227 research outputs found

    Higher Order Statistics in a mmWave Propagation Environment

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    (c) 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.[EN] A thorough measurement campaign in an indoor environment at the millimeter-wave band is carried out with an aim at characterizing the short-term fading channel in terms of its higher-order statistics. The measurements are conducted in a variety of scenarios, with frequencies ranging from 55 to 65 GHz, in line-of-sight and non-line-of-sight conditions, and combinations of horizontal and vertical polarizations at both the transmitter and the receiver. A number of fading models are tested, namely Rayleigh, Rice, Nakagami-m, alpha-mu, kappa-mu, eta-mu, and alpha-eta-kappa-mu. The main second-order statistics under analysis are the level crossing rate (LCR) and average fade duration (AFD) both given per distance unit. From the experimental data, the parameters of these statistics are estimated, and the corresponding curves of the theoretical models are compared with the empirical ones and the best model is selected. Additionally, the study of the very general distribution, namely alpha-eta-kappa-mu, is advanced, in which new expressions for time-/distance-domain LCR and Al-ll are derived using an envelope-based approach. Such an approach leads to integral-form formulations with much less computational complexity and computes rapidly compared with the already existing ones presented elsewhere, also given in the integral form. Furthermore, a series of expansion expression for the alpha-eta-kappa-mu time-/distance-domain LCR is then derived that improves even further the computational time.This work was supported in part by the Conselho Nacional de Desenvolvimento Cientico e Tecnologico (CNPq) under Grant 304248/2014-2 and Grant 308365/2017-8, in part by the Rede Nacional de Ensino e Pesquisa (RNP), with resources from Ministerio da Ciencia, Tecnologia, Inovacoes e Comunicacoes (MCTIC), through the Radiocommunication Reference Center [Centro de Referencia em Radiocomunicacoes (CRR)] Project of the National Institute of Telecommunications [Instituto Nacional de Telecomunicacoes (INATEL)], Brazil, under Grant 01250.075413/2018-04, and in part by the Ministerio de Economia, Industria y Competitividad of the Spanish Government through the Agencia Estatal de Investigacion (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER) under Project TEC2017-86779-C2-2-R.Dos Anjos, AA.; Rufino-Marins, TR.; Nogueira Da Silva, CR.; Rodrigo Peñarrocha, VM.; Rubio Arjona, L.; Reig, J.; Amaral De Souza, RA.... (2019). Higher Order Statistics in a mmWave Propagation Environment. IEEE Access. 7:103876-103892. https://doi.org/10.1109/ACCESS.2019.2930931S103876103892

    Atividade antioxidante total em frutos de diferentes genótipos de umbuzeiro oriundos de Petrolina, PE.

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    Este trabalho teve como objetivo avaliar a atividade antioxidante total dos extratos fenólicos obtidos de frutos de 32 genótipos de umbuzeiro através de dois métodos: ABTS e Sistema l3-caroteno/ácido linoléico

    Levantamento preliminar da fauna edáfica em remanescente florestal, no município de Plácido de Castro, AC.

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    O objetivo deste trabalho foi realizar um levantamento da fauna edáfica em um remanescente florestal, no município de Plácido de Castro, AC. A transição de uma floresta para uma pastagem, apresenta redução na diversidade de espécies. Dentre os organismos, os insetos são considerados bons indicadores ambientais, devido à grande diversidade de espécies e habitat, além da sua importância nos processos biológicos dos ecossistemas naturais

