Voltammetric determination of cocaine in confiscated samples using a cobalt hexacyanoferrate film-modified electrode

In this work, a fast, non destructive voltammetric method for cocaine detection in acetonitrile medium using a platinum disk electrode chemically modified with cobalt-hexacyanoferrate (CoHCFe) film is described. The deposition of CoHCFe film at platinum disk (working electrode) was carried out in aqueous solution containing NaClO₄ at 0.1 mol L⁻¹ as supporting electrolite. Stability studies of the film and subsequent voltammetric analysis of cocaine were made in acetonitrile medium with NaClO₄ at 0.1 mol L⁻¹ as supporting electrolite. A reversible interaction between cocaine and CoHCFe at the film produces a proportional decrease of original peak current, due to the formation of a complex between cocaine and cobalt íons, with subsequent partial passivation of the film surface, being the intensity of current decrease used as analytical signal for cocaine. A linear dependence of cocaine detection was carried out in the range from 2.4 × 10⁻⁴ to 1.5 × 10⁻³ mol L⁻¹, with a linear correlation coefficient of 0.994 and a detection limit of 1.4 × 10⁻⁴ mol L⁻¹. The analysis of confiscated samples by the proposed method indicated cocaine levels from 37% to 95% (m/m) and these results were validated by comparison to HPLC technique, being obtained good correlation between both methods.     

Characterization of lesions in hanging deaths

Hanging is a common method of committing suicide and a routine task in medico-legal autopsies. The hanging mark is the most relevant external sign and its characteristics are well known, but, for unknown reasons, there are major differences in reports on internal findings. We retrospectively studied 228 consecutive cases of hanging deaths. A complete standard autopsy was performed for every case. We investigated the association between the characteristics of the hanging mark and the frequency of bone, cartilage, soft tissue, and vascular injuries with the mode of suspension. Most cases (75.3%) presented some kind of bone or cartilage fracture, but these were unrelated to any of the variables studied. Vascular lesions are clearly more infrequent: intimal injuries were found in the carotid artery (9.1%), the jugular vein (2.2%), and ruptures of the carotid adventitial layer (21.7%). These could be partially associated with the use of a hard fixed noose and body weight.     

‘Gunboats of soft power’: Boris on Africa and post-Brexit ‘Global Britain’

As Britain prepares to leave the European Union after the popular vote of June 2016, the government is embarking on the revision of foreign policy. Boris Johnson, or ‘just Boris’, has been entrusted with forging the new ‘Global Britain’ for the post-Brexit era and reinventing British economy around new relationships. Boris has a track record of misrepresenting and offending foreign peoples, leaders and countries. This article assesses the prospects for Africa in Johnson’s vision for ‘Global Britain’ as presented in his foreign policy speeches. The paper unpacks Johnson’s discursive construction of ‘Africa’ and inserts it into a broader historical and political context of British relations with Africa. It argues that, by constructing Africa as a ‘problem’ and offering liberal values as a condition for development, Johnson is continuing British imperial and post-colonial discourses of ‘developing’ or ‘civilizing’ Africa. In the post-Brexit world of a changing global balance of power, democratic conditionality serves to sustain and reproduce British forms of power and policies.     

Differential Registration Bias in Voter File Data: A Sensitivity Analysis Approach

The widespread availability of voter files has improved the study of participation in American politics, but the lack of comprehensive data on nonregistrants creates difficult inferential issues. Most notably, observational studies that examine turnout rates among registrants often implicitly condition on registration, a posttreatment variable that can induce bias if the treatment of interest also affects the likelihood of registration. We introduce a sensitivity analysis to assess the potential bias induced by this problem, which we call differential registration bias. Our approach is most helpful for studies that estimate turnout among registrants using posttreatment registration data, but it is also valuable for studies that estimate turnout among the voting‐eligible population using secondary sources. We illustrate our approach with two studies of voting eligibility effects on subsequent turnout among young voters. In both cases, eligibility appears to decrease turnout, but these effects are found to be highly sensitive to differential registration bias.     

