Novel Y-STR typing strategies reveal the genetic profile of the semen donor in extended interval post-coital cervicovaginal samples

For a variety of reasons, some victims of sexual assault provide vaginal samples more than 24-36 h after the incident. In these cases, the ability to obtain an autosomal STR profile of the semen donor from the living victim diminishes rapidly as the post-coital interval is extended. We have used a number of carefully selected Y-STR loci in a variety of multiplex or monoplex formats to extend the post-coital interval from which a genetic profile of the semen donor can be obtained. The proposed Y-STR typing strategies enable the routine detection of the male donor Y-STR haplotype in cervicovaginal samples recovered up to 4 days post-coitus. We attribute our success to a number of factors that significantly improve the sensitivity and specificity of the analysis. Firstly, we utilize a subset of Y-STR loci that have been carefully selected for their superior performance under stressed conditions in both multiplex and monoplex formats. Specifically these loci function with low copy number templates in the presence of a vast excess of potentially confounding female DNA. Secondly, sperm and non-sperm DNA is co-extracted without a differential extraction process to prevent the unnecessary loss of the small number of structurally fragile sperm remaining in the cervicovaginal tract several days after intercourse. Thirdly, low copy number detection is facilitated by increasing the cycle number to 34-35 cycles and by the ability to input up to 450 ng of co-extracted sperm/non-sperm DNA into the PCR reaction without the appearance of confounding female artifacts. Lastly, the proper collection of post-coital cervicovaginal samples, instead of the lower or mid-vaginal tract samples often taken, is required for optimal recovery of sperm for analysis. In this report we demonstrate that our previously described 19 Y-STR loci systems (MPI and MPII) permit a reliable high resolution haplotype determination of the semen donor in cervicovaginal samples taken up to 48 h after intercourse. However, as the post-coital interval is extended further, dramatic loss of signal is observed and haplotype determination of the male donor is no longer possible with MPI and MPII. Nonetheless, subsets of these 19 loci (MPA and MPB) have been developed specifically to detect the male haplotype in samples recovered 4 days after intercourse. Thus, it is possible to derive an 11-19 locus Y-STR profile of the semen donor in cervicovaginal samples recovered 2-4 days after intercourse.     

Estimation of Models with Beta-Distributed Dependent Variables: A Replication and Extension of Paolino's Study

This note replicates and extends Paolino's discussion (2001,Political Analysis 9:325–346) on the estimation of modelswith beta-distributed dependent variables in two ways. First,it introduces an easy-to-use program for estimating the modelusing Stata. Second, it presents a Bayesian estimator for betavariables based on Paolino's model. Results are compared tothose in the original article.     

Democratic Transitions

Przeworski et al. (2000) challenge the key hypothesis in modernization theory: political regimes do not transition to democracy as per capita incomes rise, they argue. Rather, democratic transitions occur randomly, but once there, countries with higher levels of GDP per capita remain democratic. We retest the modernization hypothesis using new data, new techniques, and a three-way rather than dichotomous classification of regimes. Contrary to Przeworski et al. (2000) we find that the modernization hypothesis stands up well. We also find that partial democracies emerge as among the most important and least understood regime types.     

“Racial Threat”, Partisan Climate, and Direct Democracy: Contextual Effects in Three California Initiatives

Does context—racial, economic, fiscal, and political—affect whites’ votes on racially-related ballot propositions? We examine non-Hispanic whites’ voting behavior on three California ballot initiatives: Propositions 187, 209, and 227. Unlike previous analyses that lacked individual-level data and were therefore limited to ecological inference, we combine individual-level data from exit polls with county-level contextual variables in a hierarchical linear model. Racial/ethnic context affected whites’ votes only on Proposition 187, economic context had no influence on vote choice, and the effect of fiscal context was limited to Proposition 227. However, across the propositions, whites’ decisions were shaped by their political context. Thus, we do not find support for the “racial threat” hypothesis across all racially-charged issues.     

