O uso de modelos no ensino de química: uma investigação acerca dos saberes construídos durante a formação inicial de professores de Química da UFRN

In the past twenty years, there has been a significant increase of researches about teacher s professionalization. In that context, the investigations concerning teacher s knowledge represent an important contribution, as they aim to identify and to rescue the base of knowledge that sustains the teacher s profession. In particular, the reflections and propositions of Lee Shulman have been constitute a fundamental subsidy to the teacher s professionalization in the sense of harnessing the pedagogic knowledge to the content s knowledge, establishing the pedagogic knowledge of the content that characterizes and differentiates the teacher and the bachelor in a certain field of knowledge. Among the indispensable knowledge for the Chemistry teacher's professional practice, in this research we have pointed out the pertinence of the knowledge on the use of models in Chemistry classes in the middle and high school. Those knowledges regard the comprehension of students concerning the understanding and models elaborated in science and the models implemented in the Chemistry teaching, as well as the abilities to plan didactic situations that use models. In this research, we aimed to identify the contributions and barriers during the Chemistry teacher education, in UFRN, in relation to the construction of knowledge that subsidize training teachers in the elaboration of teaching activities that involve the use of models. The investigation was accomplished in UFRN, in the Course of Degree in Chemistry, along with 13 student teachers that studied the subject Practice of Chemistry Teaching. For this research, the following instruments were used: questionnaires with open and closed questions, elaboration of a plan of activities for the Chemistry teaching and an interview to answer the established study s questions. The data was analyzed in an established criteria, classified and tabled. The results showed that the student teachers representations regarding scientific knowledge contemplated, among other topics, the idea of a method for his/her construction. In some cases, the models role was emphasized in that construction, as well as the social dimension in the validation of that knowledge. The scientific models were highlighted by most of the student teachers, as a representation method to explain, understand and interpret the chemical phenomena. On the other hand, the didactic models stood out, in most of cases, as a method of aiding the Chemistry students of the Basic Education to understand the scientific models. The representations regarding those categories contemplated important aspects, although in a superficial way, reflecting the limitations of reflections during the formative process. In the elaboration of teaching activities that use models, difficulties were evidenced, in the process of plan construction, relative to the didactic structure and to the proposition of activities that contemplated models, although the student teachers have mobilized different elements regarding the pedagogic knowledge of the content. Such verifications evidence the urge for the teacher development programs to promote changes in the teacher education in order to propitiate, during this process, reflections, discussions and propositions of activities regarding categories highlighted in this research, contributing to the construction of initial elements regarding the pedagogic knowledge of the content that will be developed throughout teaching, therefore corroborating to the teacher s professionalization

The Digital Textbook: Methodological and Didactic Challenges for Primary School

The potentialities of ICT in education bring about changes in the teaching and learning methodologies, in the places where you learn and in the way you learn. This demands a reflection not only on the ways of learning, but also on the support resources, so that learning can take place and, of course, it is indispensable to understand the teachers’ answer to the digital challenges. Thus, the purpose of this analysis is to reflect about technological trends in an educational context and their underlying models by analyzing the role played by digital textbooks in Portugal in an innovating context. This way, we intend to contribute to an educational policy as we plan to relate the teachers’ training to the increasing development of the digital textbooks and we also intend to contribute to the understanding of a didactic resource which is closely related to the learning processes which resort to advanced technology.

