Generalized Quantum Theory of Recollapsing Homogeneous Cosmologies

A sum-over-histories generalized quantum theory is developed for homogeneous minisuperspace type A Bianchi cosmological models, focussing on the particular example of the classically recollapsing Bianchi IX universe. The decoherence functional for such universes is exhibited. We show how the probabilities of decoherent sets of alternative, coarse-grained histories of these model universes can be calculated. We consider in particular the probabilities for classical evolution defined by a suitable coarse-graining. For a restricted class of initial conditions and coarse grainings we exhibit the approximate decoherence of alternative histories in which the universe behaves classically and those in which it does not. For these situations we show that the probability is near unity for the universe to recontract classically if it expands classically. We also determine the relative probabilities of quasi-classical trajectories for initial states of WKB form, recovering for such states a precise form of the familiar heuristic "J d\Sigma" rule of quantum cosmology, as well as a generalization of this rule to generic initial states.Comment: 41 pages, 4 eps figures, revtex 4. Modest revisions throughout. Physics unchanged. To appear in Phys. Rev.

The Role of Radioactivities in Astrophysics

I present both a history of radioactivity in astrophysics and an introduction to the major applications of radioactive abundances to astronomy

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

Surface water temperature observations of large lakes by optimal estimation

Optimal estimation (OE) and probabilistic cloud screening were developed to provide lake surface water temperature (LSWT) estimates from the series of (advanced) along-track scanning radiometers (ATSRs). Variations in physical properties such as elevation, salinity, and atmospheric conditions are accounted for through the forward modelling of observed radiances. Therefore, the OE retrieval scheme developed is generic (i.e., applicable to all lakes). LSWTs were obtained for 258 of Earth's largest lakes from ATSR-2 and AATSR imagery from 1995 to 2009. Comparison to in situ observations from several lakes yields satellite in situ differences of −0.2 ± 0.7 K for daytime and −0.1 ± 0.5 K for nighttime observations (mean ± standard deviation). This compares with −0.05 ± 0.8 K for daytime and −0.1 ± 0.9 K for nighttime observations for previous methods based on operational sea surface temperature algorithms. The new approach also increases coverage (reducing misclassification of clear sky as cloud) and exhibits greater consistency between retrievals using different channel–view combinations. Empirical orthogonal function (EOF) techniques were applied to the LSWT retrievals (which contain gaps due to cloud cover) to reconstruct spatially and temporally complete time series of LSWT. The new LSWT observations and the EOF-based reconstructions offer benefits to numerical weather prediction, lake model validation, and improve our knowledge of the climatology of lakes globally. Both observations and reconstructions are publically available from http://hdl.handle.net/10283/88

Expert Failure: Re-evaluating Research Assessment

EDITORIAL © 2013 Eisen et al. Funding organisations, scientists, and the general public need robust and reliable ways to evaluate the output of scientific research. In this issue of PLOS Biology, Adam Eyre-Walker and Nina Stoletzki analyse the subjective assessment and citations of more than 6,000 published papers [1]. They show that expert assessors are biased by the impact factor (IF) of the journal in which the paper has been published and cannot consistently and independently judge the “merit” of a paper or predict its future impact, as measured by citations. They also show that citations themselves are not a reliable way to assess merit as they are inherently highly stochastic. In a final twist, the authors argue that the IF is probably the least-bad metric amongst the small set that they analyse, concluding that it is the best surrogate of the merit of individual papers currently available

Effects of time of year and reproductive state on the proliferation and keratinisation of bovine hoof cells

Cell proliferation and protein synthesis (keratinisation) were measured in vitro in hoof biopsy samples taken from two groups of seven heifers, the first calving in the winter and the second in the summer. Both parameters were significantly higher in summer than in winter irrespective of the heifers' reproductive state. The mean (se) measure of the rate of protein synthesis was 199 (27) dpm/microg DNA/hour in summer and 4 (1) dpm/microg DNA/hour in winter, and the equivalent values for cell proliferation (measured as DNA synthesis) were 375 (56) dpm/microg DNA/hour and 17 (4) dpm/microg DNA/hour. Changes around parturition depended on the time of the year. In the winter-calving heifers, the rates of proliferation and keratinisation increased significantly after calving from 22.3 (7.2) to 70.4 (16.6) and from 2.1 (0.7) to 12.4 (2.8) dpm/microg DNA/hour, respectively. In the summer-calving heifers, proliferation decreased from 388.2 (91.0) to 66.7 (9.6) dpm/microg DNA/hour but the rate of keratinisation did not change. Lesion scores and locomotion scores deteriorated after parturition, especially in the winter-calving group. The hooves were harder in summer than winter but their hardness was not affected by the heifers' reproductive state

Insight on polymer electrolytes for electrochemical devices applications

Polymer electrolytes (PEs) are of much attention as potential electrolytes of great technological relevance for solid-state electrochemistry, in particular for their possible practical application in devices such as batteries, supercapacitors, fuel cells, smart windows, sensors, and solar cells, among others. Generically, solid polymer electrolytes (SPEs) are mixtures of salts with basic polymers, such as poly(ethylene oxide) (PEO) or poly(ethylene imine) (PEI). However, there are also other polymers used as matrices for ionic conduction, like poly(vinyl alcohol) (PVA), poly(vinylidene fluoride) (PVDF), or natural macromolecules. A brief description of theoretical aspects of different PEs and past and recent trends in development of these materials are presented in this chapter. SPEs have many advantages including high energy density, no risk of leakage, no deleterious issues related to the presence of solvent, wide electrochemical stability window, simplified processability, and light weight. Some examples of prototypes of electrochromic device (ECD), batteries, supercapacitors, fuel cells, sensors, dye sensitized solar cells (DSSCs), and light emitting electrochemical cells are also presented and discussed in scope of this contribution.- (undefined

Selection of variables in exploratory factor analysis: An empirical comparison of a stepwise and traditional approach

Stepwise variable selection, exploratory factor analysis, goodness-of-fit, varimax rotation, statistical bias, selection accuracy, pattern accuracy,