Search

Identifying, quantifying and spatialising factors that condition water erosion processes, such as erosivity, can help to understand the process of sediment input to watercourses and, in this specific case, to hydroelectric plant reservoirs. The aim of this study was to estimate and spatialise rainfall and erosivity indices in the Area of Direct Influence (AID) of the Batalha reservoir (GO/MG). Using the database provided by the National Water Agency's (ANA) HIDROWEB portal, the equation proposed Silva et al. (1997) was adopted, and to measure the accuracy of the erosivity estimation models, the Fournier index (1958) was adopted for rainfall in the region, for a historical series from 1991 to 2021. To do this, the estimates took into account monthly and annual rainfall and their spatial variability for the south-eastern regions of Goiás and north-western Minas Gerais. By means of a descriptive analysis and spatialisation of the Erosivity Index (EI), in the study of annual variability, there was a tendency for it to increase in an approximately north-south direction, towards the south and centre-south. Similarly, in the study of monthly variability, there was an increase in the EI also in an approximately north-south direction, towards the south and centre-south, in the months with the highest rainfall. It was also observed that the months with the highest rainfall, corresponding to the spring and summer seasons, had the highest Erosivity Indices, classified as high and very high, except for October. For the drier months, corresponding to autumn and winter, these indices were classified as low and very low. Overall, the average annual erosivity was classified as high. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was to study the growth curves of total dry matter (TDM) accumulation of the P30F33 and GNZ2004 maize hybrids using nonlinear models. The used models were: Brody, Gompertz, logistic, Meloun I, Meloun II, Michaelis-Menten, modified Michaelis-Menten, Mitscherlich, Richards, Schnute, von Bertalanffy, and Weibull. To estimate the parameters, the least squares method and the Gauss-Newton convergence algorithm were used. The adjusted coefficient of determination, the residual standard deviation, and the Akaike information criterion were used as criteria to evaluate the goodness of fit of the models. The Gauss-Newton method did not converge for 8 out of the 12 models studied. The Gompertz, logistic, von Bertalanffy, and Weibull models were considered appropriate for fitting the dry matter accumulation of the evaluated maize hybrids. The estimated TDM was 34,700 and 31,980 kg ha−1 for GNZ2004 and P30F33, respectively. The maximum daily gain in TDM was 483 and 381 kg ha−1, respectively, reached at 83 days after emergence, with TDM stabilization at 121 and 129 days after emergence. The logistic model is the best one to describe the TDM accumulation of the GNZ2004 and P30F33 maize hybrids.

Fire Hazard (FH) modelling is a relevant fire prevention/assessment tool. This work proposes a FH model and generates a FH map for a wildland urban interface area in Germany that is not prone to extreme fires. The main input data include weather, topography, fuel, and anthropic-related potential ignition points. The main steps include (1) identification/description of weather scenarios, and for each scenario (2) analysis of potential fire ignition through simulation of Fire Probability (FP), (3) modelling the potential fire behaviour through simulation of Fireline Intensity (FLI), (4) generation of a FH map by combining FP and FLI maps, and (5) integration of all maps into a final FH map. Extreme ignition and propagation conditions were considered: (1) a fuel model that describes the fire performance in an extreme drought scenario, (2) the human influence through mechanistic ignitions, and (3) the worst case of all scenarios. As results, four weather scenarios were identified and described. FP maps, FLI maps, and FH maps were created for each of them, and finally an integrated FH map (IFHM) was derived.

Vector-borne diseases are a cause of concern all around the world, especially in Brazil. In the past few years, the Brazilian health system faced recurrent epidemics such as Dengue and Malaria as well as new cases of Chikungunya, Zika and Yellow Fever. Vector control continues to be one of the most important counter measures against these types of diseases. Mathematical models are important tools for planning vector control strategies. In this work we present an approach in order to calculate what is the minimum vector control intensity to obtain stability in a simple population’s dynamics model of mosquitoes.We combined numerical simulations with analytic results. Transcritical bifurcations appear in our analysis considering different control’s parameters values for the eggs, larvae, pupae and adults mosquitoes populations. A discussion about combined strategies of vector control was also showed.

