545 research outputs found
Hawking Radiation for Non-minimally Coupled Matter from Generalized 2D Black Hole Models
It is well known that spherically symmetric reduction of General Relativity
(SSG) leads to non-minimally coupled scalar matter. We generalize (and correct)
recent results to Hawking radiation for a class of dilaton models which share
with the Schwarzschild black hole non-minimal coupling of scalar fields and the
basic global structure. An inherent ambiguity of such models (if they differ
from SSG) is discussed. However, for SSG we obtain the rather disquieting
result of a negative Hawking flux at infinity, if the usual recipe for such
calculations is applied.Comment: 8 page
Zirkadiane Variationen bei der Expression von ß2-Adrenoceptoren auf peripheren Lymphozythen von Gesunden und Asthmatikern
Type 0A 2D Black Hole Thermodynamics and the Deformed Matrix Model
Recently, it has been proposed that the deformed matrix model describes a
two-dimensional type 0A extremal black hole. In this paper, the thermodynamics
of 0A charged non-extremal black holes is investigated. We observe that the
free energy of the deformed matrix model to leading order in 1/q can be seen to
agree to that of the extremal black hole. We also speculate on how the deformed
matrix model is able to describe the thermodynamics of non-extremal black
holes.Comment: 12 page
Non-existence of a dilaton gravity action for the exact string black hole
We prove that no local diffeomorphism invariant two-dimensional theory of the
metric and the dilaton without higher derivatives can describe the exact string
black hole solution found a decade ago by Dijkgraaf, Verlinde and Verlinde. One
of the key points in this proof is the concept of dilaton-shift invariance. We
present and solve (classically) all dilaton-shift invariant theories of
two-dimensional dilaton gravity. Two such models, resembling the exact string
black hole and generalizing the CGHS model, are discussed explicitly.Comment: 24 pages, 3 eps-figures, revised version (more references, clarified
some of the discussion
Dimerization of visinin-like protein 1 is regulated by oxidative stress and calcium and is a pathological hallmark of amyotrophic lateral sclerosis
AbstractRedox control of proteins that form disulfide bonds upon oxidative challenge is an emerging topic in the physiological and pathophysiological regulation of protein function. We have investigated the role of the neuronal calcium sensor protein visinin-like protein 1 (VILIP-1) as a novel redox sensor in a cellular system. We have found oxidative stress to trigger dimerization of VILIP-1 within a cellular environment and identified thioredoxin reductase as responsible for facilitating the remonomerization of the dimeric protein. Dimerization is modulated by calcium and not dependent on the myristoylation of VILIP-1. Furthermore, we show by site-directed mutagenesis that dimerization is exclusively mediated by Cys187. As a functional consequence, VILIP-1 dimerization modulates the sensitivity of cells to an oxidative challenge. We have investigated whether dimerization of VILIP-1 occurs in two different animal models of amyotrophic lateral sclerosis (ALS) and detected soluble VILIP-1 dimers to be significantly enriched in the spinal cord from phenotypic disease onset onwards. Moreover, VILIP-1 is part of the ALS-specific protein aggregates. We show for the first time that the C-terminus of VILIP-1, containing Cys187, might represent a novel redox-sensitive motif and that VILIP-1 dimerization and aggregation are hallmarks of ALS. This suggests that VILIP-1 dimers play a functional role in integrating the cytosolic calcium concentration and the oxidative status of the cell. Furthermore, a loss of VILIP-1 function owing to protein aggregation in ALS could be relevant in the pathophysiology of the disease
Geometric Interpretation and Classification of Global Solutions in Generalized Dilaton Gravity
Two dimensional gravity with torsion is proved to be equivalent to special
types of generalized 2d dilaton gravity. E.g. in one version, the dilaton field
is shown to be expressible by the extra scalar curvature, constructed for an
independent Lorentz connection corresponding to a nontrivial torsion.
Elimination of that dilaton field yields an equivalent torsionless theory,
nonpolynomial in curvature. These theories, although locally equivalent exhibit
quite different global properties of the general solution. We discuss the
example of a (torsionless) dilaton theory equivalent to the --model.
Each global solution of this model is shown to split into a set of global
solutions of generalized dilaton gravity. In contrast to the theory with
torsion the equivalent dilaton one exhibits solutions which are asymptotically
flat in special ranges of the parameters. In the simplest case of ordinary
dilaton gravity we clarify the well known problem of removing the Schwarzschild
singularity by a field redefinition.Comment: 21 pages, 6 Postscript figure
Long time black hole evaporation with bounded Hawking flux
The long time behavior of an evaporating Schwarzschild black hole is studied
exploiting that it can be described by an effective theory in 2D, a particular
dilaton gravity model.
A crucial technical ingredient is Izawa's result on consistent deformations
of 2D BF theory, while the most relevant physical assumption is boundedness of
the asymptotic matter flux during the whole evaporation process.
An attractor solution, the endpoint of the evaporation process, is found. Its
metric is flat. However, the behavior of the dilaton field is nontrivial: it is
argued that during the final flicker a first order phase transition occurs from
a linear to a constant dilaton vacuum, thereby emitting a shock wave with a
total energy of a fraction of the Planck mass. Another fraction of the Planck
mass may reside in a cold remnant. [Note: More detailed abstract in the paper]Comment: 34 pages, 6 figures, v2: included new references and 2 new footnotes;
v3: mayor revisions (extended intro, included pedagogical example, rearranged
presentation, extended discussion on information paradox, updated
references); v4: updated refs. (+ new ones), added comments, mostly on
dilaton evaporation, rewrote abstract (short for arXiv, long for journal),
moved pedagogic sec. to ap
An action for the exact string black hole
A local action is constructed describing the exact string black hole
discovered by Dijkgraaf, Verlinde and Verlinde in 1992. It turns out to be a
special 2D Maxwell-dilaton gravity theory, linear in curvature and field
strength. Two constants of motion exist: mass M>1, determined by the level k,
and U(1)-charge Q>0, determined by the value of the dilaton at the origin. ADM
mass, Hawking temperature T_H \propto \sqrt{1-1/M} and Bekenstein-Hawking
entropy are derived and studied in detail. Winding/momentum mode duality
implies the existence of a similar action, arising from a branch ambiguity,
which describes the exact string naked singularity. In the strong coupling
limit the solution dual to AdS_2 is found to be the 5D Schwarzschild black
hole. Some applications to black hole thermodynamics and 2D string theory are
discussed and generalizations - supersymmetric extension, coupling to matter
and critical collapse, quantization - are pointed out.Comment: 41 pages, 2 eps figures, dedicated to Wolfgang Kummer on occasion of
his Emeritierung; v2: added ref; v3: extended discussion in sections 3.2, 3.3
and at the end of 5.3 by adding 2 pages of clarifying text; updated refs;
corrected typo
Novel insights into host-fungal pathogen interactions derived from live-cell imaging
Acknowledgments The authors acknowledge funding from the Wellcome Trust (080088, 086827, 075470 and 099215) including a Wellcome Trust Strategic Award for Medical Mycology and Fungal Immunology 097377 and FP7-2007–2013 grant agreement HEALTH-F2-2010-260338–ALLFUN to NARG.Peer reviewedPublisher PD
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