Showing papers by "Federal University of Rio de Janeiro published in 1976"
TL;DR: The elastic system of normal human skin was studied by light and electron microscopy and found that in the elaunin fibers the amorphous material is sparse, while in the elastic fibers it is abundant and compact.
302 citations
TL;DR: In this paper, it was shown that as t → ∞ the corresponding limit of the consumption policy is strictly bounded above by the expected value of the random income, and that no borrowing is allowed, and for the amounts saved no interest is paid.
137 citations
TL;DR: Fixation with tannic acid-glutaraldehyde permits distinction of oxytalan, elaunin and elastic fibers in the electron microscope and is recommended for studying fine details of connective fibrils and for regular staining of elastin.
Abstract: Fixation with tannic acid—glutaraldehyde permits distinction of oxytalan, elaunin and elastic fibers in the electron microscope. The results obtained using tannic acid at concentrations of 1.0%, 0.5% and 0.25% in 3% glutaraldehyde were compared. The 0.25% concentration is recommended for studying fine details of connective fibrils and for regular staining of elastin.
130 citations
TL;DR: It is suggested that the sensitisation to X‐rays seen in the HeLa cells after 365 nm treatment is not the result of lesions induced in DNA by the near‐UV radiation, but may reflect the disruption of DNA‐repair systems.
Abstract: — The colony-forming ability of Chinese hamster cells (V-79) and HeLa cells has been measured after near-ultraviolet (UV) irradiation, predominantly at 365 nm. To avoid the production of toxic photoproducts, cells were irradiated in an inorganic buffer rather than in tissue culture medium. Under these circumstances near-UV lethality was strongly oxygen-dependent. Both cell lines were approximately 104 times more sensitive to 254 nm irradiation than to 365 nm radiation when irradiated aerobically. Pretreatment with 6 times 105 Jm-2 365 nm radiation sensitised the HeLa, but not the V-79 cell line to subsequent X-irradiation. Pretreatment of cells with 17 Jm-2 254 nm radiation, a dose calculated to produce twenty times more pyrimidine dimers than the 365 nm dose, produced only slight sensitisa-tion to X-rays. It is suggested that the sensitisation to X-rays seen in the HeLa cells after 365 nm treatment is not the result of lesions induced in DNA by the near-UV radiation, but may reflect the disruption of DNA-repair systems.
121 citations
TL;DR: Investigation of diterpenoids in four species of Pterodactylus showed varying oxidation patterns on the vinhaticane or vouacapane skeletons as discussed by the authors.
64 citations
TL;DR: In this article, it is shown that if a linear dynamic system is to provide observer action despite arbitrary small perturbations in a specified subset of its parameters, it must 1) be a closed-loop system, i.e., be driven by the observer error, 2) possess redundancy, and 3) contain a perturbation-free model of the portion of the system observable from the external input to the observer.
Abstract: In this short paper conventional observers for linear time-invariant systems are shown to be structurally inadequate from a sensitivity standpoint. It is proved that if a linear dynamic system is to provide observer action despite arbitrary small perturbations in a specified subset of its parameters, it must 1) be a closed-loop system, i.e., be driven by the observer error, 2) possess redundancy, i.e., the observer must be generating, implicitly or explicitly, at least one linear combination of states that is already contained in the measurements, and 3) contain a perturbation-free model of the portion of the system observable from the external input to the observer. The procedure for design of "robust" observers possessing the above structural features is established and discussed.
55 citations
TL;DR: A new backtracking algorithm is proposed which is bounded byO(N +M(C + 1) time, for a directed graph withN vertices,M edges andC elementary cycles.
Abstract: The most successful known algorithms enumerating the elementary cycles of a directed graph are based on a backtracking strategy. Such existing algorithms are discussed and a new backtracking algorithm is proposed which is bounded byO(N +M(C + 1)) time, for a directed graph withN vertices,M edges andC elementary cycles.
48 citations
TL;DR: It is proposed that in addition to DNA damage, both heat treatment and near ultraviolet treatment interfere with DNA recovery mechanisms so that the combination of the two agents inevitably leads to a strong positive interaction.
Abstract: — The lethal interaction of far ultraviolet (254nm), near ultraviolet (334 and 365nm) and violet visible (405nm) radiation treatment with mild heat treatment was studied. Except at 254nm, a strong positive radiation dose-dependent interaction (synergism) was always observed. The efficiency of sensitisation to heat, as a function of dose at each wavelength, was found to be directly correlated with the dose necessary to eliminate the shoulder from the survival curve of a repair proficient strain but was apparently unrelated to the relative near-ultraviolet sensitivities of a repair deficient strain. The interaction was independent of the order of treatments. A radiation dose of 106 Jm-2 at 365nm slightly sensitised a cell population to 45°C incubation (normally non-lethal) and strongly sensitised the cells to 48°C treatment (normally 80 percent survival after 2 hours). It is proposed that in addition to DNA damage, both heat treatment and near ultraviolet treatment interfere with DNA recovery mechanisms so that the combination of the two agents inevitably leads to a strong positive interaction.
