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Registros recuperados: 38
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Adult sex ratio effects on male survivorship of Drosophila melanogaster Meigen (Diptera, Drosophilidae) Rev. Bras. entomol.
Costa,Marcelo; Mateus,Rogério Pincela; Moura,Mauricio Osvaldo; Machado,Luciana Paes de Barros.
The behavioral biology has a central role in evolutionary biology mainly because the antagonistic relations that occur in the sexual reproduction. One involves the effect of reproduction on the future life expectation. In this scenario, changes in male operational sex ratio could lead to an increase in mortality due to costs associated with excessive courtship and mating displays. Thus, this work experimentally altered the male sex ratio of Drosophila melanogaster Meigen, 1830, to determine its impact on mortality. The results indicated that mortality increases as the sex ratio changes, including modifications in the survivorship curve type and in the curve concavity, measured by entropy.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Adult sex ratio; Entropy; Survivor.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0085-56262010000300015
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Agricultural Export Diversification in Latin America and the Caribbean AgEcon
Taylor, Timothy G.; Francis, Brian.
Agriculture, in general, and agricultural exports in particular, have long been critical to economic growth and development in Latin America and the Caribbean (LAC). Despite the importance of agriculture to the region and the vast amount of resources devoted to the promotion of agricultural export diversification in LAC, there has been virtually no research undertaken to assess the degree to which the agricultural export structures in LAC countries have in fact diversified. Using disaggregate data on agricultural exports over the 1961-2000 period for 10 LAC countries, entropy-based measures of diversification are computed and analyzed. The empirical results show that the post-1985 period has witnessed some degree of agricultural export diversification...
Tipo: Journal Article Palavras-chave: Agriculture; Caribbean; Diversification; Entropy; Exports; Latin America.
Ano: 2003 URL: http://purl.umn.edu/43284
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AN EXAMINATION OF TRENDS IN GEOGRAPHIC CONCENTRATION IN U.S. HOG PRODUCTION, 1974-96 AgEcon
Hubbell, Bryan J.; Welsh, Rick.
Geographic concentration in U.S. hog production from 1974-96 is investigated using a measure based on Theil's entropy index. For the U.S. as a whole, geographic concentration is occurring at a slow rate, both for hog farms and hog numbers. However, for particular states, primarily in the new Southern Atlantic production region, concentration is high and increasing at a rapid pace. Concentration was increasing for the 23-year period for 16 out of the 20 states in the analysis. Results indicate that geographic concentration by augmentation is occurring to the greatest degree in Arkansas, Missouri, North Carolina, Oklahoma, and Pennsylvania.
Tipo: Journal Article Palavras-chave: Entropy; Geographic concentration; Hog production; Livestock Production/Industries.
Ano: 1998 URL: http://purl.umn.edu/15566
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An information based sample-selection estimation model of agricultural workers' choice between piece-rate and hourly work AgEcon
Golan, Amos; Moretti, Enrico; Perloff, Jeffrey M..
This paper presents a new generalized maximum entropy (GME) approach to estimation of sample-selection models with small data sets, such as are found in many empirical agricultural economic analysis. For small samples, the GME approach produces more stable estimates and has smaller mean square error measures than other well-known estimators such as ordinary least squares, Heckman's two-step method, full-information maximum likelihood, and Ahn and Powell's method. The technique is used to analyze whether hired agricultural workers will work in piece-rate or time-rate jobs and to compare female-male wage differentials for both types of jobs.
Tipo: Working or Discussion Paper Palavras-chave: Agricultural labor; Agricultural wages; Data analysis; Entropy; Monte carlo analysis; Piece rates; Labor and Human Capital.
Ano: 1998 URL: http://purl.umn.edu/47285
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Análise de sobrevivência e estimativa de entropia para Sarconesia chlorogaster (Wiedemann) (Diptera, Calliphoridae) Zoologia
Moura,Maurício O.; Bonatto,Sionei R..
