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Showing papers by "Universidade Federal de Santa Catarina published in 1998"


Journal ArticleDOI
TL;DR: The optimized δ-expansion is a nonperturbative approach for field theoretic models which combines the techniques of perturbation theory and the variational principle as mentioned in this paper.
Abstract: The optimized δ-expansion is a nonperturbative approach for field theoretic models which combines the techniques of perturbation theory and the variational principle This technique is discussed in the λφ4 model and then implemented in the Walecka model for the equation of state of nuclear matter The results obtained with the δ expansion are compared with those obtained with the traditional mean field, relativistic Hartree and Hartree-Fock approximations

672 citations


Journal ArticleDOI
TL;DR: Together this data strongly supports the view that the plants belonging to the genus Phyllanthus have potential beneficial therapeutic actions in the management of hepatitis B, nefrolitiase, and in painful disorders.
Abstract: The plants of the genus Phyllanthus (Euphorbiaceae) are widely distributed in most tropical and subtropical countries, and have long been used in folk medicine to treat kidney and urinary bladder disturbances, intestinal infections, diabetes, and hepatitis B. In recent years, the interest in the plants has increased considerably. Substantial progress on their chemistal and pharmacological properties, as well as a few clinical studies of some Phyllanthus species have been made. This review discusses the current knowledge of their chemistry, the in vitro and in vivo pharmacological, biochemical, and clinical studies carried out on the extracts, and the main active constituents isolated from different species of plants of the genus Phyllanthus. These studies carried out with the extracts and purified compounds from these plants support most of their reported uses in folk medicine as an antiviral, in the treatment of genitourinary disorders, and as antinociceptive agents. However, well-controlled, double-binding clinical trials are lacking. Several compounds including alkaloids, flavonoids, lignans, phenols, and terpenes were isolated from these plants and some of them interact with most key enzymes. Together this data strongly supports the view that the plants belonging to the genus Phyllanthus have potential beneficial therapeutic actions in the management of hepatitis B, nefrolitiase, and in painful disorders.

495 citations


Journal ArticleDOI
TL;DR: A physically based model for the metal-oxide-semiconductor (MOS) transistor suitable for analysis and design of analog integrated circuits is presented.
Abstract: This paper presents a physically based model for the metal-oxide-semiconductor (MOS) transistor suitable for analysis and design of analog integrated circuits. Static and dynamic characteristics of the MOS field-effect transistor are accurately described by single-piece functions of two saturation currents in all regions of operation. Simple expressions for the transconductance-to-current ratio, the drain-to-source saturation voltage, and the cutoff frequency in terms of the inversion level are given. The design of a common-source amplifier illustrates the application of the proposed model.

314 citations


Journal ArticleDOI
TL;DR: In this paper, the authors discuss some experimental procedures which may be employed for isolation of active compounds from medicinal plants based on their experience, and emphasize some insights about the way to obtain more active and selective compounds from natural products through structural modifications oriented for analysis of structure-activity relationships.
Abstract: In the present paper we discuss, based in our experience, some experimental procedures which may be employed for isolation of active compounds from medicinal plants. We have also emphasized some insights about the way to obtain more active and selective compounds from natural products through structural modifications oriented for analysis of structure-activity relationships.

285 citations


Journal ArticleDOI
01 Jan 1998
TL;DR: In this paper, an inverse semigroup S(G) associated to a group G is constructed, in a canonical way, and the actions of S (G) are shown to be in one-to-one correspondence with the partial actions of G, both in the case of actions on a set, and that of actions as operators on a Hilbert space.
Abstract: Given a group G, we construct, in a canonical way, an inverse semigroup S(G) associated to G. The actions of S(G) are shown to be in one-to-one correspondence with the partial actions of G, both in the case of actions on a set, and that of actions as operators on a Hilbert space. In other words, G and S(G) have the same representation theory. We show that S(G) governs the subsemigroup of all closed linear subspaces of a G-graded C*-algebra, generated by the grading subspaces. In the special case of finite groups, the maximum number of such subspaces is computed. A "partial" version of the group C*-algebra of a discrete group is introduced. While the usual group C*-algebra of finite commutative groups forgets everything but the order of the group, we show that the partial group C*-algebra of the two commutative groups of order four, namely Z/4Z and Z/2Z ED Z/2Z, are not isomorphic.

