Theory of Andreev reflection in a two-orbital model of iron-pnictide superconductors

A recently developed theory for the problem of Andreev reflection between a normal metal (N) and a multiband superconductor (MBS) assumes that the incident wave from the normal metal is coherently transmitted through several bands inside the superconductor. Such splitting of the probability amplitude into several channels is the analogue of a quantum waveguide. Thus, the appropriate matching conditions for the wave function at the N/MBS interface are derived from an extension of quantum waveguide theory. Interference effects between the transmitted waves inside the superconductor manifest themselves in the conductance. We provide results for a FeAs superconductor, in the framework of a recently proposed effective two-band model and two recently proposed gap symmetries: in the sign-reversed s-wave ($\Delta\cos(k_x)\cos(k_y)$) scenario resonant transmission through surface Andreev bound states (ABS) at nonzero energy is found as well as destructive interference effects that produce zeros in the conductance; in the extended s-wave ($\Delta[\cos(k_x)+\cos(k_y)]$) scenario no ABS at finite energy are found.Comment: 4 pages, 5 figure

O gênero Burkholderia: um importante componente da comunidade microbiana.

Descrição do gênero Burkholderia; Distribuição e diversidade; Patógenos em seres humanos e animais; Patógenos em plantas; Espécies diazotróficas em plantas não leguminosas; Espécies diazotróficas em plantas leguminosas; Promoção de crescimento em plantas; Controle biológico de doenças em plantas; Biorremediação.bitstream/CNPAB-2010/33991/1/doc219.pd

Nutrição mineral do algodoeiro herbáceo colorido BRS rubi adubado com esterco bovino como fonte de macronutrientes.

A utilização no solo de fontes alternativas de nutrientes às plantas, como o esterco bovino, é muito importante, pois permite ao pequeno agricultor adquirir, dentro de sua propriedade, insumos para aumento de sua produção sem gastos adicionais. O objetivo desse trabalho foi verificar a nutrição mineral de plantas de algodoeiro herbáceo colorido BRS Rubi adubado com esterco bovino para o suprimento de macronutrientes. O experimento foi conduzido na comunidade São Pedro, município de Itaporanga, PB, situado na mesorregião do Sertão Paraibano, no período de 07 de outubro 2008 a 17 de janeiro de 2009

A Comparative Evaluation of Two Distributed Hydro-Sedimentological Models in The Semiarid Region of the State of Paraíba, Brazil

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Hands-on in the school pond!

The current sense of climate urgency poses significant challenges to the general population and, as a result, to schools. Environmental Education has a structuring importance in this context, taking into account its curricular transversality, focusing on the promotion of attitudes, values, and skills necessary to respond to the emergency situation revealed by several studies and international communications. Natural Sciences curriculum guidelines emphasize the importance of science in everyday life, with applications in technology, society, and the environment. Problems/questions can emerge to guide learning when contextualized in real-life and current situations. They contribute significantly to the development of skills such as "reasoning and problem solving," "critical thinking and creative thinking," "scientific, technical, and technological knowledge and literacy" and "well-being, health, and environment