The life expectancy of Sarconesia chlorogaster (Wiedemann, 1830) reared in artificial diet and controlled temperatures chamber set at 27±1oC, 70±10% RH and 12 hours of photophase was analysed using entropy (H). Entropy (H) was used to quantify the distribuition of deaths between ages and then quantify the impact of mortality on life expectancy. The entropy values obtained for males (H=0,245) and females (H=0,299) were intermediary between the theoretical values of H=0,5 and H=0 suggesting a tendency toward rectangular distribuitions in both sexes. The effect of mortality across ali ages on expectation of life was different at each age. For males the highest values were found between days 10 and 20 and between days 15 and 25 for females. This íindings imply...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Diptera; Calliphoridae; Sarconesia chlorogaster; Entropy; Life expectation; Survivorship curves.
Ano: 1999 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-81751999000500013
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ASSESSING THE SPATIAL DISTRIBUTION OF CROP PRODUCTION USING A GENERALIZED CROSS-ENTROPY APPROACH AgEcon
You, Liangzhi; Wood, Stanley.
While agricultural production statistics are reported on a geopolitical – often national - basis we often need to know the status of production or productivity within specific sub-regions, watersheds, or agro-ecological zones. Such re-aggregations are typically made using expert judgments or simple area-weighting rules. We describe a new, entropy-based approach to making spatially disaggregated assessments of the distribution of crop production. Using this approach tabular crop production statistics are blended judiciously with an array of other secondary data to assess the production of specific crops within individual ‘pixels’ – typically 25 to 100 square kilometers in size. The information utilized includes crop production statistics, farming system...
Tipo: Working or Discussion Paper Palavras-chave: Entropy; Cross entropy; Remote sensing; Spatial allocation; Production; Crop distribution; Crop Production/Industries.
Ano: 2004 URL: http://purl.umn.edu/60324
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Bits and q-bits as versatility measures Anais da ABC (AABC)
Piqueira,José R.C..
Using Shannon information theory is a common strategy to measure any kind of variability in a signal or phenomenon. Some methods were developed to adapt information entropy measures to bird song data trying to emphasize its versatility aspect. This classical approach, using the concept of bit, produces interesting results. Now, the original idea developed in this paper is to use the quantum information theory and the quantum bit (q-bit) concept in order to provide a more complete vision of the experimental results.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Bit; Complexity; Entropy; Q-bit; Measure; Versatility.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652004000200035
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Curva de sobrevivência e estimativa de entropia em Lucilia cuprina (Diptera, Calliphoridae) Iheringia, Sér. Zool.
Fernandes,Francely M.; Lapola,David M.; Neregato,Rodrigo; Carvalho,Marcelo H. de; Von Zuben,Claudio J..
Lucilia cuprina (Wiedemann, 1830) is a cosmopolite blowfly species of medical and veterinary importance because it produces myiasis, mainly in ovine. In order to evaluate the demographic characteristics of this species, survivorship curves for 327 adult males and 323 adult females, from generation F1 maintained under experimental conditions, were obtained. Entropy was utilized as the estimator of the survival pattern to quantify the mortality distribution of individuals as a function of age. The entropy values 0.216 (males) and 0.303 (females) were obtained. These results denote that, considering the survivorship interval until the death of the last individual for each sex, the males present a tendency of mortality in more advanced age intervals, in...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Survivorship curve; Entropy; Lucilia; Calliphoridae.
Ano: 2003 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212003000300010
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Determinism, chaos, self-organization and entropy Anais da ABC (AABC)
PONTES,JOSÉ.
ABSTRACT We discuss two changes of paradigms that occurred in science along the XXth century: the end of the mechanist determinism, and the end of the apparent incompatibility between biology, where emergence of order is law, and physics, postulating a progressive loss of order in natural systems. We recognize today that three mechanisms play a major role in the building of order: the nonlinear nature of most evolution laws, along with distance to equilibrium, and with the new paradigm, that emerged in the last forty years, as we recognize that networks present collective order properties not found in the individual nodes. We also address the result presented by Blumenfeld (L.A. Blumenfeld, Problems of Biological Physics, Springer, Berlin, 1981) showing...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Chaos; Dynamical systems; Entropy; Evolution of Science; Pattern formation; Theoretical biology.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000301151
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ENTROPY-BASED SEEMINGLY UNRELATED REGRESSION AgEcon
Harmon, Alice; Preckel, Paul V.; Eales, James S..
