1,400 research outputs found

    Risk stratification of cardiac arrhythmias and sudden cardiac death in type 2 diabetes mellitus patients receiving insulin therapy: A population-based cohort study

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    Introduction Metabolic abnormalities may exacerbate the risk of adverse outcomes in patients with type 2 diabetes mellitus. The present study aims to assess the predictive value of HbA1c and lipid variability on the risks of sudden cardiac death (SCD) and incident atrial fibrillation (AF). Methods The retrospective observational study consists of type 2 diabetic patients prescribed with insulin, who went to publicly funded clinics and hospitals in Hong Kong between January 1, 2009 and December 31, 2009. Variability in total cholesterol, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), triglyceride, and HbA1c were assessed through their SD and coefficient of variation. The primary outcomes were incident (1) ventricular tachycardia/ventricular fibrillation, actual or aborted SCD and (2) AF. Results A total of 23 329 patients (mean ± SD age: 64 ± 14 years old; 51% male; mean HbA1c 8.6 ± 1.3%) were included. On multivariable analysis, HbA1c, total cholesterol, LDL-C and triglyceride variability were found to be predictors of SCD (p < .05). Conclusion HbA1c and lipid variability were predictive of SCD. Therefore, poor glucose control and variability in lipid parameters in diabetic patients are associated with aborted or actual SCD. These observations suggest the need to re-evaluate the extent of glycemic control required for outcome optimization

    HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation

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    We present the results of a comparative study of HI narrow self-absorption (HINSA), OH, 13CO, and C18O in five dark clouds. The HINSA follows the distribution of the emission of the carbon monoxide isotopologues, and has a characteristic size close to that of 13CO. This confirms that the HINSA is produced by cold HI which is well mixed with molecular gas in well-shielded regions. The ratio of the atomic hydrogen density to total proton density for these sources is 5 to 27 x 10^{-4}. Using cloud temperatures and the density of HI, we set an upper limit to the cosmic ray ionization rate of 10^{-16} s^{-1}. Comparison of observed and modeled fractional HI abundances indicates ages for these clouds to be 10^{6.5} to 10^{7} yr. The low values of the HI density we have determined make it certain that the time scale for evolution from an atomic to an almost entirely molecular phase, must be a minimum of several million years. This clearly sets a lower limit to the overall time scale for star formation and the lifetime of molecular clouds

    Cosmic-ray propagation in molecular clouds

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    Cosmic-rays constitute the main ionising and heating agent in dense, starless, molecular cloud cores. We reexamine the physical quantities necessary to determine the cosmic-ray ionisation rate (especially the cosmic ray spectrum at E < 1 GeV and the ionisation cross sections), and calculate the ionisation rate as a function of the column density of molecular hydrogen. Available data support the existence of a low-energy component (below about 100 MeV) of cosmic-ray electrons or protons responsible for the ionisation of diffuse and dense clouds. We also compute the attenuation of the cosmic-ray flux rate in a cloud core taking into account magnetic focusing and magnetic mirroring, following the propagation of cosmic rays along flux tubes enclosing different amount of mass and mass-to-flux ratios. We find that mirroring always dominates over focusing, implying a reduction of the cosmic-ray ionisation rate by a factor of 3-4 depending on the position inside the core and the magnetisation of the core.Comment: To appear in "Cosmic Rays in Star-Forming Environments", Proceedings of the 2nd Session of the Sant Cugat Forum on Astrophysics. D. F. Torres and O. Reimer (Editors), 2013, Springer, 25 pages, 11 figure

    The origin of the [C II] emission in the S140 PDRs - new insights from HIFI

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    Using Herschel's HIFI instrument we have observed [C II] along a cut through S140 and high-J transitions of CO and HCO+ at two positions on the cut, corresponding to the externally irradiated ionization front and the embedded massive star forming core IRS1. The HIFI data were combined with available ground-based observations and modeled using the KOSMA-tau model for photon dominated regions. Here we derive the physical conditions in S140 and in particular the origin of [C II] emission around IRS1. We identify three distinct regions of [C II] emission from the cut, one close to the embedded source IRS1, one associated with the ionization front and one further into the cloud. The line emission can be understood in terms of a clumpy model of photon-dominated regions. At the position of IRS1, we identify at least two distinct components contributing to the [C II] emission, one of them a small, hot component, which can possibly be identified with the irradiated outflow walls. This is consistent with the fact that the [C II] peak at IRS1 coincides with shocked H2 emission at the edges of the outflow cavity. We note that previously available observations of IRS1 can be well reproduced by a single-component KOSMA-tau model. Thus it is HIFI's unprecedented spatial and spectral resolution, as well as its sensitivity which has allowed us to uncover an additional hot gas component in the S140 region.Comment: accepted for publication in Astronomy and Astrophysics (HIFI special issue

