Frequency upconversion in a Pr(3+) doped chalcogenide glass containing silver nanoparticles

We report on orange-to-blue frequency upconversion (UC) in Pr(3+) doped chalcogenide glass (Ga(10)Ge(25)S(65)) doped with Ag(2)S and heat treated under different conditions to nucleate silver nanoparticles (NPs). The experiments were performed using 7 ns pulses from a dye laser that operates at similar to 590 nm, in resonance with the (3)H(4)->(1)D(2) transition of Pr(3+) ions. The enhancement observed in the UC emission at similar to 494 nm, ascribed as (3)P(0)->(3)H(4) transition of the Pr(3+) ion, is attributed to the large local field acting on the emitting ions due to the presence of the metallic NPs. (C) 2008 American Institute of Physics.

Enhanced luminescence of Tb3+/Eu3+ doped tellurium oxide glass containing silver nanostructures

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Luminescence Enhancement of Carboxyl-Coated CdTe Quantum Dots by Silver Nanoparticles

Metallic nanoparticles (NPs) have been used to improve the sensibility of biosensors and bioassays either by enhancing radiative emission or inducing quenching process on fluorescent probes. The aim of this research was to study the interaction of silver and silver-pectin NPs with water-dispersed carboxyl-coated cadmium telluride (CdTe) quantum dots (QDs). Metallic NPs were observed to change the emission of these fluorophores through local field effects. In a solution-base platform, an increase of 82 % was observed for the CdTe emission due to the interaction of QDs and silver-pectin NPs. QDs interaction with silver NPs without pectin was also investigated and a smaller emission enhancement of 20 % was detected. We observed that the NPs' nature and QDs' surface charge and concentration are important parameters for NPs-QDs interaction. Moreover, the presence of the pectin polymer shows to be a key component to the observed fluorescence enhancement. © 2013 Springer Science+Business Media New York.

Massive spin-2 particle from a rank-2 tensor

Here we obtain all possible second-order theories for a rank-2 tensor which describe a massive spin-2 particle. We start with a general second-order Lagrangian with ten real parameters. The absence of lower-spin modes and the existence of two local field redefinitions leads us to only one free parameter. The solutions are split into three one-parameter classes according to the local symmetries of the massless limit. In the class which contains the usual massive Fierz-Pauli theory, the subset of spin-1 massless symmetries is maximal. In another class where the subset of spin-0 symmetries is maximal, the massless theory is invariant under Weyl transformations and the mass term does not need to fit into the form of the Fierz-Pauli mass term. In the remaining third class neither the spin-1 nor the spin-0 symmetry is maximal and we have a new family of spin-2 massive theories. © 2013 American Physical Society.

Note on the nonuniqueness of the massive Fierz-Pauli theory and spectator fields

It is possible to show that there are three independent families of models describing a massive spin-2 particle via a rank-2 tensor. One of them contains the massive Fierz-Pauli model, the only case described by a symmetric tensor. The three families have different local symmetries in the massless limit and can not be interconnected by any local field redefinition. We show here, however, that they can be related with the help of a decoupled and nondynamic (spectator) field. The spectator field may be either an antisymmetric tensor B μν=-Bνμ, a vector Aμ or a scalar field φ, corresponding to each of the three families. The addition of the extra field allows us to formulate master actions which interpolate between the symmetric Fierz-Pauli theory and the other models. We argue that massive gravity models based on the Fierz-Pauli theory are not expected to be equivalent to possible local self-interacting theories built up on top of the two new families of massive spin-2 models. The approach used here may be useful to investigate dual (nonsymmetric) formulations of higher-spin particles. © 2013 American Physical Society.

Seleção de plantas hospedeiras pela aranha bromelícola Psecas chapoda (Salticidae)

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

As pesquisas sobre educação em museus e centros de ciências no Brasil: estudo descritivo e analítico da produção acadêmica

Pós-graduação em Educação para a Ciência - FC

Análise das produções bibliográficas sobre trabalho infantil e educação no período de 2002 a 2012

Pós-graduação em Educação - FCT

A autonomia no contexto Teletandem institucinal integrado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Tsukamoto s Theorem in Characteristic two

In this paper it is proved that hermitian forms over quaternion division algebras over local fields of characteristic two are classified by their dimension and discriminant.