235 citations


Journal ArticleDOI
TL;DR: In this article, the effect of ethanol on microbial degradation of representative BTX compounds under electron acceptor conditions commonly found in intrinsic bioremediation projects was investigated. But, little is known about ethanol's effect on biOREmediation of the toxic BTX contaminants.

179 citations


Journal ArticleDOI
TL;DR: The use of molecular markers tightly linked to resistance genes to facilitate the identification of an uncharacterized resistance gene for which no discriminating race of the pathogen is known is described.
Abstract: Two independently assorting dominant genes conditioning resistance to bean anthracnose were identified in an F2 population derived from the highly resistant bean differential cultivar, ‘G 2333’. One gene was allelic to the Co-4 gene in the differential cultivar ‘TO’ and was named Co-4 2 , whereas the second gene was assigned the temporary name Co-7 until a complete characterization with other known resistance genes can be conducted. Two RAPD markers linked to the Co-4 2 allele were identified. One RAPD, OAS13950, co-segregated with no recombinants in two segregating populations of 143 F2 individuals, whereas the second RAPD, OAL9740, mapped at 3.9 cM from the Co-4 2 allele. Two 24-mer SCAR primers (SAS13), developed from the OAS13950 RAPD marker, were dominant and polymorphic, similar to the original RAPD, and supported the tight linkage between the marker(s) and the Co-4 2 allele. The markers were present in germplasm with known resistance alleles at the Co-4 locus. The presence of the markers in two other differential cultivars not previously characterized and in four navy bean cultivars suggests the existence of a gene family for anthracnose resistance at or near the Co-4 locus. Since the Co-7 gene was present only in germplasm which also possessed the Co-4 2 and Co-5 genes, the SAS13 markers were used in combination with standard inoculation techniques to identify F3 lines in which the Co-7 gene was homozygous and the Co-4 2 allele was absent. A similar strategy of marker-assisted dissection is proposed to identify resistant lines in which the Co-5 gene is absent and the Co-7 gene is present by selecting against the OAB3450 marker, which has been shown previously to be linked to the Co-5 gene. These genes cannot be distinguished using traditional screening methods since all current races of the pathogen virulent to the Co-5 gene are avirulent to the Co-4 2 and Co-7 genes. We describe the use of molecular markers tightly linked to resistance genes to facilitate the identification of an uncharacterized resistance gene for which no discriminating race of the pathogen is known.

176 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the oxidative susceptibility of plasma obtained from rats after intragastric administration of quercetin to know whether or not it acts as an in vivo antioxidant after metabolic conversion.

171 citations


Journal ArticleDOI
TL;DR: In this article, the adsorption of the anionic dyes orange IV, orange G and xylenol orange on chitin was studied, employing the Langmuir isotherm.
Abstract: The adsorption of the anionic dyes orange IV, orange G and xylenol orange on chitin was studied, employing the Langmuir isotherm. The adsorption parameters were determined utilizing various linear regressions of the isotherm. The results showed that the adsorption capacity is dependent on pH. In acid pH, the polymer amino groups are protonated and the polymer chain is positively charged, with a predominance of adsorption through ion exchange. Van der Waals adsorption, as well as adsorption through hydrogen bonding, is also likely to occur to some extent. For xylenol orange, a linear regression was found, with an angular coefficient of 0.726 L mg-1. The temperature increase reduces adsorption capacity by chitin, due to the enhancement of the desorption step in the mechanism. DH values of -10.9 kJ mol-1 for orange G and -28.9 kJ mol-1 for orange IV prove the physical nature of the adsorption by these dyes on the chitin surface.

170 citations


Journal ArticleDOI
TL;DR: In this paper, a method for topology error identification based on the use of normalized Lagrange multipliers is proposed, which models circuit breakers as network switching branches whose statuses are treated as operational constraints in the state estimation problem.
Abstract: This paper introduces a method for topology error identification based on the use of normalized Lagrange multipliers. The proposed methodology models circuit breakers as network switching branches whose statuses are treated as operational constraints in the state estimation problem. The corresponding Lagrange multipliers are then normalized and used as a tool for topology error identification, in the same fashion as measurement normalized residuals are conventionally employed for analog bad data processing. Results of tests performed with the proposed algorithm for different types of topology errors are reported.

