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| Registros recuperados: 122 | |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| Aubone, A.; Wöhler, O.C.. |
| With the purpose of easening its application, the theory of parameter estimation by the maximum likelihood method is presented. The theory is general and useful for linear and nonlinear models. The method is applied to the von Bertalanffy´s growth model for individual data and for mean values of length-at-age. Statistical tests to compare parameters from different population groups are presented. Problems caused by lack of verification of assumptions are discussed. An example of its application is given and results of nonlinear least squares estimations are compared to those obtained with Allen´s method. An example of application implemented on a calculus spreadsheet is attached. |
| Tipo: Journal Contribution |
Palavras-chave: Growth curves; Mathematical models; Mathematical models; Http://aims.fao.org/aos/agrovoc/c_24199. |
| Ano: 2000 |
URL: http://hdl.handle.net/1834/2541 |
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| Lima,Máida Cynthia Duca de; Barreto-Garcia,Patrícia Anjos Bittencourt; Sanquetta,Carlos Roberto; Novaes,Adalberto Brito de; Melo,Lara Clímaco de. |
| ABSTRACT: There is a large number of studies evaluating methods to quantify biomass for the genus Pinus in different regions of Brazil. However, knowledge about this subject in the Northeast region of Brazil is still incipient. The objective of the present study was to assess the biomass and carbon stocks and select mathematical models to estimate these variables in Pinus caribaea var. hondurensis , which is established in homogenous stands in the Southwest region of the state of Bahia (Brazil). The biomass was quantified using the destructive method. Samples of needles, bole, bark, and branches were analyzed to determine their carbon contents. Ten models were tested, and the best of them were chosen based on the following statistical indicators: adjusted... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Exotic forest species; Mathematical models; Biomass. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782016000600957 |
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| Hinckley, Sarah; Parada, Carolina; Horne, John K.; Mazur, Michael; Woillez, Mathieu. |
| Biophysical individual-based models (IBMs) have been used to study aspects of early life history of marine fishes such as recruitment, connectivity of spawning and nursery areas, and marine reserve design. However, there is no consistent approach to validating the spatial outputs of these models. In this study, we hope to rectify this gap. We document additions to an existing individual-based biophysical model for Alaska walleye pollock (Gadus chalcogrammus), some simulations made with this model and methods that were used to describe and compare spatial output of the model versus field data derived from ichthyoplankton surveys in the Gulf of Alaska. We used visual methods (e.g. distributional centroids with directional ellipses), several indices (such as... |
| Tipo: Text |
Palavras-chave: Mathematical models; Statistical analysis; Marine fish; Spatial distributions; Spatial analysis; Individual-based models; USA gulf of alaska; Walleye pollock. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00327/43775/43332.pdf |
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| Salomon, J. |
| The movement of water particles in the ocean and littoral zone can be thought of as the result of elementary components superimposed, of which tidal flow is the main factor. Hydrodynamical equations show that these movements are more coupled in the coastal zone than in deep ocean. This characteristic is the result of current intensity, spatial gradients and bottom topography (depth). In the coastal environment tidal flow must be taken into account to study dynamic processes. The tide is not only an alternative movement but is the inducer of a long term current: the residual current. The author uses a bidimensional model to study currents from the depth and vertical structure of residual currents by the effect of density variations. |
| Tipo: Text |
Palavras-chave: Density gradients; Mathematical models; Current prediction; Residual flow; Tidal currents; Lagrangian current measurement; Water circulation. |
| Ano: 1985 |
URL: http://archimer.ifremer.fr/doc/1985/acte-1258.pdf |
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| Siqueira, Valdiney Cambuy; Universidade Federal de Lavras; Resende, Osvaldo; Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde; Chaves, Tarcísio Honório; Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde. |
| The objective of this study was to determine the geometric diameter of volumetric shrinkage in Jatropha seeds subjected to drying under six air conditions and to fit different mathematical models to the experimental values. Seeds with an approximate initial moisture content of 0.61 kgw kgdm-1 (kilogram of water per kilogram of dry matter) were dried in a convection oven at temperatures of 36, 45, 60, 75, 90, and 105°C until they reached a moisture content of 0.11 ± 0.006 kgw kgdm-1. The experimental data were fitted to five mathematical models used to represent volumetric shrinkage in agricultural products. The models were analyzed using the coefficient of determination, chi-square, mean relative error, mean estimated error, and residual distribution.... |
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Palavras-chave: Mathematical models; Moisture content; Polynomial model. |
| Ano: 2012 |
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/14402 |
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| Registros recuperados: 122 | |
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