35 resultados para Caesium 137, standard deviation


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Objetivou-se, neste trabalho, determinar os balanços de radiação e energia da cultura de alface (Lactuca sativa, L. cv. Verônica) em estufa de polietileno. O experimento foi realizado em uma estufa tipo túnel alto com cobertura de polietileno (100 mim de espessura) e em uma área externa, ambas com 35 m². Durante o ciclo da cultura, foram monitoradas as radiações global e refletida, saldo de radiação, fluxo de calor no solo e temperatura do ar (seca e úmida) nos dois meios. Utilizou-se um Datalogger que operou na freqüência de 1 Hz, armazenando médias de cinco minutos. A partir das integrações diárias das irradiâncias global (K¯) e refletida (K­), verificou-se que a transmissividade média da radiação global (K¯in / K¯ex) foi aproximadamente constante, em torno de 79,59%, enquanto a razão das radiações refletidas (K­in / K­ex) foi igual a 69,21% com coeficiente de variação de 8,47%. As curvas normalizadas do saldo de radiação de ondas curtas em relação à radiação global (K* / K¯), nos dois meios, mostraram ser aproximadamente constantes no início do ciclo e decrescentes no final. A relação (Rn/ K¯) foi maior no meio externo, em torno de 12%, a partir da fase em que a superfície verde da cultura cobriu o solo. O balanço médio (L*) de radiação de ondas longas foi maior no exterior, em torno de 50%. O balanço de energia, estimado em termos de fluxos verticais, mostrou, em média, que: no exterior, 83,07% do saldo de radiação foi convertido em calor latente (LE), 18,00% em fluxo de calor no solo (G) e 9,96% em calor sensível (H), enquanto que, no interior da estufa, 58,71% do saldo de radiação foi convertido em LE, 42,68% em H e 28,79% em G.

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O experimento foi instalado com o objetivo de estudar o desempenho agronômico de cultivares de bananeira Prata-anã e Maçã, na região de São Manuel-SP. Foram avaliadas as seguintes características de desenvolvimento, no primeiro ciclo de produção: número de dias do plantio à floração e da mesma à colheita, número de rebentos (filhos) emitidos até o surgimento da inflorescência e na época da colheita, número de folhas ativas na época do aparecimento da inflorescência e da colheita, e características de rendimento, como peso médio do cacho, ráquis, penca e fruto, número médio de frutos por penca e cacho, comprimento e diâmetro médio dos frutos. Também foi avaliada a incidência de pragas e doenças. Foi empregado o delineamento inteiramente casualizado, com 2 tratamentos, 15 repetições e 5 plantas úteis por parcela experimental. As duas cultivares foram caracterizadas pelos valores das estatísticas descritivas, média e desvio-padrão, para as características de interesse no experimento. Foram estabelecidas possíveis correlações entre medidas de desenvolvimento e produção. As duas cultivares apresentaram ciclo do plantio até a colheita de 574 dias para 'Prata-anã' e 567 dias para 'Maçã', sendo que o ciclo produtivo foi maior na 'Prata-anã'. Não houve problemas de pragas e doenças em todo o ciclo de produção, nas duas cultivares avaliadas.

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Foram avaliados os perfis de distribuição volumétrica das pontas de pulverização de jato plano Extended Range XR 8004, Teejet TP 8004 e TwinJet TJ60-8004, em mesa de teste construída segundo a norma ISO 5.682-1:1996, sendo as pontas de pulverização posicionadas a 30, 40 e 50 cm de altura da mesa coletora, submetidas à pressão de 200 e 300 kPa, e posicionadas com ângulos de 30 e 45º nos sentidos horário e anti-horário e na posição vertical (0º). As pontas TJ60-8004 foram analisadas nas mesmas alturas, porém somente na posição vertical. Avaliaram-se 10 unidades de cada tipo de ponta, instaladas isoladamente na mesa. A distribuição média do volume pulverizado, coletado nas provetas, foi inserida em programa computacional, que permitiu a simulação do perfil de distribuição de uma barra pulverizadora com 24 bicos, em espaçamentos variáveis, obtendo-se ao final o coeficiente de variação, o desvio-padrão e a média do volume. Os resultados mostraram que a uniformidade de distribuição é menos influenciada pela variação da altura da barra quando o espaçamento entre bicos é reduzido e que há necessidade de adequação do espaçamento quando se utiliza ângulo na barra pulverizadora.

