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21.
22.
对无理数e在电路分析中出现的几个典型例子作了分析讨论,明确指出:由1/e决定的特征常数可以在时间分布上和空间分布上,把一个按指数规律非均匀变化的问题,用一个等效的均匀变化的问题来表示;可以反映初始变化率与最终稳定值之间的联系;可以更深刻地反映某些物理过程的本质特征。 相似文献
23.
If a population contains many zero values and the sample size is not very large, the traditional normal approximation‐based confidence intervals for the population mean may have poor coverage probabilities. This problem is substantially reduced by constructing parametric likelihood ratio intervals when an appropriate mixture model can be found. In the context of survey sampling, however, there is a general preference for making minimal assumptions about the population under study. The authors have therefore investigated the coverage properties of nonparametric empirical likelihood confidence intervals for the population mean. They show that under a variety of hypothetical populations, these intervals often outperformed parametric likelihood intervals by having more balanced coverage rates and larger lower bounds. The authors illustrate their methodology using data from the Canadian Labour Force Survey for the year 2000. 相似文献
24.
Conservation biology aims at assessing the status of a population, based on information which is often incomplete. Integrated population modelling based on state‐space models appears to be a powerful and relevant way of combining into a single likelihood several types of information such as capture‐recapture data and population surveys. In this paper, the authors describe the principles of integrated population modelling and they evaluate its performance for conservation biology based on a case study, that of the black‐footed albatross, a northern Pacific albatross species suspected to be impacted by longline fishing 相似文献
25.
Tracey Maegusuku‐Hewett David Dunkerley Jonathan Scourfield Nina Smalley 《Children & Society》2007,21(4):309-321
This article aims to makes a contribution to redressing a methodological and theoretical imbalance in existing research on refugee and asylum‐seeking children. It draws on two qualitative studies from Wales with children and young people. The samples include unaccompanied minors and children living with families as well as both children who are supported in the asylum system and those who have been granted refugee status. The focus on ecological post‐migratory stressors and coping processes that young people identify as being integral to their well‐being and, once granted status, to how they adapt to settlement includes a selective study of some of the sources of resilience referred to in the children's talk. Recognising the interplay between individual and environment leads to a discussion of both personal attributes and collective cultural identities. 相似文献
26.
James R. Vanderwoerd 《Nonprofit management & leadership》2004,14(3):239-262
This article reports selected findings from a qualitative case study of two faith‐based social service organizations to address two questions: (1) How does government funding influence the religious characteristics of faith‐based social service organizations? (2) How do government‐funded, faith‐based social service organizations manage the tensions arising from both secular and religious contexts? The findings suggest that the adaptation of secular institutional practices is not as inevitable as some have feared. Rather, the two organizations studied showed convincingly that their faith traditions and values were alive and widely evident throughout their organizations. Three key strategies emerged as means for maintaining religiousness in the face of secular pressures: (1) Religious identities were perceived as given rather than chosen, and therefore were not negotiable; (2) religious values provided strong justification for seeking relationships with others who do not share their faith; (3) the religious worldview blurred religious and secular distinctions so that secular technologies and practices could comfortably be utilized. 相似文献
27.
28.
We examine the labor-cost savings associated with privatization by comparing earnings and employment trends of public and
private sector refuse workers. Findings suggest that high union earnings for workers in the public sector are a source of
labor-cost savings in the refuse industry. Evidence on job changers does not indicate that earnings for this group of workers
are a compensating differential. Metropolitan area employment findings suggest that municipalities are less likely to use
union refuse workers in the public sector when a relatively small percentage of area residents belong to a union.
The authors thank Jacqueline Agesa, Keith Bender, Maria Crawford, and Richard Perlman for valuable suggestions. Research assistance
from Eric Blackburn is greatly appreciated. 相似文献
29.
30.
Emmanuelle Cam Bernard Cadiou James E. Hines Jean Yves Monnat 《Journal of applied statistics》2002,29(1):163-185
Many studies have provided evidence that, in birds, inexperienced breeders have a lower probability of breeding successfully. This is often explained by lack of skills and knowledge, and sometimes late laying dates in the first breeding attempt. There is growing evidence that in many species with deferred reproduction, some prebreeders attend breeding places, acquire territories and form pairs. Several behavioural tactics assumed to be associated with territory acquisition have been described in different species. These tactics may influence the probability of recruiting in the breeding segment of the population, age of first breeding, and reproductive success in the first breeding attempt. Here we addressed the influence of behaviour ('squatting') during the prebreeding period on demographic parameters (survival and recruitment probability) in a long-lived colonial seabird species: the kittiwake. We also investigated the influence of behaviour on reproductive trajectory. Squatters have a higher survival and recruitment probability, and a higher probability of breeding successfully in the first breeding attempt in all age-classes where this category is represented. The influence of behaviour is mainly expressed in the first reproduction. However, there is a relationship between breeding success in the first occasion and subsequent occasions. The influence of breeding success in the first breeding attempt on the rest of the trajectory may indirectly reflect the influence of behaviour on breeding success in the first occasion. The shape of the reproductive trajectory is influenced by behaviour and age of first breeding. There is substantial individual variation from the mean reproductive trajectory, which is accounted for by heterogeneity in performance among individuals in the first attempt, but there is no evidence of individual heterogeneity in the rate of change over time in performance in subsequent breeding occasions 相似文献