294 research outputs found

    Nonlinear electromagnetic wave equations for superdense magnetized plasmas

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    By using the quantum hydrodynamic and Maxwell equations, we derive the generalized nonlinear electron magnetohydrodynamic, the generalized nonlinear Hall-MHD (HMHD), and the generalized nonlinear dust HMHD equations in a self-gravitating dense magnetoplasma. Our nonlinear equations include the self-gravitating, the electromagnetic, the quantum statistical electron pressure, as well as the quantum electron tunneling and electron spin forces. They are useful for investigating a number of wave phenomena including linear and nonlinear electromagnetic waves, as well as three-dimensional electromagnetic wave turbulence spectra and structures arising from mode coupling processes at nanoscales in dense quantum magnetoplasmas

    Using network centrality measures to manage landscape connectivity

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    We use a graph-theoretical landscape modeling approach to investigate how to identify central patches in the landscape as well as how these central patches influence (1) organism movement within the local neighborhood, and (2) the dispersal of organisms beyond the local neighborhood. Organism movements were theoretically estimated based on the spatial configuration of the habitat patches in the studied landscape. We find that centrality depends on the way the graph-theoretical model of habitat patches is constructed, although even the simplest network representation, not taking strength and directionality of potential organisms flows into account, still provides a coarse-grained assessment of the most important patches according to their contribution to landscape connectivity. Moreover, we identify (at least) two general classes of centrality. One accounts for the local flow of organisms in the neighborhood of a patch and the other for the ability to maintain connectivity beyond the scale of the local neighborhood. Finally, we study how habitat patches with high scores on different network centrality measures are distributed in a fragmented agricultural landscape in Madagascar. Results show that patches with high degree-, and betweenness centrality are widely spread, while patches with high subgraph- and closeness centrality are clumped together in dense clusters. This finding may enable multi-species analyses of single-species network models

    Surveillance of compliance with tobacco regulations in Örebro County, Sweden: a mixed methods study after the ban of test purchases

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    <p>Abstract</p> <p>Background</p> <p>Tobacco has long been known to be one of the most common reasons for sickness and premature deaths in the world. An important aspect of tobacco use is the youth's access to tobacco, and surveillance visits are one way to make sure how retailers are complying with age limit in the tobacco law. In Örebro County, Sweden, a project to reinforce the tobacco legislation was carried out in 2009-2010. One part of the project was surveillance visits that were done according to three different themes, called thematic surveillance.</p> <p>Methods</p> <p>This study is an evaluation of the results from thematic surveillance and has a mixed methods approach. The quantitative analyses concerns protocols from 217 surveillance visits, where questions were asked about three themes (self-monitoring programs; marketing; labeling of products and pricing). In addition, questionnaires filled out by six tobacco administrators who worked within the project were analyzed qualitatively by content analysis in order to study their perceptions and opinions of the project.</p> <p>Results</p> <p>This study shows that half of the visited retailers had self-monitoring programs. Lack of self-monitoring programs was significantly more common in smaller stores/kiosks and at restaurants. Further, the tobacco administrators who worked within the project perceived thematic surveillance as a good method for accomplishing better structure in surveillance work, but not as effective as purchase attempts (mystery shopping).</p> <p>Conclusions</p> <p>Thematic surveillance was perceived as positive and the method was also regarded to be a good way to work with surveillance. However, the method could be developed further for optimal use and better effect at the retailers. It is clear that people who work with tobacco prevention at the local level in Örebro County want to use purchase attempts as a surveillance method, and that they believe that purchase attempts is the best way to make sure if store comply with the tobacco law.</p

    Genetic Variation in Glutathione-Related Genes and Body Burden of Methylmercury

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    BACKGROUND: Exposure to toxic methylmercury (MeHg) through fish consumption is a large problem worldwide, and it has led to governmental recommendations of reduced fish consumption and blacklisting of mercury-contaminated fish. The elimination kinetics of MeHg varies greatly among individuals. Knowledge about the reasons for such variation is of importance for improving the risk assessment for MeHg. One possible explanation is hereditary differences in MeHg metabolism. MeHg is eliminated from the body as a glutathione (GSH) conjugate. OBJECTIVES: We conducted this study to assess the influence of polymorphisms in GSH-synthesizing [glutamyl-cysteine ligase modifier subunit (GCLM-588) and glutamyl-cysteine ligase catalytic subunit (GCLC-129)] or GSH-conjugating [glutathione S-transferase pi 1 (GSTP1-105 and GSTP1-114)] genes on MeHg retention. METHODS: Based on information obtained from questionnaires, 292 subjects from northern Sweden had a high consumption of fish (lean/fat fish two to three times per week or more). We measured total Hg in erythrocytes (Ery-Hg) and long-chain n-3 polyunsaturated fatty acids in plasma (P-PUFA; an exposure marker for fish intake). RESULTS: The GSTP1 genotype modified Ery-Hg; effects were seen for GSTP1-105 and -114 separately, and combining them resulted in stronger effects. We found evidence of effect modification: individuals with zero or one variant allele demonstrated a steeper regression slope for Ery-Hg (p = 0.038) compared with individuals with two or more variant alleles. The GCLM-588 genotype also influenced Ery-Hg (p = 0.035): Individuals with the GCLM-588 TT genotype demonstrated the highest Ery-Hg, but we saw no evidence of effect modification with increasing P-PUFA. CONCLUSIONS: These results suggest a role of GSH-related polymorphisms in MeHg metabolism

    Patients' independence of a nurse for the administration of subcutaneous anti-TNF therapy: A phenomenographic study

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    Rheumatology nursing supports patients to manage their lives and live as independently as possible without pain, stiffness and functional restrictions. When conventional drugs fail to delay the development of the rheumatic disease, the patient may require biological treatment such as self-administered subcutaneous anti-tumour necrosis factor (TNF) therapy. It is therefore important that the patient perspective focuses on the life-changing situation caused by the administration of regular subcutaneous injections. The aim of this study was to describe variations in how patients with rheumatic diseases experience their independence of a nurse for administration of subcutaneous anti-TNF therapy. The study had a descriptive, qualitative design with a phenomenographic approach and was carried out by means of 20 interviews. Four ways of understanding the patients' experience of their subcutaneous anti-TNF therapy and independence of a nurse emerged: the struggling patient; the learning patient; the participating patient; the independent patient. Achieving independence of a nurse for subcutaneous anti-TNF injections can be understood by the patients in different ways. In their strive for independence, patients progress by learning about and participating in drug treatment, after which they experience that the injections make them independent
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