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Registros recuperados: 74
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A time series analysis of bulk tank somatic cell counts of dairy herds located in Brazil and the United States. Repositório Alice
RODRIGUES, L. G..
Bulk tank somatic cell counts (BTSCC) is widely used to monitore the mammary gland health at the herd and regional level. The BTSCC time series from specific regions or countries can be used to compare the mammary gland health and estimate the trend of subclinical mastitis at the regional level. Three time series of BTSCC from dairy herds located in the USA and the Southeastern Brazil were evaluated from 1995 to 2014. Descriptive statistics and a linear regression model were used to evaluate the data of the BTSCC time series. The mean of annual geometric mean of BTSCC (AGM) and the percentage of dairy herds with a BTSCC greater than 400,000 cells mL-1 (%>400) were significantly different (P<0.05) according to the countries and the times series....
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Bulk tank somatic cell counts; Time series; Bovine mastitis; Brazil; United States.
Ano: 2017 URL: http://www.alice.cnptia.embrapa.br/handle/doc/1072269
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A time series analysis of bulk tank somatic cell counts of dairy herds located in Brazil and the United States Ciência Rural
Rodrigues,Liz Gonçalves; Aquino,Maria Helena Cosendey de; Silva,Márcio Roberto; Mendonça,Letícia Caldas; Mendonça,Juliana França Monteiro de; Souza,Guilherme Nunes de.
ABSTRACT: Bulk tank somatic cell counts (BTSCC) is widely used to monitore the mammary gland health at the herd and regional level. The BTSCC time series from specific regions or countries can be used to compare the mammary gland health and estimate the trend of subclinical mastitis at the regional level. Three time series of BTSCC from dairy herds located in the USA and the Southeastern Brazil were evaluated from 1995 to 2014. Descriptive statistics and a linear regression model were used to evaluate the data of the BTSCC time series. The mean of annual geometric mean of BTSCC (AGM) and the percentage of dairy herds with a BTSCC greater than 400,000 cells mL-1 (%>400) were significantly different (P<0.05) according to the countries and the times...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Bulk tank somatic cell counts; Time series; Bovine mastitis; Brazil; United States.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782017000400451
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Abrupt shifts in the Gironde fish community: an indicator of ecological changes in an estuarine ecosystem ArchiMer
Chevillot, Xavier; Pierre, Maud; Rigaud, Arthur; Drouineau, Hilaire; Chaalali, Aurelie; Sautour, Benoit; Lobry, Jeremy.
For decades, global climate change has directly and indirectly affected the structure and function of ecosystems. Abrupt changes in biodiversity have been observed in response to linear or sudden modifications to the environment. These abrupt shifts can cause long-term reorganizations within ecosystems, with communities exhibiting new functional responses to environmental factors. Over the last 3 decades, the Gironde estuary in southwest France has experienced 2 abrupt shifts in both the physical and chemical environments and the pelagic community. Rather than describing these shifts and their origins, we focused on the 3 inter-shift periods, describing the structure of the fish community and its relationship with the environment during these periods. We...
Tipo: Text Palavras-chave: Ecosystem state; Fish diversity; Estuary; Generalised linear mixed models; GLMM; Time series; Shift; Inter-shift periods.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00334/44567/44282.pdf
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Advanced spectral analysis and cross correlation based on the empirical mode decomposition: application to the environmental time series ArchiMer
Ben Ismail, Dhouha Kbaier; Lazure, Pascal; Puillat, Ingrid.
Abstract—In marine sciences, time series are often nonlinear and nonstationary. Adequate and specific methods are needed to analyze such series. In this paper, an application of the Empirical Mode Decomposition method (EMD) associated to the Hilbert Spectral Analysis (HSA) is presented. Furthermore, EMD based Time Dependent Intrinsic Correlation (TDIC) analysis is applied to consider the correlation between two nonstationary time series. Four temperature time series obtained from automatic measurements in nearshore waters of the Réunion island are considered, recorded every ten minutes from July 2011 to January 2012. The application of the EMD on these series and the estimation of their power spectra using the HSA are illustrated. The authors identify...
Tipo: Text Palavras-chave: Augmented Dickey-Fuller tests; Cross correlation; Empirical mode decomposition (EMD); Hilbert spectral analysis (HSA); Hilbert-Huang transform (HHT); Stationarity; Time-dependent intrinsic correlation (TDIC); Time series; Wavelets.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00270/38077/36205.pdf
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AGGREGATION ISSUES IN THE ESTIMATION OF MALMQUIST PRODUCTIVITY MEASURES AgEcon
Shaik, Saleem.
