Generalized squeezing operators, bipartite Wigner functions and entanglement via Wehrl's entropy functionals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A new proposal for the picture changing operators in the minimal pure spinor formalism

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

New class of spin projection operators for 3D models

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ladder operators for subtle hidden shape-invariant potentials

Ladder operators can be constructed for all potentials that present the integrability condition known as shape invariance, satisfied by most of the exactly solvable potentials. Using the superalgebra of supersymmetric quantum mechanics, we construct the ladder operators for two exactly solvable potentials that present a subtle hidden shape invariance.

Comments on spin operators and spin-polarization states of 2+1 fermions

In this brief article we discuss spin-polarization operators and spin-polarization states of 2 + 1 massive Dirac fermions and find a convenient representation by the help of 4-spinors for their description. We stress that in particular the use of such a representation allows us to introduce the conserved covariant spin operator in the 2 + 1 field theory. Another advantage of this representation is related to the pseudoclassical limit of the theory. Indeed, quantization of the pseudoclassical model of a spinning particle in 2 + 1 dimensions leads to the 4-spinor representation as the adequate realization of the operator algebra, where the corresponding operator of a first-class constraint, which cannot be gauged out by imposing the gauge condition, is just the covariant operator previously introduced in the quantum theory.

Dynamics in discrete phase spaces and time interval operators

The von Neumann-Liouville time evolution equation is represented in a discrete quantum phase space. The mapped Liouville operator and the corresponding Wigner function are explicitly written for the problem of a magnetic moment interacting with a magnetic field and the precessing solution is found. The propagator is also discussed and a time interval operator, associated to a unitary operator which shifts the energy levels in the Zeeman spectrum, is introduced. This operator is associated to the particular dynamical process and is not the continuous parameter describing the time evolution. The pair of unitary operators which shifts the time and energy is shown to obey the Weyl-Schwinger algebra. (C) 1999 Elsevier B.V. B.V. All rights reserved.

TOURISM IN CAVES and THE CONSERVATION of THE SPELEOLOGICAL HERITAGE: THE CASE of SERRA da BODOQUENA (MATO GROSSO do SUL STATE, BRAZIL)

Heros Augusto Santos Lobo & Edvaldo Cesar Moretti: Tourism in Caves and the Conservation of the Speleological Heritage: The case of Serra da Bodoquena (Mato Grosso do Sul State, Brazil)The Serra da Bodoquena is the region in the state of Mato Grosso do Sul, Brazil in which the Municipality of Bonito is located. This municipality is the primary calling card for tourism in the state and is one of the most developed areas of ecotourism and speleotourism in the country The tourism there is entitled ecotourism, and is designed to be sustainable. The present case study focuses on the ecologically Sustainable aspects of the spleotourism practiced there, especially the proposals for tourist carrying capacity adopted. The results and discussion provide Suggestions for the adoption of a different formulation of carrying capacity focusing on both operational and quantitative aspects. Ecologically Sustainable speleotourism in the Serra da Bodoquena should be possible as long as new proposals limiting visitation are adopted which conform to technical environmental management procedures and consider the interests of local stakeholders.

Vertex operators and Jordan fields

The construction of Lie algebras in terms of Jordan algebra generators is discussed. The key to the construction is the triality relation already incorporated into matrix products. A generalisation to Kac-Moody algebras in terms of vertex operators is proposed and may provide a clue for the construction of new representations of Kac-Moody algebras in terms of Jordan fields. © 1988.

Conservation laws for non-potential operators

A study was developed in order to build a function M invariant in time, by means of Hamiltonian's formulation, taking into account the equation associated to the problem, showing that starting from this function the equation of motion of the system with the contour conditions for non-conservative considered problems can be obtained. The Hamiltonian method is extended for these kind of systems in order to validate for non-potential operators through variational approach.

Generalized ladder operators for shape-invariant potentials

A general form for ladder operators is used to construct a method to solve bound-state Schrödinger equations. The characteristics of supersymmetry and shape invariance of the system are the start point of the approach. To show the elegance and the utility of the method we use it to obtain energy spectra and eigenfunctions for the one-dimensional harmonic oscillator and Morse potentials and for the radial harmonic oscillator and Coulomb potentials.

Gender, tourism, and participatory appraisals at the Corumbau Marine Extractive Reserve, Brazil

The Corumbau Marine Extractive Reserve was created in a region of rich biodiversity, located in the South of Bahia State, Brazil, to meet the revindications of artisanal fishermen in a context of increasing predatory industrial fisheries. The aim of the Marine Extractive Reserve is to improve the sustainability of fisheries stocks and the economy of artisanal fishermen's families, protecting the local biodiversity for the locals' collective use. However, at Corumbau the natives are facing social problems that have increased due to tourism growth. The present research contributes to the Management Plan in sectors that are crucial to assess the aspirations and subjective aspects related to the natives' daily life at individual, familiar and communitary levels. The Participatory Appraisal with a Gender Equity Perspective (PAGP) was applied to five communities at RESEX Corumbau, showing, by gender, the greatest problems artisanal fisheries' families are facing. Tourism is growing in the area, reflecting the residents different and contradictory interests. It can develop commerce and jobs, but also intensify some social and environmental problems in this area. © Society for Human Ecology.

Tourism for whom?: Different paths to development and alternative experiments in Brazil

The tourism policies pursued by the Brazilian government since the 1990s have not produced the benefits that were expected from mass tourism. The example of two very successful cases of community-based tourism, stressing paths rooted in a development model that is fair and environmentally responsible, shows that tourism development can improve the quality of life in communities that receive an influx of tourists provided that the local community is taken into account and the planning and implementation of such development focus on creating opportunities and benefits for its members. © 2008 Latin American Perpectives.

Innovation in the tourism sector: a case study from the Commonwealth of Dominica

Includes bibliography

Regional environmental policy and sustainable tourism development in the Caribbean

Includes bibliography