Showing papers by "Federal University of Rio de Janeiro published in 1995"
TL;DR: A cosmological implications of an ultralight pseudo Nambu-Goldstone boson is explored, which can reconcile dynamical estimates of the density parameter, ${\ensuremath{\Omega}}_{m}\ensure Math{\simeq}1}0.2$ with a spatially flat universe, consistent with limits from gravitational lens statistics.
Abstract: We explore the cosmological implications of an ultralight pseudo Nambu-Goldstone boson. With global spontaneous symmetry breaking scale $f\ensuremath{\simeq}{10}^{18}\mathrm{GeV}$ and explicit breaking scale comparable to Mikheyev-Smirnov-Wolfenstein neutrino masses, $M\ensuremath{\sim}{10}^{\ensuremath{-}3}\mathrm{eV}$, such a field, which acquires a mass ${m}_{\ensuremath{\varphi}}\ensuremath{\sim}{M}^{2}/f\ensuremath{\sim}{H}_{0}$, would currently dominate the energy density of the Universe. The field acts as an effective cosmological constant before relaxing into a condensate of nonrelativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, ${\ensuremath{\Omega}}_{m}\ensuremath{\sim}0.2$, with a spatially flat universe, yielding ${H}_{0}{t}_{0}\ensuremath{\simeq}1$ consistent with limits from gravitational lens statistics.
755 citations
TL;DR: In this paper, the authors presented the general equations that relate the new concepts of instantaneous active and reactive power theory and the well known theory of symmetrical components for the case of 3-phase 4-wire systems, where zero sequence components and harmonics may be present in both voltages and currents.
Abstract: This paper presents the general equations that relate the new concepts of instantaneous active and reactive power theory and the well known theory of Symmetrical Components, for the case of 3-phase 4-wire systems, where zero sequence components and harmonics may be present in both voltages and currents. Based on these equations, new control algorithms for 3-phase 4-wire shunt and series active filters for unbalanced power systems are proposed and validated through simulations. The control algorithms presented here are very important for active power filter design and also for FACTS technology reactive power compensators. >
328 citations
Book•
01 Jan 1995TL;DR: The theory of D-modules is a rich area of study combining ideas from algebra and differential equations, and it has significant applications to diverse areas such as singularity theory and representation theory as mentioned in this paper.
Abstract: The theory of D-modules is a rich area of study combining ideas from algebra and differential equations, and it has significant applications to diverse areas such as singularity theory and representation theory. This book introduces D-modules and their applications avoiding all unnecessary over-sophistication. It is aimed at beginning graduate students and the approach taken is algebraic, concentrating on the role of the Weyl algebra. Very few prerequisites are assumed, and the book is virtually self-contained. Exercises are included at the end of each chapter and the reader is given ample references to the more advanced literature. This is an excellent introduction to D-modules for all who are new to this area.
309 citations
TL;DR: Fish and hair samples as the best indicators of human methylmercury contamination were investigated in the main cities and villages along the Tapajós river basin and critical fish, areas, and more exposed human groups are identified.
272 citations
TL;DR: The overwhelming majority of the isolates shared a common pulsed-field gel electrophoresis pattern and carried mecA polymorph III in combination with Tn554 pattern B, indicating the presence of a single, epidemic MRSA clone spread over large geographic distances of Brazil.