Pressure vessels are essential industrial tools regarding storage of high-pressure fluids. Utilization of pressure vessels in ordinary industrial environment impose serious dangers to human life in case of failure. Manufacturing material and working pressure as per material’s strength are necessary arguments for a pressure vessel designer. In this study, five composite materials are selected to investigate the behavior of pressure vessels under high pressure. FEA technique is used to check stresses and deformations in different composite layers. Pressure applied to all materials models in this study is around 20 MPa. Tsai Wu and Maximum stress theories are used to study failure in first two composite layers of different composite materials. Glass Epoxy composites perform well in terms of static loading failure. They demonstrate reasonable strength without experiencing failure in the second layer. T300/976 composites are also suitable for the intended loading conditions of the model because did not exhibit second layer failure, making them a viable option. Therefore, it is recommended to use Glass/Epoxy and T300/976 composites in extreme pressure conditions such as those found in CNG cylinders. Three of the composite materials tested did not satisfy the failure theories. Hence, it is not safe to use them in extreme loading conditions. Although these materials did not show any failure in the first layer, deformations in the second layer made them susceptible to failure.

A grande quantidade de áreas degradadas e o potencial produtivo das reservas legais no Brasil tornam a restauração uma demanda ambiental e oportunidade comercial. Modelamos o crescimento do diâmetro em função da idade de oito espécies de árvores em plantações de recomposição na Amazônia brasileira. A partir de 14 anos de dados de inventário florestal anual, testamos variações da função logística: logística simples, logística com covariante (área da planta na época do plantio), logística com efeito aleatório, logística com efeito aleatório e covariante. As espécies Schizolobium parahyba var. amazonicum, Tectona grandis e Simarouba amara apresentaram as maiores taxas de crescimento, enquanto Cordia alliodora, Cedrela odorata e três espécies do gênero Handroanthus apresentaram crescimento mais lento. Os ganhos com o uso da covariante na modelagem foram pequenos para modelos de efeitos fixos e mistos. Os ganhos com a inclusão do efeito aleatório foram substanciais. Os modelos de efeitos mistos tiveram o melhor desempenho na modelagem do crescimento das espécies. Nossos resultados fornecem subsídios para uma visão crítica sobre os critérios, possibilidades de recomposição e práticas de manejo de áreas degradadas em reservas legais na Amazônia. Uma análise econômica é necessária para garantir a viabilidade da exploração sustentável dessas áreas.

Copyright of Journal of Water Resources / Recursos Hídricos is the property of Associacao Portuguesa dos Recursos Hidricos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Metaheuristic algorithms solve optimisation problems by identifying the best combination among a set of variables to enhance a function. Within metaheuristics, the main purpose of this work is that of showing the development of research issues about processes related to optimisation and metaheuristics, with a focus on the projection of those issues with greater possibility of development. Optimization processes is one of the most studied fields in artificial intelligence, optimization, logistics, and other applications The main contributions of this work were the identification of the main issues contained in the themes of process optimization and metaheuristics; an analysis of the expansion and retraction of the aforementioned theme; an understanding of convergence and divergence; and an analysis of the stages of development as presented in the gaps of the fifty most commonly mentioned articles. The main finding was to analyze the development of research topics on optimization processes and metaheuristics, focusing on projecting the topics most likely to develop.

In this paper it is presented a gentle review of empirical and theoretical advances in understanding the role of size in biological organisms. More specifically, it deals with how the energy demand, expressed by the metabolic rate, changes according to the mass of an organism. Empirical evidence suggests a power-law relation between mass and metabolic rate, namely the allometric equation. For vascular organisms, the exponent β of this power-law is smaller than one, which implies scaling economy; that is, the greater the organism is, the lesser energy per cell it demands. However, the numerical value of this exponent is a theme of extensive debate and a central issue in comparative physiology. A historical perspective is shown, beginning with the first empirical insights in the sec. 19 about scaling properties in biology, passing through the two more important theories that explain the scaling properties quantitatively. Firstly, the Rubner model considers organism surface area and heat dissipation to derive β = 2 / 3. Secondly, the West-Brown-Enquist theory explains such scaling properties due to the hierarchical and fractal nutrient distribution network, deriving β = 3 / 4.

