334 research outputs found
Constraints on Parity-Even Time Reversal Violation in the Nucleon-Nucleon System and Its Connection to Charge Symmetry Breaking
Parity-even time reversal violation (TRV) in the nucleon-nucleon interaction
is reconsidered. The TRV -exchange interaction on which recent analyses
of measurements are based is necessarily also charge-symmetry breaking (CSB).
Limits on its strength relative to regular -exchange are
extracted from recent CSB experiments in neutron-proton scattering. The result
(95% CL) is considerably lower than limits
inferred from direct TRV tests in nuclear processes. Properties of
-exchange and limit imposed by the neutron EDM are briefly discussed.Comment: RevTex, 8 pages. Factor ten error in cited neutron EDM corrected,
discussion and two references adde
QED radiative corrections to the decay pi^0 to e^+e^-
We reconsider QED radiative corrections (RC) to the
decay width. One kind of RC investigated earlier has a renormalization group
origin and can be associated with the final state interaction of electron and
positron. It determines the distribution of lepton pair invariant masses in the
whole kinematic region. The other type of RC has a double-logarithmic character
and is related to almost on-mass-shell behavior of the lepton form factors. The
total effect of RC for the decay is estimated to be
3.2% and for the decay is 4.3%.Comment: 12 pages, 3 figure
Energy Dependence of the NN t-matrix in the Optical Potential for Elastic Nucleon-Nucleus Scattering
The influence of the energy dependence of the free NN t-matrix on the optical
potential of nucleon-nucleus elastic scattering is investigated within the
context of a full-folding model based on the impulse approximation. The
treatment of the pole structure of the NN t-matrix, which has to be taken into
account when integrating to negative energies is described in detail. We
calculate proton-nucleus elastic scattering observables for O,
Ca, and Pb between 65 and 200 MeV laboratory energy and study
the effect of the energy dependence of the NN t-matrix. We compare this result
with experiment and with calculations where the center-of-mass energy of the NN
t-matrix is fixed at half the projectile energy. It is found that around 200
MeV the fixed energy approximation is a very good representation of the full
calculation, however deviations occur when going to lower energies (65 MeV).Comment: 11 pages (revtex), 6 postscript figure
Thin Ice Target for O(p,p') experiment
A windowless and self-supporting ice target is described. An ice sheet with a
thickness of 29.7 mg/cm cooled by liquid nitrogen was placed at the target
position of a magnetic spectrometer and worked stably in the O
experiment at MeV. Background-free spectra were obtained.Comment: 14 pages, 4 figures, Nucl. Instr. & Meth. A (in press
A quark model analysis of the charge symmetry breaking in nuclear force
In order to investigate the charge symmetry breaking (CSB) in the short range
part of the nuclear force, we calculate the difference of the masses of the
neutron and the proton, , the difference of the scattering
lengths of the p-p and n-n scatterings, , and the difference of the
analyzing power of the proton and the neutron in the n-p scattering, , by a quark model. In the present model the sources of CSB are the
mass difference of the up and down quarks and the electromagnetic interaction.
We investigate how much each of them contributes to , and . It is found that the contribution of CSB of the
short range part in the nuclear force is large enough to explain the observed
, while is rather underestimated.Comment: 26 pages,6 figure
Off-Shell Rho-Omega Mixing Through Quark Loops With Non-Perturbative Meson Vertex And Quark Mass Functions
The momemtum dependence of the off-shell - mixing amplitude is
calculated through a two-quark loop diagram, using non-perturbative meson-quark
vertex functions for the and mesons, as well as
non-perturbative quark propagators. Both these quantities are generated
self-consistently through an interlinked BSE-cum-SDE approach with a 3D support
for the BSE kernel with two basic constants which are pre- checked against a
wide cross section of both meson and baryon spectra within a common structural
framework for their respective 3D BSE's. With this pre-calibration, the
on-shell strength works out at -2.434 in units of the change in
"constituent mass squared", which is consistent with the to
data for a u-d mass difference of ~4 MeV ,while the relative
off-shell strength (0.99 0.01) lies midway between quark-loop and QCD-SR
results. We also calculate the photon-mediated - propagator whose
off-shell structure has an additional pole at =0. The implications of
