Speech parts as Poisson processes

This paper presents evidence that six of the seven parts of speech occur in written text as Poisson processes, simple or recurring. The six major parts are nouns, verbs, adjectives, adverbs, prepositions, and conjunctions, with the interjection occurring too infrequently to support a model. The data consist of more than the first 5000 words of works by four major authors coded to label the parts of speech, as well as periods (sentence terminators). Sentence length is measured via the period and found to be normally distributed with no stochastic model identified for its occurrence. The models for all six speech parts but the noun significantly distinguish some pairs of authors and likewise for the joint use of all words types. Any one author is significantly distinguished from any other by at least one word type and sentence length very significantly distinguishes each from all others. The variety of word type use, measured by Shannon entropy, builds to about 90% of its maximum possible value. The rate constants for nouns are close to the fractions of maximum entropy achieved. This finding together with the stochastic models and the relations among them suggest that the noun may be a primitive organizer of written text.     

MCMC estimation and some model-fit analysis of multidimensional IRT models

A Bayesian procedure to estimate the three-parameter normal ogive model and a generalization of the procedure to a model with multidimensional ability parameters are presented. The procedure is a generalization of a procedure by Albert (1992) for estimating the two-parameter normal ogive model. The procedure supports analyzing data from multiple populations and incomplete designs. It is shown that restrictions can be imposed on the factor matrix for testing specific hypotheses about the ability structure. The technique is illustrated using simulated and real data. The authors would like to thank Norman Verhelst for his valuable comments and ACT, CITO group and SweSAT for the use of their data.     

Rotation in the dynamic factor modeling of multivariate stationary time series

A special rotation procedure is proposed for the exploratory dynamic factor model for stationary multivariate time series. The rotation procedure applies separately to each univariate component series of aq-variate latent factor series and transforms such a component, initially represented as white noise, into a univariate moving-average. This is accomplished by minimizing a so-called state-space criterion that penalizes deviations of the rotated solution from a generalized state-space model with only instantaneous factor loadings. Alternative criteria are discussed in the closing section. The results of an empirical application are presented in some detail.This research was supported by the Institute for Developmental and Health Research Methodology, University of Virginia.     

Identifiability of nonlinear logistic test models

The linear logistic test model (LLTM) specifies the item parameters as a weighted sum of basic parameters. The LLTM is a special case of a more general nonlinear logistic test model (NLTM) where the weights are partially unknown. This paper is about the identifiability of the NLTM. Sufficient and necessary conditions for global identifiability are presented for a NLTM where the weights are linear functions, while conditions for local identifiability are shown to require a model with less restrictions. It is also discussed how these conditions are checked using an algorithm due to Bekker, Merckens, and Wansbeek (1994). Several illustrations are given.This article was written while the first author was a post doctoral fellow at the university of Twente. He gratefully acknowledges the university's hospitality and the financial support by NWO (project nr. 30002).     

A computational model of frontal lobe dysfunction: working memory and the Tower of Hanoi task

A symbolic computer model, employing the perceptual strategy, is presented for solving Tower of Hanoi problems. The model is calibrated—in terms of the number of problems solved, time taken, and number of moves made—to the performance of 20 normal subjects. It is then "lesioned" by increasing the decay rate of elements in working memory to model the performance of 20 patients with lesions to the prefrontal cortex. The model captures both the main effects of subject groups (patients and normal controls) performance, and the subject groups (patients and normal controls) by problem difficulty interactions. This leads us to support the working memory hypothesis of frontal lobe functions, but for a narrow range of problems.     

Scharffs' Application of Hopper's Concept: “Incohesion: Aggregation/Massification”

We begin by stating our understanding of the concepts presented in Hopper's paper, then comment on the clinical illustration, and conclude by describing two group situations in which we have applied the concepts we have taken from Hopper's paper. Hopper's fourth basic assumption applies to our work as individual psychoanalysts, family therapists, and group leaders because it integrates psychoanalytic and social understanding. We demonstrate how and why we find Hopper's idea to be a useful advance.     

The Possible Place of Cognitive Appraisal in the ABC Model Underlying Rational Emotive Behavior Therapy

In a critique of Ellis' Rational Emotive Behavior Therapy (REBT) theory of personality, it has been argued that, among other strategies, REBT personality theory could be significantly advanced by attempting to incorporate within it already established theoretical constructs compatible with the cognitive-behavioral movement. Richard Lazarus' prominent, well-articulated, and extensively studied theoretical construct of cognitive appraisal seems ideal in this regard. In the present article, the relevant and salient aspects of Lazarus' construct are described. An attempt is then made to delineate the possible place of cognitive appraisal in the ABC model underlying REBT. Finally, the clinical implications of this proposed ABC model refinement are then explored, and an additional REBT therapeutic strategy based upon the cognitive appraisal construct, reappraisal training, is suggested and briefly described.     

Mentoring: Some ethical considerations

To counter confusion about the term ‘mentor’, and address concerns about the scarcity of mentoring, I argue for an “honorific” definition, according to which a mentor is virtuous like a saint or hero. Given the unbounded commitment of mentors, mentoring relationships must be voluntary. In contrast, the role of advisor can be specified, mandated, and monitored. I argue that departments and research groups have a moral responsibility to devise a system of roles and structures to meet graduate students’ and postdoctoral fellows’ needs for information and advice. An earlier version of this paper was presented at a conference sponsored by the National Science Foundation on Mentoring and Research Values: Students as Vital Human Resources, Chicago, March 1995.     

Mentors, advisors and supervisors: Their role in teaching responsible research conduct

Although the terms mentor and thesis advisor (or research supervisor) are often used interchangeably, the responsibilities associated with these roles are distinct, even when they overlap. Neither are role models necessarily mentors, though mentors are role models: good examples are necessary but not sufficient. Mentorship is both a personal and a professional relationship. It has the potential for raising a number of ethical concerns, including issues of accuracy and reliability of the information conveyed, access, stereotyping and tracking of advisees, and the abuse of power. Nevertheless, mentors can be critically important for professional success and are one of a number of elements that affect the responsible conduct of research. In addition, the community as a whole has a responsibility to mentor junior members. An earlier version of this paper was presented at a conference sponsored by the National Science Foundation on Mentoring and Research Values: Students as Vital Human Resources, Chicago, USA, March 1995.     

建立新一代的精神分裂症动物模型

精神分裂症动物模型的建立与发展,是当前探索精神分裂症的神经生物学和认知心理学机制的一个关键课题。在加工-保护理论的基础上所建立起来的感觉运动门控精神分裂症模型一直受到普遍的关注。然而,高级认知活动是如何对感觉门控进行调节的这一核心问题目前还有待进一步的解决。本综述围绕着这个核心问题,系统地解释为什么惊反射前脉冲抑制成为目前最为流行的一种精神分裂症的模型,并介绍恐惧情绪学习对感觉运动门控调节作用的最新研究成果,以及阐述这种自上而下的调节作用如何受到在早期发育阶段的社会隔离的影响