In this article we present a compilation of research results on the educational use of Fermi problems. While working on these problems, the key aspect is identifying the most relevant variables of a phenomenon and estimating them in order to obtain a solution to the problem. Fermi problems come from a long tradition, they have been used at all educational levels, but they have not yet established as a common activity in the classroom, especially in science classrooms. Given the broad didactic potential of Fermi problems identified in the literature, our contribution in this article is the connections with areas of interest for science teaching. We propose four didactic axes to which Fermi problems can make a relevant contribution in the science classroom: (a) To better understand what science is like, (b) To better participate in school science, (c) To better construct scientific ideas, (d) To better raise awareness of socio-scientific problems. To make the proposal more concrete, we show an example of a concrete solution with a problem of estimation of energy values, which allows us to exemplify classroom work and allows discussion with students on the relevance of science in social problems. [ABSTRACT FROM AUTHOR]

In this study we present a documentary review of 50 works that offer us an opportunity to address some of the problems of education in the department of Chocó, in Colombia, where the results of the standardized tests that the Ministry of National Education carries out show that students present difficulties in the three competencies that the Saber test evaluates. On the other hand, we find a preference for the transmissionists model and for memorizing content. To address this problem, we look at two competencies: argumentation and modelling. Argumentation allows us to remove doubts about a statement and modelling has a high cognitive demand that requires, connecting and relating data and identifying regularities that allow us to model a phenomenon. The integration of these two skills into classroom practices offers an alternative to teachers for a paradigm shift in the education of students in Chocó.

Abstract: Despite the ubiquity of models in science education, there are several different conceptions about their nature in the scientific community. We sought to investigate understandings about them conveyed in the recent research in science education. To this end, we have reviewed papers published on models and modelling between 2010 and 2019. Our analysis revealed that these different notions on the concept of model could be represented in three main trends: Concrete, Construct and Mathematical. In addition, we found that these studies: are predominantly empirical in nature; involve frameworks arising mainly from science education research itself, but with a considerable influence from Philosophy of Science and cognitive sciences; encompass Physics, Biology and Chemistry domains in relatively similar frequencies, but decreasing in this order. Another outcome of this study was the emergence of different scenarios regarding the journals consulted, revealing the existence of different thought styles in science education research community.

ABSTRACT The aim of this study was to evaluate estimations of leaf area in rapeseed (Brassica napus L.) and the potential for application to different genotypes, environmental conditions and types of crop management. In experiments conducted during 2013, 2014, 2016 and 2017, three genotypes of rapeseed, five doses of nitrogen and three sowing dates were used. Leaves were randomly collected from different plants and positions on the plants. The leaf area (LA), and maximum width (W) and length (L) were determined for each leaf, and the product of L and W (LxW) was calculated. Fifty-six equations for estimating LA in rapeseed, where the independent variables were W, L or LxW, were compiled from the bibliography and evaluated in this work. The evaluation was made using the following statistics: significance of the linear (a) and angular (b) coefficients of the regression around the 1:1 line, concordance index (d), bias index (BIAS), mean absolute error (MAE), mean relative error (MRE), random mean squared error (MSEr) and systematic mean squared error (MSEs). Only 11 equations showed the a and b coefficients as not being different from 0 and 1 respectively. However, only 10 were suitable, as they displayed the lowest values for d, BIAS, MAE and RME, and the MSEs was smaller than the MSEr. The MAE ranged from 5.4 cm2 to 16.2 cm2, well within the error range for generating the equations. LA in rapeseed can be estimated by general biometric equations without considering the specificity of the genotype or the morphological type of the leaf.

The urban sprawl implies in the reduction of rural production areas and increases the pressure on the natural spaces. Hence, if the urbanization does not occur properly, it can compromise sanitary conditions, biodiversity, resources and environmental services. This paper aims at presenting a mathematical model to support urban sprawl based on population dynamics, applied as a case study in the Economic Hub of the Metropolitan Region of Sorocaba - MRS. The materials corresponded to census data and urban planning parameters of the applicable law. As a result, it was found that the urban extension of Sorocaba is oversized, and that the maintenance of the current conditions and guidelines will have critical consequences, requiring a change in local politics. We conclude that the proposed model can support strategic decisions, preventing problems related to disordered growth.

Copyright of Comunicaçõe Geológicas is the property of Laboratorio Nacional de Energia e Geologia, I.P. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A recurring problem in longitudinal research on human activity is the lack of articulation between qualitative analytical models and quantitative synthetic models of the dynamic evolution. This absence creates difficulties in justifying the choices of analysis and synthesis and prevents a deductive approach to longitudinal dynamics. Within the framework of a 3-year longitudinal empirical and technological research on appropriation, this paper discusses the conditions of production and the usefulness of a quantitative synthetic model of the longitudinal complexity of individual activity, in conjunction with a qualitative analytical method. More than the mobilization of a single, pre-data model, the modeling work involves an active articulation between analytical model-methods (classical in activity analysis) and synthetic model-methods. We discuss the contributions and limits of this work with respect to activity analysis in French-language ergonomics and the complexity sciences more often mobilized in human factors.