47 citations
TL;DR: Through the radioautographic technique of axon tracing, it was demonstrated that the accessory optic system follows the generalized scheme of Hayhow, consisting of two fascicles the three terminal nuclei.
37 citations
TL;DR: In this article, the root bark of Derris obtusa has been identified and two 3-O -methylauronols have been found in nature, called Derriobtusones A and B. Structures were established through chemical and spectral means, and mass spectral fragmentation schemes were suggested for aurones and auronols.
37 citations
TL;DR: The general ultrastructure of the electrocyte, the basic unit of the electric organs of Electrophorus electricus, is analyzed and detailed observations of the syncytial surface, its fibrillar coat, invaginations of the plasma membrane and synaptic terminals are presented.
Abstract: The general ultrastructure of the electrocyte, the basic unit of the electric organs of Electrophorus electricus, is analyzed. Presented herein are detailed observations of the syncytial surface, its fibrillar coat, invaginations of the plasma membrane and synaptic terminals. Using Thiery's method glycogen granules were identified in the syncytial cytoplasm and inside the synaptic terminals, their size and structure being compatible with the muscular origin of the electric organs, to which the filamentous meshwork found in the cytoplasm may be related. Among the perinuclear-organelles, are dense bodies with crystalline patterns. The mitochondrial matrix contains dense granules, their size and structure varying according to the organ to which they belong and to the fixation method used.
TL;DR: It is proposed that striate receptive fields in the opossum have a similar organization to those of other mammals.
TL;DR: Biological evidence indicated that stationary phase cells had not lost the capacity for photo-enzymatic repair after fluences of 365-nm radiation of 2 X 10(6) J/m-2 or less and it is proposed that pyrimidine dimers, although induced, are not significant 365- nm lethal lesions in uvrA and wild-type strains because of their efficient dark repair.
Abstract: Photoreactivation (PR) after 365-nm inactivation was measured in four strains of Escherichia coli differing in repair capability. Photoreactivation was observed in the recA strains K12 and AB2480 and K12 AB2463 indicating a significant role of pyrimide dimers in the lethal action of 365-nm radiation in these strains. Significant PR was not observed in the uvrA strain, K12 AB1886, or in the repair proficient strain, K12 AB1157, after 265-nm inactivation. Biological evidence indicated that stationary phase cells had not lost the capacity for photo-enzymatic repair after fluences of 365-nm radiation of 2 × 106 J/m−2 or less. It is proposed that pyrimidine dimers, although induced, are not significant 365-nm lethal lesions in uvrA and wild-type strains because of their efficient dark repair.
TL;DR: Attention is called to the possibility of human cases of infection, namely visceral larva migrans although no cases have been reported up to the present, and to the prevalence of Toxocara eggs in the soil of 24 city parks in Rio de Janeiro.
Abstract: The authors present a study on the prevalence of Toxocara eggs in the soil of 24 city parks in Rio de Janeiro; 10 of them were contaminanted by Toxocara eggs. Attention is called to the possibility of human cases of infection, namely visceral larva migrans although no cases have been reported up to the present.
TL;DR: In this paper, the optimal design of continuous one-dimensional structures driven by harmonically oscillating loads is examined. But the authors focus on a cantilever bar driven sinusoidally by an axial force at its tip to illustrate the minimum-weight design of one dimensional structures under dynamic excitation.
Abstract: The paper examines some questions relating to the optimal design of continuous one-dimensional structures driven by harmonically oscillating loads. Optimal-control methods are applied to a cantilever bar driven sinusoidally by an axial force at its tip to illustrate the minimum-weight design of one-dimensional structures under dynamic excitation. Realistic constraints are imposed during the optimizations, including a maximum allowable stress amplitude at any point along the bar and a minimum cross-sectional area. It is shown that in the absence of damping, the design space may contain many disjoint feasible regions, and multiple optima can exist. Detailed solutions are obtained for continuous bars with an excitation frequency less than, and then greater than, the fundamental free-vibration frequency. It is found that above a certain excitation frequency, two or more arcs with different constraints characterize the optimal designs. It is concluded that when more than two different constrained arcs characterize the optimal solution, the continuum approach may be impractical, and finite-element approximations may offer the only alternative.
TL;DR: It seems likely that Ca2+ can be translocated across sarcoplasmic reticulum membrane without the formation of a phosphorylated intermediate.
TL;DR: In this article, the surface composition of synthetic bornite has been studied by using Auger electron spectroscopy and the results show that it exhibits large and rapid changes which are due mainly to movement of mobile Cu + ions through the lattice.
TL;DR: In this article, an axiomatic treatment based on the notion of the power as a linear functional on the space of virtual velocity fields is presented. But the approach is restricted to the case of a single continuum, regarded as a mixture with only one constituent.