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Ionospheric scintillations are caused by time-varying electron density irregularities in the ionosphere, occurring more often at equatorial and high latitudes. This paper focuses exclusively on experiments undertaken in Europe, at geographic latitudes between similar to 50 degrees N and similar to 80 degrees N, where a network of GPS receivers capable of monitoring Total Electron Content and ionospheric scintillation parameters was deployed. The widely used ionospheric scintillation indices S4 and sigma(phi) represent a practical measure of the intensity of amplitude and phase scintillation affecting GNSS receivers. However, they do not provide sufficient information regarding the actual tracking errors that degrade GNSS receiver performance. Suitable receiver tracking models, sensitive to ionospheric scintillation, allow the computation of the variance of the output error of the receiver PLL (Phase Locked Loop) and DLL (Delay Locked Loop), which expresses the quality of the range measurements used by the receiver to calculate user position. The ability of such models of incorporating phase and amplitude scintillation effects into the variance of these tracking errors underpins our proposed method of applying relative weights to measurements from different satellites. That gives the least squares stochastic model used for position computation a more realistic representation, vis-a-vis the otherwise 'equal weights' model. For pseudorange processing, relative weights were computed, so that a 'scintillation-mitigated' solution could be performed and compared to the (non-mitigated) 'equal weights' solution. An improvement between 17 and 38% in height accuracy was achieved when an epoch by epoch differential solution was computed over baselines ranging from 1 to 750 km. The method was then compared with alternative approaches that can be used to improve the least squares stochastic model such as weighting according to satellite elevation angle and by the inverse of the square of the standard deviation of the code/carrier divergence (sigma CCDiv). The influence of multipath effects on the proposed mitigation approach is also discussed. With the use of high rate scintillation data in addition to the scintillation indices a carrier phase based mitigated solution was also implemented and compared with the conventional solution. During a period of occurrence of high phase scintillation it was observed that problems related to ambiguity resolution can be reduced by the use of the proposed mitigated solution.

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Embora a análise no domínio da freqüência do sinal eletromiográfico (EMG) seja empregada na caracterização do processo de fadiga muscular localizada, sua aplicação, especificamente a da freqüência mediana (Fmed), é pouco explorada no âmbito esportivo. O objetivo do presente estudo foi verificar a viabilidade da aplicação do sinal EMG, através de sua análise no domínio da freqüência, como parâmetro para determinação e diferenciação no comportamento da fadiga muscular localizada. Dois grupos de sujeitos, um caracterizado como atletas (n =12) e outro como sedentários (n =12), foram submetidos a análises baseadas em procedimentos executados em três diferentes situações experimentais, todos envolvendo a modalidade de exercício isométrico: i) teste máximo para determinação da contração isométrica voluntária máxima (CIVM); ii) teste de fadiga, sustentado por 35 seg. a 80% da CIVM; iii) teste de recuperação, sustentado por 10 seg. a 80% da CIVM; neste ultimo foi monitorado o comportamento da Fmed nos três primeiros (Fmedi) e três últimos segundos (Fmedf) do sinal EMG no músculo tibial anterior durante o teste de fadiga. Durante os 10 segundos do teste de recuperação foi calculada a Fmed referente a todo o período (Fmedr). parâmetro utilizado no cálculo do índice de recuperação muscular (IRM). Os resultados apontam que a Fmedf apresentou valor menor em relação à Fmedi em ambos os grupos (p < 0,05). Quando comparado com o grupo de sedentários, o grupo de atletas apresentou valores maiores de Fmedi e Fmedf (p < 0,05). O valor médio e desvio-padrão do IRM para o grupo de atletas foram de 62,1% ± 28,7 e, para o grupo de sedentários, de 55,2% ± 27,8 (p > 0,05). Dessa forma, os resultados apresentados neste estudo permitem inferir a viabilidade na aplicação de parâmetros no domínio da freqüência do sinal EMG para a determinação e diferenciação do comportamento da fadiga muscular localizada.

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Background and objectives: The efficiency of mucociliary transport may vary in different conditions, such as in exposure to harmful particles of the cigarette smoke. The present study evaluated the acute and short term effects of smoking on nasal mucociliary clearance in current smokers by the quantification of the Saccharin Transit Time (STT), and to investigate its correlation with the history of tobacco consumption.Methods: Nineteen current smokers (11 men, 51 +/- 16 years; BMI 23 +/- 9 kg/m(2), 27 +/- 11 cigarettes per day, 44 +/- 25 pack-years), entering a smoking cessation intervention program, responded to a questionnaire concerning smoking history and were submitted to lung function assessment (spirometry) and the STT test. STT was assessed immediately after smoking and 8 hours after smoking. The STT test was also performed in nineteen matched healthy non-smokers' who served as control group.Results: When compared to STT in non-smokers' (10 +/- 4 min; mean +/- standard deviation), smokers presented similar STT immediately after smoking (11 +/- 6 min; p = 0.87) and slower SIT 8 hours after smoking (16 +/- 6 min; p = 0.005 versus non-smokers' and p = 0.003 versus immediately after smoking). STT 8 hours after smoking correlated positively with age (r = 0.59; p = 0.007), cigarettes per day (r = 0.53; p = 0.02) and pack-years index (r = 0.74; p = 0.0003).Conclusions: In smokers, although the mucociliary clearance immediately after smoking is similar to non-smokers', eight hours after smoking it is reduced, and this reduction is closely related to the smoking habits. (C) 2010 Sociedade Portuguesa de Pneumologia. Published by Elsevier Espana, S.L. All rights reserved.