The digital models of landform representation allow several types of geomorphological analysis, such as assessing prone areas to the mass movement. Among the data set that applied to elaborate such models, LiDAR (Light Detection and Ranging) technology has stood out due to its capacity to represent in detail terrain specific characteristics. This work aimed to present a variety of studies based on LiDAR to evaluate slope instability and to describe an interpolation test of LiDAR raw data to generate a Digital Terrain Model considering different interpolation approaches, in an area affected by shallow landslides. The results show that the tool applied is efficient when combined Triangulation to Natural Neighbor methods.

A recurring problem in longitudinal research on human activity is the lack of articulation between qualitative analytical models and quantitative synthetic models of the dynamic evolution. This absence creates difficulties in justifying the choices of analysis and synthesis and prevents a deductive approach to longitudinal dynamics. Within the framework of a 3-year longitudinal empirical and technological research on appropriation, this paper discusses the conditions of production and the usefulness of a quantitative synthetic model of the longitudinal complexity of individual activity, in conjunction with a qualitative analytical method. More than the mobilization of a single, pre-data model, the modeling work involves an active articulation between analytical model-methods (classical in activity analysis) and synthetic model-methods. We discuss the contributions and limits of this work with respect to activity analysis in Frenchlanguage ergonomics and the complexity sciences more often mobilized in human factors. [ABSTRACT FROM AUTHOR]

Should terminal station operators take steps against terrorist events by developing security checks or should they rely on open transit systems and smooth pedestrian flows as key factors of security prevention? The authors argue that the necessity to articulate fluidity and security strategies in saturated transport places necessitates a careful approach of the spatial insertion of passenger flow as well as a contextual - and critical - perspective of security governance in stations. The demonstration is developed in two stages. Based on a worldwide census and a critical analysis of these events, this article makes a clear correlation between the increase of terrorist attacks in railway stations and the installation of boarding controls. The study of the different positions of these security devices gives a typology of possible access control perimeters. The case of Paris Nord Station boarding controls is then studied in more detail. There, the security gates destabilise boarding and circulation to the point that they are regularly neutralised in order to limit the crowding problems they create. Yet, the devices remain in place since 2015 Thalys attacks for their performing value and because of the State will make visible and enact a permanent defence to terrorist risk, through space.

ABSTRACT: Leaf hyperspectral reflectance has been used to estimate nutrient concentrations in plants in narrow bands of the electromagnetic spectrum. The aim of this study was to estimate leaf nutrient concentrations using leaf hyperspectral reflectance and verify the variable selection methods using the partial least squares regression (PLSR). Two studies were carried out using stands with Eucalyptus clones. Study I was established in Eucalyptus stands with three clones, classifying leaves into five colour patterns using the Munsell chart for plant tissues. Immediately after leaf collection, leaf reflectance was read and the chemical analysis was performed. Study II was carried out in commercial clonal stands of Eucalyptus performing the same leaf sampling and chemical analysis as used in Study I. All leaf reflectance spectra were smoothed and three more pre-processing procedures were applied. In addition, three methods of PLSR were tested. The first derivative was more accurate for predicting nitrogen ( R c v 2 = 0.95), phosphorous ( R c v 2 = 0.93), and sulphur concentration ( R c v 2 = 0.85). The estimates for concentrations of calcium ( R c v 2 = 0.81), magnesium ( R c v 2 = 0.22), and potassium ( R c v 2 = 0.76) were more accurate using the logarithm transformation. Only the estimates for iron concentrations were performed with higher accuracy ( R c v 2 = 0.35) using the smoothed reflectance. The copper concentrations were more accurate ( R c v 2 = 0.78) using the logarithm transformation. Concentrations of boron ( R c v 2 = 0.68) and manganese ( R c v 2 = 0.79) were more accurate using the first derivative, while zinc ( R c v 2 = 0.31) concentration was most accurate using the second derivative.

