Showing papers by "State University of Campinas published in 1990"
Journal Article•
TL;DR: Insulin resistance, high blood glucose level, impairment of cardiac response and hyperinsulinemia are present in a significant portion of hypertensive patients.
Abstract: To determine the possible existence of a relationship between insulin resistance and sympathetic nervous system activity in essential hypertension, we calculated the double cross index for 14 hypertensive subjects and 14 normotensive subjects submitted to the oral glucose test. Plasma glucose and insulin levels were similar in hypertensive and normotensive subjects. After glucose loading, however, both parameters were significantly higher in hypertensive subjects. Five out of 14 hypertensive patients were hyperinsulinemic. The increase in double cross index following a glucose load was significantly higher in normotensive volunteers than in hyperinsulinemic hypertensive subjects. No change in double cross index was observed in normoinsulinemic hypertensive subjects. Thus, insulin resistance, high blood glucose level, impairment of cardiac response and hyperinsulinemia are present in a significant portion of hypertensive patients. Hyperinsulinemia may contribute to hypertension by stimulating sympathetic nervous system activity, by influencing the calcium transport across the cell membrane and/or by some other mechanism.
753 citations
TL;DR: It is concluded that the perturbation of the inner mitochondrial membrane caused by Ca2+ plus prooxidants is associated with protein polymerization due to thiol cross-linking, resulting in the production of high molecular mass protein aggregates.
187 citations
TL;DR: Three piranha species seem to strongly influence use of habitat, social structure, and foraging mode of the fish communities, and defensive tactics of prey fishes were observed.
Abstract: The behaviour of three piranha species,Serrasalmus marginatus, S. spilopleura, andPygocentrus nattereri, and their prey fishes was studied underwater in the Pantanal region, Mato Grosso, Brazil. General habits, predatory tactics, feeding behaviour, and social interactions while foraging, as well as defensive tactics of prey fishes were observed.S. marginatus is solitary whereas the other two species live in shoals; their agonistic behaviour varies accordingly, the simplest being displayed by the solitary species. Predatory tactics and feeding behaviour also vary:S. spilopleura shows the most varied diet and highly opportunistic feeding strategy, which includes aggressive mimicry. The solitaryS. marginatus, besides fin and scale-eating, occasionally cleans larger individuals ofP. nattereri. Several cichlid species display defensive tactics clearly related to piranha attacks: tail protecting, watching, and confronting the predator are the most commonly observed behaviours. Piranhas seem to strongly influence use of habitat, social structure, and foraging mode of the fish communities.
140 citations
TL;DR: Using two different photoacoustic techniques for a two-layer system of variable thickness, the thermal diffusivity and the thermal conductivity are completely determined, based upon the effective-sample model widely used in heat transfer problems as discussed by the authors.
Abstract: Using two different photoacoustic techniques for a two-layer system of variable thickness, we show that the thermal diffusivity and the thermal conductivity are completely determined, based upon the effective-sample model widely used in heat-transfer problems. A procedure to establish a standard photothermal technique for measuring both the thermal diffusivity and the thermal conductivity is also discussed.
127 citations
25 Oct 1990
124 citations
TL;DR: In this article, a nonlinear quantum transport theory for many-body systems arbitrarily far away from equilibrium, based on the nonequilibrium statistical operator method, is discussed, and an iterative process is described that allows for the calculation of the collision operator in a series of instantaneous in time partial contributions of ever increasing power in the interaction strengths.
Abstract: A nonlinear quantum transport theory for many-body systems arbitrarily far away from equilibrium, based on the nonequilibrium statistical operator method, is discussed. An iterative process is described that allows for the calculation of the collision operator in a series of instantaneous in time partial contributions of ever increasing power in the interaction strengths. These partial collision operators are shown to be composed of three contributions to the dissipative processes: one is a direct result of the collisions, another is accounted for in the internal state variables, and the third arises from memory effects. In the lowest order, the so-called linear theory of relaxation, the equations become Markovian.
