8,802 research outputs found
Emerging insights on intestinal dysbiosis during bacterial infections
Infection of the gastrointestinal tract is commonly linked to pathological imbalances of the resident microbiota, termed dysbiosis. In recent years, advanced high-throughput genomic approaches have allowed us to examine the microbiota in an unprecedented manner, revealing novel biological insights about infection-associated dysbiosis at the community and individual species levels. A dysbiotic microbiota is typically reduced in taxonomic diversity and metabolic function, and can harbour pathobionts that exacerbate intestinal inflammation or manifest systemic disease. Dysbiosis can also promote pathogen genome evolution, while allowing the pathogens to persist at high density and transmit to new hosts. A deeper understanding of bacterial pathogenicity in the context of the intestinal microbiota should unveil new approaches for developing diagnostics and therapies for enteropathogens
mixing effects on charmonium and meson decays
We include the meson into the -- mixing formalism
constructed in our previous work, where represents the pseudoscalar
gluball. The mixing angles in this tetramixing matrix are constrained by
theoretical and experimental implications from relevant hadronic processes.
Especially, the angle between and is found to be about
from the measured decay widths of the meson. The pseudoscalar glueball
mass , the pseudoscalar densities and the U(1) anomaly
matrix elements associated with the mixed states are solved from the anomalous
Ward identities. The solution GeV obtained from the
-- mixing is confirmed, while grows to above the pion
mass, and thus increases perturbative QCD predictions for the branching ratios
. We then analyze the -mixing effects on charmonium
magnetic dipole transitions, and on the branching
ratios and CP asymmetries, which further improve the consistency between
theoretical predictions and data. A predominant observation is that the
mixing enhances the perturbative QCD predictions for
by 18%, but does not alter those for . The puzzle due to the
large data is then resolved.Comment: 12 pages, version to appear in PR
Spectral Theory for Non-linear Superconducting Microwave Systems: Extracting Relaxation Rates and Mode Hybridization
The accurate modeling of mode hybridization and calculation of radiative
relaxation rates have been crucial to the design and optimization of
superconducting quantum devices. In this work, we introduce a spectral theory
for the electrohydrodynamics of superconductors that enables the extraction of
the relaxation rates of excitations in a general three-dimensional distribution
of superconducting bodies. Our approach addresses the long-standing problem of
formulating a modal description of open systems that is both efficient and
allows for second quantization of the radiative hybridized fields. This is
achieved through the implementation of finite but transparent boundaries
through which radiation can propagate into and out of the computational domain.
The resulting spectral problem is defined within a coarse-grained formulation
of the electrohydrodynamical equations that is suitable for the analysis of the
non-equilibrium dynamics of multiscale superconducting quantum systems.Comment: 21 pages, 12 figures, journal pape
Disorder in a Quantum Critical Superconductor
In four classes of materials, the layered copper-oxides, organics,
iron-pnictides and heavy-fermion compounds, an unconventional superconducting
state emerges as a magnetic transition is tuned toward absolute zero
temperature, that is, toward a magnetic quantum-critical point (QCP). In most
materials, the QCP is accessed by chemical substitutions or applied pressure.
CeCoIn5 is one of the few materials that are born as a quantum-critical
superconductor and, therefore, offers the opportunity to explore the
consequences of chemical disorder. Cadmium-doped crystals of CeCoIn5 are a
particularly interesting case where Cd substitution induces long-range magnetic
order, as in Zn-doped copper-oxides. Applied pressure globally supresses the
Cd-induced magnetic order and restores bulk superconductivity. Here we show,
however, that local magnetic correlations, whose spatial extent decreases with
applied pressure, persist at the extrapolated QCP. The residual droplets of
impurity-induced magnetic moments prevent the reappearance of conventional
signatures of quantum criticality, but induce a heterogeneous electronic state.
These discoveries show that spin droplets can be a source of electronic
heterogeneity in classes of strongly correlated electron systems and emphasize
the need for caution when interpreting the effects of tuning a correlated
system by chemical substitution.Comment: main text and supplementary informatio
Wave-current interactions in marine current turbines
The influence of waves on the dynamic properties of bending moments at the root of blades of tidal stream vertical-axis rotors is reported. Blade element-momentum theory for wind turbines is combined with linear wave theory and used to analyze this influence. Experiments were carried out with a 350 mm diameter rotor to validate the simulation and the comparison shows the ability of the theoretical approach to predict the blade root bending moments. It can be concluded that, in steep waves, linear theory underestimates the dynamic behaviour of bending moments. However, in long waves, linear theory works well. Bending moments at roots of rotor blades fluctuate with significant amplitudes (as much as 50 per cent of mean value for out-of-plane bending moment and 100 per cent of mean value for in-plane bending moment), which will be important for design of tidal stream rotors
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