ABSTRACT The Amazon forest comprises many different forest types, amongst them are campinas and campinaranas, which occur on Amazonian sandy soils, representing 2.65% of Amazonian territory. An understanding of the ecology and quantification of the environmental goods and services of campinaranas is key to their conservation. Based on a direct method to estimate biomass and carbon content of campinarana, we harvested and weighted 89 trees and other forest components in ten randomly allocated plots of 100 m2 (10 x 10 m) and 11 additional trees outside the plots. The data allowed us to describe how biomass is distributed amongst campinarana vegetation and amongst tree compartments. We developed allometric equations to estimate the total, above- and below-ground biomass and carbon stock of this forest type. We used a Weibull function to test if the diameter distribution of the individual trees sampled was consistent with the diameter distribution of the forest type. We also tested if terra-firme forest biomass equations could be used to estimate campinarana biomass, and whether a correction factor based on dominant height would reduce the error from these estimates. Allometric equations are considered to be the most reliable and rapid method for calculating forest biomass, and are used in forest management and climate change studies. These are the first total biomass equations developed for central Amazonian campinaranas. The best fitted allometric equation for total fresh biomass was: ln (Total Biomass) = -1.373 + 2.546 * ln DBH (R ² = 0.98, Sxy% = 4.19%).

This work assessed and compared the leaching properties of two types of compost and stabilized waste from a mechanical-biological treatment (MBT) plant. The first type of compost and the MBT waste were produced by aerobic treatments, while the second type of compost was generated from a combination of anaerobic and aerobic biodegradation processes. Both static-batch leaching tests, carried out applying a single liquid to solid (L/S) ratio equal to 10 L kg-1, and dynamic column percolation tests, investigating constituents release as a function of different L/S ratios, were performed. The three materials were also characterized in order to investigate their biological stability degree, organic matter content, and metals total content. As expected, due to the differences in feed input waste or treatment conditions, the three types of samples showed different characteristics and leaching concentrations. However, the leaching behavior of the three types of treated materials presented similar trends of dissolved organic carbon (DOC) and metals (Cu, Ni, Pb, Zn) leaching as a function of the L/S ratio. A screening model proposed and developed for MBT waste in a previous study, which allows the description DOC release as a function of the L/S ratio, was applied and discussed. The comparison of model predictions with the experimental leaching data highlighted that for all three samples the screening model describes quite well the release trends of metals.

Copyright of Revista Electrónica de Enseñanza de las Ciencias is the property of Revista Electronica de Ensenanza de las Ciencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we analyze the problem of separating two interleaved phone books, and propose an alternative configuration that is equivalent to removing their spines. We show theoretically and experimentally that even in that configuration the separation of the phone books may require a lot of force. [ABSTRACT FROM AUTHOR]

Copyright of Revista Góndola, Enseñanza y Aprendizaje de las Ciencias is the property of Gondola, Ensenanza y Aprendizaje de las Ciencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The objective of this work was to estimate the coffee supply by calibrating statistical models with economic and climatic variables for the main producing regions of the state of São Paulo, Brazil. The regions were Batatais, Caconde, Cássia dos Coqueiros, Cristais Paulista, Espírito Santo do Pinhal, Marília, Mococa, and Osvaldo Cruz. Data on coffee supply, economic variables (rural credit, rural agricultural credit, and production value), and climatic variables (air temperature, rainfall, potential evapotranspiration, water deficit, and water surplus) for each region, during the period from 2000-2014, were used. The models were calibrated using multiple linear regression, and all possible combinations were tested for selecting the variables. Coffee supply was the dependent variable, and the other ones were considered independent. The accuracy and precision of the models were assessed by the mean absolute percentage error and the adjusted coefficient of determination, respectively. The variables that most affect coffee supply are production value and air temperature. Coffee supply can be estimated with multiple linear regressions using economic and climatic variables. The most accurate models are those calibrated to estimate coffee supply for the regions of Cássia dos Coqueiros and Osvaldo Cruz.

