1,973 research outputs found
Cascades with Adjoint Matter: Adjoint Transitions
A large class of duality cascades based on quivers arising from non-isolated
singularities enjoy adjoint transitions - a phenomenon which occurs when the
gauge coupling of a node possessing adjoint matter is driven to strong coupling
in a manner resulting in a reduction of rank in the non-Abelian part of the
gauge group and a subsequent flow to weaker coupling. We describe adjoint
transitions in a simple family of cascades based on a Z2-orbifold of the
conifold using field theory. We show that they are dual to Higgsing and produce
varying numbers of U(1) factors, moduli, and monopoles in a manner which we
calculate. This realizes a large family of cascades which proceed through
Seiberg duality and Higgsing. We briefly describe the supergravity limit of our
analysis, as well as a prescription for treating more general theories. A
special role is played by N=2 SQCD. Our results suggest that additional light
fields are typically generated when UV completing certain constructions of
spontaneous supersymmetry breaking into cascades, potentially leading to
instabilities.Comment: 29 pages, a few typos fixed, improved discussion, added figure; now
there is 1 figur
Z-extremization and F-theorem in Chern-Simons matter theories
The three dimensional exact R symmetry of N=2 SCFTs extremizes the partition
function localized on a three sphere. Here we verify this statement at weak
coupling. We give a detailed analysis for two classes of models. The first one
is an SU(N)_k gauge theory at large k with both fundamental and adjoint matter
fields, while the second is a flavored version of the ABJ theory, where the CS
levels are large but they do not necessarily sum up to zero. We study in both
cases superpotential deformations and compute the R charges at different fixed
points. When these fixed points are connected by an RG flow we explicitly
verify that the free energy decreases at the endpoints of the flow between the
fixed points, corroborating the conjecture of an F-theorem in three dimensions.Comment: 28 pages, 3 figures, JHEP.cls, minor corrections, references adde
Remarks on quiver gauge theories from open topological string theory
We study effective quiver gauge theories arising from a stack of D3-branes on certain Calabi-Yau singularities. Our point of view is a first principle approach via open topological string theory. This means that we construct the natural A-infinity-structure of open string amplitudes in the associated D-brane category. Then we show that it precisely reproduces the results of the method of brane tilings, without having to resort to any effective field theory computations. In particular, we prove a general and simple formula for effective superpotentials
Kinetic modelling of competition and depletion of shared miRNAs by competing endogenous RNAs
Non-conding RNAs play a key role in the post-transcriptional regulation of
mRNA translation and turnover in eukaryotes. miRNAs, in particular, interact
with their target RNAs through protein-mediated, sequence-specific binding,
giving rise to extended and highly heterogeneous miRNA-RNA interaction
networks. Within such networks, competition to bind miRNAs can generate an
effective positive coupling between their targets. Competing endogenous RNAs
(ceRNAs) can in turn regulate each other through miRNA-mediated crosstalk.
Albeit potentially weak, ceRNA interactions can occur both dynamically,
affecting e.g. the regulatory clock, and at stationarity, in which case ceRNA
networks as a whole can be implicated in the composition of the cell's
proteome. Many features of ceRNA interactions, including the conditions under
which they become significant, can be unraveled by mathematical and in silico
models. We review the understanding of the ceRNA effect obtained within such
frameworks, focusing on the methods employed to quantify it, its role in the
processing of gene expression noise, and how network topology can determine its
reach.Comment: review article, 29 pages, 7 figure
Adalimumab in Patients with Active Noninfectious Uveitis
BACKGROUND:
Patients with noninfectious uveitis are at risk for long-term complications of uncontrolled
inflammation, as well as for the adverse effects of long-term glucocorticoid
therapy. We conducted a trial to assess the efficacy and safety of adalimumab as a
glucocorticoid-sparing agent for the treatment of noninfectious uveitis.
METHODS:
This multinational phase 3 trial involved adults who had active noninfectious intermediate
uveitis, posterior uveitis, or panuveitis despite having received prednisone treatment
for 2 or more weeks. Investigators and patients were unaware of the study-group
assignments. Patients were randomly assigned in a 1:1 ratio to receive adalimumab
(a loading dose of 80 mg followed by a dose of 40 mg every 2 weeks) or matched
placebo. All patients received a mandatory prednisone burst followed by tapering of
prednisone over the course of 15 weeks. The primary efficacy end point was the time
to treatment failure occurring at or after week 6. Treatment failure was a multicomponent
outcome that was based on assessment of new inflammatory lesions, best
corrected visual acuity, anterior chamber cell grade, and vitreous haze grade. Nine
ranked secondary efficacy end points were assessed, and adverse events were reported.
RESULTS:
The median time to treatment failure was 24 weeks in the adalimumab group and 13
weeks in the placebo group. Among the 217 patients in the intention-to-treat population,
those receiving adalimumab were less likely than those in the placebo group to
have treatment failure (hazard ratio, 0.50; 95% confidence interval, 0.36 to 0.70;
P<0.001). Outcomes with regard to three secondary end points (change in anterior
chamber cell grade, change in vitreous haze grade, and change in best corrected visual
acuity) were significantly better in the adalimumab group than in the placebo
group. Adverse events and serious adverse events were reported more frequently
among patients who received adalimumab (1052.4 vs. 971.7 adverse events and 28.8
vs. 13.6 serious adverse events per 100 person-years).
