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A comparative analysis of preprocessing techniques of cardiac event series for the study of heart rhythm variability using simulated signals BJMBR
Guimarães,H.N.; Santos,R.A.S..
In the present study, using noise-free simulated signals, we performed a comparative examination of several preprocessing techniques that are used to transform the cardiac event series in a regularly sampled time series, appropriate for spectral analysis of heart rhythm variability (HRV). First, a group of noise-free simulated point event series, which represents a time series of heartbeats, was generated by an integral pulse frequency modulation model. In order to evaluate the performance of the preprocessing methods, the differences between the spectra of the preprocessed simulated signals and the true spectrum (spectrum of the model input modulating signals) were surveyed by visual analysis and by contrasting merit indices. It is desired that estimated...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heart rhythm variability; Heart rate variability; Spectral analysis; Data preprocessing; Integral pulse frequency modulation model.
Ano: 1998 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000300015
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A spectral analysis of the myoelectric activity of the left colon in patients with schistosomiasis mansoni BJMBR
Ferraz,A.A.B..
The objective of the present study was to perform a spectral analysis of the electrical activity of the left colon of patients with hepatosplenic schistosomiasis. Thirty patients were studied, divided into 2 groups: group A was composed of 14 patients (9 males and 5 females) with hepatosplenic schistosomiasis and group B was composed of 16 female patients without schistosomiasis mansoni. Three pairs of electrodes were implanted in the left colon at the moment of the surgical treatment. The signals of the electric activity of the colon were captured after postoperative recovery from the ileus and fed into a computer by means of a DATAQ data collection system which identified and captured frequencies between 0.02 and 10 Hz. Data were recorded, stored and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Left colon; Electromyography; Spectral analysis; Root mean square; Intestinal motility; Schistosomiasis mansoni.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000500011
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An Analysis of Rank Ordered Data AgEcon
Paudel, Krishna P.; Poudel, Biswo N.; Dunn, Michael A.; Pandit, Mahesh.
Many methods are available to analyze rank ordered data. We used a spectral density method to analyze Formosan subterranean termite control options ranked by Louisiana homeowners. Respondents are asked to rank termite control options from the most preferred to the least preferred option. Spectral analysis results indicated that the most preferred termite control choice is a relatively cheap ($0.13 per square foot) option of liquid treatment.
Tipo: Conference Paper or Presentation Palavras-chave: FST; Rank ordered data; Spectral analysis; Research Methods/ Statistical Methods.
Ano: 2009 URL: http://purl.umn.edu/49518
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Analyse statistique de l'évolution temporelle de paramètres hydrobiologiques dans les bassins du port du Havre ArchiMer
Menesguen, Alain; Laurec, Alain.
The study of the spatial structure and temporal evolution of several hydrobiological parameters in a flooding docks system provided a good illustration for the analytical power of a methodology dealing with the statistical processing of multivariate timeseries. This technique can be characterized by prior extraction of the trends, treated separately as ordinary multivariate data, and by a consequent multi-spectral analysis of the residual signais. This procedure offers the advantage of clarifying the analysis of the major features of the phenomenon (i.e. the trends) and unmasking the subtle spatio-temporal structure through the residual signais. The application on Le Havre harbour showed a strong enrichment in nutrients and also a plausible but partial...
Tipo: Text Palavras-chave: Analyse spectrale; Désaisonnalisation; Séries temporelles multivariées; Eutrophisation; Spectral analysis; Deseasonalisation; Multivariate time-series; Nutrient enrichment.
Ano: 1984 URL: http://archimer.ifremer.fr/doc/00113/22466/20147.pdf
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Analysis of ranked ordered data when there are complete and partial ranking AgEcon
Pandit, Mahesh; Paudel, Krishna P.; Dunn, Michael A..
Many methods are available to analyze rank ordered data. We used a spectral density analysis to identify most preferred options of Formosan Subterranean Termites (FST) control as ranked by Louisiana homeowners. Respondents are asked to rank four termite control methods form the most preferred option to the least preferred option. Spectral analysis of both complete and partial ranked data indicates that the most preferred termite control choice is a relatively cheap ($0.13 per square foot) option of a Liquid treatment.
Tipo: Conference Paper or Presentation Palavras-chave: Complete and Partial ranked data; FST; Spectral analysis; Research Methods/ Statistical Methods; C65.
Ano: 2010 URL: http://purl.umn.edu/56430
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Analyzing Relationships Between Cash and Futures Dairy Markets Using Partially Overlapping Time Series AgEcon
Bozic, Marin; Fortenbery, T. Randall.
Replaced with revised version of paper 02/10/10.
Tipo: Conference Paper or Presentation Palavras-chave: Partially overlapping time series; Spectral analysis; Risk premium; Futures markets; Dairy policy; Dairy industry; Agribusiness; Agricultural and Food Policy; Agricultural Finance; Q13; Q14; Q18.