140 citations


Journal ArticleDOI
17 May 1998
TL;DR: In this paper, a new family of DC-to-DC converters featuring clamping action, PWM modulation and soft-switching in both active and passive switches, is proposed to overcome the limitations of clamped mode DC to DC converters.
Abstract: A new family of DC-to-DC converters featuring clamping action, PWM modulation and soft-switching (ZVS) in both active and passive switches, is proposed to overcome the limitations of clamped mode DC-to-DC converters. The new family of converters is generated and the new circuits are presented. As the resonant circuits absorb all parasitic reactances, including transistor output capacitance and diode junction capacitance, these converters are suitable for high-frequency operation. Principle of operation of the boost converter, theoretical analysis, simulation and experimental results are presented, taken from a laboratory prototype rated at 1600 W, input voltage of 300 V, output voltage of 400 V, and operating at 100 kHz. The measured efficiency at full load was 98%.

Journal ArticleDOI
TL;DR: It is concluded that dipyrone produces peripheral, spinal and supraspinal antinociception when assessed on formalin and capsaicin-induced pain as well as in glutamate-induced hyperalgesia in mice.

Journal ArticleDOI
TL;DR: A phenomenological field theory is used, reflecting the symmetries and conservation laws of sandpiles, to compare the driven dissipative sandpile with the corresponding fixed-energy model, showing that the driven model exhibits a fundamentally different approach to the critical point.
Abstract: We use a phenomenological field theory, reflecting the symmetries and conservation laws of sandpiles, to compare the driven dissipative sandpile, widely studied in the context of self-organized criticality, with the corresponding fixed-energy model. The latter displays an absorbing-state phase transition with upper critical dimension $d_c=4$. We show that the driven model exhibits a fundamentally different approach to the critical point, and compute a subset of critical exponents. We present numerical simulations in support of our theoretical predictions.

Journal ArticleDOI
TL;DR: Most of the set accelerators used today are based on alkali aluminates in combination with carbonates and hydroxides and produced in both liquid and powder form as discussed by the authors.
Abstract: A variety of additives and admixtures are added to shotcrete to improve strength, adhesiveness, cohesiveness, freezing/thawing and abrasion resistance characteristics, and reduce rebound. Accelerators are being used increasingly in both dry- and wetprocess applications. Accelerators are common in the dry process to increase early strength and reduce dust and rebound and in the wet process are used to achieve rapid set and early strength. The choice of a particular accelerator and its dosage is largely governed by the setting time required for the shotcrete application. Various watersoluble salts of the alkali metals can be used to accelerate the setting of cement. Most of the set accelerators used today are based on alkali aluminates in combination with carbonates and hydroxides and produced in both liquid and powder form. The performance of these accelerators depends on the cement chemical composition and fineness, and the presence of mineral additions such as flyash, and blastfurnace slag. This performance is generally evaluated using setting tests on cement/ accelerator pastes despite the belief of some researchers that this procedure can produce misleading results. This paper describes the main accelerators used in shotcrete and presents some results of field tests performed on shocrete panels evaluating the behavior of different accelerators. Particular attention is given to a new liquid alkalifree shotcrete accelerator that showed a very interesting behavior at very early ages and no strength loss at later ages. The early strengths were evaluated using non-destructive tests (Constant Depth Penetrometer and Constant Energy Penetrometer).

Journal ArticleDOI
TL;DR: A method for the determination of Cu, As, Se, Cd, In, Hg, Tl, Pb and Bi in waters and in biological materials by inductively coupled plasma mass spectrometry, after an on-line separation, is described in this article.

