Modelling data from single-photon emission computerized tomography

The completely random character of radioactive disintegration provides the basis of a strong justification for a Poisson linear model for single-photon emission computed tomography data, which can be used to produce reconstructions of isotope densities, whether by maximum likelihood or Bayesian methods. However, such a model requires the construction of a matrix of weights, which represent the mean rates of arrival at each detector of photons originating from each point within the body space. Two methods of constructing these weights are discussed, and reconstructions resulting from phantom and real data are presented.     

Reactions to Job Content Plateaus: Examining Role Ambiguity and Hierarchical Plateaus as Moderators

Plateauing research often reveals a negative relationship between job content plateauing (i.e., lacking challenge in one's job) and work attitudes. This study explores situations where job content plateauing is associated with fewer negative work attitudes, revealing role ambiguity (i.e., being unclear about job duties and responsibilities) and hierarchical plateauing (i.e., low likelihood of promotions) as moderators of the job content plateau‐work attitude relationship. Specifically, job content plateaued employees reported greater job satisfaction and organizational commitment if they were not also experiencing a hierarchical plateau. Job content plateaued employees also reported greater job satisfaction when role ambiguity was low.     

Goal Ambiguity and Organizational Performance in U.S. Federal Agencies

In spite of numerous observations that government organizationshave high levels of organizational goal ambiguity that exertmajor influences on their other characteristics, few researchershave measured goal ambiguity and tested these frequent assertions.In previous research, we developed measures of four dimensionsof goal ambiguity: mission comprehension ambiguity, directivegoal ambiguity, evaluative goal ambiguity, and priority goalambiguity. Confirming hypotheses developed from the literatureon public organizations, the latter three variables showed relationsto such organizational characteristics as organizational age,financial publicness (proportion of funding from governmentallocations), and regulatory status. This article reports asecond analytical step of examining the relations between thegoal ambiguity dimensions and indicators of organizational performancebased on responses to the 2000 National Partnership for ReinventingGovernment Survey of federal employees. The performance variablesincluded managerial effectiveness, customer service orientation,productivity, and work quality. Regression analyses with numerouscontrol variables found that directive, evaluative, and prioritygoal ambiguity related negatively to managerial effectiveness.All four performance indicators showed significant negativerelationships with evaluative goal ambiguity and directive goalambiguity. The results provide further evidence of the viabilityof the new measures of goal ambiguity, support theory-basedbut previously untested hypotheses, and further indicate thefeasibility and value of analyzing goal ambiguity of governmentorganizations.     

A LOTTO SYSTEMS PROBLEM

A Lotto Systems bet allows the player to nominate n numbers from which (s)he believes the winning six numbers will be drawn, and to bet on all combinations of six of these n numbers. Assume that the winning six numbers come from the nominated n. How many combinations must be entered to guarantee that one combination will include at least five of the winning six numbers? The problem is generalized in this paper, and the method of simulated annealing is used to find solutions for various situations. The case where two supplementary numbers are drawn after the initial six winning numbers is also considered.     

Between Spatial and Social Segregation among Immigrants: The Case of Immigrants from the FSU in Israel

Studies on immigrants' residential concentration have reported mixed findings. Some have argued that immigrants' residential concentration is a necessary step in the process of their social integration because there the newcomers find housing and employment opportunities as well as social support. As they learn the language and improve their socioeconomic status, they move to neighborhoods where they share space with the native population. Others have argued that the ethnic neighborhood delays the process of social integration in the new society because it nurtures informal ethnic social networks that provide incomplete information and retard the process of language acquisition. The study reported here investigated the effect of motivations, perceptions of attitudes of the host society, acculturation and socioeconomic factors on immigrants' residential concentration. It also sought to expand previous research by examining the relationship between immigrants'residential concentration and social relationships with nonimmigrants. Data for the study were collected in 1999 through a survey of immigrants from the FSU who had settled in one northern city in Israel after 1989. The results show a negative relationship of socioeconomic status and fluency in Hebrew with the percentage of immigrants residing in a given neighborhood. The higher the socioeconomic status and the more fluent the immigrant in Hebrew, the lower the percentage of immigrants in his or her neighborhood. Immigrants who expressed a proactive motivation for migration resided in neighborhoods with a low percentage of immigrants. Immigrants' residential concentration was not found to be related to the development of social relationships with the local population. The implications of the findings are discussed.     

Dealing with Toxicity in the Risk Society: The Case of the Hamilton,Ontario Plastics Recycling Fire*

Une perspective de la construction sociale sert de cadre a l'analyse des controverses sur la gestion des risques qui ont été provoquées à la suite d'un incendie majeur dans une usine de recyclage de matières plastiques à Hamilton, en Ontario. En mettant l'accent sur les processus de réclamation au c?ur de l'interaction entre les représen‐tants du gouvernement, les acteurs environnementaux, les experts techniques et les résidants, il a été révélé qu'un accent trop limité aux questions d'ordre technique avait mené a l'exclusion des préoccupations fondées sur la rationalité culturelle ayant ainsi entraine un cadre d'interaction très litigieux divisant profondément. Les conséquences des conclusions empiriques de la thése de la société des risques ainsi que de la théorie sur la communication des risques sont explorées. A social construction perspective is applied in the analysis of the risk management controversies that arose in response to a large toxic fire that occurred at a Hamilton, Ontario plastics recycling facility. By focussing on the claimsmaking processes involved in the interaction of government officials, environmental movement actors, technical experts, and residents, it was found that an overly narrow focus on technical matters led to the exclusion of lay concerns based on cultural rationality, thereby resulting in a very contentious and divisive setting for interaction. Implications of the empirical findings for the risk society thesis and risk communication theory are explored.     

Betrayal and repetition: Understanding aggression in sexually abused girls

Betrayal by a significant object is seen as primary in causing behavioral and emotional disturbances in incest victims, leading to a pervasive identification with the aggressor and disturbances in object relations development. Identification with the aggressor is understood not as a uniform defense mobilized against a specific affect but as a complex compromise formation which defends against anxiety, while also providing libidinal, aggressive and superego gratifications. Far from simply attempting to overcome the past, identifications thus preserve affects that have become pleasurable and self-defining. Two case studies of adolescent girls illustrate how treatment can help victims recognize and begin to forego the sadomasochistic pleasure derived from these identifications, a relinquishment necessary for true mastery.     

The Role of Cancer Risk in the Regulation of Industrial Pollution

The extent of carcinogen regulation under existing U.S. environmental statutes is assessed by developing measures of the scope and stringency of regulation. While concern about cancer risk has played an important political role in obtaining support for pollution control programs, it has not provided the predominant rationale for most regulatory actions taken to date. Less than 20% of all standards established to limit concentrations of chemicals in various media address carcinogens. Restrictions on chemical use are more frequently based on concerns about noncancer human health or ecological effects. Of the chemicals in commercial use which have been identified as potential human carcinogens on the basis of rodent bioassays, only a small proportion are regulated. There is an inverse relationship between the scope of regulatory coverage and the stringency of regulatory requirements: the largest percentages of identified carcinogens are affected by the least stringent requirements, such as information disclosure. Standards based on de minimis cancer risk levels have been established for only 10% of identified carcinogens and are restricted to one medium: water. Complete bans on use have affected very few chemicals. The general role that carcinogenicity now plays in the regulatory process is not dramatically different from that of other adverse human health effects: if a substance is identified as a hazard, it may eventually be subject to economically achievable and technically feasible restrictions.