The efficacy and effect of racial profiling: A mathematical simulation approach

Racial profiling—the use of race, ethnicity, or national origin by law enforcement officials to make judgments of criminal suspicion—is assessed in terms of its effect on targeted populations and on law enforcement efficiency. A mathematical simulation, comparing multiple profiling and non‐profiling scenarios, is employed. This analysis indicates that racial profiling exacerbates incarceration disparities between groups whether or not the groups differ in criminality rates, and that the long‐term effects of profiling in terms of criminal captures depend on the calibration of profiling rates to criminality rates. The highest long‐term criminal capture rates appear to occur when stop rate ratios match, or are slightly below, criminality rate ratios between groups. When the possibility of a deterrent effect is modeled, profiling appears to yield fewer criminal captures and have little or no crime reduction effect, and may even increase overall crime rates. © 2006 by the Association for Public Policy Analysis and Management     

Media effects on jurors

This article examines the impact on jurors of exposure to media coverage of legal issues. Jurors' decisions may be influenced by a broad range of legally relevant information gleaned from media sources, including newspaper reports, radio and television news, advertising, movies, and televised crime shows and courtroom scenes. The article gives examples of these influences from real-world cases and from simulated research studies. It focuses on the impact of trial-relevant publicity on jurors in cases unrelated to the one being publicized; the ways that media representations of the justice system may influence jurors' expectations and decisions; the influence of insurance company advertisements on jurors' damage awards; and the impact of viewing pornography on jurors' decision making. The paper also explores the psychological processes by which each of these effects may occur and evaluates proposed remedies.I thank Alan Siegel for his comments on an earlier draft.     

The Effects of Limiting Punitive Damage Awards

In response to concerns that jury awards in tort cases are excessive and unpredictable, nearly every state legislature has enacted some version of tort reform that is intended to curb extravagant damage awards. One of the most important and controversial reforms involves capping (or limiting) the maximum punitive damage award. We conducted a jury analogue study to assess the impact of this reform. In particular, we examined the possibility that capping punitive awards would cause jurors to inflate their compensatory awards to satisfy their desires to punish the defendant, particularly in situations where the defendant's conduct was highly reprehensible. Relative to a condition in which punitive damages were unlimited, caps on punitive damages did not result in inflation of compensatory awards. However, jurors who had no option to award punitive damages assessed compensatory damages at a significantly higher level than did jurors who had the opportunity to do so. We discuss the policy implications of these findings.     

Recovery of single source DNA profiles from mixtures by direct single cell subsampling and simplified micromanipulation

Deconvolution of forensic DNA mixtures into their individual component DNA (geno)types is of great investigative value, though often complex and difficult. Two-person mixtures comprising a major and minor contributor are often easily interpreted although, when the DNA ratio of the two individuals is approximately equal (~1:1), deconvolution and interpretation becomes much more difficult. To address this issue, a physical separation of individual-, two- or three- cell subsamples prior to autosomal STR analysis was performed using a simplified micromanipulation technique paired with a decreased reaction volume and increased cycle number PCR. Using this method, single and multiple buccal epithelial cells were collected from a 1:1 two-person mixture (i.e. from individual 'A' and 'B') and directly amplified, omitting standard DNA extraction and purification steps. Single cell subsamples resulted in partial single-source profiles for both contributors while, in accordance with expectations of a quasi-binomial sampling schema, two- and three-cell subsamples resulted in single source informative partial profiles of individual A and individual B as well as complete consensus profiles, and equally mixed 1:1 (2-cell subsamples) and 2:1 (3-cell subsamples) admixed profiles of individual A and B. This proof-of-concept approach shows promise in permitting the DNA deconvolution of mixed samples where the individual contributors are present in similar amounts that would otherwise be difficult to interpret, resulting in an increase in evidentiary value. The subsampling approach can be readily investigated for DNA casework applications without additional investment in costly, new equipment, requiring only a stereo microscope and a tungsten needle.     

Latent Fingermark Aging Patterns (Part II): Color Contrast Between Ridges and Furrows as One Indicator of Degradation

Currently, no established methodology exists to determine degradation patterns of latent fingermarks by visual means. This article is the second in a series of reports exploring quantifiable degradation‐related parameters, which focuses on color contrast changes between fingermark ridges and furrows over time. Experiment variables included type of secretion (eccrine and sebaceous), substrate (glass and plastic), and exposure to natural light (dark, shade, and direct light). Fingermarks were sequentially visualized with titanium dioxide powder and photographed. Image histogram profiles were evaluated and combined with statistical analysis of color data values. Results indicate that sebaceous depositions on glass were generally less degraded by the effect of environmental conditions compared with those on plastic. In addition, aging in darkness was not always the best condition for preservation, and direct exposure to light seemed to inhibit visual degradation under certain conditions. Overall, the technique provided sufficient sensitivity to discern degradation patterns of fingermarks.