Extension of non-minimal derivative coupling theory and Hawking radiation in black-hole spacetime

We study the greybody factor and Hawking radiation with a non-minimal derivative coupling between the scalar field and the curvature in the background of the slowly rotating Kerr-Newman black hole. Our results show that both the absorption probability and luminosity of Hawking radiation of the scalar field increase with the coupling. Moreover, we also find that for the weak coupling $\eta<\eta_c$, the absorption probability and luminosity of Hawking radiation decrease when the black hole's Hawking temperature decreases; while for stronger coupling $\eta>\eta_c$, the absorption probability and luminosity of Hawking radiation increase on the contrary when the black hole's Hawking temperature decreases. This feature is similar to the Hawking radiation in a $d$-dimensional static spherically-symmetric black hole surrounded by quintessence \cite{chensong}.Comment: 17 pages, 6 figures, 1 table, Title changed, Appendix changed, accepted by JHE

Análise integrada de sistemas de produção de tomateiro com base em indicadores edafobiológicos.

A análise integrada de indicadores edafobiológicos ligados ao manejo do solo constitui uma ferramenta importante para estimar níveis de sustentabilidade do agroecossistema, detectando-se pontos críticos para a devida correção de manejo. Essa ferramenta foi empregada na avaliação de sistemas de produção orgânica e convencional de tomate, em cultivo protegido e a campo aberto, no estado de São Paulo. Tomaram-se como referência solos de mata nativa e/ou pastagem natural, dependendo do local de estudo. Em Serra Negra, o solo sob sistema orgânico apresentou maior capacidade de campo e teor de argila dispersa mais baixo, indicativos da estabilidade dos agregados. No sistema convencional observou-se uma elevada condutividade elétrica, evidenciando a alta disponibilidade de sais solúveis. A análise de componentes principais (ACP) permitiu concluir que há maior grau de similaridade entre o solo sob sistema orgânico e aqueles das bases referenciais, com respeito aos indicadores químicos e biológicos. Constatou-se que C org, N total, polissacarídeos, FDA (hidrólise de diacetato de fluoresceína) e atividade enzimática de desidrogenase estão positivamente relacionados com o sistema orgânico, a mata nativa e a pastagem. Em contrapartida, a saturação por bases (V%), pH, teores de Mn, Mg e Ca, bem como a razão de dispersão estão inversamente relacionadas ao manejo orgânico. Já em Araraquara, os resultados da ACP distinguiram as áreas organicamente cultivadas das matas nativas, principalmente, com base nos indicadores biológicos

Impacto da exposição académica no estado de saúde de estudantes universitários

OBJECTIVE: To assess the impact of academic life on health status of university students. METHODS: Longitudinal study including 154 undergraduate students from the Universidade de Aveiro, Portugal, with at least two years of follow-up observations. Sociodemographic and behavioral characteristics were collected using questionnaires. Students' weight, height, blood pressure, serum glucose, serum lipids and serum homocysteine levels were measured. Regression analysis was performed using linear mixed-effect models, allowing for random effects at the participant level. RESULTS: A higher rate of dyslipidemia (44.0% vs. 28.6%), overweight (16.3% vs. 12.5%) and smoking (19.3% vs. 0.0%) was found among students exposed to the academic life when compared to freshmen. Physical inactivity was about 80%. Total cholesterol, high density lipoprotein-cholesterol (HDL-C), triglycerides, systolic blood pressure, and physical activity levels were significantly associated with gender (p<0.001). Academic exposure was associated with increased low density lipoprotein-cholesterol (LDL-C) levels (about 1.12 times), and marginally with total cholesterol levels (p=0.041). CONCLUSIONS: High education level does not seem to have a protective effect favoring a healthier lifestyle and being enrolled in health-related areas does not seem either to positively affect students' behaviors. Increased risk factors for non-transmissible diseases in university students raise concerns about their well-being. These results should support the implementation of health promotion and prevention programs at universities.OBJETIVO: Avaliar a influência da vida académica na saúde de estudantes universitários. MÉTODOS: Estudo longitudinal envolvendo 154 estudantes de graduação da Universidade de Aveiro, Portugal, por pelo menos dois anos de acompanhamento. Características sociodemográfi cas e comportamentais foram recordados, por meio de questionários. Foram medidos peso, altura,pressão arterial, glicemia, perfil lipídico e os níveis séricos de homocisteína dos alunos. Foi realizada análise de regressão com modelos lineares mistos considerando as medidas repetidas de cada sujeito. RESULTADOS: Estudantes expostos à vida académica, quando comparados àqueles de ingresso recente à universidade apresentaram proporção mais elevada de dislipidemia (44,0% versus 28,6%), sobrepeso (16,3% versus 12,5%) e tabagismo (19,3% versus 0,0%). No geral, foi observada alta proporção de sedentarismo (cerca de 80%). O colesterol total, lipoproteína de alta densidade, triglicérides, pressão arterial sistólica e níveis de atividade física apresentaram associação signifi cativa com o género (p < 0,001). A exposição académica apresentou-se associada com o aumento dos níveis das lipoproteínas de baixa densidade (cerca de 1,12 vezes), e marginalmente com os níveis de colesterol total (p = 0,041). CONCLUSÕES: Nem o alto nível de instrução parece ter papel protetor na adoção de estilo de vida saudável, tampouco o envolvimento com áreas de saúde muda o comportamento dos estudantes. Altas proporções de fatores de risco para doenças não-transmissíveis em jovens universitários podem afetar seu bem-estar. Os resultados podem servir de apoio às universidades no desenvolvimento de programas de prevenção e promoção da saúde

