745 research outputs found

    On a conjecture of Král concerning the subharmonic extension of continuously differentiable functions

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    summary:This note verifies a conjecture of Král, that a continuously differentiable function, which is subharmonic outside its critical set, is subharmonic everywhere

    Predicting the number of COVID-19 cases from the reported number of deaths

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    The new corona virus disease 2019 (COVID-2019) is rapidly spreading through the world. With insufficient testing, available case data may underestimate the total number of infections. We statistically estimated the cumulative number of cases with confidence intervals from the reported number of deaths, assuming that the number of infections grow exponentially with a constant doubling time. Our findings indicate that the number of unreported infections is likely at least one order of magnitude higher than the reported cases, in particular in the United States and the United Kingdom. This finding is supported by a recent mass screening for SARS-CoV-2 in Iceland which found that the actual case numbers may be about 20 times higher than the officially reported number

    On a modified-Lorentz-transformation based gravity model confirming basic GRT experiments

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    Implementing Poincar\'e's `geometric conventionalism' a scalar Lorentz-covariant gravity model is obtained based on gravitationally modified Lorentz transformations (or GMLT). The modification essentially consists of an appropriate space-time and momentum-energy scaling ("normalization") relative to a nondynamical flat background geometry according to an isotropic, nonsingular gravitational `affecting' function Phi(r). Elimination of the gravitationally `unaffected' S_0 perspective by local composition of space-time GMLT recovers the local Minkowskian metric and thus preserves the invariance of the locally observed velocity of light. The associated energy-momentum GMLT provides a covariant Hamiltonian description for test particles and photons which, in a static gravitational field configuration, endorses the four `basic' experiments for testing General Relativity Theory: gravitational i) deflection of light, ii) precession of perihelia, iii) delay of radar echo, iv) shift of spectral lines. The model recovers the Lagrangian of the Lorentz-Poincar\'e gravity model by Torgny Sj\"odin and integrates elements of the precursor gravitational theories, with spatially Variable Speed of Light (VSL) by Einstein and Abraham, and gravitationally variable mass by Nordstr\"om.Comment: v1: 14 pages, extended version of conf. paper PIRT VIII, London, 2002. v2: section added on effective tensorial rank, references added, appendix added, WEP issue deleted, abstract and other parts rewritten, same results (to appear in Found. Phys.

    Is reducing appetite beneficial for body weight management in the context of overweight and obesity? A systematic review and meta‐analysis from clinical trials assessing body weight management after exposure to satiety enhancing and/or hunger reducing products

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    This review aims to investigate whether interventions that enhance satiety and/or reduce hunger lead to beneficial effects on body weight management in the context of overweight and obesity. A comprehensive review protocol was prepared before conducting a systematic search in PubMed identifying 517 papers with 12 meeting the inclusion criteria. A thorough risk of bias assessment was performed based on the Cochrane collaboration's tool for assessing risk of bias. Based on a meta‐analysis, the average of 75 subjects exposed to satiety enhancing and/or hunger reducing foods during more than 8 weeks coincidently reduced their body weight by 3.60 (1.05; 6.15) kg (mean (95% confidence interval)) more compared with controls. Two studies analysed whether individual reductions in appetite were associated with body weight. Decreased ad libitum energy intake after exposure to the satiety enhancing and/or hunger reducing interventions explained 58% (P < 0.001) and 23% (P < 0.001) of the variations in the subsequent weight losses over 12 and 8 weeks, respectively. Robust acute effects on appetite were found equally likely to be linked to improved body weight management as sustained effects. Satiety enhancing and/or hunger reducing interventions are supported to improve body weight management, but studies specifically designed to demonstrate a causal link remain needed

    Cigarette ignition propensity, smoking behavior, and toxicant exposure: A natural experiment in Canada

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    <p>Abstract</p> <p>Background</p> <p>This study used a 'pre-post' research design to measure the impact of the Canadian reduced ignition propensity law on cigarette toxicity and smoking behavior among Canadian smokers.</p> <p>Method</p> <p>The study was conducted in Ontario, Canada over a ten-month period in 2005-2006, consisting of 4 laboratory visits (baseline N = 61, final N = 42). At Visit 1, questionnaire data and biospecimens were collected. During the following 24 hours, participants smoked 5 cigarettes <it>ad libitum </it>through a topography recording device and collected their cigarette butts. Visit 2 consisted of a questionnaire and smoking one cigarette to measure laboratory topography values. After ten months, these procedures were repeated.</p> <p>Results</p> <p>Generalized estimating equations, with law status (pre and post) as a fixed within-subject factor, were used to determine changes in behavior and biomarker exposure. Overall, there were no significant differences in smoking topography, breath carbon monoxide, and saliva cotinine pre-post law (<it>p</it>>0.1). However, analyses revealed a significant increase in the summed concentrations of hydroxyfluorene metabolites (N = 3),, and 1-hydroxypyrene in urine, with at notable increase in hydroxyphenanthrene metabolites (N = 3) (<it>p</it><sub>Σhydroxyfluorene </sub>= 0.013, 22% increase; <it>p<sub>1-hydroxypyrene </sub></it>= 0.018, 24% increase; <it>p</it><sub>Σhydroxyphenanthrene </sub>= 0.061, 17% increase).</p> <p>Conclusion</p> <p>While the results suggest no change in topography variables, data showed increases in exposure to three PAH biomarkers following reduced ignition propensity implementation in Canada. These findings suggest that human studies should be considered to evaluate policy impacts.</p

