838 resultados para Grain Morphology


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We explore the statistical properties of grain boundaries in the vortex polycrystalline phase of type-II superconductors. Treating grain boundaries as arrays of dislocations interacting through linear elasticity, we show that self-interaction of a deformed grain boundary is equivalent to a nonlocal long-range surface tension. This affects the pinning properties of grain boundaries, which are found to be less rough than isolated dislocations. The presence of grain boundaries has an important effect on the transport properties of type-II superconductors as we show by numerical simulations: our results indicate that the critical current is higher for a vortex polycrystal than for a regular vortex lattice. Finally, we discuss the possible role of grain boundaries in vortex lattice melting. Through a phenomenological theory we show that melting can be preceded by an intermediate polycrystalline phase.

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Pig slurry (PS) represents an important nutrient source for plants and using it as fertilizer makes greater nutrient cycling in the environment possible. The aim of this study was to assess how PS application over a period of years can affect grain yield, dry matter production and nutrient accumulation in commercial grain and cover crops. The experiment was carried out in an experimental area of the Universidade Federal de Santa Maria, in Santa Maria, RS, Brazil, from May 2000 to January 2008. In this period, 19 grain and cover crops were grown with PS application before sowing, at rates of 0, 20, 40 and 80 m³ ha-1. The highest PS rate led to an increase in nutrient availability over the years, notably of P, but also of nutrients that are potentially toxic to plants, especially Cu and Zn. The apparent recovery of nutrients by commercial grain and cover crops decreased with the increasing number of PS applications to the soil. Accumulated dry matter production of the crops and maize grain yield were highest at an annual application rate of 80 m³ ha-1 PS. However, common bean yield increased up to 20 m³ ha-1 PS, showing that the crop to be grown should be considered to define the application rate.

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The influence of an inert electrolyte (sodium sulfate) on quasi-two-dimensional copper electrodeposition from a nondeaerated aqueous copper sulfate solution has been analyzed. The different morphologies for a fixed concentration of CuSO4 have been classified in a diagram in terms of the applied potential and the inert electrolyte concentration. The main conclusion is the extension of the well-known Ohmic model for the homogeneous growth regime for copper sulfate solutions with small amounts of sodium sulfate. Moreover, we have observed the formation of fingerlike deposits at large applied potential and inert electrolyte concentration values, before hydrogen evolution becomes the main electrode reaction.

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A diffusion-limited-aggregation (DLA) model with two components (A and B species) is presented to investigate the structure of the composite deposits. The sticking probability PAB (=PBA) between the different species is introduced into the original DLA model. By using computer simulation it is shown that various patterns are produced with varying the sticking probabilities PAB (=PBA) and PAA (= PBB), where PAA (=PBB) is the sticking probability between the same species. Segregated patterns can be analyzed under the condition PAB < PAA, assumed throughout the paper. With decreasing sticking probability PAB, a clustering of the same species occurs. With sufficiently small values of both sticking probabilities PAB and PAA, the deposit becomes dense and the segregated patterns of the composite deposit show a striped structure. The effect of the concentration on the pattern morphology is also shown.

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The authors have developed a live-cell multimodality microscope combining epifluorescence with digital holographic microscopy; it has been implemented with a decoupling procedure allowing to separately measure from the quantitative phase important cell parameters including absolute volume, shape and integral intracellular refractive index. In combination with the numerous different specific fluorescent cellular probes, this multimodality microscopy can address important issues in cell biology. This is demonstrated by the study of intracellular calcium homeostasis associated with the change in cell volume, which play a critical role in the excitotoxicity-induced neuronal death.

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Capsula and seed morphology of W. European species of Euphorbia aggr. flavicoma has been studied. A total of 1500 seeds coming from 13 taxa have been investigated under light microscope, scanning electron microscope and binocular stereoscope. Data were processed by multivariate analysis and the corresponding dendrogram is presented. At de end of the paper, a key is presented allowing to the separation of taxa down to the species level.

