Tensor meson exchange at low energies

We complete the analysis of meson resonance contributions to chiral low-energy constants of O(p^4) by including all quark-antiquark bound states with orbital angular momentum less or equal to one. Different tensor meson Lagrangians used in previous work are shown to produce the same final results for the low-energy constants once QCD short-distance constraints are properly implemented. We also discuss the possible relevance of axial-vector mesons with odd C-parity.Comment: 20 pages, comparison with previous work updated, typos removed, results unchanged, version to appear in EPJ

Design and construction of the MicroBooNE detector

This paper describes the design and construction of the MicroBooNE liquid argon time projection chamber and associated systems. MicroBooNE is the first phase of the Short Baseline Neutrino program, located at Fermilab, and will utilize the capabilities of liquid argon detectors to examine a rich assortment of physics topics. In this document details of design specifications, assembly procedures, and acceptance tests are reported

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

Somatotopically inappropriate projections from thalamocortical neurons to the SI cortex of the cat demonstrated by the use of intracortical microstimulation

Single thalamocortical neurons with receptive fields on the toes were antidromically activated by the passage of 300-microseconds, 0.5- to 10-microA pulses through glass micropipette electrodes placed within somatotopically identified regions of the digit representation of the cat first somatosensory (SI) cortex. The somatotopy of the cortex was determined using recordings from single cortical neurons (see "Methods"), and the positions of the all tracks were marked on an enlarged photograph of the postcruciate cortex. In two of the three protocols, a very precise map of the boundary between two adjacent toes was produced prior to attempting intracortical microstimulation. Slopes of the threshold-distance curves at the sites of the lowest recorded thresholds were on the order of 0.8 microA/10 micron. This value, together with information on the anatomy of the cortical arborizations of thalamocortical neurons (Landry and Deschenes, 1981), suggested that currents of 2 and 5 microA would not activate the cortical processes of thalamocortical neurons at distances greater than 50 and 90 microns, respectively. With currents below 5 microA, thalamocortical neurons could be antidromically activated at a number of sites at depths between 340 and 930 microns (layer IV and upper layer III) and between 1,050 and 1,460 microns (layer VI). A total of 13 thalamocortical neurons could be antidromically activated using current pulses of between 0.8 and 5.0 microA, from within tracks at tangential distances of 250-830 microns from the nearest track through the somatotopically appropriate region. Within somatotopically inappropriate regions, cortical neurons frequently had receptive fields on a toe adjacent to that bearing the receptive field of the thalamic neuron(s) under study. The possible relationship of somatotopically inappropriate projections to the reorganization of cortical somatotopy following digit amputation, paw amputation, and nerve section is discussed

An x-ray microprobe beam line for trace element analysis

The application of synchrotron radiation to an x-ray microprobe for trace element analysis is a complementary and natural extension of existing microprobe techniques using electrons, protons, and heavier ions as excitation sources for x-ray fluorescence. The ability to focus charged particles leads to electron microprobes with spatial resolutions in the sub-micrometer range and down to 100 ppM detection limits and proton microprobes with micrometer resolution and ppM detection limits. The characteristics of synchrotron radiation that prove useful for microprobe analysis include a broad and continuous energy spectrum, a relatively small amount of radiation damage compared to that deposited by charged particles, a highly polarized source which reduces background scattered radiation in an appropriate counting geometry, and a small vertical divergence angle of approx.0.2 mrad which allows for focussing of the light beam into a small spot with high flux. The features of a dedicated x-ray microprobe beam line developed at the National Synchrotron Light Source (NSLS) are described. 4 refs., 3 figs