SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Karp, Larry S.; Perloff, Jeffrey M..

A linear-quadratic, dynamic feedback oligopoly model that nests various market structures is used to estimate the degree of competitiveness and the adjustment paths of the two largest coffee exporters, Brazil and Colombia. Their estimated behavior is relatively competitive. This subgame perfect dynamic model is-compared to a standard static oligopoly model and the open-loop model (the dynamic generalization of the standard static model). Both classical and Bayesian tests of open-loop and feedback dynamic models are reported.

Tipo: Working or Discussion Paper

Palavras-chave: Export marketing; Mathematical models; International Relations/Trade; Crop Production/Industries.

Ano: 1990

URL: http://purl.umn.edu/47250

A importância do ajuste fino de distribuições de probabilidade em modelos baseados no indivíduo.

GALVÃO, M. M.; BARBOSA, F. F. L.; TERNES, S..

RESUMO - O Huanglongbing (HLB) é atualmente a principal doença para a citricultura mundial e no Brasil ela é transmitida principalmente pelo inseto vetor Diaphorina citri. A Embrapa vem realizando estudos para compreender o patossistema HLB - D. citri - citros, fazendo uso de modelos matemáticos computacionais seguindo a abordagem da modelagem baseada no indivíduo (MBI). Num MBI é possível representar as características de cada indivíduo da população e seus processos (nascimento, reprodução, morte, estados epidemiológicos), os quais evoluem estocasticamente e discretamente no tempo. O ajuste de distribuições de probabilidade e a garantia da aleatoriedade nos processos do modelo são muito importantes em um MBI, uma vez que o comportamento final da população...

A mathematical model to estimate the volume of grey water of pesticide mixtures.

Palavras-chave: Modelagem baseada no indivíduo; Distribuições de probabilidade; Modelagem matemática; Huanglongbing; Probability distributions; Mathematical modeling; Citriculture; Citricultura; Mathematical models.

Ano: 2018

URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1096174

A mathematical model to estimate the volume of grey water of pesticide mixtures.

PARAIBA, L. C.; PAZIANOTTO, R. A. A.; LUIZ, A. J. B.; MAIA, A. de H. N.; JONSSON, C. M..

The usual method to calculate grey water footprint does not take into account the volume of water required to dilute concentrations of pesticide mixtures in freshwater and it also depends on maximum concentration limit acceptable in water. We propose a model to estimate the grey water footprint of crops by calculating the volume of water necessary to dilute pesticide mixtures reaching freshwaters. The model requires short-term toxicity data from aquatic organisms based on EC50 values, soil pesticide half-life and soil sorption coefficient values, and does not require maximum concentration limit acceptable in water. The lixiviation rate and runoff rate of each pesticide was estimated by attenuation factor and by Soilfug model, respectively. The usefulness...

Tipo: Artigo em periódico indexado (ALICE)

Palavras-chave: Pesticide management; Water quality objective; Agrotóxico; Herbicida; Cana-de-açúcar; Qualidade da água; Modelo matemático; Herbicides; Environmental impact; Water quality; Water footprint; Sugarcane; Mathematical models.

Ano: 2014

URL: http://www.alice.cnptia.embrapa.br/handle/doc/1000149

PARAIBA, L. C.; PAZIANOTTO, R. A. A.; LUIZ, A. J. B.; MAIA, A. de H. N.; JONSSON, C. M..

Abstract: We propose a model to estimate the grey water footprint of crops by calculating the volume of water necessary to dilute pesticide mixtures reaching freshwaters. The model requires short-term toxicity data from aquatic organisms based on EC50 values, soil pesticide half-life and soil sorption coefficient values, and does not require maximum concentration limit acceptable in water. The lixiviation rate and runoff rate of each pesticide was estimated by attenuation factor and by Soilfug model, respectively. The usefulness of the proposed model was illustrated by estimating the volume of grey water required to dilute the 17 most widely used herbicides in sugarcane crops of Brazil. The grey water footprint corresponding to the recommended agronomic...

A modern view of Joseph's policy: food stocks as financial assets

Palavras-chave: Water footprint; Herbicide; Sugarcane; Toxicity; Agrotóxico; Cana-de-açúcar; Herbicida; Modelo matemático; Qualidade da água; Environmental impact; Herbicides; Mathematical models; Sugarcane; Water footprint; Water quality.

