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Registros recuperados: 179
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A Comparison of Timber Models for Use in Public Policy Analysis AgEcon
Sohngen, Brent; Sedjo, Roger A..
In this paper, we compare and contrast two types of timber models that have been used for public policy analysis. These models have been variously used to predict price, inventory and market welfare impacts under different exogenous forces that impact timber markets. The framework and theory for each model type is presented and discussed. We then thoroughly test the two model types across six potential exogenous shocks to timber markets, ranging from instantaneous demand shocks to gradual supply adjustments. Our comparison indicates that these models predict potentially important differences in timber market behavior. These differences are important to consider for those who do public policy analysis.
Tipo: Working or Discussion Paper Palavras-chave: Timber markets; Models; Dynamic adjustment; Optimization; Resource /Energy Economics and Policy; C62; Q21; Q23.
Ano: 1996 URL: http://purl.umn.edu/10467
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A dairy goat model to study the impacts on herd dynamics. Repositório Alice
GUIMARÃES, V. P.; TEDESCHI, L. O.; RODRIGUES, M. T..
The understanding of a dairy goat production system is crucial to establish a more competitive activity. Therefore, a simulation model was built to evaluate the dynamics of dairy goat herd under different scenarios of production. A System Dynamics approach was used to identify management policies that affect the behavior of the herd. All parameters considered in this model assumed average values reported in production systems in the Southeast region of Brazil. To simulate a herd in dynamic equilibrium, the culling and retention rates were used. Thereafter, simulations were performed based on changes in reproductive and mortality rates. All the simulations were planned to take the variation in herd development based on simple management strategies over 10...
Tipo: Nota Técnica/Nota Científica (ALICE) Palavras-chave: Região Sudeste; Brasil; Cabra leiteira; Modelo animal; Sistema de produção; Melhoramento genético animal; Goats; Models; Breeding; Production; Brazil.
Ano: 2009 URL: http://www.alice.cnptia.embrapa.br/handle/doc/939897
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A laboratory model system for analysing microbial interactions occurring in anoxic estuarine sediments. ArchiMer
Herbert, R; Keith, S.
Defined mixed populations of Clostridium butyricum, Desulfovibrio desulfuricans and Chromatium vinosum co-existed for long periods when grown in a single stage chemostat with glucose as sole carbon source. The nature and availability of the inorganic nitrogen source exerted a major effect on carbon flow in the experimental system. The data show that both the C. butyricum and D. desulfuricans isolates can utilise NO sub(3) as an e super(-)acceptor with an increase in cell yield. Under these growth conditions the free S super(2-) levels were lower resulting in more stable mixed populations. In addition the data show that the C. butyricum produces more oxidised fermentation end-products (acetate) when NO sub(3) super(-) was available and more reduced products...
Tipo: Text Palavras-chave: Chromatium vinosum; Desulfovibrio desulfuricans; Clostridium butyricum; Biogeochemistry; Models; Bacteria; Detritus; Mineralization; Anoxic sediments; Estuarine sedimentation; Analytical techniques; Carbon cycle; Interspecific relationships; Microbiology.
Ano: 1984 URL: http://archimer.ifremer.fr/doc/1984/acte-947.pdf
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A model for the study of skeletal anomalies in rat fetuses BABT
Effting,Cristiane; Paula,Daniel Jesus de; Nunes Junior,Guilhermino Pereira.
The aim of this study was to validate a model of skeletal anomalies in rat fetuses by the administration of ketoconazole (80 mg/kg) to pregnant rats during organogenesis. Bones of the head, trunk and anterior and posterior limbs were examined for detection of anomalies. Statistical differences regarding the number of fetuses and postimplantation resorptions, and fetal and placental weight were significant. The frequency of skeletal anomalies in the head, trunk, and anterior and posterior limbs in the ketoconazole-treated group were also significant when compared to the control group. It could be concluded that the model suggested was valid for study of skeletal anomalies and abnormal bones development in rat fetuse, in spite of the loss of fetuses due to...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Azol Antifungals; Ketoconazole; Models; Pregnancy; Skeletal Malformation; Steroids; Teratogenesis; Wistar Rats.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132004000100005
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A modeling approach to optimize nitrogen dose for drum-seeded wet rice International Rice Research Institute
Subramanian, E.; Martin, G. J.; Kailasam, C..
p.41-42
Palavras-chave: Nitrogen fertilizers; Application rates; Crop yield; Yield components; Models; India.
