1,513 research outputs found
AdS flowing black funnels: Stationary AdS black holes with non-Killing horizons and heat transport in the dual CFT
We construct stationary non-equilibrium black funnels locally asymptotic to
global AdS4 in vacuum Einstein-Hilbert gravity with negative cosmological
constant. These are non-compactly-generated black holes in which a single
connected bulk horizon extends to meet the conformal boundary. Thus the induced
(conformal) boundary metric has smooth horizons as well. In our examples, the
boundary spacetime contains a pair of black holes connected through the bulk by
a tubular bulk horizon. Taking one boundary black hole to be hotter than the
other () prohibits equilibrium. The result is a so-called
flowing funnel, a stationary bulk black hole with a non-Killing horizon that
may be said to transport heat toward the cooler boundary black hole. While
generators of the bulk future horizon evolve toward zero expansion in the far
future, they begin at finite affine parameter with infinite expansion on a
singular past horizon characterized by power-law divergences with universal
exponents. We explore both the horizon generators and the boundary stress
tensor in detail. While most of our results are numerical, a semi-analytic
fluid/gravity description can be obtained by passing to a one-parameter
generalization of the above boundary conditions. The new parameter detunes the
temperatures and of the bulk and boundary black
holes, and we may then take \alpha =
and \Delta T small to control the accuracy of the fluid-gravity approximation.
In the small \alpha, \Delta T regime we find excellent agreement with our
numerical solutions. For our cases the agreement also remains quite good even
for . In terms of a dual CFT, our \alpha = 1 solutions
describe heat transport via a large N version of Hawking radiation through a
deconfined plasma that couples efficiently to both boundary black holes
Rotating black droplet
We construct the gravitational dual, in the Unruh state, of the "jammed"
phase of a CFT at strong coupling and infinite N on a fixed five-dimensional
rotating Myers-Perry black hole with equal angular momenta. When the angular
momenta are all zero, the solution corresponds to the five-dimensional
generalization of the solution first studied by Figueras, Lucietti, and
Wiseman. In the extremal limit, when the angular momenta of the Myers-Perry
black hole are maximum, the Unruh, Boulware and Hartle-Hawking states
degenerate. We give a detailed analysis of the corresponding holographic stress
energy tensor for all values of the angular momenta, finding it to be regular
at the horizon in all cases. We compare our results with existent literature on
thermal states of free field theories on black hole backgrounds
The role of electron-electron scattering in spin transport
We investigate spin transport in quasi 2DEG formed by III-V semiconductor
heterojunctions using the Monte Carlo method. The results obtained with and
without electron-electron scattering are compared and appreciable difference
between the two is found. The electron-electron scattering leads to suppression
of Dyakonov-Perel mechanism (DP) and enhancement of Elliott-Yafet mechanism
(EY). Finally, spin transport in InSb and GaAs heterostructures is investigated
considering both DP and EY mechanisms. While DP mechanism dominates spin
decoherence in GaAs, EY mechanism is found to dominate in high mobility InSb.
Our simulations predict a lower spin relaxation/decoherence rate in wide gap
semiconductors which is desirable for spin transport.Comment: to appear in Journal of Applied Physic
Branching on multi-aggregated variables
open5siopenGamrath, Gerald; Melchiori, Anna; Berthold, Timo; Gleixner, Ambros M.; Salvagnin, DomenicoGamrath, Gerald; Melchiori, Anna; Berthold, Timo; Gleixner, Ambros M.; Salvagnin, Domenic
The graceful exit from the anomaly-induced inflation: Supersymmetry as a key
The stable version of the anomaly-induced inflation does not need a fine
tuning and leads to sufficient expansion of the Universe. The non-stable
version (Starobinsky model) provides the graceful exit to the FRW phase. We
indicate the possibility of the inflation which is stable at the beginning and
unstable at the end. The effect is due to the soft supersymmetry breaking and
the decoupling of the massive sparticles at low energy.Comment: 10 pages, 2 figures using axodraw. Modified version. Discussion
concerning the gravitational scale modified, the effect of massive particles
in the last stage of inflation taken into accoun
Anchoring of proteins to lactic acid bacteria
The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB. The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall. In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display. The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted.
Complete phenomenological gravitational waveforms from spinning coalescing binaries
The quest for gravitational waves from coalescing binaries is customarily
performed by the LIGO-Virgo collaboration via matched filtering, which requires
a detailed knowledge of the signal. Complete analytical coalescence waveforms
are currently available only for the non-precessing binary systems. In this
paper we introduce complete phenomenological waveforms for the dominant
quadrupolar mode of generically spinning systems. These waveforms are
constructed by bridging the gap between the analytically known inspiral phase,
described by spin Taylor (T4) approximants in the restricted waveform
approximation, and the ring-down phase through a phenomenological intermediate
phase, calibrated by comparison with specific, numerically generated waveforms,
describing equal mass systems with dimension-less spin magnitudes equal to 0.6.