these results vis-a-vis related investigations are discussed.Comment: 12 Pages, latex file, NTUTH-94-0
How the recent BABAR data for P to \gamma\gamma* affect the Standard Model predictions for the rare decays P to l+l-
Measuring the lepton anomalous magnetic moments and the rare decays
of light pseudoscalar mesons into lepton pairs , serve as
important tests of the Standard Model. To reduce the theoretical uncertainty in
the standard model predictions, the data on the charge and transition form
factors of the light pseudoscalar mesons play a significant role. Recently, new
data on the behavior of the transition form factors at
large momentum transfer were supplied by the BABAR collaboration. There are
several problems with the theoretical interpretation of these data: 1) An
unexpectedly slow decrease of the pion transition form factor at high momenta,
2) the qualitative difference in the behavior of the pion form factor and the
and form factors at high momenta, 3) the inconsistency of
the measured ratio of the and form factors with the
predicted one. We comment on the influence of the new BABAR data on the rare
decay branchings.Comment: 11 pages, 3 figure
Treatment of Branch Retinal Vein Occlusion induced Macular Edema with Bevacizumab
BACKGROUND: Branch retinal vein occlusion is a frequent cause of visual loss with currently insufficient treatment options. We evaluate the effect of Bevacizumab (Avastin) treatment in patients with macular edema induced by branch retinal vein occlusion. METHODS: Retrospective analysis of 32 eyes in 32 patients with fluorescein angiography proven branch retinal vein occlusion, macular edema and Bevacizumab treatment. Outcome measures were best corrected visual acuity in logMAR and central retinal thickness in OCT. RESULTS: Visual acuity was significantly better 4 to 6 weeks after Bevacizumab treatment compared to visual acuity prior to treatment (before 0.7 +/- 0.3 and after 0.5 +/- 0.3; mean +/- standard deviation; p < 0.01, paired t-test). Gain in visual acuity was accompanied by a significant decrease in retinal thickness (454 +/- 117 to 305 +/- 129 microm, p < 0.01, paired t-test). Follow up (170, 27 - 418 days; median, range) shows that improvement for both visual acuity and retinal thickness last for several months after Bevacizumab use. CONCLUSION: We present evidence that intravitreal Bevacizumab is an effective and lasting treatment for macular edema after branch retinal vein occlusion
Characteristic retinal atrophy pattern allows differentiation between pediatric MOGAD and MS after a single optic neuritis episode.
BACKGROUND
Optic neuritis (ON) is the most prevalent manifestation of pediatric multiple sclerosis (MSped) and myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGADped) in children > 6 years. In this study, we investigated retinal atrophy patterns and diagnostic accuracy of optical coherence tomography (OCT) in differentiating between both diseases after the first ON episode.
METHODS
Patients were retrospectively identified in eight tertial referral centers. OCT, VEP and high/low-contrast visual acuity (HCVA/LCVA) have been investigated > 6 months after the first ON. Prevalence of pathological OCT findings was identified based on data of 144 age-matched healthy controls.
RESULTS
Thirteen MOGADped (10.7 ± 4.2 years, F:M 8:5, 21 ON eyes) and 21 MSped (14.3 ± 2.4 years, F:M 19:2, 24 ON eyes) patients were recruited. We observed a significantly more profound atrophy of both peripapillary and macular retinal nerve fiber layer in MOGADped compared to MSped (pRNFL global: 68.2 ± 16.9 vs. 89.4 ± 12.3 µm, p < 0.001; mRNFL: 0.12 ± 0.01 vs. 0.14 ± 0.01 mm3, p < 0.001). Neither other macular layers nor P100 latency differed. MOGADped developed global atrophy affecting all peripapillary segments, while MSped displayed predominantly temporal thinning. Nasal pRNFL allowed differentiation between both diseases with the highest diagnostic accuracy (AUC = 0.902, cutoff < 62.5 µm, 90.5% sensitivity and 70.8% specificity for MOGADped). OCT was also substantially more sensitive compared to VEP in identification of ON eyes in MOGAD (pathological findings in 90% vs. 14%, p = 0.016).
CONCLUSION
First MOGAD-ON results in a more severe global peripapillary atrophy compared to predominantly temporal thinning in MS-ON. Nasal pRNFL allows differentiation between both diseases with the highest accuracy, supporting the additional diagnostic value of OCT in children with ON
Report and preliminary results of R/V SONNE Cruise SO251 - Extreme events Archived in the GEologial Record of JAPAN's subduction margins (EAGER-JAPAN)
Leg A SO251-1, Yokohama - Yokohama, 04.10.2016 - 15.10.2016, Leg B SO251-2, Yokohama - Yokohama, 18.10.2016 - 02.11.201
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