118 research outputs found
Dynamically generated resonances from the vector octet-baryon decuplet interaction
We study the interaction of the octet of vector mesons with the decuplet of
baryons using Lagrangians of the hidden gauge theory for vector interactions.
The unitary amplitudes in coupled channels develop poles that can be associated
with some known baryonic resonances, while there are predictions for new ones
at the energy frontier of the experimental research. The work offers guidelines
on how to search for these resonances
DN interaction from meson exchange
A model of the DN interaction is presented which is developed in close
analogy to the meson-exchange KbarN potential of the Juelich group utilizing
SU(4) symmetry constraints. The main ingredients of the interaction are
provided by vector meson (rho, omega) exchange and higher-order box diagrams
involving D*N, D\Delta, and D*\Delta intermediate states. The coupling of DN to
the pi-Lambda_c and pi-Sigma_c channels is taken into account. The interaction
model generates the Lambda_c(2595) resonance dynamically as a DN quasi-bound
state. Results for DN total and differential cross sections are presented and
compared with predictions of an interaction model that is based on the
leading-order Weinberg-Tomozawa term. Some features of the Lambda_c(2595)
resonance are discussed and the role of the near-by pi-Sigma_c threshold is
emphasized. Selected predictions of the orginal KbarN model are reported too.
Specifically, it is pointed out that the model generates two poles in the
partial wave corresponding to the Lambda(1405) resonance.Comment: 14 pages, 8 figure
Effects of a partially supervised conditioning programme in cystic fibrosis: an international multi-centre randomised controlled trial (ACTIVATE-CF): study protocol
Physical activity (PA) and exercise have become an accepted and valued component of cystic fibrosis (CF) care. Regular PA and exercise can positively impact pulmonary function, improve physical fitness, and enhance health-related quality of life (HRQoL). However, motivating people to be more active is challenging. Supervised exercise programs are expensive and labour intensive, and adherence falls off significantly once supervision ends. Unsupervised or partially supervised programs are less costly and more flexible, but compliance can be more problematic. The primary objective of this study is to evaluate the effects of a partially supervised exercise intervention along with regular motivation on forced expiratory volume in 1 s (FEV1) at 6 months in a large international group of CF patients. Secondary endpoints include patient reported HRQoL, as well as levels of anxiety and depression, and control of blood sugar.; It is planned that a total of 292 patients with CF 12 years and older with a FEV1 ≥ 35% predicted shall be randomised. Following baseline assessments (2 visits) patients are randomised into an intervention and a control group. Thereafter, they will be seen every 3 months for assessments in their centre for one year (4 follow-up visits). Along with individual counselling to increase vigorous PA by at least 3 h per week on each clinic visit, the intervention group documents daily PA and inactivity time and receives a step counter to record their progress within a web-based diary. They also receive monthly phone calls from the study staff during the first 6 months of the study. After 6 months, they continue with the step counter and web-based programme for a further 6 months. The control group receives standard care and keeps their PA level constant during the study period. Thereafter, they receive the intervention as well.; This is the first large, international multi-centre study to investigate the effects of a PA intervention in CF with motivational feedback on several health outcomes using modern technology. Should this relatively simple programme prove successful, it will be made available on a wider scale internationally.; ClinicalTrials.gov Identifier: NCT01744561 ; Registration date: December 6, 2012
Embedded pitch adapters: a high-yield interconnection solution for strip sensors
A proposal to fabricate large area strip sensors with integrated, or embedded, pitch adapters is presented for the End-cap part of the Inner Tracker in the ATLAS experiment. To implement the embedded pitch adapters, a second metal layer is used in the sensor fabrication, for signal routing to the ASICs. Sensors with different embedded pitch adapters have been fabricated in order to optimize the design and technology. Inter-strip capacitance, noise, pick-up, cross-talk, signal efficiency, and fabrication yield have been taken into account in their design and fabrication. Inter-strip capacitance tests taking into account all channel neighbors reveal the important differences between the various designs considered. These tests have been correlated with noise figures obtained in full assembled modules, showing that the tests performed on the bare sensors are a valid tool to estimate the final noise in the full module. The full modules have been subjected to test beam experiments in order to evaluate the incidence of cross-talk, pick-up, and signal loss. The detailed analysis shows no indication of cross-talk or pick-up as no additional hits can be observed in any channel not being hit by the beam above 170 mV threshold, and the signal in those channels is always below 1% of the signal recorded in the channel being hit, above 100 mV threshold. First results on irradiated mini-sensors with embedded pitch adapters do not show any change in the interstrip capacitance measurements with only the first neighbors connected
