1,533 research outputs found

    Transformation textures in post-perovskite: Understanding mantle flow in the D '' layer of the Earth

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    Deformation and texture formation in (Mg, Fe)SiO3 post perovskite (ppv) is a potential explanation for the strong seismic anisotropy that is found in the D '' layer of the Earth. However, different experimental approaches have resulted in different lattice preferred orientations (LPO) in deformed ppv that have led to ambiguity in the interpretation of deformation in the lowermost mantle. Here, we show that deformation of the analogue substance CaIrO3 during a phase transformation from perovskite to ppv leads to a transformation texture that differs from the CaIrO3 ppv deformation texture but resembles the results from ppv deformation experiments in diamond anvil cells. Assuming material spreading parallel to the core-mantle boundary, our results predict a widespread shear wave splitting with fast horizontal S-waves, which is compatible with seismic studies. Downwelling material that undergoes a phase transformation may develop a transformation texture that would locally result in vertically polarized fast S-waves. Citation: Walte, N. P., F. Heidelbach, N. Miyajima, D. J. Frost, D. C. Rubie, and D. P. Dobson (2009), Transformation textures in post-perovskite: Understanding mantle flow in the D '' layer of the Earth, Geophys. Res. Lett., 36, L04302, doi: 10.1029/2008GL036840

    An integrated groupwork methodology for working with sex offenders

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    There is now a considerable literature on the assessment and treatment of sexual offenders. There exists another substantial literature on therapeutic groupwork and its relevance to a range of clinical populations. These bodies of work have made reference to the other in terms of their mutual relevance. However, there has been no comprehensive attempt to apply groupwork theory and principles systematically to work with sex offenders. While this work is generally carried out using a group format and the application of groupwork principles is enthusiastically promoted in the field, the application is underdeveloped both empirically and even more so conceptually. As a result, practices vary greatly. We argue here that a systematic and integrated consideration of the application of groupwork methodology to the treatment of sex offenders has the potential to significantly enhance treatment effectiveness. We conclude with implications for training and clinical practice

    Quantitative characterization of plastic deformation of single diamond crystals: A high pressure high temperature (HPHT) experimental deformation study combined with electron backscatter diffraction (EBSD)

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    We report the results of a high-pressure high-temperature (HPHT) experimental investigation into the deformation of diamonds using the D-DIA apparatus. Electron backscatter diffraction (EBSD) data confirm that well-defined 300–700 nm wide {111} slip lamellae are in fact deformation micro-twins with a 60° rotation around a axis. Such twins formed at high confining pressures even without any apparatus-induced differential stress; mechanical anisotropy within the cell assembly was sufficient for their formation with very little subsequent lattice bending ( slip system dominates as expected for the face-centred cubic (FCC) structure of diamond. Slip occurs on multiple {111} planes resulting in rotation around axes. Deformation microstructure characteristics depend on the orientation of the principal stress axes and finite strain but are independent of confining pressure and nitrogen content. All of the uniaxially deformed samples took on a brown colour, irrespective of their initial nitrogen characteristics. This is in contrast to the two quasi-hydrostatic experiments, which retained their original colour (colourless for nitrogen free diamond, yellow for single substitutional nitrogen, Type Ib diamond) despite the formation of {111} twin lamellae. Comparison of our experimental data with those from two natural brown diamonds from Finsch mine (South Africa) shows the same activation of the dominant slip system. However, no deformation twin lamellae are present in the natural samples. This difference may be due to the lower strain rates experienced by the natural samples investigated. Our study shows the applicability and potential of this type of analysis to the investigation of plastic deformation of diamonds under mantle conditions

    Using Bayesian mark-recapture modelling to quantify the strength and duration of post-release effects in reintroduced populations

