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au:Cerqueira Jr., A.

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A Novel Dielectric Slab Antenna Based on Microstrip-Franklin Excitation for mm-Waves
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Boas, E. C. Vilas

; Alves, A. A. C.

; Ribeiro, J. A. J.

; Cerqueira S. Jr., Arismar

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

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jun 2020, Volume 19 N. 2 Pages 203 - 213

Abstract: En | Text: En | PDF: En

Abstract This work reports the development of a novel dielectric slab antenna based on microstrip-Franklin radiators, which enables efficient impedance matching among microstrip lines, substrate and air. The proposed antenna has been designed and numerically evaluated using ANSYS HFSS®. Its directivity ranges from 6.67 to 16.24 dB, as its length is increased from 19.9 to 170 mm. The 80 mm-length antenna prototype provides 11.14% fractional bandwidth (27.96 - 31.26 GHz) and 10.5 dBi gain at 30 GHz. The proposed antenna has been manufactured and applied to an indoor digital wireless communication link to provide 6 Gb/s throughput using 64-QAM modulation format, aiming 5G applications.

https://doi.org/10.1590/2179-10742020v19i2822

Prognostic Value of NT-proBNP versus Killip Classification in Patients with Acute Coronary Syndromes
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Souza, Thiago M. B.

; Cerqueira Jr., Antônio Maurício S.

; Suerdieck, Jessica G.

; Sá, Nicole C. de

; Sodré, Gabriella S.

; Correia, Vitor C. A.

; Lacerda, Yasmin F.

; Fonseca, Leticia L.

; Noya-Rabelo, Marcia M.

; Correia, Luis C. L.

Arquivos Brasileiros de Cardiologia

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apr 2020, Volume 114 N. 4 Pages 666 - 672

Abstract: En Pt | Text: En Pt | PDF: En | PDF: Pt

Abstract Background: Plasma levels of brain natriuretic peptides have better diagnostic accuracy compared to clinical-radiologic judgment for acute heart failure. In acute coronary syndromes (ACS), the prognostic value of acute heart failure is incorporated into predictive models through Killip classification. It is not established whether NT-proBNP could increment prognostic prediction. Objective: To evaluate whether NT-proBNP, as a measure of left ventricular dysfunction, improves the in-hospital prognostic value of the GRACE score in ACS. Methods: Patients admitted due to acute chest pain, with electrocardiogram and/or troponin criteria for ACS were included in the study. The plasma level of NT-proBNP was measured at hospital admission and the primary endpoint was defined as cardiovascular death during hospitalization. P-value < 0.05 was considered as significant. Results: Among 352 patients studied, cardiovascular mortality was 4.8%. The predictive value of NT-proBNP for cardiovascular death was shown by a C-statistic of 0.78 (95% CI = 0.65-0.90). After adjustment for the GRACE model subtracted by Killip variable, NT-proBNP remained independently associated with cardiovascular death (p = 0.015). However, discrimination by the GRACE-BNP logistic model (C-statistics = 0.83; 95%CI = 0.69-0.97) was not superior to the traditional GRACE Score with Killip (C-statistic = 0.82; 95%CI = 0.68-0.97). The GRACE-BNP model did not provide improvement in the classification of patients to high risk by the GRACE Score (net reclassification index = - 0.15; p = 0.14). Conclusion: Despite the statistical association with cardiovascular death, there was no evidence that NT-proBNP increments the prognostic value of GRACE score in ACS.

Resumo Fundamento: Os níveis plasmáticos de peptídeos natriuréticos cerebrais têm melhor precisão diagnóstica em comparação com a avaliação clínico-radiológica para insuficiência cardíaca aguda. Nas síndromes coronárias agudas (SCA), o valor prognóstico da insuficiência cardíaca aguda é incorporado nos modelos preditivos através da classificação de Killip. Não está estabelecido se o NT-proBNP poderia aumentar a previsão prognóstica. Objetivo: Avaliar se o NT-proBNP, como medida da disfunção ventricular esquerda, melhora o valor prognóstico intra-hospitalar do escore GRACE na SCA. Métodos: Foram incluídos no estudo pacientes admitidos por dor torácica aguda, com eletrocardiograma e/ou critérios de troponina para SCA. O nível plasmático de NT-proBNP foi medido no momento da admissão hospitalar e o desfecho primário foi definido como morte cardiovascular durante a hospitalização. Foi considerado significativo o valor de p < 0,05. Resultados: A mortalidade cardiovascular entre os 352 pacientes estudados foi de 4,8%. O valor preditivo do NT-proBNP para morte cardiovascular foi mostrado por uma estatística C de 0,78 (IC 95% = 0,65-0,90). Após o ajuste para o modelo GRACE subtraído pela variável Killip, o NT-proBNP permaneceu independentemente associado à morte cardiovascular (p = 0,015). No entanto, a discriminação pelo modelo logístico GRACE-BNP (estatística C = 0,83; IC 95% = 0,69-0,97) não foi superior ao escore GRACE tradicional com Killip (estatística C = 0,82; IC 95% = 0,68-0,97). O modelo GRACE-BNP não proporcionou melhora na classificação dos pacientes de alto risco pelo Escore GRACE (índice líquido de reclassificação = - 0,15; p = 0,14). Conclusão: Apesar da associação estatística com a morte cardiovascular, não houve evidências de que o NT-proBNP aumente o valor prognóstico do escore GRACE na SCA.

