1,307 research outputs found

    Stability of multidimensional black holes: complete numerical analysis

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    We analyze evolution of gravitational perturbations of D-dimensional Schwarzschild, Reissner-Nordstr\"om, and Reissner-Nordstrom-de Sitter black holes. It is known that the effective potential for the scalar type of gravitational perturbations has negative gap near the event horizon. This gap, for some values of the parameters Q (charge), Lambda (cosmological constant) and D (number of space-time dimensions), cannot be removed by S-deformations. Thereby, there is no proof of (in)stability for those cases. In the present paper, by an extensive search of quasinormal modes, both in time and frequency domains, we shall show that spherically symmetric static black holes with arbitrary charge and positive (de Sitter) lambda-term are stable for D=5, 6, >...11. In addition, we give a complete numerical data for all three types (scalar, vector and tensor) of gravitational perturbations for multi-dimensional black holes with charge and Lambda-term. The influence of charge, Lambda-term and number of extra dimensions on black hole quasinormal spectrum is discussed.Comment: 12 pages, RevTe

    Quasi-normal modes of the scalar hairy black hole

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    We calculate QNMs of the scalar hairy black hole in the AdS background using Horowitz-Hubeny method for the potential that is not known in analytical form. For some black hole parameters we found pure imaginary frequencies. Increasing of the scalar field mass does not cause the imaginary part to vanish, it reaches some minimum and then increases, thus in the case under consideration the infinitely long living modes (quasi-resonances) do not appear.Comment: 17 pages, 17 figures, LaTe

    Quasinormal modes of black holes immersed in a strong magnetic field

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    We found quasinormal modes, both in time and frequency domains, of the Ernst black holes, that is neutral black holes immersed in an external magnetic field. The Ernst solution reduces to the Schwarzschild solution, when the magnetic field vanishes. It is found that the quasinormal spectrum for massless scalar field in the vicinity of the magnetized black holes acquires an effective "mass" μ=2Bm\mu = 2 B m, where m is the azimuthal number and B is parameter describing the magnetic field. We shall show that in the presence of a magnetic field quasinormal modes are longer lived and have larger oscillation frequencies. The perturbations of higher dimensional magnetized black holes by Ortaggio and of magnetized dilaton black holes by Radu are considered.Comment: 5 pages, RevTe

    Analysis of the relationship between the KRAS G12V oncogene and the Hippo effector YAP1 in embryonal rhabdomyosarcoma

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    The authors acknowledge funding from Sarcoma UK, grant number: SUK09.2015.Peer reviewedPublisher PD

    Localization and Broadband Follow-Up of the Gravitational-Wave Transient GW150914

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    A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser InterferometerGravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimatesof the time, significance, and sky location of the event were shared with 63 teams of observers covering radio,optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter wedescribe the low-latency analysis of the GW data and present the sky localization of the first observed compactbinary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-rayCoordinates Network circulars, giving an overview of the participating facilities, the GW sky localizationcoverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger,there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadbandcampaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broadcapabilities of the transient astronomy community and the observing strategies that have been developed to pursueneutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-upcampaign are being disseminated in papers by the individual teams

    Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

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    Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

    CONSTRUÇÃO E VALIDAÇÃO DE INSTRUMENTO PARA AVALIAÇÃO DAS MEDIDAS DE BIOSSEGURANÇA EM BIOTERRORISMO PELOS BOMBEIROS

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    Objetivo: Este estudo teve como objetivo desenvolver e validar um instrumento de avaliação das medidas de Biossegurança adotadas pelos bombeiros militares, para a contenção dos agentes biológicos frente a um evento de bioterrorismo. Métodos: Tratou-se de um estudo descritivo de abordagem quantitativa, de desenvolvimento metodológico e do tipo de validação de conteúdo de um instrumento de avaliação. O estudo foi dividido nas fases de desenvolvimento e validação do instrumento. Para o desenvolvimento do instrumento foram feitas revisões da literatura e para a validação do instrumento foi utilizado o método Delphi. Para o estudo foram incluídos 6 juízes que avaliaram o instrumento através da escala numérica tipo Likert. Resultados: Os juízes avaliaram que o instrumento proposto está bem estruturado, possuindo boa clareza e coesão de escrita, com aplicabilidade no campo de estudo e de grande relevância, principalmente em vista a ausência desse tipo de instrumento para a população de bombeiros militares. Para avaliar a concordância entre os juízes foi utilizado o índice de Validade de Conteúdo, que alcançou 98% de concordância e o Índice de Fidedignidade Interavaliadores, que alcançou os conceitos bom e muito bom, mostrando baixa variância das respostas dos juízes, sendo estatisticamente válido. Conclusão: O estudo descreveu o processo de construção e validação do instrumento, provando ser apropriado e confiável para ser utilizado

    Methodology for a Comprehensive Health Impact Assessment in Water Supply and Sanitation Programmes for Brazil

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    Based on the broader concept of health proposed by the Pan-American Health Organization/World Health Organization (PAHO/ WHO), 2018, and the absence in the literature of indices that translate the causal relationship between sanitation and health, a methodology for assessing the health impact of a water and sanitation programmes, known as a Health Impact Assessment (HIA), was developed, specifically in the Brazilian context, and focused on a school in the northeast of the country. Through exploratory and descriptive evidence, and using documentary research as a method, a retrospective survey was carried out from 2000 to 2022 using documents proposing evaluation methodologies. A single document was found to fit the research objective, which was used to develop the proposed HIA methodology. Development of the methodology consisted of two stages: definition of the health dimensions and selection of the indicators making up each dimension. The HIA methodology was then applied to a school in northeast Brazil to test its use, before a water-efficient management intervention was going to be used. The overall score of 46% indicated that there was room for improvement, which the new management approach could facilitate. This methodology is therefore proposed to be an instrument for the evaluation of public water and sanitation policies, thus assisting managers in the decision-making process and in guiding sanitation programs and plans
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