Teleparallel equivalent of the Kaluza-Klein theory

Relying upon the equivalence between a gauge theory for the translation group and general relativity, a teleparallel version of the original Kaluza-Klein theory is developed. In this model, only the internal space (fiber) turns out to be five dimensional, spacetime being kept always four dimensional. A five-dimensional translational gauge theory is obtained which unifies, in the sense of Kaluza-Klein theories, gravitational and electromagnetic interactions. ©2000 The American Physical Society.

Duality in a fermionlike formulation for the electromagnetic field

We employ the Dirac-like equation for the gauge field proposed by Majorana to obtain an action that is symmetric under duality transformation. We also use the equivalence between duality and chiral symmetry in this fermionlike formulation to show how the Maxwell action can be seen as a mass term. ©2000 The American Physical Society.

Confinement and soliton solutions in the SL(3) Toda model coupled to matter fields

We consider an integrable conformally invariant two-dimensional model associated to the affine Kac-Moody algebra sl3(ℂ). It possesses four scalar fields and six Dirac spinors. The theory does not possesses a local Lagrangian since the spinor equations of motion present interaction terms which are bilinear in the spinors. There exists a submodel presenting an equivalence between a U(1) vector current and a topological current, which leads to a confinement of the spinors inside the solitons. We calculate the one-soliton and two-soliton solutions using a procedure which is a hybrid of the dressing and Hirota methods. The soliton masses and time delays due to the soliton interactions are also calculated. We give a computer program to calculate the soliton solutions. © 2002 Published by Elsevier Science B.V.

Higher grading conformal affine Toda theory and (generalized) sine-Gordon/massive Thirring duality

Some properties of the higher grading integrable generalizations of the conformal affine Toda systems are studied. The fields associated to the non-zero grade generators are Dirac spinors. The effective action is written in terms of the Wess-Zumino-Novikov-Witten (WZNW) action associated to an affine Lie algebra, and an off-critical theory is obtained as the result of the spontaneous breakdown of the conformal symmetry. Moreover, the off-critical theory presents a remarkable equivalence between the Noether and topological currents of the model. Related to the off-critical model we define a real and local lagrangian provided some reality conditions are imposed on the fields of the model. This real action model is expected to describe the soliton sector of the original model, and turns out to be the master action from which we uncover the weak-strong phases described by (generalized) massive Thirring and sine-Gordon type models, respectively. The case of any (untwisted) affine Lie algebra furnished with the principal gradation is studied in some detail. The example of s^l(n) (n = 2, 3) is presented explicitly. © SISSA/ISAS 2003.

Experimental aspects of partially premixed pulsating combustion

The pulsating combustion process has won interest in current research due to indications that its application in energy generation can offer several advantages, such as: fuel economy, reduced pollutants formation, increased rate of convective heat transfer and reduced investment, when compared with conventional techniques. An experimental study has been conducted with the objective of investigating the effects of combustion driven acoustic oscillations in the emission rates of combustion gases, especially carbon monoxide and nitrogen oxides. The experiments were conducted in a water-jacketed 1-m long by 25-cm internal diameter stainless steel vertical tube. The combustor operated with liquefied petroleum gas (LPG) in both oscillatory and non oscillatory conditions, under the same input conditions. Part of the reactant mixture was excited acoustically, before the burner exit, by a speaker positioned strategically. The burner was aligned with the chamber longitudinal axis and positioned at its bottom. The experiments were conducted for 0.16 g/s of LPG burning in stoichiometric equivalence ratio. The main conclusions were: a) the pulsating combustion process produces more uniform fuel/air profile than the non pulsating process, b) close to stoichiometric equivalence ratio the pulsating combustion process generates higher rates of NO x; c) the frequency has a strong influence in NO x emission, but the pressure amplitude has a weak influence; d) the presence of the acoustic field may change drastically the combustion gas emissions in diffusion flames, but in pre-mixed flames the influence is not as strong.

Gravity and the quantum: Are they reconcilable?

General relativity and quantum mechanics are not consistent with each other. This conflict stems from the very fundamental principles on which these theories are grounded. General relativity, on one hand, is based on the equivalence principle, whose strong version establishes the local equivalence between gravitation and inertia. Quantum mechanics, on the other hand, is fundamentally based on the uncertainty principle, which is essentially nonlocal. This difference precludes the existence of a quantum version of the strong equivalence principle, and consequently of a quantum version of general relativity. Furthermore, there are compelling experimental evidences that a quantum object in the presence of a gravitational field violates the weak equivalence principle. Now it so happens that, in addition to general relativity, gravitation has an alternative, though equivalent, description, given by teleparallel gravity, a gauge theory for the translation group. In this theory torsion, instead of curvature, is assumed to represent the gravitational field. These two descriptions lead to the same classical results, but are conceptually different. In general relativity, curvature geometrizes the interaction while torsion, in teleparallel gravity, acts as a force, similar to the Lorentz force of electrodynamics. Because of this peculiar property, teleparallel gravity describes the gravitational interaction without requiring any of the equivalence principle versions. The replacement of general relativity by teleparallel gravity may, in consequence, lead to a conceptual reconciliation of gravitation with quantum mechanics. © 2006 American Institute of Physics.

Ghost free dual vector theories in 2 + 1 dimensions

We explore here the issue of duality versus spectrum equivalence in dual theories generated through the master action approach. Specifically we examine a generalized self-dual (GSD) model where a Maxwell term is added to the self-dual model. A gauge embedding procedure applied to the GSD model leads to a Maxwell-Chern-Simons (MCS) theory with higher derivatives. We show here that the latter contains a ghost mode contrary to the original GSD model. By figuring out the origin of the ghost we are able to suggest a new master action which interpolates between the local GSD model and a nonlocal MCS model. Those models share the same spectrum and are ghost free. Furthermore, there is a dual map between both theories at classical level which survives quantum correlation functions up to contact terms. The remarks made here may be relevant for other applications of the master action approach. © SISSA 2006.