Ano: 2014

URL: http://www.alice.cnptia.embrapa.br/handle/doc/1007175

Adelman, Irma; Berck, Peter.

Tipo: Working or Discussion Paper

Palavras-chave: Food consumption; Mathematical models; Price stabilization; Prices; Risk; Supply and demand.

Ano: 1989

URL: http://purl.umn.edu/43666

A re-evaluation of marine nematode productivity

OMA

Vranken, G.; Herman, P.M.J.; Vincx, M.; Heip, C.H.R..

Nematodes are the most abundant multicellular animals in marine sediments but their role in the benthos has not been properly quantified yet. In nearly all energy-flow budgets of marine systems their annual production P is given as about nine times their biomass B and their part in the total energy-flow is consequently estimated as anywhere between 3 and 30% of the total (carbon) input in the benthic system. Our laboratory experiments demonstrate that nematode productivity is much higher than P/B ~ 9 per year and may reach values of over 60 for bacterial grazers. To obtain more reliable estimates for field populations we propose a regression equation relating egg-to-egg development time T<sub>min</sub> to temperature (t) and adult female weight...

Tipo: Info:eu-repo/semantics/article

Palavras-chave: Biological production; Mathematical models; Meiobenthos; Nematoda [Nematodes].

Ano: 1986

URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3576

A standard computable general equilibrium (CGE) model in GAMS

Lofgren, Hans; Harris, Rebecca Lee; Robinson, Sherman.

Over the past decade, the increasing power and reliability of microcomputers and the development of sophisticated software designed specifically for use with them has led to significant changes in the way quantitative food policy analysis is conducted. These changes cover most aspects of the analysis, ranging from the collections and analysis of socioeconomic data to the conduct of model-based policy simulations. The venue of the computations has shifted from off-site mainframes dependent on highly trained operators and significant capital investment in supporting equipment, to desktop and laptop computers dependent only on the occasional availability of electricity. This means that it is now feasible to quickly transfer new techniques between IFPRI and...

Tipo: Book

Palavras-chave: Agriculture; Economic aspects; Mathematical models; Food supply; Mathematical models; Equilibrium (Economics); Mathematical models; Research Methods/ Statistical Methods.

Ano: 2002

URL: http://purl.umn.edu/42483

A system for management and analysis of rice genomics data for candidate gene discovery

International Rice Research Institute

Mansueto, Locedie A..

xx, 165 l. : ill. Thesis (M.S.) -- University of the Philippines Diliman

Tipo: Thesis

Palavras-chave: Rice; Plant genetics; Information systems; Data analysis; Genomics; Mathematical models; Information management.

Ano: 2005

URL: http://hdl.handle.net/123456789/363

Ability of non-linear mixed models to predict growth in laying hens

R. Bras. Zootec.

Galeano-Vasco,Luis Fernando; Cerón-Muñoz,Mario Fernando; Narváez-Solarte,William.

In this study, the Von Bertalanffy, Richards, Gompertz, Brody, and Logistics non-linear mixed regression models were compared for their ability to estimate the growth curve in commercial laying hens. Data were obtained from 100 Lohmann LSL layers. The animals were identified and then weighed weekly from day 20 after hatch until they were 553 days of age. All the nonlinear models used were transformed into mixed models by the inclusion of random parameters. Accuracy of the models was determined by the Akaike and Bayesian information criteria (AIC and BIC, respectively), and the correlation values. According to AIC, BIC, and correlation values, the best fit for modeling the growth curve of the birds was obtained with Gompertz, followed by Richards, and then...

Tipo: Info:eu-repo/semantics/article

Palavras-chave: Chickens; Mathematical models; Poultry; Regression analysis; Weight gain.

Ano: 2014

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982014001100573

ACT Now or Later: The Economics of Malaria Resistance

Agro-climatic suitability and water requirement for Tanzania guineagrass cultivation in the State of Ceará.

Laxminarayan, Ramanan.