Journal ArticleDOI
TL;DR: A clinical and epidemiological study of 267 cases of envenomation by Loxosceles spp.
Abstract: A clinical and epidemiological study of 267 cases of envenomation by Loxosceles spp. (loxoscelism), notified to Centro de Informacoes Toxicologicas de Florianopolis (Santa Catarina State, Brazil), was conducted between January 1985 and December 1995. Most of the incidents occurred along the coast of the mid-southern region of the state, during the warmest months. L. laeta and L. intermedia were identified as the causative agents. Cutaneous loxoscelism was clinically diagnosed in 232 (86·9%) patients with local pain (86·5%), oedema (80·5%), hyperaemia (79·8%) and necrosis (56·9%). Cutaneous-visceral loxoscelism was detected in 35 patients (13·1%) with intravascular haemolysis, manifested by jaundice (68·6%), oliguria (45·7%), dark urine (28·6%), haemorrhage (25·7%), anuria (8·6%) and shock (2·9%), besides the cutaneous effects. Specific antivenom was given to 125 patients (46·8%) and only 8(6·5%) had mild reactions. Acute renal failure was observed in 17 cases (6·4%); 4 patients (1·5%) died, all of whom were children under 14 years old.

Journal ArticleDOI
TL;DR: In this paper, an optical spectral synthesis analysis for the nuclei of 20 Seyfert 2 and 4 Radio Galaxies, using a base of stellar population templates of different ages and metallicities and a power-law continuum, is presented.
Abstract: We present the results of an optical spectral synthesis analysis for the nuclei of 20 Seyfert 2 and 4 Radio Galaxies, using a base of stellar population templates of different ages and metallicities and a power-law continuum. Compared with the stellar population of elliptical galaxies, we find that Seyfert 2s usually have a smaller contribution from old metal rich stars (10 Gyr, Z>=Z_o), and a larger contribution from stars with 100 Myr. We also find that the contributions from stars with age <=10 Myr and from a power law continuum are small, rarely exceeding 5 per cent. These results show that the general assumption of elliptical galaxies as stellar population templates for these objects is incorrect, also implying that the excess blue continuum frequently found in their nuclear spectra is probably due to this template mismatch. We find a considerable contribution from 100 Myr stars (~5 per cent), which can be interpreted from the point of view of models where the fueling of the AGN is done by interactions/mergers.

Journal ArticleDOI
TL;DR: Results for a Berea sandstone sample show that the mean pore size distribution, obtained taking several serial cross-sections of the reconstructed 3D porous structure into account, is in good agreement with the original thresholded 2D image.

Journal ArticleDOI
TL;DR: A detailed analysis of the interactions between Tursiops truncatus and the artisanal fishing of mullets is presented at two localities in the south of Brazil: Laguna and Inibe/Tramandai.
Abstract: A detailed analysis of the interactions between Tursiops truncatus (Montagu, 1821) and the artisanal fishing of mullets (Mugil spp.) is presented at two localities in the south of Brazil: Laguna (Santa Catarina) and Inibe/Tramandai (Rio Grande do Sul). Its behavioral strategies and the advantages of their association are re-described and quantified based on the success of the capture and on the selectivity of the prey sizes. The mullets are the main resource involved (92% to 75%) both at numerical level and as biomass. Twenty individuals of Tursiops truncatus participated in the interactions in Laguna and 9 in Imbe/Tramandai. The participation and learning of calves is also reported.

