3,203 research outputs found

    Genetic and morphometric variation in Schwarziana quadripunctata and Schwarziana mourei (Hymenoptera: Apidae: Meliponini)

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    Schwarziana bees are a ground-nesting stingless bee distributed in the Neotropical region. Schwarziana quadripunctata was the first described and the most studied species of this genus. Now, there are four valid species of Schwarziana bees, but it has been suggested that the diversity of this taxon may be higher, due to undescribed cryptic species. In this study, we investigated the populational diversity of S. quadripunctata using workers collected at 11 localities in Brazil (from the Northeast to South region). We also included one population of S. mourei (collected in São Paulo state, 2 nests). We analysed the bees using geometric morphometrics and molecular analyses amplifying mtDNA cytochrome oxidase I (COI) and 16S to access the diversity among the populations. From the results of geometric morphometrics, the Mahalanobis distances between S. mourei and S. quadripunctata are greater than those distances among S. quadripunctata populations. A similar scenario can also be observed looking to the phylogenetic tree generated by the molecular markers. Morphometry and molecular markers data showed significant association with geographic distance, indicating the existence of intrapopulation variation in S. quadripunctata. Our hypothesis was supported, that the populations of S. quadripunctata showed differences in haplotypic diversity. Overall, these analyses revealed a moderate level of intraspecific variation among S. quadripunctata populations and discriminated well the species S. quadripunctata from S. mourei

    Pathogenicity of two Pratylenchus coffeae populations from Brazil on coffee plants

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    There is limited information on the influence of Pratylenchus coffeae on the growth and development of coffee plants, in spite of the widespread occurrence of this nematode in coffee plantations. In addition, populations of P. coffeae vary in morphological and molecular features, as well as reproductive fitness and pathological potential. The objective of the present study was to compare the pathogenicity of two Brazilian P. coffeae populations, K-5 from Coffea arabica roots and M-2 from Aglaonema sp. roots, in terms of their influence on the plant growth and photosynthesis of Arabian coffee (C. arabica). Five experiments were conducted in controlled conditions, and the results demonstrated that K-5 is pathogenic on coffee, as it can reproduce and causes obvious damage on the plant. Moreover K-5 proved to be very virulent on Arabian coffee, considering its effects on seedling mortality, plant growth and photosynthesis. By contrast, M-2 was considered to be of low virulence, or even non-pathogenic, on coffee because it failed to reproduce. Thus, the results indicate that K-5 and M-2 may be distinct species, supporting the hypothesis of previous authors.9685385

    Computer simulation of simultaneous evolution of individual texture components During recrystallization of an IF steel

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    Computer simulation of simultaneous evolution of individual texture components during recrystallization of an IF steel is carried out. A new methodology has been developed that takes as its starting point experimental data of each texture component evolving during recrystallization. In particular, Magnusson et al. data on IF steel was analyzed in a previous work with the help of the exact analytical tools developed by Rios and Villa for simultaneous transformations. From this analysis parameters such as number of nuclei of each texture component per unit of volume could be obtained and were employed as input for the present computer simulation. From this input 3-d microstructures could then be generated. The methodology proposed here combines experimental data, exact analytical methods and computer simulation and may be employed to extract the maximum information from the experimental data

    Poor sleep quality is associated with cardiac autonomic dysfunction in treated hypertensive men

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    Hypertensives present cardiac autonomic dysfunction. Reduction in sleep quality increases blood pressure (BP) and favors hypertension development. Previous studies suggested a relationship between cardiovascular autonomic dysfunction and sleep quality, but it is unclear whether this association is present in hypertensives. Thus, this study evaluated the relationship between sleep quality and cardiac autonomic modulation in hypertensives. Forty-seven middle-aged hypertensive men under consistent anti-hypertensive treatment were assessed for sleep quality by the Pittsburgh Sleep Quality Index (PSQI—higher score means worse sleep quality). Additionally, their beat-by-beat BP and heart rate (HR) were recorded, and cardiac autonomic modulation was assessed by their variabilities. Mann-Whitney and t tests were used to compare different sleep quality groups: poor (PSQI > 5, n = 24) vs good (PSQI ≤ 5, n = 23), and Spearman’s correlations to investigate associations between sleep quality and autonomic markers. Patients with poor sleep quality presented lower cardiac parasympathetic modulation (HR high-frequency band = 26 ± 13 vs 36 ± 15 nu, P =.03; HR total variance = 951 ± 1373 vs 1608 ± 2272 ms2, P =.05) and cardiac baroreflex sensitivity (4.5 ± 2.3 vs 7.1 ± 3.7 ms/mm Hg, P =.01). Additionally, sleep quality score presented significant positive correlation with HR (r = +0.34, P =.02) and negative correlations with HR high-frequency band (r = −0.34, P =.03), HR total variance (r = −0.35, P =.02), and cardiac baroreflex sensitivity (r = −0.42, P =.01), showing that poor sleep quality is associated with higher HR and lower cardiac parasympathetic modulation and baroreflex sensitivity. In conclusion, in treated hypertensive men, poor sleep quality is associated with cardiac autonomic dysfunction
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