Varenius e o conhecimento matemático do século XVII

Neste artigo, discutimos o contexto do desenvolvimento da Geografia que, no século XVII, liberou-se do seu papel nas diferentes fés cristãs, bem como a importância da cisão dos Protestantes, em Luteranos e Calvinistas, para o processo de secularização, e o conseguinte estabelecimento da Geografia como ciência moderna. Analisamos a contribuição fundamental do luterano Bernhard Varen, cuja obra Geografia Geral apresenta o paradigma dessa nova ciência. Naquela época, a Geografia era considerada um ramo da matemática, e esta obra nos dá indícios sobre notações e conceitos matemáticos utilizados naquele século. Analisamos, particularmente, o uso da notação decimal de números não inteiros e algumas aplicações de conceitos trigonométricos, comparando a edição original com as principais reedições desta obra.

Cafeicultura científica globalizada e as montanhas capixabas: a produção de caféarábica nas regiões do Caparaó e Serrana do Espírito Santo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A produção dos signos numa estrutura social antagônica

A partir de objeções às proposições de Mikhail BAKHTIN (ou V.N. VOLOCHINOV) sobre a produção da linguagem e do discurso literário no interior das relações sociais de produção, sugere-se a aplicação da semiótica peirceana, devidamente criticada para a análise da produção dos signos no nível da representação da consciência. Pretende-se com isto considerar o signo em toda a sua extensão, e não reduzido ao mero domínio do simbólico, e tornar mais claro o lugar e o papel das diversas formas ideológicas no interior da praxis.

BOUSSINESQ-TYPE SYSTEM OF EQUATIONS IN THE BENARD-MARANGONI SYSTEM

A system of coupled evolution equations for the bulk velocity and the surface displacement is found to govern the long-wavelength perturbations in a Benard-Marangoni system. This system of equations, involving nonlinearity, dispersion, and dissipation, is a generalization of the usual Boussinesq system.

Podolsky's higher-order electromagnetism from first principles

Podolsky's higher-order field equations are obtained by generalizing the laws of Podolsky's electrostatics, which follow from Coulomb's generalized law and superposition, to be consistent with special relativity. In addition, it is necessary to take into account the independence of the observed charge of a particle on its speed. It is also shown that the gauge-independent term concerning the Feynman propagator for Podolsky's generalized electrodynamics has a good ultraviolet behaviour at the expense of a negative metric massive ghost which, contrary to what is currently assumed in the literature, is non-tachyonic. A brief discussion on Podolsky's characteristic length is presented as well.

DIRAC CONFINEMENT BY A VARIATIONAL APPROACH

An analytical approximate method for the Dirac equation with confining power law scalar plus vector potentials, applicable to the problem of the relativistic quark confinement, is presented. The method consists in an improved version of a saddle-point variational approach and it is applied to the fundamental state of massless single quarks for some especial cases of physical interest. Our treatment emphasizes aspects such as the quantum-mechanical relativistic Virial theorem, the saddle-point character of the critical point of the expectation value of the total energy, as well as the Klein paradox and the behaviour of the saddle-point variational energies and wave functions.

Nonperturbative approach to potentials in impenetrable boxes based on quasi-exact solvability

In this work we develop an approach to obtain analytical expressions for potentials in an impenetrable box. In this kind of system the expression has the advantage of being valid for arbitrary values of the box length, and respect the correct quantum limits. The similarity of this kind of problem with the quasi exactly solvable potentials is explored in order to accomplish our goals. Problems related to the break of symmetries and simultaneous eigenfunctions of commuting operators are discussed.

Causal propagators for algebraic gauges

Applying the principle of analytic extension for generalized functions we derive causal propagators for algebraic non-covariant gauges. The so-generated manifestly causal gluon propagator in the light-cone gauge is used to evaluate two one-loop Feynman integrals which appear in the computation of the three-gluon vertex correction. The result is in agreement with that obtained through the usual prescriptions.

Hamilton-Jacobi formulation for singular systems with second-order Lagrangians

Recently, the Hamilton-Jacobi formulation for first-order constrained systems has been developed. In such formalism the equations of motion are written as total differential equations in many variables. We generalize the Hamilton-Jacobi formulation for singular systems with second-order Lagrangians and apply this new formulation to Podolsky electrodynamics, comparing with the results obtained through Dirac's method.

Comparison of Lagrangian Bounds for One Class of Generalized Assignment Problems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Lazer, aventura e risco: reflexões sobre atividades realizadas na natureza

This paper reflects on the conceptions of adventure and risk, revealed in activities in nature. The presented speeches are contained in a research, whose boarding works with a universe of reasons, aspirations, values, beliefs and attitudes, corresponding to a deeper space of the processes, relations and phenomena. It was possible to perceive that the adventure activities in nature are carrying of innumerable meanings, related with new discoveries, new challenges, search for the stranger, uncertainty, cooperation, friendship, among others. Such activities understand diverse forms of experimentation, pointing besides to physical risk, the symbolic and imaginary risk.

Desenvolvimento da quantificacao em geografia

Considering the textbooks, papers and articles published during the last decades, this paper deals with the development of the quantitative analysis in Geography. The comments are grouped into the following thematic questions: contributions aiming to introduce concepts and techniques in the geographical issues, focusing statistical and mathematical background and specific techniques about spatial and temporal distributions; contributions evaluating the potentialities of the quantification; contributions showing the character and applicability of the quantificative techniques, and the state of the use of these techniques in Brazilian literature and teaching. -English summary

Connection space approach to ambiguities of gauge theories

Two distinct gauge potentials can have the same field strength, in which case they are said to be copies of each other. The consequences of this ambiguity for the general affine space A of gauge potentials are examined. Any two potentials are connected by a straight line in A, but a straight line going through two copies either contains no other copy or is entirely formed by copies. Copyright © 2005 Hindawi Publishing Corporation.