Showing papers by "Rio de Janeiro State University published in 1996"

Tuning and test of fragmentation models based on identified particles and precision event shape data

Abstract: Event shape and charged particle inclusive distributions are measured using 750000 decays of the Z to hadrons from the DELPHI detector at LEP. These precise data allow a decisive confrontation with models of the hadronization process. Improved tunings of the JETSET, ARIADNE and HERWIG parton shower models and the JETSET matrix element model are obtained by fitting the models to these DELPHI data as well as to identified particle distributions from all LEP experiments. The description of the data distributions by the models is critically reviewed with special importance attributed to identified particles.

Empowerment, community mobilization and social change in the face of HIV/AIDS

Abstract: In the 15 years since it was identified HIV/AIDS has spread rapidly throughout the world. While our basic understanding of the epidemiology of HIV and the development of treatment technologies has improved it is predicted that 90% of the pandemic will affect developing countries which lack the resources to achieve prevention care and treatment. The early to mid 1990s however have given shape to a second set of developments which represent a transformation of the paradigms which have guided response to the epidemic. First despite an apparent reduction in the global response to HIV/AIDS critical thinking about the social cultural economic and political etiology of the disease has expanded from issues of individual risk to those of social vulnerability. Secondly this growing perception of the social dynamics of HIV/AIDS has led to revision in the dominant theories and models which guided HIV/AIDS prevention efforts (AIDS education and empowerment) to encompass multi-dimensional models of collective empowerment and community mobilization as effective prevention strategies. Finally the struggle to control HIV/AIDS is being viewed as part of a struggle to achieve far-reaching social justice and social change to address the underlying issues which contribute to the spread of the disease. Focusing on these issues presents an opportunity to develop a truly global coalition which will respond to the challenge of HIV/AIDS by overcoming the gaps which divide us and by in fact increasingly expanding the definition of "us" to include "them."

Effect of niflumic acid on noradrenaline-induced contractions of the rat aorta

Abstract: 1 The effects of niflumic acid, an inhibitor of calcium-activated chloride channels, were compared with the actions of the calcium channel antagonist nifedipine on noradrenaline-evoked contractions in isolated preparations of the rat aorta 2 The cumulative concentration-effect curve to noradrenaline (NA) was depressed by both nifedipine and niflumic acid in a reversible and concentration-dependent manner The degree of inhibition of the maximal contractile response to NA (1 microM) produced by 10 microM niflumic acid (38%) was similar to the effect of 1 microM nifedipine (39%) 3 Contractions to brief applications (30 s) of 1 microM NA were inhibited by 55% and 62% respectively by 10 microM niflumic acid and 1 microM nifedipine 4 In the presence of 01 microM nifedipine, niflumic acid (10 microM) produced no further inhibition of the NA-evoked contractions Thus, the actions of niflumic acid and nifedipine were not additive 5 In Ca-free conditions the transient contraction induced by 1 microM NA was not inhibited by niflumic acid (10 microM) and therefore this agent does not reduce the amount of calcium released from the intracellular store or reduce the sensitivity of the contractile apparatus to calcium 6 Niflumic acid 10 microM did not inhibit the contractions produced by KCl (up to 120 mM) which were totally blocked by nifedipine Contractions induced by 25 mM KCl were completely inhibited by 1 microM levcromakalim but were unaffected by niflumic acid 7 It was concluded that niflumic acid produces selective inhibition of a component of NA-evoked contraction which is probably mediated by voltage-gated calcium channels These data are consistent with a model in which NA stimulates a calcium-activated chloride conductance which leads to the opening of voltage-gated calcium channels to produce contraction

Gram-chromotrope: a new technique that enhances detection of microsporidial spores in clinical samples.

Abstract: SUMMARY We have developed a new staining procedure that combines the traditional Gram staining for bacteria and the Weber's chromotrope staining method, the standard technique for the detection of microsporidia spores in clinical Specimens. This “Gram-chromotrope” staining technique enhances the staining characteristics of microsporidia spores and facilitates the easy detection and differentiation of spores from other microorganisms that are found in clinical specimens, especially stool samples. This new technique is fast, reliable, and simple to perform, and can be easily adapted for use in clinical laboratories.

