Coalescence Rate of Supermassive Black Hole Binaries Derived from Cosmological Simulations: Detection Rates for LISA and ET

The coalescence history of massive black holes has been derived from cosmological simulations, in which the evolution of those objects and that of the host galaxies are followed in a consistent way. The present study indicates that supermassive black holes having masses greater than $\sim 10^{9} M_{\odot}$ underwent up to 500 merger events along their history. The derived coalescence rate per comoving volume and per mass interval permitted to obtain an estimate of the expected detection rate distribution of gravitational wave signals ("ring-down") along frequencies accessible by the planned interferometers either in space (LISA) or in the ground (Einstein). For LISA, in its original configuration, a total detection rate of about $15 yr^{-1}$ is predicted for events having a signal-to-noise ratio equal to 10, expected to occur mainly in the frequency range $4-9 mHz$. For the Einstein gravitational wave telescope, one event each 14 months down to one event each 4 years is expected with a signal-to-noise ratio of 5, occurring mainly in the frequency interval $10-20 Hz$. The detection of these gravitational signals and their distribution in frequency would be in the future an important tool able to discriminate among different scenarios explaining the origin of supermassive black holes.Comment: 18 pages, 7 figures, to appear in the IJMP

Are Neutron-Rich Elements Produced in the Collapse of Strange Dwarfs ?

The structure of strange dwarfs and that of hybrid stars with same baryonic number is compared. There is a critical mass (M~0.24M_sun) in the strange dwarf branch, below which configurations with the same baryonic number in the hybrid star branch are more stable. If a transition occurs between both branches, the collapse releases an energy of about of 3x10^{50} erg, mostly under the form of neutrinos resulting from the conversion of hadronic matter onto strange quark matter. Only a fraction (~4%) is required to expel the outer neutron-rich layers. These events may contribute significantly to the chemical yield of nuclides with A>80 in the Galaxy, if their frequency is of about one per 1500 years.Comment: Accepted for publication in IJMP

Quark core formation in spinning-down pulsars

Pulsars spin-down due to magnetic torque reducing its radius and increasing the central energy density. Some pulsar which are born with central densities close to the critical value of quark deconfinement may undergo a phase transition and structural re-arrengement. This process may excite oscillation modes and emmit gravitational waves. We determine the rate of quark core formation in neutron stars using a realistic population synthesis code.Comment: Proceedings of the 2nd International Workshop on Astronomy and Relativistic Astrophysics, to appear in IJMP

The compound Poisson limit ruling periodic extreme behaviour of non-uniformly hyperbolic dynamics

We prove that the distributional limit of the normalised number of returns to small neighbourhoods of periodic points of non-uniformly hyperbolic dynamical systems is compound Poisson. The returns to small balls around a fixed point in the phase space correspond to the occurrence of rare events, or exceedances of high thresholds, so that there is a connection between the laws of Return Times Statistics and Extreme Value Laws. The fact that the fixed point in the phase space is a repelling periodic point implies that there is a tendency for the exceedances to appear in clusters whose average sizes is given by the Extremal Index, which depends on the expansion of the system at the periodic point. We recall that for generic points, the exceedances, in the limit, are singular and occur at Poisson times. However, around periodic points, the picture is different: the respective point processes of exceedances converge to a compound Poisson process, so instead of single exceedances, we have entire clusters of exceedances occurring at Poisson times with a geometric distribution ruling its multiplicity. The systems to which our results apply include: general piecewise expanding maps of the interval (Rychlik maps), maps with indifferent fixed points (Manneville-Pomeau maps) and Benedicks-Carleson quadratic maps.Comment: To appear in Communications in Mathematical Physic

Late energy injection and cosmological constraints in axino dark matter scenarios

Taking into account effects of late energy injection, we examine big bang nucleosynthesis (BBN) constraints on axino dark matter scenarios with long-lived charged sleptons. We calculate 4-body slepton decays into the axino, a lepton, and a quark–antiquark pair since they govern late hadronic energy injection and associated BBN constraints. For supersymmetric hadronic axion models, we present the obtained hadronic BBN constraints and show that they can be more restrictive than the ones associated with catalyzed BBN via slepton-bound-state formation. From the BBN constraints on hadronic and electromagnetic energy release, we find new upper limits on the Peccei–Quinn scale

