Crack Propagation in Teeth: A Comparison of Perimortem and Postmortem Behavior of Dental Materials and Cracks*

Abstract: This study presents a new method for understanding postmortem heat-induced crack propagation patterns in teeth. The results demonstrate that patterns of postmortem heat-induced crack propagation differ from perimortem and antemortem trauma-induced crack propagation patterns. Dental material of the postmortem tooth undergoes dehydration leading to a shrinking and more brittle dentin material and a weaker dentin-enamel junction. Dentin intertubule tensile stresses are amplified by the presence of the pulp cavity, and initiates crack propagation from the internal dentin, through the dentin-enamel junction and lastly the enamel. In contrast, in vivo perimortem and antemortem trauma-induced crack propagation initiates cracking from the external surface of the enamel toward the dentin-enamel junction where the majority of the energy of the crack is dissipated, eliminating the crack’s progress into the dentin. These unique patterns of crack propagation can be used to differentiate postmortem taphonomy-induced damage from antemortem and perimortem trauma in teeth.     

The peripatetic career structure of the British diplomatic establishment, 1919-39

The first part of this article examines the development of the career structure of the British diplomatic establishment after the reforms of 1919-20, arguing that the peripatetic career identified with the prewar Diplomatic Service became increasingly common for all members of the new amalgamated service between the two world wars. The average length of posting to an overseas mission or one of the geographical departments in London seldom exceeded three years or so. The second part of the article then speculates on the impact of the peripatetic career on the effectiveness of the British diplomatic establishment, suggesting that it had both postive and negative impacts.     

‘Can Governments Weather the Storm in the New Communications Climate?’

Government policies of privatisation, contracting-out and de-regulation have been major driving forces of globalisation in and through the communications industry. Ironically, however, globalism makes it increasingly difficult for national and state governments to influence the communications industry at national and state levels respectively. This article argues that globalism challenges governments to manage and develop their own communications systems and activities in ways which counter some of the major features of globalism in the communications industry. The article advocates rolling communications strategies at state and federal levels and outlines ways in which such strategies could develop.     

Concentrated deviance and the “underdass” hypothesis

The “underclass” is perhaps the defining feature of current research in urban distress and of current debates regarding urban policy. The leading measurement strategy (proposed in this journal) is somewhat divorced from the careful specifications of the leading theoretical work (notably that of W. J. Wilson). Several alternative measurement strategies demonstrate that the findings are extremely sensitive to the measurement used. Theory is the only reliable basis for choosing a measurement strategy and for avoiding the empiricist approach taken by other studies. If we cannot identify the best measurement strategy, then there is no basis for further research or for recommending policies.     

Partying,Cruising, and Hanging in the Streets: Gangs,Routine Activities,and Delinquency and Violence in Chicago, 1959–1962

Objectives

Examine relationships between routine activities, character contests in the form of “signifying,” and general delinquency and fighting in a street gang context.

Methods

Samejima’s (Estimation of latent ability using a response pattern of graded scores. Psychometrika monograph supplement 17. Psychometric Society, Richmond, VA, Retrieved 10 Aug 2011, from http://www.psychometrika.org/journal/online/MN17.pdf, 1969) graded response models and multilevel ordinal logistic regression models are estimated using data from Short and Strodtbeck (Group process and gang delinquency. University of Chicago Press, Chicago, 1965) study of street gangs in Chicago, 1959–1962. The primary sample consists of 490 boys representing 10 black gangs, 4 white gangs, 9 black lower-class groups, 4 white lower-class groups, 2 black middle-class groups, and 2 white middle-class groups.

Results

Unstructured and unsupervised socializing with peers significantly increased the likelihood of delinquency among the boys and explained a significant portion of the group-level gang effect. In addition, the more time the boys spent hanging in the streets and attending parties, the more likely they were to participate in signifying, which, in turn, increased their risk of fighting.

Conclusions

Findings provide evidence that gangs contribute to delinquency partly through their effect on the routine activities of members. Findings also suggest that signifying is an important mechanism by which unstructured and unsupervised socializing with peers leads to violence.