Response: Estimating the Age of the Common Ancestor of Men from the ZFY Intron     

Dorit RL  Akashi H  Gilbert W 《Science (New York, N.Y.)》1996,272(5266):1361-1362

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Lesion-induced sprouting in the rat dentate gyrus is inhibited by repeated ethanol administration     

West JR  Lind MD  Demuth RM  Parker ES  Alkana RL  Cassell M  Black AC 《Science (New York, N.Y.)》1982,218(4574):808-810

The effect of ethanol on hippocampal axonal sprouiting was studied with a histochemical technique for identifying acetylcholinesterase. Unilateral lesion of the entorhinal cortex in adult rats produced an increase in the density of acetylcho-linesterase staining in the outer molecular layer and a concomitant increase in the width of the pale-staining commissural-associational zone of the dentate gyrus. Other rats were given ethanol (11.3 +/- 0.45 grams per kilogram) for 2 weeks before and 9 days after receiving the lesion. Ethanol abolished the expansion of the commissural-associational zone. The effect of ethanol on sprouting axons suggests that it may inhibit recovery of function after brain injury.  相似文献   

Magnetic observations in studies of sea-floor spreading     

Kellogg WC  Larson RL  Spiess FN 《Science (New York, N.Y.)》1969,165(3893):617-618

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Global mapping of the yeast genetic interaction network   总被引：1，自引：0，他引：1  

Tong AH  Lesage G  Bader GD  Ding H  Xu H  Xin X  Young J  Berriz GF  Brost RL  Chang M  Chen Y  Cheng X  Chua G  Friesen H  Goldberg DS  Haynes J  Humphries C  He G  Hussein S  Ke L  Krogan N  Li Z  Levinson JN  Lu H  Ménard P  Munyana C  Parsons AB  Ryan O  Tonikian R  Roberts T  Sdicu AM  Shapiro J  Sheikh B  Suter B  Wong SL  Zhang LV  Zhu H  Burd CG  Munro S  Sander C  Rine J  Greenblatt J  Peter M  Bretscher A  Bell G  Roth FP  Brown GW  Andrews B  Bussey H  Boone C 《Science (New York, N.Y.)》2004,303(5659):808-813

A genetic interaction network containing approximately 1000 genes and approximately 4000 interactions was mapped by crossing mutations in 132 different query genes into a set of approximately 4700 viable gene yeast deletion mutants and scoring the double mutant progeny for fitness defects. Network connectivity was predictive of function because interactions often occurred among functionally related genes, and similar patterns of interactions tended to identify components of the same pathway. The genetic network exhibited dense local neighborhoods; therefore, the position of a gene on a partially mapped network is predictive of other genetic interactions. Because digenic interactions are common in yeast, similar networks may underlie the complex genetics associated with inherited phenotypes in other organisms.  相似文献   

Spin-dependent tunneling in self-assembled cobalt-nanocrystal superlattices     

Black CT  Murray CB  Sandstrom RL  Sun S 《Science (New York, N.Y.)》2000,290(5494):1131-1134

Self-assembled devices composed of periodic arrays of 10-nanometer-diameter cobalt nanocrystals display spin-dependent electron transport. Current-voltage characteristics are well described by single-electron tunneling in a uniform array. At temperatures below 20 kelvin, device magnetoresistance ratios are on the order of 10%, approaching the maximum predicted for ensembles of cobalt islands with randomly oriented preferred magnetic axes. Low-energy spin-flip scattering suppresses magnetoresistance with increasing temperature and bias-voltage.  相似文献   

MESSENGER observations of transient bursts of energetic electrons in Mercury's magnetosphere     

Ho GC  Krimigis SM  Gold RE  Baker DN  Slavin JA  Anderson BJ  Korth H  Starr RD  Lawrence DJ  McNutt RL  Solomon SC 《Science (New York, N.Y.)》2011,333(6051):1865-1868

The MESSENGER spacecraft began detecting energetic electrons with energies greater than 30 kilo-electron volts (keV) shortly after its insertion into orbit about Mercury. In contrast, no energetic protons were observed. The energetic electrons arrive as bursts lasting from seconds to hours and are most intense close to the planet, distributed in latitude from the equator to the north pole, and present at most local times. Energies can exceed 200 keV but often exhibit cutoffs near 100 keV. Angular distributions of the electrons about the magnetic field suggest that they do not execute complete drift paths around the planet. This set of characteristics demonstrates that Mercury's weak magnetic field does not support Van Allen-type radiation belts, unlike all other planets in the solar system with internal magnetic fields.  相似文献   

The global magnetic field of Mercury from MESSENGER orbital observations     

Anderson BJ  Johnson CL  Korth H  Purucker ME  Winslow RM  Slavin JA  Solomon SC  McNutt RL  Raines JM  Zurbuchen TH 《Science (New York, N.Y.)》2011,333(6051):1859-1862

Magnetometer data acquired by the MESSENGER spacecraft in orbit about Mercury permit the separation of internal and external magnetic field contributions. The global planetary field is represented as a southward-directed, spin-aligned, offset dipole centered on the spin axis. Positions where the cylindrical radial magnetic field component vanishes were used to map the magnetic equator and reveal an offset of 484 ± 11 kilometers northward of the geographic equator. The magnetic axis is tilted by less than 3° from the rotation axis. A magnetopause and tail-current model was defined by using 332 magnetopause crossing locations. Residuals of the net external and offset-dipole fields from observations north of 30°N yield a best-fit planetary moment of 195 ± 10 nanotesla-R(M)(3), where R(M) is Mercury's mean radius.  相似文献   

MESSENGER observations of the spatial distribution of planetary ions near Mercury     

Zurbuchen TH  Raines JM  Slavin JA  Gershman DJ  Gilbert JA  Gloeckler G  Anderson BJ  Baker DN  Korth H  Krimigis SM  Sarantos M  Schriver D  McNutt RL  Solomon SC 《Science (New York, N.Y.)》2011,333(6051):1862-1865

Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.  相似文献   

Preliminary Announcement of the New York Meeting and Call for Papers by AAAS Sections     

Taylor RL 《Science (New York, N.Y.)》1960,131(3413):1616-1622

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Materials: tribology experiment in zero gravity     

Pan CH  Gause RL  Whitaker AF 《Science (New York, N.Y.)》1984,225(4658):202-203

A tribology experiment in zero gravity was performed during the orbital flight of Spacelab 1 to study the motion of liquid lubricants over solid surfaces. The absence of a significant gravitational force facilitates studies of the motion of liquid lubricants over solid surfaces as controlled by interfacial and capillary forces. Observations were made of phenomena associated with the liquid on one solid surface and also with the liquid between a pair of closely spaced surfaces. Typical photographic records obtained on Spacelab 1 are described.  相似文献