VOICES FROM THE SOUTH: DIALOGICAL RELATIONSHIPS AND COLLABORATION IN MATHEMATICS EDUCATION

This chapter presents a collaborative experience between two neighbouring countries from South America: Argentina and Brazil. Our purpose is to share a model of international collaboration that we consider to be an alternative to the classical movement of early mathematical and scientific knowledge between East and West and between North and South. We start our chapter with a general discussion about the phenomenon of globalization considering some local examples. We characterize our collaboration exploring the tensions and difficulties we faced along our own professional development at the local as well as the international level. We describe the development of our prior collaborative work that established the foundation for our international collaboration portraying the local mathematics education communities. We refer to some balances that were created among our relationships, the expansion of our collaborative network, and how this particular collaboration allows us to contribute to the regional field and inform the international one. We discuss the way that the search for balance and symmetry, or at least a complementary asymmetry in our collaborative relationships, has led us to generate a genuine and equitable collaboration.

On the picture dependence of Ramond-Ramond cohomology

Closed string physical states are BRST cohomology classes computed on the space of states annihilated by b- 0. Since b- 0 does not commute with the operations of picture changing, BRST cohomologies at different pictures need not agree. We show explicitly that Ramond-Ramond (RR) zero-momentum physical states are inequivalent at different pictures, and prove that non-zero-momentum physical states are equivalent in all pictures. We find that D-brane states represent BRST classes that are non-polynomial on the superghost zero-modes, while RR gauge fields appear as polynomial BRST classes. We also prove that in x-cohomology, the cohomology where the zero-mode of the spatial coordinates is included, there is a unique ghost-number one BRST class responsible for the Green-Schwarz anomaly, and a unique ghost number minus one BRST class associated with RR charge. © 1998 Elsevier Science B.V.

Tachyon condensation in superstring field theory

It has been conjectured that at the stationary point of the tachyon potential for the D-brane-anti-D-brane pair or for the non-BPS D-brane of superstring theories, the negative energy density cancels the brane tensions. We study this conjecture using a Wess-Zumino-Witten-like open superstring field theory free of contact term divergences and recently shown to give 60% of the vacuum energy by condensation of the tachyon field alone. While the action is non-polynomial, the multiscalar tachyon potential to any fixed level involves only a finite number of interactions. We compute this potential to level three, obtaining 85% of the expected vacuum energy, a result consistent with convergence that can also be viewed as a successful test of the string field theory. The resulting effective tachyon potential is bounded below and has two degenerate global minima. We calculate the energy density of the kink solution interpolating between these minima finding good agreement with the tension of the D-brane of one lower dimension. © 2000 Elsevier Science B.V.

WZW-like action for heterotic string field theory

We complete the construction of the Neveu-Schwarz sector of heterotic string field theory begun in [9] by giving a closed-form expression for the action and gauge transformations. Just as the Wess-Zumino-Witten (WZW) action for open superstring field theory can be constructed from pure-gauge fields in bosonic open string field theory, our heterotic string field theory action is constructed from pure-gauge fields in bosonic closed string field theory. The construction involves a simple alternative form of the WZW action which is consistent with the algebraic structures of closed string field theory. © SISSA/ISAS 2004.

¿Cuán sustentable es la Región Metropolitana de Santiago?: metodologías de evaluación de la sustentabilidad

Incluye Bibliografía

Ecoeficiencia y desarrollo de infraestructura urbana sostenible en Asia y América Latina: revisión de marcos conceptuales y análisis de enfoques metodológicos para el desarrollo de una infraestructura urbana sostenible y ecoeficiente

Incluye bibliografía

El efecto de los errores censales en la estimacion de la migracion neta

Incluye Bibliografía

Consideraciones metematicas y practicas para la formulacion y seleccion de tasas de migracion

Incluye Bibliografía

The North-South dimension of the environmental and cleaner technology industries

Includes bibliography

La dimensión Norte-Sur de las industrias de limpieza ambiental y la difusión de tecnologías limpias

Incluye Bibliografía

Atitudes de condutores de atividades de aventura e a perspectiva de disseminação da sensibilização ambiental

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A VRBS no Cosme Velho: análise da presença da literatura latina em Memórias póstumas de Brás Cubas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Da agudeza às metáforas: romances de Antônio da Fonseca Soares

Pós-graduação em Letras - FCLAS

Caminho da fé: pedestrianismo, estados emocionais e reflexões sobre a ambiência

Pós-graduação em Ciências da Motricidade - IBRC

Etnomatemática: do ôntico ao ontológico. -

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)