1,419 research outputs found
On the General Kerr/CFT Correspondence in Arbitrary Dimensions
We study conformal symmetries on the horizon of a general stationary and
axisymmetric black hole. We find that there exist physically reasonable
boundary conditions that uniquely determine a set of symmetry generators, which
form one copy of the Virasoro algebra. For extremal black holes, Cardy's
formula reproduces exactly the Bekenstein-Hawking entropy.Comment: 17 page
The Entropy for General Extremal Black Holes
We use the Kerr/CFT correspondence to calculate the entropy for all known
extremal stationary and axisymmetric black holes. This is done with the help of
two ansatzs that are general enough to cover all such known solutions.
Considering only the contribution from the Einstein-Hilbert action to the
central charge(s), we find that the entropy obtained by using Cardy's formula
exactly matches with the Bekenstein-Hawking entropy.Comment: Minor corrections, section 5 refined, references added
Displacements analysis of self-excited vibrations in turning
The actual research deals with determining by a new protocol the necessary
parameters considering a three-dimensional model to simulate in a realistic way
the turning process on machine tool. This paper is dedicated to the
experimental displacements analysis of the block tool / block workpiece with
self-excited vibrations. In connexion with turning process, the self-excited
vibrations domain is obtained starting from spectra of two accelerometers. The
existence of a displacements plane attached to the tool edge point is revealed.
This plane proves to be inclined compared to the machines tool axes. We
establish that the tool tip point describes an ellipse. This ellipse is very
small and can be considered as a small straight line segment for the stable
cutting process (without vibrations). In unstable mode (with vibrations) the
ellipse of displacements is really more visible. A difference in phase occurs
between the tool tip displacements on the radial direction and on the cutting
one. The feed motion direction and the cutting one are almost in phase. The
values of the long and small ellipse axes (and their ratio) shows that these
sizes are increasing with the feed rate value. The axis that goes through the
stiffness center and the tool tip represents the maximum stiffness direction.
The maximum (resp. minimum) stiffness axis of the tool is perpendicular to the
large (resp. small) ellipse displacements axis. FFT analysis of the
accelerometers signals allows to reach several important parameters and
establish coherent correlations between tool tip displacements and the static -
elastic characteristics of the machine tool components tested
Holographic Dual of Linear Dilaton Black Hole in Einstein-Maxwell-Dilaton-Axion Gravity
Motivated by the recently proposed Kerr/CFT correspondence, we investigate
the holographic dual of the extremal and non-extremal rotating linear dilaton
black hole in Einstein-Maxwell-Dilaton-Axion Gravity. For the case of extremal
black hole, by imposing the appropriate boundary condition at spatial infinity
of the near horizon extremal geometry, the Virasoro algebra of conserved
charges associated with the asymptotic symmetry group is obtained. It is shown
that the microscopic entropy of the dual conformal field given by Cardy formula
exactly agrees with Bekenstein-Hawking entropy of extremal black hole. Then, by
rewriting the wave equation of massless scalar field with sufficient low energy
as the SL(2, R)SL(2, R) Casimir operator, we find the hidden
conformal symmetry of the non-extremal linear dilaton black hole, which implies
that the non-extremal rotating linear dilaton black hole is holographically
dual to a two dimensional conformal field theory with the non-zero left and
right temperatures. Furthermore, it is shown that the entropy of non-extremal
black hole can be reproduced by using Cardy formula.Comment: 15 pages, no figure, published versio
A massive proto-cluster of galaxies at a redshift of z {\approx} 5.3
Massive clusters of galaxies have been found as early as 3.9 Billion years
(z=1.62) after the Big Bang containing stars that formed at even earlier
epochs. Cosmological simulations using the current cold dark matter paradigm
predict these systems should descend from "proto-clusters" - early
over-densities of massive galaxies that merge hierarchically to form a cluster.
