937 resultados para Elements


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The consequences of the use of embedded crack finite elements with uniform discontinuity modes (opening and sliding) to simulate crack propagation in concrete are investigated. It is shown the circumstances in which the consideration of uniform discontinuity modes is not suitable to accurately model the kinematics induced by the crack and must be avoided. It is also proposed a technique to embed cracks with non-uniform discontinuity modes into standard displacement-based finite elements to overcome the shortcomings of the uniform discontinuity modes approach.

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An on-line dialysis flow system coupled to inductively coupled plasma mass spectrometry to determine trace elements in serum samples by isotope dilution is presented. Isotope dilution was performed on samples incubated with enriched Cu-65, Zn-66, Se-77 and Pb-206 for 24 h at 36degreesC prior to dialysis to quantified total element concentrations. The sample and acceptor solutions flowed through the dialysis unit with cellophane membrane placed in between the compartments. The serum sample (1 mL) was left to recycle in a closed path while the acceptor solution was continuously pumped along the dialyzer channel and through a cationic AG50W X-8 resin column. After 10 min, around 70% of Na, K and Cl migrate from the sample. Three replicate injections of 0.1 mL were performed for the clean sample after each separation step. The on-line coupling of the dialyzer to ICP-MS allowed isotope dilution for total element determination either in the cleaned sample or by eluting the cations retained in the resin to be carried out. Results demonstrated no matrix effects from alkaline elements or spectral interference from ArNa+ on Cu-63, ArCl+ on Se-77 and (SO2+)-S-34 on Zn-66. The precision of isotope ratio measurements for Cu and Zn was around 1% and for Se and Pb was around 2.5%. The values found for the reference serum sample IMEP-17 were in good agreement with the certified values for Cu, Zn and Se.

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Transposable elements are major components of plant genomes and they influence their evolution, acting as recombination hot spots, acquiring specific cell functions or becoming part of protein-coding regions. The latter is the subject of the present analysis. This study is a report on the annotation of transposable elements (TEs) in expressed sequences of Coffea arabica, Coffea canephora and Coffea racemosa, showing the occurrence of 383 ESTs and 142 unigenes with TE fragments in these three Coffea species. Based on selected unigenes, it was possible to suggest 26 putative proteins with TE-cassette insertions, demonstrating a likely contribution to protein variability. The genes for two of those proteins, the fertility restorer (FR) and the pyrophosphate-dependent phosphofructokinase (PPi-PFKs) genes, were selected for evaluating the impact of TE-cassettes on host gene evolution of other plant genomes (Arabidopsis thaliana, Oryza sativa and populus trichocarpa). This survey allowed identifying a FR gene in O. sativa harboring multiple insertions of LTR retrotransposons that originated new exons, which however does not necessarily mean a case of molecular domestication. A possible transduction event of a fragment of the PPi-PFK beta-subunit gene mediated by Helitron ATREPX1 in Arabidopsis thaliana was also highlighted.

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Horizontal transfer ( HT), defined as the transfer of genetic material between species, is considered to be an essential step in the 'life cycle' of transposable elements. We present a broad overview of suspected cases of HT of transposable elements in Drosophila. Hundred-one putative events of HT have been proposed in Drosophila for 21 different elements (5.0% refer to non-long terminal repeat (LTR) retrotransposons, 42.6% to LTR retrotransposons and 52.4% to DNA transposons). We discuss the methods used to infer HT, their limits and the putative vectors of transposable elements. We outline all the alternative hypotheses and ask how we can be almost certain that phylogenetic inconsistencies are due to HT.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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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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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Transitional cell carcinoma (TCC) of the bladder is a neoplasm with variability in its clinical behavior. Although there are several studies correlating stage and ABO isoantigen expression with invasiveness, there is no single predictor factor to assess the potential invasiveness, especially in the low grade, non-invasive TCC. In the present study we evaluated the correlation of histological grade plus stage and the expression of beta human chorionic gonadotropin (beta-hCG), in 100 cases of TCC, with the clinical behavior. These features were correlated with tumor progression in patients with at least two years of follow up. We observed more aggressiveness in G4 group (high grade and invasive) (93% had tumor progression) when compared to G1 group (low grade and superficial) (11% had tumor progression). However in 25.5% of the TCC cases (groups G2: low grade and invasive and G3: high grade and superficial) the clinical behavior was intermediate, showing some limitation in using grading and staging only, as a predictive factor. There was an expression of beta-hCG in 21.4% of the cases in up to 25% of the tumor cells without any trophoblastic morphology. These beta-hCG producing TCC had a strong correlation with aggressiveness: 39.1% and 12.8% of the TCC expressed beta-hCG with and without tumor progression, respectively.

