1,169 research outputs found

    Treatment-limiting decisions, comorbidities, and mortality in the emergency departments: a cross-sectional elderly population-based study

    Get PDF
    BACKGROUND: Older adults experience a higher risk of death in the emergency departments (EDs), in part, as a result of their comorbidities. A treatment-limiting decision is often reported for older adults who die in the EDs. The Charlson Comorbidity Index (CCI) is a validated method for the scoring of comorbidities. Whether an association between the CCI and treatment-limiting decisions exists remains unknown. OBJECTIVE: To determine whether the CCI was associated with the treatment-limiting decisions made for older patients who die in the EDs. METHODS: A total of 2,095 patients >/=65 years old who died in the EDs in France and Belgium were prospectively included between 2004 and 2005. The recorded data included: 1) the CCI score; 2) patient age; 3) gender; 4) living in senior housing facilities; 5) hospitalizations occurring in the previous year; 6) presence of functional limitations (according to the Knaus classification); 7) chronic diseases; and 8) presence of organ failure(s). A treatment-limiting decision was defined as a predetermined choice not to implement therapies that would otherwise be required to sustain life. RESULTS: A treatment-limiting decision was identified in 993 (47%) patients. Fully-adjusted logistic regression model showed that a CCI >/= 5 (OR=25.56 with P=0.037), age >/=85years (OR=20.33 with P<0.001), living in an institution (OR=0.15 with P=0.017), hematologic (OR=6.92 with P=0.020) and respiratory disease (OR=0.17 with P=0.046), and neurologic causes (OR=0.20 with P=0.010) of organ failure were significantly associated with treatment-limiting decisions. CONCLUSION: An elevated CCI score (>/=5) was associated with a treatment-limiting decision in elderly patients evaluated in the EDs. Further research is needed to corroborate this finding

    Optical chirality without optical activity: How surface plasmons give a twist to light

    Full text link
    Light interacts differently with left and right handed three dimensional chiral objects, like helices, and this leads to the phenomenon known as optical activity. Here, by applying a polarization tomography, we show experimentally, for the first time in the visible domain, that chirality has a different optical manifestation for twisted planar nanostructured metallic objects acting as isolated chiral metaobjects. Our analysis demonstrate how surface plasmons, which are lossy bidimensional electromagnetic waves propagating on top of the structure, can delocalize light information in the just precise way for giving rise to this subtle effect.Comment: Opt. Express 16, 12559 (2008

    Spectral functions from Hadronic Tau Decays and QCD

    Full text link
    Hadronic decays of the Ď„\tau lepton provide a clean environment to study hadron dynamics in an energy regime dominated by resonances, with the interesting information captured in the spectral functions. Recent results from ALEPH on exclusive channels are presented, with some emphasis on the \pi \piz final state which plays a crucial role for the determination of the hadronic contribution to the muon anomalous magnetic moment. Inclusive spectral functions are the basis for QCD analyses, delivering an accurate determination of the strong coupling constant, quantitative information on nonperturbative contributions and a measurement of the mass of the strange quark.Comment: 14 pages, 18 figures, invited talk at the Tau02 Workshop, Santa Cruz, Sept. 200

    Tau Lepton Physics: Theory Overview

    Get PDF
    The pure leptonic or semileptonic character of tau decays makes them a good laboratory to test the structure of the weak currents and the universality of their couplings to the gauge bosons. The hadronic tau decay modes constitute an ideal tool for studying low-energy effects of the strong interactions in very clean conditions; a well-known example is the precise determination of the QCD coupling from tau-decay data. New physics phenomena, such as a non-zero tau-neutrino mass or violations of (flavour / CP) conservation laws can also be searched for with tau decays.Comment: 20 pages, latex, 5 Postscript figures, uses espcrc2.sty, Invited Talk at the Fourth International Workshop on Tau Lepton Physics (TAU96), Colorado, September 199

    V_us and m_s from hadronic tau decays

    Get PDF
    Recent experimental results on hadronic tau decays into strange particles by the OPAL collaboration are employed to determine V_us and m_s from moments of the invariant mass distribution. Our results are V_us = 0.2208+-0.0034 and m_s(2 GeV) = 81+-22 MeV. The error on V_us is dominated by experiment, and should be improvable in the future. Nevertheless, already now our result is competitive to the standard extraction of V_us from K_e3 decays, and it is compatible with unitarity.Comment: 4 pages, 1 figur

