Failure of the Regge approach in two dimensional quantum gravity

Regge's method for regularizing euclidean quantum gravity is applied to two dimensional gravity. We use two different strategies to simulate the Regge path integral at a fixed value of the total area: A standard Metropolis simulation combined with a histogramming method and a direct simulation using a Hybrid Monte Carlo algorithm. Using topologies with genus zero and two and a scale invariant integration measure, we show that the Regge method does not reproduce the value of the string susceptibility of the continuum model. We show that the string susceptibility depends strongly on the choice of the measure in the path integral. We argue that the failure of the Regge approach is due to spurious contributions of reparametrization degrees of freedom to the path integral.Comment: 27 pages, LaTex + uuencoded figure files (13 postscript files

The unexpected resurgence of Weyl geometry in late 20-th century physics

Weyl's original scale geometry of 1918 ("purely infinitesimal geometry") was withdrawn by its author from physical theorizing in the early 1920s. It had a comeback in the last third of the 20th century in different contexts: scalar tensor theories of gravity, foundations of gravity, foundations of quantum mechanics, elementary particle physics, and cosmology. It seems that Weyl geometry continues to offer an open research potential for the foundations of physics even after the turn to the new millennium.Comment: Completely rewritten conference paper 'Beyond Einstein', Mainz Sep 2008. Preprint ELHC (Epistemology of the LHC) 2017-02, 92 pages, 1 figur

The Evolution of Pepsinogen C Genes in Vertebrates: Duplication, Loss and Functional Diversification

<div><h3>Background</h3><p>Aspartic proteases comprise a large group of enzymes involved in peptide proteolysis. This collection includes prominent enzymes globally categorized as pepsins, which are derived from pepsinogen precursors. Pepsins are involved in gastric digestion, a hallmark of vertebrate physiology. An important member among the pepsinogens is pepsinogen C (<em>Pgc</em>). A particular aspect of <em>Pgc</em> is its apparent single copy status, which contrasts with the numerous gene copies found for example in pepsinogen A (<em>Pga</em>). Although gene sequences with similarity to <em>Pgc</em> have been described in some vertebrate groups, no exhaustive evolutionary framework has been considered so far.</p> <h3>Methodology/Principal Findings</h3><p>By combining phylogenetics and genomic analysis, we find an unexpected <em>Pgc</em> diversity in the vertebrate sub-phylum. We were able to reconstruct gene duplication timings relative to the divergence of major vertebrate clades. Before tetrapod divergence, a single <em>Pgc</em> gene tandemly expanded to produce two gene lineages (<em>Pgbc</em> and <em>Pgc2</em>). These have been differentially retained in various classes. Accordingly, we find <em>Pgc2</em> in sauropsids, amphibians and marsupials, but not in eutherian mammals. <em>Pgbc</em> was retained in amphibians, but duplicated in the ancestor of amniotes giving rise to <em>Pgb</em> and <em>Pgc1</em>. The latter was retained in mammals and probably in reptiles and marsupials but not in birds. <em>Pgb</em> was kept in all of the amniote clade with independent episodes of loss in some mammalian species. Lineage specific expansions of <em>Pgc2</em> and <em>Pgbc</em> have also occurred in marsupials and amphibians respectively. We find that teleost and tetrapod <em>Pgc</em> genes reside in distinct genomic regions hinting at a possible translocation.</p> <h3>Conclusions</h3><p>We conclude that the repertoire of <em>Pgc</em> genes is larger than previously reported, and that tandem duplications have modelled the history of <em>Pgc</em> genes. We hypothesize that gene expansion lead to functional divergence in tetrapods, coincident with the invasion of terrestrial habitats.</p> </div

An Intervention to Reduce HIV Risk Behavior of Substance-Using Men Who Have Sex with Men: A Two-Group Randomized Trial with a Nonrandomized Third Group

