185 resultados para zeros of Gram polynomials


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Natural products have been studied aiming to understand their biological properties. Thus, this study aimed to investigate the antimicrobial activity of twenty-seven essential oils (EOs) used in aromatherapy procedures, a natural therapy with great emphasis currently used against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa strains. The agar dilution method was carried out and minimal inhibitory concentration against 50% and 90% of strains (MIC50% and MIC90% values) were reported. The S.aureus strains were highly susceptible with MIC90% from 0.21mg/mL to black pepper (Piper nigrum) and tea tree (Melaleuca alternifolia) to 26.52mg/mL with copaiba (Copaifera officinalis) EO. Cinnamon (Cinnamomum cassia) and clove (Syzygium aromaticum) EOs were effective against E.coli (2.0mg/mL) while the S.aromaticum EO was against P.aeruginosa (8.29mg/mL). Thus, the higher susceptibility of Gram-positive bacteria when compared with Gram-negative strains was found, and a large variability in the potential antibacterial has also been observed.

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In this paper, we present a new construction and decoding of BCH codes over certain rings. Thus, for a nonnegative integer t, let A0 ⊂ A1 ⊂···⊂ At−1 ⊂ At be a chain of unitary commutative rings, where each Ai is constructed by the direct product of appropriate Galois rings, and its projection to the fields is K0 ⊂ K1 ⊂···⊂ Kt−1 ⊂ Kt (another chain of unitary commutative rings), where each Ki is made by the direct product of corresponding residue fields of given Galois rings. Also, A∗ i and K∗ i are the groups of units of Ai and Ki, respectively. This correspondence presents a construction technique of generator polynomials of the sequence of Bose, Chaudhuri, and Hocquenghem (BCH) codes possessing entries from A∗ i and K∗ i for each i, where 0 ≤ i ≤ t. By the construction of BCH codes, we are confined to get the best code rate and error correction capability; however, the proposed contribution offers a choice to opt a worthy BCH code concerning code rate and error correction capability. In the second phase, we extend the modified Berlekamp-Massey algorithm for the above chains of unitary commutative local rings in such a way that the error will be corrected of the sequences of codewords from the sequences of BCH codes at once. This process is not much different than the original one, but it deals a sequence of codewords from the sequence of codes over the chain of Galois rings.

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

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The presence of yeasts and bacteria was studied in 26 patients with denture stomatites, and the results compared with the data of the normal mucosa foi edentoulous patients, who used or not upper dentures. The use of dentures caused an increase in the amount of yeasts, and there was a correlation with the severity of the stomatitis. Gram positives cocci and bacilus predominated in all studied groups, but in cases of stomatitis there was an increase in the amount of Gram negative cocci and filamentous. These results suggest that besides yeasts, modifications of the bacteria flora can be relevant for the development of denture stomatitis.

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

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

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Peritoneal dialysis has a high acceptance rate in Latin America, thus the knowledge concerning complication patterns is of great relevance. This work reviews Latin American data on peritonitis, the most serious complication of peritoneal dialysis.The incidence of peritonitis has been reduced over time, concomitantly with the incorporation of safer exchange systems and the use of prophylactic measurements. Today, rates tower than 1 episode per 24 patient-months are commonly reported. Furthermore, changes in causative organisms have been observed, with predominance of Staphylococcus aureus up through the mid-1990s, as welt as increases in coagulase-negative staphylococcus and participation of gram negatives. However, the prevalence of S. aureus is still high, due possibly to climatic conditions and the elevated prevalence of carriers. Resolution rate varies from 55% to 78%, transfer to hemodialysis from 10.9% to 15.4%, and death in 3% to 9.9% of cases. Outcome is worse in S. aureus episodes compared to those with coagulase-negative staphylococcus, despite the higher percentage of oxacillin-resistant strains among the former. In general, despite socioeconomic or climatic conditions, our results are similar to those in developed countries, perhaps as a consequence of technological improvements and/or center expertise.

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The behavior of microorganisms towards the antibiotic action of propolis has been widely investigated. Since reports dealing with seasonal effect on propolis activity are not available, this assay was carried out aiming to observe the in vitro antimicrobial activity of propolis, collected during the four seasons, on bacterial strains isolated from human infections. Dilution of ethanolic extract of propolis (EEP) in agar was the method performed, with serial concentrations ranging from 0.4 to 14.0% (% v/v). The behavior of some bacteria was analysed according to the incubation period in medium plus propolis, and the survival curve was plotted. It was verified that the growth of Gram-positive bacteria is inhibited by low propolis concentrations (0.4%) whereas Gram-negative bacteria were less susceptible to this substance, the minimal inhibitory concentration ranging from 4.5 to 8.0%. There was no significant difference with regards to the seasonal effect on the survival curve of Staphylococcus aureus and Escherichia coli; after incubation with propolis, there was an efficient antimicrobial action, mainly towards Gram-positive bacteria. (C) 2000 Elsevier B.V. Ireland Ltd. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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In this paper, we consider a class of strong symmetric distributions, which we refer to as the strong c-symmetric distributions. We provide, as the main result of this paper, conditions satisfied by the recurrence relations of certain polynomials associated with these distributions.

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Two applications of the modified Chebyshev algorithm are considered. The first application deals with the generation of orthogonal polynomials associated with a weight function having singularities on or near the end points of the interval of orthogonality. The other application involves the generation of real Szego polynomials.