Inelastic Dark Matter at the LHC

We perform a model-independent study of inelastic dark matter at the LHC, concentrating on the parameter space with the mass splitting between the excited and ground states of dark matter above a few hundred MeV, where the direct detection experiments are unlikely to explore. The generic signatures of inelastic dark matter at the LHC are displaced pions together with a monojet plus missing energy, and can be tested at the 7 TeV LHC.Comment: 4 pages, 6 figure

Kernel density classification and boosting: an L2 sub analysis

Kernel density estimation is a commonly used approach to classification. However, most of the theoretical results for kernel methods apply to estimation per se and not necessarily to classification. In this paper we show that when estimating the difference between two densities, the optimal smoothing parameters are increasing functions of the sample size of the complementary group, and we provide a small simluation study which examines the relative performance of kernel density methods when the final goal is classification. A relative newcomer to the classification portfolio is “boosting”, and this paper proposes an algorithm for boosting kernel density classifiers. We note that boosting is closely linked to a previously proposed method of bias reduction in kernel density estimation and indicate how it will enjoy similar properties for classification. We show that boosting kernel classifiers reduces the bias whilst only slightly increasing the variance, with an overall reduction in error. Numerical examples and simulations are used to illustrate the findings, and we also suggest further areas of research

Exposure to substance use in the social environment : the experiences of adolescents in the Tshwane Metropole

The premise of this study is that if exposure to substance use in the social environment of adolescents is understood, macro interventions could be recommended to promote adolescents’ right to live in a safe and sustainable environment. The aim of the study was to explore adolescents’ experiences of exposure to substance use in their social environment, other than the home. A qualitative research approach was adopted and 40 semi-structured interviews were conducted. Adolescent participants, of both genders between 11 and 18 years, were recruited across the Tshwane Metropole. The Social Learning Theory underpinned this study as it offers concepts and principles for understanding how social environmental factors impact on adolescents’ behaviour. Key findings indicated that exposure to substance use is highly prevalent amongst adolescents in the Tshwane Metropole and could be normalised in their social reality. Recommendations are offered for appropriate macro interventions in line with a developmental approach.http://www.uj.ac.za/EN/Faculties/humanities/departments/socialwork/TheSocialWorkPractionerResearcherJournal/Pages/home.aspxam2016Social Work and Criminolog

Evaluating Brightness and Spectral Properties of Click Beetle and Firefly Luciferases Using Luciferin Analogues: Identification of Preferred Pairings of Luciferase and Substrate for In Vivo Bioluminescence Imaging.

Currently, a variety of red and green beetle luciferase variants are available for bioluminescence imaging (BLI). In addition, new luciferin analogues providing longer wavelength luminescence have been developed that show promise for improved deep tissue imaging. However, a detailed assessment of these analogues (e.g., Akalumine-HCl, CycLuc1, and amino naphthyl luciferin (NH <sub>2</sub> -NpLH2)) combined with state of the art luciferases has not been performed. The aim of this study was to evaluate for the first time the in vivo brightness and spectral characteristics of firefly (Luc2), click beetle green (CBG99), click beetle red 2 (CBR2), and Akaluc luciferases when paired with different D-luciferin (D-LH2) analogues in vivo. Transduced human embryonic kidney (HEK 293T) cells expressing individual luciferases were analyzed both in vitro and in mice (via subcutaneous injection). Following introduction of the luciferins to cells or animals, the resulting bioluminescence signal and photon emission spectrum were acquired using a sensitive charge-coupled device (CCD) camera equipped with a series of band pass filters and spectral unmixing software. Our in vivo analysis resulted in four primary findings: (1) the best substrate for Luc2, CBG99, and CBR2 in terms of signal strength was D-luciferin; (2) the spectra for Luc2 and CBR2 were shifted to a longer wavelength when Akalumine-HCl was the substrate; (3) CBR2 gave the brightest signal with the near-infrared substrate, NH <sub>2</sub> -NpLH2; and (4) Akaluc was brighter when paired with either CycLuc1 or Akalumine-HCl when paired with D-LH2. We believe that the experimental results described here should provide valuable guidance to end users for choosing the correct luciferin/luciferase pairs for a variety of BLI applications

Dutch patients, retail chicken meat and poultry share the same ESBL genes, plasmids and strains