Evaluation of the performance of irradiated silicon strip sensors for the forward detector of the ATLAS Inner Tracker Upgrade
The upgrade to the High-Luminosity LHC foreseen in about ten years represents a great challenge for the ATLAS inner tracker and the silicon strip sensors in the forward region. Several strip sensor designs were developed by the ATLAS collaboration and fabricated by Hamamatsu in order to maintain enough performance in terms of charge collection efficiency and its uniformity throughout the active region. Of particular attention, in the case of a stereo-strip sensor, is the area near the sensor edge where shorter strips were ganged to the complete ones. In this work the electrical and charge collection test results on irradiated miniature sensors with forward geometry are presented. Results from charge collection efficiency measurements show that at the maximum expected fluence, the collected charge is roughly halved with respect to the one obtained prior to irradiation. Laser measurements show a good signal uniformity over the sensor. Ganged strips have a similar efficiency as standard strips
A precise measurement of the magnetic field in the corona of the black hole binary V404 Cygni
Observations of binary stars containing an accreting black hole or neutron star often show x-ray emission extending to high energies (>10 kilo–electron volts), which is ascribed to an accretion disk corona of energetic particles akin to those seen in the solar corona. Despite their ubiquity, the physical conditions in accretion disk coronae remain poorly constrained. Using simultaneous infrared, optical, x-ray, and radio observations of the Galactic black hole system V404 Cygni, showing a rapid synchrotron cooling event in its 2015 outburst, we present a precise 461 ± 12 gauss magnetic field measurement in the corona. This measurement is substantially lower than previous estimates for such systems, providing constraints on physical models of accretion physics in black hole and neutron star binary systems.
This article has a correction. Please see: http://science.sciencemag.org/content/360/6386/eaat927
A Yersinia Effector with Enhanced Inhibitory Activity on the NF-κB Pathway Activates the NLRP3/ASC/Caspase-1 Inflammasome in Macrophages
A type III secretion system (T3SS) in pathogenic Yersinia
species functions to translocate Yop effectors, which modulate cytokine
production and regulate cell death in macrophages. Distinct pathways of
T3SS-dependent cell death and caspase-1 activation occur in
Yersinia-infected macrophages. One pathway of cell death
and caspase-1 activation in macrophages requires the effector YopJ. YopJ is an
acetyltransferase that inactivates MAPK kinases and IKKβ to cause
TLR4-dependent apoptosis in naïve macrophages. A YopJ isoform in Y.
pestis KIM (YopJKIM) has two amino acid substitutions,
F177L and K206E, not present in YopJ proteins of Y.
pseudotuberculosis and Y. pestis CO92. As compared
to other YopJ isoforms, YopJKIM causes increased apoptosis, caspase-1
activation, and secretion of IL-1β in Yersinia-infected
macrophages. The molecular basis for increased apoptosis and activation of
caspase-1 by YopJKIM in Yersinia-infected
macrophages was studied. Site directed mutagenesis showed that the F177L and
K206E substitutions in YopJKIM were important for enhanced apoptosis,
caspase-1 activation, and IL-1β secretion. As compared to
YopJCO92, YopJKIM displayed an enhanced capacity to
inhibit phosphorylation of IκB-α in macrophages and to bind IKKβ in
vitro. YopJKIM also showed a moderately increased ability to inhibit
phosphorylation of MAPKs. Increased caspase-1 cleavage and IL-1β secretion
occurred in IKKβ-deficient macrophages infected with Y.
pestis expressing YopJCO92, confirming that the
NF-κB pathway can negatively regulate inflammasome activation.
K+ efflux, NLRP3 and ASC were important for secretion of
IL-1β in response to Y. pestis KIM infection as shown using
macrophages lacking inflammasome components or by the addition of exogenous KCl.
These data show that caspase-1 is activated in naïve macrophages in
response to infection with a pathogen that inhibits IKKβ and MAPK kinases
and induces TLR4-dependent apoptosis. This pro-inflammatory form of apoptosis
may represent an early innate immune response to highly virulent pathogens such
as Y. pestis KIM that have evolved an enhanced ability to
inhibit host signaling pathways
Conservation of Salmonella Infection Mechanisms in Plants and Animals
Salmonella virulence in animals depends on effectors injected by Type III Secretion Systems (T3SSs). In this report we demonstrate that Salmonella mutants that are unable to deliver effectors are also compromised in infection of Arabidopsis thaliana plants. Transcriptome analysis revealed that in contrast to wild type bacteria, T3SS mutants of Salmonella are compromised in suppressing highly conserved Arabidopsis genes that play a prominent role during Salmonella infection of animals. We also found that Salmonella originating from infected plants are equally virulent for human cells and mice. These results indicate a high degree of conservation in the defense and infection mechanism of animal and plant hosts during Salmonella infection
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