NIELSEN COINCIDENCE THEORY OF FIBRE-PRESERVING MAPS AND DOLD`S FIXED POINT INDEX

Let M -> B, N -> B be fibrations and f(1), f(2): M -> N be a pair of fibre-preserving maps. Using normal bordism techniques we define an invariant which is an obstruction to deforming the pair f(1), f(2) over B to a coincidence free pair of maps. In the special case where the two fibrations axe the same and one of the maps is the identity, a weak version of our omega-invariant turns out to equal Dold`s fixed point index of fibre-preserving maps. The concepts of Reidemeister classes and Nielsen coincidence classes over B are developed. As an illustration we compute e.g. the minimal number of coincidence components for all homotopy classes of maps between S(1)-bundles over S(1) as well as their Nielsen and Reidemeister numbers.

Towards an epistemological theory of historical consciousness

This paper presents a theoretical analysis of the concept of historical consciousness. It argues that a focus on the epistemological problems of the concept can be a way of constructing a theory of the concept that both incorporates the diverse perspectives that exist in research about the concept and specifies how a historical consciousness can be developed in an individual.

Vector Theory of Spontaneous Lorentz Violation

Classical electromagnetism predicts two massless propagating modes, which are known as the two polarizations of the photon. On the other hand, if the Lorentz symmetry of classical electromagnetism is spontaneously broken, the new theory will still have two massless Nambu-Goldstone modes resembling the photon. If the Lorentz symmetry is broken by a bumblebee potential that allows for excitations out of the minimum, then massive modes arise. Furthermore, in curved spacetime, such massive modes will be created through a process other than the usual Higgs mechanism because of the dependence of the bumblebee potential on both the vector field and the metric tensor. Also, it is found that these massive modes do not propagate due to the extra constraints.

Overdetermination in a marxian theory of money

O presente artigo focaliza a genérica e abstrata análise monetária desenvolvida por Marx no inicio do Capital. Mais precisamente, pretende-se avaliar em que medida, se alguma, alguns aspectos da análise de Marx sobre o papel bastante contraditório desempenhado pela moeda no processo de circulação simples de mercadorias suportam uma interpretação sobre-determinista do método dialético por ele empregado. Baseando-se no conceito de sobre-determinação introduzido na literature Marxiana principalmente por Louis Althusser, o artigo conclui que o nexo real-monetário prevalecente na circulação simples de mercadorias pode ser concebida como um nexo sobre-determinado, ou seja, um nexo caracterizado por incorporar um regime de constitutividade.

“Conflito de interesses” nas sociedades anônimas: análise do art. 156 e sua eficácia jurídica

O presente estudo objetiva analisar, sob o ponto de vista doutrinário e jurisprudencial, a redação da disposição legal do art. 156, contida na Lei 6.404, de 1976, “Lei das Sociedades Anônimas, acerca do conflito de interesses de administrador que, por conter um conceito jurídico indeterminado ainda não aclarado por lei nem pela Comissão de Valores Mobiliários, é objeto de decisões divergentes quanto a sua aplicação fática, gerando impactos em sua eficácia jurídica. Inicialmente serão explicitadas as teorias doutrinárias que referendam o tema e cuja aplicação encontram terreno na jurisprudência. Em seguida, será contextualizado historicamente o surgimento do conflito de interesses de administrador no direito pátrio. Após esta exposição, tratar-se-á do conceito de eficácia jurídica a ser utilizado nesta análise, para que se possa alcançar sua verificação no art. 156.

A theory of weekly specials

Multiproduct retailers facing similar costs and serving the same public commonly announce different weekly specials. These promotional prices also seem to evolve randomly over the weeks. Here, weekly specials are viewed as the strategic outcome of an oligopolistic price competition among multiproduct retail stores facing nonconvex costs. Existence of an equilibrium in mixed strategies is proven. ldentical stores serving the same public will never charge the same price vector with probability one (cross-store price dispersion). Mixed strategies can generate random price dispersion over time in the repeated version of the mode!.

Toward a theory of international currency : a step further

We generalize the two-country, two-currency model of Matsuyama, Kiyotaki and Matsui to resolve two "shortcomings" in their approach. First, we endogenize prices and excb.ange rates. Second, we introduce monetary policy. We then use the model to address the following new questions: How does the fact that a currency circulates intemationally affect its purcb.asing power? Where does an intemational currency purcb.ase more? What are the effects on seignorage and welfare when a currency becomes intemational? How is policy affected by concems of currency substitution? How are national monetary policies connected, and what is the scope for international cooperation?

O voto em conflito de interesses no âmbito do direito societário

O presente trabalho tem como objetivo analisar o tratamento que vem sendo conferido pelo Direito Societário brasileiro ao voto proferido em conflito de interesses nas assembleias de acionistas das Sociedades Anônimas. Nesse sentido, foi analisado o tratamento dado pela legislação vigente e a interpretação tanto da jurisprudência como da doutrina relacionada. Duas correntes interpretativas predominam, quais sejam a do conflito formal e substancial de interesses. Elas propõem consequências práticas distintas: a primeira prevê a vedação ex ante do exercício de voto e a segunda o controle ex post do voto. Observa-se predominância na doutrina da interpretação materialista do conflito de interesses, e na jurisprudência da Comissão de Valores Mobiliários por interpretações formalistas. Diante desse panorama, será feito uma análise crítica dos principais argumentos trazidos pelas duas correntes que se destacam na doutrina e nas decisões da Comissão de Valores Mobiliários.

