Species Abundance: Natural Regulation of Insular Variation     

Hamilton TH  Rubinoff I  Barth RH  Bush GL 《Science (New York, N.Y.)》1963,142(3599):1575-1577

Variation in numbers of land plant species on islands in the Galapagos Archipelago can be predicted on the basis of elevation, area of the adjacent island, distance from the nearest island, and distance from the center of the archipelago, but not on the basis of the area of the host island. Multiple linear regression (y = bx(1) + bx(2) . . .) gives better "goodness of fit" than curvilinear analysis (y = bx(z)). The variation in number of species on large islands can be predicted more accurately than the variation on small ones. Ecologic diversity and isolation are the natural regulators of species abundance.  相似文献   

Distribution of uranium in some natural minerals     

Hamilton EI 《Science (New York, N.Y.)》1966,151(3710):570-572

The advantages of the fission method over conventional autoradiography for studying the distribution of uranium in natural minerals is described. Relatively high concentrations of uranium associated with micro inclusions in the St. Marks enstatite chondrite have been observed and may account for the variation of the uranium concentrations in different samples of this meteorite.  相似文献   

Ad Hoc Team Revives SSC Competition     

Hamilton DP 《Science (New York, N.Y.)》1991,252(5013):1610

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Skeptics pour cold water on a Russian ;fire sale'     

Hamilton DP 《Science (New York, N.Y.)》1992,256(5063):1510-1511

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In reply: magnetic fusion     

Hamilton DP 《Science (New York, N.Y.)》1990,250(4979):359

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Radiant solar energy and the function of black homeotherm pigmentation: an hypothesis     

W J Hamilton  F Heppner 《Science (New York, N.Y.)》1967,155(759):196-197

White zebra finches exposed to artificial sunlight used an average of 22.9 percent less energy after they were dyed black. The hypothesis that black homeotherm coloration functions primarily to maximize absorption of radiant solar energy is suggested. This hypothesis may explain the dark skin pigmentation of certain human populations.  相似文献   

Geometry of the Perxenate Ion     

Hamilton WC  Ibers JA  Mackenzie DR 《Science (New York, N.Y.)》1963,141(3580):532-534

A three-dimensional x-ray analylsis of a crystallinie solid of Xe(+8) formed by the reaction of XeF(6) with sodium hydroxide solution indicates that it is sodium perxenate octahydrate, Na(4)XeO(6) * 8H(2)O. The perxenate ion, XeO(6)(-4), has approximately a regular octahedral configuration with a mean xenon-oxygen bond length of 1.875 A.  相似文献   

Chromosome 17 deletions and p53 gene mutations in colorectal carcinomas   总被引：175，自引：0，他引：175  

S J Baker  E R Fearon  J M Nigro  S R Hamilton  A C Preisinger  J M Jessup  P vanTuinen  D H Ledbetter  D F Barker  Y Nakamura  R White  B Vogelstein 《Science (New York, N.Y.)》1989,244(4901):217-221

Previous studies have demonstrated that allelic deletions of the short arm of chromosome 17 occur in over 75% of colorectal carcinomas. Twenty chromosome 17p markers were used to localize the common region of deletion in these tumors to a region contained within bands 17p12 to 17p13.3. This region contains the gene for the transformation-associated protein p53. Southern and Northern blot hybridization experiments provided no evidence for gross alterations of the p53 gene or surrounding sequences. As a more rigorous test of the possibility that p53 was a target of the deletions, the p53 coding regions from two tumors were analyzed; these two tumors, like most colorectal carcinomas, had allelic deletions of chromosome 17p and expressed considerable amounts of p53 messenger RNA from the remaining allele. The remaining p53 allele was mutated in both tumors, with an alanine substituted for valine at codon 143 of one tumor and a histidine substituted for arginine at codon 175 of the second tumor. Both mutations occurred in a highly conserved region of the p53 gene that was previously found to be mutated in murine p53 oncogenes. The data suggest that p53 gene mutations may be involved in colorectal neoplasia, perhaps through inactivation of a tumor suppressor function of the wild-type p53 gene.  相似文献   

NASA Researchers Protest DOE Turnoff     

Hamilton DP 《Science (New York, N.Y.)》1992,256(5062):1388

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Coal conversion technologies: some health and environmental effects     

Morris SC  Moskowitz PD  Sevian WA  Silberstein S  Hamilton LD 《Science (New York, N.Y.)》1979,206(4419):654-662

Several technologies to convert coal to liquid and gaseous fuels are being developed in the United States, some with support from the Department of Energy. Substitution of these technologies for those currently being used will produce different health and environmental hazards. In this article, selected health and environmental effects of four coal conversion and four existing technologies are compared. For each technology, the emission estimates for complete fuel cycles, including all steps in fuel use from extraction to the end use of space and water heating by electricity or direct combustion, were prepared by means of the Brookhaven Energy System Network Simulator model. Quantitative occupational health and safety estimates are presented for the extraction, transportation, distribution, processing, and conversion activities associated with each technology; also included are some public health damage estimates arising from fuel transportation and air pollution impacts. Qualitative estimates of health damage due to polycyclic organic matter and reduced sulfur are discussed. In general, energy inefficiencies, environmental residuals, and hence implied environmental effects and health damage increase in the order: (i) direct combustion of natural gas and oil, (ii) direct combustion of synthetic gas and oil, (iii) central-station electric power produced from synthetic gas, (iv) central-station electric power produced from coal, and (v) central-station electric power produced by the combustion of synthetic liquid fuels. The compliance and conflict of these technologies with the amendments of the Clean Air Act and other legislation are discussed.  相似文献