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    Translocated animals often suffer elevated mortality during some acclimation period after release. Such post-release effects must be accounted for when estimating normal survival rates and therefore predicting population persistence. The standard approach for doing this is to nominate a fixed acclimation period, and either i) exclude survival data over that period, or ii) use model selection criteria to test whether survival differs over that period. We present a more flexible approach where the acclimation period is treated as unknown and is estimated simultaneously with the pre- and post-acclimation survival probabilities. We illustrate this approach using survival data for six reintroduced populations involving three New Zealand forest bird species. Analyses of the complete data sets (22–73 surveys conducted over 4–14 years) indicated that significant post-release effects occurred in at least one sex in five of the six populations, with 30–84% mortality attributable to post-release effects over acclimation periods ranging from 1 to 9 months. When we applied the approach to just the first year of data for each population, the estimated normal survival rates were consistent with those obtained from the complete data sets, and always at least as accurate as our previous approach of excluding data up to the next breeding season after translocation. The flexible approach therefore appears to be effective for accounting for post-release effects in survival estimation, and is beneficial in quantifying both the strength and duration of those effects so that pre- and post-release management strategies are better informed

    What lies beneath: exploring links between asylum policy and hate crime in the UK

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    This paper explores the link between increasing incidents of hate crime and the asylum policy of successive British governments with its central emphasis on deterrence. The constant problematisation of asylum seekers in the media and political discourse ensures that 'anti-immigrant' prejudice becomes mainstr earned as a common-sense response. The victims are not only the asylum seekers hoping for a better life but democratic society itself with its inherent values of pluralism and tolerance debased and destabilised

    Family Planning Decisions, Perceptions and Gender Dynamics among Couples in Mwanza, Tanzania: A Qualitative Study.

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    Contraceptive use is low in developing countries which are still largely driven by male dominated culture and patriarchal values. This study explored family planning (FP) decisions, perceptions and gender dynamics among couples in Mwanza region of Tanzania. Twelve focus group discussions and six in-depth interviews were used to collect information from married or cohabiting males and females aged 18-49. The participants were purposively selected. Qualitative methods were used to explore family planning decisions, perceptions and gender dynamics among couples. A guide with questions related to family planning perceptions, decisions and gender dynamics was used. The discussions and interviews were tape-recorded, transcribed verbatim and analyzed manually and subjected to content analysis. Four themes emerged during the study. First, "risks and costs" which refer to the side effects of FP methods and the treatment of side -effects as well as the costs inherit in being labeled as an unfaithful spouse. Second, "male involvement" as men showed little interest in participating in family planning issues. However, the same men were mentioned as key decision-makers even on the number of children a couple should have and the child spacing of these children. Third, "gender relations and communication" as participants indicated that few women participated in decision-making on family planning and the number of children to have. Fourth, "urban-rural differences", life in rural favoring having more children than urban areas therefore, the value of children depended on the place of residence. Family Planning programs should adapt the promotion of communication as well as joint decision-making on FP among couples as a strategy aimed at enhancing FP use

    Testing the cognitive-behavioural maintenance models across DSM-5 bulimic-type eating disorder diagnostic groups: A multi-centre study

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    The original cognitive-behavioural (CB) model of bulimia nervosa, which provided the basis for the widely used CB therapy, proposed that specific dysfunctional cognitions and behaviours maintain the disorder. However, amongst treatment completers, only 40–50 % have a full and lasting response. The enhanced CB model (CB-E), upon which the enhanced version of the CB treatment was based, extended the original approach by including four additional maintenance factors. This study evaluated and compared both CB models in a large clinical treatment seeking sample (N = 679), applying both DSM-IV and DSM-5 criteria for bulimic-type eating disorders. Application of the DSM-5 criteria reduced the number of cases of DSM-IV bulimic-type eating disorders not otherwise specified to 29.6 %. Structural equation modelling analysis indicated that (a) although both models provided a good fit to the data, the CB-E model accounted for a greater proportion of variance in eating-disordered behaviours than the original one, (b) interpersonal problems, clinical perfectionism and low self-esteem were indirectly associated with dietary restraint through over-evaluation of shape and weight, (c) interpersonal problems and mood intolerance were directly linked to binge eating, whereas restraint only indirectly affected binge eating through mood intolerance, suggesting that factors other than restraint may play a more critical role in the maintenance of binge eating. In terms of strength of the associations, differences across DSM-5 bulimic-type eating disorder diagnostic groups were not observed. The results are discussed with reference to theory and research, including neurobiological findings and recent hypotheses