The paper contributes by demonstrating the sensitivity of nonparametric programming productivity measures to the choice of model –time series versus panel models of Malmquist productivity, and to various levels of commodity aggregation compared to the traditional Tornqvist-Theil index approach employing U.S. state-level data from 1960-96. To illustrate the sensitive of nonparametric programming productivity measures, we compare the implicit shadow shares recovered from the dual values of the Malmquist productivity and total factor productivity methods to the observed shares of the Tornqvist-Theil index for U.S level data from 1948-1994.
Tipo: Conference Paper or Presentation Palavras-chave: Tornqvist-Theil Index; Time series; And Panel models; Malmquist productivity and Malmquist total factor productivity programming; Share-weights.; Productivity Analysis; O3; C6; Q1.
Ano: 2009 URL: http://purl.umn.edu/46553
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Análise harmônica de séries temporais de imagens NDVI/MODIS para discriminação de coberturas vegetais. Repositório Alice
VICTORIA, D. D. C.; OLIVEIRA, A. F. D.; GREGO, C. R..
The high temporal resolution information obtained with the Moderate Resolution Imaging Spectroradiometer (MODIS) is of great value when it comes to monitoring changes in Earth surface. Since several land cover types presents a distinguished temporal pattern in it?s spectral response, MODIS high temporal resolution can be used to identify such covers. This is specially true when observing the Normalized Difference Vegetation Index (NDVI) of agricultural land covers. Fourier transformations decomposes any signal represented in time to a frequency domain. Applying this transformation in a NDVI time-series results in parameters that describe how this signal behaves along several time frequencies (annual, semestral, etc). A strong annual signal indicates a land...
Tipo: Artigo em anais de congresso (ALICE) Palavras-chave: MODIS; NDVI; Time series; Fourier; Series temporais.
Ano: 2009 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/32122
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Análisis de tendencia de series de tiempo oceanográficas y meteorológicas para determinar evidencias de cambio climático en la costa del Ecuador OceanDocs
Nieto, J.J.; Martínez, R.; Regalado, J.; Hernández, F..
El propósito de la investigación es evidenciar la influencia física del cambio climático global en la costa del Ecuador, procurando inferir escenarios más precisos a escala local, en cuanto a temperatura del mar, temperatura del aire y nivel medio del mar.
Tipo: Journal Contribution Palavras-chave: Time series; Oceanographic data; Meteorological data; Surface temperature; Mean sea level; Air temperature; Climatic changes; Climatology; Water temperature data; Coastal zone; Climatology; Meteorological data; Air temperature; Http://aims.fao.org/aos/agrovoc/c_1671; Http://aims.fao.org/aos/agrovoc/c_34149; Http://aims.fao.org/aos/agrovoc/c_230.
Ano: 2002 URL: http://hdl.handle.net/1834/2246
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Análisis de tendencias en valores extremos de variables meteorológicas importantes para la agricultura. Colegio de Postgraduados
Blanco Ramírez, Ma. Esperanza.
Se propone una metodología basada en la teoría de valores extremos para investigar cambios espacio temporales en la tendencia a largo plazo de variables meteorológicas (precipitación y temperatura). Se presenta un ejemplo de aplicación para el estado de Durango, México, analizando los máximos anuales de las variables temperatura máxima, temperatura mínima y precipitación ocurridos durante el período de 1961 a 2000. Esta metodología puede ser de utilidad en la investigación del cambio climático a nivel regional. Los resultados se presentan en mapas de tendencias de eventos extremos. Para el caso del estado de Durango se observan cambios en el comportamiento de eventos extremos, manifestándose una clara tendencia a la ocurrencia de años más secos y más...
Palavras-chave: Series de tiempo; Modelo Lineal Vectorial Generalizado; Interpolación espacial; Time series; Extreme value theory; Vector generalized linear model; Spatial interpolation; Estadísica; Maestría.
Ano: 2012 URL: http://hdl.handle.net/10521/1728
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Analyse des déterminants environnementaux de la variabilité du recrutement - approche macroécologique appliquée aux populations exploitées du Nord-Est Atlantique ArchiMer
Brunel, Thomas.