https://doi.org/10.36660/abc.20180345

Dual-band System composed by a Photonics-based Radar and a Focal-Point/Cassegrain Parabolic Antenna
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Brandão, T. H.

; Filgueiras, H.R.D.

; Alves, A. A. C.

; Scotti, F.

; Melo, S.

; Bogoni, A.

; Arismar Cerqueira Jr., S.

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

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oct 2018, Volume 17 N. 4 Pages 567 - 578

Abstract: En | Text: En | PDF: En

Abstract This work reports a dual-band radar system composed of aphotonics-based transceiver and a unique dual-band antenna. The proposed antenna consists of an integration of conventional focal-point and Cassegrain parabolic antennas in the same structure, ensured by using a subreflector based on a frequency selective surface. Numerical and experimental results in terms of the antenna reflection coefficient, radiation pattern and gain are reported with excellent agreement over both frequency ranges. The innovative dual-band photonics-based radar transceiver operates simultaneously in the S- and X-bands. The radar system has been properlyvalidated by multiple detections of helicopters and airplanes in real conditions.

https://doi.org/10.1590/2179-10742018v17i41545

Material Characterization and Propagation Analysis of mm-Waves Indoor Networks
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Fagiani, A.

; Vogel, M.

; Cerqueira S. Jr., Arismar

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

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oct 2018, Volume 17 N. 4 Pages 628 - 637

Abstract: En | Text: En | PDF: En

Abstract This paper reports detailed propagation analyses of mm-wave indoor networks based numerical simulations of the wireless coverage and measurements of the propagation coefficient at 28 and 38 GHz. Additionally, material characterization of typical buildings materials used in constructions are presented, including: common brick (with and without electrical installations); plaster walls; glazing, Eucatex panels; wooden doors. The computational simulations have been performed using Altair WinProp™ software in order to predict path loss in LOS (Line-of-Sight) and NLOS (Non-Line-of-Sight) environments. The obtained results contributes to the planning of the fifth Generation of mobile communications networks (5G), operating in mm-waves.

https://doi.org/10.1590/2179-10742018v17i41548

Brazilian legislation on genetic heritage harms Biodiversity Convention goals and threatens basic biology research and education
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ALVES, RUY JOSÉ V.

; WEKSLER, MARCELO

; OLIVEIRA, JOÃO A.

; BUCKUP, PAULO A.

; POMBAL JR., JOSÉ P.

; SANTANA, HÉLCIO R.G.

; PERACCHI, ADRIANO LÚCIO

; KELLNER, ALEXANDER W.A.

; ALEIXO, ALEXANDRE

; LANGGUTH, ALFREDO

; ALMEIDA, ALZIRA MARIA P. DE

; ALBERNAZ, ANA LUISA

; RIBAS, CAMILA C.

; ZILBERBERG, CARLA

; GRELLE, CARLOS EDUARDO V.

; ROCHA, CARLOS F.D.

; LAMAS, CARLOS JOSÉ E.

; HADDAD, CÉLIO F.B.

; BONVICINO, CIBELE R.

; PRADO, CYNTHIA P.A.

; LIMA, DANIELA O. DE

; ROSSA-FERES, DENISE C.

; SANTOS, FABRÍCIO R. DOS

; SALIMENA, FÁTIMA REGINA G.

; PERINI, FERNANDO A.

; BOCKMANN, FLÁVIO A.

; FRANCO, FRANCISCO LUÍS

; GIUDICE, GISELE M.L. DEL

; COLLI, GUARINO R.

