635 research outputs found
Convex Neighbourhoods and Complete Finsler Spaces
In this paper, it is shown that a large set of connections on a suitable
sub-bundle of the tangent bundle of a Finsler Manifold can be used to study all
the properties of convex neighbourhoods with respect to the Finsler Metric,
which are needed to see that any Complete Finsler Space is Geodesically
Connected.Comment: 17 page
Covariant second variation for first order Lagrangians on fibered manifolds II: generalized curvature and Bianchi identities
The notion of generalized curvature structures ensuing from the second
variation of a (firstâorder) Lagrangian is extensively discussed. It is shown that generalized curvature structures satisfy appropriate (generalized) Bianchi identities. Formulae applicable to curvature Lagrangians are developed in great detail. Examples are taken from the theory of generalized harmonic Lagrangians
Concentrations of some toxic and trace elements in wild boar (Sus scrofa) organs and tissues in different areas of the Province of Viterbo, Central Italy
The aim of the present study was to determine heavy metal reference levels for exposure and risk assessment studies on a local scale. We measured lead (Pb), chromium (Cr), zinc (Zn), copper (Cu) and cadmium (Cd) content in edible tissues and organs of wild boars harvested in dif- ferent areas of the Province of Viterbo, Central Italy. The average levels of cadmium recorded in 75 wild boars were 0.085, 0.079 and 1.052 mg Cd kgâ1 wet weight (w.w.) in the liver, muscle and kidney, respectively. The majority of the muscle samples and some of the liver samples contained levels of heavy metal that were over the legal limit [EU Maximum Residue Levels (MRLs)] for pigs. Our data are similar to or lower than the val- ues reported in most of the available literature. For Pb concentration, the average values record- ed were 0.318, 0.126 and 0.298 mg kgâ1 w.w. in the liver, muscle and kidney, respectively. The sam- ples that were non-compliant with regulatory limits (MRLs) for pigs were registered only for muscle. Available data on the presence of Pb con- tent in game meat report lower values than ours, most likely because the area around the bullet path was avoided while sampling. The average values of total Cr were 0.141, 0.139 and 0.097 mg kgâ1 w.w. in the liver, muscle and kidney, respec- tively. For Zn, the mean values were 49.76, 53.21 and 32.46 mg kgâ1 w.w. in the liver, muscle and kidney, respectively. Cu content was 46.12, 12.20 and 5.64 mg Cu kgâ1 w.w. in the liver, muscle and kidney, respectively. The results obtained have been validated on the basis of the scarce and inconsistent Italian literature available and on international studies
Cadmium, Lead and Chromium in Large Game: A Local-Scale Exposure Assessment for Hunters Consuming Meat and Liver of Wild Boar.
Theoretical model for the superconducting and magnetically ordered borocarbides
We present a theory of superconductivity in presence of a general magnetic
structure in a form suitable for the description of complex magnetic phases
encountered in borocarbides. The theory, complemented with some details of the
band structure and with the magnetic phase diagram, may explain the nearly
reentrant behaviour and the anisotropy of the upper critical field of HoNi2B2C.
The onset of the helical magnetic order depresses superconductivity via the
reduction of the interaction between phonons and electrons caused by the
formation of magnetic Bloch states. At mean field level, no additional
suppression of superconductivity is introduced by the incommensurability of the
helical phase.Comment: 8 pages, 2 figures. Published version, one important reference adde
Nicotinic Acetylcholine Receptor Alterations in Autism Spectrum Disorders â Biomarkers and Therapeutic Targets
Trunk motion analysis: a systematic review from a clinical and methodological perspective
INTRODUCTION: This systematic literature review aims to check the current state of affairs of non-gait-related optoelectronic trunk movement analysis; results have been analyzed from a clinical and a methodological perspective.
EVIDENCE ACQUISITION: Extensive research was performed on all papers published until December 31st, 2015, dealing with trunk movement analysis assessed by optoelectronic systems, excluding those related to gait. The research was performed on the 14th of January 2016 on three databases: Scopus, Science Direct and Pubmed. A reference search and expert consultation were also performed.
