2,198 research outputs found

    Conjugacy theorems for loop reductive group schemes and Lie algebras

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    The conjugacy of split Cartan subalgebras in the finite dimensional simple case (Chevalley) and in the symmetrizable Kac-Moody case (Peterson-Kac) are fundamental results of the theory of Lie algebras. Among the Kac-Moody Lie algebras the affine algebras stand out. This paper deals with the problem of conjugacy for a class of algebras --extended affine Lie algebras-- that are in a precise sense higher nullity analogues of the affine algebras. Unlike the methods used by Peterson-Kac, our approach is entirely cohomological and geometric. It is deeply rooted on the theory of reductive group schemes developed by Demazure and Grothendieck, and on the work of J. Tits on buildingsComment: Publi\'e dans Bulletin of Mathematical Sciences 4 (2014), 281-32

    Frequent use of paracetamol and risk of allergic disease among women in an Ethiopian population

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    Introduction The hypothesis that paracetamol might increase the risk of asthma and other allergic diseases have gained support from a range of independent studies. However, in studies based in developed countries, the possibility that paracetamol and asthma are associated through aspirin avoidance is difficult to exclude. Objectives To explore this hypothesis among women in a developing country, where we have previously reported aspirin avoidance to be rare. Methods In 2005/6 a population based cohort of 1065 pregnant women was established in Butajira, Ethiopia and baseline demographic data collected. At 3 years post birth, an interview-based questionnaire administered to 945 (94%) of these women collected data on asthma, eczema, and hay fever in the past 12 month, frequency of paracetamol use and potential confounders. Allergen skin tests to Dermatophagoides pteronyssinus and cockroach were also performed. The independent effects of paracetamol use on allergic outcomes were determined using multiple logistic regression analysis. Findings The prevalence of asthma, eczema and hay fever was 1.7%, 0.9% and 3.8% respectively; of any one of these conditions 5.5%, and of allergen sensitization 7.8%. Paracetamol use in the past month was reported by 29%, and associations of borderline significance were seen for eczema (adjusted OR (95% CI) = 8.51 (1.68 to 43.19) for 1–3 tablets and 2.19 (0.36 to 13.38) for ≥4 tablets, compared to no tablets in the past month; overall p = 0.055) and for ‘any allergic condition’ (adjusted OR (95% CI) = 2.73 (1.22 to 6.11) for 1–3 tablets and 1.35 (0.67 to 2.70) for ≥4 tablets compared to 0 in the past month; overall p = 0.071). Conclusions This study provides further cross-sectional evidence that paracetamol use increases the risk of allergic disease

    Associations of sedentary behaviour, physical activity, blood pressure and anthropometric measures with cardiorespiratory fitness in children with cerebral palsy

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    Background - Children with cerebral palsy (CP) have poor cardiorespiratory fitness in comparison to their peers with typical development, which may be due to low levels of physical activity. Poor cardiorespiratory fitness may contribute to increased cardiometabolic risk. Purpose - The aim of this study was to determine the association between sedentary behaviour, physical activity and cardiorespiratory fitness in children with CP. An objective was to determine the association between cardiorespiratory fitness, anthropometric measures and blood pressure in children with CP. Methods- This study included 55 ambulatory children with CP [mean (SD) age 11.3 (0.2) yr, range 6-17 yr; Gross Motor Function Classification System (GMFCS) levels I and II]. Anthropometric measures (BMI, waist circumference and waist-height ratio) and blood pressure were taken. Cardiorespiratory fitness was measured using a 10 m shuttle run test. Children were classified as low, middle and high fitness according to level achieved on the test using reference curves. Physical activity was measured by accelerometry over 7 days. In addition to total activity, time in sedentary behaviour and light, moderate, vigorous, and sustained moderate-to-vigorous activity (≥10 min bouts) were calculated. Results - Multiple regression analyses revealed that vigorous activity (β = 0.339, p<0.01), sustained moderate-to-vigorous activity (β = 0.250, p<0.05) and total activity (β = 0.238, p<0.05) were associated with level achieved on the shuttle run test after adjustment for age, sex and GMFCS level. Children with high fitness spent more time in vigorous activity than children with middle fitness (p<0.05). Shuttle run test level was negatively associated with BMI (r2 = -0.451, p<0.01), waist circumference (r2 = -0.560, p<0.001), waist-height ratio (r2 = -0.560, p<0.001) and systolic blood pressure (r2 = -0.306, p<0.05) after adjustment for age, sex and GMFCS level. Conclusions - Participation in physical activity, particularly at a vigorous intensity, is associated with high cardiorespiratory fitness in children with CP. Low cardiorespiratory fitness is associated with increased cardiometabolic risk

    Ecologic Niche Modeling of Blastomyces dermatitidis in Wisconsin

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    Background: Blastomycosis is a potentially fatal mycosis that is acquired by inhaling infectious spores of Blastomyces dermatitidis present in the environment. The ecology of this pathogen is poorly understood, in part because it has been extremely difficult to identify the niche(s) it occupies based on culture isolation of the organism from environmental samples. Methodology/Principal Findings: We investigated the ecology of blastomycosis by performing maximum entropy modeling of exposure sites from 156 cases of human and canine blastomycosis to provide a regional-scale perspective of the geographic and ecologic distribution of B. dermatitidis in Wisconsin. Based on analysis with climatic, topographic, surface reflectance and other environmental variables, we predicted that ecologic conditions favorable for maintaining the fungus in nature occur predominantly within northern counties and counties along the western shoreline of Lake Michigan. Areas of highest predicted occurrence were often in proximity to waterways, especially in northcentral Wisconsin, where incidence of infection is highest. Ecologic conditions suitable for B. dermatitidis are present in urban and rural environments, and may differ at the extremes of distribution of the species in the state. Conclusions/Significance: Our results provide a framework for a more informed search for specific environmental factors modulating B. dermatitidis occurrence and transmission and will be useful for improving public health awareness of relativ