Ano: 2010 URL: http://purl.umn.edu/56545
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Assinatura espectral de cultivares de soja submetidas a diferentes níveis de disponibilidade hídrica. Repositório Alice
CRUSIOL, L. G. T.; NANNI, M. R.; FURLANETTO, R. H.; CESAR, E.; SIBALDELLI, R. N. R.; MERTZ-HENNING, L. M.; NEPOMUCENO, A. L.; NEUMAIER, N.; FARIAS, J. R. B..
bitstream/item/179612/1/Assinatura-espectral-p.293-295.pdf
Tipo: Artigo em anais de congresso (ALICE) Palavras-chave: Espectrometria; Variedade; Disponibilidade de Água; Soja; Soybeans; Plant available water; Spectral analysis.
Ano: 2018 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1093177
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Comparison of the Polar S810i monitor and the ECG for the analysis of heart rate variability in the time and frequency domains BJMBR
Vanderlei,L.C.M.; Silva,R.A.; Pastre,C.M.; Azevedo,F.M.; Godoy,M.F..
The aim of the present study was to compare heart rate variability (HRV) at rest and during exercise using a temporal series obtained with the Polar S810i monitor and a signal from a LYNX® signal conditioner (BIO EMG 1000 model) with a channel configured for the acquisition of ECG signals. Fifteen healthy subjects aged 20.9 ± 1.4 years were analyzed. The subjects remained at rest for 20 min and performed exercise for another 20 min with the workload selected to achieve 60% of submaximal heart rate. RR series were obtained for each individual with a Polar S810i instrument and with an ECG analyzed with a biological signal conditioner. The HRV indices (rMSSD, pNN50, LFnu, HFnu, and LF/HF) were calculated after signal processing and analysis. The unpaired...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heart rate variability; Autonomic nervous system; Exercise; Spectral analysis; ECG; Polar S810i monitor.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2008001000004
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Desenvolvimento de sensores nanoestruturados para análise de realçadores de sabor em água. Repositório Alice
FUKUSHIMA, K. L..
bitstream/item/199723/1/P-DISSERTACAO-Desenvolvimento-de-sensores-nanoestruturados-para-analise-de-realcadores-de-sabor-em-agua.pdf
Tipo: Tese/dissertação (ALICE) Palavras-chave: Sensores; Língua eletrônica; Realçadores; Radiação infravermelha; Análise espectral; Sensors; Enhancers; Água; Spectral analysis; Infrared radiation; Water analysis.
Ano: 2018 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1101318
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Determinação de extrato etéreo em amostras vegetais com uso de solvente sob alta pressão: avaliação do equipamento semiautomático ANKOM XT15. Infoteca-e
GALVANI, D. B.; MARTINS, T. P..
O presente trabalho foi conduzido com o objetivo de avaliar a acurácia do método AOCS Am 5-04 para determinação de extrato etéreo em amostras vegetais (teor máximo de extrato etéreo de 5%). Adicionalmente, a substituição dos sacos de filtro ANKOM XT4 por sacos confeccionados em poliéster foi avaliada, com vistas à redução do custo analítico.
Tipo: Comunicado Técnico (INFOTECA-E) Palavras-chave: Análise espectral; Gordura; Spectral analysis.
Ano: 2015 URL: http://www.infoteca.cnptia.embrapa.br/handle/doc/1016849
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Digital Soil Mapping of Soil Properties in the “Mar de Morros” Environment Using Spectral Data Rev. Bras. Ciênc. Solo
Campbell,Patrícia Morais da Matta; Fernandes Filho,Elpídio Inácio; Francelino,Márcio Rocha; Demattê,José Alexandre Melo; Pereira,Marcos Gervasio; and,Clécia Cristina Barbosa Guimarães; Pinto,Luiz Alberto da Silva Rodrigues.
ABSTRACT Quantification of soil properties is essential for better understanding of the environment and better soil management. The conventional techniques of laboratory analysis are sometimes costly and detrimental to the environment. Thus, development of new techniques for soil analysis that do not generate residues, such as spectroscopy, is increasingly necessary as a viable way to estimate a wide range of soil properties. The objective of this study was to predict the levels of organic carbon (OC), clay, and extractable phosphorus (P), from the spectral responses of soil samples in the visible and near infrared (Vis-NIR), medium infrared (MIR), and Vis-NIR-MIR using different preprocessing methods combined with five prediction models. Soil samples were...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Spectral analysis; Reflectance; Chemometrics.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832018000100314
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Distribution of the East China Sea continental shelf basins and depths of magnetic sources ArchiMer
Lin, Jing-yi; Sibuet, Jean-claude; Hsu, S.