EVIDENCE SYNTHESIS: Out of a total number of 8431 papers, 45 were deemed relevant: they included 1334 participants, 57.9% healthy, with age range 8-85. Few studies considered the whole trunk, and none focused on each vertebra independently: the trunk was almost always divided into three segments. Thirteen studies included 20 or more markers. Most of the papers focused mainly on the biomechanics of various movements; the lumbar area and low back pain were the most studied region and pathology respectively.
CONCLUSIONS: This study has shown the relative scarcity of current literature focusing on trunk motion analysis. In clinical terms, results were sparse. The only quite well represented group of papers focused on the lumbar spine and pathologies, but the scarcity of individuals evaluated make the results questionable. The use of optoelectronic systems in the evaluation of spine movement is a growing research area. Nevertheless, no standard protocols have been developed so far. Future research is needed to define a precise protocol in terms of number and position of markers along the spine and movements and tasks to be evaluated
Ultrasmall SnO2 directly grown on commercial carbon black: a versatile composite material for Li-based energy storage
Herein, we propose a hassle-free approach to prepare SnO2/C composite using a simple, fully sustainable, and economic synthesis process, in which tin oxide is in situ nucleated on commercial carbon black C-NERGYTM Super C45 (Imerys Graphite & Carbon) in form of homogenously distributed nanoparticles. The synthesis is carried out by wet impregnation without any acid treatment or high temperature process. We focused on the presence of the existing oxygen species on the carbon surface that are accessible for tin and promote SnâOâC interactions, suggesting synergies between the two components, with an active role of the carbon support in the SnO2 conversion reaction.
On one hand, in Li-ion technology, development of high-performance SnO2 anodes is hampered by its peculiar electrochemical behavior, characterized by two processes: conversion and alloying reactions. The conversion reaction being irreversible leads to specific capacities lower than theoretical, however rational design of nanosized SnO2 can mitigate this issue, though SnO2 low conductivity and electrode pulverization justify the need of carbon matrices. Some carbon structures proved to be strongly effective at laboratory-scale, but most are too expensive or complicated to obtain for scaling-up. Presence of oxygen species on C45 surface, accessible to tin, prevent fast formation of Li2O, allowing to achieve high capacity and extreme electrode stability. The assembled cells with SnO2 /C45 exhibit for more than 400 cycles the reversible capacity of 560 mA h gâ1 per pure SnO2 (after subtracting C45 contribution) at 1C, demonstrating prolonged cycling operation thus providing an interesting opportunity for scalable production of stable and high-capacity battery anodes alternatively to graphite [1].
On the other hand, developing efficient and low cost electrocatalysts for ORR is
fundamental to bring the Li-O2 technology closer to practical applications. The obtained
composite material shows an optimal ORR activity with a final reduction mechanism
following the 4 electrons pathway. This is confirmed in Li-O2 cells, indeed compared to
pure C45 air-cathodes, the composite cathodes lead to the formation of much more
reversible film-like discharge products, allowing for reduced overvoltage and therefore
improved cycling performances both at the high current density of 0.5 mA cm-2 with more
than 70 cycles and in prolonged discharge/charge conditions with over 1250 h of operation
at the fixed capacity of 2.5 mAh cm-2 [2].
Considering the fast and inexpensive method used to prepare SnO2/C45, these results,
in terms of reversible capacities and long cycling stability, are competitive among others
obtained for SnO2-based materials synthetized by other methods such as hydrothermal, sonochemical, solvothermal, etc. All these considerations make the synthetic route reported a suitable and interesting approach for large scale production.
References
1. D
Phenomenological Theory of Superconductivity and Magnetism in HoDyNiBC
The coexistence of the superconductivity and magnetism in the
HoDyNiBC is studied by using Ginzburg-Landau theory. This
alloy shows the coexistence and complex interplay of superconducting and
magnetic order. We propose a phenomenological model which includes two magnetic
and two superconducting order parameters accounting for the multi-band
structure of this material. We describe phenomenologically the magnetic
fluctuations and order and demonstrate that they lead to anomalous behavior of
the upper critical field. The doping dependence of in
HoDyNiBC showing a reentrance behavior are analyzed
yielding a very good agreement with experimental data.Comment: 4 pages, 3 figures, REVTeX, submitted to PR
Erectile dysfunction and angiographic extent of coronary artery disease in type II diabetic patients
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