659 research outputs found
Concept for improved vacuum pressure measuring device
To measure vacuum pressures in the range of 5 times 10 to the minus 7 to 5 times 10 to the minus 16, a semiconductor resistor composed of sintered zinc oxide is used. Through the effect of surface absorbed gases on the resistance of the semiconductor material, very low pressures are measured
Anatomy of a Bounce
Holographic considerations are used in the scrutiny of a special class of
brane-world cosmologies. Inherently to this class, the brane typically bounces,
at a finite size, as a consequence of a charged black hole in the bulk. Whereas
a prior treatment [hep-th/0301010] emphasized a brane that is void of
standard-model matter, the analysis is now extended to include an intrinsic
(radiation-dominated) matter source. An interesting feature of this generalized
model is that a bounce is no longer guaranteed but, rather, depends on the
initial conditions. Ultimately, we demonstrate that compliance with an
appropriate holographic bound is a sufficient prerequisite for a bounce to
occur.Comment: 14 pages, Revtex; (v2) minor revisions; (v3) reference adde
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The Same, and Not the Same Men’s Narratives of Adoptive Fatherhood after Primary Infertility
Graviton n-point functions for UV-complete theories in Anti-de Sitter space
We calculate graviton n-point functions in an anti-de Sitter black brane
background for effective gravity theories whose linearized equations of motion
have at most two time derivatives. We compare the n-point functions in Einstein
gravity to those in theories whose leading correction is quadratic in the
Riemann tensor. The comparison is made for any number of gravitons and for all
physical graviton modes in a kinematic region for which the leading correction
can significantly modify the Einstein result. We find that the n-point
functions of Einstein gravity depend on at most a single angle, whereas those
of the corrected theories may depend on two angles. For the four-point
functions, Einstein gravity exhibits linear dependence on the Mandelstam
variable s versus a quadratic dependence on s for the corrected theory.Comment: 29 page
Thermal Fluctuations and Black Hole Entropy
In this paper, we consider the effect of thermal fluctuations on the entropy
of both neutral and charged black holes. We emphasize the distinction between
fixed and fluctuating charge systems; using a canonical ensemble to describe
the former and a grand canonical ensemble to study the latter. Our novel
approach is based on the philosophy that the black hole quantum spectrum is an
essential component in any such calculation. For definiteness, we employ a
uniformly spaced area spectrum, which has been advocated by Bekenstein and
others in the literature. The generic results are applied to some specific
models; in particular, various limiting cases of an (arbitrary-dimensional)
AdS-Reissner-Nordstrom black hole. We find that the leading-order quantum
correction to the entropy can consistently be expressed as the logarithm of the
classical quantity. For a small AdS curvature parameter and zero net charge, it
is shown that, independent of the dimension, the logarithmic prefactor is +1/2
when the charge is fixed but +1 when the charge is fluctuating.We also
demonstrate that, in the grand canonical framework, the fluctuations in the
charge are large, , even when .