Impedance and initial magnetic permeability of gadolinium

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In the present work we report on measurements of the complex impedance and the magnetoimpedance of a textured sample of gadolinium metal. The preferential c -axis orientation of the Gd hexagonal structure is perpendicular to the long axis of the sample. From the experimental data, the complex initial magnetic permeability, mu = mu' + i mu '', was obtained as a function of temperature and frequency of the ac exciting current. We have found that the results for mu'(T) below the spin reorientation temperature may be described as a power law of the reduced temperature t = 1-T/T(SR), where T(SR) is the spin reorientation temperature. This behavior suggests that a genuine phase transition occurs at T(SR). Although the impedance displays a weak anomaly at the Curie temperature, T(C), magnetic measurements indicate that the ferromagnetic response of Gd extends up to this critical point. Thus, two different phases characterizes the cooperative magnetic state of this metal. The frequency dependent results for mu' and mu '' were fitted to a modified Debye formula and the obtained parameters allow us to discriminate between the contributions from domain-wall motion and from magnetization rotation. We obtain that the dynamical properties of the domain walls in Gd are governed by a broad distribution of frequencies whose average value diverge at T(SR). The isothermal magnetoimpedance measurements in temperatures smaller than T(SR) show an interesting plateau at low dc applied fields. This plateau is limited by a characteristic field H(K) whose magnitude decreases rapidly to nearly zero at T(SR), giving further support for the phase transition scenario at this temperature. (C) 2010 American Institute of Physics. [doi:10.1063/1.3288696]1075Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [04.0938.0

Brane-World Gravity

The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the \textit{d} extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak ($\sim$ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004) "Brane-World Gravity", 119 pages, 28 figures, the update contains new material on RS perturbations, including full numerical solutions of gravitational waves and scalar perturbations, on DGP models, and also on 6D models. A published version in Living Reviews in Relativit

Estimating Dengue Transmission Intensity from Case-Notification Data from Multiple Countries

Despite being the most widely distributed mosquito-borne viral infection, estimates of dengue transmission intensity and associated burden remain ambiguous. With advances in the development of novel control measures, obtaining robust estimates of average dengue transmission intensity is key for assessing the burden of disease and the likely impact of interventions.We estimated the force of infection (λ) and corresponding basic reproduction numbers (R0) by fitting catalytic models to age-stratified incidence data identified from the literature. We compared estimates derived from incidence and seroprevalence data and assessed the level of under-reporting of dengue disease. In addition, we estimated the relative contribution of primary to quaternary infections to the observed burden of dengue disease incidence. The majority of R0 estimates ranged from one to five and the force of infection estimates from incidence data were consistent with those previously estimated from seroprevalence data. The baseline reporting rate (or the probability of detecting a secondary infection) was generally low (<25%) and varied within and between countries.As expected, estimates varied widely across and within countries, highlighting the spatio-temporally heterogeneous nature of dengue transmission. Although seroprevalence data provide the maximum information, the incidence models presented in this paper provide a method for estimating dengue transmission intensity from age-stratified incidence data, which will be an important consideration in areas where seroprevalence data are not available

Observation of coherent hybrid reflection with synchrotron radiation

High resolution synchrotron radiation has been used to investigate the occurrence of coherent hybrid reflections (CHR) in the In0.49Ga0.51P/GaAs(001) structure. Several phi scans at the 002 layer reflection were carried out. The scanned phi intervals are correlated by the axis symmetry and [001] should present the same pattern. A break in the symmetry is observed due to constructive/destructive interference of the hybrid amplitudes with the amplitude from the 002 layer reflection. The effects of substrate miscut and interface distance are taken into account to explain the observed patterns. The application of CHR as a high sensitive tool to analyze epitaxial growth is discussed. (C) 1998 American Institute of Physics. [S0003-6951(98)03841-8].73152194219