These proto-cluster regions themselves are built-up hierarchically and so are
expected to contain extremely massive galaxies which can be observed as
luminous quasars and starbursts. However, observational evidence for this
scenario is sparse due to the fact that high-redshift proto-clusters are rare
and difficult to observe. Here we report a proto-cluster region 1 billion years
(z=5.3) after the Big Bang. This cluster of massive galaxies extends over >13
Mega-parsecs, contains a luminous quasar as well as a system rich in molecular
gas. These massive galaxies place a lower limit of >4x10^11 solar masses of
dark and luminous matter in this region consistent with that expected from
cosmological simulations for the earliest galaxy clusters.Comment: Accepted to Nature, 16 Pages, 6 figure
The RN/CFT Correspondence Revisited
We reconsidered the quantum gravity description of the near horizon extremal
Reissner-Nordstr{\o}m black hole in the viewpoint of the AdS/CFT
correspondence. We found that, for pure electric case, the right moving central
charge of dual 1D CFT is which is different from the previous result of left moving sector obtained by warped AdS/CFT description. We
discussed the discrepancy in these two approaches and examined novel properties
of our result.Comment: revtex4, 16 pages, sign mistakes corrected, references include
Allelic based gene-gene interactions in rheumatoid arthritis
The detection of gene-gene interaction is an important approach to understand the etiology of rheumatoid arthritis (RA). The goal of this study is to identify gene-gene interaction of SNPs at the allelic level contributing to RA using real data sets (Problem 1) of North American Rheumatoid Arthritis Consortium (NARAC) provided by Genetic Analysis Workshop 16 (GAW16). We applied our novel method that can detect the interaction by a definition of nonrandom association of alleles that occurs when the contribution to RA of a particular allele inherited in one gene depends on a particular allele inherited at other unlinked genes. Starting with 639 single-nucleotide polymorphisms (SNPs) from 26 candidate genes, we identified ten two-way interacting genes and one case of three-way interacting genes. SNP rs2476601 on PTPN22 interacts with rs2306772 on SLC22A4, which interacts with rs881372 on TRAF1 and rs2900180 on C5, respectively. SNP rs2900180 on C5 interacts with rs2242720 on RUNX1, which interacts with rs881375 on TRAF1. Furthermore, rs2476601 on PTPN22 also interacts with three SNPs (rs2905325, rs1476482, and rs2106549) in linkage disequilibrium (LD) on IL6. The other three SNPs (rs2961280, rs2961283, and rs2905308) in LD on IL6 interact with two SNPs (rs477515 and rs2516049) on HLA-DRB1. SNPs rs660895 and rs532098 on HLA-DRB1 interact with rs2834779 and four SNPs in LD on RUNX1. Three-way interacting genes of rs10229203 on IL6, rs4816502 on RUNX1, and rs10818500 on C5 were also detected
Hidden Conformal Symmetry of the Reissner-Nordstr{\o}m Black Holes
Motivated by recent progresses in the holographic descriptions of the Kerr
and Reissner-Nordstr{\o}m (RN) black holes, we explore the hidden conformal
symmetry of nonextremal uplifted 5D RN black hole by studying the near horizon
wave equation of a massless scalar field propagating in this background.
Similar to the Kerr black hole case, this hidden symmetry is broken by the
periodicity of the associated angle coordinate in the background geometry, but
the results somehow testify the dual CFT description of the nonextremal RN
black holes. The duality is further supported by matching of the entropies and
absorption cross sections calculated from both CFT and gravity sides.Comment: 14 pages, no figur
Holographic Duals of Near-extremal Reissner-Nordstrom Black Holes
We consider the description of
Reissner-Nordstr{\o}m black holes by studying their uplifted counterparts in
five dimensions. Assuming a natural size of the extra dimension, the near
horizon geometries for the extremal limit are exactly . We compute the scattering amplitude of a scalar field, with a
mode near threshold of frequency and extra dimensional momentum, by a near
extremal uplifted black hole. The absorption cross section agrees with the two
point function of the CFT dual to the scalar field.Comment: reference added, improper statements corrected, 17 pages, no figure
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