Expressiveness and definability in circumscription

We investigate expressiveness and definability issues with respect to minimal models, particularly in the scope of Circumscription. First, we give a proof of the failure of the Löwenheim-Skolem Theorem for Circumscription. Then we show that, if the class of P; Z-minimal models of a first-order sentence is Δ-elementary, then it is elementary. That is, whenever the circumscription of a first-order sentence is equivalent to a first-order theory, then it is equivalent to a finitely axiomatizable one. This means that classes of models of circumscribed theories are either elementary or not Δ-elementary. Finally, using the previous result, we prove that, whenever a relation Pi is defined in the class of P; Z-minimal models of a first-order sentence Φ and whenever such class of P; Z-minimal models is Δ-elementary, then there is an explicit definition ψ for Pi such that the class of P; Z-minimal models of Φ is the class of models of Φ ∧ ψ. In order words, the circumscription of P in Φ with Z varied can be replaced by Φ plus this explicit definition ψ for Pi.

Marketing in the pre-development process of agricultural machines: a reference model

The theme of the research is the development of the domain of marketing knowledge in the design of agricultural machinery. It is developed throughout the design of agricultural machinery in order to identify the corporate and customers needs and to develop strategies to satisfy these needs. The central problem of the research questions which marketing tools to apply on pre-development process of farm machinery, in order to increase the market value of the products and of the company and, consequently, generate competitive advantage to the manufacturers of agricultural machinery. As methodology, it was developed bibliographical research and multicase study of the development process of agricultural machinery developed by small, medium and large companies and the academy. As a result, a marketing reference model was elaborated for the pre-development stage of agricultural machinery, which outlines the activities, tasks, mechanisms and controls that can be used in strategic planning and in products planning of agricultural machinery manufacturers, contributing to explain the explicit knowledge in the marketing field.

Geometric nonlinear dynamic analysis of plates and shells using eight-node hexahedral finite elements with reduced integration

This work presents a geometric nonlinear dynamic analysis of plates and shells using eight-node hexahedral isoparametric elements. The main features of the present formulation are: (a) the element matrices are obtained using reduced integrations with hourglass control; (b) an explicit Taylor-Galerkin scheme is used to carry out the dynamic analysis, solving the corresponding equations of motion in terms of velocity components; (c) the Truesdell stress rate tensor is used; (d) the vector processor facilities existing in modern supercomputers were used. The results obtained are comparable with previous solutions in terms of accuracy and computational performance.

A new approach to evaluate imperfection sensitivity in asymmetric bifurcation buckling analysis

A direct procedure for the evaluation of imperfection sensitivity in bifurcation problems is presented. The problems arise in the context of the general theory of elastic stability for discrete structural systems, in which the energy criterion of stability of structures and the total potential energy formulation are employed. In cases of bifurcation buckling the sensitivity of the critical load with respect to an imperfection parameter e is singular at the state given by epsilon =0, so that, a regular perturbation expansion of the solution is not possible. In this work we describe a direct procedure to obtain the relations between the critical loads, the generalized coordinates at the critical state, the eigenvector, and the amplitude of the imperfection, using singular perturbation analysis. The expansions are assumed in terms of arbitrary powers of the imperfection parameter, so that both exponents and coefficients of the expansion are unknown. The solution of the series exponents is obtained by searching the least degenerate solution. The formulation is here applied to asymmetric bifurcations, for which explicit expressions of the coefficients are obtained. The use of the method is illustrated by a simple example, which allows consideration of the main features of the formulation.

Solution of aerospace problems using structured and unstructured strategies

Products developed at industries, institutes and research centers are expected to have high level of quality and performance, having a minimum waste, which require efficient and robust tools to numerically simulate stringent project conditions with great reliability. In this context, Computational Fluid Dynamics (CFD) plays an important role and the present work shows two numerical algorithms that are used in the CFD community to solve the Euler and Navier-Stokes equations applied to typical aerospace and aeronautical problems. Particularly, unstructured discretization of the spatial domain has gained special attention by the international community due to its ease in discretizing complex spatial domains. This work has the main objective of illustrating some advantages and disadvantages of numerical algorithms using structured and unstructured spatial discretization of the flow governing equations. Numerical methods include a finite volume formulation and the Euler and Navier-Stokes equations are applied to solve a transonic nozzle problem, a low supersonic airfoil problem and a hypersonic inlet problem. In a structured context, these problems are solved using MacCormack’s implicit algorithm with Steger and Warming’s flux vector splitting technique, while, in an unstructured context, Jameson and Mavriplis’ explicit algorithm is used. Convergence acceleration is obtained using a spatially variable time stepping procedure.

