2,210 research outputs found
Pseudoscalar Meson Mixing in Effective Field Theory
We show that for any effective field theory of colorless meson fields, the
mixing schemes of particle states and decay constants are not only related but
also determined exclusively by the kinetic and mass Lagrangian densities. In
the general case, these are bilinear in terms of the intrinsic fields and
involve non-diagonal kinetic and mass matrices. By applying three consecutive
steps this Lagrangian can be reduced into the standard quadratic form in terms
of the physical fields. These steps are : (i) the diagonalization of the
kinetic matrix, (ii) rescaling of the fields, and (iii) the diagonalization of
the mass matrix. In case, where the dimensions of the non-diagonal kinetic and
mass sub-matrices are respectively, and , this procedure
leads to mixing schemes which involve angles and
field rescaling parameters. This observation holds true irrespective with the
type of particle interactions presumed. The commonly used mixing schemes,
correspond to a proper choice of the kinetic and mass matrices, and are derived
as special cases. In particular, - mixing, requires one angle, if
and only if, the kinetic term with the intrinsic fields has a quadratic form.Comment: REVTeX, 6 page
The Dipion Mass Spectrum In e+e- Annihilation and tau Decay: A Dynamical (rho0, omega, phi) Mixing Approach
We readdress the problem of finding a simultaneous description of the pion
form factor data in e+e- annihilations and in tau decays. For this purpose, we
work in the framework of the Hidden Local Symmetry (HLS) Lagrangian and modify
the vector meson mass term by including the pion and kaon loop contributions.
This leads us to define the physical rho, omega and phi fields as linear
combinations of their ideal partners, with coefficients being meromorphic
functions of s, the square of the 4--momentum flowing into the vector meson
lines. This allows us to define a dynamical, i.e. s-dependent, vector meson
mixing scheme. The model is overconstrained by extending the framework in order
to include the description of all meson radiative (V P gamma and P gamma gamma
couplings) and leptonic (Ve+e- couplings) decays and also the isospin breaking
(omega/ phi --> pi+ pi-) decay modes. The model provides a simultaneous,
consistent and good description of the e+e- and tau dipion spectra. The
expression for pion form factor in the latter case is derived from those in the
former case by switching off the isospin breaking effects specific to e+e- and
switching on those for tau decays. Besides, the model also provides a good
account of all decay modes of the form V P gamma, Pgamma gamma as well as the
isospin breaking decay modes. It leads us to propose new reference values for
the rho^0 --> e+ e- and omega --> pi+ pi- partial widths which are part of our
description of the pion form factor. Other topics (phi --> K anti K, the rho
meson mass and width parameters) are briefly discussed. Therefore, we confirm
the 3.3 sigma discrepancy between the theoretical estimate of a_mu based on
e+e- and its direct BNL measurement.Comment: 71 pages, 8 figures. Accepted by EPJ C. Version 3: correct minor
typos, minor changes spread out into the text. Extension of Sections 12.2 and
12.3.5 and introduction of the new Appendix
Intravitreal ranibizumab and bevacizumab in combination with full-fluence verteporfin therapy and dexamethasone for exudative age-related macular degeneration.
Abstract
PURPOSE:
To evaluate the efficacy and safety of triple therapy with intravitreal anti-vascular-endothelial-growth-factor (VEGF) antibody, dexamethasone and verteporfin photodynamic therapy (PDT) for exudative age-related macular degeneration (AMD).
METHODS:
Retrospective, comparative, interventional study. Records of treatment-naïve patients who received intravitreal bevacizumab or ranibizumab in monotherapy or in combination with dexamethasone and full-fluence verteporfin PDT in triple therapy were reviewed. logMAR visual acuity, foveal thickness (FT) on optical coherence tomography, intraocular pressure and endophthalmitis occurrence were recorded.
RESULTS:
Sixty-one eyes were included in the triple-therapy group, 40 eyes were included in the monotherapy group. The mean follow-up was 14.1 ± 3.4 months in the triple-therapy group and 16.3 ± 4.1 months in the monotherapy group. The triple-therapy group enjoyed a lower total number of treatments (1.92 ± 0.44 vs. 3.12 ± 0.37, p < 0.001) and a longer time before first retreatment (5.4 ± 3.3 vs. 3.6 ± 2.5 months, p = 0.001). A significant improvement of visual acuity and FT was present in both groups during the 12 months following first treatment. No adverse effects were observed.
CONCLUSION:
The combination of intravitreal bevacizumab or ranibizumabwith dexamethasone and full-fluence PDT for exudative AMD provided visual and anatomic improvement and a good safety profile. Triple therapy may reduce the number of retreatments when compared to anti-VEGF alone
Chiral Anomaly and Eta-Eta' Mixing
We determine the mixing angle via a procedure relatively
independent of theoretical assumptions by simultaneously fitting
reactions involving the anomaly--.