    Diffusive Shock Acceleration and Reconnection Acceleration Processes

    Get PDF
    Shock waves, as shown by simulations and observations, can generate high levels of downstream vortical turbulence, including magnetic islands. We consider a combination of diffusive shock acceleration (DSA) and downstream magnetic-island-reconnection-related processes as an energization mechanism for charged particles. Observations of electron and ion distributions downstream of interplanetary shocks and the heliospheric termination shock (HTS) are frequently inconsistent with the predictions of classical DSA. We utilize a recently developed transport theory for charged particles propagating diffusively in a turbulent region filled with contracting and reconnecting plasmoids and small-scale current sheets. Particle energization associated with the anti-reconnection electric field, a consequence of magnetic island merging, and magnetic island contraction, are considered. For the former only, we find that (i) the spectrum is a hard power law in particle speed, and (ii) the downstream solution is constant. For downstream plasmoid contraction only, (i) the accelerated spectrum is a hard power law in particle speed; (ii) the particle intensity for a given energy peaks downstream of the shock, and the distance to the peak location increases with increasing particle energy, and (iii) the particle intensity amplification for a particular particle energy, f(x,c/c_0)/f(0,c/c_0), is not 1, as predicted by DSA, but increases with increasing particle energy. The general solution combines both the reconnection-induced electric field and plasmoid contraction. The observed energetic particle intensity profile observed by Voyager 2 downstream of the HTS appears to support a particle acceleration mechanism that combines both DSA and magnetic-island-reconnection-related processes

    Particle acceleration and reconnection in the solar wind

    Get PDF
    An emerging paradigm for the dissipation of magnetic turbulence in the supersonic solar wind is via localized quasi-2D small-scale magnetic island reconnection processes. An advection-diffusion transport equation for a nearly isotropic particle distribution describes particle transport and energization in a region of interacting magnetic islands [1; 2]. The dominant charged particle energization processes are 1) the electric field induced by quasi-2D magnetic island merging, and 2) magnetic island contraction. The acceleration of charged particles in a “sea of magnetic islands” in a super-Alfvénic flow, and the energization of particles by combined diffusive shock acceleration (DSA) and downstream magnetic island reconnection processes are discussed

    Injection of thermal and suprathermal seed particles into coronal shocks of varying obliquity

    Get PDF
    Context. Diffusive shock acceleration in the solar corona can accelerate solar energetic particles to very high energies. Acceleration efficiency is increased by entrapment through self-generated waves, which is highly dependent on the amount of accelerated particles. This, in turn, is determined by the efficiency of particle injection into the acceleration process. Aims. We present an analysis of the injection efficiency at coronal shocks of varying obliquity.We assessed injection through reflection and downstream scattering, including the effect of a cross-shock potential. Both quasi-thermal and suprathermal seed populations were analysed. We present results on the effect of cross-field diffusion downstream of the shock on the injection efficiency. Methods. Using analytical methods, we present applicable injection speed thresholds that were compared with both semi-analytical flux integration and Monte Carlo simulations, which do not resort to binary thresholds. Shock-normal angle θBn and shock-normal velocity Vs were varied to assess the injection efficiency with respect to these parameters. Results. We present evidence of a significant bias of thermal seed particle injection at small shock-normal angles. We show that downstream isotropisation methods affect the θBn-dependence of this result. We show a non-negligible effect caused by the crossshock potential, and that the effect of downstream cross-field diffusion is highly dependent on boundary definitions. Conclusions. Our results show that for Monte Carlo simulations of coronal shock acceleration a full distribution function assessment with downstream isotropisation through scatterings is necessary to realistically model particle injection. Based on our results, seed particle injection at quasi-parallel coronal shocks can result in significant acceleration efficiency, especially when combined with varying field-line geometry

    Width distribution of contact lines on a disordered substrate

    Full text link
    We have studied the roughness of a contact line of a liquid meniscus on a disordered substrate by measuring its width distribution. The comparison between the measured width distribution and the width distribution calculated in previous works, extended here to the case of open boundary conditions, confirms that the Joanny-de Gennes model is not sufficient to describe the dynamics of contact lines at the depinning threshold. This conclusion is in agreement with recent measurements which determine the roughness exponent by extrapolation to large system sizes.Comment: 4 pages, 3 figure
    • …
    corecore