19,032 research outputs found

    Dietary Vitamin B6 Requirement of Juvenile Grass Carp (Ctenopharyngodon idella)

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    We evaluated the effects of dietary vitamin B6 levels on growth, survival, and serum biochemical parameters in juvenile grass carp (Ctenopharyngodon idella). Fish were fed one of seven purified diets containing 0.12 (control), 1.16, 2.37, 4.82, 9.20, 17.51, or 36.52 mg/kg B6. We observed abnormal swimming behavior in some fish fed the control diet after 17 days. The survival rate (24.44±1.92%) was low in the control group. Supplementation with vitamin B6 resulted in significantly higher (P<0.05) weight gain, specific growth rate, final weight, and weight gain rate. Feed efficiency was significantly lower in the fish fed the control diet than the remaining groups (P<0.05). Dietary vitamin B6 levels had no significant effect on fish body composition or serum albumin and total protein content. Dietary vitamin B6 supplementation caused a decrease in serum triacylglycerol content and an increase in total cholesterol content, high density lipoprotein cholesterol content, and α-amylase activity levels (P<0.05). Broken-line regression analysis of SGR, HDL-C content, and α-AMY activity, showed that the optimum dietary vitamin B6 requirement for juvenile grass carp was 1.13, 3.73, 1.57 mg B6/kg, respectively

    Real Scalar Field Scattering with Polynomial Approximation around Schwarzschild-de Sitter Black-hole

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    As one of the fitting methods, the polynomial approximation is effective to process sophisticated problem. In this paper, we employ this approach to handle the scattering of scalar field around the Schwarzschild-de Sitter black-hole. The complex relationship between tortoise coordinate and radial coordinate is replaced by the approximate polynomial. The Schro¨\ddot{o}dinger-like equation, the real boundary conditions and the polynomial approximation construct a full Sturm-Liouville type problem. Then this boundary value problem can be solved numerically according to two limiting cases: the first one is the Nariai black-hole whose horizons are close to each other, the second one is when the horizons are widely separated. Compared with previous results (Brevik and Tian), the field near the event horizon and cosmological horizon can have a better description.Comment: revtex4 source file, 11 pages, 8 figure

    Fermions tunnelling from the charged dilatonic black holes

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    Kerner and Mann's recent work shows that, for an uncharged and non-rotating black hole, its Hawking temperature can be exactly derived by fermions tunnelling from its horizons. In this paper, our main work is to improve the analysis to deal with charged fermion tunnelling from the general dilatonic black holes, specifically including the charged, spherically symmetric dilatonic black hole, the rotating Einstein-Maxwell-Dilaton-Axion (EMDA) black hole and the rotating Kaluza-Klein (KK) black hole. As a result, the correct Hawking temperatures are well recovered by charged fermions tunnelling from these black holes.Comment: 16 pages, revised version to appear in Class. Quant. Gra

    The First Release of the CSTAR Point Source Catalog from Dome A, Antarctica

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    In 2008 January the 24th Chinese expedition team successfully deployed the Chinese Small Telescope ARray (CSTAR) to DomeA, the highest point on the Antarctic plateau. CSTAR consists of four 14.5cm optical telescopes, each with a different filter (g, r, i and open) and has a 4.5degree x 4.5degree field of view (FOV). It operates robotically as part of the Plateau Observatory, PLATO, with each telescope taking an image every 30 seconds throughout the year whenever it is dark. During 2008, CSTAR #1 performed almost flawlessly, acquiring more than 0.3 million i-band images for a total integration time of 1728 hours during 158 days of observations. For each image taken under good sky conditions, more than 10,000 sources down to 16 mag could be detected. We performed aperture photometry on all the sources in the field to create the catalog described herein. Since CSTAR has a fixed pointing centered on the South Celestial Pole (Dec =-90 degree), all the sources within the FOV of CSTAR were monitored continuously for several months. The photometric catalog can be used for studying any variability in these sources, and for the discovery of transient sources such as supernovae, gamma-ray bursts and minor planets.Comment: 1 latex file and 9 figures The paper is accepted by PAS

    Metamagnetic transition in EuFe2_2As2_2 single crystals

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    We report the measurements of anisotropic magnetization and magnetoresistance on single crystals of EuFe2_2As2_2, a parent compound of ferro-arsenide high-temperature superconductor. Apart from the antiferromagnetic (AFM) spin-density-wave transition at 186 K associated with Fe moments, the compound undergoes another magnetic phase transition at 19 K due to AFM ordering of Eu2+^{2+} spins (J=S=7/2J=S=7/2). The latter AFM state exhibits metamagnetic transition under magnetic fields. Upon applying magnetic field with HcH\parallel c at 2 K, the magnetization increases linearly to 7.0 μB\mu_{B}/f.u. at μ0H\mu_{0}H=1.7 T, then keeps at this value of saturated Eu2+^{2+} moments under higher fields. In the case of HabH\parallel ab, the magnetization increases step-like to 6.6 μB\mu_{B}/f.u. with small magnetic hysteresis. A metamagnetic phase was identified with the saturated moments of 4.4 μB\mu_{B}/f.u. The metamagnetic transition accompanies with negative in-plane magnetoresistance, reflecting the influence of Eu2+^{2+} moments ordering on the electrical conduction of FeAs layers. The results were explained in terms of spin-reorientation and spin-reversal based on an AA-type AFM structure for Eu2+^{2+} spins. The magnetic phase diagram has been established.Comment: 10 pages, 8 figures. accepted for publication in New Journal of Physics as a special issue articl
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