Energy dependence of the differences between the quark and gluon jet fragmentation

Abstract: Three jet events arising from decays of the Z boson, collected by the DELPHI detector, were used to measure differences in quark and gluon fragmentation. Gluon jets were anti-tagged by identifying b quark jets. Unbiased quark jets came from events with two jets plus one photon. Quark and gluon jet properties in different energy ranges were compared for the first time within the same detector. Quark and gluon jets of nearly the same energy in symmetric three jet event topologies were also compared. Using three independent methods, the average value of the ratio of the mean charged multiplicities of gluon and quark jets is = 1.241 ± 0.015 (stat.) ± 0.025 (syst.). Gluon jets are broader and produce fragments with a softer energy spectrum than quark jets of equivalent energy. The string effect has been observed in fully symmetric three jet events. The measured ratio R_{gamma} of the charged particle flow in the qoverline{q} inter-jet region of the qar{q}g and qar{q}gamma samples agrees with the perturbative QCD expectation. The dependence of the mean charged multiplicity on the hadronic center-of-mass energy was analysed in photon plus n-jet events. The value for alpha_s(M_Z) determined from these data using a QCD prediction with corrections at leading and next-to-leading order is αs(MZ)= 0.116 ± 0.003 (stat.) ± 0.009 (syst.).

Search for light top squarks in pp collisions at s = 1.8 tev

Abstract: We present a search for pair produced top squarks, the supersymmetric partners of the top quark, using the D0 detector at the Fermilab Tevatron pp collider. We consider a scenario in which the lighter of the two top squarks t 1 decays with 100% branching fraction to a charm quark and the lightest neutralino χ 1 0 yielding a signal of two acollinear jets with missing transverse energy. We observe 3 events while we expect 3.5±1.2 events from the known standard model processes. We exclude at the 95% confidence level a significant region of the m t 1 - m χ 1 0 parameter space. The highest m t 1 value we exclude is 93 GeV/c 2 with a corresponding m χ 1 0 value of 8 GeV/c 2 .

The involvement of nitric oxide in the anti-Candida albicans activity of rat neutrophils.

Abstract: Rat peritoneal neutrophils (PMN) spontaneously release nitric oxide (NO) when incubated in vitro. Addition of the NO synthase inhibitor L-monomethylarginine (L-NMMA) to the PMN reduces NO production and impairs the killing of the yeast Candida albicans, both effects being reversed by L-arginine. These data strongly suggest that oxidative metabolism of L-arginine by PMN is involved in the candidacidal activity of these cells. Rat blood PMN, which do not produce significant amounts of NO, exhibit a reduced killing capacity compared with peritoneal cells, except when they are obtained from lipopolysaccharide (LPS)-treated rats. In this case they produce measurable amounts of nitrite and express high fungicidal activity in vitro. Confirming the candidacidal activity of NO, the exposure of the C. albicans cultures to different concentrations of NO donors leads to a reduction in their survival. The candidacidal activity related to the NO pathway in rat PMN is phagocytosis dependent, since the activity can be inhibited by cytochalasin B. However, the oxidative products of oxygen released by rat PMN do not seem to be involved in their candidacidal activity, as incubation of the cells with phorbol myristate acetate (PMA) increases release of superoxide anion but does not affect the pattern of killing. Our results suggest that NO could be an important candidacidal pathway in rat neutrophils.

The Dilemma of the Crossing Vessel at the Ureteropelvic Junction: Precise Anatomic Study

Abstract: To maximize the success rate of endopyelotomy with minimal risk of complications, some debate still persists on the technique of incising the ureteropelvic junction (UPJ), patient selection, and prognostic factors. Also, some controversy exists concerning the vascular complications associated with the procedure. In order to give anatomic background to better clarifying the issue of a crossing vessel at the UPJ, we analyzed its vascular anatomic relations in 546 kidneys divided as following: 82 three-dimensional polyester resin corrosion endocasts of the collecting system together with the intrarenal arteries, 52 endocasts of the collecting system together with the intrarenal veins, 146 endocasts of the collecting system together with the intrarenal arteries and veins simultaneously, and 266 in situ dissected kidneys. In 65% of the endocasts, we found a prominent artery, vein, or both in close relation to the ventral surface of the UPJ. Among these cases, in 45%, the relation was with the inferior segmental artery. With respect to the presence of multiple renal arteries, in only 6.8% of the cases did an inferior polar artery cross anteriorly to the UPJ. In 6.2% of the endocasts, there was a direct relation between a large vessel and the dorsal surface of the UPJ. In additional 20.5% of the cases, there was a vessel crossing lower than 1.5 cm above the posterior surface of the UPJ. Considering these anatomic findings, it is conceivable that many of the vessels seen during angiography in a close relation to the UPJ and described as anomalous and etiologic in obstruction would be normal segmental arteries that do not cause UPJ obstruction. Also, on the basis of the anatomic findings, we advise that in endopyelotomy, the incision along the stenotic UPJ wall be created only at its lateral aspect.

Pseudomonas aeruginosa strains possess specific adhesins for laminin.