The Pearl millet (Pennisetum glaucum) is an annual cycle grass, characterized by its low cost of production, high nutritional quality and multiplicity of uses. The objective was to find optimal conditions of plant height, stem diameter and length of millet submitted to saline stress through the response surface methodology. It was verified that the point that maximized the height (192.81 cm) of millet plant was given by CEa of 1.8 dS m-1 (salinity) and a plant age of 45.8 days. The highest length (143.7 cm) and stem diameter (13.05 cm) of millet were defined by CEa of 1.8 and 2.47 dS m-1 and ages of 43.47 and 31.78 days, respectively. Response surface analysis is promising to evaluate the maximum plant height, lenght and stem diameter of millet. The degree of salinity of the irrigation water that maximizes plant height, length and stem diameter of millet its between 1.8 and 2.66 dS m-1 of electrical conductivity. [ABSTRACT FROM AUTHOR]

The creation of quails for egg production is expanding in the last years, being a good alternative for nutritional quality of population. The great demand for high quality eggs involves the production process with relevance in the characteristics of weight, color, shell integrity and uniformity. To explain the percentage of laying of european quails fed with different lysine levels, the beta regression model was used. The beta regression model is used to model rates and proportions as in the case of posture of the birds. After adjustment, the model presented explanatory power of 96.61%, and identified as explanatory variables for the percentage of postures of the quails lysine level inserted in the diet, number of eggs per birds housed, feed conversion and lysine consumption. It was observed that at each increment of lysine level, a 29.3% increase in the percentage of posture is expected, since at each increment of the number of eggs per bird housed this rate is 56.5%, while for each increase in feed conversion and in lysine consumption respectively, a decrease of 0.3% in the percentage of laying of quails. The beta regression model was very effective when compared to models usually employed in modeling of the European quail laying percentage. [ABSTRACT FROM AUTHOR]

This study is based on the technique Interpretive Structural Modelling (ISM), in order to delineate a flowchart that shows the main ten barriers (and their relationships) influencing the development of Portuguese Entrepreneurship Ecosystem. Through a process of modelling it was possible to reach a graphical representation that shows the operating sequence of these barriers in order to understand the logic of their relationship. The results show a model represented by a flowchart consisting of 10 barriers, three of them that are positioned at the base of the model have political-legislative features with high level of range in all the remaining barriers, so a political involvement, carefully measured, could contribute to the improvement of the Portuguese Entrepreneurship Ecosystem. The final model is a useful tool that can be adopted by key decisionmakers and players in the Ecosystem in order to optimize the selection of measures enabling the entrepreneurial activity in Portugal.

Copyright of Bitácora Urbano/Territorial is the property of Bitacora Urbano/Territorial and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Little is known about the toxicity of concomitantly occurring mycotoxins in pig diets. This study was conducted to evaluate, through meta-analysis, the individual and the combined effects of mycotoxins on pig performance. The meta-analysis followed three sequential analyses (graphical, correlation, and variance-covariance) based on a database composed of 85 published papers, 1,012 treatments and 13,196 animals. Contamination of diets with individual mycotoxins reduced (p < 0.05) feed intake by 14 % and weight gain by 17 %, while combined mycotoxins reduced the same responses by 42 % and 45 %, respectively, in comparison with the non-challenged group. The correlation (p < 0.05) between reduction in weight gain (ΔG) and reduction in feed intake (ΔFI) was 0.67 in individual challenges and 0.93 in combined challenges. The estimated ΔG was –6 % in individual challenges and –7 % in combined challenges when ΔFI was zero, suggesting an increase in the maintenance requirements of challenged animals. Most of ΔG (58 % in individual challenges and 84 % in combined challenges) was attributed to the changes in feed efficiency. The association of mycotoxins enhances individual toxic effects and the ΔFI is important in explaining the deleterious effects on the growth of challenged pigs.

This article investigates the concept of graphical argumentation as an exercise of essayistic prose developed in the process of writing expansion in printed texts. It is understood that by expanding the scope of the word in the context of visual graphics processes such as drawings, photography and infographics, arguments are achievements much more of diagrammatic reasoning than of rhetorical elaboration. Proof of that are graphic arguments, which have become an inalienable modeling from texts of scientific communication, such as the ones produced in the Pesquisa FAPESP journal.

Estimating the individual volume of trees with precision and without bias is a prerequisite of a quality forest inventory. The most common methods are based on application of the average form factor, or on single or double entry equations. This study proposes models with two diameters as independent variables to estimate the commercial volume of Tectona grandis, with a view to improving precision and reducing bias. Thirty-five trees from commercial plantation of 4-5 years old, in the town of Redenção, in the State of Pará, were rigorously cubed using the Smalian method of scaling. Diameters at different heights were correlated with actual volume. Three new volumetric models based on two diameters were proposed, without the addition of tree height as a variable. These models were compared with others, which are traditionally used in forest inventories. The model with the best fit uses the diameter at breast height (dap) and at a height of 4.0 m (d4.0) as independent variables. The operational difficulties of using d4.0 are discussed. Models that use the dap and the diameter at 2.0 m (d2.0) were considered the most satisfactory, as they are more accurate and practical than classic models, and operationally more feasible than the model using d4,0. The conclusion was that there are other diameters that are more correlated with volume than dap, and that the introduction of a second diameter improves volume estimates, even without the inclusion of height as a variable.

