464 research outputs found

    High-field vortices in Josephson junctions with alternating critical current density

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    We study long Josephson junctions with the critical current density alternating along the junction. New equilibrium states, which we call the field synchronized or FS states, are shown to exist if the applied field is from narrow intervals centered around equidistant series of resonant fields, HmH_m. The values of HmH_m are much higher than the flux penetration field, HsH_s. The flux per period of the alternating critical current density, ϕi\phi_i, is fixed for each of the FS states. In the mm-th FS state the value of ϕi\phi_i is equal to an integer amount of flux quanta, ϕi=mϕ0\phi_i =m\phi_0. Two types of single Josephson vortices carrying fluxes ϕ0\phi_0 or/and ϕ0/2\phi_0/2 can exist in the FS states. Specific stepwise resonances in the current-voltage characteristics are caused by periodic motion of these vortices between the edges of the junction.Comment: 4 pages, 5 figure

    Maximum supercurrent in Josephson junctions with alternating critical current density

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    We consider theoretically and numerically magnetic field dependencies of the maximum supercurrent across Josephson tunnel junctions with spatially alternating critical current density. We find that two flux-penetration fields and one-splinter-vortex equilibrium state exist in long junctions.Comment: 11 pages, 8 figure

    Neuroactive steroids in depression and anxiety disorders: Clinical studies

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    Certain neuroactive steroids modulate ligand-gated ion channels via non-genomic mechanisms. Especially 3 alpha-reduced pregnane steroids are potent positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. During major depression, there is a disequilibrium of 3 alpha-reduced neuroactive steroids, which is corrected by clinically effective pharmacological treatment. To investigate whether these alterations are a general principle of successful antidepressant treatment, we studied the impact of nonpharmacological treatment options on neuroactive steroid concentrations during major depression. Neither partial sleep deprivation, transcranial magnetic stimulation, nor electroconvulsive therapy affected neuroactive steroid levels irrespectively of the response to these treatments. These studies suggest that the changes in neuroactive steroid concentrations observed after antidepressant pharmacotherapy more likely reflect distinct pharmacological properties of antidepressants rather than the clinical response. In patients with panic disorder, changes in neuroactive steroid composition have been observed opposite to those seen in depression. However, during experimentally induced panic induction either with cholecystokinine-tetrapeptide or sodium lactate, there was a pronounced decline in the concentrations of 3 alpha-reduced neuroactive steroids in patients with panic disorder, which might result in a decreased GABAergic tone. In contrast, no changes in neuroactive steroid concentrations could be observed in healthy controls with the exception of 3 alpha,5 alpha-tetrahydrodeoxycorticosterone. The modulation of GABA(A) receptors by neuroactive steroids might contribute to the pathophysiology of depression and anxiety disorders and might offer new targets for the development of novel anxiolytic compounds. Copyright (c) 2006 S. Karger AG, Basel

    Combination antiretroviral therapy and the risk of myocardial infarction

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    A Markov chain model for changes in users’ assessment of search results

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    Previous research shows that users tend to change their assessment of search results over time. This is a first study that investigates the factors and reasons for these changes, and describes a stochastic model of user behaviour that may explain these changes. In particular, we hypothesise that most of the changes are local, i.e. between results with similar or close relevance to the query, and thus belong to the same ”coarse” relevance category. According to the theory of coarse beliefs and categorical thinking, humans tend to divide the range of values under consideration into coarse categories, and are thus able to distinguish only between cross-category values but not within them. To test this hypothesis we conducted five experiments with about 120 subjects divided into 3 groups. Each student in every group was asked to rank and assign relevance scores to the same set of search results over two or three rounds, with a period of three to nine weeks between each round. The subjects of the last three-round experiment were then exposed to the differences in their judgements and were asked to explain them. We make use of a Markov chain model to measure change in users’ judgments between the different rounds. The Markov chain demonstrates that the changes converge, and that a majority of the changes are local to a neighbouring relevance category. We found that most of the subjects were satisfied with their changes, and did not perceive them as mistakes but rather as a legitimate phenomenon, since they believe that time has influenced their relevance assessment. Both our quantitative analysis and user comments support the hypothesis of the existence of coarse relevance categories resulting from categorical thinking in the context of user evaluation of search results

    Regional differences in AIDS and non-AIDS related mortality in HIV-positive individuals across Europe and Argentina: the EuroSIDA study

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    BACKGROUND Differences in access to care and treatment have been reported in Eastern Europe, a region with one of the fastest growing HIV epidemics, compared to the rest of Europe. This analysis aimed to establish whether there are regional differences in the mortality rate of HIV-positive individuals across Europe, and Argentina. METHODS 13,310 individuals under follow-up were included in the analysis. Poisson regression investigated factors associated with the risk of death. FINDINGS During 82,212 person years of follow-up (PYFU) 1,147 individuals died (mortality rate 14.0 per 1,000 PYFU (95% confidence interval [CI] 13.1-14.8). Significant differences between regions were seen in the rate of all-cause, AIDS and non-AIDS related mortality (global p<0.0001 for all three endpoints). Compared to South Europe, after adjusting for baseline demographics, laboratory measurements and treatment, a higher rate of AIDS related mortality was observed in East Europe (IRR 2.90, 95%CI 1.97-4.28, p<.0001), and a higher rate of non-AIDS related mortality in North Europe (IRR 1.51, 95%CI 1.24-1.82, p<.0001). The differences observed in North Europe decreased over calendar-time, in 2009-2011, the higher rate of non-AIDS related mortality was no longer significantly different to South Europe (IRR 1.07, 95%CI 0.66-1.75, p = 0.77). However, in 2009-2011, there remained a higher rate of AIDS-related mortality (IRR 2.41, 95%CI 1.11-5.25, p = 0.02) in East Europe compared to South Europe in adjusted analysis. INTERPRETATIONS There are significant differences in the rate of all-cause mortality among HIV-positive individuals across different regions of Europe and Argentina. Individuals in Eastern Europe had an increased risk of mortality from AIDS related causes and individuals in North Europe had the highest rate of non-AIDS related mortality. These findings are important for understanding and reviewing HIV treatment strategies and policies across the European region