Journal ArticleDOI
01 Sep 1998-Pain
TL;DR: Endothelin‐1 causes nociception in the rat when injected intra‐articular into the naive knee‐joint, whereas both ETA and ETB receptors contribute to its action in the carrageenan‐primed joint, which is mediated to a large extent via endothelin release and activation ofETB receptors.
Abstract: Endothelin-1, unlike the selective endothelin ETB receptor agonist sarafotoxin S6c, causes nociception in the rat when injected intraarticularly into the naive knee-joint. By using selective antagonists, the present study further characterizes the receptors underlying the articular nociceptive actions of endothelin-1, as well as the possible contribution of endogenous endothelins towards nociception induced by carrageenan or E. coli lipopolysaccharide (LPS) in this tissue. Nociception was evaluated by placing the animal for 1 min each hour on a revolving (3 rpm) cylinder and measuring the increase in time the hindpaw of the limb affected by the intra-articular (i.a.) injection of the nociceptive agent, failed to touch its metallic surface (i.e. paw elevation time, PET). In naive joints, endothelin-1 (120 pmol) increased the area under the PET curve (AUC 0-6 h, in arbitrary units) from 61+/-3 (control) to 156+/-12. This nociceptive effect was reduced by prior intravenous (i.v.) injection of the mixed ET(A)/ET(B)receptor antagonist bosentan (by 54 and 73% with 10 and 30 mg/kg) or i.a. administration of the selective ETA receptor antagonist BQ-123 (cyclo [D-Asp-Pro-D-Val-Leu]; by approximately/= 45% with 10 or 30 nmol), but was unaffected by the selective ET(B) receptor antagonist BQ-788 (N-cis-2,6-dimethyl-piperidinocarbonyl-L-gamma-methoxycarbonyl- tryptophanil-D-norleucine; 10 nmol). Prior joint challenge with carrageenan (300 microg) 72 h beforehand (i.e. priming) rendered the joint more sensitive to nociception induced by either endothelin-1 or sarafotoxin S6c (15, 30 and 60 pmol). Responses elicited by endothelin (30 pmol) in the primed joint were sensitive to inhibition by either BQ-123 or BQ-788 (each causing approximately/= 80% inhibition at 10 nmol). Priming also enhanced PET responses to carrageenan itself and to LPS (1 microg) markedly and persistently, increasing the area under the curve (AUC 0-12 h, in arbitrary units) from 241+/-19 to 409+/-50 and from 312+/-40 to 466+/-25, respectively (P < 0.05), without changing that measured following vehicle injection (from 121+/-3 to 117+/-4). Bosentan (up to 30 mg/kg, i.v.) failed to modify nociception caused by carrageenan or LPS in naive joints, by carrageenan in the primed joint, or control PET responses. LPS-induced nociception in the primed joint, however, was inhibited by 52 to 56% by bosentan (3 or 10 mg/kg) or 59% by local injection of the selective endothelin ET(B) receptor antagonist BQ-788 (10 nmol, i.a.), but was unaffected by the selective endothelin ETA receptor antagonist BQ-123. Thus, nociception induced by endothelin-1 in the naive joint is mediated largely via endothelin ETA receptors, whereas both ET(A)and ET(B) receptors contribute to its action in the carrageenan-primed joint. Furthermore, LPS-induced nociception in the primed joint is mediated to a large extent via endothelin release and activation of ET(B) receptors within the joint itself. These findings may be relevant to the etiology of pain underlying chronic arthritic disease in humans.

Journal ArticleDOI
TL;DR: In this article, a long-slit spectroscopic study of 38 active and four normal galaxies was conducted to characterize the stellar population in these galaxies and detect the presence of a featureless continuum underlying the starlight spectral component.
Abstract: We present the results of a long-slit spectroscopic study of 38 active and four normal galaxies. Stellar absorption features, continuum colours and their radial variations are analysed in an effort to characterize the stellar population in these galaxies and detect the presence of a featureless continuum underlying the starlight spectral component. Spatial variations of the equivalent widths of conspicuous absorption lines and continuum colours are detected in most galaxies. Star-forming rings, in particular, leave clear fingerprints in the equivalent widths and colour profiles. We find that the stellar populations in the inner regions of active galaxies present a variety of characteristics, and cannot be represented by a single starlight template. Dilution of the stellar lines by an underlying featureless continuum is detected in most broad-lined objects, but little or no dilution is found for most of the 20 type 2 Seyferts in the sample. Colour gradients are also ubiquitous. In particular, all but one of the observed Seyfert 2s are redder at the nucleus than in its immediate vicinity. Possible consequences of these findings are briefly outlined.

Journal ArticleDOI
TL;DR: In this article, the Smith-predictor-based generalised predictive controller (GPC) is proposed to improve the robustness of mobile robot path tracking when predictive control algorithms are used.

Journal ArticleDOI
TL;DR: A cooperative expert system that is able to define feasible alternatives for the expansion of the electrical transmission system, taking into account the selection of feasible transmission routes, as well as the definition of the expansion plan itself.
Abstract: This paper describes a cooperative expert system for managing the transmission expansion planning process, taking into account the selection of feasible transmission routes, as well as the definition of the expansion plan itself. The use of an expert system is proposed to create a planning environment, which can not only emulate the human expert reasoning, but also represent appropriately all heuristic knowledge related to this problem. The main point of this system is the fact that it is able to define feasible alternatives for the expansion of the electrical transmission system. Afterwards, the expert system executes a network flows program, which determines the minimum cost expansion plan. The developed prototype is tested with a realistic system of 500 busbars.