In the past, malaria control efforts in sub-Saharan Africa have relied on a combination of vector control and effective treatment using chloroquine. With increasing resistance to chloroquine, attention has now turned to alternative treatment strategies to replace this failing drug. Although there are strong theoretical arguments in favor of switching to more expensive artemisinin-based combination treatments (ACTs), the validity of these arguments in the face of financial constraints has not been previously analyzed. In this paper, we use a Bioeconomic model of malaria transmission and evolution of drug resistance to examine questions of optimal treatment strategy and coverage when drug resistance places an additional constraint on choices available to the...

Tipo: Working or Discussion Paper

Palavras-chave: Malaria; Mathematical models; Drug resistance; Bioeconomics; Health Economics and Policy; I10; I19; C61.

Ano: 2003

URL: http://purl.umn.edu/10699

LEMOS, N. L. S.; CAVALCANTE, A. C. R.; SILVA, T. G. F. da; PEZZOPANE, J. R. M.; SANTOS, P. M.; CÂNDIDO, M. J. D..

Abstracts: This study aimed to define areas suitable, and the irrigation water requirement for, cultivation of Tanzania guineagrass in the state of Ceará, Brazil. Tanzania guineagrass yield was estimated by a mathematical model, which considers the crop actual evapotranspiration, resulting from the crop climatological water balance. The water requirement throughout the year was estimated for soils with a water holding capacity of 20 (shallow soils), 40 (sandy soils), 60 (soils with medium texture) and 100 mm (clay soils). The relative frequency of occurrence of monthly productions greater than 2,750 kg DM ha-1 month-1 was obtained for different areas in Ceará, representative of most of the state's economic mesoregions. Tanzania guineagrass annual yields in...

Tipo: Artigo em periódico indexado (ALICE)

Palavras-chave: Capacidade de armazenamento de água; Taxa de acúmulo; Capim Tanzânia; Brasil; Ceará; Panicum maximum; Modelo matemático; Gramínea forrageira; Matéria seca; Mathematical models; Simulation models; Water requirements; Water storage; Pastures; Brazil.

Ano: 2017

URL: http://www.alice.cnptia.embrapa.br/handle/doc/1070933

Ajuste de modelo para quantificar o efeito de plantas daninhas e época de semeadura no rendimento de soja.

Ajustement de modèles mathématiques de la croissance d'algues phytoplanctoniques en culture

RIZZARDI, M.A.; FLECK, N.G.; RIBOLDI, J.; AGOSTINETTO, D..

O objetivo deste trabalho foi ajustar e validar um modelo matemático baseado em densidades de picão-preto (Bidens spp.) e de guanxuma (Sida rhombifolia L.), integrando a época de semeadura da soja após a dessecação da cobertura vegetal, para quantificar perdas de rendimento de grãos. Foram conduzidos quatro experimentos, em Passo Fundo e Eldorado do Sul. Os tratamentos constaram de densidades de picão-preto ou de guanxuma e de épocas de semeadura da soja em relação à data de dessecação da cobertura vegetal. Nos experimentos com picão-preto, a semeadura da soja foi realizada 3, 7 e 11 dias após dessecação (DAD) da cobertura vegetal, nos dois locais. Com infestação de guanxuma, a semeadura da soja foi realizada 3, 7 e 11 DAD em Passo Fundo, e 20, 24 e 28 DAD...

Tipo: Artigo em periódico indexado (ALICE)

Palavras-chave: Picão-preto; Guaxuma; Densidade de plantas daninhas; Perda de rendimento; Modelo matemático; Dessecação de cobertura vegetal; Beggarticks; Arrowleaf sida; Weed density; Crop yield losses; Mathematical models; Plant cover desiccation.

Ano: 2003

URL: http://www.alice.cnptia.embrapa.br/handle/doc/85693

ArchiMer

Le Berre, Jerome.

Introduction: This document is the End of Second Year internship report for Rennes University 1's Senior Math and Computer Science Modelisation Professional diploma. This two month internship was completed at the Brest IFREMER center at the Coastal Ecology department. IFREMER participates, in the course of its institutional missions, in observation and coastal sea surveillance, in order to improve on the knowledge, protection methods and restoration of the marine environment. Marine phytoplankton proliferation is an important study subject because of its potential cause for nuisance, for men, consumers of sea products as well as for the ecosystem. During Spring and Summer, shellfish become invariably unsuitable for consumption due to toxins produced by...

Tipo: Text

Palavras-chave: Aquaculture; Growth; Phytoplanctonic algae; Mathematical models.