We extract reasonably precise renormalized values of the octet and singlet
pseudoscalar decay constants as well as the mixing angle .Comment: 12 page standard Latex file, three figures, added comment
Finding undetected protein associations in cell signaling by belief propagation
External information propagates in the cell mainly through signaling cascades
and transcriptional activation, allowing it to react to a wide spectrum of
environmental changes. High throughput experiments identify numerous molecular
components of such cascades that may, however, interact through unknown
partners. Some of them may be detected using data coming from the integration
of a protein-protein interaction network and mRNA expression profiles. This
inference problem can be mapped onto the problem of finding appropriate optimal
connected subgraphs of a network defined by these datasets. The optimization
procedure turns out to be computationally intractable in general. Here we
present a new distributed algorithm for this task, inspired from statistical
physics, and apply this scheme to alpha factor and drug perturbations data in
yeast. We identify the role of the COS8 protein, a member of a gene family of
previously unknown function, and validate the results by genetic experiments.
The algorithm we present is specially suited for very large datasets, can run
in parallel, and can be adapted to other problems in systems biology. On
renowned benchmarks it outperforms other algorithms in the field.Comment: 6 pages, 3 figures, 1 table, Supporting Informatio
Vector meson dominance and the rho meson
We discuss the properties of vector mesons, in particular the rho^0, in the
context of the Hidden Local Symmetry (HLS) model. This provides a unified
framework to study several aspects of the low energy QCD sector. Firstly, we
show that in the HLS model the physical photon is massless, without requiring
off field diagonalization. We then demonstrate the equivalence of HLS and the
two existing representations of vector meson dominance, VMD1 and VMD2, at both
tree level and one loop order. Finally the S matrix pole position is shown to
provide a model and process independent means of specifying the rho mass and
width, in contrast to the real axis prescription currently used in the Particle
Data Group tables.Comment: 18 pages, REVTE
R-values in Low Energy e^+e^- Annihilation
This presentation briefly summarizes the recent measurements of R-values in
low energy e^+e^- annihilation. The new experiments aimed at reducing the
uncertainties in R-values and performed with the upgraded Beijing Spectrometer
(BESII) at Beijing Electron Positron Collider (BEPC) in Beijing and with CMD-2
and SND at VEEP-2M in Novosibirsk are reviewed and discussed.Comment: 17 pages, 10 figures, invited presentation at the XIX International
Symposium on Lepton and Photon Interactions at High Energy, Stanford
University, August 199
Tri-meson-mixing of -- and -- in the light-cone quark model
The radiative transition form factors of the pseudoscalar mesons {,
, } and the vector mesons {, , } are restudied
with -- and -- in tri-meson-mixing
pattern, which is described by tri-mixing matrices in the light-cone
constituent quark model. The experimental transition decay widths are better
reproduced with tri-meson-mixing than previous results in a two-mixing-angle
scenario of only two-meson - mixing and - mixing.Comment: 8 pages, 6 figures, final version to appear in EPJ
Lubrication and wear protection of micro-structured hydrogels using bioinspired fluids
We report the fabrication and the use of a bioinspired synovial fluid acting as a lubricant fluid
and anti-wear agent at soft and porous chitosan hydrogel tribopairs. This synthetic synovial
fluid is composed of sodium hyaluronate (HA) and a bottle-brush polymer (BB) having a
polycationic attachment group and polyzwitterionic pendant chains. 2.5 %w/w chitosan
hydrogel plugs are organized in a bilayered structure exposing a thin and dense superficial
zone (SZ), covering a porous deep zone (DZ) and exhibiting microchannels perpendicularly
aligned to the SZ. Using a low-load tribometer, the addition of HA lubricating solution at the
hydrogel-hydrogel rubbing contact drastically decreased the coefficient of friction (CoF) from
μ = 0.20 ± 0.01 to μ = 0.04 ± 0.01 on the DZ configuration and from μ = 0.31 ± 0.01 to μ =
0.08 ± 0.01 on the SZ surface when increasing HA concentration from 0 to 1000 μg/mL and
its molecular mass from 10 to 1500 kDa, similar to what was found when using BB polymer
alone. When combining the BB polymer and the 1500 kDa HA, the CoF remained stable at μ
= 0.04 ± 0.01 for both studied contact configurations, highlighting the synergistic interaction
of the two macromolecules. Hydrogel wear was characterized by assessing the final gel
surface roughness by the means of an interferometer. Increasing HA concentration and
molecular weight plus the addition of BB polymer lead to a dramatic surface wear protection
with a final gel surface roughness of the hydrogels similar to the untested gels. In brief, BB
polymer in combination with high molecular weight HA is a potential lubricating fluid as well
as a wear resistant agent for soft materials lubrication and wear protection
Wear protection without surface modification using a synergistic mixture of molecular brushes and linear polymers
We describe the design of lubricating and wear protecting fluids based on mixtures of bottlebrushes (BB) and linear polymers solutions. To illustrate this concept we used hyaluronic acid (HA) - a naturally occurring linear polyelectrolyte, and a water soluble synthetic BB polymer. Individually, these two polymers exhibit poor wear protecting capabilities compared to saline solutions. Mixture of the two polymers in pure water or in saline allows to drastically increase wear protection of surfaces over a wide range of shearing conditions. We demonstrate that this synergy between the BB and HA polymers emerges from a strong cohesion between the two components forming the boundary film due to entanglements between both polymers. We show that this concept can be applied to other types of linear polymers and surfaces and is independent of the chemical and mechanical properties of the surfaces
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