975 research outputs found

    The two-dimensional two-component plasma plus background on a sphere : Exact results

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    An exact solution is given for a two-dimensional model of a Coulomb gas, more general than the previously solved ones. The system is made of a uniformly charged background, positive particles, and negative particles, on the surface of a sphere. At the special value Γ=2\Gamma = 2 of the reduced inverse temperature, the classical equilibrium statistical mechanics is worked out~: the correlations and the grand potential are calculated. The thermodynamic limit is taken, and as it is approached the grand potential exhibits a finite-size correction of the expected universal form.Comment: 23 pages, Plain Te

    Plasma macrophage colony-stimulating factor levels during cardiopulmonary bypass with extracorporeal circulation

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    Leukocytosis and thrombocytopenia occur during cardiopulmonary bypass (CPB) with extracorporeal circulation (ECC). Elevated circulating concentrations of macrophage colony-stimulating factor (M-CSF) are reported during thrombocytopenia and leukopenia of different origins. We have assessed M-CSF concentrations in 40 patients undergoing CPB with ECC. Plasma M-CSF concentrations were stable during ECC and increased at the 6th (7.3 ± 0.7 IU/μg protein) and 24th (8.6 ± 0.8 IU/μg protein) postoperative hour compared with pre-ECC values (4.9 ± 0.5 IU/μg protein). A deep thrombocytopenia was found during ECC and until the 24th postoperative hour. A drop of leukocyte counts was found during ECC followed by an increase after ECC weaning. While no correlation was found between M-CSF concentrations and the leukocyte counts, M-CSF values were positively correlated with platelet counts only before and during ECC. Thus, M-CSF is not implicated in the thrombocytopenia and the leukopenia generated during CPB with ECC. However the elevated levels of M-CSFa few hours after the end of ECC might play a role in the inflammatory process often observed after CPB

    Tumour necrosis factor-alpha (TNFα) stimulates the growth of human bone marrow stromal cells

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    This study reports that TNF-α is a potent mitogen for human bone marrow sternal cells in vitro (assessed by [3H]-thymidine incorporation into DNA and cell counts). In contrast, cytokines such as IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-6, LIF, SCF, M-CSF, G-CSF and GM-CSF had no effect. The effect of TNF-α on the growth of human bone marrow stromal cells could be of importance during inflammatory processes which take place in the marrow, for example marrow fibrosis

    Casimir force between two ideal-conductor walls revisited

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    The high-temperature aspects of the Casimir force between two neutral conducting walls are studied. The mathematical model of "inert" ideal-conductor walls, considered in the original formulations of the Casimir effect, is based on the universal properties of the electromagnetic radiation in the vacuum between the conductors, with zero boundary conditions for the tangential components of the electric field on the walls. This formulation seems to be in agreement with experiments on metallic conductors at room temperature. At high temperatures or large distances, at least, fluctuations of the electric field are present in the bulk and at the surface of a particle system forming the walls, even in the high-density limit: "living" ideal conductors. This makes the enforcement of the inert boundary conditions inadequate. Within a hierarchy of length scales, the high-temperature Casimir force is shown to be entirely determined by the thermal fluctuations in the conducting walls, modelled microscopically by classical Coulomb fluids in the Debye-H\"{u}ckel regime. The semi-classical regime, in the framework of quantum electrodynamics, is studied in the companion letter by P.R.Buenzli and Ph.A.Martin, cond-mat/0506363, Europhys.Lett.72, 42 (2005).Comment: 7 pages.One reference updated. Domain of validity of eq.(11) correcte

    Digit ratio and autism spectrum disorders in the Avon Longitudinal Study of Parents and Children:a birth cohort study

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    OBJECTIVES: To investigate whether second-to-fourth digit ratio (2D:4D), a measure commonly used as a proxy for fetal testosterone exposure, is associated with autism spectrum disorders (ASDs), as predicted by the extreme male brain theory of autism. DESIGN: A birth cohort study. SETTING: The Avon Longitudinal Study of Parents and Children (ALSPAC). PARTICIPANTS: 6015 ALSPAC children with data on digit ratio, at least 1 outcome measure and information on potential confounding variables (parental occupational class, maternal education and age at digit ratio measurement). Digit ratio was measured by the photocopy and calliper method. OUTCOMES: ASD diagnosis (cases were identified previously by record linkage or maternal report) and 4 measures that combine optimally within ALSPAC to predict ASD: the Children's Communication Checklist (coherence subscale), the Social and Communication Disorders Checklist, a repetitive behaviour measure, and the Emotionality, Activity and Sociability scale (sociability subscale). These measures were dichotomised, with approximately 10% defined as the ‘risk’ group. RESULTS: Using logistic regression, we examined the association of 2D:4D with ASDs and 4 dichotomised ASD traits. Covariates were occupational class, maternal education and age at 2D:4D measurement. 2D:4D was not associated with ASDs in males (adjusted OR per 1 SD increase in mean 2D:4D, 0.88 (95% CI 0.65 to 1.21), p=0.435) or females (adjusted OR=1.36 (95% CI 0.81 to 2.28), p=0.245). Similar results were observed after adjustment for IQ. There was 1 weak association between reduced coherence and increased left 2D:4D in males, in the opposite direction to that predicted by the extreme male brain theory (adjusted OR=1.15 (95% CI 1.02 to 1.29), p=0.023). Given multiple comparisons, this is consistent with chance. CONCLUSIONS: In this population-based study, there was no strong evidence of an association between 2D:4D and ASD diagnosis or traits, although the CIs were wide. These results are not consistent with the extreme male brain theory