ABSTRACT Time series modelling applied to study water table depths monitoring data is an elegant way to model irregular and continuous data. When successive observations are dependent, future values may be predicted from past observations, and target parameters can be estimated. These may include expected values of groundwater levels, or probabilities that critical levels are exceeded at certain times or during certain periods. These target parameters are estimated with the purpose of obtaining characteristics of the development of a certain domain in time and such characteristics can, for instance, be extrapolated to future situations. In a system identification approach, is it possible to establish the dynamic relationship between water table perturbations and climatological events, vegetation, hydrogeological local conditions, management and groundwater abstraction. The aim of this work was demonstrate the use of a physical-based time series model to stablish the relationship between precipitation and water table depths from hydrogeological monitoring data. The results enabled to infer about water table dynamics even when it is affected by different climatological patterns, simulating mean, maximum and minimum states.

ABSTRACT Throughfall (TF) is influenced by different meteorological conditions, which can result in high spatial and temporal variability, when interacting with vegetation and mutually with each other. This study aimed to evaluate rainfall (RF) influence on TF, as well as to describe the behavior of these variables in an area dominated by Pinus elliottii in southeastern Brazil, by exploring different statistical models proposed in the literature. For this, RF and TF data were recorded in 24 rainfall events by 180 gauges distributed in six 10 x 10 m plots. The results indicate a significant influence of RF volume on response variables [TF volume (TFmm), TF fraction (TF%) and coefficient of variation of TF (CVTF)]. While the linear model presented the best fit for TFmm , the non-linear models had better results for TF% and CVTF as a function of RF, allowing the identification of distinct behaviors for different RF volumes. In general, it was verified that RF is the main source of variability in TF estimates in the study area. However, it should be noted that other variables may be acting simultaneously on TF% and CVTF, in which 45.4 and 38.1% of the variation, respectively, remain unexplained, requiring complementary studies to identify and quantify the influence of other factors.

There is great potential in Brazil for the cultivation of indigenous and introduced species of bamboo. However, there is little scientific research on the biometric aspects of these plants, and this may limit their management and use. The aim of this article therefore, is to present options for estimating the total apparent volume of two species of the genus Bambusa: B. oldhami i and B. vulgaris, planted in an experiment set up in December of 2008 in Pinhais, in the state of Paraná, Brazil (PR). Twenty-four stems were cubed at 50 months using the Smalian method. Diameter at breast height (DAP) ranged from 1.8 to 4.5 cm, and height from 3 to 7 m. The options being tested for estimating the apparent volume of the culms were: 1) Schumacher-Hall conventional volume model; 2) fifth-degree polynomial taper model; 3) fractional-power polynomial taper model; and 4) form factor. The options were examined statistically relative to the observed values for the target variable, for each species and for both species as a set. It was found that the four options give precise estimates. There was no statistical difference between the four approaches and the control (observed values) by paired t-test. The residuals (estimated x observed values) are shown to be homoscedastic with a maximum width of from -30 to 30%. It was concluded that the four methods under test can be used to estimate the target variable under the conditions of the experimental material. The Schumacher-Hall model represents the best compromise between simplicity and accuracy = O Brasil possui grande potencial de cultivo de espécies autóctones e introduzidas de bambu. Contudo, são poucos os trabalhos científicos que versam sobre aspectos biométricos dessas plantas, o que pode representar uma limitação para seu manejo e utilização. Assim, objetivou-se com esse artigo apresentar opções para estimativa do volume total aparente de duas espécies do gênero Bambusa: B. oldhamii e B. vulgaris , plantadas em experimento estabelecido em dezembro de 2008 em Pinhais-PR. Vinte e quatro colmos foram cubados aos 50 meses pelo método de Smalian. Os diâmetros à altura do peito -DAP variaram de 1,8 a 4,5 cm e as alturas de 3 a 7 m. As opções testadas para estimar o volume aparente dos colmos foram: 1) Modelo convencional de volume de Schumacher-Hall; 2) Modelo de afilamento polinomial de 5 o grau; 3) Modelo de afilamento polinomial de potência fracionária; e 4) Fator de forma. As opções foram examinadas estatisticamente em relação aos valores observados da variável de interesse para cada espécie e para o conjunto de ambas. Verificou-se que as quatro opções proporcionam estimativas precisas. Não houve diferença estatística entre as quatro abordagens em relação à testemunha (valores observados) pelo teste t pareado. Os resíduos (valores observados x estimados) se mostram homocedásticos, com amplitude máxima de -30 a 30%. Concluiu-se que os quatro métodos avaliados podem ser utilizados para estimar a variável de interesse nas condições do material experimental. O modelo de Schumacher-Hall representa o melhor compromisso entre simplicidade e acurácia.

