STR analysis of artificially degraded DNA-results of a collaborative European exercise

Degradation of human DNA extracted from forensic stains is, in most cases, the result of a natural process due to the exposure of the stain samples to the environment. Experiences with degraded DNA from casework samples show that every sample may exhibit different properties in this respect, and that it is difficult to systematically assess the performance of routinely used typing systems for the analysis of degraded DNA samples. Using a batch of artificially degraded DNA with an average fragment size of approx. 200 bp a collaborative exercise was carried out among 38 forensic laboratories from 17 European countries. The results were assessed according to correct allele detection, peak height and balance as well as the occurrence of artefacts. A number of common problems were identified based on these results such as strong peak imbalance in heterozygous genotypes for the larger short tandem repeat (STR) fragments after increased PCR cycle numbers, artefact signals and allelic drop-out. Based on the observations, strategies are discussed to overcome these problems. The strategies include careful balancing of the amount of template DNA and the PCR cycle numbers, the reaction volume and the amount of Taq polymerase. Furthermore, a careful evaluation of the results of the fragment analysis and of automated allele calling is necessary to identify the correct alleles and avoid artefacts.     

Black women and intimate partner violence: new directions for research

African American women are at elevated risk for nonfatal and lethal intimate partner violence (IPV). Accordingly, the purpose of this article is to review our current knowledge, with a focus on the sociodemographic factors that make this population particularly vulnerable to abuse. Future research directions include using more diverse Black samples, considering how living at the intersection of multiple forms of oppression shapes Black women's experience with violence, exploring the influence of historical events and oppressive images on victimization, and focusing on survivors' resilience and activism.     

Risk factors for sexual victimization among male and female homeless and runaway youth

Risk factors associated with the likelihood of being sexually victimized by a stranger or friend/acquaintance since being on the street was examined among 372 homeless and runaway youth. Young people were interviewed on the streets and in shelters by outreach workers using a systematic sampling strategy. Youth who engaged in more high-risk behaviors were expected to be at greater risk for sexual victimization by both known and unknown assailants. Results indicated that for females, running from home for the first time at an earlier age was associated with sexual victimization by both a stranger and friend/acquaintance. However, engaging in deviant subsistence strategies, survival sex, and grooming predicted being sexually victimized by a friend/acquaintance. For males, survival sex and grooming predicted stranger sexual victimization, whereas sexual orientation was associated with sexual victimization by a friend/acquaintance. Overall, 35% of the sample had been sexually victimized.