Intestinal carriage of extended-spectrum beta-lactamase (ESBL) -producing bacteria in food-producing animals and contamination of retail meat may contribute to increased incidences of infections with ESBL-producing bacteria in humans. Therefore, distribution of ESBL genes, plasmids and strain genotypes in Escherichia coli obtained from poultry and retail chicken meat in the Netherlands was determined and defined as ‘poultry-associated’ (PA). Subsequently, the proportion of E. coli isolates with PA ESBL genes, plasmids and strains was quantified in a representative sample of clinical isolates. The E. coli were derived from 98 retail chicken meat samples, a prevalence survey among poultry, and 516 human clinical samples from 31 laboratories collected during a 3-month period in 2009. Isolates were analysed using an ESBL-specific microarray, sequencing of ESBL genes, PCR-based replicon typing of plasmids, plasmid multi-locus sequence typing (pMLST) and strain genotyping (MLST). Six ESBL genes were defined as PA (blaCTX-M-1, blaCTX-M-2, blaSHV-2, blaSHV-12, blaTEM-20, blaTEM-52): 35% of the human isolates contained PA ESBL genes and 19% contained PA ESBL genes located on IncI1 plasmids that were genetically indistinguishable from those obtained from poultry (meat). Of these ESBL genes, 86% were blaCTX-M-1 and blaTEM-52 genes, which were also the predominant genes in poultry (78%) and retail chicken meat (75%). Of the retail meat samples, 94% contained ESBL-producing isolates of which 39% belonged to E. coli genotypes also present in human samples. These findings are suggestive for transmission of ESBL genes, plasmids and E. coli isolates from poultry to humans, most likely through the food chain

A developmental social work perspective on problematic Internet use among university students

Problematic internet use (PIU) is a growing phenomenon worldwide. Students in higher education especially are a vulnerable group for developing symptoms associated with PIU as a result of the idiosyncratic characteristics of student life. Owing to a lacuna in local social work research on the nature, extent and impact of internet use among students in South Africa, a crosssectional survey was conducted with 498 (n = 498) second-year undergraduate students at a South African university. The results indicate that students access the internet on university campuses and at home daily through their cell phones and laptops for academic and social purposes. Although the average number of hours spent on the internet per day does not indicate PIU, the findings flag certain symptoms associated with PIU, for example, tolerance, escape from problems, and loss of control. Social workers should not be complacent, but rather introduce services to lower students’ risk of PIU. Considering the country’s adoption of social development as welfare model, developmental social work services on the preventive, early intervention and treatment levels as well as policy development are recommended.https://upjournals.co.za/index.php/SWPR/index2020-12-01pm2020Social Work and Criminolog

Review of Economic Instruments in Risk Reduction

Economic instruments (EI), such as subsidies, taxes and insurance-related options are at the heart of discussions regarding novel approaches for managing risk and adapting to climate change, including in the context of multi-stakeholder partnerships (MSP) between the private and public sectors. Although the attractiveness of reducing and managing disasters has long been demonstrated, there is underinvestment into disaster risk management (DRM). A number of factors, such as lack of comprehensive information and cognitive biases are important. In particular, financial constraints and moral hazard, i.e. adverse incentives provided by current arrangements for dealing with disasters rule high. In this line of thinking, instruments that provide a price signal for risk management and incentivize behavioural change hold high appeal to policymakers including the EU. Yet, little is known about such economic instruments, their mechanics, links to risk management and concrete application in the field of disaster risk management (and climate adaptation). Knowledge gaps exist particularly for conditions that create enabling environments for innovative market based EI. Among these are, e.g., the attractiveness for stakeholders in the context of MSP or institutional settings that are required to successfully and efficiently apply the EI. This report reviews key EI according to their potential for managing and incentivising risk management in the context of the ENHANCE project. The guiding questions for this review are: What economic instruments exist for managing disaster risk? How do they contribute to risk management? What innovative options re being discussed? How do case studies plan to discuss and assess economic instruments? The overall aim of this report is to develop an inventory of EI as they support risk management generally and their anticipated uptake in the ENHANCE cases studies. This report first discusses the methodology and the mechanics of EI. Next it presents the market-based and risk financing instruments; finally it concludes with a synthesis of our findings and next steps for the case studies, which are being carried out as part of the ENHANCE project

Electron transport in nanotube--molecular wire hybrids

We study contact effects on electron transport across a molecular wire sandwiched between two semi-infinite (carbon) nanotube leads as a model for nanoelectrodes. Employing the Landauer scattering matrix approach we find that the conductance is very sensitive to parameters such as the coupling strength and geometry of the contact. The conductance exhibits markedly different behavior in the two limiting scenarios of single contact and multiple contacts between the molecular wire and the nanotube interfacial atoms. In contrast to a single contact the multiple-contact configuration acts as a filter selecting single transport channels. It exhibits a scaling law for the conductance as a function of coupling strength and tube diameter. We also observe an unusual narrow-to-broad-to-narrow behavior of conductance resonances upon decreasing the coupling.Comment: 4 pages, figures include

Reddening law and interstellar dust properties along Magellanic sight-lines

This study establishes that SMC, LMC and Milky Way extinction curves obey the same extinction law which depends on the 2200A bump size and one parameter, and generalizes the Cardelli, Clayton and Mathis (1989) relationship. This suggests that extinction in all three galaxies is of the same nature. The role of linear reddening laws over all the visible/UV wavelength range, particularly important in the SMC but also present in the LMC and in the Milky Way, is also highlighted and discussed.Comment: accepted for publication in Astrophysics and Space Science. 16 pages, 12 figures. Some figures are colour plot