GHB free acid: II. Isolation and spectroscopic characterization for forensic analysis

A reference standard for gamma-hydroxybutyric acid (GHB) free acid is not commercially available, making its analysis in forensic exhibits more difficult. GHB free acid is typically encountered in aqueous solution and in the presence of the lactone, gamma-butyrolactone (GBL), presenting difficulty in Fourier transform infrared (FT-IR) analysis. The strong infrared (IR) absorptivity of the GBL carbonyl band, the shifting of the GBL carbonyl band in aqueous solutions, and the position of the O-H bend for water can mask the main carbonyl band for GHB free acid. Model solutions of beta-hydroxybutyric acid (BHB) and GBL were studied in order to further understand the masking of the GHB free acid carbonyl band in FT-IR analysis. The use of second derivative FT-IR spectroscopy was shown to provide resolution of the free acid carbonyl band, and a presumptive test for GHB free acid was developed and applied. An extension of this work included preparing, for use as a standard reference material, small amounts (< or = 10 mg) of GHB free acid. Preparation was based on the instantaneous reaction of GHB's sodium salt with a stoichiometric amount of hydrochloric acid in aqueous solution, and subsequent isolation of the free acid in neat liquid form. Both FT-IR and proton nuclear magnetic resonance spectra of the neat reference material were obtained and used to verify its identity. The isolation of GHB free acid from actual forensic exhibits is also presented, with identity confirmation using FT-IR.     

How reliable is the sub-population model in DNA testimony?

The performance of the sub-population model first proposed by Balding and Nichols [D.J. Balding, R.A. Nichols, DNA profile match probability calculation: how to allow for population stratification, relatedness, database selection and single bands. Forensic Sci. Int. 64 (1994) 125-140] is examined using a simulation approach. This work extends the investigations of Curran et al. [J.M. Curran, J.S. Buckleton, and C.M. Triggs, What is the magnitude of the sub-population effect? Forensic Sci. Int. 135 (2003) 1-8]. In particular the effect of underestimating the coancestry coefficient, theta, and the effect of departures from the modelling assumptions were investigated. The model tends to give strongly conservative estimates if the estimate for the coancestry coefficient is accurate. If this coefficient is underestimated then a larger fraction of cases give non-conservative estimates. Departures from the modelling assumption that the sub-population is in Hardy-Weinberg and linkage equilibria appear to have very little effect.     

Impulsivity and schemas for a hostile world: postdictors of violent behaviour

Forty male prisoners at a medium-security Canadian penitentiary completed the I Questionnaire, a measure of impulsivity, and two measures of schemas for a hostile world. Both hypervigilance for hostile words during a dichotic shadowing task and hostile attributions made about actors in social vignettes correlated greater than .30 with a criminal history of persistent violence. Impulsivity did not significantly correlate with the schema measures but correlated .30 with persistent violence. The results provide support for the Serin and Kuriychuk model of aggression that links impulsivity and hostile attributions with persistent male violence.     

Development of a human-specific real-time PCR assay for the simultaneous quantitation of total genomic and male DNA

A duplex real-time quantitative PCR assay was developed for forensic DNA analysis, which provides simultaneous quantitation of total genomic human DNA and human male DNA. The assay utilizes two spectrally resolved fluorogenic probes in a 5' nuclease (TaqMantrade mark) assay. Within the range of organisms empirically tested and based upon theoretical specificity using National Center for Biotechnology Information GenBank sequences, primer and probe sequences were shown to be human specific, and the Y-chromosome probe, male-specific. A mixture-challenge study resulted in accurate quantitation of 25 pg male DNA in a mixture of up to 1:5000 (male:female DNA). Additional experimental results include comparisons with the slot blot method and commercial real-time PCR kits. The assay developed addresses the shortcomings of the traditional slot blot method as well as the commercial real-time PCR kits. This method is shown to be specific, relatively simple, rapid, has low limits of detection, and consumes limited sample in addition to reporting both the male and total genomic DNA concentrations present.     

Registrants,Voters, and Turnout Variability Across Neighborhoods

Although political participation has received wide-ranging scholarly attention, little is known for certain about the effects of social and political context on turnout. A scattered set of analyses—well-known by both political scientists and campaign consultants—suggests that ones neighborhood has a relatively minor impact on the decision to vote. These analyses, however, typically rely upon data from a single location. Drawing on official lists of registered voters from sixteen major counties across seven states (including Florida) from the 2000 presidential election, we use geographic/mapping information and hierarchical models to obtain a more accurate picture of how neighborhood characteristics affect participation, especially among partisans. Our research shows that neighborhoods influence voting by interacting with partisan affiliation to dampen turnout among voters we might otherwise expect to participate. Most notably, we find Republican partisans in enemy territory tend to vote less than expected, even after accounting for socioeconomic status. Our findings have implications for campaign strategy, and lead us to suggest that campaign targeting efforts could be improved by an integration of aggregate- and individual-level information about voters.     

Bite mark or bottle top?

An alleged assault was reported by a 42-year-old female, with initial medical examination revealing an apparent bite mark on the right buttock. Odontological examination, including visual assessment, full history and photographs showed that the injury did not meet the class characteristics of a human bite. Subsequent digital overlay production showed that the injury pattern was consistent with a corrugated bottle top. This case highlights the need for careful assessment of injuries alleged to be caused by human teeth.     

Stable isotope ratios as a tool in microbial forensics--Part 1. Microbial isotopic composition as a function of growth medium

The stable isotope ratios of a seized pathogen culture could potentially reveal information about the environment in which the agent was produced. In this paper we describe general relationships between stable isotopes of carbon, nitrogen, and hydrogen in bacteriological culture media and spores of Bacillus subtilis, an endospore-forming soil bacterium. In numerous media that varied both in nutrient composition and water stable isotope ratios, medium to spore enrichment in carbon isotopes was 0.3 +/- 2.0% per thousand (parts per thousand), and in nitrogen, 4.5 +/- 0.7% per thousand. We achieved mass balance for the contribution of hydrogen isotopes from nutrients (70%) and water (30%) to spores in independent experiments by varying the isotope ratios of nutrients or water. A model was derived for predicting the isotope ratio values of spores from those in nutrients and water.