Non-invasive assessment of kidney oxygenation: a role for BOLD MRI

Blood oxygen level-dependent (BOLD) contrast magnetic resonance imaging (MRI) has been applied to investigate kidney oxygenation in human patients. These investigations reflect the progress of radiology from a primarily anatomic discipline to one that provides insight into tissue physiology. In particular, magnetic resonance imaging (MRI) is non-invasive, uses no ionizing radiation, and provides insight into disease development and tissue physiology

Rat cerebral cortical synaptoneurosomal membranes. Structure and interactions with imidazobenzodiazepine and 1,4-dihydropyridine calcium channel drugs

Small angle x-ray scattering has been used to investigate the structure of synaptoneurosomal (SNM) membranes from rat cerebral cortex. Electron micrographs of the preparation showed SNM with classical synaptic appositions intact, other vesicles, occasional mitochondria, and some myelin. An immunoassay for myelin basic protein placed the myelin content of normal rat SNM at less than 2% by weight of the total membrane present. X-Ray diffraction patterns showed five diffraction orders with a unit cell repeat for the membrane of 71 to 78 A at higher hydration states. At lower hydration, 11 orders appeared; the unit cell repeat was 130 A, indicating that the unit cell contained two membranes. Electron density profiles for the 130-A unit cell were determined; they clearly showed the two opposed asymmetrical membranes of the SNM vesicles. SNM membrane/buffer partition coefficients (Kp) of imidazobenzodiazepine and 1,4-dihydropyridine (DHP) calcium channel drugs were measured; Kp's for DHP drugs were approximately five times higher in rabbit light sarcoplasmic reticulum than in SNM. Ro 15–1788 and the DHP BAY K 8644 bind primarily to the outer monolayer of vesicles of intact SNM membranes. Nonspecific equilibrium binding of Ro 15–1788 occurs mainly in the upper acyl chain of the bilayer in lipid extracts of SNM membrane

Supersymmetric Gauge Theories in Twistor Space

We construct a twistor space action for N=4 super Yang-Mills theory and show that it is equivalent to its four dimensional spacetime counterpart at the level of perturbation theory. We compare our partition function to the original twistor-string proposal, showing that although our theory is closely related to string theory, it is free from conformal supergravity. We also provide twistor actions for gauge theories with N<4 supersymmetry, and show how matter multiplets may be coupled to the gauge sector.Comment: 23 pages, no figure

Capability, opportunity, and motivation to enact hygienic practices in the early stages of the COVID‐19 outbreak in the United Kingdom

Objectives The COVID‐19 pandemic is one of the greatest global health threats facing humanity in recent memory. This study aimed to explore influences on hygienic practices, a set of key transmission behaviours, in relation to the Capability, Opportunity, Motivation‐Behaviour (COM‐B) model of behaviour change (Michie et al., 2011). Design Data from the first wave of a longitudinal survey study were used, launched in the early stages of the UK COVID‐19 pandemic. Methods Participants were 2025 adults aged 18 and older, representative of the UK population, recruited by a survey company from a panel of research participants. Participants self‐reported motivation, capability, and opportunity to enact hygienic practices during the COVID‐19 outbreak. Results Using regression models, we found that all three COM‐B components significantly predicted good hygienic practices, with motivation having the greatest influence on behaviour. Breaking this down further, the subscales psychological capability, social opportunity, and reflective motivation positively influenced behaviour. Reflective motivation was largely driving behaviour, with those highest in reflective motivation scoring 51% more on the measure of hygienic practices compared with those with the lowest scores. Conclusions Our findings have clear implications for the design of behaviour change interventions to promote hygienic practices. Interventions should focus on increasing and maintaining motivation to act and include elements that promote and maintain social support and knowledge of COVID‐19 transmission. Groups in particular need of targeting for interventions to increase hygienic practices are males and those living in cities and suburbs

Aspects of the dynamics of colloidal suspensions: Further results of the mode-coupling theory of structural relaxation