    Selective Growth of Vertical-aligned ZnO Nanorod Arrays on Si Substrate by Catalyst-free Thermal Evaporation

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    By thermal evaporation of pure ZnO powders, high-density vertical-aligned ZnO nanorod arrays with diameter ranged in 80–250 nm were successfully synthesized on Si substrates covered with ZnO seed layers. It was revealed that the morphology, orientation, crystal, and optical quality of the ZnO nanorod arrays highly depend on the crystal quality of ZnO seed layers, which was confirmed by the characterizations of field-emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and photoluminescence measurements. For ZnO seed layer with wurtzite structure, the ZnO nanorods grew exactly normal to the substrate with perfect wurtzite structure, strong near-band-edge emission, and neglectable deep-level emission. The nanorods synthesized on the polycrystalline ZnO seed layer presented random orientation, wide diameter, and weak deep-level emission. This article provides a C-free and Au-free method for large-scale synthesis of vertical-aligned ZnO nanorod arrays by controlling the crystal quality of the seed layer

    Best practices for fNIRS publications

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    The application of functional near-infrared spectroscopy (fNIRS) in the neurosciences has been expanding over the last 40 years. Today, it is addressing a wide range of applications within different populations and utilizes a great variety of experimental paradigms. With the rapid growth and the diversification of research methods, some inconsistencies are appearing in the way in which methods are presented, which can make the interpretation and replication of studies unnecessarily challenging. The Society for Functional Near-Infrared Spectroscopy has thus been motivated to organize a representative (but not exhaustive) group of leaders in the field to build a consensus on the best practices for describing the methods utilized in fNIRS studies. Our paper has been designed to provide guidelines to help enhance the reliability, repeatability, and traceability of reported fNIRS studies and encourage best practices throughout the community. A checklist is provided to guide authors in the preparation of their manuscripts and to assist reviewers when evaluating fNIRS papers

    Initiation of warfarin is associated with decreased mortality in patients with infective endocarditis: A population-based cohort study.

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    The use of warfarin to prevent thromboembolism in patients with infective endocarditis (IE) remains controversial due to potentially increased bleeding risks. Population-based retrospective cohort study. Patients aged 18 or older and diagnosed with IE in Hong Kong between January 1st, 1997 and August 31st, 2020 were included. Patients with use of any anticoagulant 30 days before IE diagnosis were excluded. Patients initiated on warfarin within 14 days of IE diagnosis and patients without warfarin use were matched for baseline characteristics using 1:1 propensity score matching. Warfarin use within 14 days of IE diagnosis. Patients were followed up to 90 days for the outcomes of ischemic stroke, all-cause mortality, intracranial hemorrhage, and gastrointestinal bleeding. Cox regression was used to determine hazard ratios (HRs) [95 % confidence intervals (CIs)] between treatment groups. Fine-Gray competing risk regression with all-cause mortality as the competing event was performed as a sensitivity analysis. In addition to 90-day analyses, landmark analyses were performed at 30 days of follow-up. The matched cohort consisted of 675 warfarin users (57.0 % male, age 59 ± 16 years) and 675 warfarin non-users (53.5 % male, age 61 ± 19 years). Warfarin users had a 50 % decreased 90-day risk in all-cause mortality (HR:0.50 [0.39-0.65]), without significantly different 90-day risks of ischemic stroke (HR:1.04 [0.70-1.53]), intracranial hemorrhage (HR:1.25 [0.77-2.04]), and gastrointestinal bleeding (HR:1.04 [0.60-1.78]). Thirty-day landmark analysis showed similar results. Competing risk regression showed significantly higher 30-day cumulative incidence of intracranial hemorrhage in warfarin users (sub-HR:3.34 [1.34-8.31]), but not at 90-day (sub-HR:1.63 [0.95-2.81]). Results from Fine-Gray regression were otherwise congruent with those from Cox regression. Warfarin initiated within 14 days of IE diagnosis was associated with significantly decreased risks of mortality but higher risks of intracranial hemorrhage, with similar risks of ischemic stroke and gastrointestinal bleeding, compared with non-use of warfarin with 14 days of IE diagnosis. Question: Is warfarin, initiated within 14 days of a diagnosis of infective endocarditis (IE), efficacious and safe? In this propensity score-matched, population-based, prospective cohort study from Hong Kong, warfarin use within 14 days of IE diagnosis was associated with a 50 % decrease in the risk of all-cause mortality, albeit with higher risk of intracranial hemorrhage, and without significant differences in the risk of ischaemic stroke and gastrointestinal bleeding. Meaning: In patients with IE, warfarin use within 14 days of diagnosis may have mortality benefits, despite increased risks of intracranial hemorrhage. [Abstract copyright: Copyright © 2023. Published by Elsevier Ltd.
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