CONCLUSIONS:
In our trial, adalimumab was found to be associated with a lower risk of uveitic flare
or visual impairment and with more adverse events and serious adverse events than
was placebo
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, with a significance of
2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html,
link to supplemental material inserted in the reference
Multifield Dynamics in Higgs-otic Inflation
In Higgs-otic inflation a complex neutral scalar combination of the and
MSSM Higgs fields plays the role of inflaton in a chaotic fashion. The
potential is protected from large trans-Planckian corrections at large inflaton
if the system is embedded in string theory so that the Higgs fields parametrize
a D-brane position. The inflaton potential is then given by a DBI+CS D-brane
action yielding an approximate linear behaviour at large field. The inflaton
scalar potential is a 2-field model with specific non-canonical kinetic terms.
Previous computations of the cosmological parameters (i.e. scalar and tensor
perturbations) did not take into account the full 2-field character of the
model, ignoring in particular the presence of isocurvature perturbations and
their coupling to the adiabatic modes. It is well known that for generic
2-field potentials such effects may significantly alter the observational
signatures of a given model. We perform a full analysis of adiabatic and
isocurvature perturbations in the Higgs-otic 2-field model. We show that the
predictivity of the model is increased compared to the adiabatic approximation.
Isocurvature perturbations moderately feed back into adiabatic fluctuations.
However, the isocurvature component is exponentially damped by the end of
inflation. The tensor to scalar ratio varies in a region ,
consistent with combined Planck/BICEP results.Comment: 35 pages, 11 figure
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Animal welfare in studies on murine tuberculosis : assessing progress over a 12-year period and the need for further improvement
There is growing concern over the welfare of animals used in research, in particular when these animals develop pathology. The present study aims to identify the main sources of animal distress and to assess the possible implementation of refinement measures in experimental infection research, using mouse models of tuberculosis (TB) as a case study. This choice is based on the historical relevance of mouse studies in understanding the disease and the present and long-standing impact of TB on a global scale. Literature published between 1997 and 2009 was analysed, focusing on the welfare impact on the animals used and the implementation of refinement measures to reduce this impact. In this 12-year period, we observed a rise in reports of ethical approval of experiments. The proportion of studies classified into the most severe category did however not change significantly over the studied period. Information on important research parameters, such as method for euthanasia or sex of the animals, were absent in a substantial number of papers. Overall, this study shows that progress has been made in the application of humane endpoints in TB research, but that a considerable potential for improvement remains.Nuno H. Franco is funded by Fundação para a Ciência e Tecnologia (SFRH/BD/38337/2007). This work is funded by FEDER funds through the Operational Competitiveness Programme - COMPETE and by national funds through FCT - Fundação para a Ciência e Tecnologia under the project FCOMP-01-0124-FEDER-022718 (PEst-C/SAU/LA0002/2011
Heteroreceptor complexes formed by dopamine D1, histamine H3 and N-methyl-D-aspartate glutamate receptors as targets to prevent neuronal death in Alzheimer's disease
Alzheimer’s disease (AD) is a neurodegenerative disorder causing progressive memory loss and cognitive dysfunction. Anti-AD strategies targeting cell receptors consider them as isolated units. However, many cell surface receptors cooperate and physically contact each other forming complexes having different biochemical properties than individual receptors. We here report the discovery of dopamine D , histamine H , and N-methylD-aspartate (NMDA) glutamate receptor heteromers in heterologous systems and in rodent brain cortex. Heteromers were detected by coimmunoprecipitation and in situ proximity ligation assays (PLA) in the rat cortex where H receptor agonists, via negative cross-talk, and H receptor antagonists, via cross-antagonism, decreased D receptor agonist signaling determined by ERK1/2 or Akt phosphorylation and counteracted D receptormediated excitotoxic cell death. Both D and H receptor antagonists also counteracted NMDA toxicity suggesting a complex interaction between NMDA receptors and D -H receptor heteromer function. Likely due to heteromerization, H receptors act as allosteric regulator for D and NMDA receptors. By bioluminescence resonance energy transfer (BRET), we demonstrated that D or H receptors form heteromers with NR1A/NR2B NMDA receptor subunits. D -H -NMDA receptor complexes were confirmed by BRET combined with fluorescence complementation. The endogenous expression of complexes in mouse cortex was determined by PLA and similar expression was observed in wild-type and APP/PS1 mice. Consistent with allosteric receptor-receptor interactions within the complex, H receptor antagonists reduced NMDA or D receptor-mediated excitotoxic cell death in cortical organotypic cultures. Moreover, H receptor antagonists reverted the toxicity induced by ß -amyloid peptide. Thus, histamine H receptors in D -H -NMDA heteroreceptor complexes arise as promising targets to prevent neurodegeneration
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