Recruitment - the number of young fishes that integrate each year the exploitable stock¿ has a central importance for stock dynamics. The high temporal variability in recruitment is a result of the environmental influence on survival during early life stages. Understanding the determinism of the influence of environment on recruitment remains one of the most important question in fisheries ecology. The present work aimed at answering some general questions about the influence of environment on fish recruitment using a macroecological approach. The study focused on the exploited fish populations of the Northeastern Atlantic. The first chapter of the thesis makes a review of the different methods used to estimate recruitment, compares recruitment estimates...
Tipo: Text Palavras-chave: Time series; Recruitment variability; Regime shift; Recruitment synchrony; North East Atlantic; NAO; Long term trends; Environmental influence; Effect of temperature; Effect of fishing; Climate change; Biogeography; Variabilité du recrutement; Synchronisme; Séries chronologiques; Tendances à long terme; NAO; Influence de l'environnement; Effet de la température; Effet de la pêche; Changement de régime; Changement climatique; Biogéographie; Atlantique Nord Est.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/these-1113.pdf
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Analyse harmonique des séries chronologiques des niveaux d’eau et des courants au niveau de RasTaguermess et à el kantara dans le golfe de Gabès OceanDocs
Atoui., A.; Brahim, M.; Sammari, Ch..
Dans le cadre d’un programme national concernant l’étude de la circulation des eaux dans le littoral tunisien nous avons installé des courantomètres et des houlographes marégraphes dans le golfe de Gabès et notamment à l’Est de Djerba, en face de Ras-Taguermess et au niveau d’El Kantara. L’analyse harmonique des séries temporelles de niveau d’eau au niveau de Ras Taguermess et El-Kantara montre la dominance des composantes de la marée semi-diurne avec prédominance de la composante semi-diurne (M2) de période 12 h 25 mn. L’analyse en composantes principales où en fonction orthogonale empirique (EOF) des courants de la marée montre qu’au niveau d’El- Kantara la vitesse des courants est de 45 cm.s-1 et que sa direction est de 29° par rapport à l’Est ;...
Tipo: Journal Contribution Palavras-chave: Coastal waters; Current velocity; Harmonic analysis; Tidal currents; Time series; Water circulation; Water currents; Water levels.
Ano: 2009 URL: http://hdl.handle.net/1834/4618
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Analysis of grassland degradation in Zona da Mata, MG, Brazil, based on NDVI time series data with the integration of phenological metrics. Repositório Alice
HOTT, M. C.; CARVALHO, L. M. T.; ANTURNES, M. A. H.; RESENDE, J. C. de; ROCHA, W. S. D. da.
Abstract: There is currently a lot of interest in determining the state of Brazilian grasslands. Governmental actions and programs have recently been implemented for grassland recovery in Brazilian states, with the aim of improving production systems and socioeconomic indicators. The aim of this study is to evaluate the vegetative growth, temporal vigor, and long-term scenarios for the grasslands in Zona da Mata, Minas Gerais State, Brazil, by integrating phenological metrics. We used metrics derived from the normalized difference vegetation index (NDVI) time series from moderate resolution imaging spectroradiometer (MODIS) data, which were analyzed in a geographic information system (GIS), using multicriteria analysis, the analytical hierarchy process,...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Time series; NDVI; Phenological metrics; Remote sensing; Degradation; Grasslands.
Ano: 2019 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1118582
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Analysis of rhythmic variance - ANORVA. A new simple method for detecting rhythms in biological time series Biol. Res.
Celec,Peter.
Cyclic variations of variables are ubiquitous in biomedical science. A number of methods for detecting rhythms have been developed, but they are often difficult to interpret. A simple procedure for detecting cyclic variations in biological time series and quantification of their probability is presented here. Analysis of rhythmic variance (ANORVA) is based on the premise that the variance in groups of data from rhythmic variables is low when a time distance of one period exists between the data entries. A detailed stepwise calculation is presented including data entry and preparation, variance calculating, and difference testing. An example for the application of the procedure is provided, and a real dataset of the number of papers published per day in...
Tipo: Journal article Palavras-chave: Chronobiology; Time series; Method; ANORVA; Analysis of rhythmic variance; Circaseptan; Cycle; Rhyth.
Ano: 2004 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000500007
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Analysis of time series of planktonic communities in the Adriatic Sea: Distinguishing between natural and man-induced changes ArchiMer
Solic, M; Krstulovic, N; Marasovic, I; Baranovic, A; Pucherpetkovic, T; Vucetic, T.
