Quantum Critical Point in the Spin Glass-Kondo Transition in Heavy Fermion Systems

The Kondo-Spin Glass competition is studied in a theoretical model of a Kondo lattice with an intra-site Kondo type exchange interaction treated within the mean field approximation, an inter-site quantum Ising exchange interaction with random couplings among localized spins and an additional transverse field in the x direction, which represents a simple quantum mechanism of spin flipping. We obtain two second order transition lines from the spin-glass state to the paramagnetic one and then to the Kondo state. For a reasonable set of the different parameters, the two second order transition lines do not intersect and end in two distinct QCP.Comment: 20 pages; 1 figure; to appear in Physical Review

Ultrastable lasers based on vibration insensitive cavities

We present two ultra-stable lasers based on two vibration insensitive cavity designs, one with vertical optical axis geometry, the other horizontal. Ultra-stable cavities are constructed with fused silica mirror substrates, shown to decrease the thermal noise limit, in order to improve the frequency stability over previous designs. Vibration sensitivity components measured are equal to or better than 1.5e-11 per m.s^-2 for each spatial direction, which shows significant improvement over previous studies. We have tested the very low dependence on the position of the cavity support points, in order to establish that our designs eliminate the need for fine tuning to achieve extremely low vibration sensitivity. Relative frequency measurements show that at least one of the stabilized lasers has a stability better than 5.6e-16 at 1 second, which is the best result obtained for this length of cavity.Comment: 8 pages 12 figure

Computational system for geostatistical analysis.

ABSTRACT: Geostatistics identifies the spatial structure of variables representing several phenomena and its use is becoming more intense in agricultural activities. This paper describes a computer program, based on Windows Interfaces (Borland Delphi), which performs spatial analyses of datasets through geostatistic tools: Classical statistical calculations, average, cross- and directional semivariograms, simple kriging estimates and jackknifing calculations. A published dataset of soil Carbon and Nitrogen was used to validate the system. The system was useful for the geostatistical analysis process, for the manipulation of the computational routines in a MS-DOS environment. The Windows development approach allowed the user to model the semivariogram graphically with a major degree of interaction, functionality rarely available in similar programs. Given its characteristic of quick prototypation and simplicity when incorporating correlated routines, the Delphi environment presents the main advantage of permitting the evolution of this system

Variabilidade espacial de atributos do solo e produtividade da cultura de cana-de-açúcar em relação a localização topográfica

Soils submitted to the same management system in places with little variation of landscape, manifest differentiated spatial variability of their attributes and crop yield. The aim of this work was to investigate the correlation between spatial variability of the soil attributes and sugarcane yield as a result of soil topography. To achieve this objective, a test area of 42 ha located at the São João Sugar Mill, in Araras, in the State of São Paulo, Brazil, was selected. Sugarcane yield was measured with a yield monitor fitted in a sugarcane harvester and GPS signal. A total of 170 soil samples were taken at regular 50 m grid, at a depth of 0 - 0.2 m. The area under study was divided into two sites based on topography. The following soil attributes were analysed: organic matter (OM) content, exchangeable potassium (K), calcium (Ca) and magnesium (Mg), their base saturation percentage (%BS), cation exchange capacity (CEC), pH, clay, silt, total sand and density. The use of landscape and geostatistics enable defining areas with different spatial variability in soil attributes and crop yield, providing the visualization and definition of homogeneous management zones. The largest spatial variability of soil attributes and sugarcane yield was in the lowest part of the field.Solos submetidos ao mesmo sistema de manejo em locais com pequena variação de relevo manifestam variabilidade espacial diferenciada de atributos do solo e das plantas. Objetivou-se com este trabalho estudar a correlação entre a variabilidade espacial de atributos físicos e químicos do solo com a produtividade da cana-de-açúcar em duas posições do relevo, de acordo com a topografia da área. O estudo foi realizado no município de Araras, SP, em uma área de 42 ha, pertencente à Usina São João. Para o mapeamento da produtividade da cultura da cana-de-açúcar utilizou-se um monitor de produtividade acoplado à colhedora e ao sinal de GPS. Coletaram-se 170 amostras do solo, em uma malha regular de 50 m entre pontos, na profundidade de 0,0 - 0,2 m. O talhão de estudo foi dividido em duas áreas menores, segundo a topografia. Os atributos do solo avaliados foram: teor de matéria orgânica (MO), potássio (K), cálcio (Ca), magnésio (Mg), saturação por bases (V%), capacidade de troca catiônica (CTC), pH, argila, silte, areia total e densidade. O uso do relevo e da geoestatística possibilitou definir áreas com diferentes variabilidades espaciais para atributos do solo e produtividade da cultura de cana-de-açúcar, proporcionando a visualização e definição de zonas homogêneas de manejo de acordo com o relevo. A maior variabilidade espacial de atributos do solo e a produtividade da cultura de cana-de-açúcar ocorreram na parte mais baixa do talhão.1250125