Mountain biodiversity in Brazil

The high species richness and diversity found in tropical montane habitats are often related to: 1) an effect of climatic and geological history on biotic evolution; 2) the various environmental impacts on species adaptation mechanisms; and 3) the continuous dispersal of fauna and flora in time. However, little is known about how these factors shaped species richness in Brazilian mountains. Official documents on biodiversity in Brazil make no explicit reference to mountains, even though there is a mountain work programme of the Convention on Biological Diversity, which Brazil is a signatory of. This paper discusses the importance of mountain ecosystems in Brazil to show the urgent need to include mountain biodiversity in the national agenda of biodiversity research and conservation.

The brain decade in debate: I. Neurobiology of learning and memory

This article is a transcription of an electronic symposium in which some active researchers were invited by the Brazilian Society for Neuroscience and Behavior (SBNeC) to discuss the last decade's advances in neurobiology of learning and memory. The way different parts of the brain are recruited during the storage of different kinds of memory (e.g., short-term vs long-term memory, declarative vs procedural memory) and even the property of these divisions were discussed. It was pointed out that the brain does not really store memories, but stores traces of information that are later used to create memories, not always expressing a completely veridical picture of the past experienced reality. To perform this process different parts of the brain act as important nodes of the neural network that encode, store and retrieve the information that will be used to create memories. Some of the brain regions are recognizably active during the activation of short-term working memory (e.g., prefrontal cortex), or the storage of information retrieved as long-term explicit memories (e.g., hippocampus and related cortical areas) or the modulation of the storage of memories related to emotional events (e.g., amygdala). This does not mean that there is a separate neural structure completely supporting the storage of each kind of memory but means that these memories critically depend on the functioning of these neural structures. The current view is that there is no sense in talking about hippocampus-based or amygdala-based memory since this implies that there is a one-to-one correspondence. The present question to be solved is how systems interact in memory. The pertinence of attributing a critical role to cellular processes like synaptic tagging and protein kinase A activation to explain the memory storage processes at the cellular level was also discussed.

The modulation of simple reaction time by the spatial probability of a visual stimulus

Simple reaction time (SRT) in response to visual stimuli can be influenced by many stimulus features. The speed and accuracy with which observers respond to a visual stimulus may be improved by prior knowledge about the stimulus location, which can be obtained by manipulating the spatial probability of the stimulus. However, when higher spatial probability is achieved by holding constant the stimulus location throughout successive trials, the resulting improvement in performance can also be due to local sensory facilitation caused by the recurrent spatial location of a visual target (position priming). The main objective of the present investigation was to quantitatively evaluate the modulation of SRT by the spatial probability structure of a visual stimulus. In two experiments the volunteers had to respond as quickly as possible to the visual target presented on a computer screen by pressing an optic key with the index finger of the dominant hand. Experiment 1 (N = 14) investigated how SRT changed as a function of both the different levels of spatial probability and the subject's explicit knowledge about the precise probability structure of visual stimulation. We found a gradual decrease in SRT with increasing spatial probability of a visual target regardless of the observer's previous knowledge concerning the spatial probability of the stimulus. Error rates, below 2%, were independent of the spatial probability structure of the visual stimulus, suggesting the absence of a speed-accuracy trade-off. Experiment 2 (N = 12) examined whether changes in SRT in response to a spatially recurrent visual target might be accounted for simply by sensory and temporally local facilitation. The findings indicated that the decrease in SRT brought about by a spatially recurrent target was associated with its spatial predictability, and could not be accounted for solely in terms of sensory priming.

Reliability and validity of a Portuguese version of the Young Mania Rating Scale

The reliability and validity of a Portuguese version of the Young Mania Rating Scale were evaluated. The original scale was translated into and adapted to Portuguese by the authors. Definitions of clinical manifestations, a semi-structured anchored interview and more explicit rating criteria were added to the scale. Fifty-five adult subjects, aged 18 to 60 years, with a diagnosis of Current Manic Episode according to DSM-III-R criteria were assessed using the Young Mania Rating Scale as well as the Brief Psychiatric Rating Scale in two sessions held at intervals from 7 to 10 days. Good reliability ratings were obtained, with intra-class correlation coefficient of 0.97 for total scores, and levels of agreement above 0.80 (P < 0.001) for all individual items. Internal consistency analysis resulted in an alpha = 0.67 for the scale as a whole, and an alpha = 0.72 for each standardized item (P < 0.001). For the concurrent validity, a correlation of 0.78 was obtained by the Pearson coefficient between the total scores of the Young Mania Rating Scale and Brief Psychiatric Rating Scale. The results are similar to those reported for the English version, indicating that the Portuguese version of the scale constitutes a reliable and valid instrument for the assessment of manic patients.

