5,337 research outputs found
-dimensional charged Anti-de-Sitter black holes in gravity
We present a -dimensional charged Anti-de-Sitter black hole solutions in
gravity, where and . These solutions are
characterized by flat or cylindrical horizons. The interesting feature of these
solutions is the existence of inseparable electric monopole and quadrupole
terms in the potential which share related momenta, in contrast with most of
the known charged black hole solutions in General Relativity and its
extensions. Furthermore, these solutions have curvature singularities which are
milder than those of the known charged black hole solutions in General
Relativity and Teleparallel Gravity. This feature can be shown by calculating
some invariants of curvature and torsion tensors. Furthermore, we calculate the
total energy of these black holes using the energy-momentum tensor. Finally, we
show that these charged black hole solutions violate the first law of
thermodynamics in agreement with previous results.Comment: 11 Pages, will appear in JHE
Rotating charged AdS solutions in quadratic gravity
We present a class of asymptotically anti-de Sitter charged rotating black
hole solutions in gravity in -dimensions, where . These solutions are nontrivial extensions of the solutions presented in
\cite{Lemos:1994xp} and \cite{Awad:2002cz} in the context of general
relativity. They are characterized by cylindrical, toroidal or flat horizons,
depending on global identifications. The static charged black hole
configurations obtained in \cite{Awad:2017tyz} are recovered as special cases
when the rotation parameters vanish. Similar to \cite{Awad:2017tyz} the static
black holes solutions have two different electric multipole terms in the
potential with related moments. Furthermore, these solutions have milder
singularities compared to their general relativity counterparts. Using the
conserved charges expressions obtained in \cite{Ulhoa:2013gca} and
\cite{Maluf:2008ug} we calculate the total mass/energy and the angular momentum
of these solutions.Comment: 11 pages, Version accepted in EPJ
Underdetermined blind source separation based on Fuzzy C-Means and Semi-Nonnegative Matrix Factorization
Conventional blind source separation is based on over-determined with more sensors than sources but the underdetermined is a challenging case and more convenient to actual situation. Non-negative Matrix Factorization (NMF) has been widely applied to Blind Source Separation (BSS) problems. However, the separation results are sensitive to the initialization of parameters of NMF. Avoiding the subjectivity of choosing parameters, we used the Fuzzy C-Means (FCM) clustering technique to estimate the mixing matrix and to reduce the requirement for sparsity. Also, decreasing the constraints is regarded in this paper by using Semi-NMF. In this paper we propose a new two-step algorithm in order to solve the underdetermined blind source separation. We show how to combine the FCM clustering technique with the gradient-based NMF with the multi-layer technique. The simulation results show that our proposed algorithm can separate the source signals with high signal-to-noise ratio and quite low cost time compared with some algorithms
Intestinal epithelial responses to Salmonella enterica serovar Enteritidis: Effects on intestinal permeability and ion transport
Salmonella infection of chickens that leads to potential human foodborne salmonellosis continues to be a major concern. Chickens serve as carriers but, in contrast to humans, rarely show any clinical signs including diarrhea. The present investigations aimed to elucidate whether the absence of diarrhea during acute Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) infection may be linked to specific changes in the electrophysiological properties of the chicken gut. Immediately after slaughter, intestinal pieces of the mid-jejunum and cecum of either commercial broiler or specific pathogen-free (SPF) chickens were mounted in Ussing chambers in 2 separate experimental series. Living Salmonella Enteritidis (3 Ă— 109) or Salmonella Enteritidis endotoxin (20 mg/L), or both, were added to the mucosal side for 1 h. In both experimental series, the Salmonella infection decreased the trans-epithelial ion conductance Gt (P < 0.05). In the jejunum of SPF chickens, there was also a marked decrease in net charge transfer across the epithelium, evidenced by decreased short-circuit current (Isc, P < 0.05). Interestingly, the mucosal application of Salmonella endotoxin to the epithelial preparations from jejunum and cecum of SPF chicken had an effect similar to living bacteria. However, the endotoxin had no additional effect on the intestinal function in the presence of bacteria. The decreasing effect of Salmonella and or its endotoxin on Gt could be partly reversed by serosal addition of histamine. To our knowledge, this is the first study to address the functional response of native intestinal epithelium of chicken to an in vitro Salmonella infection. For the first time, it can be reported that intestinal ion permeability of chicken decreases acutely by the presence of Salmonella. This type of response could counteract ion and fluid secretion and may thus, at least in part, explain why chickens do not develop overt diarrhea after Salmonella infection
