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.     

African American Children's Adjustment: The Roles of Maternal and Teacher Depressive Symptoms

This study examined the unique and interactive roles of mother and teacher depressive symptoms in child adjustment in 277 African American single mother‐headed families, as well as whether the associations differed depending on the age and gender of the child. Findings revealed a significant association between maternal depressive symptoms and child depressive symptoms in girls, but not boys. Moreover, the combination of higher levels of both mother and teacher depressive symptoms was associated with the highest level of child depressive symptoms and, for younger children, externalizing symptoms. The importance of considering the multiple social contexts in which children interact is discussed.     

The influence of risk and protective factors on burnout experienced by those who work with maltreated children

The aim of the study was to explore the degree (and type) of burnout and trauma symptoms, personal histories and coping strategies retrospectively reported by those who work with maltreated children and their families. A self‐selected sample of workers (N = 44) completed a self‐report questionnaire assessing childhood maltreatment, family background characteristics, current adjustment, coping strategies and burnout. Workers reported high levels of emotional exhaustion and depersonalization, and a low to moderate sense of personal accomplishment. Family background characteristics predicted the occurrence of maltreatment and current adjustment, and a personal history of maltreatment predicted current trauma symptoms, but not burnout. Workers most frequently used problem‐focused coping strategies and sought social support; however, coping strategies were not associated with the level of either trauma symptoms or burnout. Despite employing positive coping strategies, their efficacy may be affected by other interpersonal, intra‐individual and job resource issues. Copyright © 2002 John Wiley & Sons, Ltd.     

Reasoning With Partial Knowledge

We investigate how sociological argumentation differs from classical first–order logic. We focus on theories about age dependence of organizational mortality. The overall pattern of argument does not comply with the classical monotonicity principle: Adding premises overturns conclusions in an argument. The cause of nonmonotonicity is the need to derive conclusions from partial knowledge. We identify metaprinciples that appear to guide the observed sociological argumentation patterns, and we formalize a semantics to represent them. This semantics yields a new kind of logical consequence relation. We demonstrate that this new logic can reproduce the results of informal sociological theorizing and lead to new insights. It allows us to unify existing theory fragments, and it paves the way toward a complete classical theory.     

Citizenship,Pluralism, and Modern Public Space

The article begins with the realist assumption in political science that posits that political violence and chaos occurs in the absence of the state, and that the international system is congenitally anarchic. Using the Y2K problem and the 11 September 2001 attack on the World Trade Center in New York as two instances of violent political phenomena within global modernity, this article examines notions of citizenship, pluralism, and their relationships with modern public space through the lens of 'public disaster' scenarios in which the breakdown of centralized systems of power tends to lead to chaos. However, public disasters also appear to create the opposite effect of bonding communities together in the face of adversity that leads to greater social cohesion rather than the breakdown of social institutions. The article tries to resolve this apparent enigma through several theories of public space, democracy, and civil society.     

Infants' Ability to Learn Phonetically Similar Words: Effects of Age and Vocabulary Size

What do novice word learners know about the sound of words? Word‐learning tasks suggest that young infants (14 months old) confuse similar‐sounding words, whereas mispronunciation detection tasks suggest that slightly older infants (18–24 months old) correctly distinguish similar words. Here we explore whether the difficulty at 14 months stems from infants' novice status as word learners or whether it is inherent in the task demands of learning new words. Results from 3 experiments support a developmental explanation. In Experiment 1, infants of 20 months learned to pair 2 phonetically similar words to 2 different objects under precisely the same conditions that infants of 14 months (Experiment 2) failed. In Experiment 3, infants of 17 months showed intermediate, but still successful, performance in the task. Vocabulary size predicted word‐learning performance, but only in the younger, less experienced word learners. The implications of these results for theories of word learning and lexical representation are discussed.