877 research outputs found

    Looking for a time independent Hamiltonian of a dynamical system

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    In this paper we introduce a method for finding a time independent Hamiltonian of a given dynamical system by canonoid transformation. We also find a condition that the system should satisfy to have an equivalent time independent formulation. We study the example of damped oscillator and give the new time independent Hamiltonian for it, which has the property of tending to the standard Hamiltonian of the harmonic oscillator as damping goes to zero.Comment: Some references added, LATEX fixing

    3d defects in 5d: RG flows and defect F-maximization

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    We use a combination of AdS/CFT and supersymmetric localization to study codimension-2 defects in 5d SCFTs and their gauge theory deformations. The 5d SCFTs are engineered by (p,q)(p,q) 5-brane webs, with defects realized by D3-branes ending on the 5-brane webs. We obtain the defect free energies and find that gauge theory descriptions of the combined 5d/3d systems can be connected to the UV defect SCFTs through a form of F-maximization which extremizes over different gauge theory defects. This leads to a match between the defect free energies obtained from supersymmetric localization in the gauge theories on the one hand and string theory results on the other. We extend this match to defect RG flows.Comment: 40 pages, 10 figure

    Evaluation of some habitat improvement actions in a Mediterranean area through observation of reared pheasant and red-legged partridge land uses

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    Red-legged partridge (Alectoris rufa) and pheasant (Phasianus colchicus) have suffered population decline in the last decades. Research suggested that decline is mainly related to the intensification of agricultural techniques and land abandonment. We evaluated habitat use and distribution of reared red-legged partridge pairs and cock pheasants in an estate representative of most of the agricultural Mediterranean areas from 2007 to 2012. Particular attention has been addressed to the effect of artificial habitat improvement actions (HIAs) and other management options such as supplemental feeding and hedgerows maintenance. We compared habitat use with its availability and analyzed spatial distribution by comparing points with pheasant cocks and partridge pairs with random ones. HIAs were used more than their availability by both species and resulted to have an important role in their distribution like hedgerows. Feeders resulted to have a strong effect on pheasant distribution, but not on pairs of red-legged partridges. Our results show that habitat management could be a fundamental tool for game-bird conservation, though the effects of feeders on red-legged partridge distribution need to be further investigated

    Versal deformations of a Dirac type differential operator

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    If we are given a smooth differential operator in the variable x∈R/2πZ,x\in {\mathbb R}/2\pi {\mathbb Z}, its normal form, as is well known, is the simplest form obtainable by means of the \mbox{Diff}(S^1)-group action on the space of all such operators. A versal deformation of this operator is a normal form for some parametric infinitesimal family including the operator. Our study is devoted to analysis of versal deformations of a Dirac type differential operator using the theory of induced \mbox{Diff}(S^1)-actions endowed with centrally extended Lie-Poisson brackets. After constructing a general expression for tranversal deformations of a Dirac type differential operator, we interpret it via the Lie-algebraic theory of induced \mbox{Diff}(S^1)-actions on a special Poisson manifold and determine its generic moment mapping. Using a Marsden-Weinstein reduction with respect to certain Casimir generated distributions, we describe a wide class of versally deformed Dirac type differential operators depending on complex parameters

    Further insights on predictors of environmental tobacco smoke exposure during the pediatric age

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    Background: The smoking ban in public places has reduced Environmental Tobacco Smoke (ETS) exposure for non-smokers, but despite this, domestic environments still remain places at high risk of exposure, and, today, about 40% of children worldwide are exposed to ETS at home. The aims of the study are to investigate the contribution of several factors on ETS exposure among a group of Italian children and to evaluate the changes in smoking precautions adopted at home when the smoker is the mother, the father, or both parents, respectively. Methods: A cross-sectional study was performed on a sample of 519 Italian schoolchildren. Information was collected via a questionnaire. Results: 41.4% of the participants lived with at least one smoker. Almost half of the children exposed to ETS lived with one or more smokers who do not observe any home smoking ban. Lower maternal or paternal educational levels significantly increase the risk of ETS exposure at home and the “worst case” is represented by both parents who smoke. Conclusions: More effective preventive interventions are needed to protect children from ETS exposure. Some interventions should be specifically dedicated to smokers with a low educational level and to mothers that smoke

    Gait analysis advancements: rehabilitation value and new perspectives from forensic application

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    The clinical and rehabilitation value of gait analysis is remarkable and indisputable and poised to grow as technological advancements unfold. This article aims to shed light on the advances in how gait is assessed, enabling those who have suffered an injury impairing their motor skills to be diagnosed more accurately and efficiently as well as to compare the hallmarks of rehabilitative and forensic gait analysis. The authors have conducted an analysis of relevant papers (published between 1967 and 2020) from a medicolegal perspective, cited in PubMed, MEDLINE, Cochrane Library, EMBASE, and available recommendations for the legal application of such techniques. Moreover, considering the use of gait analysis as a forensic tool, this study broadens the scope of research by including search engines, legal databases, and court filings (DeJure, Lexis Nexis, Justia) between 2000 and 2022. The instrumental assessment of movement (Gait Analysis) has come to constitute an essential analytical tool for the biomedical sector to objectively and accurately assess human movement and posture. The article is also aimed at elaborating differences and similarities between clinical and forensic gait analysis. When it comes to the forensic applicability of gait analysis and its evidentiary value, however, there is a pressing need for a review of its scientific basis. Therefore, it is necessary to conduct a thorough evaluation of its use in legal practice, as stressed in scientific literature and surveys. It is of utmost importance to highlight the procedural and assessment standards currently applied to forensic gait analysis, to evaluate its strengths and weaknesses, and to achieve standardized guidelines based on broad scientific consensus

    Lagrangian versus Quantization

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    We discuss examples of systems which can be quantized consistently, although they do not admit a Lagrangian description.Comment: 8 pages, no figures; small corrections, references adde

    Regenerative potential of DPSCs and revascularization. direct, paracrine or autocrine effect?

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    A new source of mesenchymal stem cells has recently been discovered, the so-called dental pulp derived stem cells (DPSCs) which therefore could represent potentially tools for regenerative medicine. DPSC originate from the neural crest and are physiologically involved in dentin homeostasis; moreover, they contribute to bone remodeling and differentiation into several tissues including cartilage, bone, adipose and nervous tissues. DPSCs have also been shown to influence the angiogenesis process, for example through the release of secretory factors or by differentiating into vascular and/or perivascular cells. Angiogenesis, that has a pivotal role in tissue regeneration and repair, is defined as the formation of new vessels from preexisting vessels and is mediated by mutual and reciprocal interactions between endothelial cells and perivascular cells. It is also known that co-cultures of perivascular and endothelial cells (ECs) can form a vascular network in vitro and also in vivo. Since DPSCs seem to have characteristics similar to pericytes, understanding the possible mechanism of interaction between DPSCs and ECs during neo-angiogenesis is dramatically important for the development of advanced clinical application in the field of regeneration. Graphical abstract: [Figure not available: see fulltext.

    Adverse Events Related to Vaccination (VAEs): How to Manage the Further Doses of Immunization and Parents’ Hesitancy

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    This study supports the evidence that after vaccine‐related reactions, it is still possible to carry out the immunization protocol
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