Copyright of Galician Journal of Economics / Revista Galega de Economía is the property of Universidad de Santiago de Compostela, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Producao Online is the property of Associacao Brasileira de Engenharia de Producao and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In Physics teaching, especially when the topics of Mechanics are addressed, there are several situations about masses linked by springs, in which springs are considered to have negligible mass with simplifying purposes. We present a study on the conceptualizations, from the dynamic and energetic points of view, achieved by university students who study scientific and technological careers, about this modelling. From the unpromising results obtained, we inquired, about the treatment of this idealization in Physics textbooks frequently used in the initial cycle, in which we researched if the physical consequences of considering springs massless are properly explained by the authors. From the results achieved we consider that establishing links between this idealization, and applying laws and physical principles when addressing problem situations may not be immediate for students; and, on the other hand, we found that not all the authors presented sufficient explanations about this simplifying assumption. Recommendations for teachers are mentioned. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine growth curves and body nutrients deposition by using Gompertz equation, and to estimate protein requirement in light and semi heavy hen pullets. In total, 1,500 hen pullets were distributed at random into 30 repetitions of 25 birds each. Experimental period was divided into three steps (1st to 4th, 5th to 11th and 12th to 16th weeks of age). Rations were formulated based on corn and soybean meal and offered ad libitum. Birds were weighed weekly. Two birds per repetition were used to determine chemical body composition and data were used to obtain Gompertz model parameters. Allometric ratios were used to describe changes in the body composition in protein, lipid, mineral matter and water in the eviscerated and featherless body. Weight-age data of Dekalb White and Bovans Goldline pullets were well described by Gompertz function. Allometric coefficients of fat, water and mineral matter in function of the protein body weight were, respectively: 0.114, 0.811 and 0.930 for Dekalb line and 1.160, 0.429 and 0.189 for Bovans line. There are differences between lines for growth rates and body nutrients and feathers deposition, with Dekalb line being the most precocious. Total protein requirements (maintenance and growth) for pullets from 1st to 4th, 5th to 11th and 12th to 16th weeks of age were 4.41; 9.814 and 12.612 g·d-1 for Dekalb White and 4.82; 8.859 and 7.673 g·d-1 for Bovans Goldline, respectively. [ABSTRACT FROM AUTHOR]

In this paper we present an outline of an ongoing research in which we intend to investigate on the teaching of the modelling process and families of functions in the context of a course in Economics and Management. Specifically, we introduce some of the theoretical foundations that support the research and we present an example of one of the activities that we are designing for teaching.

The existence and, if applicable, the location of paths with given properties is a topic in graph theory. One of these problems is to find routes through all points, only once, starting and ending at the same node. This problem is known in Graph Theory as the theory of Hamilton cycles. If the concurrence of the initial and final ends is not required then we have a version of this problem known as the Hamiltonian path problem. In this article we focus on some real situation problems related to design tourist routes on a journey. Their solutions are obtained after a proper modelling. We study appropriate transformations of the graph G chosen to represent the situation so that we could determine the existence of Hamiltonian paths in the graph G and, if available, to find at least one of them from the analysis of the existence or not of Hamiltonian cycles in the new auxiliary graph G0.

We present a proposal addressed to students of the first courses of ESO. Through these activities, pupils will work concepts related with proportionality. Our proposal is developed along art history, the students will acquire skills related with proportionality through the uses the artists have done throughout history. Through a route beginning in ancient Egypt and ending in today Athens, students will act as the artists, architects or even tour guides to deal with technical problems and solve them mathematically. Some of the activities have been already implemented in the project Estalmat CV (a mathematic stimulation program for talented students) and later adapted to a conventional classroom of the first courses of ESO.