    Fostering collective intelligence education

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    New educational models are necessary to update learning environments to the digitally shared communication and information. Collective intelligence is an emerging field that already has a significant impact in many areas and will have great implications in education, not only from the side of new methodologies but also as a challenge for education. This paper proposes an approach to a collective intelligence model of teaching using Internet to combine two strategies: idea management and real time assessment in the class. A digital tool named Fabricius has been created supporting these two elements to foster the collaboration and engagement of students in the learning process. As a result of the research we propose a list of KPI trying to measure individual and collective performance. We are conscious that this is just a first approach to define which aspects of a class following a course can be qualified and quantified.Postprint (published version

    Self-consistent equation for an interacting Bose gas

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    We consider interacting Bose gas in thermal equilibrium assuming a positive and bounded pair potential V(r)V(r) such that 0<\int d\br V(r) = a<\infty. Expressing the partition function by the Feynman-Kac functional integral yields a classical-like polymer representation of the quantum gas. With Mayer graph summation techniques, we demonstrate the existence of a self-consistent relation ρ(μ)=F(μaρ(μ))\rho (\mu)=F(\mu-a\rho(\mu)) between the density ρ\rho and the chemical potential μ\mu, valid in the range of convergence of Mayer series. The function FF is equal to the sum of all rooted multiply connected graphs. Using Kac's scaling V_{\gamma}(\br)=\gamma^{3}V(\gamma r) we prove that in the mean-field limit γ0\gamma\to 0 only tree diagrams contribute and function FF reduces to the free gas density. We also investigate how to extend the validity of the self-consistent relation beyond the convergence radius of Mayer series (vicinity of Bose-Einstein condensation) and study dominant corrections to mean field. At lowest order, the form of function FF is shown to depend on single polymer partition function for which we derive lower and upper bounds and on the resummation of ring diagrams which can be analytically performed.Comment: 33 pages, 6 figures, submitted to Phys.Rev.

    Management of drug-disease interactions:a best practice from the Netherlands

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    Background Drug-disease interactions are situations where pharmacotherapy may have a negative effect on patients' comorbidities. In these cases, it can be necessary to avoid that drug, adjust its dose or monitor therapy. In the Netherlands, pharmacists have developed a best practice how to systematically evaluate drug-disease interactions based on pharmacological considerations and implement recommendations for specific drug-disease interactions. Aim To describe the development of recommendations for drug-disease interactions and the implementation in prescribing and dispensing practice in the Netherlands. Setting Pharmacies and physicians' practices in primary care and hospitals in the Netherlands. Development A multi-disciplinary expert panel assessed if diseases had clinically relevant drug-disease interactions and evaluated drug-disease interactions by literature review and expert opinion, and subsequently developed practice recommendations. Implementation The recommendations were implemented in all clinical decision support systems in primary care and hospitals throughout the Netherlands. Evaluation Recommendations were developed for 57 diseases and conditions. Cardiovascular diseases have the most drug-disease interactions (n = 12, e.g. long QT-syndrome, heart failure), followed by conditions related to the reproductive system (n = 7, e.g. pregnancy). The number of drugs with recommendations differed between 6 for endometriosis and tympanostomy tubes, and up to 1171 in the case of porphyria or even all drugs for pregnancy. Conclusion Practice recommendations for drug-disease interactions were developed, and implemented in prescribing and dispensing practice. These recommendations support both pharmacists and physicians by signalling clinically relevant drug-disease interactions at point of care, thereby improving medication safety. This practice may be adopted and contribute to safer medication use in other countries as well

    Charge and Density Fluctuations Lock Horns : Ionic Criticality with Power-Law Forces

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    How do charge and density fluctuations compete in ionic fluids near gas-liquid criticality when quantum mechanical effects play a role ? To gain some insight, long-range Φ±±L/rd+σ\Phi^{{\mathcal{L}}}_{\pm \pm} / r^{d+\sigma} interactions (with σ>0\sigma>0), that encompass van der Waals forces (when σ=d=3\sigma = d = 3), have been incorporated in exactly soluble, dd-dimensional 1:1 ionic spherical models with charges ±q0\pm q_0 and hard-core repulsions. In accord with previous work, when d>min{σ,2}d>\min \{\sigma, 2\} (and q0q_0 is not too large), the Coulomb interactions do not alter the (q0=0q_0 = 0) critical universality class that is characterized by density correlations at criticality decaying as 1/rd2+η1/r^{d-2+\eta} with η=max{0,2σ}\eta = \max \{0, 2-\sigma\}. But screening is now algebraic, the charge-charge correlations decaying, in general, only as 1/rd+σ+41/r^{d+\sigma+4}; thus σ=3\sigma = 3 faithfully mimics known \textit{non}critical d=3d=3 quantal effects. But in the \textit{absence} of full (+,+, -) ion symmetry, density and charge fluctuations mix via a transparent mechanism: then the screening \textit{at criticality} is \textit{weaker} by a factor r42ηr^{4-2\eta}. Furthermore, the otherwise valid Stillinger-Lovett sum rule fails \textit{at} criticality whenever η=0\eta =0 (as, e.g., when σ>2\sigma>2) although it remains valid if η>0\eta >0 (as for σ<2\sigma<2 or in real d3d \leq 3 Ising-type systems).Comment: 8 pages, in press in J. Phys. A, Letters to the Edito
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