874 research outputs found

    A numerical study of two-photon ionization of helium using the Pyprop framework

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    Few-photon induced breakup of helium is studied using a newly developed ab initio numerical framework for solving the six-dimensional time-dependent Schroedinger equation. We present details of the method and calculate (generalized) cross sections for the process of two-photon nonsequential (direct) double ionization at photon energies ranging from 39.4 to 54.4 eV, a process that has been very much debated in recent years and is not yet fully understood. In particular, we have studied the convergence property of the total cross section in the vicinity of the upper threshold (54.4 eV), versus the pulse duration of the applied laser field. We find that the cross section exhibits an increasing trend near the threshold, as has also been observed by others, and show that this rise cannot solely be attributed to an unintended inclusion of the sequential two-photon double ionization process, caused by the bandwidth of the applied field.Comment: 7 pages, 3 figure

    Glomerulonephritis and malignancy: A population-based analysis

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    Glomerulonephritis and malignancy: A population-based analysis.BackgroundAn association between glomerulonephritis and malignant tumors has previously both been found and discarded in clinical series, but to our knowledge never has been tested in a population-based setting.MethodsThe Danish Kidney Biopsy Registry includes all kidney biopsies performed from 1985. Using a unique personal identification number, each person in the registry to the National Population Registry and the Danish Cancer Registry were linked. Cancer occurrence after the biopsy was compared in patients with morphological, glomerular diseases with that of the general Danish population, taking into account sex, age, calendar period and time since biopsy, and the 95% confidence interval (95% CI) for the observed-to-expected rates was calculated, assuming a Poisson distribution. Cancer occurrence was stratified to <1 year, 1 to 4, and ≄5 years after a biopsy.ResultsA total of 102 de novo cancers were found in 1958 patients. These cancers represent a two- to threefold excess of the expected number at <1 and 1 to 4, but not ≄5 years after a biopsy. Non-Hodgkin's lymphomas were observed six to eight times more than expected. Cancer excess was seen in glomerulonephritides with a known or suspected virus etiology.ConclusionsThe excess cancer rate could be the result of underlying undiagnosed tumors whose antigens have initiated glomerulonephritis, or the immunosuppressive therapy that initiated or energized tumor cells. Based on the findings in our study, there is some support for an association to persistent viruses causing first the glomerulonephritides and then the malignancies, perhaps through a common pathogenesis. This calls for other studies to be done that are specifically designed to investigate this issue, with more data on patient characteristics and confounders

    Factors Affecting the Degradation Processes for Dextran

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    Author Institution: Departments of Bacteriology and Chemistry, The Ohio State University, Columbus 1

    Long-term glycaemic control with metformin– sulphonylurea–pioglitazone triple therapy in PROactive (PROactive 17)

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    peer reviewedAims We assessed the long-term glycaemic effects and the safety profile of triple therapy with the addition of pioglitazone vs. placebo in patients with Type 2 diabetes treated with combined metformin–sulphonylurea therapy in the PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive). Methods In a post-hoc analysis, we identified patients treated with metformin plus sulphonylurea combination therapy and not receiving insulin at baseline (n = 1314). In those patients, we compared the effects of pioglitazone (force-titrated to 45 mg⁄ day, n = 654) vs. placebo (n = 660) on glycated haemoglobin (HbA1c) reduction, concomitant changes in medications and initiation of permanent insulin use (defined as daily insulin use for a period of ‡ 90 days or ongoing use at death ⁄ final visit). Results Significantly greater reductions in HbA1c and greater proportions of patients with HbA1c at target were noted with pioglitazone vs, placebo, despite a decrease in the use of other oral glucose-lowering agents. Therewas an approximate twofold increase in progression to permanent insulin use in the placebo group vs. the pioglitazone group: 31.1 vs. 16.1%, respectively, when added to combination therapy. The overall safety of themetformin–sulphonylurea–pioglitazone triple therapy was good. Conclusions Intensifying an existing dual oral therapy regimen to a triple oral regimen by adding pioglitazone to the classical metformin–sulphonylurea combination resulted in sustained improvements in glycaemic control and reduced progression to insulin therapy. The advantages and disadvantages of adding pioglitazone instead of adding basal insulin should be assessed further

    High-Frequency Temperature Variability Mirrors Fixed Differences in Thermal Limits of the Massive Coral \u3ci\u3ePorites lobata\u3c/i\u3e

