Unstable and elusive superconductors

We briefly review earlier and report original experimental results in the context of metastable or possible superconducting materials. We show that applied electric field induces conducting state in Copper Chloride (CuCl) whose characteristics resemble behavior of sliding charge-density-wave(s) (CDW). We discuss whether the sliding CDW or collective transport of similar ordered charge phase(s) may account for the problem of "high-temperature superconductivity" observed in this and other materials, including Cadmium Sulfide (CdS), metal-ammonia solutions, polymers, amorphous carbon and tungsten oxides. We also discuss a local superconductivity that occurs at the surface of graphite and amorphous carbon under deposition of foreign atoms/molecules.Comment: Invited review article published in a special edition on Superconducting Materials in honor of the 95th birthday year of Ted Geballe, edited by M. B. Maple, J. Hirsch, and F. Marsigli

New Identities from a Combinatorial Approach to Generalized Fibonacci and Generalized Lucas Numbers

We present here some new identities for generalizations of Fibonacci and Lucas numbers by combinatorially interpreting these numbers in terms of numbers of certain tilings of a 1 x m board. As a consequence, some new interesting identities involving the ordinaries Fibonacci and Lucas numbers are derived.CNPqFed Univ Sao Paulo UNIFESP, Dept Sci & Technol, BR-12247014 Sao Jose Dos Campos, SP, BrazilFed Univ Sao Paulo UNIFESP, Dept Sci & Technol, BR-12247014 Sao Jose Dos Campos, SP, BrazilWeb of Scienc

Expografia moderna e contemporânea: Diálogos entre arte e arquitetura

SIAM. Series Iberoamericanas de Museología. Año 3, Vol.

A DESCENTRALIZAÇÃO NA GESTÃO DAS POLÍTICAS SOCIAIS NOS GOVERNOS NACIONAIS DO PT

Resumo Este trabalho objetiva compreender a descentralização no âmbito da gestão das políticas sociais nos governos nacionais do Partido dos Trabalhadores (PT), sobretudo de Luís Inácio Lula da Silva. Ao utilizar como recurso metodológico a pesquisa bibliográfica e documental, procura demonstrar que os governos nacionais vêm concebendo a descentralização como delegação de funções de gestão aos estados e municípios e/ou como uma estratégia de privatização dos serviços sociais. Assim, o trabalho busca demonstrar a manutenção da concentração do poder de decisão e de recursos financeiros na esfera do governo federal

Local and Global Superconductivity in Bismuth

We performed magnetization M(H,T) and magnetoresistance R(T,H) measurements on powdered (grain size ~ 149 micrometers) as well as highly oriented rhombohedral (A7) bismuth (Bi) samples consisting of single crystalline blocks of size ~ 1x1 mm2 in the plane perpendicular to the trigonal c-axis. The obtained results revealed the occurrence of (1) local superconductivity in powdered samples with Tc(0) = 8.75 \pm 0.05 K, and (2) global superconductivity at Tc(0) = 7.3 \pm 0.1 K in polycrystalline Bi triggered by low-resistance Ohmic contacts with silver (Ag) normal metal. The results provide evidence that the superconductivity in Bi is localized in a tiny volume fraction, probably at intergrain or Ag/Bi interfaces. On the other hand, the occurrence of global superconductivity observed for polycrystalline Bi can be accounted for by enhancement of the superconducting order parameter phase stiffness induced by the normal metal contacts, the scenario proposed in the context of "pseudogap regime" in cuprates [E. Berg et al., PRB 78, 094509 (2008)].Comment: 12 pages including 9 figures and 1 table, Special Issue to the 80th birthday anniversary of V. G. Peschansky, Electronic Properties of Conducting System