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921.
The so-called “principal formulae” of planar integral geometry are conventionally couched in terms of the “kinematic density”dxdydθ. Here a corresponding theory with respect to the “Lebesgue density”dxdy, that is with rotations suppressed, is developed. The only real difference is that the new “fundamental formula of Blaschke”contains a term depending upon the relative orientations of the two domains involved. In particular, the remarkable iteration property of these formulae carries over. The usual principal formulae follow as a corollary of the formulae given here, upon, averaging over orientations.  相似文献   
922.
923.
An attempt is made to establish primary integration as a major variable in explaining citizen involvement in political life. It is argued that a convincing case requires a demonstration that the variable is both empirically important and theoretically meaningful. The former is examined through data from a sample survey of an English city. Theoretical meaning is established through focussing upon the idea of sociable talk as a key factor in reality construction, including the construction of political events as a proximate world available for the interest and participation by the individual.  相似文献   
924.
Evidence suggests that African American youths initiate sexual activity at earlier ages than do European American or Latino youths. Using data from a multilevel study in Chicago, we developed and tested a neighborhood-based model of the timing of first adolescent intercourse that emphasizes the impact of neighborhood structural disadvantage and collective efficacy on early sexual activity (at ages 11 to 16). In turn, we explored the extent to which neighborhood factors account for racial differences in the timing of first intercourse. The findings indicate that demographic background, family processes, peer influences, and developmental risk factors account for about 30% of the baseline increased likelihood of early sexual onset for African American youths compared with European American youths. However, a significant residual racial difference remained even after we considered a host of micro-level factors. Neighborhood-level concentrated poverty largely explained this residual racial difference. Collective efficacy also independently contributed to the delay of sexual onset. No significant baseline difference in age of sexual initiation was found between Latino and European American youths.  相似文献   
925.
Support provided by family and friends may influence the extent to which older women who are primary caregivers for a spouse with dementia adhere to an exercise routine. The current study reports on qualitative interviews with 30 older female caregivers taking part in an exercise intervention regarding the support they received for their exercise goals. Results indicate that nearly all women received some level of verbal encouragement from family and friends, though far fewer had exercise partners or someone to stay with their husbands while they exercised. To reflect the wide variation observed in the amount of exercise support received and needed by caregivers, a typology of support situations was constructed as follows: Self-reliant, Well-supported, Under-supported, and Superfluous support. Implications for future exercise interventions targeting this population are discussed.  相似文献   
926.
How do family arrangements affect subjective well-being? We investigate this issue using data pooled from the IsssA and HILDA, both large, representative national samples of Australia (pooled n=38 447). Our regression analysis of cross-sectional and panel data examines how large are the differences in life satisfaction according to marital status and cohabitation. We find that women and men in formal marriages experience higher levels of life satisfaction than do people in other family arrangements. Moreover, both multiple tests in the cross-section, and tests controlling for prior happiness in the panel analysis, suggest that this is a causal relationship. Aggregating up the levels of life satisfaction generated by different marriage and cohabitation arrangements across a lifetime, suggests that a life-long marriage is the most satisfying. Early divorce followed by an enduring second marriage is little worse (because little time is spent outside the married state). But divorce without remarriage, or long lasting cohabitation without formal marriage, reduce the lifetime sum of subjective well-being by 4–12% for both women and men.  相似文献   
927.
Has the relative unemployment propensity for the low-skilled increased during the 1990s? We address this question empirically, based on two notions of low skills; i) low education, and ii) low ability, conditioned on education and work experience. Ability is identified by previous earnings. Evaluated by the education-based measure, we find that unemployment propensity has not developed unfavourably for the low-skilled. Evaluated by the ability-based measure, it has. We uncover a steady deterioration of employment prospects for persons with low ability relative to others with similar formal qualifications. The adverse employment effects of being low-skilled are stronger the higher is formal education.All correspondence to Knut Røed. The paper is part of the project Sorting, exposed groups and labour market programs financed by the Research Council of Norway. We wish to thank Rolf Aaberge, Paul Gertler, Harald Goldstein, Karl Ove Moene, Jon Strand, Steinar Strøm, Asbjrn Rødseth and an anonymous referee for helpful comments. Responsible editor: John F. Ermisch.  相似文献   
928.
Interdependency analysis in the context of this article is a process of assessing and managing risks inherent in a system of interconnected entities (e.g., infrastructures or industry sectors). Invoking the principles of input-output (I-O) and decomposition analysis, the article offers a framework for describing how terrorism-induced perturbations can propagate due to interconnectedness. Data published by the Bureau of Economic Analysis Division of the U.S. Department of Commerce is utilized to present applications to serve as test beds for the proposed framework. Specifically, a case study estimating the economic impact of airline demand perturbations to national-level U.S. sectors is made possible using I-O matrices. A ranking of the affected sectors according to their vulnerability to perturbations originating from a primary sector (e.g., air transportation) can serve as important input to risk management. For example, limited resources can be prioritized for the "top-n" sectors that are perceived to suffer the greatest economic losses due to terrorism. In addition, regional decomposition via location quotients enables the analysis of local-level terrorism events. The Regional I-O Multiplier System II (RIMS II) Division of the U.S. Department of Commerce is the agency responsible for releasing the regional multipliers for various geographical resolutions (economic areas, states, and counties). A regional-level case study demonstrates a process of estimating the economic impact of transportation-related scenarios on industry sectors within Economic Area 010 (the New York metropolitan region and vicinities).  相似文献   
929.
This paper provides a new way of conceptualizing the career of the mentally ill. Most persons who experience an episode of a serious mental disturbance lead a normal life, while a few persons lead lifetimes that revolve around their mental disorders. The processes leading to either result can only be understood by integrating the traditional labeling and psychiatric perspectives with lay understandings of the concepts of "mental illness" and "nervous breakdowns." A selection of key concepts from these perspectives leads to a better understanding of the different paths persons take as they move through the pre-patient, inpatient, and post-patient phases of the "career of the mentally ill." This perspective makes understandable a number of counterintuitive relationships. For example, it explains why most hospitalized mental patients (1) have a negative stereotype of the "mentally ill," (2) do not perceive themselves as "mentally ill, yet (3) perceive themselves as benefiting from treatment, and (4) do not progress into a career of secondary deviance.  相似文献   
930.
Food insufficiency is a significant problem in the United States, and poor African American women with children are at especially high risk. An inadequate household food supply can potentially affect the well-being of household members, but it is difficult to distinguish the effects of food insufficiency from risk factors for poor health that are also common among the food insufficient, such as poverty. We examined food insufficiency and physical and mental health among African American and white women (n = 676) who were welfare recipients in 1997. Controlling for common risk factors, women who reported food insufficiency in both 1997 and 1998 were more likely to report fair or poor health at the later date. Food insufficiency in 1998 was significantly associated with meeting the diagnostic screening criteria for recent major depression. Food insufficiency at both times and in 1998 only was related to women's sense of mastery. These findings add to growing evidence that household food insufficiency is associated with poor physical and mental health.  相似文献   
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