Exact Search Directions for Optimization of Linear and Nonlinear Models Based on Generalized Orthonormal Functions

A novel technique for selecting the poles of orthonormal basis functions (OBF) in Volterra models of any order is presented. It is well-known that the usual large number of parameters required to describe the Volterra kernels can be significantly reduced by representing each kernel using an appropriate basis of orthonormal functions. Such a representation results in the so-called OBF Volterra model, which has a Wiener structure consisting of a linear dynamic generated by the orthonormal basis followed by a nonlinear static mapping given by the Volterra polynomial series. Aiming at optimizing the poles that fully parameterize the orthonormal bases, the exact gradients of the outputs of the orthonormal filters with respect to their poles are computed analytically by using a back-propagation-through-time technique. The expressions relative to the Kautz basis and to generalized orthonormal bases of functions (GOBF) are addressed; the ones related to the Laguerre basis follow straightforwardly as a particular case. The main innovation here is that the dynamic nature of the OBF filters is fully considered in the gradient computations. These gradients provide exact search directions for optimizing the poles of a given orthonormal basis. Such search directions can, in turn, be used as part of an optimization procedure to locate the minimum of a cost-function that takes into account the error of estimation of the system output. The Levenberg-Marquardt algorithm is adopted here as the optimization procedure. Unlike previous related work, the proposed approach relies solely on input-output data measured from the system to be modeled, i.e., no information about the Volterra kernels is required. Examples are presented to illustrate the application of this approach to the modeling of dynamic systems, including a real magnetic levitation system with nonlinear oscillatory behavior.

Tele-education environment and didactic iconography in sexual transmitted diseases

The field of advertising has developed techniques of mass communication and rapid transmission of information. Among these techniques are slogans and iconographies. This work used such tools for educational purposes and was divided into three modules. Module 1 evaluated the use of simplified textual communication (slogans) about the subject Sexually Transmitted Diseases. It was applied to third-year medical students, which had not taken the course on this theme. To evaluate the impact of the textual communication form (slogans), long phrases were elaborated in scientific language containing 15 topics. From these long phrases, compact phrases were developed using techniques of the advertising area for elaboration of slogans. Three forms of didactic material about that theme were developed. The first form consisted of long phrases in descriptive topics, using scientific language. The second was constituted exclusively of compact phrases in the form of slogans, and the third was composed of the combination of the two previous forms. Then, 10 multiple-choice questions were elaborated and applied in two phases. In the first phase, application occurred immediately after the reading of didactic texts; in the second phase, it happened 60 days after the reading. For statistical analysis, Snedcor's F test was used for analysis of variance, at 5% significance level. There was an increase in memorization by students who read the material containing the association between long phrases and slogans, which indicates that the latter, when used as an auxiliary model of learning, can bring significant benefits for education. Module 2 consisted of analyzing the elaboration of educational videos produced in graphic computing (called iconographies) for development of dynamic communication means. The theme Hair Cycle was utilized. Viability of high quantities of information in few minutes of animation could be demonstrated together with the advantage of presenting the process in a dynamic form without wasting scientific details. Module 3 presented the inclusion of slogans in educational videos produced in graphic computing about the Hair Cycle, showing a new tool for rapid and efficient transference of data. Slogans and iconographies, when utilized in educational material, can bring significant benefits for the student's learning.

Study of biosorption of rare earth metals (La, Nd, Eu, Gd) by Sargassum sp. biomass in batch systems: Physicochemical evaluation of kinetics and adsorption models

This work evaluated kinetic and adsorption physicochemical models for the biosorption process of lanthanum, neodymium, europium, and gadolinium by Sargassum sp. in batch systems. The results showed: (a) the pseudo-second order kinetic model was the best approximation for the experimental data with the metal adsorption initial velocity parameter in 0.042-0.055 mmol.g -1.min-1 (La < Nd < Gd < Eu); (b) the Langmuir adsorption model presented adequate correlation with maximum metal uptake at 0.60-0.70 mmol g-1 (Eu < La < Gd < Nd) and the metal-biomass affinity parameter showed distinct values (Gd < Nd < Eu < La: 183.1, 192.5, 678.3, and 837.3 L g-1, respectively); and (c) preliminarily, the kinetics and adsorption evaluation did not reveal a well-defined metal selectivity behavior for the RE biosorption in Sargassum sp., but they indicate a possible partition among RE studied. © (2009) Trans Tech Publications.

