556 research outputs found

    A Maxwell-vector p-wave holographic superconductor in a particular background AdS black hole metric

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    We study the p-wave holographic superconductor for AdS black holes with planar event horizon topology for a particular Lovelock gravity, in which the action is characterized by a self-interacting scalar field nonminimally coupled to the gravity theory which is labeled by an integer kk. As the Lovelock theory of gravity is the most general metric theory of gravity based on the fundamental assumptions of general relativity, it is a desirable theory to describe the higher dimensional spacetime geometry. The present work is devoted to studying the properties of the p-wave holographic superconductor by including a Maxwell field which nonminimally couples to a complex vector field in a higher dimensional background metric. In the probe limit, we find that the critical temperature decreases with the increase of the index kk of the background black hole metric, which shows that a larger kk makes it harder for the condensation to form. We also observe that the index kk affects the conductivity and the gap frequency of the holographic superconductors.Comment: 14 pages, 6 figure

    New bounds for bb-Symbol Distances of Matrix Product Codes

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    Matrix product codes are generalizations of some well-known constructions of codes, such as Reed-Muller codes, [u+v,u−v][u+v,u-v]-construction, etc. Recently, a bound for the symbol-pair distance of a matrix product code was given in \cite{LEL}, and new families of MDS symbol-pair codes were constructed by using this bound. In this paper, we generalize this bound to the bb-symbol distance of a matrix product code and determine all minimum bb-symbol distances of Reed-Muller codes. We also give a bound for the minimum bb-symbol distance of codes obtained from the [u+v,u−v][u+v,u-v]-construction, and use this bound to construct some [2n,2n−2]q[2n,2n-2]_q-linear bb-symbol almost MDS codes with arbitrary length. All the minimum bb-symbol distances of [n,n−1]q[n,n-1]_q-linear codes and [n,n−2]q[n,n-2]_q-linear codes for 1≤b≤n1\leq b\leq n are determined. Some examples are presented to illustrate these results

    Refractive index in generalized superconductors with Born-Infeld electrodynamics

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    We investigate, in the probe limit, the negative refraction in the generalized superconductors with the Born-Infeld electrodynamics. We observe that the system has a negative Depine-Lakhtakia index in the superconducting phase at small frequencies and the greater the Born-Infeld corrections the larger the range of frequencies or the range of temperatures for which the negative refraction occurs. Furthermore, we find that the tunable Born-Infeld parameter can be used to improve the propagation of light in the holographic setup. Our analysis indicates that the Born-Infeld electrodynamics plays an important role in determining the optical properties of the boundary theory.Comment: 13 pages, 6 figure

    A RFID-Based Monitoring System for Characterization of Perching Behaviors of Individual Poultry

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    Perching is a natural behavior of poultry. However, it is difficult to distinguish individual birds in a large group in order to relate perching behavior to health condition or productivity. To enable such research, this study developed and validated a radio frequency identification (RFID)-based automated perching monitoring system (APMS) for characterizing individual perching behaviors of group-housed poultry. The APMS consisted of a RFID module, a load cell module, and a round wooden perch. The RFID module was comprised of a high-frequency RFID reader, three customized rectangular antennas, and multiple RFID transponders. The load cell module was comprised of a data acquisition system and two load cells supporting the two ends of the perch. Daily number of perch visits (PV) and perching duration (PD) of individual birds were used to delineate perching behavior. Three identical experimental pens, five hens per pen, were equipped with the monitoring system. Two RFID transponders were attached to each hen (one per leg) and a distinct color was marked on the bird‘s head for video or visual identification. Performance of the APMS was validated by comparing the system outputs with manual observation/labeling over an entire day. Sensitivity and specificity of the system were shown to improve from 97.77% and 99.88%, respectively, when using only the RFID module, to 99.83% and 99.93%, respectively, when incorporating weight information from the load cell module. This study revealed that the APMS has an excellent performance in measuring perching behaviors of individual birds in a group. The APMS offers great potentials for delineating differences in perching behavior among hens with different social status or health conditions in a group setting
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