5,414 research outputs found

    Densidade e tamanho de formigueiros de Acromyrmex crassispinus em plantios de Pinus taeda.

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    O objetivo deste trabalho foi avaliar a densidade e o tamanho dos formigueiros de Acromyrmex crassispinus, ao longo do ano, em plantios de Pinus taeda de diferentes idades. Os experimentos foram realizados, em Rio Negrinho e em Três Barras, SC, em talhões de P. taeda com diferentes idades (recém-plantado, três anos e seis anos de idade). Em cada tratamento, foram demarcadas três parcelas de 1 ha. Os formigueiros foram classificados em três classes de tamanho: classe I, até 30 cm de diâmetro; classe II, 31 a 60 cm; e classe III, mais que 61 cm. A densidade de formigueiros de A. crassispinus foi menor no início do desenvolvimento da floresta, praticamente duplicou nos plantios com três anos, e reduziu quando a floresta estava com seis anos. A maior densidade de formigueiros ocorreu no período de dezembro a abril. Os formigueiros aumentaram de tamanho com a idade do pínu

    Carcass Characteristics Of Purebred And Crossbred Nellore Females Fed Solely Pasture

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    This research aimed to compare carcasses of purebred and crossbred Nellore females reared uniquely on pasture (Brachiaria decumbens and Brachiaria brizantha cv. Marandu). Breeds assessed consisted of purebred Nellore (16) and Nellore x Santa Gertrudis crossbred (16), being 32 ± 1.5 months old. All animals were slaughtered as they reached 450 kg. Crossbred females showed higher slaughter, hot and cold carcass weights and longer lengths (P < 0.05). Conversely, purebred animals attained greater carcass yields (P < 0.05). Nonetheless, crossbred females had higher primal cut weights and plate/ flank percentage (P < 0.05). Also, non-carcass components as kidneys, liver, kidney-pelvic-heart fat showed higher weights for crossbred females (P < 0.05). Thus, regarding beef cattle reared and finished exclusively on grazing areas, crossbred females (Nellore x Santa Gertrudis) may be the most profitable ones for cattle raisers, since they produce heavier slaughtering carcasses. Notwithstanding, they might be interesting for meat industry, for yielding more in prime cuts than purebreds, even if raised at the same conditions and slaughtered at same age.3764213422

    Strong disorder renormalization group study of aperiodic quantum Ising chains

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    We employ an adaptation of a strong-disorder renormalization-group technique in order to analyze the ferro-paramagnetic quantum phase transition of Ising chains with aperiodic but deterministic couplings under the action of a transverse field. In the presence of marginal or relevant geometric fluctuations induced by aperiodicity, for which the critical behavior is expected to depart from the Onsager universality class, we derive analytical and asymptotically exact expressions for various critical exponents (including the correlation-length and the magnetization exponents, which are not easily obtainable by other methods), and shed light onto the nature of the ground state structures in the neighborhood of the critical point. The main results obtained by this approach are confirmed by finite-size scaling analyses of numerical calculations based on the free-fermion method

    Distribuição espacial de formigueiros de Acromyrmex crassispinus (Forel) (Hymenoptera: Formicidae) em plantios de Pinus taeda.

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    The spatial distribution of insects is essential to perform control strategies, to improve sample techniques and to estimate economic losses. We aimed to determine the spatial distribution of nests of Acromyrmex crassispinus (Forel) in Pinus taeda plantations. The experiments were carried out in P. taeda plantations with different ages (treatments: recently-planted, three and six-year old plants). The study took place in Rio Negrinho and in Três Barras, SC. Three plots of one hectare were delimited in each treatment, and plots were divided in 64 sample units. The analysis of the dispersion index [variance/mean relationship (I), index of Morisita (I?) and k exponent of negative binomial distribution] showed that the majority of the samplings presented random distribution. Among the three distributions of probabilities studied: Poisson, positive binomial and negative binomial, the Poisson distribution was the best model to fi t the spatial distribution of A. crassispinus nests in all samplings. The result was a random distribution in the plantings of different ages

    Manejo de plantas matrizes de porta-enxerto híbrido de citros.

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    A formação de sementes de citros depende diretamente da polinização, sendo que em alguns casos ocorre a autoincompatibilidade. Nesse trabalho, avaliaram-se práticas de manejo de plantas matrizes de novo porta-enxerto de citros visando maior produção e qualidade de sementes. O experimento iniciou em agosto de 2012 com as plantas matrizes instaladas na área experimental da Embrapa Mandioca e Fruticultura, em Cruz das Almas-BA

    Manejo de plantas matrizes de porta-enxertos híbridos de citros.

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    Os porta-enxertos de citros influenciam mais de 20 caracteristicas hortícolas e fitopatológicas da cultivar copa e seus frutos, e são propagados essencialmente por sementes. As sementes da maioria das variedades cítricas apresentam a característica de poliembrionia, um caráter determinado tanto por fatores genéticos como influenciado por fatores externos abiótico e bióticos
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