2,263 research outputs found
Emergent Quantum Near-Criticality from Baryonic Black Branes
We find new black 3-brane solutions describing the "conifold gauge theory" at
nonzero temperature and baryonic chemical potential. Of particular interest is
the low-temperature limit where we find a new kind of weakly curved
near-horizon geometry; it is a warped product AdS_2 x R^3 x T^{1,1} with warp
factors that are powers of the logarithm of the AdS radius. Thus, our solution
encodes a new type of emergent quantum near-criticality. We carry out some
stability checks for our solutions. We also set up a consistent ansatz for
baryonic black 2-branes of M-theory that are asymptotic to AdS_4 x Q^{1,1,1}.Comment: 29 pages, 4 figures; v2 discussion of entropy revised, minor changes;
v3 note added, minor improvements, version published in JHE
Explosion Mechanisms of Core-Collapse Supernovae
Supernova theory, numerical and analytic, has made remarkable progress in the
past decade. This progress was made possible by more sophisticated simulation
tools, especially for neutrino transport, improved microphysics, and deeper
insights into the role of hydrodynamic instabilities. Violent, large-scale
nonradial mass motions are generic in supernova cores. The neutrino-heating
mechanism, aided by nonradial flows, drives explosions, albeit low-energy ones,
of ONeMg-core and some Fe-core progenitors. The characteristics of the neutrino
emission from new-born neutron stars were revised, new features of the
gravitational-wave signals were discovered, our notion of supernova
nucleosynthesis was shattered, and our understanding of pulsar kicks and
explosion asymmetries was significantly improved. But simulations also suggest
that neutrino-powered explosions might not explain the most energetic
supernovae and hypernovae, which seem to demand magnetorotational driving. Now
that modeling is being advanced from two to three dimensions, more realism, new
perspectives, and hopefully answers to long-standing questions are coming into
reach.Comment: 35 pages, 11 figures (29 eps files; high-quality versions can be
obtained upon request); accepted by Annual Review of Nuclear and Particle
Scienc
On The Phase Structure and Thermodynamic Geometry of R-Charged Black Holes
We study the phase structure and equilibrium state space geometry of
R-charged black holes in , 4 and 7 and the corresponding rotating ,
and branes. For various charge configurations of the compact black
holes in the canonical ensemble we demonstrate new liquid-gas like phase
coexistence behaviour culminating in second order critical points. The critical
exponents turn out to be the same as that of four dimensional asymptotically
AdS black holes in Einstein Maxwell theory. We further establish that the
regions of stability for R-charged black holes are, in some cases, more
constrained than is currently believed, due to properties of some of the
response coefficients. The equilibrium state space scalar curvature is
calculated for various charge configurations, both for the case of compact as
well as flat horizons and its asymptotic behaviour with temperature is
established.Comment: 1 + 33 pages, LaTeX, 25 figures. References adde
Thermodynamics of string black hole with hyperscaling violation
In this paper, we start with black brane and construct specific space-time
which violates hyperscaling. In order to obtain the string solution we apply
Null-Melvin-Twist and -reduction. By using the difference action method we
study thermodynamics of system to obtain Hawking-Page phase transition. In
order to have hyperscaling violation we need to consider
In that case the free energy is always negative and our solution is thermal
radiation without a black hole. Therefore we find that there is not any
Hawking-Page transition. Also, we discuss the stability of system and all
thermodynamical quantities.Comment: 12 pages. Accepted for publication in EPJ
Supersymmetric Charged Clouds in AdS_5
We consider supersymmetric holographic flows that involve background gauge
fields dual to chemical potentials in the boundary field theory. We use a
consistent truncation of gauged N=8 supergravity in five dimensions and we give
a complete analysis of the supersymmetry conditions for a large family of
flows. We examine how the well-known supersymmetric flow between two fixed
points is modified by the presence of the chemical potentials and this yields a
new, completely smooth, solution that interpolates between two global AdS
spaces of different radii and with different values of the chemical potential.
We also examine some black-hole-like singular flows and a new
non-supersymmetric black hole solution. We comment on the interpretation of our
new solutions in terms of giant gravitons and discuss the implications of our
work for finding black-hole solutions in AdS geometries.Comment: 31 pages, 6 figures; minor corrections, updated reference
The particle number in Galilean holography
Recently, gravity duals for certain Galilean-invariant conformal field
theories have been constructed. In this paper, we point out that the spectrum
of the particle number operator in the examples found so far is not a necessary
consequence of the existence of a gravity dual. We record some progress towards
more realistic spectra. In particular, we construct bulk systems with
asymptotic Schrodinger symmetry and only one extra dimension. In examples, we
find solutions which describe these Schrodinger-symmetric systems at finite
density. A lift to M-theory is used to resolve a curvature singularity. As a
happy byproduct of this analysis, we realize a state which could be called a
holographic Mott insulator.Comment: 29 pages, 1 rudimentary figure; v2: typo in eqn (3.4), added comments
and ref
Thermodynamics of Holographic Defects
Using the AdS/CFT correspondence, we study the thermodynamic properties and
the phase diagram of matter fields on (2+1)-dimensional defects coupled to a
(3+1)-dimensional N=4 SYM "heat bath". Considering a background magnetic field,
(net) quark density, defect "magnitude" and the mass of the
matter, we study the defect contribution to the thermodynamic potentials and
their first and second derivatives to map the phases and study their physical
properties.
