Complex mixtures: A critical examination of a paper by Homer et al.

DNA evidence in criminal cases may be challenging to interpret if several individuals have contributed to a DNA-mixture. The genetic markers conventionally used for forensic applications may be insufficient to resolve cases where there is a small fraction of DNA (say less than 10%) from some contributors or where there are several (say more than 4) contributors. Recently methods have been proposed that claim to substantially improve on existing approaches [1]. The basic idea is to use high-density single nucleotide polymorphism (SNP) genotyping arrays including as many as 500,000 markers or more and explicitly exploit raw allele intensity measures. It is claimed that trace fractions of less than 0.1% can be reliably detected in mixtures with a large number of contributors. Specific forensic issues pertaining to the amount and quality of DNA are not discussed in the paper and will not be addressed here. Rather our paper critically examines the statistical methods and the validity of the conclusions drawn in Homer et al. (2008) [1].We provide a mathematical argument showing that the suggested statistical approach will give misleading results for important cases. For instance, for a two person mixture an individual contributing less than 33% is expected to be declared a non-contributor. The quoted threshold 33% applies when all relative allele frequencies are 0.5. Simulations confirmed the mathematical findings and also provide results for more complex cases. We specified several scenarios for the number of contributors, the mixing proportions and allele frequencies and simulated as many as 500,000 SNPs.A controlled, blinded experiment was performed using the Illumina GoldenGate^® 360 SNP test panel. Twenty-five mixtures were created from 2 to 5 contributors with proportions ranging from 0.01 to 0.99. The findings were consistent with the mathematical result and the simulations.We conclude that it is not possible to reliably infer the presence of minor contributors to mixtures following the approach suggested in Homer et al. (2008) [1]. The basic problem is that the method fails to account for mixing proportions.     

History of Abuse and Current Suicidal Ideation: Results from a Population Based Survey

The relationship between a history of physical or sexual abuse and current suicidal ideation was examined in the current study based on data from the Washington state 2002 Behavioral Risk Factor Surveillance System (BRFSS). Out of the total sample of 4081, 1058 indicated they had experienced either physical or sexual abuse before the age of 18, 52 indicated they had experienced physical abuse in the past 12 months, and 210 indicated they had been forced to have sex since the age of 18. Additionally, 106 indicated they had seriously considered committing suicide in the past year. After controlling for such factors as age, gender, income, education, race, employment and marital status and the interactions between different abuse risk factors using multivariate logistic regression, results showed that a history of childhood physical (OR = 2.31, 95% CI = 1.364, 3.90) or sexual (OR = 2.72, 95% CI = 1.58, 4.67) abuse and adult physical (OR = 27.30, 95% CI = 11.64, 64.01) or sexual (OR = 5.87, 95% CI = 3.24, 10.63) abuse all were related to current suicidal ideation. Implications for future research are discussed.     

The sensitivity and specificity of the RSID™-saliva kit for the detection of human salivary amylase in the Forensic Science Laboratory,Dublin, Ireland

We demonstrate here that the RSID?-saliva test can be used as a test for human salivary α-amylase on samples routinely examined in forensic casework. We show that the RSID?-saliva test detects salivary α-amylase at lower concentrations than the Phadebas^® Quantitative test, that the RSID?-saliva test does not cross-react with forensically important human fluids and that the RSID?-saliva test can be successfully integrated into the whole swab semen extraction method.     

Mother Abuse: A Matter of Youth Justice,Child Welfare or Domestic Violence?

International evidence suggests that in advanced welfare states the abuse of parents, most particularly mothers, by their (most frequently male) adolescent children is increasingly prevalent. In the United Kingdom, however, child‐to‐mother abuse remains one of the most under‐acknowledged and under‐researched forms of family violence. Although it is an issue shrouded in silence, stigma, and shame, the authors' work in the youth justice sphere, focusing on interventions to deal with anti‐social behaviour, suggests that adolescent violence toward mothers is a topical and prevalent issue. We identify different ways of conceptualizing it in the policy realms of youth justice, child welfare, and domestic violence. The behaviour of both child/young person and mother is constructed in ways which inform the assignment of blame and responsibility. The paper highlights the silence that surrounds the issue in both the policy and wider academic spheres, hiding the failure of service providers to respond to this very destructive form of intimate interpersonal violence.     

Fighting back: Lethal responses to predatory attacks

Each year millions of Americans become victims of predatory crimes. The way victims respond to these attacks varies from complicance with offenders' requests to physically challenging offenders. In some cases, the physical defense of self and property has lethal consequences for the initial offender. While much is known about felony murder victims and typical homicide offenders, little is known about individuals who fight back against predatory attack by using lethal violence. In this paper, we use data from the Homicides in Chicago, 1965–1995 study to describe the characteristics of defensive homicide offenders and to determine how they compare with felony murder victims and defensive homicide offenders. Our results indicate that defensive homicide offenders are more similar to typical homicide offenders than felony murder victims, and are even more likely to have violent criminal histories and to use firearms than typical homicide offenders. Our results challenge the common perception that individuals who fight back against predatory attack are simply “law-abiding citizens.” We conclude the paper with a discussion of the implications of our study for additional research and police practice. Authors' Note: The authors thank editor Dennis Stevens and James Black for their helpful comments on earlier draft of the paper.     

The right not to know and coronary angiography: is the common law of Australia consistent with patients' wishes?

In "The Right Not to Know: Patient Autonomy or Medical Paternalism?" (2000) 7 JLM 286 Judy Gutman qualitatively examined the direction of the law relating to the duty of medical practitioners to disclose information to their patients about risks associated with medical treatment. Prompted by theoretical issues raised in that article, a quantitative study was performed. The study focused on the wishes of patients referred for coronary angiography regarding information about the risks inherent in that procedure. The results of the study contribute to the ongoing academic discussion about risk disclosure and consent to medical treatment and demonstrate a need for further empirical research in the area. The study also highlights the desirability of clinical medical practice conforming to the tenets of the common law and vice versa.     

The relationship between identity status,locus of control,and ego development

Based upon the assumption that identity status, locus of control, and ego stage development are interrelated psychological mechanisms that screen and filter social stimuli, a comparison of the three psychological constructs was completed using 294 college students. Identity achievement students were found to be more advanced in their ego stage development and level of internality, while diffusion students were less advanced. Contrary to expectations, no evidence was found for intraindividual development based upon cross-sectional data.Research interests are personality and social development of adolescents, interpersonal attraction, and family relations.Received her M.S. in human development from Utah State University.