Estudo para correção dos sensores da rede de monitoramento do campo elétrico em função do campo elétrico de tempo bom

A monitoring network of atmospheric electric field covering the Vale do Paraiba region was implemented. The sensors were located on different sites with different altitude and geographic topology. The present work reports the study carried on those sensors in order to verify the necessity of using some correction factor to the measured local electric field intensity due to effects of local environment. The measurements were done in continuous 24 hours per day with the data recorded on registers in each device accumulating information during a period of four months. The relation between the electric field values by each sensor was compared to the reference located on Sao Jose dos Campos city using the same period. In a graphical analysis using the local field intensity and the reference, the data were fitted to a straight line obtained by minimum square method. Variation up to 95% was observed between the field values in some sensors. Another method was proposed, comparing the mean values of the electric field in a function of time. The variation in some sensors reached up to 133%. We conclude that the variations are due to local atmospheric conditions and no correction factor is required on the electric field sensors

El gobierno de las megalópolis, el caso de Brasil, São Paulo: gestión metropolitana, descentralización y participación como desafíos simultáneos

The government of a megalopolis, such as São Paulo, shows singular challenges that do not exist in less complex urban contexts. Being a city of a country with a recent industrialized economy, with an income (functional and geographical) highly concentrated, that has resumed the democracy for only one quarter of a century, this megacity lives with its own political and organizational assignments, due to the contradictory character of the political behavior of its habitants/ voters and of the traditionalist nature of populism and patronage in the relationship between the rulers and the ruled and between the Executive and Legislative powers at the local level. In such context, the difficulties to prosecute the assignments of the metropolitan organization, the decentralization and the institutionalization of citizen participatory channels in the governance and administrative activities are huge. The centrifuge forces (of the decentralization of the local government, through subprefectures), the centripetal forces ( of the metropolitan organization process) and the diffuse forces (of the claiming popular participation) act simultaneously over the deciding processes, in São Paulo, receiving, still, state and national political influences, since the city is a very significant historically producer of political and electoral capital. The analysis of the recent experience of the creation of the subprefectures and the representative counsels (fixed in the Municipality Organic Law of 1990) and the attempt to implement the participatory budgeting, in two occasions (1989-1992 and 2001-2004), reveal some of the social and political reasons that make difficult the establishment of a solidly democratic governance and of a more efficient public administration in the metropolitan area of São Paulo.

O mapa de ponta-cabeça

Joaquin Torres Garcia reversed the position of the map of the continent, reaching South America north. This little drawing illustrates an article by Torres García, 1935, in which he advocates the creation of a "Escuela del Sur". This image illustrates a need in Latin America to seek their own ways. Torres-Garcia was inspired by the preColumbian American heritage for their symbolic and Constructivism proposes that Latin America look to the popular ancestral and cultural traditions and build an art itself through which the continent would no longer be a tributary of European culture. As production visual modern and contemporary Latin American context of globalization, takes the center / periphery relationship? The colonizer's model center/periphery relationship persists in the Latin American visual production? The technologies offered other ways of representation that break with the culture of repetition? These questions guide our research.

The influence of visual stimuli in ethnobotanical data collection using the listing task method

The listing task, a method used in social and behavioral sciences, is frequently used in ethnobotanical research to constructfolk taxonomies and select relevant itemsfor subsequent research. The objective of the present study was to determine whether visual stimuli are associated with responses to the theme plants or if context influences the answers. Interviews were conducted with 400 women in Rio Claro, São Paulo, Brazil, in four different locations: three with a visible presence of plants (a plant store, a supermarket, and a public plaza) and one with no plants (a street corner in the center of the city). The women were asked to name plants. Analysis indicates that visual stimuli influenced responses and that this is more marked in the plant store than in the other locations. The plants cited most often-roses, orchids, ferns, violets, and daisies-were, with little variation, the same in all the locales studied.

O Uso da informação visual global e local no controle da postura e do timing durante a tarefa de agarrar um objeto em aproximação

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