Pistol bullet deflection through soft tissue simulants.

Trajectory deflections of pistol bullets from four different firearms, fired through soft tissue simulants under two different incidence and exit angles were studied. The data from this study can be used in reconstructions of shooting incidents where human soft tissues (not bones) were perforated with pistol bullets and assumptions must be made about bullet deflection in order to correctly reconstruct trajectories. The results demonstrate that deflection was influenced by the length of the "wound channel" through the simulants. In short, deflection was small to virtually absent with 5 and 10cm channel lengths. With channel lengths of 15, 20 and 25cm, there was a clear increase in deflection and/or a more erratic deflection behaviour with most shots. The data also suggest an influence of the angle of incidence and/or exit on both the direction and the magnitude of the deflection.

Likelihood ratio methods for forensic comparison of evaporated gasoline residues.

In the investigation of arson, evidence connecting a suspect to the fire scene may be obtained by comparing the composition of ignitable liquid residues found at the crime scene to ignitable liquids found in possession of the suspect. Interpreting the result of such a comparison is hampered by processes at the crime scene that result in evaporation, matrix interference, and microbial degradation of the ignitable liquid. Most commonly, gasoline is used as a fire accelerant in arson. In the current scientific literature on gasoline comparison, classification studies are reported for unevaporated and evaporated gasoline residues. In these studies the goal is to discriminate between samples of several sources of gasoline, based on a chemical analysis. While in classification studies the focus is on discrimination of gasolines, for forensic purposes a likelihood ratio approach is more relevant. In this work, a first step is made towards the ultimate goal of obtaining numerical values for the strength of evidence for the inference of identity of source in gasoline comparisons. Three likelihood ratio methods are presented for the comparison of evaporated gasoline residues (up to 75% weight loss under laboratory conditions). Two methods based on distance functions and one multivariate method were developed. The performance of the three methods is characterized by rates of misleading evidence, an analysis of the calibration and an information theoretical analysis. The three methods show strong improvement of discrimination as compared with a completely uninformative method. The two distance functions perform better than the multivariate method, in terms of discrimination and rates of misleading evidence.

Elemental analysis of 3,4-methylenedioxymethamphetamine (MDMA): A tool to determine the synthesis method and trace links.

The elemental composition of 3,4-methylenedioxymethamphetamine (MDMA) powders and tablets was determined. The objective was the identification of the synthesis method and application of the elemental profile in comparative analysis. The developed analytical method comprised the digestion of a sample followed by quantitative analysis with inductive coupled plasma mass spectrometry (ICP-MS) and inductive coupled plasma atomic emission spectroscopy (ICP-AES). The sample collection consisted of a unique set of MDMA powders (57) from illicit production sites and MDMA tablets (97) taken from large seizures (over 500 tablets) in the Netherlands. The production method of MDMA could be determined for 89 of the 97 tablets. In 84 cases reductive amination using Pt as the catalyst was used, in four cases reductive amination using NaBH(4) or a similar reducing agent was employed and one mixed sample (Pt and B) was found. None of the MDMA tablets were assigned to the aluminium amalgam method. Using the elemental profile, 13 links were identified within the 97 MDMA tablets using cluster analysis based on Pearson correlations. Of these links 10 were corroborated by additional analyses.

Persistent high rates of hysterectomy in Western Australia: a population-based study of 83 000 procedures over 23 years.

OBJECTIVE: To investigate incidence trends and demographic, social and health factors associated with the rate of hysterectomy and morbidity outcomes in Western Australia and compare these with international studies. DESIGN: Population-based retrospective cohort study. SETTING: All hospitals in Western Australia where hysterectomies were performed from 1981 to 2003. POPULATION: All women aged 20 years or older who underwent a hysterectomy. METHODS: Statistical analysis of record-linked administrative health data. MAIN OUTCOME MEASURES: Rates, rate ratios and odds ratios for incidence measures and length of stay in hospital and odds ratios for morbidity measures. RESULTS: The age-standardised rate of hysterectomy adjusted for the underlying prevalence of hysterectomy decreased 23% from 6.6 per 1000 woman-years (95% CI 6.4-6.9) in 1981 to 4.8 per 1000 woman-years (95% CI 4.6-4.9) in 2003. Lifetime risk of hysterectomy was estimated as 35%. In 2003, 40% of hysterectomies were abdominal. The rate of hysterectomy to treat menstrual disorders fell from 4 per 1000 woman-years in 1981 to 1 per 1000 woman-years in 1993 and has since stabilised. Low socio-economic status, having only public health insurance, nonindigenous status and living in rural or remote areas were associated with increased risk of having a hysterectomy for menstrual disorders. Indigenous women had higher rates of hysterectomy to treat gynaecological cancers compared with nonindigenous women, particularly in rural areas. The odds of a serious complication were 20% lower for vaginal hysterectomies compared with abdominal procedures. CONCLUSION: Western Australia has one of the highest hysterectomy rates in the world, although proportionally, significantly fewer abdominal hysterectomies are performed than in most countries.

Partial least-squares regression for routine analysis of urinary calculus composition with Fourier transform infrared analysis.

Quantitative assessment of urinary calculus (renal stone) constituents by infrared analysis (IR) is hampered by the need of expert knowledge for spectrum interpretation. Our laboratory performed a computerized search of several libraries, containing 235 reference spectra from various mixtures with different proportions. Library search was followed by visual interpretation of band intensities for more precise semiquantitative determination of the composition. We tested partial least-squares (PLS) regression for the most frequently occurring compositions of urinary calculi. Using a constrained mixture design, we prepared various samples containing whewellite, weddellite, and carbonate apatite and used these as a calibration set for PLS regression. The value of PLS analysis was investigated by the assay of known artificial mixtures and selected patients' samples for which the semiquantitative compositions were determined by computerized library search followed by visual interpretation. Compared with that method, PLS analysis was superior with respect to accuracy and necessity of expert knowledge. Apart from some practical limitations in data-handling facilities, we believe that PLS regression offers a promising tool for routine quantification, not only for whewellite, weddellite, and carbonate apatite, but also for other compositions of the urinary calculus.