We adapt the classical SUR procedure to a minimum cross entropy approach to estimate linear systems of equations where the errors across equations are correlated. We conclude that our entropy-based approach may provide a reasonable substitute for SUR in cases where classical methods may not be applied due to shortages of data.
Tipo: Working or Discussion Paper Palavras-chave: Entropy; Econometrics; Seemingly unrelated regression; Research Methods/ Statistical Methods.
Ano: 1998 URL: http://purl.umn.edu/28682
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Estimating input allocation for farm supply models AgEcon
Gocht, Alexander.
When building an economic model for supply analysis the aim is to model a decision making process of one or more agents which fits the observed practice as good as possible. Hereby the modeller is often confronted with incomplete information about the production process; particular crop specific input data are rarely available. The problem of defining activity related technology inputs coefficients is not new. A good deal of literature comes from the mathematical programming perspective, where input coefficients were estimated using a standard linear regression function to fully represent the mathematical program. However this approach is a pure technical device and may result in an inconsistent model. The author of the paper wants to investigate whether...
Tipo: Conference Paper or Presentation Palavras-chave: Farm supply model; Input allocation; Entropy; HDP; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/6469
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Estimating the size distribution of firms using government summary statistics AgEcon
Golan, Amos; Judge, George G.; Perloff, Jeffrey M..
Using a maximum entropy technique, we estimate the market shares of each firm in an industry using the available government summary statistics such as the four-firm concentration ratio (C4) and the Herfindahl-Hirschmann Index (HHI). We show that our technique is very effective in estimating the distribution of market shares in 20 industries. Our results provide support for the recent practice of using HHI rather than C4 as the key explanatory variable in many market power studies, if only one measure is to be used.
Tipo: Working or Discussion Paper Palavras-chave: Business; Entropy; Industry size; Marketing; Probabilities; Statistics; Agribusiness.
Ano: 1995 URL: http://purl.umn.edu/47276
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GAB model and the thermodynamic properties of moisture sorption in soursop fruit powder Rev. Ciênc. Agron.
Baptestini,Fernanda Machado; Corrêa,Paulo Cesar; Ramos,Afonso Mota; Junqueira,Mateus da Silva; Zaidan,Iasmine Ramos.
ABSTRACT The aim of this study was to model and determine the thermodynamic properties of moisture sorption in soursop fruit powder. The isotherms were determined by the static method at temperatures of 10, 20, 30, 40 and 50 °C, and a water activity of between 0.113 and 0.868 (decimal). The GAB model effectively described the moisture sorption phenomenon of soursop powder. The monolayer moisture content ranged from 12.589 to 9.109% db. The enthalpy values related to the GAB model were negative, with -2581.035 kJ kg-1 for C0 and -107,758 kJ kg-1 for K0. The isosteric heat of sorption, entropy and Gibbs free energy had a high correlation with the equilibrium moisture content, and the correlation between enthalpy and entropy was confirmed for moisture...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Monolayer; Entropy; Gibbs free energy; Annona muricata L.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902020000100401
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GAMS CODE FOR ESTIMATING A SOCIAL ACCOUNTING MATRIX (SAM) USING CROSS ENTROPY (CE) METHODS AgEcon
Robinson, Sherman; El-Said, Moataz.
This paper documents the computer code implementing the CE-SAM estimation technique in GAMS (General Algebraic Modeling System). It defines the estimation problem in a deterministic setting; extends the approach to include a stochastic treatment of errors in control totals; summarizes the equations describing CE technique for estimating a consistent SAM starting from an inconsistent data set estimated with error; and provides the GAMS code.
Tipo: Working or Discussion Paper Palavras-chave: Entropy; Cross entropy; Social accounting matrices; SAM; GAMS; Research Methods/ Statistical Methods.
Ano: 2000 URL: http://purl.umn.edu/16293
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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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Hyper-production of a thermotolerant β-xylosidase by a deoxy-D-glucose and cycloheximide resistant mutant derivative of Kluyveromyces marxianus PPY 125 Electron. J. Biotechnol.
Rajoka,Muhammad Ibrahim; Khan,Sana.
