Inferring ancestral origin using a single multiplex assay of ancestry-informative marker SNPs

Tests that infer the ancestral origin of a DNA sample have considerable potential in the development of forensic tools that can help to guide crime investigation. We have developed a single-tube 34-plex SNP assay for the assignment of ancestral origin by choosing ancestry-informative markers (AIMs) exhibiting highly contrasting allele frequency distributions between the three major population-groups. To predict ancestral origin from the profiles obtained, a classification algorithm was developed based on maximum likelihood. Sampling of two populations each from African, European and East Asian groups provided training sets for the algorithm and this was tested using the CEPH Human Genome Diversity Panel. We detected negligible theoretical and practical error for assignments to one of the three groups analyzed with consistently high classification probabilities, even when using reduced subsets of SNPs. This study shows that by choosing SNPs exhibiting marked allele frequency differences between population-groups a practical forensic test for assigning the most likely ancestry can be achieved from a single multiplexed assay.     

Investigating polyurethane foam as a form of trace evidence.

The aim of this study was to determine whether polyurethane (PU) foam fragments from different sources could be discriminated from each other. Low and high power microscopy was used to determine whether or not foam fragments were distinguishable from each other under various lighting conditions. Once similar foam fragments were declared microscopically indistinguishable, the visible range microspectrophotometer was highly competent in further distinguishing the spectral characteristics in various fragments from each other. Foam fragments from the same source were shown to display no microscopical or chemical variation. Conversely, it was possible to make clear distinctions between foam fragments from different sources.     

Clinically Significant Trauma Symptoms and Behavioral Problems in a Community-based Sample of Children Exposed to Domestic Violence

This study assessed the associations of characteristics of domestic violence incidents with clinically significant levels of traumatic symptoms and behavioral problems in a socio-economically and ethnically mixed sample of 687 children participating in a community-service program for children witnessing violence. Study predictors included child/family demographic characteristics, type and chronicity of exposure, and child’s perceptions of control over the event and threat to personal safety. Outcomes consisted of traumatic symptoms and behavior problems. Results showed that perceived threat and control were associated with greater odds of clinically significant levels of several trauma symptoms (and behavior problems in the case of perceived threat) after adjusting for effects of demographic factors and violence characteristics. Child co-victimization increased odds of reaching clinically significant levels of traumatic symptoms compared to children who witnessed the event but were not victimized. Female sex and White ethnicity increased odds of specific trauma symptoms and behavior problems. Increasing age reduced odds of some trauma symptoms. Associations between predictors and one outcome measure did not generalize across the other outcome measure. Implications of study findings, and directions for future research are discussed.     

Assessing Readiness to Change among Perpetrators of Intimate Partner Violence: Analysis of Two Self-report Measures

Recent interest in the construct of motivation to change among male perpetrators of intimate partner violence (IPV) has led to development of two self-report measures of this construct: the University of Rhode Island Change Assessment for Domestic Violence (URICA-DV; Levesque et al. 2000) and the Safe at Home Inventory (SAH; Begun et al. 2003). We examined the internal structure of these instruments using confirmatory and exploratory factor analyses in a sample of 199 male IPV perpetrators waiting to begin court-mandated batterer intervention programs. Results indicated that the scales had adequate internal consistency. However, using confirmatory factor analyses, the hypothesized structural models of each instrument fit the data poorly. Subsequent models suggested by a series of exploratory factor analyses failed to improve model fit substantially for both scales. For the URICA-DV, a 3-factor model including items from the Precontemplation, Contemplation, and Action subscales fit the data adequately. No acceptable model fit could be found for the SAH. Intercorrelations among similar subscales across the two inventories suggested only a modest degree of intercorrelation (r’s = 0.16–0.52), and a factor structure more dependent on scale of origin than item latent content, suggesting that the scales assess different facets of the readiness to change construct. These results suggest that before the stages of change construct can be fully applied to the IPV area, more research and evaluation are needed on how to accurately assess abuser readiness to change.     

Criteria for differentiating self- or other-inflicted injuries of alleged or real victims

A synoptic study of six cases of self-inflicted sharp force injuries is presented, where young, mostly female people had simulated assaults to gain sympathy or other personal advantage. The morphological distinctives of simulated assault wounds from such of real assault are worked out and the common situative and motivative background is cleared up.