393 research outputs found
Multiflavor Correlation Functions in non-Abelian Gauge Theories at Finite Density in two dimensions
We compute vacuum expectation values of products of fermion bilinears for
two-dimensional Quantum Chromodynamics at finite flavored fermion densities. We
introduce the chemical potential as an external charge distribution within the
path-integral approach and carefully analyse the contribution of different
topological sectors to fermion correlators. We show the existence of chiral
condensates exhibiting an oscillatory inhomogeneous behavior as a function of a
chemical potential matrix. This result is exact and goes in the same direction
as the behavior found in QCD_4 within the large N approximation.Comment: 28 pages Latex (3 pages added and other minor changes) to appear in
Phys.Rev.
Vector Bin Packing with Multiple-Choice
We consider a variant of bin packing called multiple-choice vector bin
packing. In this problem we are given a set of items, where each item can be
selected in one of several -dimensional incarnations. We are also given
bin types, each with its own cost and -dimensional size. Our goal is to pack
the items in a set of bins of minimum overall cost. The problem is motivated by
scheduling in networks with guaranteed quality of service (QoS), but due to its
general formulation it has many other applications as well. We present an
approximation algorithm that is guaranteed to produce a solution whose cost is
about times the optimum. For the running time to be polynomial we
require and . This extends previous results for vector
bin packing, in which each item has a single incarnation and there is only one
bin type. To obtain our result we also present a PTAS for the multiple-choice
version of multidimensional knapsack, where we are given only one bin and the
goal is to pack a maximum weight set of (incarnations of) items in that bin
Confirmation of Anomalous Dynamical Arrest in attractive colloids: a molecular dynamics study
Previous theoretical, along with early simulation and experimental, studies
have indicated that particles with a short-ranged attraction exhibit a range of
new dynamical arrest phenomena. These include very pronounced reentrance in the
dynamical arrest curve, a logarithmic singularity in the density correlation
functions, and the existence of `attractive' and `repulsive' glasses. Here we
carry out extensive molecular dynamics calculations on dense systems
interacting via a square-well potential. This is one of the simplest systems
with the required properties, and may be regarded as canonical for interpreting
the phase diagram, and now also the dynamical arrest. We confirm the
theoretical predictions for re-entrance, logarithmic singularity, and give the
first direct evidence of the coexistence, independent of theory, of the two
coexisting glasses. We now regard the previous predictions of these phenomena
as having been established.Comment: 15 pages,15 figures; submitted to Phys. Rev.
Semiclassical relativistic strings in S^5 and long coherent operators in N=4 SYM theory
We consider the low energy effective action corresponding to the 1-loop,
planar, dilatation operator in the scalar sector of N=4 SU(N) SYM theory. For a
general class of non-holomorphic ``long'' operators, of bare dimension L>>1, it
is a sigma model action with 8-dimensional target space and agrees with a limit
of the phase-space string sigma model action describing generic fast-moving
strings in the S^5 part of AdS_5 x S^5. The limit of the string action is taken
in a way that allows for a systematic expansion to higher orders in the
effective coupling . This extends previous work on rigid rotating
strings in S^5 (dual to operators in the SU(3) sector of the dilatation
operator) to the case when string oscillations or pulsations in S^5 are
allowed. We establish a map between the profile of the leading order string
solution and the structure of the corresponding coherent, ``locally BPS'', SYM
scalar operator. As an application, we explicitly determine the form of the
non-holomorphic operators dual to the pulsating strings. Using action--angle
variables, we also directly compute the energy of pulsating solutions,
simplifying previous treatments.Comment: LaTeX, 50 pages, 1 figure. v2: References added, minor corrections.
54 pages. v3: Few changes. One paragraph added at the end of section 3. 55
page
Citraconate inhibits ACOD1 (IRG1) catalysis, reduces interferon responses and oxidative stress, and modulates inflammation and cell metabolism
Although the immunomodulatory and cytoprotective properties of itaconate have been studied extensively, it is not known
whether its naturally occurring isomers mesaconate and citraconate have similar properties. Here, we show that itaconate
is partially converted to mesaconate intracellularly and that
mesaconate accumulation in macrophage activation depends
on prior itaconate synthesis. When added to human cells in
supraphysiological concentrations, all three isomers reduce
lactate levels, whereas itaconate is the strongest succinate
dehydrogenase (SDH) inhibitor. In cells infected with influenza A virus (IAV), all three isomers profoundly alter amino
acid metabolism, modulate cytokine/chemokine release and
reduce interferon signalling, oxidative stress and the release
of viral particles. Of the three isomers, citraconate is the
strongest electrophile and nuclear factor-erythroid 2-related
factor 2 (NRF2) agonist. Only citraconate inhibits catalysis of
itaconate by cis-aconitate decarboxylase (ACOD1), probably
by competitive binding to the substrate-binding site. These
results reveal mesaconate and citraconate as immunomodulatory, anti-oxidative and antiviral compounds, and citraconate
as the first naturally occurring ACOD1 inhibitor
A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses
We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants
Anomalous dimensions in gauge theories from rotating strings in
Semi-classical soliton solutions for superstrings in are
used to predict the dimension of gauge theory operators in SU(N) SYM
theory. We discuss the possible origin of scaling violations on the gauge
theory side.Comment: 12 pages, harvmac. References added. [JHEP06(2002) 038
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Data collected by the Pierre Auger Observatory through 31 August 2007 showed
evidence for anisotropy in the arrival directions of cosmic rays above the
Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{eV}. The
anisotropy was measured by the fraction of arrival directions that are less
than from the position of an active galactic nucleus within 75 Mpc
(using the V\'eron-Cetty and V\'eron catalog). An updated
measurement of this fraction is reported here using the arrival directions of
cosmic rays recorded above the same energy threshold through 31 December 2009.
The number of arrival directions has increased from 27 to 69, allowing a more
precise measurement. The correlating fraction is , compared
with expected for isotropic cosmic rays. This is down from the early
estimate of . The enlarged set of arrival directions is
examined also in relation to other populations of nearby extragalactic objects:
galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in
hard X-rays by the Swift Burst Alert Telescope. A celestial region around the
position of the radiogalaxy Cen A has the largest excess of arrival directions
relative to isotropic expectations. The 2-point autocorrelation function is
shown for the enlarged set of arrival directions and compared to the isotropic
expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
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