The optical sensor mote, a novel device for enabling next generation Wireless Sensor Networks
Recent advances in micro-electronics and communications have fuelled research in Wireless Sensor Networks (WSNs). WSNs are a collection of low power, low cost, small form factor devices referred to as sensor motes interconnected in a random manner to establish a network. Despite wide ranging research into a range of applications, significant limitations stand in the way of utilizing WSNs to monitor large scale/area environments. Optical sensing techniques are well suited for monitoring a large variety of environmental variables such as temperature, pressure, humidity, and gas concentrations. However, traditional optical sensing techniques rely on bulky solutions including spectroscopic equipment and fibre based approaches. On the other hand, photonic crystals have caused a revolution in integrated optics as they allow functionalities not possible before; however little has been reported on their use as integrated optical sensors. The research work combines the diverse but related fields of WSNs, integrated optics, and Photonic Crystals. A novel platform, the optical sensor mote, is proposed and its key building blocks are experimentally demonstrated as a feasibility study. Specifically, multi-gas sensors based on the slow light phenomenon in photonic crystal waveguides are theoretically and experimentally demonstrated. These sensors can sense multiple gases without the need of any physical changes. They can also be integrated with electronics to yield an optical sensor mote of small form factor which is stable, multi-functional, and cost-effective. The optical sensor mote represents a significant step towards enabling the wide spread use of WSNs to monitor large scale/area environments and providing a highly integrated mote platform amenable to mass production and providing multi-functions.Recent advances in micro-electronics and communications have fuelled research in Wireless Sensor Networks (WSNs). WSNs are a collection of low power, low cost, small form factor devices referred to as sensor motes interconnected in a random manner to establish a network. Despite wide ranging research into a range of applications, significant limitations stand in the way of utilizing WSNs to monitor large scale/area environments. Optical sensing techniques are well suited for monitoring a large variety of environmental variables such as temperature, pressure, humidity, and gas concentrations. However, traditional optical sensing techniques rely on bulky solutions including spectroscopic equipment and fibre based approaches. On the other hand, photonic crystals have caused a revolution in integrated optics as they allow functionalities not possible before; however little has been reported on their use as integrated optical sensors. The research work combines the diverse but related fields of WSNs, integrated optics, and Photonic Crystals. A novel platform, the optical sensor mote, is proposed and its key building blocks are experimentally demonstrated as a feasibility study. Specifically, multi-gas sensors based on the slow light phenomenon in photonic crystal waveguides are theoretically and experimentally demonstrated. These sensors can sense multiple gases without the need of any physical changes. They can also be integrated with electronics to yield an optical sensor mote of small form factor which is stable, multi-functional, and cost-effective. The optical sensor mote represents a significant step towards enabling the wide spread use of WSNs to monitor large scale/area environments and providing a highly integrated mote platform amenable to mass production and providing multi-functions
Scale Invariance and the AdS/CFT Correspondence
Using the AdS/CFT correspondence, we show that the Anti-de Sitter (AdS)
rotating (Kerr) black holes in five and seven dimensions provide us with
examples of non-trivial field theories which are scale, but not conformally
invariant. This is demonstrated by our computation of the actions and the
stress-energy tensors of the four and six dimensional field theories residing
on the boundary of these Kerr-AdS black holes spacetimes.Comment: 3 pages. LaTeX, IJMP style. Contribution to proceedings of DPF 2000,
held at Ohio State
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