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991.
992.
This paper studies the topological approach to social choice theory initiated by G. Chichilnisky (1980), extending it to
the case of a continuum of agents. The social choice rules are continuous anonymous maps defined on preference spaces which
respect unanimity. We establish that a social choice rule exists for a continuum of agents if and only if the space of preferences is contractible. We provide also a topological characterization of such
rules as generalized means or mathematical expectations of individual preferences.
Received: 30 November 1994/Accepted: 22 April 1996 相似文献
993.
994.
Interest organizations are hypothesized to strongly affect public policy, but the evidence that they do so is mixed. This article argues that one reason for the disparity is a gap between theory and research: theory suggests that information provided by interest organizations should strongly influence elected officials, but there is no systematic research on its impact. We examine a potentially important source of information for members of the U.S. Congress—testimony at committee hearings—to ascertain if it affects the enactment of policy proposals. The data, based on content analysis of almost 1,000 testimonies on a stratified random sample of policy proposals, describe who testifies, their arguments, and the evidence they provide. Supporters of a proposal emphasize the importance of the problem being addressed, while opponents claim the proposed policy will be ineffective and try to reframe the debate. Information—particularly information regarding policy effectiveness—does affect the likelihood that a policy proposal will be enacted. 相似文献
995.
SUMMARY. Three one day workshops for 40 senior clinical staff were held to introduce a new Operational Policy on Child Sexual Abuse (CSA) and to provide them with a teaching package to enable them to run ‘cascade’ teaching sessions for other staff and colleagues. Part I of this paper describes an evaluation of the workshop; Part II describes an evaluation of the cascade The workshop evaluation showed that knowledge about CSA and policy issues was already good, but although that knowledge did improve after the workshop, attitudes about sexual behaviour were not changed by the workshop. Evaluation of the cascade also showed an increase in knowledge after the dissemination exercise 相似文献
996.
We describe the application of tools from statistical mechanics to analyse the dynamics of various classes of supervised learning rules in perceptrons. The character of this paper is mostly that of a cross between a biased non-encyclopaedic review and lecture notes: we try to present a coherent and self-contained picture of the basics of this field, to explain the ideas and tricks, to show how the predictions of the theory compare with (simulation) experiments, and to bring together scattered results. Technical details are given explicitly in an appendix. In order to avoid distraction we concentrate the references in a final section. In addition this paper contains some new results: (i) explicit solutions of the macroscopic equations that describe the error evolution for on-line and batch learning rules; (ii) an analysis of the dynamics of arbitrary macroscopic observables (for complete and incomplete training sets), leading to a general Fokker–Planck equation; and (iii) the macroscopic laws describing batch learning with complete training sets. We close the paper with a preliminary expose´ of ongoing research on the dynamics of learning for the case where the training set is incomplete (i.e. where the number of examples scales linearly with the network size). 相似文献
997.
Using data from the British Household Panel Survey and the National Survey of Families and Households in the United States, we present a sociodemographic profile of fathers and compare the determinants of absent fatherhood in each country. Although fatherhood has a younger profile in the United States, especially for blacks, predictors of fathers’ residency with their children are remarkably similar in the two countries. In both countries, the strongest predictor of a father’s absence is the parents’ relationship to each other at the time of the child’s birth. Policy implications of this finding are discussed. 相似文献
998.
Contemporary rural social movements bring diverse interest groups and stakeholders together at the local scale in the pursuit of common visions and goals, often against the backdrop of an external threat. The challenge for a movement's leaders is to negotiate and design a rural agenda that resonates with this complex constituency. One way to approach this problem is to construct and politicize a local sense of place as a means of rallying insiders against outside forces and pressures. This article explores the place-making activities of rural leaders operating within a complex social setting through an analysis of a grassroots social movement in Anahim Lake, British Columbia. The study uses the concept of the “place frame” to explore how Anahim's activists created a local discursive framework that enabled them to bridge dissimilar environmental values and practices within the community. The removal of external pressures following protest, however, saw the dissolution of this alignment. In documenting this process, the article contributes to a fuller understanding of the significance of place in grassroots protest and activism. 相似文献
999.
1000.
A. K. S. Alshabani I. L. Dryden C. D. Litton J. Richardson 《Journal of the Royal Statistical Society. Series C, Applied statistics》2007,56(4):415-428
Summary. We consider the Bayesian analysis of human movement data, where the subjects perform various reaching tasks. A set of markers is placed on each subject and a system of cameras records the three-dimensional Cartesian co-ordinates of the markers during the reaching movement. It is of interest to describe the mean and variability of the curves that are traced by the markers during one reaching movement, and to identify any differences due to covariates. We propose a methodology based on a hierarchical Bayesian model for the curves. An important part of the method is to obtain identifiable features of the movement so that different curves can be compared after temporal warping. We consider four landmarks and a set of equally spaced pseudolandmarks are located in between. We demonstrate that the algorithm works well in locating the landmarks, and shape analysis techniques are used to describe the posterior distribution of the mean curve. A feature of this type of data is that some parts of the movement data may be missing—the Bayesian methodology is easily adapted to cope with this situation. 相似文献