Ano: 2005 URL: http://hdl.handle.net/123456789/1118
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Adaptive Ecosystem Management in the Pacific Northwest: a Case Study from Coastal Oregon Ecology and Society
Gray, Andrew N; U.S. Forest Service Pacific Northwest Research Station; agray01@fs.fed.us.
Adaptive ecosystem management has been adopted as a goal for decision making by several of the land management and regulatory agencies of the U.S. government. One of the first attempts to implement ecosystem management was undertaken on the federally managed forests of the Pacific Northwest in 1994. In addition to a network of reserve areas intended to restore habitat for late-successional terrestrial and aquatic species, "adaptive management areas" (AMAs) were established. These AMAs were intended to be focal areas for implementing innovative methods of ecological conservation and restoration and meeting economic and social goals. This paper analyzes the primary ecological, social, and institutional issues of concern to one AMA in the Coast Range in...
Tipo: Peer-Reviewed Reports Palavras-chave: Adaptive management; Adaptive management area; Ecosystem management; Forest ecology; Landscape ecology; Models; Monitoring; Old-growth forest; Public involvement.
Ano: 2000
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Adoption and impacts of microirrigation technologies: Empirical results from selected localities of Maharashtra and Gujarat states of India AgEcon
Namara, Regassa E.; Upadhyay, Bhawana; Nagar, Rashmi K..
This report analyzes the economics of alternative microirrigation technologies ranging from low-cost drip and sprinkler systems to the capital-intensive systems, the determinants of adoption of microirrigation technology, the poverty outreach of the different microirrigation systems, and the sustainability implications of microirrigation adoption.
Tipo: Report Palavras-chave: Irrigation systems; Microirrigation; Models; Poverty; Rural women; Cropping systems; Food security; Economic aspects; Agribusiness; Agricultural and Food Policy; Community/Rural/Urban Development; Consumer/Household Economics; Crop Production/Industries; Food Security and Poverty.
Ano: 2005 URL: http://purl.umn.edu/44543
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Adsorption of glyphosate in Chilean soils and its relationship with unoccupied phosphate binding sites. Repositório Alice
KOGAN, M.; METZ, A.; ORTEGA, R..
The objective of this work was to investigate glyphosate adsorption by soils and its relationship with unoccupied binding sites for phosphate adsorption. Soil samples of three Chilean soils series - Valdivia (Andisol), Clarillo (Inceptisol) and Chicureo (Vertisol) - were incubated with different herbicide concentrations. Glyphosate remaining in solution was determined by adjusting a HPLC method with a UV detector. Experimental maximum adsorption capacity were 15,000, 14,300 and 4,700 mg g-1 for Valdivia, Clarillo, and Chicureo soils, respectively. Linear, Freundlich, and Langmuir models were used to describe glyphosate adsorption. Isotherms describing glyphosate adsorption differed among soils. Maximum adjusted adsorption capacity with the Langmuir model...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Herbicide; Dosage effects; Models; Herbicida; Efeito de dosagem; Modelos.
Ano: 2003 URL: http://www.alice.cnptia.embrapa.br/handle/doc/108986
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Adsorption of glyphosate in chilean soils and its relationship with unoccupied phosphate binding sites PAB
Kogan,Marcelo; Metz,Alejandra; Ortega,Rodrigo.
The objective of this work was to investigate glyphosate adsorption by soils and its relationship with unoccupied binding sites for phosphate adsorption. Soil samples of three Chilean soils series - Valdivia (Andisol), Clarillo (Inceptisol) and Chicureo (Vertisol) - were incubated with different herbicide concentrations. Glyphosate remaining in solution was determined by adjusting a HPLC method with a UV detector. Experimental maximum adsorption capacity were 15,000, 14,300 and 4,700 mg g¹ for Valdivia, Clarillo, and Chicureo soils, respectively. Linear, Freundlich, and Langmuir models were used to describe glyphosate adsorption. Isotherms describing glyphosate adsorption differed among soils. Maximum adjusted adsorption capacity with the Langmuir model...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Herbicide; Dosage effects; Models.
Ano: 2003 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2003000400010
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AGRICULTURAL EXTENSION SERVICE IN THE FUNCTION OF RURAL DEVELOPMENT AgEcon
Zivkovic, Dragic; Jelic, Sreten; Rajic, Zoran.