; VIEIRA, IMA CÉLIA G.

; MARINHO-FILHO, JADER

; WERNECK, JANE M.C.F.

; SANTOS, JORGE A.D. DOS

; NASCIMENTO, JORGE LUIZ DO

; NESSIMIAN, JORGE LUIZ

; CORDEIRO, JOSÉ LUIS P.

; CLARO, KLEBER DEL

; SALLES, LEANDRO O.

; CASATTI, LILIAN

; PY-DANIEL, LUCIA HELENA R.

; SILVEIRA, LUÍS FÁBIO

; TOLEDO, LUÍS FELIPE

; OLIVEIRA, LUIZ F. DE

; MALABARBA, LUIZ ROBERTO

; SILVA, MARCELO D. DA

; COURI, MÁRCIA S.

; MARTINS, MÁRCIO

; TAVARES, MARCOS D.S.

; SOBRAL, MARCOS EDUARDO G.

; VIEIRA, MARCUS VINÍCIUS

; OLIVEIRA, MARIA DE LOURDES A.

; PINNA, MÁRIO DE

; HOPKINS, MICHAEL J.G.

; SOLÉ, MIRCO

; MENEZES, NAÉRCIO A.

; PASSOS, PAULO

; D’ANDREA, PAULO SERGIO

; PINTO, PEDRO C.E.A.

; VIANA, PEDRO L.

; TOLEDO, PETER M.

; REIS, ROBERTO E.

; VILELA, ROBERTO

; BASTOS, ROGÉRIO P.

; COLLEVATTI, ROSANE G.

; CERQUEIRA, RUI

; CASTROVIEJO-FISHER, SANTIAGO

; CARAMASCHI, ULISSES

Anais da Academia Brasileira de Ciências

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apr 2018, Volume 90 N. 2 Pages 1279 - 1284

Abstract: En | Text: En | PDF: En

https://doi.org/10.1590/0001-3765201820180460

A low-profile and ultra-wideband printed antenna with a 176% bandwidth
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Santos, R. A.

; Cerqueira S. Jr., Arismar

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

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mar 2017, Volume 16 N. 1 Pages 59 - 69

Abstract: En | Text: En | PDF: En

Abstract This work reports the development of a simple, low-profile and ultra-wideband printed antenna. The proposed antenna is based on a truncated ground plane and an impedance matching structure formed by a round junction and two chamfers; these modifications significantly increase the antenna frequency bandwidth compared to conventional microstrip antennas and ultra-wideband printed monopoles published in literature. An antenna prototype was fabricated using an Arlon DiClad 880 substrate with an electrical permittivity of 2.2. A bandwidth of 176% was attained at a central frequency of 14.9 GHz (ranging from 1.79 to 28.02 GHz). Numerical simulations and experimental results of the antenna's radiation pattern are also reported and exhibit good agreement. To the best of our knowledge, this is the widest bandwidth from a printed antenna that has been published in the literature.

https://doi.org/10.1590/2179-10742017v16i1621

Electromagnetic Characterization of Aircraft Composite Materials and its Effects on the Antenna Performance
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Silva, L. G. da

; Baratta, I. A.

; Assis, R. R. de

; Bellei, L. N.

; Andrade, C. B. de

; Campici, P. P. F.

; Nunes, S. O.

; Paiva, M. C.

; Cerqueira S. Jr., Arismar

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

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mar 2017, Volume 16 N. 1 Pages 218 - 236

Abstract: En | Text: En | PDF: En

Abstract This paper presents an electromagnetic characterization of aircraft composite materials, as well as numerical and experimental analyses of its effects on the antenna performance. Two uncalibrated S-parameters characterization methods have been applied for retrieving the complex electrical permittivity in the L- and C-band, namely: Air-region method and Sample-shifted method. Dielectric constants of 4.6 and 1.84 and loss tangent of 2.0×10−2 and 6.1×10−2 have been obtained for fiberglass and honeycomb composite materials, respectively. A 3.0-meters prototype of an Embraer light jet aircraft dorsal fin was fabricated and used in the experiments in a semi-anechoic chamber in order to evaluate the impact of installing aeronautical VHF and L-band antennas on a fuselage made of composite materials.

https://doi.org/10.1590/2179-10742017v16i1884

Desempenho físico-químico de filmes hidrofóbicos de AlN e de Ti nanoestruturado crescidos por plasma frio sobre superfícies de isoladores cerâmicos de porcelana tipo pino
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Mazur, M. M.

; Bragança, M. D´O. G. P.

