STOCHASTIC KINETIC MODELS: DYNAMIC INDEPENDENCE, MODULARITY AND GRAPHS

The dynamic properties and independence structure of stochastic kinetic models (SKMs) are analyzed. An SKM is a highly multivariate jump process used to model chemical reaction networks, particularly those in biochemical and cellular systems. We identify SKM subprocesses with the corresponding counting processes and propose a directed, cyclic graph (the kinetic independence graph or KIG) that encodes the local independence structure of their conditional intensities. Given a partition [A, D, B] of the vertices, the graphical separation A ⊥ B|D in the undirected KIG has an intuitive chemical interpretation and implies that A is locally independent of B given A ∪ D. It is proved that this separation also results in global independence of the internal histories of A and B conditional on a history of the jumps in D which, under conditions we derive, corresponds to the internal history of D. The results enable mathematical definition of a modularization of an SKM using its implied dynamics. Graphical decomposition methods are developed for the identification and efficient computation of nested modularizations. Application to an SKM of the red blood cell advances understanding of this biochemical system.     

Blessed assurance: Religion, anxiety, and tranquility among US adults

A growing body of research investigates the possible relationships between religion and mental health. After developing a series of arguments linking various aspects of religion with anxiety and tranquility, we test relevant hypotheses using data from the 1996 General Social Survey. Results show that frequency of religious attendance and the belief in an afterlife are inversely associated with feelings of anxiety and positively associated with feelings of tranquility. However, frequency of prayer has no direct association with either outcome. Strong beliefs in the pervasiveness of sin are positively linked with anxiety but unrelated to tranquility. Finally, belief in an afterlife and frequency of prayer buffer the adverse effects of poor health and financial decline on anxiety. Implications of these findings are discussed along with study limitations and promising directions for future research.     

Children's Expression of Emotional Meaning in Music Through Expressive Body Movement

Recent research has demonstrated that preschool children can decode emotional meaning in expressive body movement; however, to date, no research has considered preschool children's ability to encode emotional meaning in this media. The current study investigated 4- (N = 23) and 5- (N = 24) year-old children's ability to encode the emotional meaning of an accompanying music segment by moving a teddy bear using previously modeled expressive movements to indicate one of four target emotions (happiness, sadness, anger, or fear). Adult judges visually categorized the silent videotaped expressive movement performances by children of both ages with greater than chance level accuracy. In addition, accuracy in categorizing the emotion being expressed varied as a function of age of child and emotion. A subsequent cue analysis revealed that children as young as 4 years old were systematically varying their expressive movements with respect to force, rotation, shifts in movement pattern, tempo, and upward movement in the process of emotional communication. The theoretical significance of such encoding ability is discussed with respect to children's nonverbal skills and the communication of emotion.     

Application of the characterization theory to the mixture model

This paper indicates the potential application of the characterization theory to the mixture model. It discusses a particular example of a mixture model and concludes that successful application of this theory can be made in order to choose the appropriate mixture model and the mixing parameter.     

Incomplete variance functions

Estimates of variance from samples depend strongly on extreme values. Incomplete variance functions may be used to explain the unreliability of variance estimates when the distribution is long-tailed.     

Severity of illness: red herring or horse of different color? Part 2.

In this continuation of his article, the author defines severity and acuity of illness and discusses approaches to the measurement of the two factors. He provides some background on severity of illness measures that are in current use and prepares for a discussion of the uses of these measures.     

Crime,antisocial personality and pathological gambling

To investigate the hypothesized causal relationship between pathological gambling and gambling-related illegal behaviors, 77 patients seeking behavioral treatment for excessive gambling and 32 members of Gamblers Anonymous were administered a structured interview schedule. Data on the incidence, nature and extent of both gambling and non-gambling related illegal behaviors was obtained and DSM-III (A.P.A., 1980) criteria for Antisocial personality were used as the measure of sociopathy.Of the sample, 54.1% admitted to a gambling related offense and 21.1% were charged. Results showed that 14.6% met DSM-III criteria for Antisocial Personality, Four subgroups were subsequently identified; gamblers who committed no offense (36.7%), gambling only offenses (40.4%), non-gambling only offenses (9.2%) or both gambling and non-gambling offenses (13.7%). Significantly more subjects from the gambling plus non-gambling related offenses subgroup were classified as antisocial personalities.Of pathological gamblers who committed offenses, two thirds reportedly did so as a direct consequence of gambling induced problems. Subjects reporting gambling-only related offenses showed a significant increase in antisocial features after adolescence suggesting that antisocial features emerge as a secondary phenomenon to pathological gambling behavior patterns.Acknowledgments: This study was made possible by a grant from the Criminology Research Council, Australian Institute of Criminology.