Circular photogalvanic effect at inter-band excitation in InN

The circular photogalvanic effect (CPGE) is observed in InN at inter-band excitation. The function of the CPGE induced current on laser helicity is experimentally demonstrated and illustrated with the microscopic model. A spin-dependent current obtained in InN is one order larger than in the AlGaN/GaN heterostructures at inter-band excitation. The dependence of CPGE current amplitude on light power and incident angle can be well evaluated with phenomenological theory. This sizeable spin-dependent current not only provides an opportunity to realize spin polarized current at room temperature, but also can be utilized as a reliable tool of spin splitting investigation in semiconductors. (c) 2007 Published by Elsevier Ltd.

Effect of inter-level relaxation and cavity length on double-state lasing performance of quantum dot lasers

Double-state lasing phenomena are easily observed in self-assembled quantum dot (QD) lasers. The effect of inter-level relaxation rate and cavity length on the double-state lasing performance of QD lasers is investigated on the basis of a rate equation model. Calculated results show that, for a certain cavity length, the ground state (GS) lasing threshold current increases almost linearly with the inter-level relaxation lifetime. However, as the relaxation rate becomes slower, the ratio of excited state (ES) lasing threshold current over the GS one decreases, showing an evident exponential behavior. A relatively feasible method to estimate the inter-level relaxation lifetime, which is difficult to measure directly, is provided. In addition, fast inter-level relaxation is favorable for the GS single-mode lasing, and leads to lower wetting layer (WL) carrier occupation probability and higher QD GS capture efficiency and external differential quantum efficiency. Besides, the double-state lasing effect strongly depends on the cavity length. (c) 2007 Elsevier B.V. All rights reserved.

Temperature and power-density-dependent inter-shell energy states in InAs/GaAs quantum dots

We have investigated the evolution of exciton state filling in InAs/GaAs quantum dot (QD) structures as a function of the excitation power density by using rnicro-photoluminescence spectroscopy at different temperatures. In addition to the emission bands of exciton recombination corresponding to the atom-like S, P and D, etc. shells of QDs, it was observed that some extra states V between the S and P shells, and D' between the P and D shells appear in the spectra with increasing number of excitons occupying the QDs at a certain temperature. The emergence of these inter-shell excitonic levels is power density and temperature dependent, which is an experimental demonstration of strong exciton-exciton exchange interaction, state hybridization, and coupling of a multi-exciton system in QDs. (c) 2006 Elsevier B.V. All rights reserved.

Temperature and power-density-dependent inter-shell energy states in InAs/GaAs quantum dots

We have investigated the evolution of exciton state filling in InAs/GaAs quantum dot (QD) structures as a function of the excitation power density by using rnicro-photoluminescence spectroscopy at different temperatures. In addition to the emission bands of exciton recombination corresponding to the atom-like S, P and D, etc. shells of QDs, it was observed that some extra states V between the S and P shells, and D' between the P and D shells appear in the spectra with increasing number of excitons occupying the QDs at a certain temperature. The emergence of these inter-shell excitonic levels is power density and temperature dependent, which is an experimental demonstration of strong exciton-exciton exchange interaction, state hybridization, and coupling of a multi-exciton system in QDs. (c) 2006 Elsevier B.V. All rights reserved.

Influence of Inter-Fiber Spacing and Interfacial Adhesion on Failure of Multi-Fiber Model Composites: Experiment and Numerical Analysis

The uniaxial tension experiments on glass-fiber-reinforced epoxy matrix composites reveal that the fragmentations of fibers display vertically aligned fracture, clustered fracture, coordinated fracture, and random fracture with the increase of inter-fiber spacing. The finite element analysis indicates that the fragmentations of fibers displaying different phenomena are due to the stress concentration as well as the inherent randomness of fiber defects, which is the dominant factor. The experimental results show that matrices adjacent to the fiber breakpoints all exhibit birefringent-whitening patterns for the composites with different interfacial adhesion strengths. The larger the extent of the interfacial debonding, the less the domain of the birefringent-whitening patterns. The numerical analysis indicates that the orientation of the matrix adjacent to a fiber breakpoint is caused by the interfacial shear stress, resulting in the birefringent-whitening patterns. The area of shear stress concentrations decides on the domain of the birefringent-whitening patterns.

Assessment of genetic diversities of selected Laminaria (Laminariales, Phaeophyta) gametophytes by inter-simple sequence repeat analysis

Inter-simple sequence repeat (ISSR) analysis was used to assess genetic diversity among 10 pairs of male and female Laminaria gametophytes. A total of 58 amplification loci was obtained from 10 selected ISSR primers, of which 34 revealed polymorphism among the gametophytes. Genetic distances were calculated with the Dice coefficient ranging from 0.006 to 0.223. A dendrogram based on the unweighted pair-group method arithmetic (UPGMA) average showed that most male and female gametophytes of the same species were clustered together and that 10 pairs of gametophytes were divided into four groups. This was generally consistent with the taxonomic categories. The main group consisted of six pairs of gametophytes, which were selected from Laminaria japonica Aresch. by intensive inbreeding through artificial hybridization. One specific marker was cloned, but was not converted successfully into a sequence characterized amplified region (SCAR) marker. Our results demonstrate the feasibility of applying ISSR markers to evaluate Laminaria germplasm diversities.

