2,174 research outputs found
Holographic Domains of Anti-de Sitter Space
An AdS_4 brane embedded in AdS_5 exhibits the novel feature that a
four-dimensional graviton is localized near the brane, but the majority of the
infinite bulk away from the brane where the warp factor diverges does not see
four-dimensional gravity. A naive application of the holographic principle from
the point of view of the four-dimensional observer would lead to a paradox; a
global holographic mapping would require infinite entropy density. In this
paper, we show that this paradox is resolved by the proper covariant
formulation of the holographic principle. This is the first explicit example of
a time-independent metric for which the spacelike formulation of the
holographic principle is manifestly inadequate. Further confirmation of the
correctness of this approach is that light-rays leaving the brane intersect at
the location where we expect four-dimensional gravity to no longer dominate. We
also present a simple method of locating CFT excitations dual to a particle in
the bulk. We find that the holographic image on the brane moves off to infinity
precisely when the particle exits the brane's holographic domain. Our analysis
yields an improved understanding of the physics of the AdS_4/AdS_5 model.Comment: 29 pages, 6 figure
Development of lightweight, fire-retardant, low-smoke, high-strength, thermally stable aircraft floor paneling
Extensive fire resistance and mechanical property tests were conducted on sandwich configurations composed of resin-fiberglass laminates bonded with adhesive to Nomex honeycomb and foam core. The test results were used to select a combination of materials that would improve the fire safety of the airplane without sacrificing mechanical performance of the aircraft floor panels. A test panel is being service evaluated in a commercial aircraft
Perioperative and anesthetic deaths: toxicological and medico legal aspects
Background: Anesthesia has become safer during decades, though there is still a preventable mortality; the complexity of medical and surgical interventions, increasingly older and sicker patients, has created a host of new hazards in anesthesiology. In this paper, some of these perioperative (PO) fatal adverse events are investigated in terms of health responsibility. Selective literature research in several data bases, concerning perioperative and anesthetic deaths and medical responsibility, was performed. Main text: A generally accepted definition of the anesthesia and perioperatory-related death still remains one of the major concerns in forensic pathology, and the terms “operative deaths” and “anesthetic deaths” are usually applied inaccurately within the medico-legal literature. Such events involve comprehensively PO fatalities and allow for subtle separation of natural and unnatural death, at least from the prospective of forensic pathology. Iatrogenic deaths in this field can be separated into some major categories, as attributable to previous patient’s unfavorable conditions or depending from surgical procedure per se (such as PO cardiac and cerebrovascular events). In this review, the authors carried out syntheses of specific research areas regarding epidemiology, complications of general and spinal anesthetic, failure in airway management and patient’s circulatory homeostasis, and adverse drugs reactions; analysis considering the challenge of anesthetic-related mortality, epidemiology and classifications, by indicating causal chain of death, in respect of both contributing and associated anesthetic and surgery facts. Conclusions: Perioperative quality control programs and its relevance for medico-legal evaluation are emphasized as, although mortality rates have decreased worldwide over the last decades, however, preventable drug-related deaths still happen. Such fatal events have to be considered within the field of forensic pathology experts, with regard of malpractice claims, to implement a strategy for preventing potentially fatal complications
Curved BPS domain walls and RG flow in five dimensions
We determine, in the context of five-dimensional gauged
supergravity with vector and hypermultiplets, the conditions under which curved
(non Ricci flat) supersymmetric domain wall solutions may exist. These curved
BPS domain wall solutions may, in general, be supported by non-constant vector
and hyper scalar fields. We establish our results by a careful analysis of the
BPS equations as well as of the associated integrability conditions and the
equations of motion. We construct an example of a curved BPS solution in a
gauged supergravity model with one hypermultiplet. We also discuss the dual
description of curved BPS domain walls in terms of RG flows.Comment: 18 pages, LaTeX, 5 figures; added reference
A Closer Look at Two Branes in an Bulk
We investigate a scenario with two branes in an bulk. In this
scenario there are two gravitons and we investigate the role played by each of
them for different positions of the second brane. We show that both gravitons
play a significant role only when the turn-around point in the warp factor is
approximately equidistant from both branes. We find that the ultralight mode
becomes heavy as the second brane approaches the turn-around point, and the
physics begins to resemble that of the RS model. Thus we demonstrate the
crucial role played by the turn-around in the warp factor in enabling the
presence of both gravitons.Comment: 21 pages, late
Development of lightweight, fire-retardant, low smoke, high strength, thermally stable aircraft floor paneling
Boeing's participation in a NASA funded program (FIREMEN) to develop materials for use as floor panels possessing flammability, smoke and toxicity characteristics superior to current materials is outlined. The objectives of the program are to develop an aircraft floor paneling suitable for high traffic areas, e.g., aisle or galley and to install and certify the panel in a commercial aircraft for service evaluation
On the sign of the dilaton in the soft wall models
We elaborate on the existence of a spurious massless scalar mode in the
vector channel of soft-wall models with incorrectly chosen sign of the
exponential profile defining the wall. We re-iterate the point made in our
earlier paper and demonstrate that the presence of the mode is robust,
depending only on the infra-red asymptotics of the wall. We also re-emphasize
that desired confinement properties can be realized with the correct sign
choice.Comment: 10 page
Scalar potential from de Sitter brane in 5D and effective cosmological constant
We derive the scalar potential in zero mode effective action arising from a
de Sitter brane embedded in five dimensions with bulk cosmological constant
. The scalar potential for a scalar field canonically normalized is
given by the sum of exponential potentials. In the case of and
, we point out that the scalar potential has an unstable local
maximum at the origin and exponentially vanishes for large positive scalar
field. In the case of , the scalar potential has an unstable local
maximum at the origin and a stable local minimum, it is shown that the positive
cosmological constant in brane is reduced by negative potential energy of
scalar at minimum.Comment: 14 pages, 5 figures, add the section of cosmological implication
AdS/CFT with Flavour in Electric and Magnetic Kalb-Ramond Fields
We investigate gauge/gravity duals with flavour for which pure-gauge
Kalb-Ramond B fields are turned on in the background, into which a D7 brane
probe is embedded. First we consider the case of a magnetic field in two of the
spatial boundary directions. We show that at finite temperature, i.e. in the
AdS-Schwarzschild background, the B field has a stabilizing effect on the
mesons and chiral symmetry breaking occurs for a sufficiently large value of
the B field. Then we turn to the electric case of a B field in the temporal
direction and one spatial boundary direction. In this case, there is a singular
region in which it is necessary to turn on a gauge field on the brane in order
to ensure reality of the brane action. We find that the brane embeddings are
attracted towards this region. Far away from this region, in the weak field
case at zero temperature, we investigate the meson spectrum and find a mass
shift similar to the Stark effect.Comment: 34 pages, 18 figures, v2: added references and comments on mode
decoupling, on thermodynamics and holographic renormalisation, JHEP style,
v3: Final published versio
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