4,189 research outputs found
Thermodynamic analysis of black hole solutions in gravitating nonlinear electrodynamics
We perform a general study of the thermodynamic properties of static
electrically charged black hole solutions of nonlinear electrodynamics
minimally coupled to gravitation in three space dimensions. The Lagrangian
densities governing the dynamics of these models in flat space are defined as
arbitrary functions of the gauge field invariants, constrained by some
requirements for physical admissibility. The exhaustive classification of these
theories in flat space, in terms of the behaviour of the Lagrangian densities
in vacuum and on the boundary of their domain of definition, defines twelve
families of admissible models. When these models are coupled to gravity, the
flat space classification leads to a complete characterization of the
associated sets of gravitating electrostatic spherically symmetric solutions by
their central and asymptotic behaviours. We focus on nine of these families,
which support asymptotically Schwarzschild-like black hole configurations, for
which the thermodynamic analysis is possible and pertinent. In this way, the
thermodynamic laws are extended to the sets of black hole solutions of these
families, for which the generic behaviours of the relevant state variables are
classified and thoroughly analyzed in terms of the aforementioned boundary
properties of the Lagrangians. Moreover, we find universal scaling laws (which
hold and are the same for all the black hole solutions of models belonging to
any of the nine families) running the thermodynamic variables with the electric
charge and the horizon radius. These scale transformations form a one-parameter
multiplicative group, leading to universal "renormalization group"-like
first-order differential equations. The beams of characteristics of these
equations generate the full set of black hole states associated to any of these
gravitating nonlinear electrodynamics...Comment: 51 single column pages, 19 postscript figures, 2 tables, GRG tex
style; minor corrections added; final version appearing in General Relativity
and Gravitatio
Benznidazole biotransformation and multiple targets in <i>Trypanosoma</i> cruzi revealed by metabolomics
<b>Background</b><p></p>
The first line treatment for Chagas disease, a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi, involves administration of benznidazole (Bzn). Bzn is a 2-nitroimidazole pro-drug which requires nitroreduction to become active, although its mode of action is not fully understood. In the present work we used a non-targeted MS-based metabolomics approach to study the metabolic response of T. cruzi to Bzn.<p></p>
<b>Methodology/Principal findings</b><p></p>
Parasites treated with Bzn were minimally altered compared to untreated trypanosomes, although the redox active thiols trypanothione, homotrypanothione and cysteine were significantly diminished in abundance post-treatment. In addition, multiple Bzn-derived metabolites were detected after treatment. These metabolites included reduction products, fragments and covalent adducts of reduced Bzn linked to each of the major low molecular weight thiols: trypanothione, glutathione, γ-glutamylcysteine, glutathionylspermidine, cysteine and ovothiol A. Bzn products known to be generated in vitro by the unusual trypanosomal nitroreductase, TcNTRI, were found within the parasites, but low molecular weight adducts of glyoxal, a proposed toxic end-product of NTRI Bzn metabolism, were not detected.<p></p>
<b>Conclusions/significance</b><p></p>
Our data is indicative of a major role of the thiol binding capacity of Bzn reduction products in the mechanism of Bzn toxicity against T. cruzi
The association of cold weather and all-cause and cause-specific mortality in the island of Ireland between 1984 and 2007
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.This article has been made available through the Brunel Open Access Publishing Fund.Background This study aimed to assess the relationship between cold temperature and daily mortality in the Republic of Ireland (ROI) and Northern Ireland (NI), and to explore any differences in the population responses between the two jurisdictions. Methods A time-stratified case-crossover approach was used to examine this relationship in two adult national populations, between 1984 and 2007. Daily mortality risk was examined in association with exposure to daily maximum temperatures on the same day and up to 6 weeks preceding death, during the winter (December-February) and cold period (October-March), using distributed lag models. Model stratification by age and gender assessed for modification of the cold weather-mortality relationship. Results In the ROI, the impact of cold weather in winter persisted up to 35 days, with a cumulative mortality increase for all-causes of 6.4% (95%CI=4.8%-7.9%) in relation to every 1oC drop in daily maximum temperature, similar increases for cardiovascular disease (CVD) and stroke, and twice as much for respiratory causes. In NI, these associations were less pronounced for CVD causes, and overall extended up to 28 days. Effects of cold weather on mortality increased with age in both jurisdictions, and some suggestive gender differences were observed. Conclusions The study findings indicated strong cold weather-mortality associations in the island of Ireland; these effects were less persistent, and for CVD mortality, smaller in NI than in the ROI. Together with suggestive differences in associations by age and gender between the two Irish jurisdictions, the findings suggest potential contribution of underlying societal differences, and require further exploration. The evidence provided here will hope to contribute to the current efforts to modify fuel policy and reduce winter mortality in Ireland
