693 research outputs found
The ideal energy of classical lattice dynamics
We define, as local quantities, the least energy and momentum allowed by
quantum mechanics and special relativity for physical realizations of some
classical lattice dynamics. These definitions depend on local rates of
finite-state change. In two example dynamics, we see that these rates evolve
like classical mechanical energy and momentum.Comment: 12 pages, 4 figures, includes revised portion of arXiv:0805.335
On the probability of occurrence of rogue waves
A number of extreme and rogue wave studies have been conducted theoretically, numerically, experimentally and based on field data in the last years, which have significantly advanced our knowledge of ocean waves. So far, however, consensus on the probability of occurrence of rogue waves has not been achieved. The present investigation is addressing this topic from the perspective of design needs. Probability of occurrence of extreme and rogue wave crests in deep water is here discussed based on higher order time simulations, experiments and hindcast data. Focus is given to occurrence of rogue waves in high sea states
Targeting the GBA1 pathway to slow Parkinson disease: Insights into clinical aspects, pathogenic mechanisms and new therapeutic avenues
The GBA1 gene encodes the lysosomal enzyme glucocerebrosidase (GCase), which is involved in sphingolipid metabolism. Biallelic variants in GBA1 cause Gaucher disease (GD), a lysosomal storage disorder characterised by loss of GCase activity and aberrant intracellular accumulation of GCase substrates. Carriers of GBA1 variants have an increased risk of developing Parkinson disease (PD), with odds ratio ranging from 2.2 to 30 according to variant severity. GBA1 variants which do not cause GD in homozygosis can also increase PD risk. Patients with PD carrying GBA1 variants show a more rapidly progressive phenotype compared to non-carriers, emphasising the need for disease modifying treatments targeting the GBA1 pathway. Several mechanisms secondary to GCase dysfunction are potentially responsible for the pathological changes leading to PD. Misfolded GCase proteins induce endoplasmic reticulum stress and subsequent unfolded protein response and impair the autophagy-lysosomal pathway. This results in α-synuclein accumulation and spread, and promotes neurodegenerative changes. Preclinical evidence also shows that products of GCase activity can promote accumulation of α-synuclein, however there is no convincing evidence of substrate accumulation in GBA1-PD brains. Altered lipid homeostasis secondary to loss of GCase activity could also contribute to PD pathology. Treatments that target the GBA1 pathway could reverse these pathological processes and halt/slow the progression of PD. These range from augmentation of GCase activity via GBA1 gene therapy, restoration of normal intracellular GCase trafficking via molecular chaperones, and substrate reduction therapy. This review discusses the pathways associated with GBA1-PD and related novel GBA1-targeted interventions for PD treatment
Energy Transport in an Ising Disordered Model
We introduce a new microcanonical dynamics for a large class of Ising systems
isolated or maintained out of equilibrium by contact with thermostats at
different temperatures. Such a dynamics is very general and can be used in a
wide range of situations, including disordered and topologically inhomogenous
systems. Focusing on the two-dimensional ferromagnetic case, we show that the
equilibrium temperature is naturally defined, and it can be consistently
extended as a local temperature when far from equilibrium. This holds for
homogeneous as well as for disordered systems. In particular, we will consider
a system characterized by ferromagnetic random couplings . We show that the dynamics relaxes to steady states,
and that heat transport can be described on the average by means of a Fourier
equation. The presence of disorder reduces the conductivity, the effect being
especially appreciable for low temperatures. We finally discuss a possible
singular behaviour arising for small disorder, i.e. in the limit .Comment: 14 pages, 8 figure
Local safety of immediate reconstruction during primary treatment of breast cancer : direct-to-implant versus expander-based surgery
Introduction: After mastectomy, immediate breast reconstruction is paramount. With the growing number of nipple-sparing mastectomies, the chances of successful one-stage reconstruction with implants are also increasing. Local safety is one of the main issues. This study investigated the factors that could lead to major or minor complications after expander-based versus direct-to-implant (DTI) reconstruction. Methods: The studied factors were age, body mass index (BMI), hypertension, smoking, diabetes, type of mastectomy (nipple-sparing/total), implant size, neoadjuvant/adjuvant chemotherapy, and radiotherapy. The study sample included 294 immediate reconstructions over 3 years. The primary outcome was the incidence of complications, major or minor depending on the necessity of revision surgery. For the DTI pocket, we applied a variant of the conventional submuscular technique. Results: In DTI reconstructions (median follow-up 26 months), the complication rate was 17.2% (4.3% major and 12.8% minor) with no significant association with clinical variables. In expander-based reconstructions (median follow-up 19 months), the complication rate was 18.3% (12.5% major and 5.8% minor). Univariate analysis showed a significant association between overall complications and radiotherapy (P = 0.01) as well as between major complications and expander size (P < 0.005), BMI (P < 0.005), and radiotherapy (P < 0.01); radiotherapy and BMI retained significance in multivariate analysis. Neoadjuvant/adjuvant chemotherapy did not affect the complication rate. Conclusions: There was evidence of an association between major complications and clinical variables in the expander-based cohort. Larger expander size was a predictor of failure, especially combined with radiation. Direct-to-implant reconstruction proved to be safe. We describe a reliable method of reconstruction and a safe range of implant sizes even beyond 500 g