Agriculture and agricultural extension service are facing numerous problems in present times when good solutions are not easy to find. Providing of agricultural extension service is important foreign-political instrument of a state which has stimulates the development of agricultural production. Agricultural extension service must provide effective link between holdings-producers, agricultural research and other sources of information. Agricultural extension agents must be aware of psycho-social and social aspects of group action and individual counselling. Therefore, one of priorities in agricultural development of our country is rising of the level of extension operation and establishment of extension service based on modern principles. This is the...
Tipo: Conference Paper or Presentation Palavras-chave: Agricultural extension service; Types; Models; Functioning; Human resources; Agribusiness; Community/Rural/Urban Development; Teaching/Communication/Extension/Profession.
Ano: 2009 URL: http://purl.umn.edu/57507
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Agro-climatic aptitude for Tanzania guinea grass cultivation in Brazilian semiarid environment. Repositório Alice
CAVALCANTE, A. C. R.; LEMOS, N. L. S.; SILVA, T. G. F. da; SANTOS, P. M.; PEZZOPANE, J. R. M.; CÂNDIDO, M. J. D..
2015
Tipo: Artigo em anais de congresso (ALICE) Palavras-chave: Semiárido; Sazonalidade; Degree-days; ETA model; Mudança climática; Forragem; Gramínea forrageira; Chuva; Impacto ambiental; Panicum maximum; Rain; Semiarid climate; Brazil; Seasonality; Water balance; Climate change; Livestock; Models.
Ano: 2015 URL: http://www.alice.cnptia.embrapa.br/handle/doc/1033028
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Alexandrium minutum growth controlled by phosphorus An applied model ArchiMer
Chapelle, Annie; Labry, Claire; Sourisseau, Marc; Lebreton, Carole; Youenou, Agnes; Crassous, Marie-pierre.
Toxic algae are a worldwide problem threatening aquaculture public health and tourism Alexandrium a toxic dinoflagellate proliferates in Northwest France estuaries (i e the Penze estuary) causing Paralytic Shellfish Poisoning events Vegetative growth and in particular the role of nutrient uptake and growth rate are crucial parameters to understand toxic blooms With the goal of modelling in situ Alexandrium blooms related to environmental parameters we first try to calibrate a zero-dimensional box model of Alexandrium growth This work focuses on phosphorus nutrition Our objective is to calibrate Alexandrium minutum as well as Heterocapsa triquetra (a non-toxic dinoflagellate) growth under different rates of phosphorus supply other factors being optimal and...
Tipo: Text Palavras-chave: Toxic algal blooms; Alexandrium; Phosphorus uptake; Models; Competition; Northwest France.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00018/12901/9905.pdf
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Allometric models for estimating aboveground biomass and biomass allocation of capixingui trees (Croton floribundus Spreng.) in an agrisilvicultural system. Repositório Alice
NICODEMO, M. L. F.; MULLER, M. D.; CARPANEZZI, A. A.; PORFIRIO-DA-SILVA, V..
O objetivo deste estudo foi selecionar equações alométricas para predição da biomassa aérea total e nos compartimentos aéreos de capixingui com 4,5 anos estabelecidas em um sistema silviagrícola. Foram tomadas medidas dendrométricas e utilizou-se o método destrutivo para a estimação da biomassa, com a separação dos componentes em tronco, galhos e folhas. Foram ajustados e comparados quatro modelos alométricos, sendo dois de simples entrada e dois de dupla entrada. Como variáveis preditoras foram considerados o diâmetro à altura do peito (DAP), diâmetro de colo (D colo), diâmetro de copa (Dc) e altura total (H). A biomassa total estimada foi de 17,3 t.ha-1, equivalente a 86,6 kg por árvore. Todos os modelos apresentaram ajustes satisfatórios (R2aj>0,85)...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Capixingui; Sistema agroflorestal; Sistemas de integração da produção; Modelagem; Biomassa; Croton floribundus; Agroforestry; Integrated agricultural systems; Models; Aboveground biomass.
Ano: 2016 URL: http://www.alice.cnptia.embrapa.br/handle/doc/1045186
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Alternative methods and models for analyzing the impact of mechanization-- a case study of selected rice growing household in North China International Rice Research Institute
Sun, Haoxun.
102 l. : ill. Thesis (M.S.) -- University of the Philippines at Los Banos
Tipo: Thesis Palavras-chave: Rice; Agricultural machinery and equipment; Mechanization; Economic impact; Models; Households; China.
Ano: 1990 URL: http://hdl.handle.net/123456789/978
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An assessment of crop water productivity in the Indus and Ganges River Basins: current status and scope for improvement AgEcon
Cai, Xueliang; Sharma, Bharat R.; Matin, Mir Abdul; Sharma, Devesh; Gunasinghe, Sarath.