Abstract: Staphylococcus aureus isolates from five large teaching hospitals and one medium-size community hospital located in geographically distant parts of Brazil, in the south and southeast (Rio de Janeiro, Niteroi, Sao Paulo, Porto Alegre) and in the north (Manaus), were tested for their antibiotic resistance patterns and genetic backgrounds. Eighty-five of the 152 isolates were identified as methicillin-resistant S. aureus (MRSA) by using a combination of an agar dilution screen and a mecA gene-specific DNA probe. All MRSA isolates were resistant to penicillin, erythromycin, gentamicin, oxacillin, and cephalothin, and the majority of isolates (74%) were also resistant to chloramphenicol, sulfamethoxazole-trimethoprim, ciprofloxacin, and clindamycin as well and were susceptible only to vancomycin. Isolates obtained from hospitals in Sao Paulo, Rio de Janeiro, Niteroi, and Porto Alegre (1,600 km from one another) and Manaus (3,700 km from Rio de Janeiro) were examined by a variety of molecular fingerprinting techniques: the nature of the mecA polymorph and Tn554 attachment sites and restriction fragment length polymorphism of genomic DNAs after SmaI restriction and separation of the digested DNA by pulsed-field gel electrophoresis. The overwhelming majority of the isolates shared a common pulsed-field gel electrophoresis pattern and carried mecA polymorph III in combination with Tn554 pattern B, indicating the presence of a single, epidemic MRSA clone spread over large geographic distances of Brazil.
233 citations
TL;DR: It is shown that, in monkeys viewing a similar texture field with a hole, the responses of extrastriate visual neurons with receptive fields covering the hole increase gradually to a level comparable to that elicited by the same texture without a hole.
Abstract: When we view a scene through one eye, we typically do not see the scotomas created by the optic disc and the blood vessels overlying the retinal surface. Similarly, when a texture field containing a hole is steadily viewed in peripheral vision (artificial scotoma), the hole appears to fill in with the surrounding texture in a matter of seconds, demonstrating that the visual system fills in information across regions where no information is available. Here we show that, in monkeys viewing a similar texture field with a hole, the responses of extrastriate visual neurons with receptive fields covering the hole increase gradually to a level comparable to that elicited by the same texture without a hole. The time course of these dynamic changes in activity parallels the time course of perceived filling-in of the hole by human observers, suggesting that this process mediates perceptual filling-in.
229 citations
21 May 1995
TL;DR: This note shows that the angular velocity feedback can be replaced by a nonlinear filter of the quarternion, thus removing the need of direct angular velocity measurement, and exploits the inherent passivity of the system.
Abstract: It is well known that the linear feedback of the quarternion of the attitude error and angular velocity globally stabilizes the attitude of a rigid body. In this note, we show that the angular velocity feedback can be replaced by a nonlinear filter of the quarternion, thus removing the need of direct angular velocity measurement. In contrast to other approaches, this design exploits the inherent passivity of the system; a dynamic observer reconstructing the velocity is not needed. An application of the proposed scheme is illustrated for the robot control problem. Simulation results are included to illustrate the theoretical results.
222 citations
TL;DR: In this paper, the basic information on human exposure to mercury due to gold mining activities in Anazon, total mercury (T-Hg) and methylmercuiy (MeHg), were determined for human hair, blood and/or urine saraples collected from populations living in gold mining area and fishing villages upstream of the Tapajos River basin.
Abstract: To obtain the basic information on human exposure to mercury (Hg) due to gold mining activities in Anazon, total mercury (T-Hg) and methylmercuiy (MeHg) were determined for human hair, blood and/or urine saraples collected from populations living in gold mining area and fishing villages upstream of the Tapajos River basin. Abnormally high levels of T-Hg were observed in hair and blood from all fishing villages investigated and more than 90% of T-Hg was in the form of MeHg in both samples, whereas in goldmining area the value were much lower and the %MeHg values varied widely (20–100%) with individuals even in blood samples. Urine from gold shop workers contained Hg mostly in inorganic form at 165 µg/g creatinine on the average, with the range of 20 to 450 µg/g creatinine. A good correlation between Hg in hair and blood was found in fishing villages and the ratios of hair Hg to blood Hg were very close to 250, generally established for MeHg. T-Hg and inorganic Hg levels in urine from gold shop workers were also significantly correlated with inorganic Hg in blood.
216 citations
TL;DR: In this paper, the authors used the Global Warming potential index (GWP) to quantitatively compare the integrated greenhouse effect of different gases and applied it to the case of emissions from some hydroelectric reservoirs in Brazil.
