55 research outputs found

    Quantifying the effects of acute hypoxic exposure on exercise performance and capacity: A systematic review and meta-regression

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    Objective: To quantify the effects of acute hypoxic exposure on exercise capacity and performance, which includes continuous and intermittent forms of exercise. Design: A systematic review was conducted with a three-level mixed effects meta-regression. The ratio of means method was used to evaluate main effects and moderators providing practical interpretations with percentage change. Data Sources: A systemic search was performed using 3 databases (Google scholar, PubMed and SPORTDiscus). Eligibility criteria for selecting studies: Inclusion was restricted to investigations that assessed exercise performance (time trials, sprint, and intermittent exercise tests) and capacity (time to exhaustion test (TTE)) with acute hypoxic (< 24 hrs) exposure and a normoxic comparator. Results: Eighty-two outcomes from 53 studies (N = 798) were included in this review. The results show an overall reduction in exercise performance/capacity -17.8 ± 3.9% (95% CI -22.8% to -11.0%), which was significantly moderated by -6.5 ± 0.9% per 1000 m altitude elevation (95% CI -8.2% to -4.8%) and oxygen saturation (-2.0 ± 0.4% 95% CI -2.9% to -1.2%). Time trial (-16.2 ± 4.3%; 95% CI -22.9% to -9%) and TTE (-44.5 ± 6.9%; 95% CI -51.3% to -36.7%) elicited a negative effect, whilst indicating a quadratic relationship between hypoxic magnitude and both TTE and TT performance. Furthermore, exercise < 2-min exhibited no ergolytic effect from acute hypoxia. Summary/ Conclusion: This review highlights the ergolytic effect of acute hypoxic exposure; which is curvilinear for TTE and TT performance with increasing hypoxic levels, but short-duration intermittent and sprint exercise seem to be unaffected

    Spin-Glass State in CuGa2O4\rm CuGa_2O_4

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    Magnetic susceptibility, magnetization, specific heat and positive muon spin relaxation (\musr) measurements have been used to characterize the magnetic ground-state of the spinel compound CuGa2O4\rm CuGa_2O_4. We observe a spin-glass transition of the S=1/2 Cu2+\rm Cu^{2+} spins below Tf=2.5K\rm T_f=2.5K characterized by a cusp in the susceptibility curve which suppressed when a magnetic field is applied. We show that the magnetization of CuGa2O4\rm CuGa_2O_4 depends on the magnetic histo Well below Tf\rm T_f, the muon signal resembles the dynamical Kubo-Toyabe expression reflecting that the spin freezing process in CuGa2O4\rm CuGa_2O_4 results Gaussian distribution of the magnetic moments. By means of Monte-Carlo simulati we obtain the relevant exchange integrals between the Cu2+\rm Cu^{2+} spins in this compound.Comment: 6 pages, 16 figure

    Cold Gas in Cluster Cores

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    I review the literature's census of the cold gas in clusters of galaxies. Cold gas here is defined as the gas that is cooler than X-ray emitting temperatures (~10^7 K) and is not in stars. I present new Spitzer IRAC and MIPS observations of Abell 2597 (PI: Sparks) that reveal significant amounts of warm dust and star formation at the level of 5 solar masses per year. This rate is inconsistent with the mass cooling rate of 20 +/- 5 solar masses per year inferred from a FUSE [OVI] detection.Comment: 10 pages, conference proceeding

    Nine months of combined training improves ex vivo skeletal muscle metabolism in individuals with type 2 diabetes

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    Context: Type 2 diabetes (T2D) has features of disordered lipid and glucose metabolism, due in part to reduced mitochondrial content. Objective: Our objective was to investigate effects of different types of exercise on mitochondrial content and substrate oxidation in individuals with T2D (ancillary study of the randomized controlled trial Health Benefits of Aerobic and Resistance Training in Individuals with Type 2 Diabetes, HART-D). Intervention: T2D individuals were randomized to aerobictraining (AT, n = 12), resistance training (RT, n = 18), combination training(ATRT, n = 12), or nonexercise control (n = 10). Blooddraws, peakoxygen consumption tests, dual-energy x-ray absorptiometry scans and muscle biopsies of vastus lateralis were performed before and after 9 months. Ex vivo substrate oxidations ((CO2)-C-14), mitochondrial content, and enzyme activities were measured. Glycated hemoglobin A(1c) and free fatty acids were also determined. Results: Mitochondrial content increased after RT and ATRT. Octanoate oxidation increased after AT and ATRT, whereas palmitate, pyruvate, and acetate oxidations increased in all exercise groups. Exercise-induced responses in mitochondrial DNA were associated with improvements in peak oxygen consumption, beta-hydroxyacyl-coenzyme A dehydrogenase activity, and palmitate oxidation. Conclusions: Nine months of AT and RT significantly improved most aspects of skeletal muscle mitochondrial content and substrate oxidation, whereas the combination improved all aspects. These exercise responses were associated with clinical improvements, indicating that long-term training, especially combination, is an effective lifestyle therapy for individuals with T2D by way of improving muscle substrate metabolism. (J Clin Endocrinol Metab 98: 1694-1702, 2013

    EVN and MERLIN Observations of the FR 1 Radio Galaxy 3C 264

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    al 5 GHz radio source component [4]. NGC 3862 also contains an oval region of line-emitting gas of ¸6.3 arcsec in extent, centered on the galaxy nucleus, with its major axis roughly perpendicular to the radio source ejection axis [1]. A bright optical jet, with a length of ¸0.65 arcsec, was discovered with the Hubble Space Telescope (HST) [3]. 1 The author wishes to acknowledge support for this research by the European Union under contract CHGECT920011. Preprint submitted to Elsevier Preprint 26 February The radio structure of 3C 264 presents, at arc-second scales, a head-tailed morphology [5], with a prominent core and a wiggled jet extending toward the northeast. The magnetic field appears parallel to the jet axis in the proximity of the core, becoming perpendicular at an angular distance of ¸3 arcsec. The flux density of the VLA core is ¸260 mJy. Flux density variability of the core has not bee
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