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71.
Prof. Dr. J. H. Ahrens 《Computing》1989,41(1-2):163-166
In many algorithms for sampling from non-uniform distributions the logarithm of a uniform deviate must be compared with some test quantity. It is shown that all these comparisons can be done efficiently without calling a logarithm subprogram: two procedures for this task are presented and compared. 相似文献
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A specific radioimmunoassay for platelet-activating factor (PAF) sensitive in the range 10–1000 pg (0.02–2 pmoles) has been
developed. Detailed quantitative hapten inhibition studies showed specificity for the acetyl group at C-2 of PAF, a requirement
for the ether linkage at C-1 and some tolerance for substituents on the choline nitrogen. No significant cross-reactivity
was found with phosphatidylcholine and lysophosphatidylcholine or with lysoPAF.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, Tokyo, Japan, May 1989. 相似文献
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Soft sediments from the Detroit River were analyzed for the USEPA priority pollutants to generally characterize contaminant distribution. Forty-three were detected. Highest heavy metal concentrations were found in the Trenton Channel and immediately downstream of Grosse Ile. They ranged from an area mean (N = 2) of 0.19 mg/kg mercury to 338.7 mg/kg zinc (dry weight). Polynuclear aromatic hydrocarbons ranged from 0.1 mg/kg to 38.8 mg/kg (mean, N = 2) with the highest levels near Grosse Ile. PCBs ranged from 0.015 mg/kg to 1.7 mg/kg (mean, N = 2). Organochlorine pesticides were not detected except for a trace of heptachlor in one sample. Sediment contamination in the Detroit River is widespread with higher concentrations on the U.S. side downstream of the Rouge River and in the Trenton Channel. The significance of these in-place pollutants to biota and as a source to Lake Erie is still unknown. 相似文献
76.
Summary Plastic yielding of anisotropic metals can be either described by a macroscopic constitutive relation or assessed by means of a model which correlates single and polycrystal behaviors. The mathematical identification of the plastic work rate derived from the two approaches, for all strain rate tensors, leads to a fit of the polycrystal yield surface by an analytical function. When a quadratic from is assumed, the macroscopic anisotropy parameters become explicit functions of the texture coefficients. This identification method is applied to calculate yield surfaces andR-values of rolled and annealed steel sheets: theR-values and in general the flow rule, are more significantly modified by the fitting than the yield surface. Thus, it is worth extending the method to more general constitutive relations which may be given by the form of their work function: alternative forms of the work function for plastic materials are explored, especially in the bearing of convexity and homogeneity where quadratic forms have a distinct advantage. Finally, it is shown that the identification of the work function allows to express the phenomenological coefficients as analytical functions of the texture parameters for many forms of the work function; in the other cases, these coefficients may be obtained by linear or non-linear regression. 相似文献
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Reinisch June M.; Sanders Stephanie A.; Ziemba-Davis Mary 《Canadian Metallurgical Quarterly》1988,43(11):921
To create the behavior-change programs essential for limiting the acquired immune deficiency syndrome (AIDS) epidemic, we must obtain a precise understanding of the sexual behavior, knowledge, and attitudes of our nation's various ethnic, racial, social, age, regional, and sexual orientation groups. Such information is necessary for developing the precisely targeted educational programs that currently are our most effective means of reducing risk behaviors and halting the spread of the disease in the United States. These behavioral data are also crucial to biomedical investigations, making possible the identification of appropriate subjects for programs ranging from the testing of vaccines to the evaluation of the threat to pregnant women and their offspring. In this article, we summarize data on sexual behaviors associated with the transmission of the AIDS virus (i.e., human immunodeficiency virus [HIV]) and discuss selected issues relevant to the conduct of research on human sexuality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献