119 citations
TL;DR: Dans l'intervalle des frequences ou l'echantillon est thermiquement epais, l'amplitude du signal and the phase peuvent differencier les sources de chaleur de recombinaison non radiative rapide and lente responsables du signal photo acoustique.
Abstract: The photoacoustic signal of two semiconductor samples is investigated as a function of the modulation frequency in a heat-transmission configuration. It is shown that, in the frequency range where the sample is thermally thick, the signal amplitude and phase can single out the different fast and slow nonradiative recombination heat sources responsible for the photoacoustic signal. The characterization of the thermal and the carrier transport properties is discussed and some practical procedures for this purpose are also outlined.
108 citations
TL;DR: In this paper, the saponification step in the determination of carotenoids was reassessed and the AOAC procedure, performed in the presence of acetone, led to complete transformation of β-apo-8′-carotenal to citranaxanthin.
107 citations
TL;DR: In this paper, the authors describe the combined heat and mass-transfer natural convection mechanisms, which are considered an important subfield in contemporary heat andmass transfer research, and consider the phenomena of convection through fluid-saturated porous media generally in terms of volume-averaged quantities.
Abstract: Publisher Summary The chapter describes the combined heat and mass-transfer natural convection mechanisms, which are considered an important subfield in contemporary heat and mass-transfer research. This subfield essentially brings together the studies concerned with the combined heat and mass-transfer or double-diffusive processes that are driven by buoyancy through porous media saturated with fluid. The density gradients that provide the driving buoyancy effect are induced by the combined effects of temperature and species concentration nonuniformities present in the porous medium. The chapter considers the phenomena of convection through fluid-saturated porous media generally in terms of volume-averaged quantities. There are four conservation principles considered in the study of convection with more than one buoyancy effect. These include conservation of mass, energy, species, and momentum. Heat and mass transfer in the vertical direction and in horizontal direction are discussed in detail. Another category of studies of combined buoyancy effects in porous media deals with the local fields around buried sources of heat and mass. The recent work in this field focuses on the multilayer structure of flows of the boundary-layer or concentrated-source type.
104 citations
TL;DR: This work describes the qualitative behavior of generic discontinuous vector fields around a point p ∈ R 3 and shows how these fields change over time.
101 citations
TL;DR: This approach avoids the necessity of very large Gaussian basis sets, allowing the size of the basis to reflect only the dynamical requirements of the scattering wave function and results in improved efficiency, in spite of the additional numerical effort of performing the quadrature.
Abstract: We discuss some recent developments in the implementation of the Schwinger multichannel method for electron-molecule collision calculations. The evaluation of matrix elements involving the operator VG^(+)_PV, previously accomplished by insertion of a Gaussian basis on either side of G^(+)_P, is now done by direct numerical quadrature. This approach avoids the necessity of very large Gaussian basis sets, allowing the size of the basis to reflect only the dynamical requirements of the scattering wave function. We find that the reduction in the required basis size results in improved efficiency, in spite of the additional numerical effort of performing the quadrature. Trial applications to electron-CH4 scattering in the static-exchange approximation and to electronic excitation of H_2 illustrate the excellent convergence characteristics of the procedure.
TL;DR: The thermal biology and flight distance of the tropical lizard Tropidurus oreadicus was studied on iron ore outcrops at Serra dos Carajas, in Brazilian Amazonia and suggested that the importance of rocks as basking sites changes during the morning due to the angle of the sun.
Abstract: The thermal biology and flight distance of the tropical lizard Tropidurus oreadicus was studied on iron ore outcrops (called canga) at Serra dos Carajas, in Brazilian Amazonia. Body temperature varied markedly throughout the day (range 32.0 to 38.1 °C), but mean preferred body temperature was 35.8 °C. The air temperature in the microhabitat explained a considerable part of Tropidurus oreadicus body temperature variation, but other factors such as direct insolation and substratum teperature may also be of importance. In the morning, lizards usually climbed onto rocks and assumed progressively changing body orientations and inclinations which increased the interception of sunlight. Later they retreated to vegetation. This suggested that the importance of rocks as basking sites changes during the morning due to the angle of the sun. The flight distance was greater when body temperature was low and this may be of survival value in open areas such as the mineral outcrops of Serra dos Carajas.
