Corrosion behaviour of four handguns in aqueous environments: Corrosion product characterization and effects on estimating the time since deposition

When a firearm has been disposed of in a body of water and becomes corroded, its appearance is altered and determining a time-since-immersion may be of import to the investigation. Therefore, in this study, the corrosion and mass loss of four handgun slides over a period of 180 days were examined. Solid-state characterization of the metals and their corrosion products via SEM/EDX and powder X-ray Diffraction (pXRD) was performed. The pXRDs were analyzed against the NIST Powder Diffraction Database to determine the crystalline phases. Filings from the SS416 standard, Llama and Ruger handgun slide predominantly consisted of iron alloys. After 180-days in solution, pXRD indicated that the adherent corrosion products consisted of 1) γ-FeOOH and 2) iron oxide (Fe₃O₄ or Fe₂O₃). Additionally, pXRD analysis indicated that the adherent corrosion products of the SS416 standard also consisted of CrO₃. Metal filings from the Raven and Jennings handgun slides were a mixture of iron–nickel–zinc and EDX and pXRD analyses of the corrosion products, when submersed in deionized water, indicated that the products consisted of: 1) γ-FeOOH, 2) iron oxide (Fe₃O₄ or Fe₂O₃), and 3) ZnFe₂O₄ or ZnO; where the Jennings adherent rust contained ZnFe₂O₄ and the Raven adherent rust contained ZnO. Further, pXRD of the corrosion products from these alloys, when submersed in 25 PSU (Practical Salinity Unit) solution, indicated that the products consisted of: 1) ZnO, 2) Zn(OH)₂, 3) α-Ni(OH)₂, and 4) NaCl.The data thus indicated that both metal composition and the presence of chloride ions had significant impacts on rates and products of corrosion and suggest that the presence of Cl^? changes not only the rate of corrosion, but also the corroding species itself. While mechanisms and rates of the chloride driven corrosion processes offer explanations as to the different oxides and hydroxides observed between immersion conditions, they do not offer an explanation for the differences observed between handguns. Therefore, utilizing a general approach where surface area coverage of corrosion products is the sole consideration is not sufficient to determine time-since-immersion. Attempts to determine a time-since-immersion would require a priori knowledge of the mechanism of corrosion for a given metal mixture within a specified environment. The results described herein give indications as to the possible corrosion mechanism driving the process in high and low Cl^? environments and show the necessity of including the metal composition, rust composition and ion concentration in any models that attempt to elucidate the time-since-immersion of handguns for forensic applications.     

Comparative partitions

Genre is often conceptualised as a product or text. Such a view, however, seems to downplay the dynamism of textual production encouraging a hermeneutics with rigid, formulaic tendencies. This is clearly evident in the contribution of many structural linguists such as Martin and Hasan to the study of genre. While semioticians, notably Kress, Threadgold and Freadman, have critiqued this position there is still considerable work to be undertaken in reconceptualising notions of genre to give emphasis to the pragmatic play of language use.

This paper uses a TV current affairs interview of the controversial author Helen Demidenko‐Darville as the basis for examining approaches to the study of genre. The analysis is framed by Deleuze and Guattari's metaphor of ‘the map’ which it is argued captures the fluidity and generative nature of the interpretation of genre espoused in this article. It is presented as an alternative to metaphors such as ‘the frame’, ‘the recipe’, ‘the game’, and ‘the template’ which form the basis of theorisations of genre that tend to focus on the stability of form and, as such, have difficulty in accounting for the rupturing of boundaries which is evident in the Demidenko interview.

What distinguishes the map from the tracing is that it is entirely oriented toward an experimentation in contact with the real ... the map is open and connectable in all of its dimensions; it is detachable, reversible, susceptible to constant modification. It can be torn, reversed, adapted to any kind of mounting, reworked by an individual, group, or social formation ... A map has multiple entryways, as opposed to the tracing, which always comes back “to the same”;. The map has to do with performance, whereas the tracing always involves an alleged ‘competence’.     

A partial assessment of South Carolina's Project Safe Neighborhoods strategy: Evidence from a sample of supervised offenders

Since 2001, the federal Project Safe Neighborhoods initiative has instituted a comprehensive effort to reduce gun crimes in local communities across the United States. In South Carolina, the United States Attorney's Office for the District of South Carolina established Project CeaseFire, a localized response to reduce the prevalence of gun crime through targeted prosecution and increased public education. One element of Project CeaseFire was carried out by the South Carolina Department of Probation, Parole, and Pardon Services. The current study utilized a quasi-experimental design to compare firearm-related incidents among a random sample of offenders under community supervision prior to and after the implementation of the SCDPPPS CeaseFire program. Although incidents involving a firearm were rare, the current results did not indicate a reduction in firearm-related incidents among offenders entering supervision after the SCDPPPS CeaseFire program was implemented. Instead, an increase in firearm incidents was observed after CeaseFire implementation. Possible explanations for the observed results are offered along with limitations to the study and policy implications.     

Selection Bias and Continuous-Time Duration Models: Consequences and a Proposed Solution

This article analyzes the consequences of nonrandom sample selection for continuous-time duration analyses and develops a new estimator to correct for it when necessary. We conduct a series of Monte Carlo analyses that estimate common duration models as well as our proposed duration model with selection. These simulations show that ignoring sample selection issues can lead to biased parameter estimates, including the appearance of (nonexistent) duration dependence. In addition, our proposed estimator is found to be superior in root mean-square error terms when nontrivial amounts of selection are present. Finally, we provide an empirical application of our method by studying whether self-selectivity is a problem for studies of leaders' survival during and following militarized conflicts.     

Elemental Analysis of Variably Contaminated Cremains Using X‐ray Fluorescence Spectrometry

Analyzing and identifying skeletal remains becomes increasingly difficult when remains have been cremated, especially in cases where the cremated material may have been intentionally contaminated with nonskeletal material. This study examined the potential of X‐ray fluorescence spectrometry (XRF) to detect the presence of nonskeletal contaminants in samples of cremains. Eleven samples of cremains were variably combined with concrete mix and analyzed using XRF. Photon counts of elements in each sample were analyzed, and the coefficient of determination (R²) using unweighted linear regression as a function of percent cremains was calculated. Results showed that with changes in the proportion of skeletal material and contaminant, there were significant (R² > 0.90) changes in detected levels of phosphorus, potassium, zinc, aluminum, and sulfur. The use of XRF is concluded to be a valid approach in the identification of the presence of nonskeletal material in potentially contaminated cremains.     

Perceptions and use of videoconferencing in forensic mental health assessments: A survey of evaluators and legal personnel

ABSTRACT

The use of videoconferencing (VC) to conduct forensic mental health assessments (FMHA) is increasing. Yet, little is known about its acceptability among clinicians or legal professionals. In Study 1 (N?=?156), forensic evaluators were asked about their use of VC, reasons for its use, and opinions about the validity, usefulness, ethics, and legality of its use. An estimated one-third of evaluators have used VC in the past. Although evaluators overall expressed moderate concern over the ethics and legality of use, prior experience appeared to mitigate concerns. Younger practitioners were also more open to using VC. Reduced costs for courts was the most frequently endorsed benefit associated with VC, while restricted ability to administer psychological testing and potential technological problems were seen as the biggest disadvantages. In Study 2 (N?=?27), attorneys and judges were surveyed about frequency with which they encounter VC for FMHA and their perceptions about the validity of those assessments. Findings indicated legal personnel expressed rather negative views without having much first-hand experience of VC, including concerns about establishing rapport and technical difficulties. These studies have implications for whether VC will be adopted more frequently in FMHA.