1,196 research outputs found

    On big rip singularities

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    In this comment we discuss big rip singularities occurring in typical phantom models by violation of the weak energy condition. After that, we compare them with future late-time singularities arising in models where the scale factor ends in a constant value and there is no violation of the strong energy condition. In phantom models the equation of state is well defined along the whole evolution, even at the big rip. However, both the pressure and the energy density of the phantom field diverge. In contrast, in the second kind of model the equation of state is not defined at the big rip because the pressure bursts at a finite value of the energy density.Comment: 8 page

    Nonlocal effects in high energy charged particle beams

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    Within the framework of the thermal wave model, an investigation is made of the longitudinal dynamics of high energy charged particle beams. The model includes the self-consistent interaction between the beam and its surroundings in terms of a nonlinear coupling impedance, and when resistive as well as reactive parts are included, the evolution equation becomes a generalised nonlinear Schroedinger equation including a nonlocal nonlinear term. The consequences of the resistive part on the propagation of particle bunches are examined using analytical as well as numerical methods.Comment: 6 pages, 6 figures, uses RevTeX

    Market incentives for shark fisheries

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    Fishers tend to prioritize landings of the most valuable product to better utilize vessel capacity. This may lead to discards of catches that are economically undesirable or legally prohibited. The high-value of shark fins and the low-value of shark carcasses has traditionally led to an example of that practice, known as finning. Brazil is an important player in the trade for non-fin shark products. The recent increase in shark meat trade is associated with increased imports of shark meat in Brazil. This increase may be a consequence of stricter finning regulations that has created incentives for full utilization of sharks and exposed the resource to a new source of demand. Thus, sharks overexploitation may increase, even if demand for fins weakens over time. This paper investigates the shark meat market development in Brazil over the last decades using demand and cointegration analysis, with a focus on before and after implementation of finning restrictions in 1998. Results indicate that shark meat is not a new market in Brazil, but an old one driven by a particular interest from local consumers. The decline in domestic shark meat landings, increasing demand for seafood, and the commoditization of shark meat have facilitated import growth. Additionally, domestic prices seem to influence imports most likely because Brazil is an important player as a shark meat consumer. This means that even with the global shark fin market weakening, the Brazilian demand for shark meat is likely to contribute to the overexploitation of sharks in poorly managed fisheries.publishedVersio

    Nursing Roles and Strategies in End-of-Life Decision Making in Acute Care: A Systematic Review of the Literature

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    The objective of this paper is to analyze the literature concerning nurses' roles and strategies in EOL decision making in acute care environments, synthesize the findings, and identify implications for future research. We conducted searches in CINAHL and PubMed, using a broad range of terms. The 44 articles retained for review had quantitative and qualitative designs and represented ten countries. These articles were entered into a matrix to facilitate examining patterns, themes, and relationships across studies. Three nursing roles emerged from the synthesis of the literature: information broker, supporter, and advocate, each with a set of strategies nurses use to enact the roles. Empirical evidence linking these nursing roles and strategies to patients and family members outcomes is lacking. Understanding how these strategies and activities are effective in helping patients and families make EOL decisions is an area for future research

    Cortical Network for Gaze Control in Humans Revealed Using Multimodal MRI

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    Functional magnetic resonance imaging (fMRI) techniques allow definition of cortical nodes that are presumed to be components of large-scale distributed brain networks involved in cognitive processes. However, very few investigations examine whether such functionally defined areas are in fact structurally connected. Here, we used combined fMRI and diffusion MRI-based tractography to define the cortical network involved in saccadic eye movement control in humans. The results of this multimodal imaging approach demonstrate white matter pathways connecting the frontal eye fields and supplementary eye fields, consistent with the known connectivity of these regions in macaque monkeys. Importantly, however, these connections appeared to be more prominent in the right hemisphere of humans. In addition, there was evidence of a dorsal frontoparietal pathway connecting the frontal eye field and the inferior parietal lobe, also right hemisphere dominant, consistent with specialization of the right hemisphere for directed attention in humans. These findings demonstrate the utility and potential of using multimodal imaging techniques to define large-scale distributed brain networks, including those that demonstrate known hemispheric asymmetries in human

    The “invisible caregiver”: multicaregiving among diabetic African-American grandmothers

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    To explore the multicaregiving roles African American grandmothers assume while self-managing their diabetes

    Penicillin Use in Meningococcal Disease Management: Active Bacterial Core Surveillance Sites, 2009.

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    In 2009, in the Active Bacterial Core surveillance sites, penicillin was not commonly used to treat meningococcal disease. This is likely because of inconsistent availability of antimicrobial susceptibility testing and ease of use of third-generation cephalosporins. Consideration of current practices may inform future meningococcal disease management guidelines

    Long-term effects of the Active for Life Year 5 (AFLY5) school-based cluster randomised controlled trial

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    Objective: To investigate the long-term effectiveness of a school-based intervention to improve physical activity and diet in children. Design: Cluster-randomised controlled trial. Setting: 60 primary schools in the southwest of England. Participants: Primary school children who were aged 8-9 years at recruitment, 9-10 years during the intervention and 10-11 years at the long-term follow-up assessment. Intervention: Teacher training, provision of lesson and child-parent interactive homework plans and teaching materials. Main Outcome Measures: Primary outcomes were accelerometer-assessed minutes of moderate to vigorous physical activity (MVPA) per day, accelerometer-assessed minutes of sedentary behaviour per day and reported daily consumption of servings of fruit and vegetables. Results: 60 schools with 2221 eligible children were recruited. As in the previously published assessment immediately after the end of the intervention, none of the three primary outcomes differed between children in schools allocated to the intervention, compared with those in control schools at the end of the long-term follow-up (1 year after the end of the intervention). Differences in secondary outcomes were consistent with those at the immediate follow-up, with no evidence that these had diminished over time. Comparing intervention with control schools, the difference in mean child-reported screen viewing at the weekend was -16.03 min (95% CI -32.82 to 0.73), for servings of snacks per day, the difference was -0.11 (95% CI -0.39 to 0.06), in servings of high-energy drinks per day -0.20 (95% CI -0.39 to -0.01) and in servings of high-fat foods per day -0.12 (95% CI -0.39 to 0.00). None of these reached our predefined level of statistical significance, especially after accounting for multiple testing. Conclusions: School-based curriculum interventions alone are unlikely to have a major public health impact on children's diet and physical activity.Emma L Anderson, Laura D Howe, Ruth R Kipping, Rona Campbell, Russell Jago, Sian M Noble, Sian Wells, Catherine Chittleborough, Tim J Peters, Debbie A Lawlo
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