Daily activity resources collection by the swarm-founding wasp Angiopolybia pallens (Hymenoptera: Vespidae)

Angiopolybia pallens (Lepeletier, 1836) exhibited an intense activity at the beginning (6:00-7:00 a.m.) and end of the day (5:30-6:00 p.m.) (bimodal daily activity) and a low efficiency index in resources collection. The species also exhibited an equivalence relation in the items collected (nectar, prey and pulp) and a negative reaction to temperature and luminosity increasing, and reacted positively to an increase in the relative air humidity.

Um modelo para orientação de imagens orbitais baseado em feições retas

The aim of this paper is to present a model for orientation of pushbroom sensors that allows estimating the polynomial coefficients describing the trajectory of the platform, using linear features as ground control. Considering that pushbroom image acquisition is not instantaneous, six EOP (Exterior Orientation Parameters) for each scanned line must be estimated. The sensor position and attitude parameters are modeled with a time dependent polynomial. The relationship between object and image space is established through a mathematical model based on the equivalence between the vector normal to the projection plane in the image space and to the vector normal to the rotated projection plane in the object space. The equivalence property between planes was adapted to consider the pushbroom geometry. Some experiments with simulated data corresponding to CBERS scene (China-Brazil Earth Resource Satellite) were accomplished in order to test the developed model using straight lines. Moreover, experiments with points ground with the model based on collinearity equations adapted to the pushbroom geometry were also accomplished. The obtained results showed that the proposed model can be used to estimate the EOP of pushbroom images with suitable accuracy.

Jacobi script v sign-functions and discrete Fourier transforms

Properties of the Jacobi script v sign3-function and its derivatives under discrete Fourier transforms are investigated, and several interesting results are obtained. The role of modulo N equivalence classes in the theory of script v sign-functions is stressed. An important conjecture is studied. © 2006 American Institute of Physics.

Bringing together gravity and the quanta

Due to its underlying gauge structure, teleparallel gravity achieves a separation between inertial and gravitational effects. It can, in consequence, describe the isolated gravitational interaction without resorting to the equivalence principle, and is able to provide a tensorial definition for the energy-momentum density of the gravitational field. Considering the conceptual conflict between the local equivalence principle and the nonlocal uncertainty principle, the replacement of general relativity by its teleparallel equivalent can be considered an important step towards a prospective reconciliation between gravitation and quantum mechanics. © 2006 American Institute of Physics.

The influence of the flame structure on the combustion oscillations in a cylindrical chamber

An experimental study has been conducted with the objective of investigating the effects of the flame structure in the combustion oscillation conditions into a laboratorial scale cylindrical chamber. The experiments were conducted in a water-jacketed 1-m long by 25-cm internal diameter stainless steel vertical tube. The combustor operated with liquefied petroleum gas (LPG) in both oscillatory and non oscillatory conditions, under the same input conditions. Part of the reactant mixture was excited acoustically, before the burner exit, by a speaker positioned strategically. The burner was aligned with the chamber longitudinal axis and positioned at its bottom. The experiments were conducted for 0.16 g/s of LPG burning in stoichiometric equivalence ratio. To analyze the flame structure the image tomographic reconstruction process were used, and the resultant images were associated to the oscillatory conditions (frequency and amplitude) into the combustion chamber. The main conclusions were: 1) when the flame premixed condition increase, for example 60% of the total air flow rate is premixed with LPG, the region of intense energy released is close to burner exit and strong amplitudes of oscillation (close to 50 mbar) were obtained into the chamber; 2) for long flames, predominantly diffusive flames, just weak amplitudes were detected, in the spite of the speaker exiting the premixed flow; 3) when the energy is released distributed through the combustion chamber, the long flame acts like a baffle. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Farmacovigilância no Brasil: A relação entre polimorfismo de fármacos, efetividade e segurança dos medicamentos

In spite of the stated Brazilian policy on medicines that their quality, effectiveness and safety should be ensured at reasonable cost, hospitals in the ANVISA Surveillance Network have been receiving notifications of technical complaints, adverse reactions and suspected therapeutic ineffectiveness (STI) of medicines. The purpose of this study was to identify the medicines notified for suspicion of therapeutic ineffectiveness, at a university hospital participating in the national Surveillance Network, and to investigate the existence of polymorphs of any of the drugs involved, by examining the literature. There were 31 notifications of STI in a period of 18 months, concerning 11 different drugs, all of which were 'similar' drugs (neither original nor licensed by originator); five of these could contain polymorphs, according to the literature. However, this does not mean that the other drugs could not contain some unknown polymorphs, more studies being needed on polymorphism, especially in the cases of reported therapeutic ineffectiveness. Therefore, tests of polymorphism should be made part of the routine quality control of the raw materials during the development of medicines and in the studies of pharmaceutical equivalence to 'reference' medicines (innovative brands). The stability test should also involve a study of polymorphism, in order to confirm the solid state stability of the drug. All these measures will assure the effectiveness of medicines, since the reproducibility in the quality of pharmaceutical products could be monitored, as well as the equivalence of each production batch with the batch selected to determine the bioequivalence with the reference brand.

Tributación en América Latina: en busca de una nueva agenda de reformas

Incluye Bibliografía

Globalization and development

Includes bibliography