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Background: It was reported that autonomic nervous system function is altered in subjects with chronic obstructive pulmonary disease (COPD). We evaluated short-and long-term fractal exponents of heart rate variability (HRV) in COPD subjects.Patients and methods: We analyzed data from 30 volunteers, who were divided into two groups according to spirometric values: COPD (n = 15) and control (n = 15). For analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 30 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal] and RMSSD [root-mean square of differences]) and frequency domains (low frequency [LF], high frequency [HF], and LF/HF), and the short-and long-term fractal exponents were obtained by detrended fluctuation analysis. We considered P < 0.05 to be a significant difference.Results: COPD patients presented reduced levels of all linear exponents and decreased short-term fractal exponent (alpha-1: 0.899 +/- 0.18 versus 1.025 +/- 0.09, P = 0.026). There was no significant difference between COPD and control groups in alpha-2 and alpha-1/alpha-2 ratio.Conclusion: COPD subjects present reduced short-term fractal correlation properties of HRV, which indicates that this index can be used for risk stratification, assessment of systemic disease manifestations, and therapeutic procedures to monitor those patients.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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A sensitive, precise, and specific high-performance liquid chromatographic (HPLC) method was developed for the assay of gatifloxacin (GATX) in raw material and tablets. The method validation parameters yielded good results and included the range, linearity, precision, accuracy, specificity, and recovery. It was also found that the excipients in the commercial tablet preparation did not interfere with the assay. The HPLC separation was carried out by reversed-phase chromatography on a C18 absorbosphere column (250 x 4.6 mm id, 5 pm particle size) with a mobile phase composed of acetic acid 50/o--acetonitrile-methanol (70 + 15 + 15, v/v/v) pumped isocratically at a flow rate of 1.0 mL/min. The effluent was monitored at 287 nm. The calibration graph for GATX was linear from 4.0 to 14.0 mu g/mL. The interday and intraday precisions (relative standard deviation) were less than 1.05%.

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A sensitive, precise, and specific high-performance liquid chromatography (HPLC) method was developed for the assay of lomefloxacin (LFLX) in raw material and tablet preparations. The method validation parameters yielded good results and included the range, linearity, precision, accuracy, specificity, and recovery. It was also found that the excipients in the commercial tablet preparation did not interfere with the assay. The HPLC separation was performed on a reversed-phase Phenomenex C18 column (150 x 4.6 mm id, 5 pm particle size) with a mobile phase composed of 1% acetic acid-acetonitrile-methanol (70 + 15 + 15, v/v/v), pumped isocratically at a flow rate of 1.0 mL/min. The effluent was monitored at 280 nm. The calibration graph for LFLX was linear from 2.0 to 7.0 mg/mL. The interday and intraday precisions (relative standard deviation) were less than 1.0%. The method was applied for the quality control of commercial LFLX tablets to quantitate the drug.

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A simple, sensitive, and specific biodiffusion assay for the! antibacterial ceftazidime was developed using a strain of Staphylococcus epidermidis (ATCC 12228) as the test organism. Ceftazidime was measured in powder for injection at concentrations ranging from 100 to 400 mu g/mL. The calibration graph for ceftazidime was linear (r(2) = 1), and the method validation showed that it was precise (relative standard deviation = 0.415) and accurate. The results obtained by biodiffusion assay were statistically calculated by linear parallel model and by means of regression analysis and were verified using analysis of variance. It was concluded that the microbiological assay is satisfactory for in vitro quantification of the antibacterial activity of ceftazidime in pharmaceuticals.

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The validation of a microbiological assay, applying cylinder plate method for determination of the activity of lomefloxacin in coated tablets is described. Using a strain of Bacillus subtilis ATCC 9372 as the test organism, lomefloxacin was measured in concentrations ranging from 2.0 to 8.0 mu g/mL. The method validation showed that it is linear (r = 0.9999), precise (relative standard deviation 1.15%), and accurate (it measured the added quantities). The excipients did not interfere in the determination. It was concluded that the microbiological assay is satisfactory for quantitation of lomefloxacin in tablets.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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A new UV spectrophotometric method was developed for quantitative evaluation of ceftazidime preparations. The UV detector was set at 255 nm. Beer's law is obeyed in the concentration range of 7.0-14.0 mu g/mL. The method was found to be selective, linear, accurate, and precise in the specified ranges. Intra- and interday variability for the method were <2% relative standard deviation. Common excipients used as additives in pharmaceutical preparations do not interfere with the proposed method. This method was successfully used for quantification of ceftazidime in pure form and in pharmaceutical preparations.