194 citations
TL;DR: In this paper, the authors evaluated the extent of environmental mercury pollution due to goldmining activities in the Amazon, and determined the concentrations of total mercury and methylmercury for human hair and fish samples from five fishing villages.
188 citations
TL;DR: Four phloroglucinols have been isolated from a petrol extract of the leaves and flowers of Hypericum brasiliense and were antibacterial against Bacillus subtilis in a TLC bioautographic assay.
Journal Article•
TL;DR: The data indicate that activation-induced CD4+ T cell death by apoptosis is a prominent feature of experimental infection with T. cruzi, and could play a role in immunosuppression and parasite persistence in infected hosts.
Abstract: Infection of mice with Trypanosoma cruzi, the causative protozoan agent of human Chagas' disease, leads to immunosuppression of the T cell compartment and to chronic cardiac inflammation which resembles the human infection. Recently, reinduction of programmed cell death by apoptosis in mature T cells has been demonstrated. It has been suggested that mature T cell apoptosis could play a role in immunosuppression caused by virus infection. In this report, we have investigated the occurrence of mature T cell apoptosis in murine experimental Chagas' disease. Infection with T. cruzi metacyclic forms led to a relative accumulation of CD8 T cells over CD4 T cells in the spleens of infected mice. Splenic T cells from T. cruzi-infected donors, but not from control littermates, died in vitro upon stimulation with T cell mitogens Con A and anti-TCR-alpha beta mAb in a dose-dependent fashion. DNA fragmentation into nucleosome-sized bands was detected in the supernatants of CD4+ T cells from infected origin, after stimulation with the T cell mitogen Con A. Upon in vitro stimulation with either anti-TCR-alpha beta or Con A, CD4+ T cells were susceptible to elimination, whereas CD8+ T cells were not. Splenic T cells from infected donors were markedly unresponsive to anti-TCR mAb in proliferative assays and underwent apoptosis in vitro, as assessed by electron microscopy. Apoptosis also occurred in vivo in the course of acute infection, as seen by DNA fragmentation in freshly explanted splenic cells and purified T cell subsets. The data indicate that activation-induced CD4+ T cell death by apoptosis is a prominent feature of experimental infection with T. cruzi, and could play a role in immunosuppression and parasite persistence in infected hosts.
TL;DR: In this article, the authors compared the evaporation and infiltration of tropical rainforest and pasture, near to Manaus, Brazil from October 1990 to February 1992 using measurements of soil water storage over a depth of 2 m.
TL;DR: The findings can be summarized as follows: hippocampal neurons express at least three subtypes of CNS nAChRs, and there is an ACh-insensitive site on neuronal and nonneuronal nA ChRs through which the receptor channel can be activated.
Abstract: The diversity of neuronal nicotinic receptors (nAChRs) in addition to their possible involvement in such pathological conditions as Alzheimer's disease have directed our research towards the characterization of these receptors in various mammalian brain areas. Our studies have relied on electrophysiological, biochemical, and immunofluorescent techniques applied to cultured and acutely dissociated hippocampal neurons, and have been aimed at identifying the various subtypes of nAChRs expressed in the mammalian central nervous system (CNS), at defining the mechanisms by which CNS nAChR activity is modulated, and at determining the ion permeability of CNS nAChR channels. Our findings can be summarized as follows: (1) hippocampal neurons express at least three subtypes of CNS nAChRs--an alpha 7-subunit-bearing nAChR that subserves fast-inactivating, alpha-BGT-sensitive currents, which are referred to as type IA, and alpha 4 beta 2 nAChR that subserves slowly inactivating, dihydro-beta-erythroidine-sensitive currents, which are referred to as type II, and an alpha 3 beta 4 nAChR that subserves slowly inactivating, mecamylamine-sensitive currents, which are referred to as type III; (2) nicotinic agonists can activate a single type of nicotinic current in olfactory bulb neurons, that is, type IA currents; (3) alpha 7-subunit-bearing nAChR channels in the hippocampus have a brief lifetime, a high conductance, and a high Ca2+ permeability; (4) the peak amplitude of type IA currents tends to rundown with time, and this rundown can be prevented by the presence of ATP-regenerating compounds (particularly phosphocreatine) in the internal solution; (5) rectification of type IA currents is dependent on the presence of Mg2+ in the internal solution; and (6) there is an ACh-insensitive site on neuronal and nonneuronal nAChRs through which the receptor channel can be activated. These findings lay the groundwork for a better understanding of the physiological role of these receptors in synaptic transmission in the CNS.
