685 research outputs found

    Evaporation of (quantum) black holes and energy conservation

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    We consider Hawking radiation as due to a tunneling process in a black hole were quantum corrections, derived from Quantum Einstein Gravity, are taken into account. The consequent derivation, satisfying conservation laws, leads to a deviation from an exact thermal spectrum. The non-thermal radiation is shown to carry information out of the black hole. Under the appropriate approximation, a quantum corrected temperature is assigned to the black hole. The evolution of the quantum black hole as it evaporates is then described by taking into account the full implications of energy conservation as well as the back-scattered radiation. It is shown that, as a critical mass of the order of Planck's mass is reached, the evaporation process decelerates abruptly while the black hole mass decays towards this critical mass.Comment: 16 pages, 2 figure

    The mechanism why colliders could create quasi-stable black holes

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    It has been postulated that black holes could be created in particle collisions within the range of the available energies for nowadays colliders (LHC). In this paper we analyze the evaporation of a type of black holes that are candidates for this specific behaviour, namely, small black holes on a brane in a world with large extra-dimensions. We examine their evolution under the assumption that energy conservation is satisfied during the process and compare it with the standard evaporation approach. We claim that, rather than undergoing a quick total evaporation, black holes become quasi-stable. We comment on the (absence of) implications for safety of this result. We also discuss how the presence of black holes together with the correctness of the energy conservation approach might be experimentally verified.Comment: 16 pages, 3 figure

    Pandemic influenza control in Europe and the constraints resulting from incoherent public health laws

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    © 2010 Martin et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: With the emergence of influenza H1N1v the world is facing its first 21st century global pandemic. Severe Acute Respiratory Syndrome (SARS) and avian influenza H5N1 prompted development of pandemic preparedness plans. National systems of public health law are essential for public health stewardship and for the implementation of public health policy[1]. International coherence will contribute to effective regional and global responses. However little research has been undertaken on how law works as a tool for disease control in Europe. With co-funding from the European Union, we investigated the extent to which laws across Europe support or constrain pandemic preparedness planning, and whether national differences are likely to constrain control efforts. Methods: We undertook a survey of national public health laws across 32 European states using a questionnaire designed around a disease scenario based on pandemic influenza. Questionnaire results were reviewed in workshops, analysing how differences between national laws might support or hinder regional responses to pandemic influenza. Respondents examined the impact of national laws on the movements of information, goods, services and people across borders in a time of pandemic, the capacity for surveillance, case detection, case management and community control, the deployment of strategies of prevention, containment, mitigation and recovery and the identification of commonalities and disconnects across states. Results: Results of this study show differences across Europe in the extent to which national pandemic policy and pandemic plans have been integrated with public health laws. We found significant differences in legislation and in the legitimacy of strategic plans. States differ in the range and the nature of intervention measures authorized by law, the extent to which borders could be closed to movement of persons and goods during a pandemic, and access to healthcare of non-resident persons. Some states propose use of emergency powers that might potentially override human rights protections while other states propose to limit interventions to those authorized by public health laws. Conclusion: These differences could create problems for European strategies if an evolving influenza pandemic results in more serious public health challenges or, indeed, if a novel disease other than influenza emerges with pandemic potential. There is insufficient understanding across Europe of the role and importance of law in pandemic planning. States need to build capacity in public health law to support disease prevention and control policies. Our research suggests that states would welcome further guidance from the EU on management of a pandemic, and guidance to assist in greater commonality of legal approaches across states.Peer reviewe

    UV-B Exposure of Black Carrot (<i>Daucus carota</i> ssp. <i>sativus</i> var. <i>atrorubens</i>) Plants Promotes Growth, Accumulation of Anthocyanin, and Phenolic Compounds

