1,641 research outputs found

    The Orbital Structure of Dark Matter Halos with Gas

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    With the success of the Chandra and XMM missions and the maturation of gravitational lensing techniques, powerful constraints on the orbital structure of cluster dark matter halos are possible. I show that the X-ray emissivity and mass of a galaxy cluster uniquely specify the anisotropy and velocity dispersion profiles of its dark matter halo. I consider hydrostatic as well as cooling flow scenarios, and apply the formalism to the lensing cluster CL0024+16 and the cooling flow cluster Abell 2199. In both cases, the model predicts a parameter-free velocity dispersion profile that is consistent with independent optical redshift surveys of the clusters.Comment: 17 pages, 12 figures; to appear in the Astrophysical Journa

    Impact of loss on the wave dynamics in photonic waveguide lattices

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    We analyze the impact of loss in lattices of coupled optical waveguides and find that in such case, the hopping between adjacent waveguides is necessarily complex. This results not only in a transition of the light spreading from ballistic to diffusive, but also in a new kind of diffraction that is caused by loss dispersion. We prove our theoretical results with experimental observations.Comment: Accepted for publication in PRL, 5+8 pages (Paper + Supplemental material), 4 figure

    The Nehari Manifold for p-Laplacian Equation with Dirichlet Boundary Condition

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    The Nehari manifold for the equation −∆pu(x) = λu(x)|u(x)|p−2 + b(x)|u(x)|γ−2u(x) for x ∈ Ω together with Dirichlet boundary condition is investigated in the case where 0 < γ < p. Exploiting the relationship between the Nehari manifold and fibrering maps (i.e., maps of the form of t → J(tu) where J is the Euler functional associated with the equation), we discuss how the Nehari manifold changes as λ changes, and show how existence results for positive solutions of the equation are linked to the properties of Nehari manifold

    Microencapsulation of saffron petal anthocyanins with cress seed gum compared with Arabic gum through freeze drying

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    In this research, encapsulation efficiency of cress seed gum (CSG) as a native hydrocolloid was compared with Arabic gum (AG) and maltodextrin (dextrose equivalent of 20 (M20), and 7 (M7)) for saffron (Crocus sativus) petal's extract by freeze drying method. Combinations of CSG-M20, AG-M20, and M7-M20 with ratios of 50:50 and M20 alone (100%) were used as wall materials. A mixture of 1:5 (based on dry matter) between core (concentrated anthocyanin extract of saffron petal) and wall materials were freeze dried and stability of encapsulated anthocyanins along with color parameters (a∗, b∗, L∗, C, H° and TCD) of final powders were measured during 10 weeks of storage (at 35 °C as an accelerated method). Total anthocyanins were determined through pH differential method every week. Four prepared formulations of encapsulated powders didn't show any significant differences (P > 0.01) in terms of total anthocyanin content measured immediately after production and after 10 weeks storage. AG-M20 mixture and M20 alone showed the highest and lowest TCD, respectively. The mixture of CSG-M20 in comparison with AG-M20 and M20 had the same protecting effect (P < 0.01) but showed a relatively high TCD (9.33). © 2015 Elsevier Ltd. All rights reserved

    A novel method to design variable gain amplifier

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    A novel method to design of Variable gain Amplifiers (VGAs) is proposed. A low power VGA with wide range of gain variation and appropriate bandwidth using new technique is presented in this paper. Moreover, the suggested circuit is simulated in whole process corners and different temperatures in the region of -50 to +70 ºC. The circuit has been designed in a typical 0.35μm CMOS process with a power supply of 3.3V, and simulated by HSPICE software using level 49 parameters (BSIM3v3).Keywords: variable gain amplifier; Operational Transconductance Amplifier; wide gain range; low power; unity gain bandwidt

    Relationship between aerobic and anaerobic power, and Special Judo Fitness Test (SJFT) in elite Iranian male judokas

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    Introduction The purpose of this study was to assess the relationship between aerobic and anaerobic power, and special judo fitness test in elite male judokas. Method Nineteen elite Judokas [age 24.3 (3.1) yr, height 1.78 (.06) m, body mass 76.4 (11.2) kg, body mass index 20.2 (3.6) kg·m−2 and body fat 11.0 (1.8)%] performed a graded exercise test in treadmill, the Wingate anaerobic test for arms and the special judo fitness test. The graded exercise test in treadmill estimated maximal oxygen uptake (VO2max) and the Wingate anaerobic test assessed peak and mean power, descriptors of short-term power output and local muscular endurance respectively. Results The index of special judo fitness test was in inverse direct relationship with VO2max (r = -.87, p < .01), peak power (r = -.74, p < .01) and mean power (r = -.62, p < .05). Discussion Based on these findings, it was showed that the special judo fitness test is a field test that describes chiefly aerobic power, and in a lesser degree short-term power output and local muscular fatigue. Therefore, its further use from judo coaches and fitness trainers as a measure to monitor aerobic power is recommended, and the need for a field test that will describe anaerobic power is highlighted

    Evidence for Non-Hydrostatic Gas from the Cluster X-ray to Lensing Mass Ratio

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    Using a uniform analysis procedure, we measure spatially resolved weak gravitational lensing and hydrostatic X-ray masses for a sample of 18 clusters of galaxies. We find a radial trend in the X-ray to lensing mass ratio: at r2500 we obtain a ratio MX/ML=1.03+/-0.07 which decreases to MX/ML=0.78+/-0.09 at r500. This difference is significant at 3 sigma once we account for correlations between the measurements. We show that correcting the lensing mass for excess correlated structure outside the virial radius slightly reduces, but does not eliminate this trend. An X-ray mass underestimate, perhaps due to nonthermal pressure support, can explain the residual trend. The trend is not correlated with the presence or absence of a cool core. We also examine the cluster gas fraction and find no correlation with ML, an important result for techniques that aim to determine cosmological parameters using the gas fraction.Comment: 8 pages, minor modifications, accepted for publication in MNRA
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