1,308 research outputs found
Moving beyond e-journals
Paul Ayris explains to Elspeth Hyams why scholarly communication has moved beyond the debate on e-journals pricing and open access
btn1, the Schizosaccharomyces pombe homologue of the human Batten disease gene CLN3, regulates vacuole homeostasis
International audienc
Masses and widths of scalar-isoscalar multi-channel resonances from data analysis
Peculiarities of obtaining parameters for broad multi-channel resonances from
data are discussed analyzing the experimental data on processes
in the channel in a
model-independent approach based on analyticity and unitarity and using an
uniformization procedure. We show that it is possible to obtain a good
description of the scattering data from the threshold to 1.89 GeV with
parameters of resonances cited in the PDG tables as preferred. However, in this
case, first, representation of the background is unsatisfactory;
second, the data on the coupled process are not well
described even qualitatively above 1.15 GeV when using the resonance parameters
from the only scattering analysis. The combined analysis of these
coupled processes is needed, which is carried out satisfactorily. Then both
above-indicated flaws, related to the analysis of solely the
-scattering, are cured. The most remarkable change of parameters with
respect to the values of only scattering analysis appears for the mass
of the which is now in some accordance with the Weinberg prediction
on the basis of mended symmetry and with an analysis using the large-
consistency conditions between the unitarization and resonance saturation. The
obtained -scattering length in case when we restrict to the
analysis of the scattering or consider so-called A-solution (with a
lower mass and width of meson) agrees well with prediction of chiral
perturbation theory (ChPT) and with data extracted at CERN by the NA48/2
Collaboration from the analysis of the decay and by the DIRAC
Collaboration from the measurement of the lifetime.Comment: 21 pages, 3 figures, 6 table
A low-lying scalar meson nonet in a unitarized meson model
A unitarized nonrelativistic meson model which is successful for the
description of the heavy and light vector and pseudoscalar mesons yields, in
its extension to the scalar mesons but for the same model parameters, a
complete nonet below 1 GeV. In the unitarization scheme, real and virtual
meson-meson decay channels are coupled to the quark-antiquark confinement
channels. The flavor-dependent harmonic-oscillator confining potential itself
has bound states epsilon(1.3 GeV), S(1.5 GeV), delta(1.3 GeV), kappa(1.4 GeV),
similar to the results of other bound-state qqbar models. However, the full
coupled-channel equations show poles at epsilon(0.5 GeV), S(0.99 GeV),
delta(0.97 GeV), kappa(0.73 GeV). Not only can these pole positions be
calculated in our model, but also cross sections and phase shifts in the
meson-scattering channels, which are in reasonable agreement with the available
data for pion-pion, eta-pion and Kaon-pion in S-wave scattering.Comment: A slightly revised version of Zeitschrift fuer Physik C30, 615 (1986
Second Cluster Integral and Excluded Volume Effects for the Pion Gas
The quantum mechanical formula for Mayer's second cluster integral for the
gas of relativistic particles with hard-core interaction is derived. The proper
pion volume calculated with quantum mechanical formula is found to be an order
of magnitude larger than its classical evaluation.
The second cluster integral for the pion gas is calculated in quantum
mechanical approach with account for both attractive and hard-core repulsive
interactions. It is shown that, in the second cluster approximation, the
repulsive pion-pion-interactions as well as the finite width of resonances give
important but almost canceling contributions. In contrast, an appreciable
deviation from the ideal gas of pions and pion resonances is observed beyond
the second cluster approximation in the framework of the Van der Waals
excluded-volume model.Comment: 29 pages, Latex, 9 PS-figure
Infliximab in paediatric inflammatory bowel disease
AbstractInfliximab has been widely used in paediatric Crohn's disease, mainly in luminal and fistulous disease refractory to standard treatment and for extraintestinal manifestations. Moreover, there is growing experience with its use in refractory ulcerative colitis. Infliximab has shown similar efficacy and safety in children as in adult population. It is postulated that its early use in paediatric inflammatory bowel disease, as a bridging treatment until the onset of action of other immunomodulators, could reduce the use of steroids and change the natural history of the disease as well. The effect of infliximab on mucosal healing could also contribute to the normal growth and sexual maturation in these patients
On the precision of chiral-dispersive calculations of scattering
We calculate the combination (the Olsson sum rule)
and the scattering lengths and effective ranges , and ,
dispersively (with the Froissart--Gribov representation) using, at
low energy, the phase shifts for scattering obtained by Colangelo,
Gasser and Leutwyler (CGL) from the Roy equations and chiral perturbation
theory, plus experiment and Regge behaviour at high energy, or directly, using
the CGL parameters for s and s. We find mismatch, both among the CGL
phases themselves and with the results obtained from the pion form factor. This
reaches the level of several (2 to 5) standard deviations, and is essentially
independent of the details of the intermediate energy region ( GeV) and, in some cases, of the high energy behaviour assumed. We discuss
possible reasons for this mismatch, in particular in connection with an
alternate set of phase shifts.Comment: Version to appear in Phys. Rev. D. Graphs and sum rule added. Plain
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