236 research outputs found

    Anisotropic pure-phase plates for quality improvement of partially coherent, partially polarized beams

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    From a theoretical point of view, the use of anisotropic pure-phase plates (APP) is considered in order to improve the quality parameter of certain partially coherent, partially polarized beams. It is shown that, to optimize the beam-quality parameter, the phases of the two Cartesian components of the field at the output of the APP plate should, be identical and should exhibit a quadratic dependence on the radial polar coordinate

    Higgs-mediated FCNCs: Natural Flavour Conservation vs. Minimal Flavour Violation

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    We compare the effectiveness of two hypotheses, Natural Flavour Conservation (NFC) and Minimal Flavour Violation (MFV), in suppressing the strength of flavour-changing neutral-currents (FCNCs) in models with more than one Higgs doublet. We show that the MFV hypothesis, in its general formulation, is more stable in suppressing FCNCs than the hypothesis of NFC alone when quantum corrections are taken into account. The phenomenological implications of the two scenarios are discussed analysing meson-antimeson mixing observables and the rare decays B -> mu+ mu-. We demonstrate that, introducing flavour-blind CP phases, two-Higgs doublet models respecting the MFV hypothesis can accommodate a large CP-violating phase in Bs mixing, as hinted by CDF and D0 data and, without extra free parameters, soften significantly in a correlated manner the observed anomaly in the relation between epsilon_K and S_psi_K.Comment: 27 pages, 4 figures. v3: minor modifications (typos corrected and few refs. added), conclusions unchanged; journal versio

    Physics of Neutron Star Crusts

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    The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

    Modulation of the immune response by nematode secreted acetylcholinesterase revealed by heterologous expression in Trypanosoma musculi

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    Nematode parasites secrete molecules which regulate the mammalian immune system, but their genetic intractability is a major impediment to identifying and characterising the biological effects of these molecules. We describe here a novel system for heterologous expression of helminth secreted proteins in the natural parasite of mice, Trypanosoma musculi, which can be used to analyse putative immunomodulatory functions. Trypanosomes were engineered to express a secreted acetylcholinesterase from Nippostrongylus brasiliensis. Infection of mice with transgenic parasites expressing acetylcholinesterase resulted in truncated infection, with trypanosomes cleared early from the circulation. Analysis of cellular phenotypes indicated that exposure to acetylcholinesterase in vivo promoted classical activation of macrophages (M1), with elevated production of nitric oxide and lowered arginase activity. This most likely occurred due to the altered cytokine environment, as splenocytes from mice infected with T. musculi expressing acetylcholinesterase showed enhanced production of IFNγ and TNFα, with diminished IL-4, IL-13 and IL-5. These results suggest that one of the functions of nematode secreted acetylcholinesterase may be to alter the cytokine environment in order to inhibit development of M2 macrophages which are deleterious to parasite survival. Transgenic T. musculi represents a valuable new vehicle to screen for novel immunoregulatory proteins by extracellular delivery in vivo to the murine host

    Compressed representation of a partially defined integer function over multiple arguments

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    In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

    Epidemiology, clinical features, and antimicrobial resistance of invasive Escherichia coli disease in patients admitted in tertiary care hospitals

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    Background Invasive Escherichia coli disease (IED), including bloodstream infection, sepsis, and septic shock, can lead to high hospitalization and mortality rates. This multinational study describes the clinical profile of IED in tertiary care hospital patients. Methods We applied clinical criteria of systemic inflammatory response syndrome (SIRS), sepsis, or septic shock to hospitalized patients with culture-confirmed E. coli from urine or a presumed sterile site. We assessed a proposed clinical case definition against physician diagnoses. Results Most IED patients (N=902) were adults aged ≥60 years (76.5%); 51.9%, 25.1%, and 23.0% of cases were community-acquired (CA), hospital-acquired (HA), and healthcare-associated (HCA), respectively. The urinary tract was the most common source of infection (52.3%). SIRS, sepsis, and septic shock were identified in 77.4%, 65.3% and 14.1% of patients, respectively. Patients >60 years were more likely to exhibit organ dysfunction than those ≤60 years; this trend was not observed for SIRS. The case fatality rate (CFR) was 20.0% (60–75 years, 21.5%; ≥75 years, 22.2%), with an increase across IED acquisition settings (HA, 28.3%; HCA, 21.7% vs. CA, 15.2%). Noticeably, 77.8% of patients initiated antibiotic use on the day of culture sample collection. 65.6% and 40.8% of E. coli isolates were resistant to ≥1 agent in ≥1 or ≥2 drug class(es). A 96.1% agreement was seen between the proposed clinical case definition and physician’s diagnoses of IED. Conclusion This study contributes valuable real-world data about IED severity. An accepted case definition could promote timely and accurate diagnosis of IED and inform the development of novel preventative strategies
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