775 research outputs found
Rapid Thermalization in Field Theory from Gravitational Collapse
Motivated by the duality with thermalization in field theory, we study
gravitational collapse of a minimally coupled massless scalar field in Einstein
gravity with a negative cosmological constant. We investigate the system
numerically and establish that for small values of the initial amplitude of the
scalar field there is no black hole formation, rather, the scalar field
performs an oscillatory motion typical of geodesics in AdS. For large enough
values of the amplitude of the scalar field we find black hole formation which
we detect numerically as the emergence of an apparent horizon. Using the time
of formation as an estimate for thermalization in the field theory we conclude
that thermalization occurs very rapidly, close to the causal bound for a very
wide range of black hole masses. We further study the thermalization time in
more detail as a function of the amplitude and the width of the initial
Gaussian scalar field profile and detect a rather mild structure.Comment: 5 pages, 4 figures. v2: References added, improved most grids by a
factor of 8, main results unchanged. v3 PRD versio
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The Shrouded Borderland Between Preemption and Discrimination
In the absence of a comprehensive reform of the federal immigration system, numerous cities, counties, and local governments have passed various local laws and ordinances aimed at addressing the externalities of a growing influx of undocumented immigrants. Recently, there has been a proliferation of local ordinances that establish licensing schemes intended to prohibit a landlord from leasing his property to individuals who lack proof of citizenship or legal immigration status. Three federal circuit courts have addressed potential preemption issues that arise from such ordinances. Due to the lack of clarity in the U.S. Supreme Court’s preemption jurisprudence within the context of immigration law, the three circuits have split over the validity of these local efforts to deny undocumented immigrants the right to basic housing. While one of the federal circuit courts examined in this Note has found such ordinances to not be preempted by federal immigration law, the other two courts to consider the issue have reached the opposite conclusion. In so doing, each federal circuit court decision has relied on the ambiguities of the doctrine of preemption to advance or hinder local laws that discriminate against undocumented foreigners. In light of this background, this Note analyzes the discriminatory implications of such local immigration laws. More importantly, this Note proposes an analytical framework that will offer a unified, non-discriminatory federal answer concerning the authority of state and local governments to adopt laws that encumber undocumented immigrants’ rights to housing
Black Holes with Varying Flux: A Numerical Approach
We present a numerical study of type IIB supergravity solutions with varying
Ramond-Ramond flux. We construct solutions that have a regular horizon and
contain nontrivial five- and three-form fluxes. These solutions are
holographically dual to the deconfined phase of confining field theories at
finite temperature. As a calibration of the numerical method we first
numerically reproduce various analytically known solutions including singular
and regular nonextremal D3 branes, the Klebanov-Tseytlin solution and its
singular nonextremal generalization. The horizon of the solutions we construct
is of the precise form of nonextremal D3 branes. In the asymptotic region far
away from the horizon we observe a logarithmic behavior similar to that of the
Klebanov-Tseytlin solution.Comment: 40 pages, 15 figure
Black Holes in Cascading Theories: Confinement/Deconfinement Transition and other Thermal Properties
We present numerical evidence for a transition between the Klebanov-Strassler
background and a solution describing a black hole in the class of cascading
solutions in the chirally restored phase. We also present a number of
properties of this solution, including the running of the coupling constant,
the viscosity to entropy ratio and the drag force on a quark moving in this
background.Comment: 34 pages, 7 figures. Version to be published by JHE
Low-Temperature Glassy Response of Ultrathin Manganite Films to Electric and Magnetic Fields
The glassy response of thin films of La0.8Ca0.2MnO3 to external magnetic and
gated electrostatic fields in a field-effect geometry has been studied at low
temperatures. A hierarchical response with irreversible memory effects,
non-ergodic time evolution, aging and annealing behavior of the resistance
suggest that the dynamics are governed by strain relaxation for both electronic
and magnetic perturbations. Cross-coupling of charge, spin, and strain have
been exploited to tune the coercivity of an ultrathin manganite film by
electrostatic gating.Comment: 4 pages, 5 figure
Holographic Entanglement Entropy at Finite Temperature
Using a holographic proposal for the entanglement entropy we study its
behavior in various supergravity backgrounds. We are particularly interested in
the possibility of using the entanglement entropy as way to detect transitions
induced by the presence horizons. We consider several geometries with horizons:
the black hole in , nonextremal Dp-branes, dyonic black holes
asymptotically to and also Schwarzschild black holes in global
coordinates. Generically, we find that the entanglement entropy does not
exhibit a transition, that is, one of the two possible configurations always
dominates.Comment: v3: 31 pp, ten figures, modified to match version accepted by IJMP
Adjuvants : an essential component of neisseria vaccines
Adjuvants may be classified into delivery systems and immune potentiator or modulator molecules based on their mechanism of action. Neisseria vaccines containing traditional adjuvants such as aluminium salts have existed for long time, but meningitis caused by Neisseria meningitidis serogroups, particularly serogroup B, continues to be a global health problem. Novel strategies have applied in silico and recombinant technologies to develop "universal" antigens (e.g. proteins, peptides and plasmid DNA) for vaccines, but these antigens have been shown to be poorly immunogenic even when alum adjuvanted, implying a need for better vaccine design. In this work we review the use of natural, detoxified, or synthetic molecules in combination with antigens to activate the innate immune system and to modulate the adaptive immune responses. In the main, antigenic and imune potentiator signals are delivered using nano-, micro-particles, alum, or emulsions. The importance of interaction between adjuvants and antigens to activate and target dendritic cells, the bridge between the innate and adaptive immune systems, will be discussed. In addition, nasal vaccine strategies based on the development of mucosal adjuvants and Neisseria derivatives to eliminate the pathogen at the site of infection provide promising adjuvants effective not only against respiratory pathogens, but also against pathogens responsible for enteric and sexually transmitted diseases
A Kolmogorov-Zakharov Spectrum in Gravitational Collapse
We study black hole formation during the gravitational collapse of a massless
scalar field in asymptotically spacetimes for . We conclude that
spherically symmetric gravitational collapse in asymptotically spaces is
turbulent and characterized by a Kolmogorov-Zakharov spectrum. Namely, we find
that after an initial period of weakly nonlinear evolution, there is a regime
where the power spectrum of the Ricci scalar evolves as with the
frequency, , and .Comment: 5 pages, 4 figures. v2: Typos, other initial profile considered for
universality, error analysis, close to PRL versio
Glueball Regge trajectories from gauge/string duality and the Pomeron
The spectrum of light baryons and mesons has been reproduced recently by
Brodsky and Teramond from a holographic dual to QCD inspired in the AdS/CFT
correspondence. They associate fluctuations about the AdS geometry with four
dimensional angular momenta of the dual QCD states. We use a similar approach
to estimate masses of glueball states with different spins and their
excitations. We consider Dirichlet and Neumann boundary conditions and find
approximate linear Regge trajectories for these glueballs. In particular the
Neumann case is consistent with the Pomeron trajectory.Comment: In this revised version we made some additional remarks on the text.
We also included 2 more references. The glueball spectrum and Regge
trajectories are unchanged. 10 pages, 2 eps figure
Analytic Non-integrability in String Theory
Using analytic techniques developed for Hamiltonian dynamical systems we show
that a certain classical string configurations in AdS_5 x X_5 with X_5 in a
large class of Einstein spaces, is non-integrable. This answers the question of
integrability of string on such backgrounds in the negative. We consider a
string localized in the center of AdS_5 that winds around two circles in the
manifold X_5.Comment: 14 page
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