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La morfologia de les granes de 28 espècies de Delphinium recollides a Turquia ha estat estudiada per mitjà de la Microscòpia Electrònica de Rastreig (MER). Quatre tipus principals de granes són reportats: subgloboses amb anells continus de lamelles, subpiramidals amb esquames amples o primes, subpiramidals allargades amb esquames i sector-esferoïdals reticulades, que es corresponen amb les seccions reconegudes en els sistemes taxonòmics habituals del gènere, cosa que indica llur bona resolució taxonòmica. Es discuteixen les implicacions biogeogràfiques i sistemàtiques.

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Selostus: Tasoskannerin ja digitaalisen kuva-analyysimenetelmän kalibrointi juurten morfologian kvantifioimiseksi

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Es presenta un estudi morfològic-biomètric de les granes deis taxons del genere Aconitum L. presents a la Península Ibérica. Es tracten aspectes que fan referencia a: 1) disposició de les granes al fol-licle, 2) definido de paramètres (forma general i ornamentado de l'episperma), 3) biometria i 4) descripció de les granes deis représentants ibérics. Els microcaràcters relacionats fonamentalment amb el relleu epispérmic, forma i ornamentado de la base d'inserció (hílum i cél-lules umbil-licals), son els que es mostren mes utils per discriminar els taxons i els que proporcionen mes informado filogenética. Els résultats que s'exposen coincideixen, en línies generals, amb els d'altres autors (SEITZ, 1969; CAPPELETTI & POLDINI, 1984). Es presenten, tanmateix, discrepancies importants pel que fa a la morfología seminal, en especial de l'ornamentació de l'episperma, en les especies A. anthora, A. napellus s.l., A. burnatii i A. vulparia subsp. ranunculifoiium. Es presenta, sovint, polimorfisme seminal en les diferentes poblacions, aïllades geogràficament, d'una mateixa especie o subspècie, tant en el context ibèric com d'Europa central i meridional. Es conclou que aquest polimorfisme és una manifestado mes de la plasticitat fenotípica del genere, particularment intensa en les especies colonitzadores d'àmplia valencia ecológica (A. napellus, s.l.; A. vulparia, s.l.), possiblement conseqiiència de la deriva genética de les poblacions.

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High available aluminium and low levels of calcium below the ploughed zone of the soil are limiting factors for agricultural sustainability in the Brazilian Cerrados (Savannahs). The mineral stresses compound with dry spells effect by preventing deep root growth of cultivated plants and causes yield instability. The mode of inheritance for grain yield and mineral absorption ratio of a diallel cross in soybeans [Glycine max (L.) Merrill] grown in high and low Al areas was identified. Differences among the genotypes for grain yield were more evident in the high Al, by grouping tolerant and non-tolerant genotypes for their respective arrays in the hybrids. A large proportion of genetic variance was additive for grain yield and mineral absorption ratio in both environments. High heritability values suggest that soybeans can be improved by crosses among Al-tolerant genotypes, using modified pedigree, early generation and recurrent selection schemes.

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This fourth volume of Catalan Journal of Linguistics is devoted to a topic discussed at length in the literature but which nevertheless remains a challenge for any view of phonology: the morphology-phonology interaction. The papers collected address two related issues, the role of morphological information in phonology and the role of phonological information in morphology. The first six articles (i.e. McCarthy, Wheeler, Downing, van Oostendorp, José and Auger, and Rice) deal with the former topic; the last three (i.e. Bertinetto and Jetchev, Pérez Saldanya and Vallès, and Viaplana), with the latter. Several papers (Wheeler, van Oostendorp, Rice, Bertinetto and Jetchev, Pérez Saldanya and Vallès, and Viaplana) further discuss the role and concept of paradigms, an old Neogrammarian notion to which renewed attention has been payed both from the phonological perspective (cf. work by Benua 1995, 1997; Burzio 1994 and subsequent work; Kenstowicz 1996, 2002; Steriade 2000, and the articles in the recent volume edited by Downing et al. 2005, among others) and from the morphological perspective (cf. work by Aronoff 1994; Bauer 1997, 2001; Carstairs-McCarthy 1994, 1998; Stump 1991, 1997; van Marle 1985, 1994; Wurzel 1989, and several articles in the recent volume edited by Boucher 2002, among others).

