5,165 research outputs found

    The large-scale axisymmetric magnetic topology of avery-low-mass fully-convective star

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    Understanding how cool stars produce magnetic fields within their interiors is crucial for predicting the impact of such fields, such as the activity cycle of the Sun. In this respect, studying fully convective stars enables us to investigate the role of convective zones in magnetic field generation. We produced a magnetic map of a rapidly rotating, very-low-mass, fully convective dwarf through tomographic imaging from time series of spectropolarimetric data. Our results, which demonstrate that fully convective stars are able to trigger axisymmetric large-scale poloidal fields without differential rotation, challenge existing theoretical models of field generation in cool stars.Comment: 17 pages, 4 figures, supplementary online material (including 2 figures

    A supersonic crowdion in mica: Ultradiscrete kinks with energy between 40^{40}K recoil and transmission sputtering

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    In this chapter we analyze in detail the behaviour and properties of the kinks found in an one dimensional model for the close packed rows of potassium ions in mica muscovite. The model includes realistic potentials obtained from the physics of the problem, ion bombardment experiments and molecular dynamics fitted to experiments. These kinks are supersonic and have an unique velocity and energy. They are ultradiscrete involving the translation of an interstitial ion, which is the reason they are called 'crowdions'. Their energy is below the most probable source of energy, the decay of the 40^{40}K isotope and above the energy needed to eject an atom from the mineral, a phenomenon that has been observed experimentallyComment: 28 pages, 15 figure

    Holocene lake sediment core sequences from Lochnagar, Cairngorm Mts., Scotland - UK final report for CHILL-10,000

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    The CHILL 10,000 research objective at Lochnagar is to examine proxy data for temperature and climate conditions. Changes in lake sediment stratigraphical data can be used to reconstruct past conditions. These proxies include organic and minerogenic matter as a bulk proxy for catchment and within-lake productivity, chironomids as a proxy for air temperature, diatoms as an indicator for lake water pH, pollen as an indicator of catchment vegetation and finally biomarkers to help determine changes in proportions of organic source material within the lake mud

    Acute Intrathoracic Gastric Volvulus due to Diaphragmatic Hernia: A Rare Emergency Easily Overlooked

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    Acute intrathoracic gastric volvulus occurs when the stomach undergoes organoaxial torsion in the chest due to either concomitant enlargement of the hiatus or a diaphragmatic hernia. Iatrogenic diaphragmatic hernia can occur after hiatal hernia repair and other surgical procedures, such as nephrectomy, esophagogastrectomy and splenopancreatectomy. We describe a 49-year-old woman who presented to our emergency department with acute moderate epigastric soreness and vomiting. She had undergone extensive gynecologic surgery including splenectomy 1 year before. The chest radiograph obtained in the emergency department demonstrated an elevated gastric air-fluid level in the left lower lung field. An urgent gastroscopy showed twisted structural abnormality of the stomach body. A computed tomography scan demonstrated the distended stomach, located in the left lower hemithorax through a left diaphragmatic defect. Emergent transthoracic repair was performed. Postoperative recovery was uneventful, and the patient did not experience any pain or difficulty with eating

    Globalization, the ambivalence of European integration and the possibilities for a post-disciplinary EU studies

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    Using the work of Manuel Castells as a starting point, this article explores the ambivalent relationship between globalization and European integration and the variety of ways in which the mainstream political science of the EU has attempted to deal with this issue. The analysis here suggests that various 'mainstreaming' disciplinary norms induce types of work that fail to address fully the somewhat paradoxical and counter-intuitive range of possible relationships between globalization and European integration. The article explores critically four possible analytical ways out of this paradox—abandonment of the concept of globalization, the development of definition precision in globalization studies, the reorientation of work to focus on globalization as discourse, and inter- and post-disciplinarity. The argument suggests that orthodox discussions of the relationship require a notion of social geography that sits at odds with much of the literature on globalization and while greater dialogue between disciplines is to be welcomed, a series of profound epistemological questions need to be confronted if studies of the interplay between global and social process are to be liberated from their disciplinary chains

    Chemokine control of HIV-1 infection: Beyond a binding competition

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    A recent paper by Cameron et al. demonstrated that certain chemokines such as CCL19 activate cofilin and actin dynamics, promoting HIV nuclear localization and integration into resting CD4 T cells. Apparently, these chomokines synergize with the viral envelope protein, triggering cofilin and actin dynamics necessary for the establishment of viral latency. This study opens a new avenue for understanding chemokine interaction with HIV. Traditionally, chemokine control of HIV infection focuses on competitive binding and down-modulation of the corecptors, particularly CCR5. This new study suggests that a diverse group of chemokines may also affect HIV infection through synergistic or antagonistic interaction with the viral coreceptor signaling pathways

    Surveillance strategies for Classical Swine Fever in wild boar – a comprehensive evaluation study to ensure powerful surveillance

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    Surveillance of Classical Swine Fever (CSF) should not only focus on livestock, but must also include wild boar. To prevent disease transmission into commercial pig herds, it is therefore vital to have knowledge about the disease status in wild boar. In the present study, we performed a comprehensive evaluation of alternative surveillance strategies for Classical Swine Fever (CSF) in wild boar and compared them with the currently implemented conventional approach. The evaluation protocol was designed using the EVA tool, a decision support tool to help in the development of an economic and epidemiological evaluation protocol for surveillance. To evaluate the effectiveness of the surveillance strategies, we investigated their sensitivity and timeliness. Acceptability was analysed and finally, the cost-effectiveness of the surveillance strategies was determined. We developed 69 surveillance strategies for comparative evaluation between the existing approach and the novel proposed strategies. Sampling only within sub-adults resulted in a better acceptability and timeliness than the currently implemented strategy. Strategies that were completely based on passive surveillance performance did not achieve the desired detection probability of 95%. In conclusion, the results of the study suggest that risk-based approaches can be an option to design more effective CSF surveillance strategies in wild boar

    Divergent mathematical treatments in utility theory

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    In this paper I study how divergent mathematical treatments affect mathematical modelling, with a special focus on utility theory. In particular I examine recent work on the ranking of information states and the discounting of future utilities, in order to show how, by replacing the standard analytical treatment of the models involved with one based on the framework of Nonstandard Analysis, diametrically opposite results are obtained. In both cases, the choice between the standard and nonstandard treatment amounts to a selection of set-theoretical parameters that cannot be made on purely empirical grounds. The analysis of this phenomenon gives rise to a simple logical account of the relativity of impossibility theorems in economic theory, which concludes the paper
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