Proposta de dispositivo para aplicação de reguladores de crescimento à taxa variada e em tempo real para a cultura do algodão.

Fitorreguladores são utilizados para controlar a arquitetura da planta de algodão, uma vez que permitem aumentar a produtividade, além de manter a altura do algodoeiro em tamanho adequado para a colheita mecanizada. O objetivo principal desse projeto é propor e desenvolver um protótipo de dispositivo capaz de realizar aplicações à taxa variada em tempo real dos reguladores de crescimento.SBIAgro 2007

Contribuição da pesquisa de melhoramento genético para elevação da produtividade da lavoura arrozeira do Rio Grande do Sul.

Este trabalho visa quantificar a contribuição dos programas de melhoramento genético de arroz irrigado do IRGA e da Embrapa para o caráter rendimento de grãos no período de 1983 (safra 1982/83) a 2011 (safra 2010/11)

Produtividade e composição bromatológica de híbridos de sorgo cultivados em sistema agrossilvipastoril no semiárido.

Resumo: O uso de sistema integrados de produção e conservação de forragens são estratégias para aumentar a oferta de forragem no semiárido. O sorgo é uma planta indicada para a produção de silagem em regiões secas por apresentar tolerância ao estresse hídrico e qualidade nutricional. Objetivou-se avaliar a produtividade e qualidade bromatológica de 25 híbridos de sorgo cultivados em sistema agrossilvipastoril no Ceará. Foram determinados os teores de matéria seca, protéina, cinzas, extrato etéreo, fibra em detergente ácido e neutro, lignina, hemicelulose e celulose. Houve diferença entre os híbridos, com destaque para H22 que apresentou a melhor produtividade e a melhor qualidade nutricional. [Productivity and Bromatological composition of sorghum hybrids grown in agrosylvopastoral system in semiarid]. Abstract: The use of forage integrated system production and conservation are important strategies to increase animal food supply in semiarid. Sorghum is indicated to silage production in the dry areas due to its tolerance to water stress and nutritional quality. The aimed of this research was to evaluate the productivity and chemical quality of 25 sorghum hybrids grown in an agrosilvopastoral system in Ceará. It was determinated dry matter, protein, ash, ether extract, neutral and acid detergent fiber, lignin, hemicellulose and cellulose contents. There were differences among the hybrids, where H22 showed the best productivity and nutritional quality

Ganho genético em potencial produtivo do arroz irrigado no Rio Grande do Sul, após o lançamento da cultivar BR-IRGA 409.

Este trabalho teve como objetivo estimar os ganhos genéticos em rendimento de grãos nos últimos 30 anos, ou a partir do lançamento da cultivar BR-IRGA 409, no estado do Rio Grande do Sul, com base no desempenho de cultivares representativas lançadas pela pesquisa

Delamination analysis after carbon/epoxy plate drilling

Drilling of carbon fibre reinforced plates CFRP causes typical damages such as delamination and others. These damages, that cannot be visually detected, can cause the premature collapse of structures. Damage assessment is usually carried out using non-destructive inspections like radiography and ultrasonic C-scan.Damage extent can be evaluated by the use of damage criteria. One of them delamination factor was proposed by Chen, establishing a ratio between the maximum damaged diameter and the hole nominal diameter. Another one damage ratio was presented by Mehta comparing the damaged area with the hole average area. Both ratios allow for comparison between different drilling conditions.In this paper the images obtained are processed and analyzed using standard techniques from Computational Vision together with a processing platform already developed. An experimental evaluation using radiographic and C-scan images to obtain the referred ratios will be presented