17 resultados para gravimetric inversion
em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Cytogenetic investigations based on conventional and differential staining analysis (C-and replication R-banding and Ag-staining) were carried out on eight specimens of Phyllopezus periosus, 17 of P. pollicaris pollicaris, and one of P. pollicaris przewalskii collected from different localities of Brazil. P. periosus and P. p. pollicaris share the same diploid number of 2n = 40 chromosomes, and their karyotypes are very distinctive regarding to the number of biarmed and uniarmed chromosomes. After careful side-by-side comparison of R-banded chromosomes in both taxa, pronounced homology between, at least, eight pairs was revealed. The R-banding patterns allowed us to postulate that karyotype differentiation could be due to pericentric inversion events. P. p. przewalskii (2n = 38) exhibited a very similar karyotype to that found in P. p. pollicaris, except for the presence of one metacentric pair, which probably resulted from a Robertsonian rearrangement. Single and multiple pairs of NOR-bearing chromosomes, showing variation in number and location, were detected among the three forms of Phyllopezus. Similar C-banding patterns were found in P. periosus and P. p. pollicaris. Sex chromosomes were not positively identified.
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The karyotype of a new species of Paratelmatobius from the P cardosoi group is described. As with other Paratelmatobius and Scythrophrys karyotypes, Paratelmatobius sp. (aff. cardosoi) shows a diploid number of 24 chromosomes, in addition to other similarities with the former karyotypes. The Paratelmatobius sp. (aff. cardosoi) karyotype differs from that of P. cardosoi in the morphology of pair 4, the NOR location and the C-bands in pairs 3 and 8 (exclusive to Paratelmatobius sp.) and those of pairs 7 and 9 (exclusive to P. cardosoi). Both karyotypes also differ in the amount of heterochromatin in pair 1. The presence of interstitial heterochromatin in the long arm of pair 1 and the interstitial C-bands in both arms of chromosome 5 are apparently synapomorphic characters of P. cardosoi and Paratelmatobius sp. (aff. cardosoi), since they are absent in the other Paratelmatobius and Scythrophrys karyotypes. In Paratelmatobius sp. (aff. cardosoi), the nucleolus organizer region is on the short arm of a small metacentric chromosome (pair 9), an arrangement similar to the NOR-bearing chromosome pair in the karyotype of P. poecilogaster and in karyotype 11 of Scythrophrys. A conspicuous heteromorphism unrelated to the sex determining mechanism was also observed and probably arose from a pericentric inversion.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Avaliou-se o método de determinação gravimétrica da matéria orgânica do solo pela perda de massa por incineração a 300ºC e comparou-se com o carbono determinado pelo método Walkley-Black. Os dois métodos foram correlacionados positivamente com a seguinte equação de regressão linear: y = 3,720x + 0,2914. r = 0,937. O coeficiente. 3,720 foi maior do que os encontrados na literatura. que variaram de 1,68 a 2,13. Esta diferença foi atribuída ao maior grau de oxidação da matéria orgânica dos solos das regiões tropicais. O método de incineração é aplicável para determinação do C do solo em rotina. O método não contamina o meio ambiente com metal tóxico (Cr6+) e não oferece riscos aos analistas com o uso de ácido sulfúrico concentrado.
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Drosophila sturtevanti (37 strains) showed eighteen inversions, five new and thirteen previously described. Among these strains, 24 were maintained for seven to 21 years under laboratory conditions, eight for less than 1 year, and six were natural samples analysed in the first generation after collection. Flies from natural samples were the most polymorphic in the number of different inversions as well as in the frequency of flies bearing heterozygous inversions. In all cases, chromosome III presented the greatest number of inversions, and most of them occurred in strains from the Amazonian region. The data obtained were consistent with the hypothesis that the inversion variability of a species is proportional to the variability of its habitats.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Cytogenetic studies conduced on a sample of 19 specimens of rainbow trout (Oncorhyncus mykiss) showed that 6 presented two chromosomes with a single subterminal AgNOR on the short arms and 13 presented one chromosome with a single subterminal Ag-NOR and a second chromosome with two small subterminal Ag-NORs. Synaptonemal complex studies showed the presence of a pairing failure involving the two lateral elements (LEs) of the NOR-bearing chromosomes only in those specimens with two different NOR-bearing chromosomes, suggesting that the chromosomes with two Ag-NORs originated from a paracentric inversion involving a terminal segment of the original NOR-bearing chromosome. A comparative analysis between three normal and three heterozygous fishes suggest that in the latter group the LEs of the NOR-bearing chromosomes initiate the synaptic process in a more delayed manner, the synapsis develops more quickly, and the nucleolus stays associated with chromosomes for a longer time.
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The population inversion of the Tm3+ in GLKZ glass involved in the 1470 nm emission (3H4 → 3F 4) as a function of Tb (or Eu) concentration was calculated by computational simulation for a CW laser pumping at 792 nm. These calculations were performed using the experimental Tm→Tb an Tm→Eu transfer rates and the spectroscopic parameters of the Tm (0.1 mol %) system. The result shows that 0.2 mol % (Tb3+) and 0.4 mol % of Eu3+ ions propitiate best population inversion of Tm3+ (0.1 mol %) maximizing the amplification coefficient of germanate (GLKZ) glass when operating as laser intensity amplification at 1470 nm. Besides the effective deactivation of the 3F4 level, the presence of Tb3+ or Eu 3+ ions introduce a depopulation of the 3H4 emitting level by means of a cross relaxation process with Tm3+ ions. In spite of this, the whole effect is verified to be benefic for using Tm-doped GLKZ glass codoped with Tb3+ or Eu3+ as a suitable material for confectioning optical amplifiers that operates in the S-band for telecommunication.
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Twenty-two 14C datings were performed at the central sector of the Paraná coast to define Holocene regressive barrier evolution. The barrier Pleistocene substratum was ascribed an age between 40 400 and 30 000 yr BP, but it can also represent the penultimate sea level highstand during marine isotope stage 5e. The Holocene barrier samples provided ages between 8542-8279 and 2987-2751 cal yr BP, and showed at least six age inversions that were related to age differences between in situ or low-distance transported shells or trunk fragments, and high-distance transported vegetal debris, wood fragments and organic matter samples. The regressive Holocene barrier age was 4402-4135 cal yr BP near the base, and 2987-2751 cal yr BP near the top. Most of the vegetal remains were transported by ebb tidal currents from the estuaries to the inner shelf below wave base level during the mid-Holocene highstand; they were transported onshore by storm waves and littoral currents during the sea level lowering after the sea level maximum, and were deposited mainly as middle shoreface swaley cross-stratification facies. © 2008.
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This paper presents the results of thermogravimetric analysis (TGA) tests in PVC (1.0; 2.0 mm) and HDPE (0.8; 2.5 mm) geomembranes exposed to weathering and leachate after 30 months. The aim of this paper is the comparison of fresh and exposed samples to assess the degradation process concerning the total loss of mass of geomembranes. The exposure was conducted in accordance with the recommendations of ASTM standards. The TGA tests were carried out according to ASTM D6370 and E2105. Results show, for instance, that for PVC geomembrane the largest reductions of plasticizers occurred for samples exposed to weathering. The loss of plasticizers after the exposure contributed to the decrease of deformation and consequent increase in stiffness. TGA tests shows to be a valuable tool to control the quality of the materials. © 2012 ejge.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)