; Portella, K. F.

; Ribeiro Jr., S.

; de Melo, J. S. S.

; Cerqueira, D. P.

; Pianaro, S. A.

Cerâmica

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mar 2016, Volume 62 N. 361 Pages 60 - 70

Abstract: En Pt | Text: En Pt | PDF: En | PDF: Pt

Abstract The mechanical strength and the dielectric properties of ceramic insulators are essential properties to support the electricity distribution networks. However, both the moisture and the pollutant content in the atmosphere may become harmful and cause failures in the power supply by increasing its electrical current leakage. The insulating glazing has high affinity with the resulting water from the interaction of the glass surface with atmosphere. In this study, the deposition of aluminum nitride films was carried out on the glazed samples of ceramic electrical insulators, via pulsed DC magnetron sputtering plasma, and with a mixture of argon and nitrogen gas and Ti on pin type insulators for 15 kV voltage class. The morphology of the films and the performance of insulators were measured by SEM-FEG/EDS, AFM, maximum RMS leakage current and degree of hydrophobicity. The performance of deposited films by the degree of hydrophobicity measured in samples reduced from CM6 to CM4 with AlN, and CM7 to CM3 with Ti layer. The maximum RMS leakage current measured with and without the insulating film based on nanometric Ti was higher in devices without the pr otection, reaching measured values of 5 mA and with shutdown of computerized measuring system (after 3 days in Sauípe and 3 months in Pituba) as a consequence of having overcome the short circuit withdrawal period laid down in software (surges exceeding 300 mA). With the deposition of the films in 7 insulators, changes in two of these, with peaks of maximum leakage current achieving 2.4 mA, in the field were observed. Most insulators analyzed had the variations in RMS leakage current between 0.2 and 2 mA in the measurement period, in adverse conditions of weather (rain and differ ent wind speeds).

Resumo A resistência mecânica e a propriedade dielétrica de isoladores cerâmicos são características fundamentais para o suporte das redes de distribuição de energia elétrica. Porém, tanto a umidade quanto o teor de poluentes na atmosfera podem vir a ser prejudiciais e causar falhas na entrega de energia por elevação da sua corrente elétrica de fuga. O vidrado do isolador tem grande afinidade com a água resultante da interação da superfície do vidro com a atmosfera. No presente trabalho, foi realizada a deposição de filmes de nitreto de alumínio sobre o vidrado de amostras de isoladores elétricos cerâmicos, via plasma "magnetron sputtering" pulsado, de corrente contínua, e com uma mistura dos gases argônio e nitrogênio e de Ti sobre isoladores tipo pino para classes de tensão de 15 kV. A morfologia dos filmes e o desempenho dos isoladores foram medidos por MEV-FEG/EDS, AFM, máxima corrente de fuga RMS e grau de hidrofobicidade. O comportamento dos filmes depositados medido pelo grau de hidrofobicidade reduziu nas amostras de CM6 para CM4, com AlN, e de CM7 para CM3 quando foi depositado o Ti. A máxima corrente de fuga RMS medida nos isoladores sem e com filme nanométrico à base de Ti foi superior nos dispositivos sem a proteção, alcançando valores medidos de 5 mA e com desligamento do sistema computadorizado de medida (após 3 dias em Sauípe e 3 meses em Pituba) em consequência desta ter superado o intervalo de segurança de curto circuito estabelecido nos dispositivos eletrônicos de proteção (surtos superiores a 300 mA). Com a deposição dos filmes em 7 isoladores, foram verificadas alterações de comportamento em dois destes, com picos de máxima corrente de fuga atingindo 2,4 mA no campo. A maioria dos isoladores analisados teve como variações de correntes de fuga RMS, no período de medida, entre 0,2 e 2 mA, em condições adversas de clima (com chuva e diferentes velocidades de vento).

https://doi.org/10.1590/0366-69132016623611928

Coupling constants of D*DsK and Ds*DK processes
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Bracco, M. E.

; Lozéa, A.

; Cerqueira Jr., A.

; Chiapparini, M.

; Nielsen, M.

Brazilian Journal of Physics

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mar 2007, Volume 37 N. 1a Pages 59 - 62

Abstract: En | Text: En | PDF: En

We calculate the coupling constants of D*Ds K and Ds*DK vertices using the QCD sum rules technique. We compare our results with results obtained in the limit of SU(4) symmetry and we found that the symmetry is broken at the order of 40%.

https://doi.org/10.1590/S0103-97332007000100019

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