Contextual Stress and Health Risk Behaviors Among African American Adolescents

This study examined the longitudinal association between contextual stress and health risk behaviors and the role of protective factors in a community epidemiologically-defined sample of urban African American adolescents (N = 500; 46.4% female). Structural equation modeling was used to create a latent variable measuring contextual stress (community violence, neighborhood disorder, and experiences with racial discrimination). Contextual stress in 8th grade was associated with aggressive behavior and substance use 2 years later for boys. For girls, contextual stress predicted later substance use, but not aggressive behavior. High academic competence and self-worth reduced the impact of contextual stress on substance use for boys. Implications for intervention and directions for future research on health risk behaviors among African American adolescents are discussed.     

Speaking the language of security: the Commonwealth,the Francophonie and the CPLP in conflict management in Africa

The last decade has seen an unprecedented increase in conflict management activities in Africa by international organisations. This has been accompanied by a flurry of academic publications and of policy reports that stress the comparative advantages at the legal and operational levels of regional and other intergovernmental organisations. The article assesses this dominant favourable view by examining the role of the Commonwealth, the Francophonie and the CPLP in Africa. Traditionally regarded as cultural organisations, they have gradually extended their profile to include a security mandate. Drawing from fieldwork and an extensive review of the literature, the article presents the first comparative study of the conflict management activities of these organisations in Africa.     

Quantification of human mitochondrial DNA using synthesized DNA standards

Successful mitochondrial DNA (mtDNA) forensic analysis depends on sufficient quantity and quality of mtDNA. A real-time quantitative PCR assay was developed to assess such characteristics in a DNA sample, which utilizes a duplex, synthetic DNA to ensure optimal quality assurance and quality control. The assay's 105-base pair target sequence facilitates amplification of degraded DNA and is minimally homologous to nonhuman mtDNA. The primers and probe hybridize to a region that has relatively few sequence polymorphisms. The assay can also identify the presence of PCR inhibitors and thus indicate the need for sample repurification. The results show that the assay provides information down to 10 copies and provides a dynamic range spanning seven orders of magnitude. Additional experiments demonstrated that as few as 300 mtDNA copies resulted in successful hypervariable region amplification, information that permits sample conservation and optimized downstream PCR testing. The assay described is rapid, reliable, and robust.     

Comparison of glass fragments using particle-induced X-ray emission (PIXE) spectrometry

A procedure has been developed to analyze the trace element concentrations in glass fragments using particle-induced X-ray emission (PIXE) spectrometry. This method involves using accelerated protons to excite inner-shell electronic transitions of target atoms and recording the resultant X-rays to characterize the trace element concentrations. The protocol was able to identify those glass fragments that originated from different sources based on their elemental analyses. The protocol includes specific approaches to calculating uncertainties and handling measurements below the level of detection. The results indicate that this approach has increased sensitivity for several elements with higher atomic number compared with X-ray fluorescence methods. While not as sensitive as laser-ablation or inductively coupled plasma mass spectrometry methods of dissolved samples, it is entirely nondestructive and entails a much simpler sample preparation process that may be used to presort glass fragments for more comprehensive elemental analysis. As such, the technique described may have a niche role in forensic glass analysis.     

Fatal suicidal crossbow injury--the ability to act

We report a case of a 58-year-old man who committed suicide using a modern crossbow. The victim shot himself in the chest with a conical field-tip arrow from close proximity. We first presumed that this was a case of homicide committed with a firearm. We were, however, subsequently proved wrong. The reasons for the primary statement were as follows: the external morphology of the entrance wound being typical of a firearm discharged from long distance; the perforation found on the victim's clothing; the absence of the firearm at the place of death; the absence of the arrow in the wound. All of these reasons forced us initially to conclude that the case was one of homicide. In the reported case, the man, after having been shot with an arrow, was further able to act, even though the abdominal aorta and liver were seriously injured. While the arrow was in the wound, the injuries may not have led to massive bleeding because of incomplete tamponade of the defects by the arrow shaft. Pulling the arrow out of the victim's wound track initiated massive bleeding. Despite all these injuries, the man was capable of pulling the bow string again and reloading the crossbow with the arrow used in the first attempt. This case demonstrates that forensic investigations into crossbow injuries can be very difficult, especially when the bolt has been removed from the body.     

Age-at-death estimation by pulp/tooth area ratio in canines: study of a 20th-century Mexican sample of prisoners to test Cameriere's method

Accurate age estimation has always been a problem for forensic scientists, and apposition of secondary dentine is often used as an indicator of age. Cameriere et al. studied the pulp/tooth area ratio by peri-apical X-ray images of the canines, to observe the apposition of secondary dentine. The present study examines the application of this technique in a Mexican identified sample coming from the Department of Physical Anthropology of the INAH, at Mexico City. The main aim of this work is to test the reliability of this method in a skeletal sample of a specific population, different from the samples used for its development. The obtained regression model explained 96.2% of total variance (R(2) = 0.962) with a standard error of estimate of 1.909 and a standard deviation of 1.947. These results demonstrate great reliability and that the age/secondary dentine relationship is not variable in this specific population.