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There is a wide range of evidence to suggest that permeability can be constrained through of induced polarization measurements. For clean sands and sandstones, current mechanistic models of induced polarization predict a relationship between the low-frequency time constant inferred from induced polarization measurements and the grain diameter. A number of observations do, however, disagree with this and indicate that the observed relaxation behavior is rather governed by the so-called dynamic pore radius L. To test this hypothesis, we have developed a set of new scaling relationships, which allow the relaxation time to be computed from the pore size and the permeability to be computed from both the Cole-Cole time constant and the formation factor. Moreover, these new scaling relationships can be also used to predict the dependence of the Cole-Cole time constant as a function of the water saturation under unsaturated conditions. Comparative tests of the proposed new relationships with regard to various published experimental results for saturated clean sands and sandstones as well as for partially saturated clean sandstones, do indeed confirm that the dynamic pore radius L is a much more reliable indicator of the observed relaxation behavior than grain-size-based models.

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Whole-grain foods are touted for multiple health benefits, including enhancing insulin sensitivity and reducing type 2 diabetes risk. Recent genome-wide association studies (GWAS) have identified several single nucleotide polymorphisms (SNPs) associated with fasting glucose and insulin concentrations in individuals free of diabetes. We tested the hypothesis that whole-grain food intake and genetic variation interact to influence concentrations of fasting glucose and insulin. Via meta-analysis of data from 14 cohorts comprising ∼ 48,000 participants of European descent, we studied interactions of whole-grain intake with loci previously associated in GWAS with fasting glucose (16 loci) and/or insulin (2 loci) concentrations. For tests of interaction, we considered a P value <0.0028 (0.05 of 18 tests) as statistically significant. Greater whole-grain food intake was associated with lower fasting glucose and insulin concentrations independent of demographics, other dietary and lifestyle factors, and BMI (β [95% CI] per 1-serving-greater whole-grain intake: -0.009 mmol/l glucose [-0.013 to -0.005], P < 0.0001 and -0.011 pmol/l [ln] insulin [-0.015 to -0.007], P = 0.0003). No interactions met our multiple testing-adjusted statistical significance threshold. The strongest SNP interaction with whole-grain intake was rs780094 (GCKR) for fasting insulin (P = 0.006), where greater whole-grain intake was associated with a smaller reduction in fasting insulin concentrations in those with the insulin-raising allele. Our results support the favorable association of whole-grain intake with fasting glucose and insulin and suggest a potential interaction between variation in GCKR and whole-grain intake in influencing fasting insulin concentrations.

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Selostus: Aluskasveja voi käyttää toistuvasti viljan viljelyssä

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The interest in reducing maize row spacing in the short growing season regions of Brazil is increasing due to potential advantages such as higher radiation use efficiency. This experiment was conducted to evaluate the effect of row spacing reduction on grain yield of different maize cultivars planted at different dates. The trial was conducted in Lages, in the State of Santa Catarina, Brazil, during 1996/97 and 1997/98 growing seasons, in a split-split plot design. Early (October 1st) and normal (November 15) planting dates were tested in the main plot; two morphologically contrasting cultivars (an early single-cross and a late double-cross hybrids) were evaluated in the split plots and three row widths (100, 75 and 50 cm) were studied in the split-split plots. The reduction of row spacing from 100 to 50 cm increased linearly maize grain yield. The yield edge provided by narrow rows was higher when maize was sown earlier in the season. Differences in hybrid cycle and plant architecture did not alter maize response to the reduction of row spacing.