97 research outputs found
Real time statistical field theory
We have written a {\it Mathematica} program that calculates the integrand
corresponding to any amplitude in the closed-time-path formulation of real time
statistical field theory. The program is designed so that it can be used by
someone with no previous experience with {\it Mathematica}. It performs the
contractions over the tensor indices that appear in real time statistical field
theory and gives the result in the 1-2, Keldysh or RA basis. We have used the
program to calculate the ward identity for the QED 3-point function, the QED
4-point function for two photons and two fermions, and the QED 5-point function
for three photons and two fermions. In real time statistical field theory,
there are seven 3-point functions, 15 4-point functions and 31 5-point
functions. We produce a table that gives the results for all of these
functions. In addition, we give a simple general expression for the KMS
conditions between -point green functions and vertex functions, in both the
Keldysh and RA basesComment: 25 pages, 12 figure
Mass Dependence of M3Y-Type Interactions and the Effects of Tensor Correlations
The mass dependence of the M3Y-type effective interactions and the effects of
tensor correlations are examined. Two-body nuclear matrix elements are obtained
by the lowest order constrained variational (LOCV) technique with and without
tensor correlations. We have found that the tensor correlations are important
especially in the triplet-even (TE) and tensor-even (TNE) channels in order to
reproduce the G-matrix elements obtained previously. Then M3Y-type potentials
for inelastic scattering are obtained by fitting our two-body matrix elements
to those of a sum of Yukawa functions for the mass numbers A=24, A=40 and A=90.Comment: 13 pages, 6 table
Systematics of proton emission
A very simple formula is presented that relates the logarithm of the
half-life, corrected by the centrifugal barrier, with the Coulomb parameter in
proton decay processes. The corresponding experimental data lie on two straight
lines which appear as a result of a sudden change in the nuclear shape marking
two regions of deformation independently of the angular momentum of the
outgoing proton. This feature provides a powerful tool to assign experimentally
quantum numbers in proton emitters.Comment: 4 pages, 3 figure
The effect of multiple deformations on the formation of ultrafine grained steels
A C-Mn-Nb-Ti steel was deformed by hot torsion to study ultrafine ferrite formation through dynamic strain-induced transformation (DSIT) in conjunction with air cooling. A systematic study was carried out first to evaluate the effect of deformation temperature and prior austenite grain size on the critical strain for ultrafine ferrite formation (ε C,UFF) through single-pass deformation. Then, multiple deformations in the nonrecrystallization region were used to study the effect of thermomechanical parameters (i.e., strain, deformation temperature, etc.) on ε C,UFF. The multiple deformations in the nonrecrystallization region significantly reduced ε C,UFF, although the total equivalent strain for a given thermomechanical condition was higher than that required in single-pass deformation. The current study on a Ni-30Fe austenitic model alloy revealed that laminar microband structures were the key intragranular defects in the austenite for nucleation of ferrite during the hot torsion test. The microbands were refined and overall misorientation angle distribution increased with a decrease in the deformation temperature for a given thermomechanical processing condition. For nonisothermal multipass deformation, there was some contribution to the formation of high-angle microband boundaries from strains at higher temperature, although the strains were not completely additive.<br /
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Observation of Single Collisionally Cooled Trapped Ions in a Buffer Gas
Whole-genome sequencing reveals host factors underlying critical COVID-19
Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease
Changes in the zymogenic cell populations of the abomasa of sheep infected with Haemonchus contortus
The effects of dietary urea supplementation and of a 10-week trickle infection regime, simulating chronic exposure to Haemonchus contortus, on the zymogenic population of the abomasa of Hampshire Down lambs was examined, dt necropsy a variety of parameters including plasma pepsinogen concentrations, the wet weights of abomasal fundic mucosal pieces and the amounts of pepsinogen contained in them, were assessed. Tissue pepsinogen concentration was measured as the total, acid-stable proteolytic activity present in mucosal homogenates, as well as immunohistochemically. The immunohistochemical findings were quantified using computer-aided image analysis. Elevation of plasma pepsinogen concentrations in infected animals was of borderline significance (P = 0.06). The fundic mucosae of infected animals were heavier (P < 0.02) than those of control animals, but there was no overall change in the pepsinogen content of tissues. Immunohistochemistry revealed that infected animals had increased numbers of zymogenic cells, due to mucous cell hyperplasia and the adaptation of cells to produce both mucins and pepsinogen. The pepsinogen content of chief cells, the major source of pepsinogen in uninfected animals, was reduced in infected lambs. Image analysis confirmed that at a mid-point of the mucosa of infected animals there was increased pepsinogen-specific immunoreactivity that corresponded with areas of mucosal hyperplasia. Mucous cell hyperplasia might therefore allow the maintenance of pepsinogen secretion in infected animals even if chief cell output is reduced.Peer reviewe
Patients with delayed gastric emptying following laparoscopic repair of large hiatus hernias regain long-term quality of life
Abstract not available.David S. Liu, Tim Bright, Sarah K. Thompson, Tanya Irvine, David I. Watson, Ahmad Al
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