Comparing Inference Approaches for RD Designs: A Reexamination of the Effect of Head Start on Child Mortality

The regression discontinuity (RD) design is a popular quasi‐experimental design for causal inference and policy evaluation. The most common inference approaches in RD designs employ “flexible” parametric and nonparametric local polynomial methods, which rely on extrapolation and large‐sample approximations of conditional expectations using observations somewhat near the cutoff that determines treatment assignment. An alternative inference approach employs the idea of local randomization, where the very few units closest to the cutoff are regarded as randomly assigned to treatment and finite‐sample exact inference methods are used. In this paper, we contrast these approaches empirically by re‐analyzing the influential findings of Ludwig and Miller ( 2007 ), who studied the effect of Head Start assistance on child mortality employing parametric RD methods. We first review methods based on approximations of conditional expectations, which are relatively well developed in the literature, and then present new methods based on randomization inference. In particular, we extend the local randomization framework to allow for parametric adjustments of the potential outcomes; our extended framework substantially relaxes strong assumptions in prior literature and better resembles other RD inference methods. We compare all these methods formally, focusing on both estimands and inference properties. In addition, we develop new approaches for randomization‐based sensitivity analysis specifically tailored to RD designs. Applying all these methods to the Head Start data, we find that the original RD treatment effect reported in the literature is quite stable and robust, an empirical finding that enhances the credibility of the original result. All the empirical methods we discuss are readily available in general purpose software in R and Stata; we also provide the dataset and software code needed to replicate all our results.     

Outline Shape Analysis on the Trochlear Constriction and Olecranon Fossa of the Humerus: Insights for Sex Estimation and a New Computational Tool,

Sex estimation through visual analysis of the distal humerus can contribute to establishing the biological profile of an unidentified skeletal individual. Using statistical shape modeling, the trochlear constriction open curves and olecranon fossa closed outlines of 151 humeri were digitized and analyzed. The shape configurations exhibited strikingly different degrees of sexual dimorphism when evaluated using linear discriminant analysis with leave‐one‐out cross‐validation. The trochlear constriction performed poorly, correctly classifying 63.6% of the individuals. However, the olecranon fossa showed high sexual dimorphism, presenting a 94.0% accuracy. A simpler model using only two principal components was also generated. While the accuracy is slightly inferior (88.1%), it has the advantage of being constrained to bidimensional components that were translated into morphoscopic variables within a simulator interface. This allowed us to implement the method through a web application that does not require users to be trained in landmark digitization or have knowledge of geometric morphometrics.     

The spectre of Haiti: structural antiblackness,the far-right backlash and the fear of a black majority in Brazil

Abstract

This article situates the far-right backlash in Brazil within the larger Latin American context, including its colonial legacy, leftist governments’ failure to deliver promises of inclusion, and the US–China geopolitical dispute over the region’s strategic natural resources. By situating Bolsonaro’s electoral victory within these dynamics, our analysis presents an alternative to two common perspectives. First, studies of the region’s political moment and of Brazilian society in particular do not pay enough attention to institutional and everyday racism, and instead focus mostly on comparative analysis of governmental policies and social class dynamics. Second, critical perspectives that take into account racial inequalities are often not attuned to structural dynamics of gendered antiblackness, and instead present racism as a broad set of practices that negatively affect non-white people in related manners. Our context-specific analysis of the electoral reemergence of the far right in Brazil aims at contributing to an understanding of persistent dynamics of racial inequality within the region as part of a long, enduring and foundational odium of Black people.     

Differential Ability of Necrophagous Diptera to Colonize Concealed Resources: Empirical Evidence From a Field Experiment in Brazil

Field studies in forensic entomology seem to assume that a cadaver is a resource equally accessible to flies, irrespective of the species’ size, behavior, and sensorial capacity. We aimed to challenge this assumption by experimentally manipulating baited traps in order to test whether the accessibility to decomposing baits is related to the following: (i) the diversity of necrophagous dipterans; (ii) the body size of adults; and (iii) the female sexual maturity stage. The experiment was performed in a rainforest fragment in Northeastern Brazil, in an area characterized by high levels of homicides. Traps baited with decomposing chicken liver had three levels of access: easy (six openings on the trap), intermediate (three), and difficult (one). A total of 750 adults of Calliphoridae, Fanniidae, Muscidae, Phoridae, and Sarcophagidae were collected. Of the 18 species recorded, Megaselia scalaris was the most abundant (46.8%) followed by Lucilia eximia (29.7%) and Chrysomya megacephala (9.8%). The number of species increased significantly with the accessibility level, but overall abundance did not differ, as a consequence of the numerical dominance of M. scalaris. A strong female bias (>91%) was observed in all traps. For Calliphoridae specimens, 90% of the females caught in traps under intermediate and difficult access were sexually mature. By empirically demonstrating that limitation of access and exclusion of visual stimuli do not deter several dipteran species from reaching a substrate, we expand the knowledge on the factors that can shape the colonization of concealed human cadavers, including variables such as insect size and stage of sexual maturity.