A Theory of voter experimentation in repeated elections

Nesse artigo, eu desenvolvo e analiso um modelo de dois perí odos em que dois polí ticos competem pela preferência de um eleitor representativo, que sabe quão benevolente é um dos polí ticos mas é imperfeitamente informado sobre quão benevolente é o segundo polí tico. O polí tico conhecido é interpretado como um incumbente de longo prazo, ao passo que o polí tico desconhecido é interpretado como um desa fiante menos conhecido. É estabelecido que o mecanismo de provisão de incentivos inerente às elei cões - que surge através da possibilidade de não reeleger um incumbente - e considerações acerca de aquisi cão de informa cão por parte do eleitor se combinam de modo a determinar que em qualquer equilí brio desse jogo o eleitor escolhe o polí tico desconhecido no per íodo inicial do modelo - uma a cão à qual me refi ro como experimenta cão -, fornecendo assim uma racionaliza cão para a não reelei cão de incumbentes longevos. Especifi camente, eu mostro que a decisão do eleitor quanto a quem eleger no per odo inicial se reduz à compara cão entre os benefí cios informacionais de escolher o polí tico desconhecido e as perdas econômicas de fazê-lo. Os primeiros, que capturam as considera cões relacionadas à aquisi cão de informa cão, são mostrados serem sempre positivos, ao passo que as últimas, que capturam o incentivo à boa performance, são sempre não-negativas, implicando que é sempre ótimo para o eleitor escolher o polí tico desconhecido no per íodo inicial.

Theory of small aspect ratio waves in deep water

In the limit of small values of the aspect ratio parameter (or wave steepness) which measures the amplitude of a surface wave in units of its wave-length, a model equation is derived from the Euler system in infinite depth (deep water) without potential flow assumption. The resulting equation is shown to sustain periodic waves which on the one side tend to the proper linear limit at small amplitudes, on the other side possess a threshold amplitude where wave crest peaking is achieved. An explicit expression of the crest angle at wave breaking is found in terms of the wave velocity. By numerical simulations, stable soliton-like solutions (experiencing elastic interactions) propagate in a given velocities range on the edge of which they tend to the peakon solution. (c) 2005 Elsevier B.V. All rights reserved.

Higher-derivative theory of (2+1)-dimensional gravity

Higher-derivative gravity in 2 + 1 dimensions is considered. The general solution of the linearized field equations in a three-dimensional version of the Teyssandier gauge is obtained, and from that the solution for a static pointlike source is found. The deflection of light rays is also analysed. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Conformal field theory of AdS background with Ramond-Ramond flux

We review a formalism of superstring quantization with manifest six-dimensional spacetime supersymmetry, and apply it to AdS(3) x S-3 backgrounds with Ramond-Ramond flux. The resulting description is a conformal field theory based on a sigma model whose target space is a certain supergroup SU' (2\2).

Theory of optical dispersive shock waves in photorefractive media

The theory of optical dispersive shocks generated in the propagation of light beams through photorefractive media is developed. A full one-dimensional analytical theory based on the Whitham modulation approach is given for the simplest case of a sharp steplike initial discontinuity in a beam with one-dimensional striplike geometry. This approach is confirmed by numerical simulations, which are extended also to beams with cylindrical symmetry. The theory explains recent experiments where such dispersive shock waves have been observed.

THEORY OF ELECTRICAL CHARACTERISTICS OF A SCHOTTKY-BARRIER HAVING EXPONENTIALLY DISTRIBUTED IMPURITY STATES AND METAL-INSULATOR METAL STRUCTURES

The metal-insulator or metal-amorphous semiconductor blocking contact is still not well understood. Here, we discuss the steady state characteristics of a non-intimate metal-insulator Schottky barrier. We consider an exponential distribution (in energy) of impurity states in addition to impurity states at a single energy level within the depletion region. We present analytical expressions for the electrical potential, field, thickness of depletion region, capacitance, and charge accumulated in the depletion region. We also discuss ln I versus V(ap) data. Finally, we compare the characteristics in three cases: (i) impurity states at only a single energy level; (ii) uniform energy distribution of impurity states; and (iii) exponential energy distribution of impurity states.In general, the electrical characteristics of Schottky barriers and metal-insulator-metal structures with Schottky barriers depend strongly on the energy distribution of impurity states.

THEORY OF NON-STEADY-STATE ELECTRICAL CHARACTERISTICS OF METAL-INSULATOR-METAL STRUCTURES WITH SCHOTTKY BARRIERS AND UNIFORMLY DISTRIBUTED INTERFACE IMPURITY STATES

The metal-insulator (or amorphous semiconductor) blocking contact is still not well understood. In the present paper, we discuss the non steady state characteristics of Metal-lnsulator-Metal Structure with non-intimate blocking contacts (i.e. Metal-Oxide-Insulator-Metal Structure). We consider a uniform distribution (in energy) of impurity states in addition to impurity states at a single energy level within the depletion region. We discuss thermal as well as isothermal characteristics and present expressions for the temperature of maximum current (T-m) and a method to calculate the density of uniformly distributed impurity states. The variation of mobility with electrical field has also been considered. Finally we plot the theoretical curves under different conditions. The present results are closing into available experimental results.