A principal curve (Hastie and Stuetzle, 1989) is a smooth curve passing through the middle of a distribution or data cloud, and is a generalization of linear principal components. We give an alternative definition of a principal curve, based on a mixture model. Estimation is carried out through an EM algorithm. Some comparisons are made to the Hastie-Stuetzle definition. 相似文献
Nathan Glazer Ethnic Dilemmas Harvard, Harvard University Press. 1985
Giddens, Anthony The Constitution of Society, Berkeley, University of California, 1985, pp.XXXVII, 402. Notes, glossary, diagrams, bibliographic notes and index.
Jeremy Rifkin Declaration of a Heretic. Boston. London, Melbourne and Henley, Routledge and Kegan Paul, 1985, pp.X,140.
Ted Benton The Rise and Fall of Structural Marxism: Althusser and his Influence, New York, St.Martin's Press, 1984, pp. VII,259.
Raymond L. Garthoff Détente and Confrontation Washington, The Brookings Institution, 1985, pp.XVI,1126.
Joseph J. Collins The Soviet Invasion of Afghanistan. A Study in the Use of Force in Soviet Foreign Policy, Massachusetts/Toronto, D.C. Heath and Company/Lexington, 1986, pp. XV, 195.
Jan Shipps Mormonism: The Story of a New Religious Tradition, Chicago, University of Illinois Press, 1985, pp.211.
Robert Jay Lifton Home from the War: Vietnam Veterans: Neither Victims nor Executioners, New York, Basic Books, 1985, pp.478 相似文献
Recent interest has focused on the high school dropout rate as one indicator of the national education picture. Empirical estimates of this "rate" vary considerably, because these estimates are poorly defined. This article reviews some of the current measures and presents a new measure of the high school dropout rate--the proportion of high school students who drop out in a defined period of time (1 year). The estimates show that the national yearly high school dropout rate was about the same in 1985 as it was in 1968. Improvement has occurred, however, since 1968 for specific racial groups as well as for some grade levels. 相似文献
The phrase, the counterfinality of the practico-inert is from Sartre with reference to implications of modern technology as a shorthand for that enormous properly human and anti-natural power of dead human labor stored up in our machinery — an alienated power, which turns back on and against us in unrecognizable forms and can symbolize the massive dystopian horizon of organized crime as well as individual terrorist praxis (Jean-Paul Sartre (1948).Situations II. Paris: Gallimard). 相似文献
This paper describes a model which relates fertility to partner availability, an aspect of relative cohort size. Partner availability is affected by the tendency for males to reproduce at a later age than females. For women born at a time of rising birth rates, there is a shortage of slightly older men as potential partners. Women born when birthrates are falling enjoy a surplus of older men from which to choose. This model is believed to be the first non-linear demographic feedback model involving feedbacks through marriage squeezes in which empirically estimated values of the parameters imply persistent limit cycles. The deterministic model makes births in each five-year period a function of births in previous five-year periods. The form of the function is chosen to model the effect of partner availability upon entry into reproductive relationships, and therefore on age-specific fertility. Marriage rates are not modeled directly. The model was developed from data for more than a century from England and Wales, New Zealand, and the US. The demographic transition is modeled with a logistic function and age-specific fertility rates are estimated using lognormal distributions. The stepwise inclusion of a partner availability estimate in the model showed that it accounts for 29% of otherwise unexplained variance. Projected future births stabilize in sustained or limit cycles with periods a little longer than 40 years, and amplitudes of at least 7% of the mean. The necessary conditions for cycle persistence are outlined on a graph of maximum and minimum fertility parameters. 相似文献
This article explores the extent to which a decision maker's probabilities can be measured separately from his/her utilities by observing his/her acceptance of small monetary gambles. Only a partial separation is achieved: the acceptable gambles are partitioned into a set of belief gambles, which reveals probabilities distorted by marginal utilities for money, and a set of preference gambles, which reveals utilities reciprocally distorted by marginal utilities for money. However, the information in these gambles still enables us to solve the decision maker's problem: his/her utility-maximizing decision is the one that avoids arbitrage (i.e., incoherence or Dutch books). 相似文献
This study assessed the test–retest reliability and convergent validity of single items from the Assessment and Action Record (AAR), from Looking After Children (Ward, 1995). It also compared developmental outcomes of 43 children cared for by a Canadian child welfare agency and those of an approximate comparison group of 1,600 children from the National Longitudinal Survey of Children and Youth (Statistics Canada, 1995). High and low reliability and validity were found for different AAR items. The children in care had worse outcomes than the comparison children on indicators of educational success and negative behaviour, but not on measures of identity, social and family relationships, or prosocial behaviour. 相似文献
This paper argues that, since the Second Vatican Council (Vatican II), there has been a significant shift in the rhetorical stance of the Roman Catholic Church toward homosexuality in which the pre-council rhetoric, which condemned both act (i.e., homosexual behavior) and actor (i.e., the homosexual) has been replaced by two distinctly different rhetorics: a moral rhetoric, which continues the Church's long-standing condemnation of homosexual acts as sins, and a pastoral rhetoric, which argues that homosexuals should be ministered to and embraced. A Burkean pentadic analysis is used to define how the two rhetorics differ from each other and from the earlier rhetoric. The three major influences (i.e., Scripture, Tradition, and Catholic theology/philosophy) that have shaped, and continue to shape, the Church's position regarding homosexuality are described. Some of the socio-political implications of this shift are emphasized.相似文献
In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit's performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator's deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures. 相似文献