Cavity effects on the Fermi velocity renormalization in a graphene sheet

Recently, in the literature, it was shown that the logarithmic renormalization of the Fermi velocity in a plane graphene sheet (which, in turn, is related to the Coulombian static potential associated to electrons in the sheet) is inhibited by the presence of a single parallel conducting plate. In the present paper, we investigate the situation of a suspended graphene sheet in a cavity formed by two conducting plates parallel to the sheet. The effect of a cavity on the interaction between electrons in the graphene is not merely the addition of the effects of each plate individually. From this, one can expect that the inhibition of the renormalization of the Fermi velocity generated by a cavity is not a mere addition of the inhibition induced by each single plate. In other words, the simple addition of the result for the inhibition of the renormalization of the Fermi velocity found in the literature for a single plate could not be used to predict the exact behavior of the inhibition for the graphene between two plates. Here, we show that, in fact, this is what happens and calculate how the presence of a cavity formed by two conducting plates parallel to the suspended graphene sheet amplifies, in a non-additive manner, the inhibition of the logarithmic renormalization of the Fermi velocity. In the limits of a single plate and no plates, our formulas recover those found in the literature.This work was partially supported by the following Brazilian Agencies: Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), and Fundacao de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ). E. C. Marino was partially supported by CNPq and FAPERJ. D. T. Alves was partially supported by CAPES via Programa Estagio Senior no Exterior - Processo 88881.119705/2016-01, by CNPq via Processos 461826/2014-3 (Edital Universal) and 311920/2014-4 (Bolsa de Produtividade em Pesquisa), and also thanks Jaime Santos, Mikhail I. Vasilevskiy, Nuno M. R. Peres and Yuliy Bludov for useful discussions, as well as the hospitality of the Centro de Fisica, Universidade do Minho, Braga - Portugal. V. S. Alves acknowledges CNPq for support through Bolsa de Produtividade em Pesquisa n. 312654/2017-0. The authors also thank Ygor P. Silva for useful comments

From Compact Discs to Streaming: A Comparison of Eras within the Brazilian Market

The music industry has undergone many changes in the last few decades, notably since vinyl, cassettes and compact discs faded away as streaming platforms took the world by storm. This Digital evolution has made huge volumes of data about music consumption available. Based on such data, we perform cross-era comparisons between Physical and Digital media within the music market in Brazil. First, we build artists' success time series to detect and characterize hot streak periods, defined as high-impact bursts that occur in sequence, in both eras. Then, we identify groups of artists with distinct success levels by applying a cluster analysis based on hot streaks' features. We find the same clusters for both Physical and Digital eras: Spike Hit Artists, Big Hit Artists, and Top Hit Artists. Our results reveal significant changes in the music industry dynamics over the years by identifying the core of each era

Physical characteristics of guava (Psidium guajava L.) submitted to hot water treatment

Post harvest losses of fruits and vegetables could be reduced if appropriate practices after the harvest until its commercialization are adopted. For this, not only knowledge of the physiological processes of the product is necessary, but also an adequate infrastructure and distribution logistic. The indiscriminate use of chemical products for eradication of plagues and diseases in the cultivation and also in the post harvest period is being substituted successfully by methods that do not cause harm to human beings or to the environment, reasons for which physical treatments (application of heat, cold or ionized radiation) are being intensively investigated. Some parameters related to physical and physiologic quality of the guava Pedro Sato, were determined in this research, after complete immersion of the fruits in hot water at a temperature of 47 °C during 6 min, and stored at 8 and 22 °C, with medium relative humidity equal to 89%. It was observed that the hot water treatment, in a general way, promoted retardation in the mass loss and the firmness during the storage period, but did not cause a climacteric ascension in the production of CO2 and ethylene.As perdas pós-colheita de frutas e hortaliças podem ser reduzidas se práticas adequadas desde a colheita até a sua comercialização forem adotadas, para tanto é necessário não só o conhecimento dos processos fisiológicos do produto, mas também uma infra-estrutura e logística de distribuição adequada. O uso indiscriminado de produtos químicos para erradicação de pragas e doenças na lavoura e no período pós-colheita está sendo substituído com sucesso por métodos que não causem danos ao homem nem ao meio ambiente, razão por que tratamentos físicos (aplicação de calor, frio ou radiação ionizante) estão sendo amplamente pesquisados. Foram avaliados, neste trabalho, alguns parâmetros relacionados à qualidade física e fisiológica de goiabas Pedro Sato, após a imersão de frutos íntegros em água a temperatura de 47 °C, durante 6 min, e armazenadas a 8 e 22 °C, com umidade relativa média igual a 89%. Observou-se de maneira geral, que o tratamento hidrotérmico proposto, promoveu retardamento na perda de massa e na firmeza da polpa durante o período de armazenamento mas não se constatou ascensão climatérica na produção de CO2 e etileno.40841

Incidence and risk factors for Preeclampsia in a cohort of healthy nulliparous pregnant women: a nested case-control study

The objective of this study is to determine the incidence, socio-demographic and clinical risk factors for preeclampsia and associated maternal and perinatal adverse outcomes. This is a nested case-control derived from the multicentre cohort study Preterm SAMBA, in five different centres in Brazil, with nulliparous healthy pregnant women. Clinical data were prospectively collected, and risk factors were assessed comparatively between PE cases and controls using risk ratio (RR) (95% CI) plus multivariate analysis. Complete data were available for 1,165 participants. The incidence of preeclampsia was 7.5%. Body mass index determined at the first medical visit and diastolic blood pressure over 75 mmHg at 20 weeks of gestation were independently associated with the occurrence of preeclampsia. Women with preeclampsia sustained a higher incidence of adverse maternal outcomes, including C-section (3.5 fold), preterm birth below 34 weeks of gestation (3.9 fold) and hospital stay longer than 5 days (5.8 fold) than controls. They also had worse perinatal outcomes, including lower birthweight (a mean 379 g lower), small for gestational age babies (RR 2.45 [1.52-3.95]), 5-minute Apgar score less than 7 (RR 2.11 [1.03-4.29]), NICU admission (RR 3.34 [1.61-6.9]) and Neonatal Near Miss (3.65 [1.78-7.49]). Weight gain rate per week, obesity and diastolic blood pressure equal to or higher than 75 mmHg at 20 weeks of gestation were shown to be associated with preeclampsia. Preeclampsia also led to a higher number of C-sections and prolonged hospital admission, in addition to worse neonatal outcomes9CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ401636/2013-5Bill and Melinda Gates FoundationGates Foundation [OPP1107597]; CNPqNational Council for Scientific and Technological Development (CNPq) [401636/2013-5