Ano: 2000

URL: http://archimer.ifremer.fr/doc/2000/rapport-1770.pdf

Alarmas en un servicio que proporciona información oportuna e interpretable a sus clientes

Colegio de Postgraduados

Velázquez Castro, Gilberto David.

Para complementar los servicios de información a empresas o personas físicas, en cuanto a comunicar, no sólo cambios en sus variables de interés, sino el impacto que éstos tienen sobre las actividades de la empresa, se propone un servicio que calcula tales impactos con el uso de modelos matemáticos. Se puede generar una alarma al cliente, cuando los cambios satisfagan criterios que éste define para tal efecto. De acuerdo a la urgencia indicada, se comunicará al cliente por correo electrónico, mensaje de texto o una llamada de un empleado del servicio, alguna situación que pudiera requerir una decisión oportuna.______A service to customers was conceived in order to offer information about the impact of changes in their data, rather than just report...

Tipo: Tesis

Palavras-chave: Comunicación oportuna; Interpretable; Modelos matemáticos; Alarmas; Datos del entorno empresarial; Maestría; Computo Aplicado; Timely communicaction; Interpretable; Mathematical models; Alarms; Business environment data.

Ano: 2009

URL: http://hdl.handle.net/10521/1505

An Ag-dependent approach based on adaptive mechanisms for investigating the regulation of the memory B cell reservoir.

Análise biomatemática de enfezamentos na cultura do milho.

CASTRO, A. de..

In fact, it is well-known that the soluble antibody population is one of the essential mechanisms of immunological response regulation [23-25]. However, despite the pioneering work of Lagreca et al. (2001) in developing a coupled map for studying the behavior of the mammalian immune system, their model did not consider these populations [1-6], which makes the model incomplete with respect to the regulation of the immune response by adaptive mechanisms. This omission opens up the possibility of extending their work by taking the soluble antibody populations into account. We have performed that work and present our immunological modeling and simulation findings in this paper.

Tipo: Capítulo em livro científico (ALICE)

Palavras-chave: Modelo dinâmico; Modelo de simulação; Modelo matemático; Simulação dinâmica; Células B; Dynamic models; Simulation models; Mathematical models.

Ano: 2012

URL: http://www.alice.cnptia.embrapa.br/handle/doc/924382

SILVA, M. V. da; TERNES, S.; VILAMIU, R. G. d'A.; CASTRO, A.; BRAGA, G. A.; OLIVEIRA, E. de.

Com o interesse de analisar a evolucao das doencas conhecidas como enfezamentos pálido e vermelho na cultura do milho, que podem causar grande prejuízo econômico para a agricultura nacional, formulou-se um modelo matemático determinístico para avaliação da dinâmica temporal da incidência das doenças, considerando o sistema planta (milho) - inseto vetor (cigarrinha Dalbulus maidis). Os pontos de equilíbrio do sistema de equações diferenciais ordinárias que descreve o modelo e suas condições de estabilidade foram determinados. A partir do modelo matemático foram realizadas simulações numéricas utilizando-se valores encontrados na literatura para os parâmetros do modelo.

Análise biomatemática de enfezamentos na cultura do milho.

Palavras-chave: Cigarrinha; Enfezamento; Milho; Modelo matemático; Simulação; Cicadellidae; Corn; Dalbulus maidis; Mathematical models.

Ano: 2011

URL: http://www.alice.cnptia.embrapa.br/handle/doc/1040382

SILVA , M. V. da; TERNES, S.; VILAMIU, R. G. d'A.; CASTRO, A.; BRAGA, G. A.; OLIVEIRA, E. de..

RESUMO: Com o interesse de analisar a evolucao das doencas conhecidas como enfezamentos pálido e vermelho na cultura do milho, que podem causar grande prejuízo econômico para a agricultura nacional, formulou-se um modelo matemático determinístico para avaliação da dinâmica temporal da incidência das doenças, considerando o sistema planta (milho) - inseto vetor (cigarrinha Dalbulus maidis). Os pontos de equilíbrio do sistema de equações diferenciais ordinárias que descreve o modelo e suas condições de estabilidade foram determinados. A partir do modelo matemático foram realizadas simulações numéricas utilizando-se valores encontrados na literatura para os parâmetros do modelo.