1,266 research outputs found

    Children’s experiences of domestic violence: A teaching and training challenge

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    In this chapter we explore the complexities of training and teaching students and practitioners about children’s experiences of domestic violence. The research conducted on children’s experiences has tended to focus on these negative outcomes, representing these children as damaged and vulnerable (Callaghan and Alexander, 2015; Øverlien, 2013). Such research outlines that children have elevated lifelong risk of mental health difficulties (Bogat et al., 2006; Lamers-Winkelman et al., 2012; Stover, 2005); interpersonal difficulties (Baldry, 2003; Holmes, 2013; Renner and Slack, 2006); educational difficulties and educational drop out (Byrne and Taylor, 2007), and physical health problems (Bair-Merritt et al., 2006). Despite this research representation of children as vulnerable and damaged, services for children who experience domestic violence are often underdeveloped and underfunded (Statham, 2004; Willis et al., 2010), typically additional to adult domestic abuse services, for instance as part of the services offered in shelters

    Non-linear Response of the trap model in the aging regime : Exact results in the strong disorder limit

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    We study the dynamics of the one dimensional disordered trap model presenting a broad distribution of trapping times p(τ)∼1/τ1+μp(\tau) \sim 1/\tau^{1+\mu}, when an external force is applied from the very beginning at t=0t=0, or only after a waiting time twt_w, in the linear as well as in the non-linear response regime. Using a real-space renormalization procedure that becomes exact in the limit of strong disorder μ→0\mu \to 0, we obtain explicit results for many observables, such as the diffusion front, the mean position, the thermal width, the localization parameters and the two-particle correlation function. In particular, the scaling functions for these observables give access to the complete interpolation between the unbiased case and the directed case. Finally, we discuss in details the various regimes that exist for the averaged position in terms of the two times and the external field.Comment: 27 pages, 1 eps figur

    Polarons with a twist

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    We consider a polaron model where molecular \emph{rotations} are important. Here, the usual hopping between neighboring sites is affected directly by the electron-phonon interaction via a {\em twist-dependent} hopping amplitude. This model may be of relevance for electronic transport in complex molecules and polymers with torsional degrees of freedom, such as DNA, as well as in molecular electronics experiments where molecular twist motion is significant. We use a tight-binding representation and find that very different polaronic properties are already exhibited by a two-site model -- these are due to the nonlinearity of the restoring force of the twist excitations, and of the electron-phonon interaction in the model. In the adiabatic regime, where electrons move in a {\em low}-frequency field of twisting-phonons, the effective splitting of the energy levels increases with coupling strength. The bandwidth in a long chain shows a power-law suppression with coupling, unlike the typical exponential dependence due to linear phonons.Comment: revtex4 source and one eps figur

    Low Reynolds number hydrodynamics of asymmetric, oscillating dumbbell pairs

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    Active dumbbell suspensions constitute one of the simplest model system for collective swimming at low Reynolds number. Generalizing recent work, we derive and analyze stroke-averaged equations of motion that capture the effective hydrodynamic far-field interaction between two oscillating, asymmetric dumbbells in three space dimensions. Time-averaged equations of motion, as those presented in this paper, not only yield a considerable speed-up in numerical simulations, they may also serve as a starting point when deriving continuum equations for the macroscopic dynamics of multi-swimmer suspensions. The specific model discussed here appears to be particularly useful in this context, since it allows one to investigate how the collective macroscopic behavior is affected by changes in the microscopic symmetry of individual swimmers.Comment: 10 pages, to appear in EPJ Special Topic

    Spin Dependent Fragmentation Functions for Heavy Flavor Baryons and Single Heavy Hyperon Polarization

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    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. Λb\Lambda_b , Λc\Lambda_c and Ξc\Xi_c production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted Λc\Lambda_c polarization is roughly in agreement with experiment.Comment: LaTeX2e 11 pages with 4 PostScript figures. To be published in Proceedings of the International Workshop ``Symmetries and spin'', Praha-SPIN-200

    Variable response of nirK and nirS containing denitrifier communities to long term pH manipulation and cultivation

