Mapping Xenophobic Violence in South Africa: Modeling Spatial Relationships between Group Grievances and Opportunities to Measure the Propensity for Xenophobic Violence

Xenophobia can be defined as the hatred or fear of foreigners or strangers or of their politics or culture (Ngwane et al., 2008). This sentiment reached its tipping point in urban areas across the Republic of South Africa in May 2008 when mass, widespread and systematic attacks against African non-nationals took place across the country. Although previous research agrees on who played the various roles during this crisis event (Everatt, 2010), little research has been carried out to create a predictive model to assess where future violence could occur based on a set of conflict indicators. The purpose of this research is to revisit the sociopolitical, geographical and geopolitical landscape of the Republic of South Africa during the year preceding the violence of May 2008 to identify the conflict indicators that worked towards triggering the violence. Once these indicators are identified, they will be geospatially represented through a series of quantitative thematic maps. Findings from this research reveal that there is a positive correlation between conflict indicators and large xenophobic events and the importance of this research lies in its ability to serve as the basis for a conflict prediction model. The ability to geospatially represent the conflict indicators that served to exacerbate xenophobic tensions across the Republic of South Africa leading up to the violence of May 2008 can be duplicated today to identify the geographic locations that are most susceptible to experience a large xenophobic event

KINEMATICS CHANGE IN COUNTERMOVEMENT JUMPS WITH ADDITIONAL LOADS

The aim of this study was to investigate the effect of sex and additional load during countermovement jumps on hip, knee, and ankle joint kinematics. For this purpose, a total of 25 female and male participants performed barbell-loaded countermovement jumps with up to 80% of body mass. No significant main effect of sex on any of the kinematic parameters was found. The additional load resulted in a significant decrease in hip, knee, and ankle joint angles in the sagittal plane and an increase of the absolute performance time. Significant differences were also found in the frontal and transverse plane kinematics. Hence, since changes in kinematics of all three anatomical planes could increase the risk of injury, they should be closely monitored

EFFECTS OF ADDITIONAL LOAD ON LOWER LIMB JOINT WORK AND THE RATIO BETWEEN THE BRAKING AND PROPULSION COUNTERMOVEMENT JUMP PHASE

The purpose of this study was to identify the effect of additional load on lower limb joint work and joint work ratio between the braking and propulsion countermovement jump (CMJ) phase. Thirteen male sport students performed CMJ with five different loads up to 80% of body mass. Total joint work was significantly affected by the additional load and CMJ phase. A significant interaction effect of additional load and CMJ phase was found for ankle and knee joint work. Joint work ratio was significantly affected by load in the knee and hip joint. The braking proportion of the total joint work increased as additional load increased. The alterations in joint work and joint work ratio should be considered when prescribing loaded CMJ as training exercises in terms of changed training stimuli or interpreting performance parameters of CMJ with different load conditions

Measuring galaxy cluster masses with CMB lensing using a Maximum Likelihood estimator: Statistical and systematic error budgets for future experiments

We develop a Maximum Likelihood estimator (MLE) to measure the masses of galaxy clusters through the impact of gravitational lensing on the temperature and polarization anisotropies of the cosmic microwave background (CMB). We show that, at low noise levels in temperature, this optimal estimator outperforms the standard quadratic estimator by a factor of two. For polarization, we show that the Stokes Q/U maps can be used instead of the traditional E- and B-mode maps without losing information. We test and quantify the bias in the recovered lensing mass for a comprehensive list of potential systematic errors. Using realistic simulations, we examine the cluster mass uncertainties from CMB-cluster lensing as a function of an experiment's beam size and noise level. We predict the cluster mass uncertainties will be 3 - 6% for SPT-3G, AdvACT, and Simons Array experiments with 10,000 clusters and less than 1% for the CMB-S4 experiment with a sample containing 100,000 clusters. The mass constraints from CMB polarization are very sensitive to the experimental beam size and map noise level: for a factor of three reduction in either the beam size or noise level, the lensing signal-to-noise improves by roughly a factor of two.Comment: 28 pages, 5 figures: figs 2, 3 updated, references added: accepted for publication in JCA

Inhibiting the Thermal Gelation of Copolymer Stabilized Nonaqueous Dispersions and the Synthesis of Full Color PMMA Particles

Polymeric particle dispersions have numerous potential applications; currently one of the most relevant is their use as inks in electrophoretic displays. These colloidal particles are synthesized from the appropriate monomer using nonaqueous dispersion (NAD) polymerization in a nonpolar solvent, which requires a stabilizer to control particle size and morphology. We have previously reported the facile synthesis of poly(methyl methacrylate)-block-poly(octadecyl acrylate) (PMMA-b-PODA) by atom transfer radical polymerization (ATRP), and its use in the NAD polymerization of MMA in hexane/dodecane solvent mixtures. Here we report the synthesis of monodisperse PMMA particles in dodecane following a standard “industrial” procedure using these PMMA-b-PODA stabilizers. However, it was observed that the particle suspensions solidified when they were left at temperatures below ?18 °C yet redispersed upon being heated. Differential scanning calorimetry, dynamic light scattering, and rheological studies demonstrated that this thermoresponsive behavior was due to a liquid–gel transition occurring at 17.5 °C as a consequence of the upper critical solution temperature of PODA in dodecane being traversed. Consequently, new copolymers were synthesized by ATRP with an ethylhexyl acrylate (EHA) co-monomer incorporated into the lyophilic (dodecane compatible) block. Dispersions stabilized by these PMMA-b-P(ODA-co-EHA) polymers with high EHA contents exhibited lower gelation temperatures because of the greater solvent compatibility with dodecane. The use of a PMMA65-b-(ODA10-co-EHA45) copolymer stabilizer (with the highest EHA content) gave PMMA dispersions that showed no gelation down to 4 °C and monodisperse cross-linked PMMA particles containing organic dyes (cyan, magenta, red, and black) giving colored particles across the size range of approximately 100–1300 nm

Adding some Dirt to Clean energy: Applying clay nanocomposites in solar cells

Polymer clay nanocomposite (PCN) thin films have found application across a number of applications, ranging from oxygen barriers to flame retardants, where their resistance to molecular gas diffusion has proven remarkably effective, even in films only a few hundred nanometers thick. Deposited using a layer-by-layer processing approach that takes advantage of self-assembly of the constituent components, these composite thin films comprise highly organized, alternating molecular layers of functional polymers and exfoliated clay platelets, commonly montmorillonite or vermiculite. Here, we explore the potential application and utility of PCN thin films in solar cells, where they serve as conformal, transparent barrier films with the potential to impact solar cell lifetime, reliability, and safety. Solar cell failures commonly result when environmental moisture and corrosive or reactive gases penetrate a cell’s encapsulant. Moreover, such cell degradation can manifest as a gradual decline in solar cell performance or, in the case when degradation leads to significantly damaged electrical elements, much more dramatic arc-faults that can lead to complete and dramatic module failure, even igniting module fires. Here, we describe how the unique nanostructure, materials chemistry, and gas barrier properties of PCNs offer promise toward addressing these challenges. Applying the PCN coatings to various elements of a solar cell module, we demonstrate the efficacy of PCNs as gas barriers, corrosion inhibitors, and arc-fault flammability mitigators. I will discuss here not only the results of our studies but also potential mechanisms for effective PCN function and present some apparent limitations of select approaches to PCN integration. These results reveal significant potential for PCNs to impact photovoltaic and other energy-related technologies, and our work highlights how these diverse, highly functional thin films may offer tremendous new opportunities for other next generation materials advances. Please click Additional Files below to see the full abstract