The acoustic basement map of the East China Sea, established by the Shanghai Offshore Petroleum Bureau with all available industry seismic data, shows the existence of a 30-km-wide, 10-km-deep basin, that we named the Ho Basin. The Ho Basin belongs to a series of elongated deep basins extending over 600 km east of the Taiwan-Sinzi Ridge and flanked to the East by a ridge named the Longwan Ridge in its northern part. This new system of basin and ridge was probably formed during middle Miocene, sometimes in between rifting episodes occurring in the Taipei Basin and Okinawa Trough. It. complements the already defined system of five belts of back-arc basins and associated arc volcanic ridges in the East China Sea, which are progressively younger from the...
Tipo: Text Palavras-chave: Depth of magnetic sources; Spectral analysis; Backarc basins; East China Sea.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-1342.pdf
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Does acute hyperglycemia alter rat aortic depressor nerve function? BJMBR
Huber,D.A.; Carmo,J.M. do; Castania,J.A.; Fazan Jr,R.; Salgado,H.C..
Because it is not known where in the reflex arch, i.e., afference, central nervous system or efferences, hyperglycemia affects baroreflex function, the present study examined the effect of short-term (30 min) hyperglycemia on aortic depressor nerve function measured by a mean arterial pressure vs aortic depressor nerve activity curve, fitted by sigmoidal regression, or by cross-spectral analysis between mean arterial pressure and aortic depressor nerve activity. Anesthetized male Wistar rats received an intravenous bolus (0.25 mL) injection, followed by 30 min of infusion (1 mL/h) of 30% glucose (N = 14). Control groups received a bolus injection and infusion of 0.9% saline (N = 14), or 30% mannitol (N = 14). Glucose significantly increased both blood...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Pressoreceptors; Hyperglycemia; Arterial pressure; Spectral analysis.
Ano: 2007 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007001100017
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Efeito da temperatura da amostra na análise de fezes por infravermelhor próximo (NIR) com tecnologia de transmissão por arranjo de diodo. Repositório Alice
PRINCE, S.; BOMFIM, M. A. D.; ANGERER, J.; TEDESCHI, L. O..
Resumo: A tecnologia NIR com transmissão por arranjo diodo permite que espectros sejam obtidos em amostras fecais frescas reduzindo do tempo de análise. Entretanto, o alto teor de umidade associado à temperatura no momento da coleta dos espectros, pode afetar a precisão e acurácia das estimativas. O objetivo com este trabalho foi avaliar o efeito de quatro temperaturas (5, 10, 15 e 21oC ) das amostras fecais no momento da coleta dos espectros em equipamentos NIR com tecnologia de transmissão por arranjo de diodo. As amostras experimentais foram scaneadas e seu conteúdo em matérica pré-seca fecal (MPSF) estimado usando uma equação calibrada com espectros coletados em temperatura ambiente (21oC). Foram avaliadas a precisão e a acurácia, a distância de...
Tipo: Artigo em anais de congresso (ALICE) Palavras-chave: NIRS; FNIRS; Espectroscopia NIR; Matéria seca fecal; Análise espectral; Fecal dry matter; Infrared spectrophotometry; Spectrometry; Nutrição Animal; Espectrometria; Água; Espectrômetro; Spectral analysis.
Ano: 2012 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1104199
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ENSO AND SOYBEAN PRICES: CORRELATION WITHOUT CAUSALITY AgEcon
Letson, David; McCullough, B.D..
In this paper we seek to characterize the robustness of the ENSO/soybean price relationship and to determine whether it has practical economic content. If such a meaningful relationship exists, the implications could be profound for commodity traders and for public sector investments in climate forecasting capabilities. Also, the validity of economic evaluations of climate impacts and climate forecasts based on ENSO-price independence would come into question. Our findings suggest a relationship between interannual climate and soybean prices, although we are not able to attribute the relationship to ENSO or to say the ENSO is economically important.
Tipo: Journal Article Palavras-chave: Climate forecasting; Granger causality; Spectral analysis; SOI; SST; Resource /Energy Economics and Policy; C22; Q11.
Ano: 2001 URL: http://purl.umn.edu/15443
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Environmental noise in spawning areas: the case of Atlantic bluefin tuna (Thunnus thynnus) ArchiMer
Royer, Francois; Fromentin, Jean-marc.
This paper provides an exploratory analysis aiming to seek whether the colour of environmental noise theory could help in understanding the intriguing reproductive strategy of Atlantic bluefin tuna (BFT). A frequency-based approach based on spectral exponents, f(beta) with beta < 0, is chosen and applied on 10 biogeographical provinces covering the North Atlantic. The major BFT spawning area, i.e. the Mediterranean Sea, was the only one to display a pink power spectrum, whereas open ocean regions displayed more reddened fluctuations, i.e. greater variance at low frequencies. Environmental noise in the Mediterranean could, thus, offer more favourable characteristics on the long-term than the open ocean. The implications of these findings are discussed in...
