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News of the Week:
The
Cosmos' Fate: World Without End
Two new studies provide strong hints that the universe may expand forever.
References:
Garnavich, P.M., et al. Preprint. Constraints on cosmological models from Hubble Space Telescope observations of high-z supernovae. Astrophysical Journal Letters.
Perlmutter, S., et al. 1998. Discovery of a supernova explosion at half the age of the universe and its cosmological implications. Nature 391(Jan. 1).
Further Readings:
Branch, D. 1998. Density and destiny. Nature 391(Jan. 1).
Cowen, R. 1997. From soup to us. Science News 151(June 7):354.
Zeroing in on an infinite number of primes
Mathematicians have proved there are infinitely many primes among whole numbers of the form a^2 + b^4.
References:
Friedlander, J., and H. Iwaniec. In press. Asymptotic sieve for primes. Annals of Mathematics.
______. In press. The polynomial x^2 + y^4 captures its primes. Annals of Mathematics.
Further Readings:
Friedlander, J., and H. Iwaniec. 1997. Using a parity-sensitive sieve to count prime values of a polynomial. Proceedings of the National Academy of Sciences 94(Feb. 18):1054. Available at http://www.pnas.org/cgi/content/abstract/94/4/1054.
Peterson, I. 1997. Prize offered for solving number conundrum. Science News 152(Nov. 15):310.
______. 1997. Prime gaps. Science News Online (May 31).
______. 1996. Prime theorem of the century. Science News Online (Dec. 21).
Ribenboim, P. 1996. The New Book of Prime Number Records. New York: Springer-Verlag.
A chemical foam converts asbestos fireproofing materials to nontoxic but still protective minerals.
Further Readings:
Fackelmann, K. 1988. DNA rides along as asbestos enters cells. Science News 136(Oct. 29):278.
Loupe, D.E. 1989. Asbestos fiber shape may trigger radicals. Science News 136(Sept. 9):167.
Raloff, J. 1991. Cell videos catch asbestos in the act. Science News 140(Sept. 21):180.
______. 1990. More jobs linked to asbestos hazards. Science News 137(June 16):373.
______. 1988. EPA finds widespread asbestos hazard. Science News 133(March 5):150.
______. 1987. Asbestos subpoena quashed. Science News 132(July 25):55.
Xenon injects images with brightness
Injected into the body, the inert gas xenon can enhance magnetic resonance images.
References:
Goodson, B.M. . . . T.F. Budinger, G. Navon, and A. Pines. 1997. In vivo NMR and MRI using injection delivery of laser-polarized xenon. Proceedings of the National Academy of Sciences 94(Dec. 23):14725.
Further Readings:
1996. A sharper magnetic window into the body. Science News 149(May 4):282.
Pennisi, E. 1994. Breathe (xenon) deeply to see lungs clearly. Science News 146(July 30):70.
Swanson, S.D., et al. 1997. Brain MRI with laser-polarized 129Xe. Magnetic Resonance in Medicine 38(November):695.
Wilson, E.K. 1996. Hyperpolarized gases set NMR world spinning. Chemical & Engineering News Dec. 23:21.
An interactive Web site containing a xenon respiration model can be found at http://ric.uthscsa.edu/staff/charlesmartinphd.html, and human lung images using helium 3 can be viewed at http://avery.med.virginia.edu/~tm6a/helium.html. Visit http://pupgg.princeton.edu/~gphysics/research/Happer_William.html for an introduction to the work of William Happer, a pioneer of optical pumping.
Mongolian dinosaurs give up sandy secrets
Geologists propose that recently uncovered dinosaurs lived in rolling meadows, rather than deserts, more than 70 million years ago.
References:
Loope, D.B., et al. 1998. Life and death in a Late Cretaceous dune field, Nemegt basin, Mongolia. Geology 25(January):27.
Further Readings:
Fastovsky, D.E., et al. 1997. The paleoenvironments of Tugrikin-Shireh (Gobi Desert, Mongolia) and aspects of the taphonomy and paleoecology of Protoceratops (Dinosauria: Ornithishichia). Palaios 12(February):59.
Monastersky, R. 1996. Nesting dinosaur discovered in Mongolia. Science News 149(Jan. 6):7.
DNA tests find phony seal penises
Material sold as seal penises for use as aphrodisiacs includes parts of species that aren't even close to being seals.
References:
Malik, S., et al. 1997. Pinniped penises in trade: A molecular-genetic investigation. Conservation Biology 11(December):1365.
Further Readings:
Baker, C.S., and S.R. Palumbi. 1994. Which whales are hunted? A molecular genetic approach to monitoring whaling. Science 265:1538.
A surprising encounter of the NEAR kind
Pictures and data obtained during last summer's flyby of asteroid 253 Mathilde indicate that the carbon-rich, heavily cratered body has an extremely low density.
References:
Veverka, J., et al. 1997. NEAR's flyby of 253 Mathilde: Images of a C asteroid. Science 278(Dec. 19):2109.
Yeomans, D.K., et al. 1997. Estimating the mass of asteroid 253 Mathilde from tracking data during the NEAR flyby. Science 278(Dec. 19):2106.
Further Readings:
Cowen, R. 1997. Waltzing past Mathilde. Science News 152(July 12):29.
Gene pushes cells into forced retirement
A newly identified gene induces cancer cells to enter senescence, a nondividing state that might play a role in aging.
References:
Bertram, M.J., et al. 1997. Isolation of the cell senescence gene on human chromosome 4. Meeting of the American Society for Cell Biology. Washington, D.C.