In a randomized trial of a behavioral intervention among substance-using men who have sex with men, aimed at reducing sexual risk behavior, Mansergh and colleagues fail to find evidence of a reduction in risk from the intervention

Activity pacing for osteoarthritis symptom management: study design and methodology of a randomized trial testing a tailored clinical approach using accelerometers for veterans and non-veterans

<p>Abstract</p> <p>Background</p> <p>Osteoarthritis (OA) is a prevalent chronic disease and a leading cause of disability in adults. For people with knee and hip OA, symptoms (e.g., pain and fatigue) can interfere with mobility and physical activity. Whereas symptom management is a cornerstone of treatment for knee and hip OA, limited evidence exists for behavioral interventions delivered by rehabilitation professionals within the context of clinical care that address how symptoms affect participation in daily activities. Activity pacing, a strategy in which people learn to preplan rest breaks to avoid symptom exacerbations, has been effective as part of multi-component interventions, but hasn't been tested as a stand-alone intervention in OA or as a tailored treatment using accelerometers. In a pilot study, we found that participants who underwent a tailored activity pacing intervention had reduced fatigue interference with daily activities. We are now conducting a full-scale trial.</p> <p>Methods/Design</p> <p>This paper provides a description of our methods and rationale for a trial that evaluates a tailored activity pacing intervention led by occupational therapists for adults with knee and hip OA. The intervention uses a wrist accelerometer worn during the baseline home monitoring period to glean recent symptom and physical activity patterns and to tailor activity pacing instruction based on how symptoms relate to physical activity. At 10 weeks and 6 months post baseline, we will examine the effectiveness of a tailored activity pacing intervention on fatigue, pain, and physical function compared to general activity pacing and usual care groups. We will also evaluate the effect of tailored activity pacing on physical activity (PA).</p> <p>Discussion</p> <p>Managing OA symptoms during daily life activity performance can be challenging to people with knee and hip OA, yet few clinical interventions address this issue. The activity pacing intervention tested in this trial is designed to help people modulate their activity levels and reduce symptom flares caused by too much or too little activity. As a result of this trial, we will be able to determine if activity pacing is more effective than usual care, and among the intervention groups, if an individually tailored approach improves fatigue and pain more than a general activity pacing approach.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01192516">NCT01192516</a></p

The role of diet in the aetiopathogenesis of inflammatory bowel disease

Crohn’s disease and ulcerative colitis, collectively known as IBD, are chronic inflammatory disorders of the gastrointestinal tract. Although the aetiopathogenesis of IBD is largely unknown, it is widely thought that diet has a crucial role in the development and progression of IBD. Indeed, epidemiological and genetic association studies have identified a number of promising dietary and genetic risk factors for IBD. These preliminary studies have led to major interest in investigating the complex interaction between diet, host genetics, the gut microbiota and immune function in the pathogenesis of IBD. In this Review, we discuss the recent epidemiological, gene–environment interaction, microbiome and animal studies that have explored the relationship between diet and the risk of IBD. In addition, we highlight the limitations of these prior studies, in part by explaining their contradictory findings, and review future directions

Photovoltaic effect by vapor-printed polyselenophene

Polyselenophene (PSe) donor layers are successfully integrated into organic photovoltaic devices (OPV) for the first time. Thin, patterned films of this insoluble semiconductor were fabricated using a vacuum-based vapor-printing technique, oxidative chemical vapor deposition (oCVD) combined with in-situ shadow masking. The vapor-printed PSe exhibits a reduced optical bandgap of 1.76 eV and enhanced photo-responsivity in the red compared to its sulfur containing analog, polythiophene. These relative advantages are most likely explained by selenium’s enhanced electron-donating character compared to sulfur. The HOMO level of PSe was determined to be at −4.85 eV. The maximum power conversion efficiency achieved was 0.4% using a bilayer heterojunction device architecture with C₆₀ as the donor.United States. Army Research Office (W911NF-13-D-0001