54 research outputs found
Isotopic Production Cross Sections in Proton-Nucleus Collisions at 200 MeV
Intermediate mass fragments (IMF) from the interaction of Al,
Co and Au with 200 MeV protons were measured in an angular range
from 20 degree to 120 degree in the laboratory system. The fragments, ranging
from isotopes of helium up to isotopes of carbon, were isotopically resolved.
Double differential cross sections, energy differential cross sections and
total cross sections were extracted.Comment: accepted by Phys. Rev.
Chiral Symmetry and the Nucleon Structure Functions
The isospin asymmetry of the sea quark distribution as well as the
unexpectedly small quark spin fraction of the nucleon are two outstanding
discoveries recently made in the physics of deep-inelastic structure functions.
We evaluate here the corresponding quark distribution functions within the
framework of the chiral quark soliton model, which is an effective quark model
of baryons maximally incorporating the most important feature of low energy
QCD, i.e. the chiral symmetry and its spontaneous breakdown. It is shown that
the model can explain qualitative features of the above-mentioned nucleon
structure functions within a single framework, thereby disclosing the
importance of chiral symmetry in the physics of high energy deep-inelastic
scatterings.Comment: 20pages, LaTex, 5 Postscript figures A numerical error of the
original version was corrected. The discussion on the regularization
dependence of distribution functions has been added. A comparison with the
low energy-scale parametrization of Gloeck, Reya and Vogt has been mad
National surveillance for hemophilia inhibitors in the United States: Summary report of an expert meeting: National Inhibitor Surveillance in the U.S.
On March 12, 2012, the Centers for Disease Control and Prevention (CDC) held a meeting of its partners in hemophilia treatment, community-based organizations, industry, and government to review data and discuss implementation issues relevant to planned United States (U.S.) national inhibitor surveillance. Issues discussed included the current status of inhibitor surveillance in the United Kingdom (UK) and the US, the results of a US inhibitor surveillance feasibility study, proposed national surveillance schemes, laboratory testing and reporting issues and potential opportunities for future inhibitor-related research. It was concluded that implementation of a national program of inhibitor surveillance using standardized testing through an established public health registry along with patient and care provider education and targeted research provide the best opportunity to inform efforts to develop and evaluate effective prevention strategies
The Crystal Ball Data Acquisition System
The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A "physics pipeline" allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented
Measurement of the polarization parameter in backward elastic scattering at 6 GeV/c
The polarization parameter in pi /sup -/p elastic scattering has been measured in the backward angular region at an incident momentum of 6 GeV/c. The measurements cover the range of four momentum transfer u=0 to -1(GeV/c)/sup 2/, and were obtained with a high intensity pion beam, a butanol polarized proton target, and arrays of scintillation counter hodoscopes. The polarization is different from zero, in contradiction to the prediction of the naive one trajectory Regge- exchange model. It increases positively with the four-momentum transfer u, reaching a maximum of about 0.4 at u approximately=-0.3(Ge V/c)/sup 2/. It then decreases and becomes slightly negative beyond u approximately=-0.5(GeV/c)/sup 2/. A variety of baryon exchange models are briefly reviewed and none are found to be in complete agreement with all the experimental data
Chiral Symmetry and the Nucleon Spin Structure Functions
We carry out a systematic investigation of twist-two spin dependent structure
functions of the nucleon within the framework of the chiral quark soliton model
(CQSM) by paying special attention to the role of chiral symmetry of QCD. The
importance of chiral symmetry is illustrated through the good reproduction of
the recent SLAC data for the neutron spin structure function .
We also observe substantial difference between the predictions of the
longitudinally polarized distribution functions and those of the transversity
distribution functions. That the chiral symmetry may be responsible for this
difference is seen in the isospin dependence of the corresponding first
moments, i.e. the axial and tensor charges. The CQSM predicts for the ratio of the isoscalar to isovector axial
charges, while for the ratio of the
isoscalar to isovector tensor charges, which should be compared with the
prediction of the
constituent quark model or of the naive MIT bag model without proper account of
chiral symmetry. Another prominent prediction of the CQSM is the opposite
polarization of the and antiquarks, thereby indicating the
SU(2) asymmetric sea quark (spin) polarization in the nucleon.Comment: 46pages, LaTeX, 16 Postscript figure
Distinct tissue niches direct lung immunopathology via CCL18 and CCL21 in severe COVID-19
Prolonged lung pathology has been associated with COVID-19, yet the cellular and molecular mechanisms behind this chronic inflammatory disease are poorly understood. In this study, we combine advanced imaging and spatial transcriptomics to shed light on the local immune response in severe COVID-19. We show that activated adventitial niches are crucial microenvironments contributing to the orchestration of prolonged lung immunopathology. Up-regulation of the chemokines CCL21 and CCL18 associates to endothelial-to-mesenchymal transition and tissue fibrosis within these niches. CCL21 over-expression additionally links to the local accumulation of T cells expressing the cognate receptor CCR7. These T cells are imprinted with an exhausted phenotype and form lymphoid aggregates that can organize in ectopic lymphoid structures. Our work proposes immune-stromal interaction mechanisms promoting a self-sustained and non-resolving local immune response that extends beyond active viral infection and perpetuates tissue remodeling
Search for hyperdeformation in U isotopes
The U-232 nucleus was studied in order to search for a hyperdeformed band built upon the third minimum of the fission barrier. Upper limits for the percentage population of a hypothetical hyperdeformed band relative to the ground state band are given
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