    Serum immunoglobulin G, M and A response to Cryptosporidium parvum in Cryptosporidium-HIV co-infected patients

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    <p>Abstract</p> <p>Background</p> <p><it>Cryptosporidium parvum</it>, the protozoan parasite, causes a significant enteric disease in immunocompromised hosts such as HIV patients. The present study was aimed to compare serum IgG, IgM and IgA responses to crude soluble antigen of <it>C. parvum </it>in HIV seropositive and seronegative patients co-infected with <it>Cryptosporidium </it>and to correlate the responses with symptomatology.</p> <p>Methods</p> <p><it>Cryptosporidium parvum </it>specific serum antibody (IgG, IgM and IgA) responses were assessed by ELISA in 11 HIV seropositive <it>Cryptosporidium </it>positive (Group I), 20 HIV seropositive <it>Cryptosporidium </it>negative (Group II), 10 HIV seronegative <it>Cryptosporidium </it>positive (Group III), 20 HIV seronegative <it>Cryptosporidium </it>negative healthy individuals (Group IV) and 25 patients with other parasitic diseases (Group V).</p> <p>Results</p> <p>A positive IgG and IgA antibody response was observed in significantly higher number of <it>Cryptosporidium </it>infected individuals (Gp I and III) compared to <it>Cryptosporidium </it>un-infected individuals (Gp II, IV and V) irrespective of HIV/immune status. Sensitivity of IgG ELISA in our study was found to be higher as compared to IgM and IgA ELISA. The number of patients with positive IgG, IgM and IgA response was not significantly different in HIV seropositive <it>Cryptosporidium </it>positive patients with diarrhoea when compared to patients without diarrhoea and in patients with CD4 counts <200 when compared to patients with CD4 counts >200 cells/μl.</p> <p>Conclusion</p> <p>The study showed specific serum IgG and IgA production in patients infected with <it>Cryptosporidium</it>, both HIV seropositive and seronegative as compared to uninfected subjects suggesting induction of <it>Cryptosporidium </it>specific humoral immune response in infected subjects. However, there was no difference in number of patients with positive response in HIV seropositive or seronegative groups indicating that HIV status may not be playing significant role in modulation of <it>Cryptosporidium </it>specific antibody responses. The number of patients with positive IgG, IgM and IgA response was not significantly different in patients with or without history of diarrhoea thereby indicating that <it>Cryptosporidium </it>specific antibody responses may not be necessarily associated with protection from symptomatology.</p

    Survival trends for small intestinal cancer in England and Wales, 1971–1990: national population-based study

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    This population-based study examines prognostic factors and survival trends among adults (15–99 years) diagnosed with small intestinal cancer in England and Wales during 1971–1990 and followed up to 1995. During this period, the 1- and 5-year age-standardised relative survival rates for small intestinal cancers combined were 42% and 23%, respectively. Duodenal tumours, adenocarcinomas, men, patients with advanced age and the most deprived patients had the poorest prognosis. For all small bowel tumours combined, the excess risk of death fell significantly by 6–9% every 4 years over the 20-year period (adjusted excess hazard ratio (EHR) 0.91 at 1 year after diagnosis, 0.94 at 5 years). For duodenal tumours, the EHR fell by about 14% (95% CI 5–22%) every 4 years between 1979 and 1990, and a similar trend for jejunal tumours was of borderline significance. Further population-based investigations linking survival data to individual data on diagnostic methods and types of treatment are needed
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