Time series (> 20 years) of bacterioplankton, phytoplankton and zooplankton abundances and of phytoplankton production in the Adriatic Sea were analysed. Multivariate methods were used to extract the main patterns of year-to-year changes in abundances (Principal Component Analysis), and to discriminate between years and sites (Multidimensional Scaling). Increasing long-term trends were established for planktonic abundances and phytoplankton production in both coastal and open sea areas, presumably as a result of eutrophication processes. In the open sea, natural factors (water exchange between the Mediterranean and Adriatic Seas, and temperature) were dominant in controlling year-to-year fluctuations of plankton. On the other hand, long-term...
Tipo: Text Palavras-chave: Plankton; Time series; Natural factors; Man-induced factors.
Ano: 1997 URL: http://archimer.ifremer.fr/doc/00093/20386/18053.pdf
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Application of Hilbert-Huang decomposition to temperature and currents data in the Réunion island ArchiMer
Kbaier-ben Ismail, Dhouha; Lazure, Pascal; Puillat Felix, Ingrid.
In marine sciences, time series are often nonlinear and nonstationary. Their analysis faces new challenges and thus requires the implementation of adequate and specific methods. We use the Hilbert-Huang Transform (HHT) for the spectral analysis of high frequency sampled time series in near shore waters of the Réunion island, located in the Indian Ocean 700 km east of Madagascar. We focus particularly on automatic measurements of sea level fluctuations, temperature records and current data sets at four different stations in the island. We look at the contribution of different Intrinsic Mode Functions (IMFs) obtained by the Empirical Mode Decomposition (EMD) and also compare the Hilbert spectra with the wavelet spectra. The inertial wave and several...
Tipo: Text Palavras-chave: Cross correlation; Empirical mode decomposition (EMD); Hilbert spectral analysis (HSA); Hilbert-Huang transform (HHT); Stationarity; Time-dependent intrinsic correlation (TDIC); Time series; Wavelets.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00383/49392/49822.pdf
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ARTIFICIAL NEURAL NETWORKS FOR PREDICTING ANIMAL THERMAL COMFORT REA
Borges,Pedro H. M.; Mendoza,Zaíra M. S. H. de; Morais,Pedro H. M.; Santos,Ronei L. dos.
ABSTRACT The objective of this study was to develop artificial neural networks (ANNs) for predicting animal thermal comfort based on temperature and relative humidity of the air for each day of the year. The data on temperature and relative humidity for a 25-year historical series collected at the Padre Ricardo Remetter Conventional Meteorological Station, located in the city of Santo Antônio de Leverger - Mato Grosso (Brazil), were retrieved from the website of the National Institute of Meteorology. According to the day of the year, the temperature and humidity index was determined as a function of the climatic variables. Therefore, the day of the year was the input variable of the neural networks, and the temperature and humidity index (THI) was the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Time series; Artificial intelligence; Comfort index.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162018000600844
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Assessing Changes in Fisheries Using Fishers&#8217; Knowledge to Generate Long Time Series of Catch Rates: a Case Study from the Red Sea Ecology and Society
Tesfamichael, Dawit; Fisheries Centre, University of British Columbia; Department of Marine Science, University of Asmara; d.tesfamichael@fisheries.ubc.ca; Pitcher, Tony J.; Fisheries Centre, University of British Columbia; pitcher.t@gmail.com; Pauly, Daniel; Fisheries Centre, University of British Columbia; d.pauly@fisheries.ubc.ca.
The data requirements for most quantitative fishery assessment models are extensive, and most of the fisheries in the world lack time series of the required biological and socioeconomic data. Many innovative approaches have been developed to improve data collection for fisheries. We explored the use of data from fishers&#8217; interviews to estimate time series of approximate &#8220;best&#8221; catch rates. A total of 472 standardized interviews were conducted with 423 fishers along the southern Red Sea coast recording the best catch recalled and the change in average catch rates throughout the fishing career of interviewees. The results showed a decline of best catch rates in all fisheries, ranging from 4% to 10% per year for more than 50...
Tipo: Peer-Reviewed Reports Palavras-chave: Assessment; Catch rates; Fishers&#8217; Knowledge; Interview; Red Sea; Small-scale fishery; Time series.