    Selective complexation of divalent cations by a cyclic α,β-peptoid hexamer: a spectroscopic and computational study

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    We describe the qualitative and quantitative analysis of the complexation properties towards cations of a cyclic peptoid hexamer composed of alternating α- and β-peptoid monomers, which bear exclusively chiral (S)-phenylethyl side chains (spe) that have no noticeable chelating properties. The binding of a series of monovalent and divalent cations was assessed by 1H NMR, circular dichroism, fluorescence and molecular modelling. In contrast to previous studies on cations binding by 18-membered α-cyclopeptoid hexamers, the 21-membered cyclopeptoid cP1 did not complex monovalent cations (Na+, K+, Ag+) but showed selectivity for divalent cations (Ca2+, Ba2+, Sr2+ and Mg2+). Hexacoordinated C-3 symmetrical complexes were demonstrated for divalent cations with ionic radii around 1 Å (Ca2+ and Ba2+), while 5-coordination is preferred for divalent cations with larger (Ba2+) or smaller ionic radii (Mg2+)

    The Effectiveness of Pharmacological and Non-Pharmacological Interventions for Improving Glycaemic Control in Adults with Severe Mental Illness: A Systematic Review and Meta-Analysis

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    People with severe mental illness (SMI) have reduced life expectancy compared with the general population, which can be explained partly by their increased risk of diabetes. We conducted a meta-analysis to determine the clinical effectiveness of pharmacological and non-pharmacological interventions for improving glycaemic control in people with SMI (PROSPERO registration: CRD42015015558). A systematic literature search was performed on 30/10/2015 to identify randomised controlled trials (RCTs) in adults with SMI, with or without a diagnosis of diabetes that measured fasting blood glucose or glycated haemoglobin (HbA1c). Screening and data extraction were carried out independently by two reviewers. We used random effects meta-analysis to estimate effectiveness, and subgroup analysis and univariate meta-regression to explore heterogeneity. The Cochrane Collaboration’s tool was used to assess risk of bias. We found 54 eligible RCTs in 4,392 adults (40 pharmacological, 13 behavioural, one mixed intervention). Data for meta-analysis were available from 48 RCTs (n = 4052). Both pharmacological (mean difference (MD), -0.11mmol/L; 95% confidence interval (CI), [-0.19, -0.02], p = 0.02, n = 2536) and behavioural interventions (MD, -0.28mmol//L; 95% CI, [-0.43, -0.12], p<0.001, n = 956) were effective in lowering fasting glucose, but not HbA1c (pharmacological MD, -0.03%; 95% CI, [-0.12, 0.06], p = 0.52, n = 1515; behavioural MD, 0.18%; 95% CI, [-0.07, 0.42], p = 0.16, n = 140) compared with usual care or placebo. In subgroup analysis of pharmacological interventions, metformin and antipsychotic switching strategies improved HbA1c. Behavioural interventions of longer duration and those including repeated physical activity had greater effects on fasting glucose than those without these characteristics. Baseline levels of fasting glucose explained some of the heterogeneity in behavioural interventions but not in pharmacological interventions. Although the strength of the evidence is limited by inadequate trial design and reporting and significant heterogeneity, there is some evidence that behavioural interventions, antipsychotic switching, and metformin can lead to clinically important improvements in glycaemic measurements in adults with SMI

    Menstrual Dysfunction and Treatment Among Adolescents With Congenital Heart Disease

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    Study Objective This study describes menstrual dysfunction and treatment among adolescent and young adult (AYA) females with congenital heart disease (CHD). Design Data collected from a 1-time survey completed by AYA females (and mothers if AYA unable). Setting Participants were recruited from pediatric cardiology clinics. Participants Female AYA with CHD, aged 14-21 years (N = 114). Interventions None. Main Outcome Measures The questionnaire assessed sexual and reproductive health (SRH) concerns, behaviors, and management. Outcome measures were self-reported menstrual complaints, use of over-the-counter (OTC) pain relief medications for dysmenorrhea, reported visits with a clinician for a menstrual problem, and reported use of hormones for menstrual problems or birth control. Results Mean age was 17.0 years (SD = 2.2). The majority of participants (83%) reported 1 or more menstrual complaints (67.5% cramping, 42.1% irregular menses, 46.5% heavy periods), and 88% reported any history of taking OTC medications for pain relief. Increased menstrual complaints were not associated with level of cardiac complexity, reported transplantation, or reported use of hormonal contraception. However, 32% of participants reported use of hormonal contraception for menstrual dysfunction. Combined oral contraceptive pills (COCs) were the most common; 2 of these women carried contraindications to estrogen. Conclusions A large majority of AYA females with CHD reported menstrual dysfunction. Use of OTC medication for menstrual pain and inappropriate use of estrogen creates concerns that menstrual disorders may be unaddressed or addressed inappropriately. Thus, gynecological needs of adolescents with CHD may need to be specifically targeted by providers who feel comfortable with this population and their complex needs
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