The overlap integral between numerical and phenomenological waveforms ranges
between 0.95 and 0.99.Comment: Proceeding for the GWDAW-14 conference. Added reference in v
Characterisation of the secondary-neutron production in particle therapy treatments with the MONDO tracking detector
Particle Therapy (PT) is a non-invasive technique that exploits charged light ions for the irradiation of tumours that cannot be effectively treated with surgery or conventional radiotherapy. While the largest dose fraction is released to the tumour volume by the primary beam, a non-negligible amount of additional dose is due to the beam fragmentation that occurs along the path towards the target volume. In particular, the produced neutrons are particularly dangerous as they can release their energy far away from the treated area, increasing the risk of developing a radiogenic secondary malignant neoplasm after undergoing a treatment. A precise measurement of the neutron flux, energy spectrum and angular distributions is eagerly needed in order to improve the treatment planning system software, so as to predict the normal tissue toxicity in the target region and the risk of late complications in the whole body. The MONDO (MOnitor for Neutron Dose in hadrOntherapy) project is dedicated to the characterisation of the secondary ultra-fast neutrons ([20-400] MeV energy range) produced in PT. The neutron tracking system exploits the reconstruction of the recoil protons produced in two consecutive (n, p) elastic scattering interactions to measure simultaneously the neutron incoming direction and energy. The tracker active media is a matrix of thin squared scintillating fibers arranged in orthogonally oriented layers that are read out by a sensor (SBAM) based on SPAD (Single-Photon Avalanche Diode) detectors developed in collaboration with the Fondazione Bruno Kessler (FBK)
Calculation of the electron mobility in III-V inversion layers with high-kappa dielectrics
We calculate the electron mobility for a metal-oxide-semiconductor system with a metallic gate, high-kappa dielectric layer, and III-V substrate, including scattering with longitudinal-optical (LO) polar-phonons of the III-V substrate and with the interfacial excitations resulting from the coupling of insulator and substrate optical modes among themselves and with substrate plasmons. In treating scattering with the substrate LO-modes, multisubband dynamic screening is included and compared to the dielectric screening in the static limit and with the commonly used screening model obtained by defining an effective screening wave vector. The electron mobility components limited by substrate LO phonons and interfacial modes are calculated for In0.53Ga0.47As and GaAs substrates with SiO2 and HfO2 gate dielectrics. The mobility components limited by the LO-modes and interfacial phonons are also investigated as a function of temperature. Scattering with surface roughness, fixed interface charge, and nonpolar-phonons is also included to judge the relative impact of each scattering mechanism in the total mobility for In0.53Ga0.47As with HfO2 gate dielectric. We show that InGaAs is affected by interfacial-phonon scattering to an extent larger than Si, lowering the expected performance, but probably not enough to question the technological relevance of InGaAs. (C) 2010 American Institute of Physics. [doi:10.1063/1.3500553
In-room test results at CNAO of an innovative PT treatments online monitor (Dose Profiler)
The use of C, He and O ions as projectiles in Particle Therapy (PT) treatments is getting more and more widespread as a consequence of their enhanced relative biological effectiveness and oxygen enhancement ratio, when compared to the protons one. The advantages related to the incoming radiation improved efficacy are requiring an accurate online monitor of the dose release spatial distribution. Such monitor is necessary to prevent unwanted damage to the tissues surrounding the tumour that can arise, for example, due to morphological changes occurred in the patient during the treatment with respect to the initial CT scan. PT treatments with ions can be monitored by detecting the secondary radiation produced by the primary beam interactions with the patient body along the path towards the target volume. Charged fragments produced in the nuclear process of projectile fragmentation can be emitted at large angles with respect to the incoming beam direction and can be detected with high efficiency in a nearly background-free environment. The Dose Profiler (DP) detector, developed within the INSIDE project, is a scintillating fibre tracker that allows an online reconstruction and backtracking of such secondary charged fragments. The construction and preliminary in-room tests performed on the DP, carried out using the 12C ions beam of the CNAO treatment centre using an anthropomorphic phantom as a target, will be reviewed in this contribution. The impact of the secondary fragments interactions with the patient body will be discussed in view of a clinical application. Furthermore, the results implications for a pre-clinical trial on CNAO patients, foreseen in 2019, will be discussed
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