Tipo: Text Palavras-chave: Thunnus thynnus; Spectral analysis; Spawning; Sea surface temperature; Environmental noise.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2437.pdf
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Estimation procedures affect the center of pressure frequency analysis BJMBR
Vieira,T.M.M.; Oliveira,L.F.; Nadal,J..
Even though frequency analysis of body sway is widely applied in clinical studies, the lack of standardized procedures concerning power spectrum estimation may provide unreliable descriptors. Stabilometric tests were applied to 35 subjects (20-51 years, 54-95 kg, 1.6-1.9 m) and the power spectral density function was estimated for the anterior-posterior center of pressure time series. The median frequency was compared between power spectra estimated according to signal partitioning, sampling rate, test duration, and detrending methods. The median frequency reliability for different test durations was assessed using the intraclass correlation coefficient. When increasing number of segments, shortening test duration or applying linear detrending, the median...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Center of pressure; Spectral analysis; Quiet standing; Estimators; Median frequency.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2009000700012
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Estudio del comportamiento de ondas lineales barotrópicas en la atmósfera tropical y el litoral ecuatoriano-colombiano en un período determinado OceanDocs
Martínez, R..
Usando series de tiempo de promedios diarios de presión atmosférica, temperatura ambiental, temperatura superficial y nivel medio del mar en los años 1994-1995 en cinco estaciones costeras de Ecuador y Colombia y una estación en las Islas galápagos (Ecuador) se aplicaron las técnicas del análisis espectral para determinar las oscilaciones existentes en el océano y la atmósfera. Se obtuvieron con alto niveles de coherencia, cinco modos predominantes en la atmósfera tropical: la oscilación de 37 días, muy próxima a la oscilación de Madden-Julian (1972), un modo de tres semanas con características de la " autooscilación" de 21 días, Murakami, 1974 y que es de naturaleza planetaria, una tercera oscilación de 17 días, de características muy similares a la onda...
Tipo: Journal Contribution Palavras-chave: Barotropic motion; Water waves; Spectral analysis; Time series; Oceanographic data; Fixed stations; Water temperature data; Air temperature; Atmospheric pressure; Mean sea level; Atmospheric pressure; Spectral analysis; Air temperature; Http://aims.fao.org/aos/agrovoc/c_693; Http://aims.fao.org/aos/agrovoc/c_28964; Http://aims.fao.org/aos/agrovoc/c_230.
Ano: 1998 URL: http://hdl.handle.net/1834/2199
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Heart rate recovery after exercise: relations to heart rate variability and complexity BJMBR
Javorka,M.; Zila,I.; Balhárek,T.; Javorka,K..
Physical exercise is associated with parasympathetic withdrawal and increased sympathetic activity resulting in heart rate increase. The rate of post-exercise cardiodeceleration is used as an index of cardiac vagal reactivation. Analysis of heart rate variability (HRV) and complexity can provide useful information about autonomic control of the cardiovascular system. The aim of the present study was to ascertain the association between heart rate decrease after exercise and HRV parameters. Heart rate was monitored in 17 healthy male subjects (mean age: 20 years) during the pre-exercise phase (25 min supine, 5 min standing), during exercise (8 min of the step test with an ascending frequency corresponding to 70% of individual maximal power output) and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Exercise recovery; Heart rate variability; Entropy; Spectral analysis; Parasympathetic system.
Ano: 2002 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002000800018
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Linear and nonlinear analysis of heart rate variability in healthy subjects and after acute myocardial infarction in patients BJMBR
Kunz,V.C.; Borges,E.N.; Coelho,R.C.; Gubolino,L.A.; Martins,L.E.B.; Silva,E..
The objectives of this study were to evaluate and compare the use of linear and nonlinear methods for analysis of heart rate variability (HRV) in healthy subjects and in patients after acute myocardial infarction (AMI). Heart rate (HR) was recorded for 15 min in the supine position in 10 patients with AMI taking β-blockers (aged 57 ± 9 years) and in 11 healthy subjects (aged 53 ± 4 years). HRV was analyzed in the time domain (RMSSD and RMSM), the frequency domain using low- and high-frequency bands in normalized units (nu; LFnu and HFnu) and the LF/HF ratio and approximate entropy (ApEn) were determined. There was a correlation (P < 0.05) of RMSSD, RMSM, LFnu, HFnu, and the LF/HF ratio index with the ApEn of the AMI group on the 2nd (r = 0.87, 0.65,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Myocardial infarction; Heart rate variability; Autonomic nervous system; Spectral analysis; Nonlinear dynamics.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012000500011
Registros recuperados: 39
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