Estimating the propagation rate of a viral infection of potato plants via mixtures of regressions

A problem arising from the study of the spread of a viral infection among potato plants by aphids appears to involve a mixture of two linear regressions on a single predictor variable. The plant scientists studying the problem were particularly interested in obtaining a 95% confidence upper bound for the infection rate. We discuss briefly the procedure for fitting mixtures of regression models by means of maximum likelihood, effected via the EM algorithm. We give general expressions for the implementation of the M-step and then address the issue of conducting statistical inference in this context. A technique due to T. A. Louis may be used to estimate the covariance matrix of the parameter estimates by calculating the observed Fisher information matrix. We develop general expressions for the entries of this information matrix. Having the complete covariance matrix permits the calculation of confidence and prediction bands for the fitted model. We also investigate the testing of hypotheses concerning the number of components in the mixture via parametric and 'semiparametric' bootstrapping. Finally, we develop a method of producing diagnostic plots of the residuals from a mixture of linear regressions.     

Problem Gambling Inside and Out: The Assessment of Community and Institutional Problem Gambling in the Canadian Correctional System

This paper reports on the results of a multi-site survey of gambling behaviour and gambling problems amongst offenders in correctional institutions in Ontario, Canada, conducted between 2008 and 2011. A total of 422 (completion rate 61.5 %) incarcerated offenders (381 male and 41 female) took part in the study including 301 federal offenders and 121 provincial offenders. Based on the Problem Gambling Severity Index of the Canadian Problem Gambling Index (CPGI/PGSI) the prevalence rate of severe problem gambling was 8.9 prior to incarceration and 4.4 % during incarceration. These numbers are substantially higher than rates found among the general public. Thirty-four percent of the sample reported gambling in prison. Half of those who suffered from gambling problems before incarceration continued to have gambling problems during incarceration. People with problems related to slot machines prior to incarceration reported fewer gambling problems during incarceration compared to other problem gamblers.     

Self,Emotions, and Extreme Violence: Extending Symbolic Interactionist Theorizing

Extreme violence revolves around actions of individuals who are emotionally aroused and willing to kill themselves, if need be, to inflict harm on enemies. Terrorism, gangbanging, and genocide are conspicuous examples of extreme violence. This violence is ultimately driven by repressed negative emotions about self that are transmuted into variants of anger and combinations of anger with satisfaction‐happiness to produce emotions such as hatred, righteous anger, and vengeance. This theory combines symbolic interactionism's emphasis on identity and self with key ideas from gestalt theories, psychoanalytic theories, and interaction ritual theory as well as data from primatology, evolutionary biology, and neurology. I explain extreme violence as the outcome of several converging forces: the neurological capacity for humans as evolved apes to experience and express a large palate of high‐intensity emotions, the experience of shame in key institutional spheres, the repression of shame (and, at times, guilt and alienation as well as other highly charged negative emotions), the intensification and transmutation of these repressed emotions into variants and elaborations of anger, the making of external attributions blaming external targets for negative experiences, the portrayal of these targets in highly negative terms, and the charging up of positive emotions in interaction rituals directed at inflicting harm on external enemies.     

Evaluation of scientific merit in col laboratories: A new look at an old question

What role can information science play in promoting public understanding of science and technology? In order to answer this question, it is important to understand the new perspective which is emerging for research in the information science field. Internet, and the information superhighways announced both in Europe and the United States, are increasingly focusing attention on computer‐mediated communication within research communities. “Collaboratories”; is the name given to work aimed at using computer‐based technologies to help promote the social processes of knowledge production. One goal of information science lies in efforts to measure the contribution of technical devices to knowledge production practices. This is called infometrics research; it requires a clear understanding of how the social system of science regulates information flows to promote these practices.     

Social Control and Emotions

This is the first article in Symbolic Interaction's symposium in tribute to Tamotsu (Tom) Shibutani (1920–2004). The author, a student in Shibutani's graduate course on social control, discusses his teacher's ideas and their evolution into his own. The article provides ample basis for the author's observation: a scholar's contribution can be measured not only by the cumulative corpus of his or her published work, but also by the influence that this individual has had on the work of others.