Inter-simple sequence repeat (ISSR) analysis of genetic variation of Chondrus crispus populations from North Atlantic

ISSR analysis was used to investigate genetic variations of 184 haploid and diploid samples from nine North Atlantic Chondrus crispus Stackhouse populations and one outgroup Yellow Sea Chondrus ocellatus Holmes population. Twenty-two of 50 primers were selected and 163 loci were scored for genetic diversity analysis. Genetic diversity varied among populations, percentage of polymorphic bands (PPB) ranged from 27.0 to 55.8%, H(Nei's genetic diversity) ranged from 0.11 to 0.20 and I(Shannon's information index) ranged from 0.16 to 0.30. Estimators PPB, H and I had similar values in intra-population genetic diversity, regardless of calculation methods. Analysis of molecular variance (AMOVA) apportioned inter-population and intra-population variations for C crispus, showing more genetic variance (56.5%) occurred in intra-population, and 43.5% variation among nine populations. The Mantel test suggested that genetic differentiation between nine C. crispus populations was closely related with geographic distances (R = 0.78, P = 0.002). Results suggest that, on larger distance scale (ca. > 1000 km), ISSR analysis is useful for determining genetic differentiations of C crispus populations including morphologically inseparable haploid and diploid individuals. (c) 2007 Elsevier B.V. All rights reserved.

Transferência de tecnologia: relatório anual 2015.

Arte ou ciência? Transferir, difundir, estender, trocar, intercambiar, compartilhar. Diariamente, essas questões se apresentam como parte das ações do processo de produção, que envolve a ciência e a tecnologia, e a busca de soluções para necessidades, demandas e problemas do dia a dia da pesquisa agropecuária. Estando esta não só envolvida na solução de questões relacionadas ao meio ambiente, aos sistemas de produção, aos arranjos e às cadeias de valor, mas também empenhada em levar respostas às pessoas em seus territórios; de forma que beneficie a agricultores, técnicos da extensão rural e assistência técnica, estudantes e pessoas ligadas à agricultura, e responda as questões que envolvem a produção e a segurança alimentar e nutricional de nossa sociedade. Identificar e conhecer as pessoas, suas necessidades, seus anseios, suas aspirações e desejos requer um elevado grau de sensibilidade e conhecimento. Sensibilidade para perceber e estabelecer diálogo com as pessoas, e conhecimento para que o diálogo permita a troca de saberes. A ciência e os saberes que se manifestam como expressão da cultura orientam novas descobertas e produzem inovação e inclusão. Culturas que expressam a biodiversidade dos biomas e dos agroecossistemas, novos produtos, novos saberes, novos sabores que valorizam os alimentos e a culinária local. Novos saberes permitem redesenhar processos e matrizes, e alcançar novos equilíbrios na permanente busca da sustentabilidade. Arte ou ciência? De fato, buscamos novos métodos e modelagens de trabalho como roteiros alternativos na construção de novos arranjos. Ampliamos nossos meios de interação por caminhos que nos permitam encontrar e definir estratégias inovadoras como forma de promover o desenvolvimento das regiões, dos territórios, dos locais e das pessoas. E mais, trabalhamos permanentemente na busca da transformação dos problemas, por meio de soluções tecnológicas, tendo sempre a preocupação com as pessoas, sua inclusão e qualidade de vida. Assim, movimentamo-nos como que mimetizando nosso DNA ? nossa conhecida dupla hélice em formato helicoidal ascendente ?, caminhando a par e passo na permanente busca por avanços tecnológicos, porém, sem descuidar da inter-relação com as questões sociais. Arte e ciência é, sem dúvida, o que fazemos, com o objetivo de construir uma sociedade harmônica, equilibrada e sustentável. E este Relatório de Transferência de Tecnologia, que ora entregamos, traduz a conexão entre a arte e a ciência que desenvolvemos, por meio de ações aqui apresentadas pelas quarenta e cinco Unidades Descentralizadas da Embrapa, distribuídas em todo o País, e pelo Departamento de Transferência de Tecnologia, no ano de 2015. Um trabalho gratificante, pois proporciona um aprendizado permanente e permite que, a partir da interação com o setor produtivo, cumpramos nossa missão de Viabilizar soluções de pesquisa, desenvolvimento e inovação para a sustentabilidade da agricultura, em benefício da sociedade brasileira.

Construction of Robot Intra-modal and Inter-modal Coordination Skills by Developmental Learning

Q. Meng and M. H. Lee, 'Construction of Robot Intra-modal and Inter-modal Coordination Skills by Developmental Learning', Journal of Intelligent and Robotic Systems, 48(1), pp 97-114, 2007.