Further Readings:
Travis, J. 1995. End games. Science News 148(Nov. 25):362.
Research Notes:
Astronomy
Europa's salty surface
Evidence of magnesium sulfate on the surface of Europa lends further support to the notion that this Jovian moon recently had and might still harbor an underground ocean.
References:
McCord, T.B., et al. 1997. Composition of the icy Galilean satellite surfaces from the Galileo NIMS investigation. Meeting of the American Geophysical Union. San Francisco.
Further Readings:
Cowen, R. 1997. C'est la vie. Science News 152(Nov. 1):284.
Fossils from Mars: Point, counterpoint
Researchers continue to debate whether a rock from Mars contains tiny fossils of primitive bacteria.
References:
Bradley, J.P., R.P. Harvey, and H.Y. McSween Jr. 1997. No 'nanofossils' in Martian meteorite. Nature 390(Dec. 4):454.
McKay, D.S. . . . K. Thomas-Keprta, and H. Vali. 1997. No 'nanofossils' in Martian meteorite (Reply). Nature 390(Dec. 4):455.
Further Readings:
Cowen, R. 1996. Searching for life in a Martian meteorite. Science News 150(Dec. 14):380.
Behavior
Evolution of attention
Symptoms of attention-deficit/hyperactivity disorder may sometimes represent adaptive responses to certain environments.
References:
Jensen, P.S., et al. 1997. Evolution and revolution in child psychiatry: ADHD as a disorder of adaptation. Journal of the American Academy of Child and Adolescent Psychiatry 36(December):1672.
Leckman, J.F. 1997. Commentary in the Journal of the American Academy of Child and Adolescent Psychiatry 36(December):1680.
Further Readings:
Bower, B. 1993. Hyperactivity grows into adult problems. Science News 144(July 31):70.
Magentic mood brightener
A pilot study suggests that magnetic stimulation of the brain improves the mood of people suffering from major depression.
References:
George, M.S., et al. 1997. Mood improvement following daily left prefrontal repetitive transcranial magnetic stimulation in patients with depression: A placebo-controlled crossover trial. American Journal of Psychiatry 154(December):1572.
Biology
Frogs that talk through their ears
The North American bullfrog uses its ears as amplifiers to broadcast its commanding croak.
References:
Purgue, A.P. 1997. Tympanic sound radiation in the bullfrog Rana catesbeiana. Journal of Comparative Physiology A. 181(November):438.
Rand, A.S., and R. Dudley. 1993. Frogs in helium: The anuran vocal sac is not a cavity resonator. Journal of Comparative Physiological Zoology 66(November):793.
Frog real estate: More than location
Proposed fixes for fragmented habitat may help one frog species but not another in the same forest.
References:
Marsh, D.M., and P.B. Pearman. 1997. Effects of habitat fragmentation on the abundance of two species of Leptodactylid frogs in an Andean montane forest. Conservation Biology 11(December):1323.
Biomedicine
Mammograms get boost for women over 40
Women who get regular mammograms in their 40s are less likely to die of breast cancer, a Swedish study shows.
References:
Bjurstam, N., et al. 1997. The Gothenburg breast screening trial. Cancer 80(Dec. 1):2091.
Further Readings:
Alexander, F.E., et al. 1994. The Edinburgh randomized trial of breast cancer screening: Results after 10 years of follow-up. British Journal of Cancer 70:542.
Fackelmann, K. 1997. Update on the mammogram debate. Science News 151(April 19):240.
______. 1997. The question of regular mammograms. Science News 151(Feb. 22):124.
Feig, S.A. Increased benefit from shorter screening mammography intervals for women ages 40-49 years. Cancer 80(Dec. 1):2035.
Salzmann, P., K. Kerlikowske, and K. Phillips. 1997. Cost-effectiveness of extending screening mammography guidelines to include women 40 to 49 years of age. Annals of Internal Medicine 127(Dec. 1):955.
Role of cancer mutation scrutinized
A genetic mutation thought to predispose people to colorectal cancer didn't have that effect when scientists focused on families with histories of breast and ovarian cancer.
References:
Petrukhin, L. . . . A.K. Godwin. 1997. The I1307K APC mutation does not predispose to colorectal cancer in Jewish Ashkenazi breast and breast-ovarian cancer kindreds. Cancer Research 57(Dec. 15):5480.
Further Readings:
Laken, S.J., et al. Familial colorectal cancer in Ashkenazim due to a hypermutable tract in APC. Nature Genetics 17:79.
Seppa, N. 1997. Novel gene defect for colorectal cancer. Science News 152(Aug. 30):133.
Articles:
From the moon to Mars and beyond
Ranging from a close-up tour of the moon to an orbiting telescope searching for distant galaxies, the majority of missions scheduled for 1998 are diminutive.
Further Readings:
Further information is available about the Advanced X-ray Astrophysics Facility at http://xrtpub.harvard.edu; about the Tomographic Experiment using Radiative Recombinative Ionospheric EUV and Radio Sources (TERRIERS), at http://net.bu.edu/terriers.html; about Mars 98 Orbiter, at http://mars.jpl.nasa.gov/msp98; about Far Ultraviolet Spectroscopic Explorer, at http://fuse.pha.jhu.edu; and about Lunar Prospector, at http://lunar.arc.nasa.gov/science.
Children of the C4 World
Did a decline in carbon dioxide concentrations spur our evolution?
A change in the atmosphere may have altered global vegetation and mammalian species 8 million years ago.
References:
Cerling, T.E., et al. 1997. Global vegetation change through the Miocene/Pliocene boundary. Nature 389(Sept. 11):153.
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