Energy Relaxation In Collisions Of Hydrogen And Deuterium With Oxygen Atoms

Collision energy transfer processes between hydrogen, deuterium, and oxygen atoms in the upper atmospheres of the terrestrial planets are studied. A new set of interaction potentials has been constructed using an accurate ab initio method. Full orientation-dependent scattering cross sections have been obtained quantum mechanically and have been incorporated into the construction of the linear Boltzmann kinetic equation describing the energy relaxation process. The isotope and temperature dependence of the energy relaxation parameters have been analyzed. Distributions of the secondary energetic recoil atoms have been computed and the fractions of hot atoms capable of escaping from the atmospheres of the terrestrial planets have been determined. For applications to atmospheric physics and astrophysics, we have computed effective hard sphere cross sections for O + H and O + D collisions that closely reproduce the energy relaxation kinetics obtained from the linear Boltzmann equation. These effective cross sections, which are functions of the laboratory frame collisional energy and the temperature of the bath gas, may be used in simulations of the thermalization of hot O, H, and D atoms and their escape from planets.Astronom

Unity through Diversity: Value-in-Diversity Beliefs, Work Group Diversity, and Group Identification

Research on work group diversity has more or less neglected the possibility that reactions to diversity may be informed by individuals' beliefs about the value of diversity (vs. homogeneity) for their work group. We studied the role of such diversity beliefs as a moderator of the relationship between work group diversity and individuals' identification with the work group across two studies. Study 1 was a cross-sectional survey that focused on gender diversity and gender diversity beliefs. Study 2 was a laboratory experiment in which work group diversity and diversity beliefs were manipulated. Results of both studies support the prediction that work group diversity and group identification are more positively related the more individuals believe in the value of diversit

Disks and Jets : Gravity, Rotation and Magnetic Fields

Magnetic fields are fundamental to the dynamics of both accretion disks and the jets that they often drive. We review the basic physics of these phenomena, the past and current efforts to model them numerically with an emphasis on the jet-disk connection, and the observational constraints on the role of magnetic fields in the jets of active galaxies on all scalesPeer reviewe

Narrow Stimulated Resonance Raman Scattering and WGM Lasing in Small Conjugated Polymer Particles for Live Cell Tagging and Tracking

Conjugated polymer particles are brightly fluorescing and stable materials for live cell imaging. Combination of conjugated polymers with a whispering gallery mode (WGM) resonator allows laser emission from microscale particles. Once internalized by cells, the mode pattern of the laser emission can be used for tagging and tracking, as each laser spectrum represents a bar code to identify individual cells. However, currently these particle systems are limited by their large size, which might interfere with cellular functions. Here, stimulated resonance Raman scattering (SRRS) in small conjugated polymer microparticles is presented as a new method for generating narrow emission as an alternative to WGM-based laser emission. This opens up spectral range for multiplexing optical readout and multicolor imaging of live cells. The synthesis of monodisperse micrometer-sized poly(fluorene-co-divinylbenzene) particles is discussed and their WGM and SRRS emission are characterized. Finally, how these particles and their emission can be employed in live cell imaging and tagging is showcased. © 2020 The Authors. Advanced Optical Materials published by Wiley-VCH Gmb

Lowering the cutoff value for increment increases the sensitivity for the diagnosis of Lambert-Eaton myasthenic syndrome

Background: Increment of compound muscle action potential amplitude is a diagnostic hallmark of Lambert-Eaton myasthenic syndrome (LEMS). Making a diagnosis can be challenging, therefore, a proper cutoff for abnormal increment is highly relevant for improved recognition

Global well-posedness of the KP-I initial-value problem in the energy space

We prove that the KP-I initial value problem is globally well-posed in the natural energy space of the equation

Soluble receptor for advanced glycation end products as an indicator of pulmonary vascular injury after cardiac surgery