    Pelvic actinomycosis presenting with a large abscess and bowel stenosis with marked response to conservative treatment: a case report

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    Pelvic actinomycosis is a rare disease that can result in abscess formation, bowel obstruction, and other serious complications. Moreover, the correct diagnosis can seldom be established before radical surgery because the disease often mimics pelvic neoplasms. It has been recently recognized that pelvic actinomycosis is associated with long-term use of an intrauterine contraceptive device

    Quantum nondemolition measurement of mechanical motion quanta

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    The fields of opto- and electromechanics have facilitated numerous advances in the areas of precision measurement and sensing, ultimately driving the studies of mechanical systems into the quantum regime. To date, however, the quantization of the mechanical motion and the associated quantum jumps between phonon states remains elusive. For optomechanical systems, the coupling to the environment was shown to preclude the detection of the mechanical mode occupation, unless strong single photon optomechanical coupling is achieved. Here, we propose and analyse an electromechanical setup, which allows to overcome this limitation and resolve the energy levels of a mechanical oscillator. We find that the heating of the membrane, caused by the interaction with the environment and unwanted couplings, can be suppressed for carefully designed electromechanical systems. The results suggest that phonon number measurement is within reach for modern electromechanical setups.Comment: 8 pages, 5 figures plus 24 pages, 11 figures supplemental materia

    Genome Sizes and the Benford Distribution

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    BACKGROUND: Data on the number of Open Reading Frames (ORFs) coded by genomes from the 3 domains of Life show the presence of some notable general features. These include essential differences between the Prokaryotes and Eukaryotes, with the number of ORFs growing linearly with total genome size for the former, but only logarithmically for the latter. RESULTS: Simply by assuming that the (protein) coding and non-coding fractions of the genome must have different dynamics and that the non-coding fraction must be particularly versatile and therefore be controlled by a variety of (unspecified) probability distribution functions (pdf's), we are able to predict that the number of ORFs for Eukaryotes follows a Benford distribution and must therefore have a specific logarithmic form. Using the data for the 1000+ genomes available to us in early 2010, we find that the Benford distribution provides excellent fits to the data over several orders of magnitude. CONCLUSIONS: In its linear regime the Benford distribution produces excellent fits to the Prokaryote data, while the full non-linear form of the distribution similarly provides an excellent fit to the Eukaryote data. Furthermore, in their region of overlap the salient features are statistically congruent. This allows us to interpret the difference between Prokaryotes and Eukaryotes as the manifestation of the increased demand in the biological functions required for the larger Eukaryotes, to estimate some minimal genome sizes, and to predict a maximal Prokaryote genome size on the order of 8-12 megabasepairs. These results naturally allow a mathematical interpretation in terms of maximal entropy and, therefore, most efficient information transmission

    Does Medical Students' Preference of Test Format (Computer-based vs. Paper-based) have an Influence on Performance?

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    <p>Abstract</p> <p>Background</p> <p>Computer-based examinations (CBE) ensure higher efficiency with respect to producibility and assessment compared to paper-based examinations (PBE). However, students often have objections against CBE and are afraid of getting poorer results in a CBE.</p> <p>The aims of this study were (1) to assess the readiness and the objections of students to a CBE vs. PBE (2) to examine the acceptance and satisfaction with the CBE on a voluntary basis, and (3) to compare the results of the examinations, which were conducted in different formats.</p> <p>Methods</p> <p>Fifth year medical students were introduced to an examination-player and were free to choose their format for the test. The reason behind the choice of the format as well as the satisfaction with the choice was evaluated after the test with a questionnaire. Additionally, the expected and achieved examination results were measured.</p> <p>Results</p> <p>Out of 98 students, 36 voluntarily chose a CBE (37%), 62 students chose a PBE (63%). Both groups did not differ concerning sex, computer-experience, their achieved examination results of the test, and their satisfaction with the chosen format. Reasons for the students' objections against CBE include the possibility for outlines or written notices, a better overview, additional noise from the keyboard or missing habits normally present in a paper based exam. The students with the CBE tended to judge their examination to be more clear and understandable. Moreover, they saw their results to be independent of the format.</p> <p>Conclusions</p> <p>Voluntary computer-based examinations lead to equal test scores compared to a paper-based format.</p

    Species' geographic distributions through time: Playing catchup with changing climates

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    This is the author's accepted manuscript.Species’ ranges are often treated as a rather fixed characteristic, rather than a fluid, ever-changing manifestation of their ecological requirements and dispersal abilities. Paleontologists generally have had a more flexible point of view on this issue than neontologists, but each perspective can improve by appreciating the other. Here, we provide an overview of paleontological and neontological perspectives on species’ geographic distributions, focusing on what can be learned about historical variations in distributions. The cross-disciplinary view, we hope, offers some novel perspectives on species-level biogeography
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