Position Specific & Positional Play Training in Elite Football
Those who have watched elite football across the last decade, realise that the game is more demanding than ever. This places more emphasis on training methods to prepare players for the rigors of the game. If we use the mantra of ‘train like you play’ it might be wise to complement existing practices with conditioning drills related to a players’ tactical role (position specific) and even elements of the club’s playing style/energetic profile (positional play). Thus, this piece will explore how such a stimulus can be incorporated into two areas of football conditioning: (1) team training and (2) individual end stage rehabilitation. Examples are presented from two European clubs
Positional Training in Elite Football: Context Matters
Those who have watched elite football across the last decade, realise that the game is more demanding than ever. This places more emphasis on training methods to prepare players for the rigors of the game. If we use the mantra of ‘train like you play’ it might be wise to complement existing practices with conditioning drills related to a players’ tactical role (e.g. position specific) and even elements of the club’s playing style/ energetic profile (e.g. positional play). Thus, this piece will explore how such a stimulus can be incorporated into two areas of football conditioning: (1) team training and (2) individual end stage rehabilitation. Examples are presented from two European clubs
Mineralisation of surfactants using ultrasound and the Advanced Fenton Process
The destruction of the surfactants, sodium dodecylbenzene sulfonate (DBS) and dodecyl pyridinium chloride (DPC), using an advanced oxidation process is described. The use of zero valent iron (ZVI) and hydrogen peroxide at pH = 2.5 (the advanced Fenton process), with and without, the application of 20 kHz ultrasound leads to extensive mineralisation of both materials as determined by total organic carbon (TOC)measurements. For DBS, merely stirring with ZVI and H2O2 at 20°C leads to a 51% decrease in TOC, but using 20 kHz ultrasound at 40°C, maintaining the pH at 2.5 throughout and adding extra amounts of ZVI and H2O2 during the degradation, then the extent of mineralisation of DBS is substantially increased to 93%. A similar result is seen for DPC where virtually no degradation occurs at 20°C, but if extra amounts of both ZVI and hydrogen peroxide are introduced during the reaction at 40°C and the pH is maintained at 2.5, then an 87% mineralisation of DPC is obtained. The slow latent remediation of both surfactants and the mechanism of degradation are also discussed
Dirac Equation with Spin Symmetry for the Modified P\"oschl-Teller Potential in -dimensions
We present solutions of the Dirac equation with spin symmetry for vector and
scalar modified P\"oschl-Teller potential within framework of an approximation
of the centrifugal term. The relativistic energy spectrum is obtained using the
Nikiforov-Uvarov method and the two-component spinor wavefunctions are obtain
are in terms of the Jacobi polynomials. It is found that there exist only
positive-energy states for bound states under spin symmetry, and the energy
levels increase with the dimension and the potential range parameter .Comment: 9 pages and 1tabl
Validation and optimization of AFP-based biomarker panels for early HCC detection in Latin America and Europe
Background: HCC is a major cause of cancer death worldwide. Serum biomarkers such as alpha-fetoprotein (AFP), protein induced by vitamin K absence-II, and the Gender, Age, AFP-L3, AFP, Des-gamma-carboxy prothrombin (GALAD) score have been recommended for HCC surveillance. However, inconsistent recommendations in international guidelines limit their clinical utility.Methods: In this multicenter study, over 2000 patient samples were collected in 6 Latin American and 2 European countries. The performance of the GALAD score was validated in cirrhotic cases, and optimized versions were tested for early-stage HCC and prediagnostic HCC detection.Results: The GALAD score could distinguish between HCC and cirrhosis in Latin American patients with an AUC of 0.76, sensitivity of 70%, and specificity of 83% at the conventional cutoff value of −0.63. In a European cohort, GALAD had an AUC of 0.69, sensitivity of 66%, and specificity of 72%. Optimizing the score in the 2 large multicenter cohorts revealed that AFP-L3 contributed minimally to early-stage HCC detection. Thus, we developed a modified GALAD score without AFP-L3, the ASAP (age, sex, AFP, and protein induced by vitamin K absence-II), which showed promise for early-stage HCC detection upon validation. The ASAP score also identified patients with cirrhosis at high risk for advanced-stage HCC up to 15 months before diagnosis (p < 0.0001) and differentiated HCC from hemangiomas, with a specificity of 100% at 71% sensitivity.Conclusion: Our comprehensive analysis of large sample cohorts validates the GALAD score’s utility in Latin American, Spanish, and Dutch patients for early-stage HCC detection. The optimized GALAD without AFP-L3, the ASAP score, is a good alternative and shows greater promise for HCC prediction
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