A further implication of this framework is that an asymptotically flat,
non-extremal black hole can never achieve a state of thermal equilibrium.Comment: 25 pages, Revtex; references added and corrected, and some minor
change
Entropy Corrections for Schwarzschild and Reissner-Nordstr\"om Black Holes
Schwarzschild black hole being thermodynamically unstable, corrections to its
entropy due to small thermal fluctuations cannot be computed. However, a
thermodynamically stable Schwarzschild solution can be obtained within a cavity
of any finite radius by immersing it in an isothermal bath. For these boundary
conditions, classically there are either two black hole solutions or no
solution. In the former case, the larger mass solution has a positive specific
heat and hence is locally thermodynamically stable. We find that the entropy of
this black hole, including first order fluctuation corrections is given by:
{\cal S} = S_{BH} - \ln[\f{3}{R} (S_{BH}/4\p)^{1/2} -2]^{-1} + (1/2)
\ln(4\p), where is its Bekenstein-Hawking entropy and is the
radius of the cavity. We extend our results to four dimensional
Reissner-Nordstr\"om black holes, for which the corresponding expression is:
{\cal S} = S_{BH} - \f{1}{2} \ln [ {(S_{BH}/\p R^2) ({3S_{BH}}/{\p R^2} -
2\sqrt{{S_{BH}}/{\p R^2 -\a^2}}) \le(\sqrt{{S_{BH}}/{\p R^2}} - \a^2 \ri)}/
{\le({S_{BH}}/{\p R^2} -\a^2 \ri)^2} ]^{-1} +(1/2)\ln(4\p). Finally, we
generalise the stability analysis to Reissner-Nordstr\"om black holes in
arbitrary spacetime dimensions, and compute their leading order entropy
corrections. In contrast to previously studied examples, we find that the
entropy corrections in these cases have a different character.Comment: 6 pages, Revtex. References added, minor changes. Version to appear
in Class. Quant. Gra
Of Bounces, Branes and Bounds
Some recent studies have considered a Randall-Sundrum-like brane world
evolving in the background of an anti-de Sitter Reissner-Nordstrom black hole.
For this scenario, it has been shown that, when the bulk charge is
non-vanishing, a singularity-free ``bounce'' universe will always be obtained.
However, for the physically relevant case of a de Sitter brane world, we have
recently argued that, from a holographic (c-theorem) perspective, such brane
worlds may not be physically viable. In the current paper, we reconsider the
validity of such models by appealing to the so-called ``causal entropy bound''.
In this framework, a paradoxical outcome is obtained: these brane worlds are
indeed holographically viable, provided that the bulk charge is not too small.
We go on to argue that this new finding is likely the more reliable one.Comment: 15 pages, Revtex; references added and very minor change
Bouncing cosmological solutions and their stability
In the present paper we consider the bouncing braneworld scenario, in which
the bulk is given by a five-dimensional charged AdS black hole spacetime with
matter field confined in a brane. Then, we study the stability of
solutions with respect to homogeneous and isotropic perturbations.
Specifically, the AdS black hole with zero ADM mass and charge, and open
horizon is an attractor, while the charged AdS black hole with zero ADM mass
and flat horizon, is a repeller.Comment: 9 pages, 1 figur
A Study of RO5217790 (HPV Targeted Immunotherapy) in Patients With High Grade Cervical Intraepithelial Neoplasia Associated With High Risk HPV Infection
Comparative Medicine - OneHealth and Comparative Medicine Poster SessionThis is a randomized, double blind, placebo controlled, parallel group multicenter study in women with biopsy confirmed Grade 2 or Grade 3 cervical intraepithelial neoplasia (CIN). Two hundred patients will be enrolled and randomized in a 2: 1 ratio of RO5217790: placebo. They will be stratified on the basis of their HPV genotyping with stratum 1 consisting of those women with HPV 16 single infection and stratum 2 consisting of those with single or multiple infections with other high risk genotypes. Three injections of RO5217790 (5 x 107pfu) will be administered subcutaneously, each one week apart. Interim colposcopy, cytology and HPV assessments will be performed at Month 3. All patients will undergo conization at Month 6. The primary endpoint is histologic response at Month 6 in HPV 16 single infected patients, as assessed by central pathology review. The secondary endpoints include histologic response in all CIN2/3 patients enrolled regardless of genotype, viral clearance, safety, and immune response (cellular and humoral). After the Month 6 conization, the study will be unblinded and patients will undergo follow-up for an additional 2 years for efficacy and safety. This includes visits at Months 12, 18, 24 and 30 to assess histologic relapse/recurrence and viral re-infection as well as reporting of any serious adverse events. An interim analysis will be conducted when a minimum of 80 patients (at least 20 of whom have single infection with HPV 16 and 20 of whom have infection with HPV 16 plus HPV 16 related genotypes) have undergone conization. NCT0102234
Porous sandwich ceramic of layered silicon nitride-zirconia composite with various multilayered graphene content
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