The Indus and Ganges River Basin, being the most populous in the world, is under extreme pressure to sustain food security. Production resources including water are being exploited to various levels from underdevelopment to heavy overexploitation. This report provides a bird’s eye view of the basin and focuses on the nexus between agricultural production and water consumption, making it possible to pinpoint the areas with high/low water productivity and identify the factors behind this, which helps to promote informed decision making in light of environmental sustainability.
Tipo: Report Palavras-chave: Water productivity; Crops; Yields; Rice; Wheat; River basins; Models; Remote sensing; Evapotranspiration; Mapping; Crop Production/Industries; Food Security and Poverty.
Ano: 2010 URL: http://purl.umn.edu/112970
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An assessment of volume-ratio functions for Eucalyptus globulus and E. nitens in Chile Ciencia e Investigación Agraria
Gilabert,Horacio; Paci,Carlos.
Volume-ratio and total volume models for Eucalyptus nitens and E. globulus grown in southern Chile were ftted independently. The validation process considered the bias and the total error in the volume estimates, as well as the age classes close to thinning and harvesting operations. Volume estimates from the system of functions (volume and ratio) were compared to the volume estimates from a taper function (Bruce model) to estimate the volume at different top stem diameters. The results indicated that general (as opposed to local) logarithmic functions performed better in their estimation of the total volume for both species, while a unique polynomial model was the best model for the ratio estimates for both Eucalyptus species. The system of functions...
Tipo: Journal article Palavras-chave: Eucalyptus; Models; Timber products estimates; Volume-ratio functions.
Ano: 2010 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-16202010000100001
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An equation to determine demand constrained pasture restoration area. Repositório Alice
BARIONI, L. G.; SILVA, R. de O..
The objective of this work is to develop an equation to determine pasture restoration area based on beef demand and to use it to analyze the responses of pasture restoration to their conditioning factors in the Brazilian context.
Tipo: Artigo em anais de congresso (ALICE) Palavras-chave: Restauração de pastagem; Modelagem; Gado de corte; Beef cattle; Pastures; Models.
Ano: 2016
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An Immune System Perspective on Ecosystem Management Ecology and Society
Janssen, Marco A; Indiana University; maajanss@indiana.edu.
A new perspective for studying the complex interactions between human activities and ecosystems is proposed. It is argued that biological immune systems share a number of similarities with ecological economic systems in terms of function. These similarities include the system's ability to recognize harmful invasions, design measures to control and destroy these invasions, and remember successful response strategies. Studying both the similarities and the differences between immune systems and ecological economic systems can provide new insights on ecosystem management.
Tipo: Peer-Reviewed Reports Palavras-chave: Adaptive systems; Artificial immune systems; Biological invasions; Ecological economic systems; Ecosystem management; Immune systems; Institutions; Models.
Ano: 2001
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Analyse de la variabilité spatio-temporelle des populations phytoplanctoniques observées dans le réseau national de surveillance du phytoplancton dans le golfe de Gabés OceanDocs
Feki-Sahnoun, W..
Le long des côtes du golfe de Gabès, les données collectées dans le cadre du Réseau de Surveillance du Phytoplancton et des Phycotoxines (REPHY), constituent une base pertinente pour examiner la structure et la dynamique des communautés phytoplanctoniques à grandes échelles temporelle (1997-2007) et géographique (l’ensemble de littoral du golfe). S’appuyant sur les données du REPHY, l’objectif de cette étude était de décrire les principales formes de variabilité des communautés phytoplanctoniques observées sur nos côtes. Les schémas de la variabilité des populations phytoplanctoniques ont été examinés à différentes échelles temporelles et géographiques à l’aide de méthodes statistiques multivariées. Dans un premier temps, l’analyse de la dynamique des...
Tipo: Theses and Dissertations Palavras-chave: Phytoplankton; Temporal variations; Geographical distribution; Statistical analysis; Models.
Ano: 2013 URL: http://hdl.handle.net/1834/5444
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Aplicação do modelo computacional CropSyst na estimativa de biomassa da cana-de-açúcar. Repositório Alice
OLIVEIRA, K. R. de; CASTRO, A. de..
2013
Tipo: Resumo em anais de congresso (ALICE) Palavras-chave: Modelo computacional; Biomassa da cana-de-açúcar; Models; Sugarcane; Biomass.
Ano: 2013 URL: http://www.alice.cnptia.embrapa.br/handle/doc/981978
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