TL;DR: The salivary anticoagulant of the blood-sucking bug Rhodnius prolixus was purified to homogeneity using a protocol consisting of weak cation-exchange, DEAE, hydrophobic-interaction and octadecyl reverse-phase chromatography, yielding a protein with the same N-terminal sequence as nitrophorin 2.
Abstract: The salivary anticoagulant of the blood-sucking bug Rhodnius prolixus was purified to homogeneity using a protocol consisting of weak cation-exchange, DEAE, hydrophobic-interaction and octadecyl reverse-phase chromatography, yielding a protein with the same N-terminal sequence as nitrophorin 2, one of the four NO haem protein carriers present in the salivary glands of Rhodnius with a molecular mass of 19689 Da [D. Champagne, R.H. Nussenzveig and J.M.C. Ribeiro, (1995) J. Biol. Chem. 270, in the press]. To exclude the possibility of the nitrophorin being a contaminant, another chromatographic protocol was performed, consisting of chromatofocusing followed by strong-cation-exchange chromatography. Again the anticoagulant was eluted with nitrophorin 2. Nitrophorin 2 inhibits coagulation Factor VIII-mediated activation of Factor X and accounts for all the anti-clotting activity observed in Rhodnius salivary glands.
TL;DR: The variability of paternal age effect in these new mutations could be due, among other reasons, to the high proportion of germ-line mosaicism in OI parents, or to the localization of the AC gene, mapped to the 4p16.3 region, in the neighborhood of an unstable DNA area.
Abstract: The paternal ages of nonfamilial cases of achondroplasia (AC) (n = 78), thanatophoric dysplasia (TD) (n = 64), and osteogenesis imperfecta (OI) (n = 106), were compared with those of matched controls, from an Italian Indagine Policentrica Italiana sulle Malformazioni Congenite and a South American Estudio Colaborativo Latinoamericano de Malformaciones Congenitas series. The degree of paternal age effect on the origin of these dominant mutations differed among the three conditions. Mean paternal age was highly elevated in AC, 36.30 +/- 6.74 years in the IPIMC, and 37.19 +/- 10.53 years in the ECLAMC; less consistently elevated in TD, 33.60 +/- 7.08 years in the IPIMC, and 36.41 +/- 9.38 years in the ECLAMC; and only slightly elevated in OI in the ECLAMC, 31.15 +/- 9.25 years, but not in the IPIMC, 32.26 +/- 6.07 years. Increased maternal age or birth order in these conditions disappeared when corrected for paternal age. Approximately 50% of AC and TD cases, and only 30% of OI cases, were born to fathers above age 35 years. For AC and TD, the increase in relative incidence with paternal age fitted an exponential curve. The variability of paternal age effect in these new mutations could be due, among other reasons, to the high proportion of germ-line mosaicism in OI parents, or to the localization of the AC gene, mapped to the 4p16.3 region, in the neighborhood of an unstable DNA area.
TL;DR: a Escola Paul&a de Medicina, Rua Botucatu, 862, CEP 04023-062, Stio Pa&o, Brazil b Institute de Quimica da USP, Sao Paula, Brazil ’ Institute de Inuestigaciones en Engenharia Genetica y Biologia Molecular, Buenos Aires.
