Testing Application of Geographical Information Systems,Forensic Geomorphology and Electrical Resistivity Tomography to Investigate Clandestine Grave Sites in Colombia,South America

Colombian forensic investigators required assistance locating clandestine burials of missing persons related to human right atrocities from 14 years ago. Geoscientific search methods were trialled, including a predictive spatial statistical model, using various input and database information, to select the most likely grave locations in difficult mountainous terrain. Groundwork using forensic geomorphology, near-surface geophysics (ERT) and subsequent probing identified suspect burial positions. One site was in mountainous terrain and the other in former school grounds, both difficult to access and in poor weather conditions. In the mountainous area, a negative resistivity anomaly area was identified and intrusively investigated, found to be a buried rock. In school grounds, after MESP and intelligence were used to identify a burial site, surface depressions were identified, and ERT datasets collected over the highest priority depression; intrusive investigations discovered a hand-dug pit containing animal bones. This approach is suggested for Latin American searches.     

Evaluation of the Simultaneous Analysis of Organic and Inorganic Gunshot Residues Within a Large Population Data Set Using Electrochemical Sensors*,†

The increasing demand for rapid methods to identify both inorganic and organic gunshot residues (IGSR and OGSR) makes electrochemical methods, an attractive screening tool to modernize current practice. Our research group has previously demonstrated that electrochemical screening of GSR samples delivers a simple, inexpensive, and sensitive analytical solution that is capable of detecting IGSR and OGSR in less than 10 min per sample. In this study, we expand our previous work by increasing the number of GSR markers and applying machine learning classifiers to the interpretation of a larger population data set. Utilizing bare screen-printed carbon electrodes, the detection and resolution of seven markers (IGSR; lead, antimony, and copper, and OGSR; nitroglycerin, 2,4-dinitrotoluene, diphenylamine, and ethyl centralite) was achieved with limits of detection (LODs) below 1 µg/mL. A large population data set was obtained from 395 authentic shooter samples and 350 background samples. Various statistical methods and machine learning algorithms, including critical thresholds (CT), naïve Bayes (NB), logistic regression (LR), and neural networks (NN), were utilized to calculate the performance and error rates. Neural networks proved to be the best predictor when assessing the dichotomous question of detection of GSR on the hands of shooter versus nonshooter groups. Accuracies for the studied population were 81.8 % (CT), 88.1% (NB), 94.7% (LR), and 95.4% (NN), respectively. The ability to detect both IGSR and OGSR simultaneously provides a selective testing platform for gunshot residues that can provide a powerful field-testing technique and assist with decisions in case management.     

A Count Data Model of Technology Adoption

This paper investigates the main determinants of the adoption of flexible production technologies (FPTs), using a plant-level dataset of Portuguese manufacturing industry. Besides using a new dataset, this paper extends the framework of previous studies on technology adoption by taking into account the effect of demand uncertainty as an additional determinant of adoption. In order to examine this relationship, several econometric models for count data are estimated. These models deal with the discrete nature of the dependent variable and firm specific unobservable characteristics arising from the cross-section context. The main findings of the paper are: (i) rank effects and technological regimes are important determinants of technology adoption, as put forward in previous models of technology diffusion; (ii) demand uncertainty has a significant positive impact on the likelihood of adopting FPTs, which suggests that technological heterogeneity is important when modelling firms' investment decisions; (iii) the estimates were improved after controlling for excess zeros and overdispersion that characterizes our data.     

STR allelic frequencies for an African population sample (Equatorial Guinea) using AmpFlSTR Identifiler and Powerplex 16 kits

We present allele frequencies and forensic parameters for 17 STRs included in the AmpFlSTR Identifiler (CSF1PO, D2S1338, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D19S433, D21S11, FGA, TH01, TPO and VWA) and Powerplex 16 System (CSF1PO, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, FGA, Penta D, Penta E, TH01, TPO and VWA) in a sample of 134 unrelated individuals from Equatorial Guinea located in Western Africa, between Cameroon and Gabon. Hardy-Weinberg equilibrium was tested for each locus and the sample was compared with five African databases: Promega's and AB Applied Biosystems African-Americans and samples from Mozambique, from Cabinda (Angola) and Guinea-Bissau.     

Population data on 14 STR loci from population of Serbia and Montenegro (new and renewed data)

A renewed and new population study of fourteen short tandem repeat loci (TH01, TPOX, CSF1P0, vWA, FES/FPS, F13A01, D13S317, D7S820, D16S539, LPL, F13B, CD4, D5S818 and D8S1179) were performed in a sample of 296-531 unrelated individuals from Serbia and Montenegro. Population data were compared to previously published data from Vojvodina province and neighboring Croatia.     

Methods for the analysis of hard dental tissues exposed to high temperatures

The preservation of teeth that have been exposed to a heat source is a key factor in order to keep their value as evidence. This research paper presents some methods under development for the analysis of dental evidence after exposure to high temperatures; it also establishes age related alterations of young and aged teeth which have been exposed to direct heat. A total of thirty permanent healthy teeth (young=15 and old=15) were submitted to direct heat (n=14) and to a controlled raise of temperature (n=16); they were embedded in polymethylmetacrilate. For the macroscopic study, blocks were cut in half, polished and their surfaces were digitalized. Subsequently, blocks were put in slides, worn away and observed through a photomicroscope. The study of the colorimetric pattern was done by Corel Photo Paint 12.0 and Image J. software. All teeth submitted to the gradual raise of temperature presented a degree of structural damage lower than those exposed to direct heat. The internal surface of young teeth exposed to direct heat showed lines of fracture oblique to the long axis of the tooth; in contrast, a reticular pattern was observed on aged teeth. All teeth exposed to direct heat showed some matte-black coloration areas, while those submitted to a gradual increment of temperature showed a greyish colour in the enamel and a chalky-white in the cementum. By using both thermal treatments in young teeth, the amelodentinal junction was lost, thus preserving the integrity of each tissue. In aged teeth, the separation of this junction was produced because of the breakdown of the dentine. Microscopically, in teeth exposed to direct heat, it was neither possible to differentiate the dentin from the cementum, nor to distinguish the incremental lines of the latter; while in those submitted to a controlled increment of temperature, the corresponding morphology in the tissues was observed. A significant statistical difference was obtained for black colour among young and aged teeth exposed to direct heat, as well as among the means of all colours obtained from the teeth exposed to both treatments. The structural changes observed allow locating a tooth in the studied age groups. Our results show the viability of the applied method for the processing of samples, allowing their preservation as evidence during an indefinite time.     

The Real Winner's Curse

Traditional theories of democracy suggest that political representation of excluded groups can reduce their incentives to engage in conflict and lead to lower violence. However, this argument ignores the response of established elites when (1) their interests are threatened by the policy stance of new political actors and (2) elites have a comparative advantage in the exercise of violence. Using a regression discontinuity approach, we show that the narrow election of previously excluded left‐wing parties to local executive office in Colombia results in a one standard deviation increase in violent events by right‐wing paramilitaries. We interpret this surge in violence as a reaction of traditional elites to offset the increase in outsiders' access to formal political power. Consistent with this interpretation, we find that violence by left‐wing guerrillas and other actors is unaffected and that violence is not influenced by the victory of right‐wing or other new parties in close elections.