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    Spatial heterogeneity in environmental characteristics can drive adaptive differentiation when contrasting environments exert divergent selection pressures. This environmental and genetic heterogeneity can substantially influence population and community resilience to disturbance events. Here, we investigated corals from the highly variable back-reef habitats of Ofu Island in American Samoa that thrive in thermal conditions known to elicit widespread bleaching and mortality elsewhere. To investigate the relative importance of acclimation versus site of origin in shaping previously observed differences in coral tolerance limits at Ofu Island, specimens of the common Indo-Pacific coral Porites lobata from locations with differing levels of thermal variability were acclimated to low and high thermal variation in controlled common garden aquaria. Overall, there were minimal effects of the acclimation exposure. Corals native to the site with the highest level of daily variability grew fastest, regardless of acclimation treatment. When exposed to lethal thermal stress, corals native to both variable sites contained elevated levels of heat shock proteins and maintained photosynthetic performance for 1–2 days longer than corals from the stable environment. Despite being separated by \u3c5 \u3ekm, there was significant genetic differentiation among coral colonies (FST=0.206, PCladocopium sp. (ITS type C15). Our study demonstrates consistent signatures of adaptation in growth and stress resistance in corals from naturally thermally variable habitats, suggesting that differences in the amount of thermal variability may be an important contributor to adaptive differentiation in reef-building corals

    Quantum effects on Lagrangian points and displaced periodic orbits in the Earth-Moon system

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    Recent work in the literature has shown that the one-loop long distance quantum corrections to the Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial mechanics, i.e., at the Lagrangian libration points of stable equilibrium the planetoid is not exactly at equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed by a few millimeters in the Earth-Moon system. First, we assess such a theoretical calculation by exploiting the full theory of the quintic equation, i.e., its reduction to Bring-Jerrard form and the resulting expression of roots in terms of generalized hypergeometric functions. By performing the numerical analysis of the exact formulas for the roots, we confirm and slightly improve the theoretical evaluation of quantum corrected coordinates of Lagrangian libration points of stable equilibrium. Second, we prove in detail that also for collinear Lagrangian points the quantum corrections are of the same order of magnitude in the Earth-Moon system. Third, we discuss the prospects to measure, with the help of laser ranging, the above departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced periodic orbits of solar sails at all libration points, both stable and unstable. The present paper investigates therefore, eventually, a restricted three-body problem involving Earth, Moon and a solar sail. By taking into account the one-loop quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist

    Observation of confined current ribbon in JET plasmas

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    we report the identification of a localised current structure inside the JET plasma. It is a field aligned closed helical ribbon, carrying current in the same direction as the background current profile (co-current), rotating toroidally with the ion velocity (co-rotating). It appears to be located at a flat spot in the plasma pressure profile, at the top of the pedestal. The structure appears spontaneously in low density, high rotation plasmas, and can last up to 1.4 s, a time comparable to a local resistive time. It considerably delays the appearance of the first ELM.Comment: 10 pages, 6 figure

    The efficacy of psychological interventions for PTSD in children and adolescents exposed to single vs. multiple traumas. Meta-analysis of randomized controlled trials

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    Background: Previous meta-analyses of psychotherapies for children and adolescents with post-traumatic stress disorder (PTSD) did not investigate whether treatment efficacy is diminished when patients report multiple (versus single) traumas. Aims: To examine whether efficacy of psychological interventions for paediatric PTSD is diminished when patients report multiple (versus single) traumas. Method: We systematically searched PsycInfo, MEDLINE, Web of Science and PTSDpubs on 21 April 2022 and included randomised controlled trials (RCTs) meeting the following criteria: (a) random allocation; (b) all participants presented with partial or full PTSD; (c) PTSD is the primary treatment focus; (d) sample mean age <19 years; (e) sample size n ≄ 20. Trauma frequency was analysed as a dichotomous (single versus ≄2 traumas) and continuous (mean number of exposures) potential moderator of efficacy. Results: Of the 57 eligible RCTs (n = 4295), 51 RCTs were included in quantitative analyses. Relative to passive control conditions, interventions were found effective for single-trauma-related PTSD (Hedges’ g = 1.09; 95% CI 0.70–1.48; k = 8 trials) and multiple-trauma-related PTSD (g = 1.11; 95% CI 0.74–1.47; k = 12). Psychotherapies were also more effective than active control conditions in reducing multiple-trauma-related PTSD. Comparison with active control conditions regarding single-event PTSD was not possible owing to scarcity (k = 1) of available trials. Efficacy did not differ with trauma exposure frequency irrespective of its operationalisation and subgroup analyses (e.g. trauma-focused cognitive–behavioural therapy only). Conclusions: The current evidence base suggests that psychological interventions for paediatric PTSD can effectively treat PTSD in populations reporting single and multiple traumas. Future trials for PTSD following single-event trauma need to involve active control conditions