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    Denitrification is a key process responsible for the majority of soil nitrous oxide (N2O) emissions but the influences of pH and cultivation on the soil denitrifier community remain poorly understood. We hypothesised that the abundance and community structure of the total bacterial community and bacterial denitrifiers would be pH sensitive and that nirK and nirS containing denitrifiers would differ in their responses to change in pH and cultivation. We investigated the effect of long-term pH adjusted soils (ranging from pH 4.2 to pH 6.6) under different lengths of grass cultivation (one, two and three years of ley grass) on the general bacterial and denitrifier functional communities using 16S rRNA, nirK and nirS genes as markers. Denitrifier abundance increased with pH, and at pH below 4.7 there was a greater loss in nirS abundance per unit drop in pH than soils above this threshold pH. All community structures responded to changes in soil pH whilst cultivation only influenced the community structure of nirK. These differences in denitrifier responses highlight the importance of considering both nirK and nirS gene markers for estimating denitrifier activity. Identifying such thresholds in response of the microbial community to changes in pH is essential to understanding impacts of management or environmental change

    Bacterial species from retailed poultry eggs in Tshwane, South Africa : implication for consumers

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    Food safety is an important public health issue and governments across the world are intensifying their efforts to improve the quantity, quality and the safety of national food supplies. Bacteria, especially Salmonella species, present in or on chicken meat and hens’ eggs in particular are the most common causes of food poisoning and the major sources of human salmonellosis. Literature reveals little information on the risk factors for salmonellae infection in Africa. The aim of this study was to determine which, if any, bacteria, especially Salmonella species, are present in and on hens’ eggs. Representative bacterial colonies were confirmed with Gram staining and then identified using the MALDI-TOF Biotyper assay. The genera identified were Escherichia coli (34%), Enterococcus faecalis (14%), Proteus mirabilis (9%), Klebshiella pneumoniae (7%), Salmonella Typhimurium (6%), Enterobacter cloacae (1%), Stenotrophomonas maltophilia (0.6%), Salmonella Dublin (0.6%) and Salmonella Braenderup (0.2%). Raw hens’ eggs and products containing raw hens’ eggs may contain pathogenic bacteria, thereby exposing a large number of consumers to the risk of contracting food poisoning when undercooked or uncooked hens’ eggs are consumed. SIGNIFICANCE : • Enterobacteriaceae counts are used as an indicator to evaluate the hygienic quality of food. • The presence of Salmonella species and other Enterobacteriaceae in raw hens’ eggs poses a health risk to consumers. • Any product in which raw eggs are used must be provided with a conspicuous label stating that it may contain pathogenic bacteria.Funding of the project was through the research funds of F.S.B. and E.M.B.http://www.sajs.co.zaam2018Food ScienceParaclinical Science

    Cosmology of the Lifshitz universe

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    We study the ultraviolet complete non-relativistic theory recently proposed by Horava. After introducing a Lifshitz scalar for a general background, we analyze the cosmology of the model in Lorentzian and Euclidean signature. Vacuum solutions are found and it is argued the existence of non-singular bouncing profiles. We find a general qualitative agreement with both the picture of Causal Dynamical Triangulations and Quantum Einstein Gravity. However, inflation driven by a Lifshitz scalar field on a classical background might not produce a scale-invariant spectrum when the principle of detailed balance is assumed.Comment: 23 pages. v2: one reference and one equation added, main conclusions unchanged; v3: matches published version, discussion improved, typos correcte

    Anomalous diffusion, Localization, Aging and Sub-aging effects in trap models at very low temperature

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    We study in details the dynamics of the one dimensional symmetric trap model, via a real-space renormalization procedure which becomes exact in the limit of zero temperature. In this limit, the diffusion front in each sample consists in two delta peaks, which are completely out of equilibrium with each other. The statistics of the positions and weights of these delta peaks over the samples allows to obtain explicit results for all observables in the limit T→0T \to 0. We first compute disorder averages of one-time observables, such as the diffusion front, the thermal width, the localization parameters, the two-particle correlation function, and the generating function of thermal cumulants of the position. We then study aging and sub-aging effects : our approach reproduces very simply the two different aging exponents and yields explicit forms for scaling functions of the various two-time correlations. We also extend the RSRG method to include systematic corrections to the previous zero temperature procedure via a series expansion in TT. We then consider the generalized trap model with parameter α∈[0,1]\alpha \in [0,1] and obtain that the large scale effective model at low temperature does not depend on α\alpha in any dimension, so that the only observables sensitive to α\alpha are those that measure the `local persistence', such as the probability to remain exactly in the same trap during a time interval. Finally, we extend our approach at a scaling level for the trap model in d=2d=2 and obtain the two relevant time scales for aging properties.Comment: 33 pages, 3 eps figure
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