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    © The Author(s).Black carrot (Daucus carota L. ssp. sativus var. atroburens) is a root vegetable with anthocyanins as major phenolic compounds. The accumulation of phenolic compounds is a common response to UV-B exposure, acting as protective compounds and as antioxidants. In the present study, black carrot plants grown under a 12-h photoperiod were supplemented with UV-B radiation (21.6 kj m−2 day−1) during the last two weeks of growth. Carrot taproots and tops were harvested separately, and the effect of the UV-B irradiance was evaluated in terms of size (biomass and length), total monomeric anthocyanin content (TMC), total phenolic content (TPC), and phytohormones levels. The results showed that UV-B irradiance promoted plant growth, as shown by the elevated root (30%) and top (24%) biomass, the increased TMC and TPC in the root (over 10%), and the increased TPC of the top (9%). A hormone analysis revealed that, in response to UV-B irradiance, the levels of abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) decreased in tops while the level of the cytokinins cis-zeatin (cZ) and trans-zeatinriboside (tZR) increased in roots, which correlated with an amplified growth and the accumulation of anthocyanins and phenolic compounds. Beyond the practical implications that this work may have, it contributes to the understanding of UV-B responses in black carrotThis research was funded by the Danish Ministry of Science, Innovation, and Education grant number 6111-00240B and “Fundación Séneca” of the Agency of Science and Technology of the Region of Murcia grant number 20405/SF/17.Peer reviewe

    Cricotracheal resection for adult subglottic stenosis : Factors predicting treatment failure

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    Objectives/Hypothesis Identify predictors of decannulation failure after cricotracheal resection (CTR) and thyrotracheal anastomosis (TTA) in patients with subglottic stenosis (SGS). Study Design Retrospective cohort study. Methods Charts of patients undergoing CTR and TTA for SGS at the University Health Network, Toronto, Ontario, Canada between 1988 and 2017 were reviewed. Patient, pathology, treatment, and outcome data were collected. The end points for statistical analysis were development of restenosis and permanent tracheostomy. Results One hundred fourteen patients (n = 114) were eligible for inclusion in this review. The mean age at primary resection was 46.9 years, 95 (83%) were females, and 19 (17%) were males. The rate of restenosis and permanent tracheostomy was 13% and 5%, respectively. Sixty-two patients (54%) underwent a CTR and TTA, and 52 patients (46%) underwent a CTR, laryngofissure, and TTA. Traumatic stenosis (odds ratio [OR] = 10.3, P = .017), longer T-tube duration (OR = 1.2, P = .011), combined glottic/subglottic stenosis (OR = 10.47, P = .010), start of the stenosis at the vocal cords (OR = 6.6, P = .029), postoperative minor complications (OR = 13.6, P = .028), and need for repeat surgery (OR = 44.1, P <.001) were associated with an increased risk of requiring permanent tracheostomy. Conclusions CTR and TTA are excellent surgical approaches for adult patients with subglottic stenosis. In this study, 5% of patients required permanent tracheostomy. Factors predicting treatment failure include traumatic stenosis, longer T-tube duration, combined glottic/subglottic stenosis, start of stenosis at the level of vocal cords, postoperative minor complications, and need for repeat surgery. Level of Evidence 4 Laryngoscope, 2019Peer reviewe

    D3-D7 Quark-Gluon Plasmas at Finite Baryon Density

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    We present the string dual to SU(Nc) N=4 SYM, coupled to Nf massless fundamental flavors, at finite temperature and baryon density. The solution is determined by two dimensionless parameters, both depending on the 't Hooft coupling λh\lambda_h at the scale set by the temperature T: ϵhλhNf/Nc\epsilon_h\sim\lambda_h Nf/Nc, weighting the backreaction of the flavor fields and δ~λh1/2nb/(NfT3)\tilde\delta\sim\lambda_h^{-1/2}nb/(Nf T^3), where nbnb is the baryon density. For small values of these two parameters the solution is given analytically up to second order. We study the thermodynamics of the system in the canonical and grand-canonical ensembles. We then analyze the energy loss of partons moving through the plasma, computing the jet quenching parameter and studying its dependence on the baryon density. Finally, we analyze certain "optical" properties of the plasma. The whole setup is generalized to non abelian strongly coupled plasmas engineered on D3-D7 systems with D3-branes placed at the tip of a generic singular Calabi-Yau cone. In all the cases, fundamental matter fields are introduced by means of homogeneously smeared D7-branes and the flavor symmetry group is thus a product of abelian factors.Comment: 27 pages; v2: 29 pages, 1 (new) figure, new section 4.4 on optical properties, references, comments added; v3: eq. (3.19), comments and a reference adde
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