TL;DR: The kinetics of in vitro sialylation of these O-linked oligosaccharides by the T. cruzi trans-sialidase are investigated and it is shown that incorporation of one molecule of sialic acid hinders entry of a second molecule when two potential acceptor sites are present.
TL;DR: In this paper, smoke particulate matter was sampled by high volume filtration from a controlled burn of forest litter in the northern forest reserve of INPA about 70 km north of Manaus, Amazonas.
TL;DR: Results suggest that 4-O-sulfation of the N-acetyl-β-D-galactosamine residues is essential for the anticoagulant activity of dermatan sulfate.
TL;DR: The functional importance of the restricted expression pattern is demonstrated by the severe projection errors of axons in the first and second optic chiasms in loss of function mutants and in transformants that express the irreC-rst protein globally.
Journal Article•
TL;DR: If certain preoperative and postoperative steps are carefully followed and meticulous debridement of the alveolus is done during the surgical procedure, immediate implants can be successfully placed into chronically infected sites.
Abstract: Placement of immediate implants is a routine clinical procedure. However, certain clinical conditions, especially the presence of infected sites, are considered to be contraindications for the immediate implant. Based on clinical experience, it is proposed that if certain preoperative and postoperative steps are carefully followed and meticulous debridement of the alveolus is done during the surgical procedure, immediate implants can be successfully placed into chronically infected sites. The advantages of this procedure are discussed.
TL;DR: An increase in pH, inhibiting toxin activity and the depletion of simple sugars, may have promoted an increase in yeast diversity in the later stages of decomposition, and provided a patchy environment for the drosophilids sharing this ephemeral substrate.
Abstract: The succession of yeasts colonizing the fallen ripe amapa fruit, from Parahancornia amapa, was examined. The occupation of the substrate depended on both the competitive interactions of yeast species, such as the production of killer toxins, and the selective dispersion by the drosophilid guild of the amapa fruit. The yeast community associated with this Amazon fruit differed from those isolated from other fruits in the same forest. The physiological profile of these yeasts was mostly restricted to the assimilation of a few simple carbon sources, mainly L-sorbose, D-glycerol, DL-lactate, cellobiose, and salicin. Common fruit-associated yeasts of the genera Kloeckera and Hanseniaspora, Candida guilliermondii, and Candida krusei colonized fruits during the first three days after the fruit fell. These yeasts were dispersed and served as food for the invader Drosophila malerkotliana. The resident flies of the Drosophila willistoni group fed selectively on patches of yeasts colonizing fruits 3 to 10 days after the fruit fell. The killer toxin-producing yeasts Pichia kluyveri var. kluyveri and Candida fructus were probably involved in the exclusion of some species during the intermediate stages of fruit deterioration. An increase in pH, inhibiting toxin activity and the depletion of simple sugars, may have promoted an increase in yeast diversity in the later stages of decomposition. The yeast succession provided a patchy environment for the drosophilids sharing this ephemeral substrate.
TL;DR: In this paper, total mercury concentrations in the more representative environmental (air, soil, bottom sediments, fishes and plants) and human (hair and urine) indicators, collected in the last 7 years in different goldmining areas (garimpos) are presented and discussed.
TL;DR: A heme-binding protein has been isolated and characterized from both the hemolymph and oocytes of the blood-sucking insect, Rhodnius prolixus, and it differs from hemoglobin in having a distinct amino-acid composition and NH2-terminal sequence.
TL;DR: Oral treatment with Kalanchoe pinnata significantly delayed onset of disease as compared to untreated mice or mice receiving Kp by the intravenous or topical routes and the effect was long-lasting, comparable to the reference antileishmanial drug Glucantime.
TL;DR: The appearance of large multivesicular bodies, especially after ketoconazole treatment, increased amount of lipid inclusions as well as numerous, polymorphic volutin granules, particularly in terbinafine‐treated cells may indicate the existence of an unusual autophagic process in cells treated with ergosterol biosynthesis inhibitors.