TL;DR: In this paper, an intensive study was made of a gallery forest near Cuiaba, State of Mato Grosso, Brazil, where the vegetation on 67 plots of 30 m 2 demonstrated a great deal of heterogeneity related principally to differences in topography and drainage.
TL;DR: In this paper, the applicability of the Nonequilibrium Statistical Operator Method (NSOM) for the study of dissipative dynamic systems far from equilibrium is discussed, which can be encompassed by a unifying variational principle, which produces a large family of NSO that contains existing examples as particular cases.
Abstract: We describe the large applicability of the Nonequilibrium Statistical Operator Method (NSOM) for the study of dissipative dynamic systems far from equilibrium. It is shown that the NSOM can be encompassed by a unifying variational principle, which produces a large family of NSO that contains existing examples as particular cases. Further, we review the application of the NSOM for the construction of a nonlinear quantum theory of large scope, and for the generation of a response function theory, for far-from-equilibrium Hamiltonian systems. An accompanying non-equilibrium thermodynamic Green's function theory is briefly described. Also it is shown that the NSOM provides mechano-statistical foundations for phenomenological irreversible thermodynamics, and for the important question of stability of far-from-equilibrium steady states and the emergence of self-organized dissipative structures in condensed matter.
01 Jan 1990
TL;DR: In this article, sufficient conditions for the validity of the maximum principle for cooperative and non-cooperative elliptic systems are given. But these conditions are not applicable to non-collaborative systems.
Abstract: In this paper we obtain some sufficient (necessary) conditionsfor the validity of the maximum principle for cooperative and non-cooperative elliptic systems.
TL;DR: Women using continuous low-dose levonorgestrel contraception through NORPLANT subdermal implants, have a variable degree of ovarian activity as compared with the more complete depression of ovarian function observed among pill or injectables' users.
TL;DR: Bothrops insularis snake venom was fractionated by gel filtration on Sephadex G-150 followed by ion-exchange chromatography on SP-SephadeX C-25 and none of the five isolated fractions showed any proteolytic (on casein) or kininogenase activity.
TL;DR: Caracterisation du compose par XPS, spectrometrie de perte d'energie electronique et absorption optique, Analyse de the possibilite d'une segregation en silicium pur et nitrure desilicium stoechiometrique.
Abstract: We present a study of amorphous hydrogenated silicon-nitrogen alloys (a-${\mathrm{SiN}}_{\mathit{x}}$:H, 0\ensuremath{\le}x1.5) prepared by the rf reactive sputtering method. By combining results of x-ray photoemission spectroscopy, electron-energy-loss spectroscopy, and optical absorption, all the atom and bond densities and the kind and mean number of nearest neighbors of Si and N atoms are determined. For x1, Si-N bonds increase at the expense of Si-Si bonds; N atoms are almost fully coordinated by three Si atoms, whereas Si atoms have N, H, and other Si atoms as nearest neighbors. For xg1, Si-N bonds increase at the expense of both Si-Si and Si-H bonds; however, this is not enough to saturate the three N valencies with Si and some N-H and possibly N-N bonds begin to appear. The opening of the optical gap occurs at x\ensuremath{\simeq}1.1 when the ratio of the densities of Si-Si bonds to Si-N bonds has fallen below 0.10. Near stoichiometry, substantial amounts of Si-Si and N-H bonds are observed. The possibility of segregation into pure silicon and stoichiometric silicon nitride is discussed by analyzing the Si 2p line shape. A linear relationship between the Si 2p chemical shift and the mean number of N-atom nearest neighbors of Si is observed; a charge transfer of 0.35e per Si-N bond is determined.
TL;DR: An anatomical study made in 25 injected fresh subjects made it possible to map out the periosteal flaps capable of being raised on the limbs, and the preferred donor sites are the distal third of the humerus, the iliac fossa and the distals of the femur.
