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

Field and greenhouse inoculation methods for assessment of sheath blight resistance in rice.

Field and greenhouse inoculation methods were compared to determine the genetic variation for resistance to Rhizoctonia solani in 38 somaclones of rice cultivar Metica-1. Rice plants in pots were inoculated with isolate 4F1 at the age of sixty four days, with 2.0 g of the fungal culture, multiplied on rice grain and hull medium and placed on the soil surface around the plant. The differences among somaclones in relation to lesion height were significant and varied from 6.5 to 15.5 cm. In the field trial of artificial inoculation with fungal culture, 52 days after planting, the lesion height varied from 6.2 to 17.7 cm. The correlation between disease severity in the greenhouse and the field was positive and highly significant (r=0.44; P< 0.01), indicating the greenhouse inoculation as a safe method for screening germplasm for sheath blight resistance.Nota técnica

Identification of RAPD marker linked to blast resistance gene in a somaclone of rice cultivar Araguaia.

O gene Pi-ar confere resistência para a raça IB-45 de Pyricularia grisea no somaclone derivado de panículas imaturas da cultivar de arroz (Oryza sativa) Araguaia. A técnica RAPD foi usada para identificar marcadores ligados a este gene utilizando a análise de misturas segregantes. Inicialmente o DNA do pai doador resistente SC09 e da cultivar Araguaia foram analisados usando primers arbitrários. Dos 240 primers, 203 produziram produtos amplificados. O DNA dos pais e dos bulks resistente e suscetível da população F2 foram testados usando 48 primers que diferenciaram os pais resistente e suscetível. Enquanto oito primers diferenciaram o bulk resistente do suscetível bem como o somaclone SC09 e Araguaia, somente o primer OPC02 ('GTGAGGCGTC') estava fortemente ligado (1,7cM) ao gene de resistência do somaclone SC09

Escolas rurais produzem hortaliças e frutas utilizando água de chuva armazenada em cisterna: estudo de caso.

O sucesso do programa de cisterna armazenando água de chuva para atender ao consumo das famílias no semiárido brasileiro permitiu que essa tecnologia fosse também utilizada para produzir alimentos, visando à melhoria da dieta das famílias rurais, denominado por P1+2 ou ?cisterna de produção?. Essa experiência foi implementada em 43 escolas rurais de treze municípios do Estado da Bahia. Assim, esta pesquisa teve por objetivo identificar as práticas agrícolas executadas nas áreas das hortas e ou pomar, como subsídios à instalação de novas cisternas em escolas de outros municípios. Também, verificar como a produção está sendo inserida na alimentação oferecida aos alunos. O diagnóstico feito a partir de visitas às escolas aponta para a necessidade de ajustes no sistema cisterna-horta, visando sua maior eficiência e permitindo a melhoria da disponibilidade e qualidade dos alimentos servidos.nas escola

Degradabilidade ruminal da palma forrageira e do atriplex em bovinos.

Este trabalho avaliou a influência de dietas contendo substituições parciais da palma forrageira pela atriplex sobre a degradabilidade ruminal da matéria seca e fibra em detergente neutro do feno de atriplex e da palma forrageira em bovinos

Enhanced propagation of motile bacteria on surfaces due to forward scattering

How motile bacteria move near a surface is a problem of fundamental biophysical interest and is key to the emergence of several phenomena of biological, ecological and medical relevance, including biofilm formation. Solid boundaries can strongly influence a cell's propulsion mechanism, thus leading many flagellated bacteria to describe long circular trajectories stably entrapped by the surface. Experimental studies on near-surface bacterial motility have, however, neglected the fact that real environments have typical microstructures varying on the scale of the cells' motion. Here, we show that micro-obstacles influence the propagation of peritrichously flagellated bacteria on a flat surface in a non-monotonic way. Instead of hindering it, an optimal, relatively low obstacle density can significantly enhance cells' propagation on surfaces due to individual forward-scattering events. This finding provides insight on the emerging dynamics of chiral active matter in complex environments and inspires possible routes to control microbial ecology in natural habitats

Finding a Spherically Symmetric Cosmology from Observations in Observational Coordinates -- Advantages and Challenges

One of the continuing challenges in cosmology has been to determine the large-scale space-time metric from observations with a minimum of assumptions -- without, for instance, assuming that the universe is almost Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW). If we are lucky enough this would be a way of demonstrating that our universe is FLRW, instead of presupposing it or simply showing that the observations are consistent with FLRW. Showing how to do this within the more general spherically symmetric, inhomogeneous space-time framework takes us a long way towards fulfilling this goal. In recent work researchers have shown how this can be done both in the traditional Lema\^{i}tre-Tolman-Bondi (LTB) 3 + 1 coordinate framework, and in the observational coordinate (OC) framework. In this paper we investigate the stability of solutions, and the use of data in the OC field equations including their time evolution and compare both approaches with respect to the singularity problem at the maximum of the angular-diameter distance, the stability of solutions, and the use of data in the field equations. This allows a more detailed account and assessment of the OC integration procedure, and enables a comparison of the relative advantages of the two equivalent solution frameworks. Both formulations and integration procedures should, in principle, lead to the same results. However, as we show in this paper, the OC procedure manifests certain advantages, particularly in the avoidance of coordinate singularities at the maximum of the angular-diameter distance, and in the stability of the solutions obtained. This particular feature is what allows us to do the best fitting of the data to smooth data functions and the possibility of constructing analytic solutions to the field equations.Comment: 31 page