment. The results are reported in the May/June issue of the journal Learning & Memory. "Memory consolidation happens over a period of hours after training for a task, and certain cellular processes have to occur at precise times," said senior author Dr. Ted Abel, assistant professor of biology at Penn. "We set out to pinpoint the specific window of time and area of the brain that are sensitive to sleep deprivation after learning." Dr. Abel and his colleagues found that sleep deprivation zero to five hours after learning appeared to impair spatial orientation and recognition of physical surroundings, known as contextual memory. Recollection of specific facts or events, known as cued memory, was not affected. Because the brain's hippocampus is key to contextual memory but not cued memory, the findings provide new evidence that sleep helps regulate neuronal function in the hippocampus. "It has been suggested that sleep serves a variety of physiological functions, ranging from energy conservation to refreshing the immune system," Dr. Abel said. "Another important hypothesis is that sleep regulates neuronal function during memory consolidation. Our findings provide support for this theory, and, by implicating hippocampal-dependent tasks during a specific time window, we have taken an initial step in clarifying the neural effects of sleep deprivation." Dr. Abel's co-authors are Laurel A. Graves and Allan I. Pack of Penn's School of Medicine and Penn undergraduate Elizabeth A. Heller. The work was supported by the NIH, the Whitehall Foundation, the Universi-ty of Pennsylvania Research Foundation and the Mental Retardation and Developmental Disabilities Research Center at CHOP. Deadly
'Drug Corner' Moves to Your Computer In fact, if you search for "no prescription codeine" through one of the standard computer-search systems, the odds are almost fifty-fifty that the first site you hit will provide an instant opportunity to buy drugs illegally. That finding by researchers at Penn's School of Medicine was published in the August 20 issue of the Journal of the American Medical Association. "This is unprecedented access to opiates, and it is relatively undocu-mented," said Dr. Robert F. Forman, assistant professor of psychology in psychiatry, principal author of the study, and a member of Penn's Treat-ment Research Institute. Using Google.com, a commonly used computer search engine, Dr. Forman and his Penn colleague, Ovgu Kaynack, found that 53 of the first 100 web-page links generated by typing in the term "no prescription codeine" were sites that offered to sell directly or indirectly opiate medication without a prescription, and 35 of those sites also sold barbituates, benzodiazepines, hallucinogens and other prescription stimulants. In many instances, Dr. Forman said, the only information necessary for purchasing drugs through the sites were a shipping address and a pay-ment method. "These websites present a significant risk to public health. The uncon-trolled access to prescription drugs can lead to an increase in addiction and overdose deaths, and yet children preparing a report for school may inadvertently stumble upon a portal that leads them to illegal drugs," Dr. Forman said. "There is evidence that prescription drug use among young people is increasing. We need to discern whether law enforcement officials in the United States can work effectively against drug sites that operate out of other countries, some of which permit the sale of opiates." Dr. Forman's work is supported by the National Institute on Drug Abuse Clinical Trials Network. Discovery
of Solar System 'Fossils' The study's big surprise is that so few Kuiper Belt members were dis-covered. With Hubble's exquisite resolution, Dr. Gary Bernstein, associ-ate professor of physics and astronomy, and his co-workers expected to find at least 60 Kuiper Belt members as small as 10 miles in diameter –but only three were discovered. Dr. Bernstein and his colleagues used Hubble to look for planetesimals that are much smaller and fainter than can be seen from ground-based telescopes. Hubble's Advanced Camera for Surveys was pointed at a region in the constellation Virgo over a 15-day period in January and February. A bank of 10 computers on the ground worked for six months searching for faint moving spots in the Hubble images. The three small objects the astronomers spotted–given the prosaic names 2003 BF91, 2003 BG91 and 2003 BH91–range in size from 15 to 28 miles and are the smallest objects ever found beyond Neptune. At their current locations, these objects are a billion times fainter than the dimmest objects visible to the naked eye. But an icy body of this size that escapes the Kuiper Belt to wander near the sun can become visible from Earth as a comet as the wandering body starts to evaporate and form a surrounding cloud. Astronomers are probing the Kuiper Belt because the region offers a window on the early history of our solar system. The planets formed more than 4 billion years ago from a cloud of gas and dust that surrounded the infant sun. Microscopic bits of ice and dust stuck together to form lumps that grew from pebbles to boulders to city-or continent-sized planetesi-mals. The known planets and moons are the result of collisions between planetesimals. In most of the solar system, all of the planetesimals have either been absorbed into planets or ejected into interstellar space, destroying the traces of the early days of the solar system. Astronomers now use the Kuiper Belt to learn about the history of the solar system, much as paleontologists use fossils to study early life. Each event that affected the outer solar system–such as possible gravitational disturbances from passing stars or long-vanished planets–is frozen into the properties of the Kuiper Belt members that we see today. If the Hubble telescope could search the entire sky, it would find per-haps a half-million planetesimals, but, if collected into a single planet, they would be only a few times larger than Pluto. The new Hubble observations, combined with the latest ground-based Kuiper Belt surveys, rein-force the idea that Pluto itself and its moon Charon are just large Kuiper Belt members. Why the Kuiper Belt planetesimals did not form a larger planet and why there are fewer small planetesimals than expected are questions that will be answered with further study of the Kuiper Belt. This will help to understand how planets might have formed around other stars as well. The new results from Hubble were reported by Dr. Bernstein and Dr. David Trilling, Penn; Renu Malhotra, University of Arizona; Lynne Allen, University of British Columbia; Michael Brown, California Institute of Technology; and Matthew Holman, Harvard-Smithsonian Center for As-trophysics. The results have been submitted to the Astronomical Journal for publication.
|
|