Background: Cardiac surgery is frequently complicated by an acute vascular lung injury and this may be mediated, at least in part, by the (soluble) receptor for advanced glycation end products (sRAGE).Methods: In two university hospital intensive care units, circulating sRAGE was measured together with the 68Gallium-transferrin pulmonary leak index (PLI), a measure of pulmonary vascular permeabiliy, in 60 consecutive cardiac surgery patients stratified by the amount of blood transfusion, within 3 hours of admission to the intensive care.Results: Cardiac surgery resulted in elevated plasma sRAGE levels compared to baseline (315 ± 181 vs 110 ± 55 pg/ml, P = 0.001). In 37 patients the PLI was elevated 50% above normal. The PLI correlated with sRAGE (r2 = 0.11, P = 0.018). Plasma sRAGE discriminated well between those with an elevated PLI and those with a normal PLI (area under the operator curve 0.75; P = 0.035; 95% CI 0.55-0.95), with 91% sensitivity but low specificity of 36% at a cutoff value of 200 pg/mL

A critical role for cystathionine-β-synthase in hydrogen sulfide-mediated hypoxic relaxation of the coronary artery

Hypoxia-induced coronary artery vasodilatation protects the heart by increasing blood flow under ischemic conditions, however its mechanism is not fully elucidated. Hydrogen sulfide (H2S) is reported to be an oxygen sensor/transducer in the vasculature. The present study aimed to identify and characterise the role of H2S in the hypoxic response of the coronary artery, and to define the H2S synthetic enzymes involved. Immunoblotting and immunohistochemistry showed expression of all three H2S-producing enzymes, cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (MPST), in porcine coronary artery. Artery segments were mounted for isometric tension recording; hypoxia caused a transient endothelium-dependent contraction followed by prolonged endothelium-independent relaxation. The CBS inhibitor amino-oxyacetate (AOAA) reduced both phases of the hypoxic response. The CSE inhibitor dl-propargylglycine (PPG) and aspartate (limits MPST) had no effect alone, but when applied together with AOAA the hypoxic relaxation response was further reduced. Exogenous H2S (Na2S and NaHS) produced concentration-dependent contraction followed by prolonged relaxation. Responses to both hypoxia and exogenous H2S were dependent on the endothelium, NO, cGMP, K+ channels and Cl−/HCO3 − exchange. H2S production in coronary arteries was blocked by CBS inhibition (AOAA), but not by CSE inhibition (PPG). These data show that H2S is an endogenous mediator of the hypoxic response in coronary arteries. Of the three H2S-producing enzymes, CBS, expressed in the vascular smooth muscle, appears to be the most important for H2S generated during hypoxic relaxation of the coronary artery. A contribution from other H2S-producing enzymes only becomes apparent when CBS activity is inhibited

Interaction between toothbrushes and toothpaste abrasive particles in simulated tooth cleaning

There are currently many toothbrush designs on the market incorporating different filament configurations such as filaments at various angles and different lengths and made from several different materials. In order to understand how the tooth cleaning process occurs there is a need to investigate in detail how the abrasive particles in a toothpaste interact with the filaments in a teeth cleaning contact and cause material removal from a plaque or stain layer. The following describes the development of optical apparatus to enable the visualisation of simulated teeth cleaning contacts. Studies have been carried out using the apparatus to investigate particle entrainment into the contact and how it differs with varying bristle configurations. The effects of filament stiffness and tip shape were also investigated. Various types of electric toothbrushes were also tested. The studies have shown how particles are trapped at the tips of toothbrush filaments. Particles, suspended in fluid, approach the filament tips, as they pass through they may become trapped. Greater particle entrainment into the filament tip contact occurs with a reciprocating action at low filament loads and deflections than with a sliding motion. Large particles are less likely to enter tip contacts and are trapped between tips or under the filament bend at higher loads. Whether the particles are likely to be trapped and how long they remain so depends on the filament stiffness and degree of splay on loading and the filament configuration. The direction the filaments point in, the number of filaments in a tuft, the spacing of the tufts and the way the filaments splay when deflected all have an influence on entrainment of particles. Tufts with tightly packed stiff filaments which deflected together on loading were more effective at trapping particles than more flexible filaments that splayed out on loading as they present more of a barrier to particle entry and exit from the tip region