Multivariate analysis for estimating the age of a bloodstain

Our objective is to provide crime laboratories with a technique for estimating the age of a bloodstain. Toward that goal, we have used multiplexed, real-time RT-PCR (or qPCR) to determine the relative stability of different-sized segments of the same RNA species as well as differences in stability between two different RNAs' change over time in bloodstains. Our results indicate that a multivariate analysis of the changing ratio of the different RNA segments can be used to differentiate between samples of different ages in the defined population. Bloodstains from 29 of 30 donors could be partitioned into different ages using this technique. Although further improvements will be required before this approach can be implemented in crime laboratories, the multivariate analysis holds promise of providing a reliable approach for temporally linking a bloodstain to the commission of a crime or excluding a bloodstain as being irrelevant to the case in question.     

On Formal Theory and Statistical Methods: A Response to Carrubba, Yuen, and Zorn

e-mail: sign{at}mail.rochester.edu The recent article by Carrubba, Yuen, and Zorn (2007) (CYZ)attempts to relate the strategic random utility models in Signorino(1999, 2002, 2003) and in Signorino and Yilmaz (2003) to existinggame theory practice and to existing statistical techniques.It contributes to this literature by reminding us that comparativestatics analysis can be applied to the equilibria of these models.There are a number of claims in CYZ, however, that require clarification.In particular, the article's primary claim is that comparativestatics analysis, in combination with one of three proposedstatistical estimators, provides a simpler alternative to methodspreviously advocated. This claim (or combination of claims)is incorrect. When one examines the procedure CYZ recommends,it is no simpler for substantive researchers than anything previouslyrecommended. Moreover, none of the proposed estimators are new:they are exactly the same methods introduced in Signorino (1999,2003), in Signorino and Yilmaz (2003), in Signorino, Walker,and Bas (2002), and in Bas, Signorino, and Walker (2007).     

Volunteering and the state

Volunteering participation rates vary greatly across countries even when the potential volunteers’ individual characteristics are controlled. We therefore analyze the volunteers’ motives against the backdrop of the predominant political and economic environment in different countries, focusing on the state’s role in influencing an individual’s decision to volunteer. Combining individual-level data from the European and World Values Survey with macroeconomic and political variables for OECD countries, we identify three channels through which governmental activities influence voluntary labor: size of the state (i.e., amount of public social expenditure), political consensus between voters and the government, and government support for democratization.     

Performance of the Emit® II Plus 6-Acetylmorphine Assay on the Viva-E® analyzer

We evaluated the performance of Emit(?) II Plus 6-Acetylmorphine Assay for human urine screening on the Viva-E(?) analyzer. Precision was evaluated using the cutoff and ±25% controls. Recovery and linearity were studied by spiking 6-acetylmorphine (6-AM) into human urine pools. Accuracy was evaluated using urine specimens and the results were compared to those from GC/MS. Cross-reactivity with structurally related drugs was assessed at different cross-reactant concentrations. Interferences were assessed in the presence of 7.5 and 12.5 ng/mL of 6-AM. The qualitative repeatability coefficients of variation (CV's) ranged from 0.3% to 0.4% and the within-lab CV's ranged from 2.0% to 2.2%. In analyte units (ng/mL), the repeatability CV's ranged from 1.3% to 2.2% and the within-lab CV's ranged from 2.6% to 4.3%. The limit of detection of the assay was found to be 2.1 ng/mL. Recovery was within 15% of expected value. Linearity was 2.1-20 ng/mL. Method comparison showed 99% agreement with GC/MS. The assay had minimal cross-reactivity with morphine, morphine-3-glucuronide, morphine-6-glucuronide and other opioids. No interference was observed with endogenous interferences and structurally unrelated drugs. The assay correctly classified CAP survey samples. The Emit(?) II Plus 6-Acetylmorphine Assay will be a suitable screening method for urine specimens in both qualitative and semi-quantitative analyses.     

Tattoo frequency and types among homicides and other deaths, 2007-2008: a matched case-control study

An estimated 25% of the US population aged 18 to 50 years has a tattoo, which have been associated with markers of high-risk behaviors including alcohol and drug use, violence, carrying weapons, sexual activity, eating disorders, and suicide. This study compares tattoo prevalence and type in a homicide population to those of an age-, race-, and sex-matched control group of nonhomicide deaths. The data for this study were abstracted from autopsy records maintained by the Jefferson County Alabama Coroner/Medical Examiner's Office for the years 2007 and 2008. Odds ratios and 95% confidence intervals for the association between homicide and tattoo presence and characteristics were calculated using conditional logistic regression. There was no association between tattoo presence and death by homicide; however, among blacks, memorial tattoos were significantly more common among homicides compared with other types of deaths (odds ratio, 2.50; 95% confidence interval, 1.10-5.68). The results of the current study suggest that specific types of tattoos, but not all tattoos, may be risk factors for homicide. Other factors, such as race and lifestyle, along with tattoos may need to be considered.     

Recovery of DNA and fingerprints from touched documents

This study investigated the various factors affecting DNA profiling from DNA recovered from fingerprints deposited on paper before and after fingerprint enhancement treatments. The DNeasy^® plant mini kit (QIAGEN^®) was found to improve DNA recovery from paper by over 150% compared with the QIAamp^® mini kit. A significant decrease in the amount of DNA recovered was observed following treatment with DFO and/or Ninhydrin. This decrease in yield did not have a comparably significant effect on the quality of the SGM Plus™ profiles. Furthermore, this study found that whilst certain paper types, such as newspaper, magazine and filter paper allowed for the good recovery of DNA, common office paper and white card, strongly interfered with the recovery of DNA resulting in poor quality profiles.