Abstract: Pseudomonas aeruginosa is a major human pathogen known to infect tissues that have been previously damaged in some way. In wounded human respiratory tissues, P. aeruginosa cells were found attached to exposed basement membranes following epithelial denudation, suggesting that the affinity for extracellular matrix proteins may account for the bacterium's opportunistic character. By using microtiter wells coated with different P. aeruginosa strains, we demonstrated that laminin binds to both colonizing bacterial strains, isolated from asymptomatic carriers, and strains isolated from infected patients. Binding of soluble laminin to piliated P. aeruginosa PAK and to the nonpiliated isogenic mutant PAK/p--was shown to be saturable. Binding of laminin to the piliated PAK strain was not different from binding to th nonpiliated PAK/p--strain but was significantly higher than binding to the avirulent, nonpiliated PAK-N1 rpoN mutant. By transmission electron microscopy, we localized the laminin-binding sites on a loose material in the outermost layer of the bacteria. Western immunoblotting results suggested that 57- and 59-kDa nonpilus adhesins from the microbial outer membranes account for the binding of P. aeruginosa to laminin. We speculate that bacterial affinity for laminin may be of biological significance in the pathogenesis of P. aeruginosa infection of injured tissues.

Effect of Thuya occidentalis on the labeling of red blood cells and plasma proteins with technetium-99m

Abstract: Thuya occidentalis is used in popular medicine in the treatment of condyloma and has antibacterial action. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used for several evaluations in nuclear medicine. This labeling depends on a reducing agent, usually stannous ion. Any drug which alters the labeling of the tracer could be expected to modify the disposition of the radiopharmaceutical. We have evaluated the influence of T. occidentalis extract on the labeling of RBC and plasma proteins with 99mTc. Blood was withdrawn and incubated with T. occidentalis (0.25; 2.5; 20.5; and 34.1 percent v/v). Stannous chloride (1.2 micrograms/ml) was added and then 99mTc was added. Plasma (P) and blood cells (BC) were isolated, also precipitated with trichloroacetic acid and soluble (SF) and insoluble fractions (IF) separated. The analysis of the results shows that there is a decrease in radioactivity (from 97.64 to 75.89 percent) in BC with 34.1 percent of the drug. In the labeling process of RBC with 99mTc, the stannous and pertechnetate ions pass through the membrane, so we suggest that the T. occidentalis effect can be explained (i) by an inhibition of the transport of these ions, (ii) by damage in membrane, (iii) by competition with the cited ions for the same binding sites, or (iv) by possible generation of reactive oxygen species that could oxidize the stannous ion.

Bachelard: o filósofo da desilusão

Abstract: Este artigo se propoe a analisar os principais aspectos da obra epistemologica de Gaston Bachelard, notadamente sua concepcao de erro e verdade e sua perspectiva descontinuista. Argumentamos que esta perspectiva se expressa pelas concepcoes de fenomenotecnica, ruptura, obstaculos epistemologicos, filosofia do nao, recorrencia historica, racionalismos setoriais e alcanca seu apice com a proposta da razao polemica. Assim, enquanto um filosofo da desilusao, da retificacao constante, Bachelard construiu uma epistemologia essencialmente historica e questionadora das coercoes de um racionalismo unitario, que tem sua base na tradicao do pensamento.

In vitro action of various carbamide peroxide gel bleaching agents on the microhardness of human enamel.

Abstract: The authors verified a decrease in human enamel microhardness after application of the following carbamide peroxide gel bleaching agents for 8 hours daily for 1 week: 10% Nite White, 16% Nite White, Opalescence, Karisma Alpha and Perfect Smile. Statistical analysis showed that these agents caused a decrease in enamel microhardness. Nite White (16%) was the most effective in reducing enamel microhardness and Opalescente the least effective. Nite White (10%), Karisma Alpha and Perfect Smile fell into a statistically intermediate position.

Behaviour in Latin American men: implications for HIV/AIDS interventions.

Abstract: The single most deeply rooted feature of sexual culture in Latin America is the culture of machismo. Machismo is a complex ideological system that organizes gender relations hierarchically which establishes relations of power and domination between men and women. Same-sex relations between men are conceptualized within the framework of male-female relations. In Latin America the penetrating partner in same-sex interactions may maintain a sense of a fundamentally male identity. Thus he may not distinguish himself from other macho males. The receiving or effeminate partner faces the severest stigma in Latin America. Regardless of the type of sexual relations sexual practices are socially and culturally constructed within the context of sexual scripts. The broader conceptual frameworks of most HIV/AIDS prevention programs and interventions focus on psychologically grounded theories of individual behavior change rather than on more sociologically grounded approaches to community development and mobilization. Projects in Latin America have revealed many important insights that guide decision makers to reevaluate some elements of models that appear to contribute to the guidance of past HIV/AIDS behavioral interventions. Perhaps the concept of a behavioral intervention may be somewhat a misnomer because most AIDS prevention programs do not directly intervene at the level of behavior. Instead they tend to intervene at the level of social and cultural representations--the level of the subjective and intersubjective meanings held by people about their behaviors. The possibilities of behavior changes are conditioned by a range of social cultural economic and political factors or forces. These conditions may actually be beyond the possibility of any HIV/AIDS prevention program to effectively influence behavior. Nevertheless HIV/AIDS prevention programs should try to integrate as much as possible a concern with these factors into the design and implementation of prevention programs.