Ano: 2014
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Behavioural study of two Hydrothermal crustacean decapods: Mirocaris fortunata and Segonzacia mesatlantica, from the lucky strike vent field (mid-Atlantic ridge) ArchiMer
Matabos, Marjolaine; Cuvelier, D.; Brouard, J.; Shillito, B.; Ravaux, J.; Zbinden, M.; Barthelemy, D.; Sarradin, Pierre-marie; Sarrazin, Jozee.
Identifying the factors driving community dynamics in hydrothermal vent communities, and in particular biological interactions, is challenged by our ability to make direct observations and the difficulty to conduct experiments in those remote ecosystems. As a result, we have very limited knowledge on species’ behaviour and interactions in these communities and how they in turn influence community dynamics. Interactions such as competition or predation significantly affect community structure in vent communities, and video time-series have successfully been used to gain insights in biological interactions and species behaviour, including responses to short-term changes in temperature or feeding strategies. In this study, we combined in situ and ex situ...
Tipo: Text Palavras-chave: Abyss Box; Biological interactions; Deep-sea observatory; Eiffel Tower edifice; Feeding behaviour; Experimental research; Video imagery; Time series; Lucky Strike; Mid-Atlantic Ridge; 37 degrees 17 ' N; 32 degrees 16.3 ' W.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00266/37714/35732.pdf
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CLIMATE CHANGE AND RURAL WORKERS THERMAL COMFORT: HISTORICAL AND FUTURE IMPACTS REA
Amaro,André L. N.; Yanagi Junior,Tadayuki; Yanagi,Sílvia de N. M.; Ferraz,Gabriel A. E S.; Campos,Alessandro T..
Abstract The aim of the present research was to propose a bioclimatic mapping to classify the thermal comfort and discomfort of rural workers within the state of Minas Gerais, considering historical and future scenarios. Monthly historical series (1976-2014) of minimum, mean and maximum temperature-humidity index (THI), determined through the values of air temperature (minimum, mean and maximum) and relative humidity from 48 weather stations located in the state of Minas Gerais were used to analyze the trends through Mann-Kendall and linear regression assays. The bioclimatic mapping of human comfort, obtained via geostatistical analysis, was developed as a function of the minimum, medium and maximum THI for the historical period (1976-2014) and future...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Human; Biometeorology; Human thermal comfort; THI; Time series.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162018000200173
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Climatic trends in continental shelf waters off Ghana and in the Gulf of Guinea, 1963-1992 ArchiMer
Koranteng, Ka; Mcglade, Jm.
Using time series analyses, some physical parameters of the continental shelf waters of the Gulf of Guinea were examined. Analysis of coastal sea surface temperatures from Ghana and Ivory Coast, and offshore sea surface temperatures from the Gulf of Guinea clearly shows spatial and inter-annual patterns of cooling in coastal waters of West Africa. The behaviour of the decomposed trend of coastal and offshore sea surface temperatures, sub-surface: temperature measured at 100 m depth off Ghana and salinity showed that the observational period (1963-1992) could be divided into three climatic periods: the period before 1972, from 1972 to 1982, and the period after 1982. In the first period, sea surface temperature at both coastal and offshore areas and bottom...
Tipo: Text Palavras-chave: Environnement marin; Afrique de l'Ouest; Séries temporelles; Marine environment; West Africa; Time series.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00322/43363/42852.pdf
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Coastal phytoplankton community dynamics and coexistence driven by intragroup density-dependence, light and hydrodynamics ArchiMer
Barraquand, F.; Picoche, C.; Maurer, Daniele; Carassou, L.; Auby, Isabelle.
Phytoplanktonic communities maintain a high diversity in a seemingly homogeneous environment, competing for the same set of resources. Many theories have been proposed to explain this coexistence despite likely competition, such as contrasted responses to temporal environmental variation. However, theory has developed at a faster pace than empirical evaluation using field data, which requires inferring drivers of community dynamics from observational time series. Here, we combine autoregressive models with a data set spanning more than 20 years of phytoplankton counts every two weeks, together with nutrients and physical variables. By comparing models dominated by nutrients or physical variables (hydrodynamics and climate), we first explore which abiotic...
Tipo: Text Palavras-chave: Competition; Diatoms; Dinoflagellates; Hydrodynamics; Interactions; MAR; Mutualism; Network; Population dynamics; Seasonality; Time series.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00461/57257/59285.pdf
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