    Ricci-flat Metrics with U(1) Action and the Dirichlet Boundary-value Problem in Riemannian Quantum Gravity and Isoperimetric Inequalities

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    The Dirichlet boundary-value problem and isoperimetric inequalities for positive definite regular solutions of the vacuum Einstein equations are studied in arbitrary dimensions for the class of metrics with boundaries admitting a U(1) action. We show that in the case of non-trivial bundles Taub-Bolt infillings are double-valued whereas Taub-Nut and Eguchi-Hanson infillings are unique. In the case of trivial bundles, there are two Schwarzschild infillings in arbitrary dimensions. The condition of whether a particular type of filling in is possible can be expressed as a limitation on squashing through a functional dependence on dimension in each case. The case of the Eguchi-Hanson metric is solved in arbitrary dimension. The Taub-Nut and the Taub-Bolt are solved in four dimensions and methods for arbitrary dimension are delineated. For the case of Schwarzschild, analytic formulae for the two infilling black hole masses in arbitrary dimension have been obtained. This should facilitate the study of black hole dynamics/thermodynamics in higher dimensions. We found that all infilling solutions are convex. Thus convexity of the boundary does not guarantee uniqueness of the infilling. Isoperimetric inequalities involving the volume of the boundary and the volume of the infilling solutions are then investigated. In particular, the analogues of Minkowski's celebrated inequality in flat space are found and discussed providing insight into the geometric nature of these Ricci-flat spaces.Comment: 40 pages, 3 figure

    Haemoglobin mass and running time trial performance after recombinant human erythropoietin administration in trained men

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    &lt;p&gt;Recombinant human erythropoietin (rHuEpo) increases haemoglobin mass (Hbmass) and maximal oxygen uptake (v˙ O2 max).&lt;/p&gt; &lt;p&gt;Purpose: This study defined the time course of changes in Hbmass, v˙ O2 max as well as running time trial performance following 4 weeks of rHuEpo administration to determine whether the laboratory observations would translate into actual improvements in running performance in the field.&lt;/p&gt; &lt;p&gt;Methods: 19 trained men received rHuEpo injections of 50 IUNkg21 body mass every two days for 4 weeks. Hbmass was determined weekly using the optimized carbon monoxide rebreathing method until 4 weeks after administration. v˙ O2 max and 3,000 m time trial performance were measured pre, post administration and at the end of the study.&lt;/p&gt; &lt;p&gt;Results: Relative to baseline, running performance significantly improved by ,6% after administration (10:3061:07 min:sec vs. 11:0861:15 min:sec, p,0.001) and remained significantly enhanced by ,3% 4 weeks after administration (10:4661:13 min:sec, p,0.001), while v˙ O2 max was also significantly increased post administration (60.765.8 mLNmin21Nkg21 vs. 56.066.2 mLNmin21Nkg21, p,0.001) and remained significantly increased 4 weeks after rHuEpo (58.065.6 mLNmin21Nkg21, p = 0.021). Hbmass was significantly increased at the end of administration compared to baseline (15.261.5 gNkg21 vs. 12.761.2 gNkg21, p,0.001). The rate of decrease in Hbmass toward baseline values post rHuEpo was similar to that of the increase during administration (20.53 gNkg21Nwk21, 95% confidence interval (CI) (20.68, 20.38) vs. 0.54 gNkg21Nwk21, CI (0.46, 0.63)) but Hbmass was still significantly elevated 4 weeks after administration compared to baseline (13.761.1 gNkg21, p&#60;0.001).&lt;/p&gt; &lt;p&gt;Conclusion: Running performance was improved following 4 weeks of rHuEpo and remained elevated 4 weeks after administration compared to baseline. These field performance effects coincided with rHuEpo-induced elevated v˙ O2 max and Hbmass.&lt;/p&gt
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