Outsourcing and acquisition models comparison related to IT supplier selection decision analysis

This paper presents a comparison of acquisition models related to decision analysis of IT supplier selection. The main standards are: Capability Maturity Model Integration for Acquisition (CMMI-ACQ), ISO / IEC 12207 Information Technology / Software Life Cycle Processes, IEEE 1062 Recommended Practice for Software Acquisition, the IT Infrastructure Library (ITIL) and the Project Management Body of Knowledge (PMBOK) guide. The objective of this paper is to compare the previous models to find the advantages and disadvantages of them for the future development of a decision model for IT supplier selection.

Modelling pre-clearing vegetation distribution using GIS-integrated statistical, ecological and data models: A case study from the wet tropics of Northeastern Australia

Traditional vegetation mapping methods use high cost, labour-intensive aerial photography interpretation. This approach can be subjective and is limited by factors such as the extent of remnant vegetation, and the differing scale and quality of aerial photography over time. An alternative approach is proposed which integrates a data model, a statistical model and an ecological model using sophisticated Geographic Information Systems (GIS) techniques and rule-based systems to support fine-scale vegetation community modelling. This approach is based on a more realistic representation of vegetation patterns with transitional gradients from one vegetation community to another. Arbitrary, though often unrealistic, sharp boundaries can be imposed on the model by the application of statistical methods. This GIS-integrated multivariate approach is applied to the problem of vegetation mapping in the complex vegetation communities of the Innisfail Lowlands in the Wet Tropics bioregion of Northeastern Australia. The paper presents the full cycle of this vegetation modelling approach including sampling sites, variable selection, model selection, model implementation, internal model assessment, model prediction assessments, models integration of discrete vegetation community models to generate a composite pre-clearing vegetation map, independent data set model validation and model prediction's scale assessments. An accurate pre-clearing vegetation map of the Innisfail Lowlands was generated (0.83r(2)) through GIS integration of 28 separate statistical models. This modelling approach has good potential for wider application, including provision of. vital information for conservation planning and management; a scientific basis for rehabilitation of disturbed and cleared areas; a viable method for the production of adequate vegetation maps for conservation and forestry planning of poorly-studied areas. (c) 2006 Elsevier B.V. All rights reserved.

Monitoring Infection Risk for Air and Soil Borne Fungal Plant Pathogens using Antibody and DNA Techniques and Mathematical Models describing Environmental Parameters

Economic losses resulting from disease development can be reduced by accurate and early detection of plant pathogens. Early detection can provide the grower with useful information on optimal crop rotation patterns, varietal selections, appropriate control measures, harvest date and post harvest handling. Classical methods for the isolation of pathogens are commonly used only after disease symptoms. This frequently results in a delay in application of control measures at potentially important periods in crop production. This paper describes the application of both antibody and DNA based systems to monitor infection risk of air and soil borne fungal pathogens and the use of this information with mathematical models describing risk of disease associated with environmental parameters.

Modelling solute transport in structured soils: Performance evaluation of the ADR and TRM models

The movement of chemicals through the soil to the groundwater or discharged to surface waters represents a degradation of these resources. In many cases, serious human and stock health implications are associated with this form of pollution. The chemicals of interest include nutrients, pesticides, salts, and industrial wastes. Recent studies have shown that current models and methods do not adequately describe the leaching of nutrients through soil, often underestimating the risk of groundwater contamination by surface-applied chemicals, and overestimating the concentration of resident solutes. This inaccuracy results primarily from ignoring soil structure and nonequilibrium between soil constituents, water, and solutes. A multiple sample percolation system (MSPS), consisting of 25 individual collection wells, was constructed to study the effects of localized soil heterogeneities on the transport of nutrients (NO3-, Cl-, PO43-) in the vadose zone of an agricultural soil predominantly dominated by clay. Very significant variations in drainage patterns across a small spatial scale were observed tone-way ANOVA, p < 0.001) indicating considerable heterogeneity in water flow patterns and nutrient leaching. Using data collected from the multiple sample percolation experiments, this paper compares the performance of two mathematical models for predicting solute transport, the advective-dispersion model with a reaction term (ADR), and a two-region preferential flow model (TRM) suitable for modelling nonequilibrium transport. These results have implications for modelling solute transport and predicting nutrient loading on a larger scale. (C) 2001 Elsevier Science Ltd. All rights reserved.