    Spirometry reference values in the Brazilian population

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    Abstract The aim of the present study was to provide new spirometry reference equations in a sample of the Brazilian population for the following parameters: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV 1 ), FEV 1 /FVC ratio, peak of expiratory flow (PEF), forced expiratory flow at 50% (FEF 50% ) , 75% average vital capacity (FEF 25-75% ), and average forced expiratory flow time (FEFT). This was a prospective study using results from chest radiographs, electrocardiograms, and questionnaires to investigate the participants' respiratory symptoms, sedentarism, and comorbidities (Charlson comorbidity index). From December 2010 to July 2014, individuals were randomly selected from various locations in the state of Rio de Janeiro. All individuals were examined by a single technician in the morning at the laboratory, and performed the spirometry with the same spirometer. Spirometry values were tabulated for the creation of three equation models: linear regression, logarithmic regression, and logarithms through a method that incorporates the lambda, median, and coefficient of variation (LMS method). Initially, 7003 individuals from both genders were contacted, and 454 were recruited. The data from the new equations were compared with one Brazilian and eight international equations, resulting in a high correlation (r40.9). The values derived from the LMS method and linear regression were very similar (P40.5), and both could be used to acquire the reference values for Brazilian spirometry. Data derived from the equations of this study were different from the current Brazilian equation, which could be justified by the different method used

    Fluid as a critical biomarker in neovascular age-related macular degeneration management: literature review and consensus recommendations.

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    Current guidelines on the management of patients with neovascular age-related macular degeneration (nAMD) lack clear recommendations on the interpretation of fluid as seen on optical coherence tomography (OCT) imaging and the incorporation of this information into an ongoing disease treatment strategy. Our objective was to review current guidelines and scientific evidence on the role of fluid as a biomarker in the management of nAMD, and develop a clinically oriented, practical algorithm for diagnosis and management based on a consensus of expert European retinal specialists. PubMed was searched for articles published since 2006 relating to the role of fluid in nAMD. A total of 654 publications were screened for relevance and 66 publications were included for review. Of these, 14 were treatment guidelines, consensus statements and systematic reviews or meta-analyses, in which OCT was consistently recommended as an important tool in the initial diagnosis and ongoing management of nAMD. However, few guidelines distinguished between types of fluid when providing recommendations. A total of 52 publications reported primary evidence from clinical trials, studies, and chart reviews. Observations from these were sometimes inconsistent, but trends were observed with regard to features reported as being predictive of visual outcomes. Based on these findings, diagnostic recommendations and a treatment algorithm based on a treat-and-extend (T&E) regimen were developed. These provide guidance on the diagnosis of nAMD as well as a simple treatment pathway based on the T&E regimen, with treatment decisions made according to the observations of fluid as a critical biomarker for disease activity

    Brincoquímica: Uma Ferramenta Lúdico-Pedagógica para o Ensino de Química Orgânica

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    Os jogos proporcionam uma metodologia inovadora e atraente para ensinar de forma mais prazerosa e interessante, já que a falta de motivação é a principal causa do desinteresse dos estudantes, quase sempre acarretada pela metodologia utilizada pelo professor, ao repassar osconteúdos. Logo este trabalho tem o objetivo de relatar atividades lúdicas no Ensino de Química, com alunos da 3ª série do Ensino Médio de uma escola pública do município de Barreiros no estado da Pernambuco. Os resultados indicaram que a maioria dos alunos gostou da estratégia, pois esta tornou a aula mais interessante e dinâmica, contribuiu para o trabalho em equipe, promoveu estímulo ao estudo, despertou a curiosidade e motivou-os a participarem da construção do próprio conhecimento

    Ensinagem Significativa do Conceito de Haletos Orgânicos por Meio de Mapas Conceituais.

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    Este trabalho objetiva construir junto aos estudantes do terceiro ano do ensino médio, ações que propiciem experiências significativas, para que os mesmos possam construir conceitos científicos na disciplina Química. A pesquisa foi realizada com duas turmas do Ensino Médio de duas escolas públicas do estado de Pernambuco, no período de abril a agosto de 2011, utilizando mapas conceituais comoferramenta didática, o que possibilitou aos estudantes a vivência com os processos de construção dos conceitos e explanação dos seus significados, referente ao conteúdo haletos orgânicos a partir da temática, agrotóxicos versus impactos ambientais. Na elaboração dos mapas os estudantes empregaram como palavras de ligação, frases e definições. Inicialmente os estudantes relutam ao exercício, pois não tinham o costume de fazer uso desta técnica, porém ao final do trabalho foi perceptível o ganho cognitivodos estudantes
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