2,060 research outputs found
A Viral Ubiquitin Ligase Has Substrate Preferential SUMO Targeted Ubiquitin Ligase Activity that Counteracts Intrinsic Antiviral Defence
Intrinsic antiviral resistance represents the first line of intracellular defence against virus infection. During herpes simplex virus type-1 (HSV-1) infection this response can lead to the repression of viral gene expression but is counteracted by the viral ubiquitin ligase ICP0. Here we address the mechanisms by which ICP0 overcomes this antiviral response. We report that ICP0 induces the widespread proteasome-dependent degradation of SUMO-conjugated proteins during infection and has properties related to those of cellular SUMO-targeted ubiquitin ligases (STUbLs). Mutation of putative SUMO interaction motifs within ICP0 not only affects its ability to degrade SUMO conjugates, but also its capacity to stimulate HSV-1 lytic infection and reactivation from quiescence. We demonstrate that in the absence of this viral countermeasure the SUMO conjugation pathway plays an important role in mediating intrinsic antiviral resistance and the repression of HSV-1 infection. Using PML as a model substrate, we found that whilst ICP0 preferentially targets SUMO-modified isoforms of PML for degradation, it also induces the degradation of PML isoform I in a SUMO modification-independent manner. PML was degraded by ICP0 more rapidly than the bulk of SUMO-modified proteins in general, implying that the identity of a SUMO-modified protein, as well as the presence of SUMO modification, is involved in ICP0 targeting. We conclude that ICP0 has dual targeting mechanisms involving both SUMO- and substrate-dependent targeting specificities in order to counteract intrinsic antiviral resistance to HSV-1 infection
Magnetic Fields from Phase Transitions
The generation of primordial magnetic fields from cosmological phase
transitions is discussed, paying particular attention to the electroweak
transition and to the various definitions of the `average' field that have been
put forward. It is emphasised that only the volume average has dynamical
significance as a seed for galactic dynamos. On rather general grounds of
causality and energy conservation, it is shown that, in the absence of MHD
effects that transfer power in the magnetic field from small to large scales,
processes occurring at the electroweak transition cannot generate fields
stronger than Gauss on a scale of 0.5 Mpc. However, it is
implausible that this upper bound could ever be reached, as it would require
all the energy in the Universe to be turned into a magnetic field coherent at
the horizon scale. Non-linear MHD effects seem therefore to be necessary if the
electroweak transition is to create a primordial seed field.Comment: 6pp RevTeX. Correct finished version supplie
Searching singlet extensions of the supersymmetric standard model in orbifold compactification of heterotic string
We search for supersymmetric standard model realizations with extra singlets
and extra using the heterotic string compactification on the orbifold with two Wilson lines. We analyze the vacuum restabilization
mechanism for three representative Pati-Salam string models obtained in the
literature and present detailed results for the effective superpotential
compatible with the string selection rules. An automated selection of
semi-realistic vacua along flat directions in the non-Abelian singlet modes
field space is performed by requiring the presence of massless pairs of
electroweak Higgs bosons having trilinear superpotential couplings with
massless singlet modes and the decoupling of color triplet exotic modes needed
to suppress and number violating processes.Comment: revtex4 format, 21 pages, 7 tables, shortened version added
reference
Bostonia: The Boston University Alumni Magazine. Volume 12
Founded in 1900, Bostonia magazine is Boston University’s main alumni publication
Contribution to understanding the mathematical structure of quantum mechanics
Probabilistic description of results of measurements and its consequences for
understanding quantum mechanics are discussed. It is shown that the basic
mathematical structure of quantum mechanics like the probability amplitudes,
Born rule, commutation and uncertainty relations, probability density current,
momentum operator, rules for including the scalar and vector potentials and
antiparticles can be obtained from the probabilistic description of results of
measurement of the space coordinates and time. Equations of motion of quantum
mechanics, the Klein-Gordon equation, Schrodinger equation and Dirac equation
are obtained from the requirement of the relativistic invariance of the
space-time Fisher information. The limit case of the delta-like probability
densities leads to the Hamilton-Jacobi equation of classical mechanics. Many
particle systems and the postulates of quantum mechanics are also discussed.Comment: 21 page
A Measurement of the Cosmic Microwave Background Gravitational Lensing Potential from 100 Square Degrees of SPTpol Data
We present a measurement of the cosmic microwave background (CMB)
gravitational lensing potential using data from the first two seasons of
observations with SPTpol, the polarization-sensitive receiver currently
installed on the South Pole Telescope (SPT). The observations used in this work
cover 100 deg of sky with arcminute resolution at 150 GHz. Using a
quadratic estimator, we make maps of the CMB lensing potential from
combinations of CMB temperature and polarization maps. We combine these lensing
potential maps to form a minimum-variance (MV) map. The lensing potential is
measured with a signal-to-noise ratio of greater than one for angular
multipoles between . This is the highest signal-to-noise mass map
made from the CMB to date and will be powerful in cross-correlation with other
tracers of large-scale structure. We calculate the power spectrum of the
lensing potential for each estimator, and we report the value of the MV power
spectrum between as our primary result. We constrain the ratio
of the spectrum to a fiducial CDM model to be . Restricting ourselves to
polarized data only, we find . This measurement rejects the hypothesis of no lensing at
using polarization data alone, and at using both
temperature and polarization data.Comment: 16 pages, 8 figure
Where the Sidewalk Ends: Jets and Missing Energy Search Strategies for the 7 TeV LHC
This work explores the potential reach of the 7 TeV LHC to new colored states
in the context of simplified models and addresses the issue of which search
regions are necessary to cover an extensive set of event topologies and
kinematic regimes. This article demonstrates that if searches are designed to
focus on specific regions of phase space, then new physics may be missed if it
lies in unexpected corners. Simple multiregion search strategies can be
designed to cover all of kinematic possibilities. A set of benchmark models are
created that cover the qualitatively different signatures and a benchmark
multiregion search strategy is presented that covers these models.Comment: 30 pages, 8 Figures, 3 Tables. Version accepted at JHEP. Minor
changes. Added figur
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