Dermaseptin 01 as antimicrobial peptide with rich biotechnological potential: study of peptide interaction with membranes containing Leishmania amazonensis lipid-rich extract and membrane models

This article addresses the interactions of the synthetic antimicrobial peptide dermaseptin 01 (GLWSTIKQKGKEAAIAAA-KAAGQAALGAL-NH(2), DS 01) with phospholipid (PL) monolayers comprising (i) a lipid-rich extract of Leishmania amazonensis (LRE-La), (ii) zwitterionic PL (dipalmitoylphosphatidylcholine, DPPC), and (iii) negatively charged PL (dipalmitoylphosphatidylglycerol, DPPG). The degree of interaction of DS 01 with the different biomembrane models was quantified from equilibrium and dynamic liquid-air interface parameters. At low peptide concentrations, interactions between DS 01 and zwitterionic PL, as well as with the LRE-La monolayers were very weak, whereas with negatively charged PLs the interactions were stronger. For peptide concentrations above 1 mu g/ml, a considerable expansion of negatively charged monolayers occurred. In the case of DPPC, it was possible to return to the original lipid area in the condensed phase, suggesting that the peptide was expelled from the monolayer. However, in the case of DPPG, the average area per lipid molecule in the presence of DS 01 was higher than pure PLs even at high surface pressures, suggesting that at least part of DS 01 remained incorporated in the monolayer. For the LRE-La monolayers, DS 01 also remained in the monolayer. This is the first report on the antiparasitic activity of AMPs using Langmuir monolayers of a natural lipid extract from L. amazonensis. Copyright (C) 2011 European Peptide Society and John Wiley & Sons, Ltd.

Discrete and continuous models for dry masonry columns

The dynamic response of dry masonry columns can be approximated with finite-difference equations. Continuum models follow by replacing the difference quotients of the discrete model by corresponding differential expressions. The mathematically simplest of these models is a one-dimensional Cosserat theory. Within the presented homogenization context, the Cosserat theory is obtained by making ad hoc assumptions regarding the relative importance of certain terms in the differential expansions. The quality of approximation of the various theories is tested by comparison of the dispersion relations for bending waves with the dispersion relation of the discrete theory. All theories coincide with differences of less than 1% for wave-length-block-height (L/h) ratios bigger than 2 pi. The theory based on systematic differential approximation remains accurate up to L/h = 3 and then diverges rapidly. The Cosserat model becomes increasingly inaccurate for L/h < 2 pi. However, in contrast to the systematic approximation, the wave speed remains finite. In conclusion, considering its relative simplicity, the Cosserat model appears to be the natural starting point for the development of continuum models for blocky structures.

Virtual plants - integrating architectural and physiological models

Recent advances in computer technology have made it possible to create virtual plants by simulating the details of structural development of individual plants. Software has been developed that processes plant models expressed in a special purpose mini-language based on the Lindenmayer system formalism. These models can be extended from their architectural basis to capture plant physiology by integrating them with crop models, which estimate biomass production as a consequence of environmental inputs. Through this process, virtual plants will gain the ability to react to broad environmental conditions, while crop models will gain a visualisation component. This integration requires the resolution of the fundamentally different time scales underlying the approaches. Architectural models are usually based on physiological time; each time step encompasses the same amount of development in the plant, without regard to the passage of real time. In contrast, physiological models are based in real time; the amount of development in a time step is dependent on environmental conditions during the period. This paper provides a background on the plant modelling language, then describes how widely-used concepts of thermal time can be implemented to resolve these time scale differences. The process is illustrated using a case study. (C) 1997 Elsevier Science Ltd.