We find some features that are qualitatively similar to other systems e.g. in
(3+1) dimensions and a number of features that are particular to the defect
nature, such as its magnetic properties, unexpected properties at T->0 and
finite density; and the finite effects, e.g. a diverging
susceptibility and vanishing density of states at small temperatures, a
physically consistent negative heat capacity and new types of consistent
phases.Comment: 33 pages, 16 figures (jpg and pdf), typos fixed and references added,
final version published in JHE
Role of positron emission tomography-computed tomography in bronchial mucoepidermoid carcinomas: a case series and review of the literature
<p>Abstract</p> <p>Introduction</p> <p>Mucoepidermoid carcinoma of the tracheobronchial tree is rare. Such tumors usually present with signs and symptoms of bronchial obstruction. Histologically, they can be classified as high-grade or low-grade tumors. Experience of imaging these tumors with <sup>18</sup>fluorodeoxyglucose positron emission tomography-computed tomography (<sup>18</sup>F-FDG PET-CT) is limited. We present three cases of this rare tumor, describe the functional imaging results, and review the available literature.</p> <p>Case presentation</p> <p>Three Caucasian patients, two men (21 and 24 years of age) and one woman (14 years of age), with bronchial masses were evaluated by us. All three patients were symptomatic, and underwent a thorough clinical examination, bronchoscopy and biopsy, plain computed tomography, <sup>18</sup>F-FDG PET-CT and <sup>68</sup>Gallium 1,4,7,10-Tetraazacyclododecane-N<sup>I</sup>,N<sup>II</sup>,N<sup>III</sup>,N<sup>IIII</sup>,- tetra acetic acid (D) - Phel<sup>1</sup>-Tyr<sup>3</sup>-octreotide positron emission tomography-computed tomography (<sup>68</sup>Ga-DOTATOC PET-CT). <sup>18</sup>F-FDG PET-CT revealed mild uptake in all three patients, whereas <sup>68</sup>Ga-DOTATOC PET-CT revealed no significant uptake in any patient, making carcinoid tumor unlikely. Results of histopathological examination were consistent with low-grade mucoepidermoid carcinoma in all patients.</p> <p>Conclusion</p> <p>Our study reveals that functional imaging may be helpful in the initial investigation of patients with mucoepidermoid carcinoma. <sup>18</sup>F-FDG PET-CT may have a prognostic relevance by predicting the histopathologic differentiation of the tumor.</p
Thermodynamics of Large N Gauge Theories with Chemical Potentials in a 1/D Expansion
In order to understand thermodynamical properties of N D-branes with chemical
potentials associated with R-symmetry charges, we study a one dimensional large
N gauge theory (bosonic BFSS type model) as a first step. This model is
obtained through a dimensional reduction of a 1+D dimensional SU(N) Yang-Mills
theory and we use a 1/D expansion to investigate the phase structure. We find
three phases in the \mu-T plane. We also show that all the adjoint scalars
condense at large D and obtain a mass dynamically. This dynamical mass protects
our model from the usual perturbative instability of massless scalars in a
non-zero chemical potential. We find that the system is at least meta-stable
for arbitrary large values of the chemical potentials in D \to \infty limit. We
also explore the existence of similar condensation in higher dimensional gauge
theories in a high temperature limit. In 2 and 3 dimensions, the condensation
always happens as in one dimensional case. On the other hand, if the dimension
is higher than 4, there is a critical chemical potential and the condensation
happens only if the chemical potentials are below it.Comment: 37 pages, 4 figures; v2: minor corrections, references added; v3:
minor corrections, to appear in JHE
Acute rejection is associated with antibodies to non-Gal antigens in baboons using Gal-knockout pig kidneys
We transplanted kidneys from α1,3-galactosyltransferase knockout (GalT-KO) pigs into six baboons using two different immunosuppressive regimens, but most of the baboons died from severe acute humoral xenograft rejection. Circulating induced antibodies to non-Gal antigens were markedly elevated at rejection, which mediated strong complement-dependent cytotoxicity against GalT-KO porcine target cells. These data suggest that antibodies to non-Gal antigens will present an additional barrier to transplantation of organs from GalT-KO pigs to humans. © 2005 Nature Publishing Group
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