A mixed DNA profile controversy revisited

Semaan et al. (J Forensic Res, 2020, 11, 453) discuss a mock case “where eight different individuals [P₁ through P₈] could not be excluded in a mixed DNA analysis. Even though … expert DNA mixture analysis software was used.” Two of these are the true donors. The LRs reported are incorrect due to the incorrect entry of propositions into LRmix Studio. This forced the software to account for most of the alleles as drop-in, resulting in LRs 60–70 orders of magnitude larger than expected. P₁, P₂, P₄, P₅, and P₈ can be manually excluded using peak heights. This has relevance when using LRmix which does not use peak heights. We extend the work using the same two reference genotypes who were the true contributors as Semaan et al. (J Forensic Res, 2020, 11, 453). We simulate three two-donor mixtures with peak heights using these two genotypes and analyze using STRmix?. For the simulated 1:1 mixture, one of the non-donors’ LRs supported him being a contributor when no conditioning was used. When considered in combination with any other potential donors (i.e., with conditioning), this non-donor was correctly eliminated. For the 3:1 mixture, all results correctly supported that the non-donors were not contributors. The low-template 4:1 mixture LRs with no conditioning showed support for all eight profiles as donors. However, the results from pair-wise conditioning showed that only the two ground truth donors had LRs supporting that they were contributors to the mixture. We recommend the use of peak heights and conditioning profiles, as this allows better sensitivity and specificity even when the persons share many alleles.     

Spatial variation of refractive index in a pane of float glass.

In the statistical interpretation of forensic glass evidence it is standard practice to make the assumption of homogeneity of the refractive index (RI) of the source glass, or of localized homogeneity. However, the work of Locke and Hayes showed that, for toughened windscreen glass, this assumption might not be true. This work is well cited, but there appears to have been little follow-on published research. Furthermore, the toughening process is something known to affect the refractive index, and is a process that float glass does not undergo. Float glass is a major component of casework in New Zealand and for that reason it would be interesting to know whether the findings of Locke and Hayes apply when dealing with float glass. In this paper we describe an experiment similar to that of Locke and Hayes, systematically examining the variation of RI in a pane of float window glass. It was found that, although there were no systematic differences in refractive index, there were observable differences across the pane.     

Measuring Policy Success: Evaluating Public Sector Reform in Bhutan

There has been resurgence in evaluation of policy, reflected mostly by an increase in ex ante studies. Although there is a shift towards ex post evaluation, this has been gradual, resulting in a paucity of ex post evaluation literature. To address this gap, we apply a revisionist approach to evaluate a major public sector reform in the Bhutanese civil service. We conclude that it provides a more holistic approach for ex post evaluation policy, and also a more nuanced evaluation which moves us beyond the narrow binary view of success or failure in reform.     

Body image ideals of low-income African American mothers and their preadolescent daughters

Given the high incidence of obesity and obesity-related health problems among low-income African American women, it is both timely and significant to study factors that contribute to obesity in this population. The perception of current body size (body image) and desired body size (body image ideal) has been associated with the development of anorexia and bulimia in white adolescent girls. Body images and ideals may also be related to the development of obesity among African Americans adolescent girls. This study examined the body images and ideals of 27 low-income African American mothers and their 29 preadolescent daughters. Results suggest that there is a relationship between mothers' perceptions of their daughters bodies and their daughters' body images. Preadolescent, low-income, African American girls have normal weight ideals rather than the ultrathin ideals typically found among white girls. Normal weight girls have ideals that are heavier than their body images. This population may be less motivated than those with thinner ideals to engage in behaviors that would prevent the development of obesity during adolescence. Health promotion programs for this population should acknowledge cultural body weight standards.This study was funded by the American Heart Association of Metropolitan Chicago.Received B.A from the University of Pennsylvania. Research interests include cross-cultural studies of body image, eating disorders, health risk perceptions, and health promotion programs.Received Ph.D. from in Clinical Psychology from Long Island University. Research interests include obesity prevention, binge eating, and cultural differences in eating behavior.     

PENDULUM--a guideline-based approach to the interpretation of STR mixtures

Several years ago, a theory to interpret mixed DNA profiles was proposed that included a consideration of peak area using the method of least squares. This method of mixture interpretation has not been widely adopted because of the complexity of the associated calculations. Most reporting officers (RO) employ an experience and judgement based approach to the interpretation of mixed DNA profiles. Here we present an approach that has formalised the thinking behind this experience and judgement. This has been written into a computer program package called PENDULUM. The program uses a least squares method to estimate the pre-amplification mixture proportion for two potential contributors. It then calculates the heterozygous balance for all of the potential sets of genotypes. A list of "possible" genotypes is generated using a set of heuristic rules. External to the programme the candidate genotypes may then be used to formulate likelihood ratios (LR) that are based on alternative casework propositions. The system does not represent a black box approach; rather it has been integrated into the method currently used by the reporting officers at the Forensic Science Service (FSS). The time saved in automating routine calculations associated with mixtures analysis is significant. In addition, the computer program assists in unifying reporting processes, thereby improving the consistency of reporting.