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Final-state qq̄ interactions give origin to nonzero values of the off-diagonal element ρ1,-1 of the helicity density matrix of vector mesons produced in e+e- annihilations, as has been confirmed by recent OPAL data on φ, D*, and K*. New predictions are given for ρ1,-1 of several mesons produced at large XE and small pT - i.e., collinear with the parent jet - in the annihilation of polarized e+ and e-; the results depend strongly on the elementary dynamics and allow further nontrivial tests of the standard model.

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Randomly amplified polymorphic DNA (RAPD) analysis of 35 Paracoccidioides brasiliensis isolates was carried out to evaluate the correlation of RAPD profiles with the virulence degree or the type of the clinical manifestations of human paracoccidioidomycosis. The dendrogram presented two main groups sharing 64% genetic similarity. Group A included two isolates from patients with chronic paracoccidioidomycosis; group B comprised the following isolates showing 65% similarity: two non-virulent, six attenuated, five virulent, eight from patients with chronic paracoccidioidomycosis and two from patients with acute paracoccidioidomycosis. The virulent Pb18 isolate and six attenuated or non-virulent samples derived from it were genetically indistinguishable (100% of similarity). Thus, in our study, RAPD patterns could not discriminate among 35 P. brasiliensis isolates according to their differences either in the degree of virulence or in the type of the clinical manifestation of this fungal infection. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

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In the present study, we describe the cloning and characterization of a new SINE-like element from O. niloticus (ROn-2) and show the distribution of this SINE and a previously isolated SINE, ROn-1, in the chromosomes of O. niloticus. The ROn-2 element is 359 base pairs (bp) in length, contains short direct terminal repeats, a tRNA-related region similar to tRNA Val and tRNA Arg, a tRNA-unrelated region, and a poly-A tail. Analysis of the chromosomal distribution of ROn-1 and ROn-2 by fluorescent in situ hybridization showed that both SINE sequences are present in all chromosomes of tilapia, and organized in small clusters. The only exception was a large cluster of ROn-1 repeats found in the middle of the long arm of chromosome 1. In view of our data we discuss the hypothesis that the absence of large clusters of SINE sequences and the structural composition of these sequences may explain the absence of base-specific fluorochrome bands in the chromosomes of tilapia.

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Up to now, investigations of expression and regulation of P transposable element have been almost exclusively carried out with the Drosophila melanogaster canonical P element. Analyzing eight species of the saltans group, we detected transposase mRNA in germline tissues of D. saltans and D. prosaltans and repressor mRNA in somatic tissues of D. saltans and D. sturtevanti. Sequencing analysis suggested that these transcripts might belong to the canonical subfamily and that they can be transpositionally active only in D. saltans. dN and dS values of Adh and the P element suggested that the sequences found in D. saltans and D. prosaltans might have been present in the ancestor of the saltans subgroup and that the sequence found in D. sturtevanti might have been horizontally transferred from D. saltans.

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This paper adresses the problem on processing biological data such as cardiac beats, audio and ultrasonic range, calculating wavelet coefficients in real time, with processor clock running at frequency of present ASIC's and FPGA. The Paralell Filter Architecture for DWT has been improved, calculating wavelet coefficients in real time with hardware reduced to 60%. The new architecture, which also processes IDWT, is implemented with the Radix-2 or the Booth-Wallace Constant multipliers. Including series memory register banks, one integrated circuit Signal Analyzer, ultrasonic range, is presented.