Production of β-xylosidaseby a cycloheximide and 2-deoxy-D-glucose-resistant mutant of Kluyveromyces marxianus PPY125 was studied when cultured on growth media containing galactose, glucose, xylose, cellobiose, sucrose and lactose as carbon sources. Xylose, cellobiose, lactose and sucrose were the key substrates. Both K. marxianus PPY125 and its mutant (M 125) supported maximum β-xylosidase specific product yield (Y P/X) following growth on xylose. Basal level of activity was observed in non-induced cultures grown on glucose. The mutant produced 1.5 to 2-fold more β-xylosidase than that produced by the wild cells. Synthesis of β-xylosidase was regulated by an induction mechanism in both wild and mutant cells. Addition of...
Tipo: Journal article Palavras-chave: Enthalpy; Entropy; Enzyme kinetics; Fermentation; Induction; Thermodynamics.
Ano: 2005 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582005000200007
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Hysteresis and thermodynamic properties of water sorption in ‘Malagueta’ pepper seeds AGRIAMBI
Silva,Hellismar W. da; Rodovalho,Renato S.; Silva,Isneider L..
ABSTRACT The objective of this study was to determine hysteresis, enthalpy, entropy, enthalpy-entropy compensation theory and Gibbs free energy for water adsorption and desorption in ‘Malagueta’ pepper seeds. Hygroscopic equilibrium moisture contents were determined by the static gravimetric method, with water activity in the range from 0.29 to 0.90 and temperatures of 30, 40 and 50 °C. The hysteresis of the ‘Malagueta’ pepper seeds reduces with the increase of temperature. Enthalpy, entropy and Gibbs free energy of adsorption and desorption increase with the reduction of the moisture content of the seeds. The enthalpy-entropy compensation theory is valid for the sorption processes. The sorption of water between seeds and the surrounding air is a...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Capsicum frutescens L.; Enthalpy; Entropy; Gibbs free energy.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662018000900658
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Industrial specialisation and geographic concentration: Two sides of the same coin? Not for the European Union AgEcon
Aiginger, Karl; Davies, Stephen W..
Some recent studies have shown that specialisation of countries has tended to increase, while regional concentration of countries has tended to decrease. This seems to be counterintuitive at first glance. In this paper, we use the entropy index - as the indicator of structural change with the neatest aggregation properties to show how this divergence can happen. The main purpose of the paper is methodological, but we also apply the methodology to a specific case study: Manufacturing in the European Union since 1985. We confirm for this interesting period that increasing industrial specialisation has been offset by faster growth in the smaller Member States, with the net effect that industries have become somewhat less geographically concentrated. In terms...
Tipo: Journal Article Palavras-chave: Structural change; Geographical concentration; Industrial specialisation; European integration; Entropy; F02; F15; L60.
Ano: 2004 URL: http://purl.umn.edu/37627
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Informed Control Over Inputs and Extent of Industrial Processing AgEcon
Hennessy, David A..
Stylized facts regarding the industrial process include emphases on obtaining information about and control over the quality of raw materials. We provide a model that establishes conditions under which informed control involves ensuring uniformity in inputs and increased uniformity encourages more extensive processing. We show when the Boltzmann-Shannon entropy statistic is an appropriate measure of uniformity.
Tipo: Working or Discussion Paper Palavras-chave: Entropy; Homogeneous inputs; Industrialization; Information technologies; Sorting; Industrial Organization.
Ano: 2005 URL: http://purl.umn.edu/18580
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Innovation in Food Products: First-mover Strategy and Entropy Metrics AgEcon
Sporleder, Thomas L.; Hooker, Neal H.; Shanahan, Christopher J.; Broring, Stefanie.
The objective of this research is to investigate food product innovation in the context of the first-mover strategy among food manufacturers within agrifood supply chains. The emphasis of the analysis is on developing a useful metric for tracking new product development in the context of first-mover strategy. Entropy is introduced as a novel and useful means of examining first-mover strategy and new product development (NPD) in general. Understanding the complexities of the first-mover strategy and tracking NPD with entropy metrics holds promise for enhancing the analysis of agrifood supply chains and assisting firms in deciphering broad strategies of their rivals.
Tipo: Journal Article Palavras-chave: First-mover strategy; Food product innovation; Entropy; Organic; Research and Development/Tech Change/Emerging Technologies; Q10; Q16.
Ano: 2008 URL: http://purl.umn.edu/53729
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