Abstract: The antiproliferative effects and ultrastructural alterations induced in vitro by two antifungal compounds, the azole ketoconazole and the allylamine terbinafine on Leishmania amazonensis are reported. Promastigotes treatment with ketoconazole and terbinafine induced growth arrest and cell lysis in 72 hours. Combination of the two agents produced additive effects on promastigote axenic growth and synergistic effects on intracellular amastigote proliferation. The amastigotes, either axenically grown or infecting murine macrophages, were about 100-fold more sensitive to the drugs. These compounds induced the appearance of large multivesicular bodies, especially after ketoconazole treatment, increased amount of lipid inclusions as well as numerous, polymorphic volutin granules, particularly in terbinafine-treated cells. Multivesicular bodies were observed in close apposition with organelles such as mitochondria, which also showed alterations in the distribution and appearance of cristae, and the formation of paracrystalline arrays within the matrix. Some cells presented large portions of cytoplasm wrapped by endoplasmic reticulum and many parasites also presented myelin-like endoplasmic reticulum profiles. Such alterations together with the strong acid phosphatase activity observed in the multivesicular bodies and volutin granules may indicate the existence of an unusual autophagic process in cells treated with ergosterol biosynthesis inhibitors.
TL;DR: Oliveira et al. as discussed by the authors showed that heme-binding protein (RHBP) in Rhodnius prolixus hemolymph prevents peroxidation of both linolenic acid liposomes and lipophorin.
TL;DR: Strongyloidiasis was highly prevalent among patients with hematologic malignancies in Brazil and Occurrence of the disseminated disease syndrome seems to be unusual.
Abstract: We retrospectively studied 343 consecutive patients treated between 1979 and 1992. Ninety patients whose stool was not examined were excluded. Fifty-three patients with strongyloidiasis were compared with 200 controls with regard to outcomes and the following characteristics : age, sex, underlying disease, use of corticosteroids, abdominal pain, diarrhea, fever, pulmonary symptoms, and eosinophilia. Patients with strongyloidiasis more commonly had eosinophilia (P =.01) and fever (P =.03). There was a single but fatal case of the disseminated disease syndrome (1.9% of patients with strongyloidiasis). In multiple logistic regression analysis, the factors predictive for strongyloidiasis were schistosomiasis (odds ratio [OR], 6.58), ascariasis (OR, 2.78), and the use of steroids (OR, 2.29). Strongyloidiasis was highly prevalent among patients with hematologic malignancies in Brazil. Occurrence of the disseminated disease syndrome seems to be unusual.
TL;DR: In this article, the influence of preparation method and loading of CeO 2 on the interaction of Pd/CeO 2 /Al 2 O 3 catalysts was studied by temperature-programmed reduction, hydrogen chemisorption and X-ray photoelectron spectroscopy measurements.
Abstract: The influence of the preparation method and loading of CeO 2 on the interaction of Pd/CeO 2 /Al 2 O 3 catalysts was studied. The materials were characterized by temperature-programmed reduction, hydrogen chemisorption and X-ray photoelectron spectroscopy measurements. The 1,3-butadiene hydrogenation was used as a model reaction. The Pd Ce interaction affected the reduction behavior of the catalysts. Temperature-programmed reduction (TPR) results showed that the presence of CeO 2 shifts the reduction temperature of PdO to lower values, while palladium similarly facilitates the reduction of the cerium surface species. The hydrogen uptake decreased when increasing the ceria content. XPS results showed that the Pd/Al ratio decreased with CeO 2 addition being affected by the preparation method and content. The formation of catalytic sites at the interface of Pd Ce was postulated from turnover frequency (TOF) results of the 1,3-butadiene hydrogenation. The number of these new sites increases with the addition of ceria. The nature of these sites is discussed in terms of the influence on the selectivity in butadiene hydrogenation.