600 research outputs found
QCD Supersymmetry and Low Energy Gravity
In this contributed paper we discuss some aspects of scenarios with Extra
Dimensions at the LHC and in cosmic rays.Comment: Contributed paper to the Conference "Quark confinement ant the Hadron
Spectrum VI 2004". Latex, 3 page
An electron jet pump: The Venturi effect of a Fermi liquid
A three-terminal device based on a two-dimensional electron system is
investigated in the regime of non-equilibrium transport. Excited electrons
scatter with the cold Fermi sea and transfer energy and momentum to other
electrons. A geometry analogous to a water jet pump is used to create a jet
pump for electrons. Because of its phenomenological similarity we name the
observed behavior "electronic Venturi effect".Comment: Journal of Applied Physics Special Topic: Plenary and Invited Papers
from the 30th International Conference on the Physics of Semiconductors,
Seoul, Korea, 2010; http://link.aip.org/link/?JAP/109/10241
Gravitating defects of codimension-two
Thin gravitating defects with conical singularities in higher codimensions
and with generalized Israel matching conditions are known to be inconsistent
for generic energy-momentum. A way to remove this inconsistency is proposed and
is realized for an axially symmetric gravitating codimension-two defect in six
dimensional Einstein gravity. By varying with respect to the brane embedding
fields, alternative matching conditions are derived, which are generalizations
of the Nambu-Goto equations of motion of the defect, consistent with bulk
gravity. For a maximally symmetric defect the standard picture is recovered.
The four-dimensional perfect fluid cosmology coincides with conventional FRW in
the case of radiation, but for dust it has rho^{4/3} instead of rho. A
four-dimensional black hole solution is presented having the Schwarzschild form
with a short-distance correction r^{-2}.Comment: Minor changes, to appear in Classical and Quantum Gravit
Some properties of the Alday-Maldacena minimum
The Alday-Maldacena solution, relevant to the n=4 gluon amplitude in N=4 SYM
at strong coupling, was recently identified as a minimum of the regularized
action in the moduli space of solutions of the AdS_5 sigma-model equations of
motion. Analogous solutions of the Nambu-Goto equations for the n=4 case are
presented and shown to form (modulo the reparametrization group) an equally
large but different moduli space, with the Alday-Maldacena solution at the
intersection of the sigma-model and Nambu-Goto moduli spaces. We comment upon
the possible form of the regularized action for n=5. A function of moduli
parameters z_a is written, whose minimum reproduces the BDDK one-loop
five-gluon amplitude. This function may thus be considered as some kind of
Legendre transform of the BDDK formula and has its own value independently of
the Alday-Maldacena approach.Comment: 10 page
Towards a covariant model for cosmic self-acceleration
An explicitly covariant formulation is presented of a modified DGP scenario
proposed recently [1], to avoid the instability of the self-accelerating
branch. It is based on the introduction of a bulk scalar field with appropriate
non-minimal coupling to the bulk Einstein-Hilbert term. The method is general
and may be applied to other models as well.Comment: 10 pages, no figures; v2: version published in JHE
Induced Gravity on RS Branes
It is shown that a localized four-dimensional Einstein term, induced by
quantum corrections, modifies significantly the law of gravity in a
Randall-Sundrum brane world. In particular, the short-distance behavior of
gravity changes from five- to four-dimensional, while, depending on the values
of parameters, there can be an intermediate range where gravity behaves as in
five dimensions. The spectrum of graviton fluctuations around the brane, their
relative importance for the gravitational force, and the relevance of their
emission in the bulk for the brane cosmology are analysed. Finally, constraints
on parameters are derived from energy loss in astrophysical and particle
physics processes.Comment: 20 pages, 1 figure, JHEP.cl
Tat-SF1 Is Not Required for Tat Transactivation but Does Regulate the Relative Levels of Unspliced and Spliced HIV-1 RNAs
.To directly address the involvement of Tat-SF1 in HIV-1 gene expression, we depleted Tat-SF1 in HeLa cells by conventional expression of shRNAs and in T- Rex -293 cells containing tetracycline-inducible shRNAs targeting Tat-SF1. We achieved efficient depletion of Tat-SF1 and demonstrated that this did not affect cell viability. HIV-1 infectivity decreased in Tat-SF1-depleted cells, but only when multiple rounds of infection occurred. Neither Tat-dependent nor basal transcription from the HIV-1 LTR was affected by Tat-SF1 depletion, suggesting that the decrease in infectivity was due to a deficiency at a later step in the viral lifecycle. Finally, Tat-SF1 depletion resulted in an increase in the ratio of unspliced to spliced viral transcripts.Tat-SF1 is not required for regulating HIV-1 transcription, but is required for maintaining the ratios of different classes of HIV-1 transcripts. These new findings highlight a novel, post-transcriptional role for Tat-SF1 in the HIV-1 life cycle
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