Undernutrition during early lactation as an alternative model to study the onset of diabetes mellitus type ii

Abstract: In order to characterize an alternative animal model for the study of diabetes mellitus type II onset, we compared the effects of a diet containing 8% of protein (LPD) and a normal diet containing 25% of protein supplied to the dams during the first 12 days of lactation. We studied in the pups the growth evolution and, when they develop into adults (60 days), the glucose tolerance test (GTT) and the insulin secretion, in response to stimulatory concentrations of glucose. The weight of the two groups were significantly different at 60 days of age (LPD = 179 +/- 19 g; NPD = 186 +/- 18 g). The GTT ten minutes after iv glucose administration showed a significant increase of blood glucose concentration of the LPD group (LPD = 550 +/- 17 mg/dl; NPD = 425 +/- 13 mg/dl, p < 0.001). The insulin secretion, four minutes after stimulation was found reduced in the LPD group (LPD = 1.1 +/- 0.08 muU/islet/min; NPD = 1.85 +/- 0.2 muU/islet/min.). The present study indicates insulin secretory and/or resistance impairment due to early undernutrition. Also, the data taken together suggest that undernutrition during early lactation can be used as an alternative model to study particular characteristics of the onset of diabetes mellitus type II.

Evolvable Systems in Hardware Design: Taxonomy, Survey and Applications

Abstract: This article proposes a taxonomy, presents a survey and describes a set of applications on Evolvable Hardware Systems (EHW). The taxonomy is based on the following properties: Hardware Evaluation Process, Evolutionary Approach, Target Application Area and Evolving Platform. Recent reported applications on EHW are also reviewed, according to the proposed taxonomy. Additionally, a set of digital design applications, developed by the authors are presented. The applications consist in evolving basic digital devices, and the main objective is to evaluate the performance of an EHW system in terms of chromosome representation and evaluation.

Thermal ecology of two sympatric skinks (Mabuya macrorhyncha and Mabuya agilis] in a Brazilian restinga habitat

Abstract: In a restinga habitat of southeastern Brazil, we studied some aspects of the thermal biology of two sympatric skinks (Mabuya macrorhyncha and Mabuya agilis) with distinct microhabitat preferences. The two species did not differ significantly in their mean body temperature. Sex and body size did not explain body temperature variation within either species. The body temperature of both species is significantly affected by air temperature, but only that of M. agilis is significantly influenced by sand surface temperature, presumably due to its more terrestrial habit compared to M. macrorhyncha. We found no significant seasonal variation in body temperature for either species, although environmental temperatures varied seasonally, indicating that both species may be selecting an optimal range of body temperatures, possibly through behavioural thermoregulation.

Isolated photon cross section in the central and forward rapidity regions in pp̄ collisions at √s = 1.8 TeV

Abstract: A measurement of the cross section for production of single, isolated photons is reported for transverse energies in the range of 10–125 GeV for two regions of pseudorapidity, |η| -1 of integrated luminosity accumulated in pp collisions at √s=1.8TeV and recorded with the D0 detector at the Fermilab Tevatron Collider. The background, predominantly from jets which fragment to neutral mesons, is estimated using the longitudinal shower shape in the calorimeter. In both pseudorapidity regions the cross section is found to agree with the next-to-leading order QCD prediction for 30≲E T γ ≲80GeV.

Colorimetric assay for lignin peroxidase activity determination using methylene blue as substrate

Abstract: A colorimetric method for determination of lignin peroxidase activity has been developed which is based on the demethylation of methylene blue. The use of this dye shows the practical advantage of using a wavelength in the visible region of spectrum. The method can be efficiently used for the enzyme quantification as its sensitivity is close to the veratryl alcohol assay.

Jet production via strongly interacting color-singlet exchange in pp̄ collisions

Abstract: A study of the particle multiplicity between jets with large rapidity separation has been performed using the D\O\ detector at the Fermilab Tevatron $p\bar{p}$ Collider operating at $\sqrt{s}=1.8$\,TeV. A significant excess of low-multiplicity events is observed above the expectation for color-exchange processes. The measured fractional excess is $1.07 \pm 0.10({\rm stat})~{ + 0.25}_{- 0.13}({\rm syst})\%$, which is consistent with a strongly-interacting color-singlet (colorless) exchange process and cannot be explained by electroweak exchange alone. A lower limit of $0.80\%$ (95\% C.L.) is obtained on the fraction of dijet events with color-singlet exchange, independent of the rapidity gap survival probability.