Abstract: An anatomical study made in 25 injected fresh subjects made it possible to map out the periosteal flaps capable of being raised on the limbs The preferred donor sites are the distal third of the humerus, the iliac fossa and the distal third of the femur At the last 2 sites composite osteo-periosteal or musculo-osteo-periosteal flaps can be raised These technical possibilities illustrate the importance of experimental studies which have shown the osteogenic capacity of grafts of vascularized periosteum
TL;DR: The ultrasonographic findings of these unusual pediatric masses are described and correlated with their conventional radiologic and pathologic appearance and the pre-operative diagnosis of these entities can be suggested by these features.
Abstract: Four children with benign intraperitoneal lipomatous tumors (mesenteric lipoma, mesenteric lipoblastoma, omental lipoblastoma and mesenteric mesenchymoma) are reported. The ultrasonographic findings of these unusual pediatric masses are described and correlated with their conventional radiologic and pathologic appearance. The pre-operative diagnosis of these entities can be suggested by these features.
TL;DR: In this article, the group-theoretic equivalence of covariant and algebraic spinors was shown for p+q ≥ 5 and for p + q ≥ 5.
Abstract: We deal with three different definitions for spinors: (I) thecovariant definition, where a particular kind ofcovariant spinor (c-spinor) is a set of complex variables defined by its transformations under a particular spin group; (II) theideal definition, where a particular kind of algebraic spinor (e-spinor) is defined as an element of a lateral ideal defined by the idempotente in an appropriated real Clifford algebra ℝ
p,q
(whene is primitive we writea-spinor instead ofe-spinor); (III) the operator definition where a particular kind of operator spinor (o-spinor) is a Clifford number in an appropriate Clifford algebra ℝ
p,q
determining a set of tensors by bilinear mappings. By introducing the concept of “spinorial metric” in the space of minimal ideals ofa-spinors, we prove that forp+q≤5 there exists an equivalence from the group-theoretic point of view among covariant and algebraic spinors. We also study in which senseo-spinors are equivalent toc-spinors. Our approach contain the following important physical cases: Pauli, Dirac, Majorana, dotted, and undotted two-component spinors (Weyl spinors). Moreover, the explicit representation of thesec-spinors asa-spinors permits us to obtain a new approach for the spinor structure of space-time and to represent Dirac and Maxwell equations in the Clifford and spin-Clifford bundles over space-time.
15 Oct 1990
TL;DR: Etude des energies de liaison and de la densite d'etat des impuretes en fonction de the position of l'impurete, de l'epaisseur des puits, and du champ electrique applique.
Abstract: The influence of an applied electric field on shallow donor and acceptor states in GaAs-(Ga,Al)As quantum wells is studied. We work within the effective-mass approximation and adopt a trial envelope wave function for the impurity carrier, which leads to the exact results for vanishing applied electric fields and limiting values of the quantum-well thickness. Results for the binding energies and density of impurity states as functions of the impurity position, well thicknesses, and applied electric field are reported. Some results for the effects of electric field on the donor-related optical properties are also presented. As a general feature, the density of impurity states and impurity-related optical absorption for finite electric fields exhibit three van Hove--like singularities corresponding to the binding energies associated with impurities at the two edges of the quantum well and at the position at which the binding energy has a maximum.
TL;DR: The association of balloon dilation and incision by special endoureterotomy scissors is a potentially useful technique in the treatment of ureteral stricture disease.
TL;DR: The pollination biology and breeding systems ofKielmeyera coriacea andK.
Abstract: The pollination biology and breeding systems ofKielmeyera coriacea andK. speciosa, two sympatric woody species common in the cerrado vegetation of C. Brazil, were studied. Both species have similar nectarless, polystemonous “Papaver-type” flowers which are visited by a similar spectrum of insects, though they bloom in different seasons and are thus phenologically isolated. Large carpenter bees seem to be the most important pollinators and these and other bees effect “buzz pollen” retrieval despite the fact that anthers are not poricidal. Both species ofKielmeyera possess strong xenogamous breeding systems. The presence of staminate flowers and andromonoecy inK. coriacea, as well as the longevity ofK. speciosa flowers are discussed as alternative strategies to improve pollination success and reproductive efficacy.
