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The consumer behaviour of the poor in the long eighteenth century has attracted more historical attention in recent years. Yet, we have little understanding of whether regional factors affected consumption or how the poor’s ownership of household goods was influenced by level of poverty and the life-cycle. By focusing on Kent and drawing comparisons to other counties, this article argues that the material lives of the poor were improving by the late eighteenth century, but finds that there were distinct regional differences as the poor acquired more and better goods in London and the Home Counties than in relatively remote areas. Moreover, by using pauper inventories and labourers’ probate inventories, the research finds that the poor were not a homogeneous group with similar levels of material wealth, but should be considered in terms of different subgroups which often led very different material lives to one another due to life-cycle-related problems including sickness and old age. Labourers’ probate inventories are found to represent a minority of the poor who were materially richer than most, whilst pauper inventories appear to represent a more typical subgroup of the poor that struggled to make do and owned most types of goods in smaller numbers.  相似文献   
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Service-learning programs are not free from challenges brought about by lack of financial support, lack of widespread commitment from professors, community agencies, and recipients of service, and lack of knowledge and insight in students directly involved in such programs. While service-learning initiatives and programs serve positive functions for organizations and individuals, rhetorical accolades for service learning can distort or omit the realities of program implementation and sustained delivery. This paper specifically explores the following challenges connected to service-learning programs: (1) pedagogical difficulties; (2) student limitations; (3) time constraints; and (4) community cooperation.  相似文献   
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Spatial variation in soil inorganic nitrogen across an arid urban ecosystem   总被引:4,自引:1,他引:3  
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.  相似文献   
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Summary.  Non-ignorable missing data, a serious problem in both clinical trials and observational studies, can lead to biased inferences. Quality-of-life measures have become increasingly popular in clinical trials. However, these measures are often incompletely observed, and investigators may suspect that missing quality-of-life data are likely to be non-ignorable. Although several recent references have addressed missing covariates in survival analysis, they all required the assumption that missingness is at random or that all covariates are discrete. We present a method for estimating the parameters in the Cox proportional hazards model when missing covariates may be non-ignorable and continuous or discrete. Our method is useful in reducing the bias and improving efficiency in the presence of missing data. The methodology clearly specifies assumptions about the missing data mechanism and, through sensitivity analysis, helps investigators to understand the potential effect of missing data on study results.  相似文献   
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Summary.  When evaluating potential interventions for cancer prevention, it is necessary to compare benefits and harms. With new study designs, new statistical approaches may be needed to facilitate this comparison. A case in point arose in a proposed genetic substudy of a randomized trial of tamoxifen versus placebo in asymptomatic women who were at high risk for breast cancer. Although the randomized trial showed that tamoxifen substantially reduced the risk of breast cancer, the harms from tamoxifen were serious and some were life threaten-ing. In hopes of finding a subset of women with inherited risk genes who derive greater bene-fits from tamoxifen, we proposed a nested case–control study to test some trial subjects for various genes and new statistical methods to extrapolate benefits and harms to the general population. An important design question is whether or not the study should target common low penetrance genes. Our calculations show that useful results are only likely with rare high penetrance genes.  相似文献   
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Book‐reviews     
World Commission on Environment and Development, Our Common Future. (The Brundtland Report). Oxford, Oxford University Pres, 1987. pp. XV + 387.  相似文献   
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