Journal ArticleDOI
TL;DR: A summary of the problems related to the systematics of primary and secondary Brazilian anophelines vectors of malaria is presented.
Abstract: A summary of the problems related to the systematics of primary and secondary Brazilian anophelines vectors of malaria is presented.

Journal ArticleDOI
TL;DR: It was found that fractions as well as kaurenoic acid and luteolin exhibit marked antinociceptive action in mice using acetic acid-induced writhing, more active than some well-known analgesic drugs, such as acetyl salicylic acid, acetaminophen, dipyrone and indomethacin.

Journal ArticleDOI
01 Oct 1998-Polymer
TL;DR: In this article, the equilibrium constants of adsorption copper(II) in aqueous solutions were derived using non-linear regression methods and the degree of substitution of NH2 groups of the chitosan was 0.85.

Journal ArticleDOI
TL;DR: The hemocytes of two palaemonids and one penaeid were characterized using light and transmission electron microscopy (TEM) as mentioned in this paper, and the blood cells in all three species were classified as hyaline hemocytes (HH), small granule hemocyte (SGH), and large granule Hemocytes (LGH).
Abstract: The hemocytes of two palaemonids and one penaeid were characterized using light and transmission electron microscopy (TEM). The blood cells in all three species were classified as hyaline hemocytes (HH), small granule hemocytes (SGH), and large granule hemocytes (LGH). The HH are unstable hemocytes with a characteristic high nucleo-cytoplasmic ratio. Their cytoplasm appears particularly dense and has from few to numerous granules that often exhibit a typical striated substructure. In both palaemonids, the great majority of the HH contain numerous granules, whereas in Penaeus paulensis, a small number of these cells have few or no granules. The cytoplasm of some HH of the penaeid exhibits typical electron-dense deposits. The granulocytes, LGH and SGH, contain abundant electron-dense granules that are usually smaller in the SGH. In both hemocyte types, the cytosol, but not the granules, is rich in carbohydrates (PAS positive) and numerous vesicles contain acid phosphatase (Gomori reactive). In all studied shrimps, the SGH and LGH were actively phagocytic when examined on blood cell monolayers incubated with the yeast Saccharomyces cerevisiae. A few mitotic figures (less than 1%) were observed in the granulocytes of P. paulensis, but not in the palaemonids. SGH is the main circulating blood cell type in both palaemonids, whereas HH is predominant in the penaeid. Based on morphological and functional features, it appears that the hyaline and the granular hemocytes of the three shrimp species represent different cell lineages.

Journal ArticleDOI
TL;DR: In this paper, the first through fourth moments of the order parameter, and various ratios, for several one-and two-dimensional models with absorbing-state phase transitions were determined, and a detailed analysis of the system-size dependence of these ratios was performed.
Abstract: We determine the first through fourth moments of the order parameter, and various ratios, for several one- and two-dimensional models with absorbing-state phase transitions. We perform a detailed analysis of the system-size dependence of these ratios and confirm that they are indeed universal for three models, the contact process, the $A$ model, and the pair contact process, belonging to the directed percolation universality class. Our studies also yield a refined estimate for the critical point of the pair contact process.

Proceedings ArticleDOI
07 Jul 1998
TL;DR: In this article, an active clamping mode circuit was proposed to recover the energy trapped in the leakage inductor of the current-fed push-pull converter, by means of an active clamping mode circuit.
Abstract: This paper introduces a new technique to recover the energy trapped in the leakage inductor of the current-fed push-pull converter, by means of an active clamping mode circuit. Theoretical analysis and experimental results, taken from a 800 W/40 kHz are presented in the paper. The studied converter also features ZVS (zero voltage switching) in all switches, preserving all the main properties of the original circuit. As a result, the efficiency is improved and the electromagnetic disturbances are minimized.

Journal ArticleDOI
01 Apr 1998-Talanta
TL;DR: The accuracy was checked for arsenic determination in a certified water, spiked tap water and synthetic mixtures of arsenite and arsenate and in agreement with the certified value of reference material at 95% confidence level.