    A Method for Estimating the Number of Infections From the Reported Number of Deaths

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    At the outset of an epidemic, available case data typically underestimate the total number of infections due to insufficient testing, potentially hampering public responses. Here, we present a method for statistically estimating the true number of cases with confidence intervals from the reported number of deaths and estimates of the infection fatality ratio; assuming that the time from infection to death follows a known distribution. While the method is applicable to any epidemic with a significant mortality rate, we exemplify the method by applying it to COVID-19. Our findings indicate that the number of unreported COVID-19 infections in March 2020 was likely to be at least one order of magnitude higher than the reported cases, with the degree of underestimation among the countries considered being particularly high in the United Kingdom

    Body Burdens of Polybrominated Diphenyl Ethers among Urban Anglers

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    Polybrominated diphenyl ethers (PBDEs) have been widely used in the United States and worldwide as flame retardants. Recent PBDE production figures show that worldwide use has increased. To determine whether fish consumption is a source of PBDE exposure for humans, a cross-sectional epidemiologic study of New York and New Jersey urban anglers was conducted during the summers of 2001–2003. Frequency of local fish consumption was assessed by questionnaire, and blood samples for PBDE analysis were collected from 94 anglers fishing from piers on the lower Hudson River and Newark Bay. We analyzed PBDEs by gas chromatography–isotope dilution–high-resolution mass spectrometry. The congeners found in anglers’ serum at the highest concentrations were, by International Union of Pure and Applied Chemistry numbers, BDE-47, BDE-153, and BDE-99. Anglers reporting consumption of local fish had higher, but nonstatistically significantly different, concentrations of PBDEs than did anglers who did not eat local fish. For some congeners (BDE-100 and BDE-153), we observed moderate dose–response relationships between serum PBDE levels and frequency of reported fish intake. These findings suggest that consumption of locally caught fish is not a major route of human exposure for this study population

    Time on a Rotating Platform

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    Traditional clock synchronisation on a rotating platform is shown to be incompatible with the experimentally established transformation of time. The latter transformation leads directly to solve this problem through noninvariant one-way speed of light. The conventionality of some features of relativity theory allows full compatibility with existing experimental evidence.Comment: 12 pages, Latex, no figure. Copies available at [email protected] accepted for publication in Found. Phys. Let

    Differential patterns of lysosomal dysfunction are seen in the clinicopathological forms of primary progressive aphasia

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    Increasing evidence implicates endo-lysosomal dysfunction in frontotemporal dementia (FTD). 18 proteins were quantified using a mass spectrometry assay panel in the cerebrospinal fluid of 36 people with the language variant of FTD, primary progressive aphasia (PPA) (including 13 with non-fluent variant (nfvPPA), 11 with semantic variant (svPPA), and 12 with logopenic variant (lvPPA)) and 19 healthy controls. The concentrations of the cathepsins (B, D, F, L1, and Z) as well as AP-2 complex subunit beta, ganglioside GM2 activator, beta-hexosaminidase subunit beta, tissue alpha L-fucosidase, and ubiquitin were decreased in nfvPPA compared with controls. In contrast, the concentrations of amyloid beta A4 protein, cathepsin Z, and dipeptidyl peptidase 2 were decreased in svPPA compared with controls. No proteins were abnormal in lvPPA. These results indicate a differential alteration of lysosomal proteins in the PPA variants, suggesting those with non-Alzheimer’s pathologies are more likely to show abnormal lysosomal function

    Superpotentials, Calabi-Yau algebras, and PBW deformations

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    The paper [9] by Bocklandt, Schedler and Wemyss considers path algebras with relations given by the higher derivations of a superpotential, giving a condition for such an algebra to be Calabi–Yau. In particular they show that the algebra , for V a finite dimensional vector space and G a finite subgroup of , is Morita equivalent to a path algebra with relations given by a superpotential, and is Calabi–Yau for . In this paper we extend these results, giving a condition for a PBW deformation of a Calabi–Yau, Koszul path algebra with relations given by a superpotential to have relations given by a superpotential, and proving these are Calabi–Yau in certain cases. We apply our methods to symplectic reflection algebras, where we show that every symplectic reflection algebra is Morita equivalent to a path algebra whose relations are given by the higher derivations of an inhomogeneous superpotential. In particular we show these are Calabi–Yau regardless of the deformation parameter. Also, for G a finite subgroup of not contained in , we consider PBW deformations of a path algebra with relations which is Morita equivalent to . We show there are no non-trivial PBW deformations when G is a small subgroup
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