An MD-PhD program in Brazil: students’ concepts of science and of common sense

In 1995, a pioneering MD-PhD program was initiated in Brazil for the training of medical scientists in experimental sciences at the Federal University of Rio de Janeiro. The program’s aim was achieved with respect to publication of theses in the form of papers with international visibility and also in terms of fostering the scientific careers of the graduates. The expansion of this type of program is one of the strategies for improving the preparation of biomedical researchers in Brazil. A noteworthy absence of interest in carrying out clinical research limits the ability of young Brazilian physicians to solve biomedical problems. To understand the students’ views of science, we used qualitative and quantitative triangulation methods, as well as participant observation to evaluate the students’ concepts of science and common sense. Subjective aspects were clearly less evident in their concepts of science. There was a strong concern about "methodology", "truth" and "usefulness". "Intuition", "creativity" and "curiosity" were the least mentioned thematic categories. Students recognized the value of intuition when it appeared as an explicit option but they did not refer to it spontaneously. Common sense was associated with "consensus", "opinion" and ideas that "require scientific validation". Such observations indicate that MD-PhD students share with their senior academic colleagues the same reluctance to consider common sense as a valid adjunct for the solution of scientific problems. Overcoming this difficulty may be an important step toward stimulating the interest of physicians in pursuing experimental research.

Políticas Sociais: focalização ou universalização?

Public debate on social policies in Brazil has focused on the choice between targeted and universal programs. The article argues that the choice is unclear and misleading unless a previous decision is taken concerning principles of social justice. After distinguishing three different connotations of targeting - as residualism, conditionality or retification - and noting that universal programs may be compatible with minimalist social policy, the article goes on to make explicit a number of neglected options.

Capital intangível e direitos de propriedade intelectual: uma análise institucionalista

This paper deals with the main evolutions that explain the emergence of new institutional arrangements that characterize the post-fordism. (i) Hence, I will show that the property rights modifications bring forth new forms of competition;(ii) Also, I will make explicit the concrete expressions of this new competition, as well as how it translates itself in a sub-optimum allocation in the framework of the market game; (iii) I will study the modifications of externalities nature produced by technical progress; (iv) Finally, I will analyze the macroeconomic implications in regard to growth mechanisms and to capital nature.

Diferentes padrões de políticas salariais nos estados brasileiros: uma análise a partir do diferencial de salários público-privado

Public servant wages represent a significant part of Brazilian state governments' current expenses. Based on the literature, this paper has tried to identify which states practice efficient, compensatory or appropriation wage politics through the estimation of public-private wage differentials. The differential of salaries was calculated between 1995 and 2004 following the Oaxaca's technique. The results show that the wage policy of an important number of states has had efficiency and a numerous part of the North and the Northeast states have developed compensatory politics. The Federal District and Roraima practiced a wage policy characterized by explicit appropriation.

Justiça e desenvolvimento no pensamento de Amartya Sen

This article aims to present an overview of Amartya Sen's thought, relating to his writings on political philosophy and his contributions to the field of development economics. This paper shows how justice and development are highly related in Sen's approach based on the concept of capability. Along with this paper, we will present some debates between Sen and John Rawls, beside other critics. This is done to explain the complex theoretical system elaborated by him. In concluding, the paper shows that the objective of Sen is to find a satisfactory concept of development that is explicit in its ethical presumptions.

Os fluxos de IDE no Brasil nos anos 1990: uma revisão de literatura à luz das transformações em curso

The flows of foreign investments in Brazil starting from the 1990s have called attention due to the magnitude of the invested value, the prevalence of properties acquisitions as a preferential way of carrying out these investments, and for the primacy of the operations involving rivals companies. This article searches for an explanation for the cycle of foreign direct investment flows, which is happening in Brazil. Arguments were reconsidered on the existence of sole assets and the advantages of property and control as a basis for carrying out overseas investments, and to explicit their link with the M&As.