TL;DR: It was observed that the Ltr ∗ 1 gene intensified the effect of the o2 gene on amino acid and protein synthesis in maize endosperm.
TL;DR: Little variation in PA content was found among allopatric populations of the same species, but variation in available PA sources in different months was correlated with different average storage levels in the butterflies.
Abstract: The primitive, Apocynaceae-feeding Ithomiine,Tithorea harmonia, incorporates dehydropyrrolizidine alkaloids (PAs) from its larval foodplant (Prestonia acutifolia), rarely visiting PA sources pharmacophagously in the adult; females show higher concentrations of PAs than males, with similar variance. The close relativeAeria olena (feeding onP. coalita, without PAs) shows similar PA concentrations in both sexes and greater variation in males, like more advanced Solanaceae-feeding Ithomiine such asMechanitis polymnia, which likeA. olena obtain PAs by pharmacophagy in the adult (mainly males). This difference is due to the dynamics of PA incorporation in these species. Little variation in PA content was found among allopatric populations of the same species, but variation in available PA sources in different months was correlated with different average storage levels in the butterflies.
TL;DR: In this article, the chemically modified silica, obtained by reacting 2-mercaptobenz-imidazole with 3-chloropropyl silica gel, was used to adsorb Cu(II), Zn (II), Cd(II) and Pb(II).
Abstract: The chemically modified silica, obtained by reacting 2-mercaptobenz-imidazole with 3-chloropropyl silica gel, was used to adsorb Cu(II), Zn(II), Cd(II) and Pb(II) from aqueous solutions at various pH. Between pH 3–5, the order of selectivity was Hg(II) > Cd(II) ≫ Cu(II) ∼ Zn(II) ∼ Pb(II). Under batch conditions retentions of 100% were achieved for all metals except for Pb(II) where 93% was attained. Under column conditions recoveries of 100% were obtained for all metals.
TL;DR: The results suggest that the oedema induced by polycations was due to their cationic charge rather than a decrease in vascular permeability.
Abstract: 1. The inflammatory response induced by poly-L-arginine in the rat hind-paw was studied both by measuring paw oedema and histologically. 2. The paw volume was measured with a hydroplethysmometer at 0.5, 1, 2, 4, 6 and 18 h after the subplantar injection of the polycation. Protein extravasation was evaluated with Evans' blue and the histology studied by light microscopy. 3. Poly-L-arginine (12, 24, 43 and 115kD) caused dose- and molecular weight-dependent oedema which had a rapid onset and long duration. Evans' blue extravasation paralleled the oedema induced by poly-L-arginine. Microscopic examination of the paws at early stages of oedema formation showed exuberant liquid exudate with no inflammatory cells. After 18 h, a cellular infiltrate was present, consisting mainly of mononuclear cells. 4. Indomethacin, dexamethasone, BW755c or the PAF-antagonist WEB 2086 caused no significant inhibition of the poly-L-arginine-induced oedema. Cyproheptadine had inhibitory effects only on the early stages of the polycation-induced oedema. Similar results were observed with rats depleted of histamine and 5-hydroxytryptamine. 5. Heparin, a polyanion, injected in the rat paw caused a marked inhibition of the polycation-induced oedema. NG-monomethyl-L-arginine (LNMMA), an inhibitor of EDRF synthesis, injected locally also produced a marked inhibition, but this inhibition was reversed by iloprost. 6. These results suggest that the oedema induced by polycations was due to their cationic charge. The inhibitory effect of LNMMA is probably due to a decrease in vascular flow rather than a decrease in vascular permeability.
TL;DR: Inhibition in the respiration of E. coli suspensions were detected within 20 min for Hg(II) ions and the antibiotic, whereas sediment samples from eutrophic water bodies stimulated CO 2 production.