Results of the idealized mode-coupling theory for the structural relaxation in suspensions of hard-sphere colloidal particles are presented and discussed with regard to recent light scattering experiments. The structural relaxation becomes non-diffusive for long times, contrary to the expectation based on the de Gennes narrowing concept. A semi-quantitative connection of the wave vector dependences of the relaxation times and amplitudes of the final $\alpha$-relaxation explains the approximate scaling observed by Segr{\`e} and Pusey [Phys. Rev. Lett. {\bf 77}, 771 (1996)]. Asymptotic expansions lead to a qualitative understanding of density dependences in generalized Stokes-Einstein relations. This relation is also generalized to non-zero frequencies thereby yielding support for a reasoning by Mason and Weitz [Phys. Rev. Lett {\bf 74}, 1250 (1995)]. The dynamics transient to the structural relaxation is discussed with models incorporating short-time diffusion and hydrodynamic interactions for short times.Comment: 11 pages, 9 figures; to be published in Phys. Rev.

Low-temperature dynamical simulation of spin-boson systems

The dynamics of spin-boson systems at very low temperatures has been studied using a real-time path-integral simulation technique which combines a stochastic Monte Carlo sampling over the quantum fluctuations with an exact treatment of the quasiclassical degrees of freedoms. To a large degree, this special technique circumvents the dynamical sign problem and allows the dynamics to be studied directly up to long real times in a numerically exact manner. This method has been applied to two important problems: (1) crossover from nonadiabatic to adiabatic behavior in electron transfer reactions, (2) the zero-temperature dynamics in the antiferromagnetic Kondo region 1/2<K<1 where K is Kondo's parameter.Comment: Phys. Rev. B (in press), 28 pages, 6 figure

A network approach to understanding social distancing behaviour during the first UK lockdown of the COVID-19 pandemic

Objective Given the highly infectious nature of COVID-19, social distancing practices are key in stemming the spread of the virus. We aimed to assess the complex interplay among psychological factors, socio-demographic characteristics and social distancing behaviours within the framework of the widely used Capability, Opportunity, Motivation-Behaviour (COM-B) model. Design The present research employed network psychometrics on data collected during the first UK lockdown in April 2020 as part of the COVID-19 Psychological Research Consortium (C19PRC) Study. Using a network approach, we examined the predictions of psychological and demographic variables onto social distancing practices at two levels of analysis: macro and micro. Design The present research employed network psychometrics on data collected during the first UK lockdown in April 2020 as part of the COVID-19 Psychological Research Consortium (C19PRC) Study. Using a network approach, we examined the predictions of psychological and demographic variables onto social distancing practices at two levels of analysis: macro and micro. Results Our findings revealed several factors that influenced social distancing behaviour during the first UK lockdown. The COM-B model was successful in predicting particular aspects of social-distancing via the influence of psychological capability and motivation at the macro-and micro-levels, respectively. Notably, demographic variables, such as education, income, and age, were directly and uniquely predictive of certain social distancing behaviours. Conclusion Our findings reveal psychological factors that are key predictors of social distancing behaviour and also illustrate how demographic variables directly influence such behaviour. Our research has implications for the design of empirically-driven interventions to promote adherence to social distancing practices in this and future pandemics

An 18‐month follow‐up of the Covid‐19 psychology research consortium study panel: survey design and fieldwork procedures for Wave 6

Objectives Established in March 2020, the C19PRC Study monitors the psychological and socio-economic impact of the pandemic in the UK and other countries. This paper describes the protocol for Wave 6 (August–September 2021). Methods The survey assessed: COVID-19 related experiences; experiences of common mental health disorders; psychological characteristics; and social and political attitudes. Adult participants from any previous wave (N = 3170) were re-invited, and sample replenishment procedures helped manage attrition. Weights were calculated using a survey raking algorithm to ensure the on-going original panel (from baseline) was nationally representative in terms of gender, age, and household income, amongst other factors. Results 1643 adults were re-interviewed at Wave 6 (51.8% retention rate). Non-participation was higher younger adults, those born outside UK, and adults living in cities. Of the adults recruited at baseline, 54.3% (N = 1100) participated in Wave 6. New respondent (N = 415) entered the panel at this wave, resulting in cross-sectional sample for Wave 6 of 2058 adults. The raking procedure re-balanced the longitudinal panel to within 1.3% of population estimates for selected socio-demographic characteristics. Conclusions This paper outlines the growing strength of the publicly available C19PRC Study data for COVID-19-related interdisciplinary research