Triggering rogue waves in opposing currents
We show that rogue waves can be triggered naturally when a stable wave train
enters a region of an opposing current flow. We demonstrate that the maximum
amplitude of the rogue wave depends on the ratio between the current velocity,
, and the wave group velocity, . We also reveal that an opposing
current can force the development of rogue waves in random wave fields,
resulting in a substantial change of the statistical properties of the surface
elevation. The present results can be directly adopted in any field of physics
in which the focusing Nonlinear Schrodinger equation with non constant
coefficient is applicable. In particular, nonlinear optics laboratory
experiments are natural candidates for verifying experimentally our results.Comment: 5 pages, 5 figure
First-principles investigation of Nox and Sox adsorption on anatase-supported BaO and Pt overlayers
Cataloged from PDF version of article.We present a density functional theory investigation of the adsorption properties of NO and NO2 as well as SO2 and SO3 on BaO and Pt overlayers on anatase TiO2(001) surface. Mono layers, bilayers, and trilayers of BaO grow without strain-induced large scale reconstructions. While the bilayer and trilayer preserve, to a large extent, the NO2 adsorption characteristics of the clean BaO(100) surface, the effect of the support is evident in SO2 and SO3 adsorption energies, which are somewhat reduced with respect to the clean BaO(100) surface. When a Pt(100) layer is added on the TiO2 surface, four stable adsorption geometries are identified in the case of NO while NO2 is found to adsorb in only two configurations
A Two-Player Game of Life
We present a new extension of Conway's game of life for two players, which we
call p2life. P2life allows one of two types of token, black or white, to
inhabit a cell, and adds competitive elements into the birth and survival rules
of the original game. We solve the mean-field equation for p2life and determine
by simulation that the asymptotic density of p2life approaches 0.0362.Comment: 7 pages, 3 figure
Sex disparities in efficacy in covid-19 vaccines: A systematic review and meta-analysis
Sex differences in adaptive and innate immune responses have been shown to occur and anecdotal reports suggest that vaccine efficacy and safety may be sex-dependent. We investigated the influence of sex on the efficacy of COVID-19 vaccines through a systematic review and meta-analysis of clinical trials on COVID-19 vaccines. The safety profile of COVID-19 vaccines was also investigated. A systematic review included eligible articles published in three databases and three websites. A meta-analysis of available data, stratified by sex, was conducted. Statistical analysis was performed using the Hartung\u2013Knapp\u2013Sidik\u2013Jonkman method, as well as influence and heterogeneity analysis. Pooled analysis showed significantly higher efficacy, measured as the rate of new COVID-19 cases, in men compared to women in the vaccine group (OR = 0.67, 95% CI 0.48\u20130.94). No sex differences were found in the rate of new cases in the control group (OR = 0.92, 95% CI 0.78\u20131.09). Safety profiles derived from pharmacovigilance reports appear to indicate increased toxicity in women. In conclusion, evidence of a potential role of sex in COVID-19 vaccine efficacy was described. It strengthens the need to include sex as a core variable in the clinical trial design of COVID-19 vaccines
From Euclidean Geometry to Knots and Nets
This document is the Accepted Manuscript of an article accepted for publication in Synthese. Under embargo until 19 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s11229-017-1558-x.This paper assumes the success of arguments against the view that informal mathematical proofs secure rational conviction in virtue of their relations with corresponding formal derivations. This assumption entails a need for an alternative account of the logic of informal mathematical proofs. Following examination of case studies by Manders, De Toffoli and Giardino, Leitgeb, Feferman and others, this paper proposes a framework for analysing those informal proofs that appeal to the perception or modification of diagrams or to the inspection or imaginative manipulation of mental models of mathematical phenomena. Proofs relying on diagrams can be rigorous if (a) it is easy to draw a diagram that shares or otherwise indicates the structure of the mathematical object, (b) the information thus displayed is not metrical and (c) it is possible to put the inferences into systematic mathematical relation with other mathematical inferential practices. Proofs that appeal to mental models can be rigorous if the mental models can be externalised as diagrammatic practice that satisfies these three conditions.Peer reviewe
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