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21.
C Andrew Clayton Larry Michael Edo D Pellizzari James J Quackenboss 《Quality Assurance: Good Practice, Regulation, and Law》2003,10(3-4):161-175
Multimedia data from two probability-based exposure studies were investigated in terms of how missing data and measurement-error imprecision affected estimation of population parameters and associations. Missing data resulted mainly from individuals'refusing to participate in certain measurement activities, rather than from field or laboratory problems; it suggests that future studies should focus on methods for maximizing participation rates. Measurement error variances computed from duplicate-sample data were small relative to the inherent variation in the populations; consequently, adjustments in nonparametric percentile estimates to account for measurement imprecision were small. Methods of adjustment based on lognormality assumptions, however, appeared to perform poorly. 相似文献
22.
Unicode is rapidly becoming the preferred means for representing symbols used in creating multimedia content, especially for information that's presented in multiple languages. This article discusses a unicode vulnerability that makes such content susceptible to being used for creation of covert channel communications. We also developed a solution architecture, the unified secure message augmentation (USMA) service. The USMA service incorporates rules (in an XML vocabulary) that we can apply to unicode transmissions that will detect an attempt to transmit a potential exploit, alert network managers to the presence of the unicode anomaly, and take action to mitigate the exploit. 相似文献
23.
Surveyed the prevalence of weight reducing and weight gaining in 1,373 high school students. 63% of the girls and 16.2% of the boys reported being on weight-reducing regimens; 9.1% of the girls and 28.4% of the boys were trying to gain weight. Most female reducers and male gainers were already normal weight. Whites and Hispanics were more likely to be reducing, whereas Blacks were more likely to be gaining. Exercise and moderate caloric reduction were most popular for weight reducing, and a small but significant number were regularly using fasting, vomiting, laxatives, and appetite suppressants. The rate of weight reducing in female high school adolescents has increased significantly since similar surveys of American youths 20 yrs ago. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
24.
Anirban Chakraborty James C. Earthman 《Metallurgical and Materials Transactions A》1997,28(4):979-989
Finite element simulations of the high-temperature behavior of single-phase γ, dual-phase α2+γ, and fully lamellar (FL) α2+γTiAl intermetallic alloy microstructures have been performed. Nonlinear viscous primary creep deformation is modeled in
each phase based on published creep data. Models were also developed that incorporate grain boundary and lath boundary sliding
in addition to the dislocation creep flow within each phase. Overall strain rates are compared to gain an understanding of
the relative influence each of these localized deformation mechanisms has on the creep strength of the microstructures considered.
Facet stress enhancement factors were also determined for the transverse grain facets in each model to examine the relative
susceptibility to creep damage. The results indicate that a mechanism for unrestricted sliding of γ lath boundaries theorized
by Hazzledine and co-workers leads to unrealistically high strain rates. However, the results also suggest that the greater
creep strength observed experimentally for the lamellar microstructure is primarily due to inhibited former grain boundary
sliding (GBS) in this microstructure compared to relatively unimpeded GBS in the equiaxed microstructures. The serrated nature
of the former grain boundaries generally observed for lamellar TiAl alloys is consistent with this finding. 相似文献
25.
O Hanisch CA Cortella MM Boskovic RA James J Slots UM Wikesj? 《Canadian Metallurgical Quarterly》1997,68(1):59-66
Factor V Leiden mutation was initially detected in thrombophilic patients and relatives by PCR RFLP (Restriction Fragment Length Polymorphism) according to Bertina (1). This technique presents some drawbacks and the current trend is to simplify the diagnosis. We describe a technique of Allele Specific Amplification (ASA) which is optimized in terms of reliability: an additional mismatch in antepenultimate position enables to obtain the same specificity as PCR RFLP. Furthermore, coamplification of internal control warrants an optimal sensitivity. All the PCR have been simplified: the DNA extraction improvement allows to analyse the genotype with only a few microliters of whole blood whatever the anticoagulant and the procedure of preservation (freezing, dried blood spots, storage at +4 degrees C for several days). This technique saves time. Moreover, full automation of the ASA technique may be shortened thanks to the lack of extraction and the positive/negative reading of the PCR signal. 相似文献
26.
James A. Ward 《Information Systems Management》1997,14(1):62-65
The road to employee empowerment runs between true commitment on the one side and enforced compliance and chaos on the other. By following this column's guidelines, IS managers can steer their organizations to success and help free employees to be more creative in terms of both quality and productivity. 相似文献
27.
Sir James Lighthill 《Journal of Engineering Mathematics》1996,30(1-2):35-78
Helical distributions of stokeslets can valuably model microbial locomotion through a fluid, and also the flow field generated, wherever a flagellum actively executes helical undulations (as in many single-celled algae and protozoa) or where (as in many bacteria) the action of rotary motors causes a passive structure of helical shape (which may be a flagellum or else the cell body itself) to rotate. Here, previous biomechanical studies of such modes of locomotion are extended to include analyses of three-dimensional flow fields. In some cases, a rotlet field (curl of a stokeslet) needs to be incorporated in the models. For example, spirochete swimming is modelled by combined helical distributions of stokeslets and rotlets; the computed flow field being confined to within distances of less than twice the radius of the cell body's helical shape from its axis, while including a powerful jet-like interior flow through the coils of the swimming spirochete. 相似文献
28.
James Lighthill 《Journal of Engineering Mathematics》1996,30(1-2):25-34
Lorentz [1] pioneered the representation of flows at very low Reynolds number by a surface distribution of stokeslets — whose strengths, nowadays, are computed by surface-velocity collocations. That method is here compared with a representation widely used in flagellar hydrodynamics, by a curvilinear distribution of stokeslets and dipoles along the flagellar centreline; with the velocity of each cross-section expressed as a centreline value of the combined fields of singularities beyond a certain cutoff distance. The latter is also a good representation, and offers moreover some computational advantages. This paper establishes the equivalence of the two representations, and identifies those properties of Stokes flows which make both the dipoles and the cutoff essential to that equivalence. 相似文献
29.
Treatment of the addictions is changing. Psychosocial treatment programs and research projects have changed the way helping professionals view, treat, and prevent drug abuse. This article reviews the contributions included in this special series; they encompass several general issues facing psychologists who conduct treatment, research, and teaching in the field of addictive behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
30.
Abstract: Environmental justice advocates have recently focused attention on cumulative exposure in minority neighborhoods due to multiple sources of pollution. This article uses U.S. EPA's National Air Toxics Assessment (NATA) for 1996 to examine environmental inequality in California, a state that has been a recent innovator in environmental justice policy. We first estimate potential lifetime cancer risks from mobile and stationary sources. We then consider the distribution of these risks using both simple comparisons and a multivariate model in which we control for income, land use, and other explanatory factors, as well as spatial correlation. We find large racial disparities in California's “riskscape” as well as inequalities by other factors and suggest several implications for environmental and land use policy. 相似文献