Colite pseudomembranosa : uma casuística de internamentos

Introduction: pseudomembranous colitis (PMC) is an infectious disease that generally begins after antibiotic treatment. Objectives: Characterize the patients with PMC in two Services of a Central Hospital. Material and Methods: we considered the patients admitted in a Medicine (MS) and in a Gastroenterology (GES) Service with primary or secondary diagnosis of PMC, between January/1995 and July/2003 and registered the age, gender, clinical presentation, antibiotics (AB) and other risk factors, diagnostic procedures, complications and treatment. Results: we considered 80 patients (43 - GES and 37 - MS); Mean age - 68,6 ± 17,7 years; 52,5% were male; Antibiotic treatment in the previous 3 months - 85%; Mean time of antibiotic treatment - 10,5 ± 6,1 days. Most Commonly Involved Antibiotics: cephalosporins, amoxicillin/clavulanic acid and quinolones. Associated risk factors: renal insufficiency (22,5%); cardiac insufficiency (22,5%); previously dependent patient ( 36,3%). Diagnostic procedures: toxin search-58 patients ( in 36 ), colonoscopy - 62 ( in 53); culture - 23 (in 17 ). The mortality rate was 18,8% (n = 15); recurrence rate - 10% (n = 8). Therapeutics: metronidazol - 37 patients (46,3%); vancomycin - 24 (30%); metronidazol + vancomycin – 12 (15%). Differences Between Services: mean age (MS - 72,9 and GES - 64,9); admission criteria (GES - intestinal disorders, MS – respiratory infections); diagnostic procedures (colonoscopy more frequent in GES); therapeutic options (MS - metronidazol; GES - vancomycin and metronidazol + vancomycin). Conclusions: PMC is more common in older patients that were generally submitted to previous antibiotic treatment, especially with ß-lactamics. Considering two distinct Services we observed differences concerning age, co-morbility and risk factors that implied distinct diagnostic and therapeutic approaches

Crescimento inicial e eficiência fotoquímica de mangueiras cultivadas em solo contendo lama do rio doce

RESUMO Este trabalho avaliou os efeitos da lama oriunda do leito do Rio Doce (19º4154550 S, 40º 07 43960 O), sobre a atividade fotossintética e o crescimento de três cultivares enxertadas de Mangífera Indica L. em estádio de muda. O Rio Doce, ao longo dos anos, vem sofrendo com a deposição de materiais contaminados oriundos da extração do minério de ferro. Essa situação agravou-se com o rompimento da barragem de Mariana-MG em novembro de 2015, quando milhões de metros cúbicos de rejeitos de mineração foram depositados e arrastados ao longo da bacia do Rio Doce. Até o momento, pouco se sabe sobre a magnitude do impacto causado pela lama no desenvolvimento das espécies vegetais. A atividade agrícola das regiões próximas ao desastre foi altamente prejudicada, os rejeitos compactaram o solo tornando-o infértil. Entender a fisiologia das plantas submetidas a essa nova realidade ambiental é primordial para as estratégias de recuperação tanto do âmbito ambiental quanto socioeconômico. Para isso, três diferentes cultivares de Mangífera indica L. com destaque no mercado de frutíferas foram utilizadas para avaliar os efeitos dos resíduos de mineração sobre o crescimento e a vitalidade das plantas. Os tratamentos foram caracterizados de acordo com as cultivares (Rosa, Tommy Atkins e Palmer) submetidas a três concentrações dos resíduos de mineração (0%, 20% e 50) presente no substrato a base de turfa. Essas concentrações foram caracterizadas de acordo com as propriedades físicas e químicas. Simultaneamente, as análises nutricionais das folhas das cultivares foram avaliadas. As medidas de crescimento e as análises fotossintéticas foram realizadas mensalmente, entre outubro de 2016 a outubro de 2017. No último mês de análise foi realizada a contagem dos primeiros frutos das cultivares estabelecendo-os em ter categorias de acordo com seu tamanho. Os parâmetros que melhor representaram os efeitos dos resíduos de mineração no desenvolvimento das mudas foram o PITOTAL (Indice de desempenho total da etapa fotoquímica da fotossíntese) e o PIABS (índice de desempenho do FSII). Os danos causados foram evidentes na cv. Rosa, as análises de crescimento, os índices de clorofila, as curvas OJIPs normalizadas juntamente com os parâmetros do teste JIP utilizados, corroboram essa afirmação. Através dessas análises também foi possível observar que as cultivares Tommy Atkins e Palmer não apresentaram redução significativas em resposta ao aumento das concentrações residuais. Os resultados dos macro e micronutrientes foliares revelaram que a cv.Rosa (Tratamento 50%) apresentou níveis tóxicos de Mn, podendo ter contribuído para a severidade do estresse observado. Os resultados indicaram, frente aos efeitos causados pelos resíduos oriundo do leito do Rio Doce, que a cv.Rosa apresentou os mais severos sintomas, resultando em mudas menos desenvolvidas e com uma produtividade inicial reduzida, enquanto as cultivares Tommy Atkins e Palmer demonstraram alta tolerância ao efeitos da contaminação. Palavras-chave: Desastre, fluorescência, crescimento, compactação, mangueira