8,699 research outputs found
Role of the (1535) in the and reactions
We study the and
reactions with a unitary chiral approach. We find that the unitary chiral
approach, which generates the dynamically, can describe the data
reasonably well, particularly the ratio of the integrated cross sections. This
study provides further support for the unitary chiral description of the
. We also discuss some subtle differences between the coupling
constants determined from the unitary chiral approach and those determined from
phenomenological studies.Comment: version to appear in PRC; certain features of the approach clarifie
Testing the nature of the (1520) in the and reactions
We study the reactions and
with a unitary chiral approach. We
predict the ratio of the invariant mass distributions of these two reactions at
the peak position, which is free of the unknown production
mechanism and reflects only the properties of the . An
experimental measurement of this ratio will provide the couplings of the
to its decay channels, allowing to test the predictions of the
chiral unitary approach on this resonance, which appears as dynamically
generated in that approach.Comment: 7 pages, 6 figures, version to appear in EPJ
Long-term vascular access ports as a means of sedative administration in a rodent fMRI survival model
The purpose of this study is to develop a rodent functional magnetic resonance imaging (fMRI) survival model with the use of heparin-coated vascular access devices. Such a model would ease the administration of sedative agents, reduce the number of animals required in survival experiments and eliminate animal-to-animal variability seen in previous designs. Seven male Sprague-Dawley rats underwent surgical placement of an MRI-compatible vascular access port, followed by implantable electrode placement on the right median nerve. Functional MRI during nerve stimulation and resting-state functional connectivity MRI (fcMRI) were performed at times 0, 2, 4, 8 and 12 weeks postoperatively using a 9.4 T scanner. Anesthesia was maintained using intravenous dexmedetomidine and reversed using atipamezole. There were no fatalities or infectious complications during this study. All vascular access ports remained patent. Blood oxygen level dependent (BOLD) activation by electrical stimulation of the median nerve using implanted electrodes was seen within the forelimb sensory region (S1FL) for all animals at all time points. The number of activated voxels decreased at time points 4 and 8 weeks, returning to a normal level at 12 weeks, which is attributed to scar tissue formation and resolution around the embedded electrode. The applications of this experiment extend far beyond the scope of peripheral nerve experimentation. These vascular access ports can be applied to any survival MRI study requiring repeated medication administration, intravenous contrast, or blood sampling
Successful orthotopic liver transplantation in an adult patient with sickle cell disease and review of the literature
Sickle cell disease can lead to hepatic complications ranging from acute hepatic crises to chronic liver disease including intrahepatic cholestasis, and iron overload. Although uncommon, intrahepatic cholestasis may be severe and medical treatment of this complication is often ineffective. We report a case of a 37 year-old male patient with sickle cell anemia, who developed liver failure and underwent successful orthotopic liver transplantation. Both pre and post-operatively, he was maintained on red cell transfusions. He remains stable with improved liver function 42 months post transplant. The role for orthotopic liver transplantation is not well defined in patients with sickle cell disease, and the experience remains limited. Although considerable challenges of post-transplant graft complications remain, orthotopic liver transplantation should be considered as a treatment option for sickle cell disease patients with end-stage liver disease who have progressed despite conventional medical therapy. An extended period of red cell transfusion support may lessen the post-operative complications
The , , , , and as dynamically generated states from vector meson - vector meson interaction
We report on some recent developments in understanding the nature of the
low-lying mesonic resonances , , ,
, and . In particular we show that these five
resonances can be dynamically generated from vector meson--vector meson
interaction in a coupled-channel unitary approach, which utilizes the
phenomenologically very successful hidden-gauge Lagrangians to produce the
interaction kernel between two vector mesons, which is then unitarized by the
Bethe-Salpeter-equation method. The data on the strong decay branching ratios,
total decay widths, and radiative decay widths of these five states, and on
related decay processes can all be well described by such an approach.
We also make predictions, compare them with the results of earlier studies, and
highlight observables that if measured can be used to distinguish different
pictures of these resonances.Comment: 9 pages; Invited talk at workshop CHIRAL'10, Valencia (Spain), June
21-24, 201
A systematic study of Zr and Sn isotopes in the Relativistic Mean Field theory
The ground-state properties of Zr and Sn isotopes are studied within the
relativistic mean field theory. Zr and Sn isotopes have received tremendous
attention due to various reasons, including the predicted giant halos in the
neutron-rich Zr isotopes, the unique feature of being robustly spherical in the
region of Sn Sn and the particular interest of Sn
isotopes to nuclear astrophysics. Furthermore, four (semi-) magic neutron
numbers, 40, 50, 82 and 126, make these two isotopic chains particularly
important to test the pairing correlations and the deformations in a
microscopic model. In the present work, we carry out a systematic study of Zr
and Sn isotopes from the proton drip line to the neutron drip line with
deformation effects, pairing correlations and blocking effects for nuclei with
odd number of neutrons properly treated. A constrained calculation with
quadrupole deformations is performed to find the absolute minimum for each
nucleus on the deformation surface. All ground-state properties, including the
separation energies, the odd-even staggerings, the nuclear radii, the
deformations and the single-particle spectra are analyzed and discussed in
detail.Comment: the final version to appear in Modern Physics Letters A. more
figures, discussions, and references added. the data remain unchange
Mgb2 Nonlinear Properties Investigated under Localized High RF Magnetic Field Excitation
In order to increase the accelerating gradient of Superconducting Radio
Frequency (SRF) cavities, Magnesium Diboride (MgB2) opens up hope because of
its high transition temperature and potential for low surface resistance in the
high RF field regime. However, due to the presence of the small superconducting
gap in the {\pi} band, the nonlinear response of MgB2 is potentially quite
large compared to a single gap s-wave superconductor (SC) such as Nb.
Understanding the mechanisms of nonlinearity coming from the two-band structure
of MgB2, as well as extrinsic sources, is an urgent requirement. A localized
and strong RF magnetic field, created by a magnetic write head, is integrated
into our nonlinear-Meissner-effect scanning microwave microscope [1]. MgB2
films with thickness 50 nm, fabricated by a hybrid physical-chemical vapor
deposition technique on dielectric substrates, are measured at a fixed location
and show a strongly temperature-dependent third harmonic response. We propose
that at least two mechanisms are responsible for this nonlinear response, one
of which involves vortex nucleation and penetration into the film. [1] T. M.
Tai, X. X. Xi, C. G. Zhuang, D. I. Mircea, S. M. Anlage, "Nonlinear Near-Field
Microwave Microscope for RF Defect Localization in Superconductors", IEEE
Trans. Appl. Supercond. 21, 2615 (2011).Comment: 6 pages, 6 figure
- …