Regeneração e multiplicação de germoplasma de milho (Zea mays L.) na Região Amazônica.

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Avaliação do estado nutricional de espécies componentes de sistema agroflorestais em solos de baixa fertilidade em Rondônia.

Este trabalho tem como objetivo avaliar o estado nutricional de espécies componentes de sistemas agroflorestais estabelecidos em solos de baixa fertilidade no Estado de Rondônia

Germinação in vitro de grãos de pólen de Vriesea spp. (Bromeliaceae).

Estudos de viabilidade polínica são fundamentais como suporte ao melhoramento genético de bromeliáceas e para tal o ajuste de meios de germinação de pólen é determinante. Este trabalho objetivou avaliar a germinação de grãos de pólen in vitro e o subsequente crescimento do tubo polínico em Vriesea carinata, V. friburgensis, V. michaelii, V. paraibica e V. simplex. Grãos de pólen coletados na antese foram inoculados em quatro meios de cultura: BM, BKM, MBKM e SM, solidificados com agar (0,8%); pH ajustado a 6,5 e mantidos a uma temperatura de 27 ± 1 ºC. O delineamento experimental foi inteiramente casualizado em esquema fatorial 5 x 4 (genótipo x meios de cultura), com 12 repetições, avaliando-se 300 grãos de pólen quanto à viabilidade e o comprimento de 25 tubos polínicos, aleatoriamente, por tratamento. Após 8 horas em cultura, verificou-se que os meios BKM e SM resultaram em maior germinação e comprimento do tubo polínico. Para as espécies V. carinata (80,33 %), V. paraibica (88,73 %), V. simplex (90,46 %) e V. michaelii (90,03 %) o melhor meio de cultura foi SM e para V. friburgensis, BKM (90,43 %) foi o melhor

Orbital magnetism in axially deformed sodium clusters: From scissors mode to dia-para magnetic anisotropy

Low-energy orbital magnetic dipole excitations, known as scissors mode (SM), are studied in alkali metal clusters. Subsequent dynamic and static effects are explored. The treatment is based on a self-consistent microscopic approach using the jellium approximation for the ionic background and the Kohn-Sham mean field for the electrons. The microscopic origin of SM and its main features (structure of the mode in light and medium clusters, separation into low- and high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole plasmons, contributions of shape isomers, etc) are discussed. The scissors M1 strength acquires large values with increasing cluster size. The mode is responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum shell effects induce a fragile interplay between Langevin diamagnetism and van Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic susceptibility of particular light clusters. Finally, several routes for observing the SM experimentally are discussed.Comment: 21 pages, 7 figure

Estimating physical properties from liquid crystal textures via machine learning and complexity-entropy methods

Imaging techniques are essential tools for inquiring a number of properties from different materials. Liquid crystals are often investigated via optical and image processing methods. In spite of that, considerably less attention has been paid to the problem of extracting physical properties of liquid crystals directly from textures images of these materials. Here we present an approach that combines two physics-inspired image quantifiers (permutation entropy and statistical complexity) with machine learning techniques for extracting physical properties of nematic and cholesteric liquid crystals directly from their textures images. We demonstrate the usefulness and accuracy of our approach in a series of applications involving simulated and experimental textures, in which physical properties of these materials (namely: average order parameter, sample temperature, and cholesteric pitch length) are predicted with significant precision. Finally, we believe our approach can be useful in more complex liquid crystal experiments as well as for probing physical properties of other materials that are investigated via imaging techniques.Comment: 11 two-column pages, 7 figures; accepted for publication in Physical Review

Produção de mudas de cupuaçu.

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Classificação física de farinhas oriundas do Estado do Acre/Brasil.

O objetivo deste trabalho foi caracterizar farinhas de mandioca produzidas na regional do Juruá/Acre, esperando com isso fornecer informações sobre composição nutricional e características do produto. Foram analisadas 18 amostras de farinhas comerciais de mandioca com diferentes procedências, quanto à granulometria e colorimetria. As farinhas de mandioca analisadas pertencem ao grupo seca, subgrupos, bijusada e grossa, classe, amarela e tipo 1 e por apresentaram valores de reflectância do croma b* tendendo ao amarelo, com elevado valor médio de luminosidade L* na ordem de 80 reflectância, pertencem à classe de farinha de cor amarela

Essential oil content and chemical composition of Lippia gracilis Schauer cultived in the Sub-meddle São Francisco Valley.

Lippia gracilis is a native species of the Caatinga, whose leaves have significant potential for economic use by chemical and pharmaceutical industries due to the presence of thymol and carvacrol. Considering the lack of agronomic data for the species, especially for semi-arid conditions where it is possible to find natural populations, the aim of this work was to assess the effects of drought and different doses of organic fertilization in biomass production and content, yield and chemical composition of the essential oil. The experiment was conducted with 16 treatments that consisted of presence and absence of organic fertilizer, mineral fertilizer and irrigation. The analyzed variables after 120 days of culture were: total length until the last leaf, fresh weight of aerial parts with stem, leaf dry weight a nd fresh weight, content and chemical composition of essential oil, and moisture. In the conditions where this st udy was conducted, it was observed that the organic and mineral fertilization and irrigation positively inf luenced the production of biomass and essential oil content. However, cultivation methods did not significantly affect the chemical composition of essential oils, which shows the hardiness of the species to changes in availability of water and nutrients