Approximating probability density functions in hybrid Bayesian networks with mixtures of truncated exponentials

Mixtures of truncated exponentials (MTE) potentials are an alternative to discretization and Monte Carlo methods for solving hybrid Bayesian networks. Any probability density function (PDF) can be approximated by an MTE potential, which can always be marginalized in closed form. This allows propagation to be done exactly using the Shenoy-Shafer architecture for computing marginals, with no restrictions on the construction of a join tree. This paper presents MTE potentials that approximate standard PDF’s and applications of these potentials for solving inference problems in hybrid Bayesian networks. These approximations will extend the types of inference problems that can be modelled with Bayesian networks, as demonstrated using three examples.     

Book Review: Shell,Greenpeace and Brent Spar,by Grant Jordan. Palgrave,New York, 2001

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations -     

Fathers-The Secondary Partners: Professional Perceptions and Fathers' Reflections

SUMMARY. The following is an account of a research project exploring the recollections of seven fathers at the time of the birth of their children with Down's Syndrome. It discusses the disclosure of diagnosis and subsequent contacts the fathers made both professionally and socially during the period following both in the hospital and at home. This is combined with the personal recollections of one father, not part of the original study, whose child was born with special needs. The implications for both professional practice and fathers are highlighted. Whilst there is an acknowledgement that the project was small scale, the conclusions will raise challenging issues for further discussion both among professionals and individual members of families.     

The spatial structure of epidemic emergence: geographical aspects of poliomyelitis in north-eastern USA, July-October 1916

Summary.  The great epidemic of poliomyelitis which swept New York City and surrounding territory in the summer of 1916 eclipsed all previous global experience of the disease. We draw on epidemiological information that is included in the seminal US Public Health Bulletin 91, 'Epidemiologic studies of poliomyelitis in New York City and the northeastern United States during the year 1916' (Washington DC, 1918), to re-examine the spatial structure of the epidemic. For the main phase of transmission of the epidemic, July–October 1916, it is shown that the maximum concentration of activity of poliomyelitis occurred within a 128-km radius of New York City. Although the integrity of the poliomyelitis cluster was maintained up to approximately 500 km from the metropolitan focus, the level and rate of propagation of disease declined with distance from the origin of the epidemic. Finally, it is shown that the geographical transmission of the epidemic in north-eastern USA probably followed a process of mixed contagious–hierarchical diffusion.     

Immigrants' Language Skills: The Australian Experience in a Longitudinal Survey

This article is concerned with the determinants of English language proficiency (speaking, reading and writing) among immigrants. It presents a model of immigrant destination language proficiency based on economic incentives, exposure to the destination language, and efficiency in second language acquisition. A unique data set, the Longitudinal Survey of Immigrants to Australia, is used to test the model. This survey had three waves, at about six months, eighteen months and three‐and‐a‐half years after immigration. The analyses are performed by wave, type of language skill and gender using probit analysis. Bivariate probit analysis is used across waves. The hypotheses are supported by the data. The bivariate probit analysis indicates a positive correlation in the unexplained component that declines with time between waves, suggesting a “regression to the mean” in the unobserved components of English language proficiency.     

Monsters in cyberspace cyberphobia and cultural panic in the information age

This paper explores popular attitudes toward the Internet (and computer-mediated communication more generally) by mapping some of the more threatening, transgressive and 'monstrous' images associated with cyberspace. An account of risk consciousness is developed in three parts: (1) comparisons with earlier information technologies reveals similarities and differences with regard to public attitudes toward cyberspace and its risks; (2) the development of a model of contemporary teratological space derived from images of boundary-dissolving threats, intrusive alterities and existential ambivalences created by the erosion of binary distinctions and hierarchies; and (3) possible historical and sociological explanations of cyberpanic drawing on recent theorizations of globalization (capitalism/information society theory, risk society theory, reflexive modernization theory, and alterity theory).     

COLLECTIVE MEMORY AND HISTORY:

Abraham Lincoln's changing relation to the African American community of memory is a means of addressing unresolved problems in the work of Maurice Halbwachs. Many sociologists, beginning with Halbwachs, have recognized that commemorative symbolism creates new images of the past, but the process by which this occurs has never been closely studied. I draw on a variety of sources, including Lincoln Day observances, press commentary, oratory, cartoons, and prints, in my effort to understand how commemorative symbolism works. During the past century, no new information about Lincoln's racial attitudes has appeared; yet commemorative pairing and coupling mechanisms and their resulting commemorative networks have transformed him from a conservative symbol of the status quo during the Jim Crow era into the personification of racial justice and equality during the New Deal and the civil rights movement. Since the symbolic devices employed to depict Lincoln are shaped by the very historical record they transcend, however, Halbwachs's distinction between fact-based history and symbol-based commemoration must be modified.