6,689 research outputs found

    Neuron impairment or loss in brain may be responsible for type 2 diabetes and essential hypertension

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    Type 2 diabetes and essential hypertension are both very common chronic diseases. Type 2 diabetes is often associated with hypertension, but the exact causes of them are unknown. Here, based on recent investigations, we will look at the pathogenesis of these two diseases in a new light

    Constraints on the Asymptotic Baryon Fractions of Galaxy Clusters at Large Radii

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    While X-ray measurements have so far revealed an increase in the volume-averaged baryon fractions fb(r)f_b(r) of galaxy clusters with cluster radii rr, fb(r)f_b(r) should asymptotically reach a universal value fb(∞)=fbf_b(\infty)=f_b, provided that clusters are representative of the Universe. In the framework of hydrostatic equilibrium for intracluster gas, we have derived the necessary conditions for fb(∞)=fbf_b(\infty)=f_b: The X-ray surface brightness profile described by the β\beta model and the temperature profile approximated by the polytropic model should satisfy γ≈2(1−1/3β)\gamma\approx2(1-1/3\beta) and γ≈1+1/3β\gamma\approx1+1/3\beta for β1\beta1, respectively, which sets a stringent limit to the polytropic index: γ<4/3\gamma<4/3. In particular, a mildly increasing temperature with radius is required if the observationally fitted β\beta parameter is in the range 1/3<β<2/31/3<\beta<2/3. It is likely that a reliable determination of the universal baryon fraction can be achieved in the small β\beta clusters because the disagreement between the exact and asymptotic baryon fractions for clusters with β>2/3\beta>2/3 breaks down at rather large radii (\ga30r_c) where hydrostatic equilibrium has probably become inapplicable. We further explore how to obtain the asymptotic value fb(∞)f_b(\infty) of baryon fraction from the X-ray measurement made primarily over the finite central region of a cluster. We demonstrate our method using a sample of 19 strong lensing clusters, which enables us to place a useful constraint on fb(∞)f_b(\infty): 0.094±0.035≤fb(∞)≤0.41±0.180.094\pm0.035 \leq f_b(\infty) \leq 0.41\pm0.18. An optimal estimate of fb(∞)f_b(\infty) based on three cooling flow clusters with β=0.142±0.007\beta = 0.142\pm0.007 or ΩM=0.35±0.09\Omega_M = 0.35\pm0.09.Comment: 6 pages + 4 figures; accepted for publication in MNRA

    Multiple Fermi pockets revealed by Shubnikov-de Haas oscillations in WTe2

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    We use magneto-transport measurements to investigate the electronic structure of WTe2 single crystals. A non-saturating and parabolic magnetoresistance is observed in the temperature range between 2.5 to 200 K and magnetic fields up to 8 T. Shubnikov - de Haas oscillations with beating patterns are observed. The fast Fourier transform of the SdH oscillations reveals three oscillation frequencies, corresponding to three pairs of Fermi pockets with comparable effective masses , m* ~ 0.31 me. By fitting the Hall resistivity, we infer the presence of one pair of electron pockets and two pairs of hole pockets, together with nearly perfect compensation of the electron-hole carrier concentration. These magnetotransport measurements reveal the complex electronic structure in WTe2, explaining the nonsaturating magnetoresistance.Comment: Submitted to journal on 1 April, 2015, 4 Figure
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