Abstract: All previous axiomatic treatments of mixture theory neglected diffusion. In particular, GURTIN & DE LA PENI-tA 1 and OLIVER 2 considered rigid mixtures while WILLIAMS 3 allowed mechanical effects, but without diffusion. The main purpose of this paper is to derive dynamical local equations for the mechanical behavior of a mixture with diffusion; the equations of energy and entropy will be treated in a future paper. 4 With this in mind, I present an axiomatic treatment based on the notion of the power as a linear functional on the space of virtual velocity fields. The norm we use in ~ rules out multipolar interactions, but it is a simple exercise to change the norm in ~ to include multipolar interactions, e.g., to include the velocity gradient. I remark, however, that in this instance one must introduce a normalization condition in order to obtain uniqueness for the force measures. The approach we use, which introduces the concept of force in a very natural manner, also applies without change to the case of a single continuum, regarded as a mixture with only one constituent. I now give a summary of this paper. In Part I I give some preliminary definitions. In Part II the power is introduced. The power will be assumed to be a biadditive, bounded linear functional on 5. With this assumption we are able to represent the power as an integral of the velocity field with respect to a certain measure, which we define to be the force. The total power for a constituent will then be assumed to have a certain invariance property which is a consequence of the principle of objectivity. This assumption will give us the balance of force and moment for a constituent. In Part I I I I introduce some additional assumptions on the force measures #. This, with some smoothness conditions, will give us the existence of a stress tensor for each component of the mixture and the existence of an interaction stress for each pair of distinct components of the mixture. I also derive local balance equations and discuss relevant boundary value problems for the mixture. The equations we get differ from the classical ones, as presented, e.g., by BOWEN. 5
TL;DR: The Equatorial Mid-Ocean Canyon as discussed by the authors is an erosional-depositional deep-sea channel which was formed by turbidity-current activity, was active during the Miocene, but is now a relict feature.
Abstract: The Equatorial Mid-Ocean Canyon is an erosional-depositional deep-sea channel which was formed by turbidity-current activity, was active during the Miocene, but is now a relict feature. The canyon parallels the Brazilian continental rise between 3°–5°S and 33°15′ to 28°W and descends eastward for at least 1,200 km with a gradient of 1:1,000. The canyon is 5 to 8 km wide and as much as 200 m deep. Although the bathymetric expression of the canyon on the sea floor begins at about 33°15′W, the canyon has been traced westward (up-slope) from this longitude in subsurface for at least 75 to 150 km. The trend of this buried portion of the canyon indicates that originally the head of the canyon was on the upper continental rise. The stratigraphic relationship between the canyon and a lower Miocene acoustic reflector of widespread regional extent suggests that the canyon formed during the late early Miocene period. Piston cores from the canyon floor, walls, and levees consist largely of pelagic foraminiferal marls and brown clays which indicate that the canyon has been inactive for at least the past million years. The exact time when the canyon became inactive is still uncertain, but it was probably middle to late Miocene. When active, the canyon channeled terrigenous sediments southeastward along the trend of the Fernando de Noronha Basin. The canyon apparently was abandoned and subsequently buried when the predominant direction of sediment dispersal shifted from southeastward along the Fernando de Noronha Basin to northeastward into the adjacent Guiana Basin, thus making the canyon path obsolete.
TL;DR: In this paper, a linear perturbation for the wave equation was considered and the scattering operator S(q) determined uniquenes uniquely the scatterer q (at least in this class).
TL;DR: In this article, Lesmes gave sufficient conditions for a subalgebra AcCm(E) to be dense in (CmE, z~), when m = l, and E is a real separable Hilbert space.
Abstract: (1) for every xE U, there exis ts fEA such t h a t f ( x ) r (2) for every pair x, yEU, with xr there exists fEA such that f(x)r (3) for every xE U and vEE, with v ~ 0 , there exists fEA such that Df(x)v~O. In [1], Lesmes gave sufficient conditions for a subalgebra AcCm(E) to be dense in (Cm(E), z~), when m = l , and E is a real separable Hilbert space. In fact, he proved that (1), (2), (3) (with U=E) and
TL;DR: In this paper, the Efimov bound states for a system of three identical spinless particles interacting in pairs through delta-shell potentials were studied, and a new family of bound states were found for higher values of the attractive coupling strength.
TL;DR: Aspidosperma cuspa Blake as mentioned in this paper contains kopsanone, epikopsanol, kopsanol and 16-epi-isositsirikine.
TL;DR: Lead concentrations in drinking water and air have been measured as mentioned in this paper, and the results showed that houses with lead inlet pipes had between 30 and 1000 μg l−1, with a mean of about 100 μg l −1.
TL;DR: Using the periodic acid-thiosemicarbazide-silver proteinate technique, a positive reaction was observed on the membranes of the Golgi complex of Leptomonas pessoai.
Abstract: Using the periodic acid-thiosemicarbazide-silver proteinate technique, a positive reaction was observed on the membranes of the Golgi complex of Leptomonas pessoai. A positive reaction was also observed in other cytoplasmic membranes located near the Golgi complex. Structures which could represent reserve polysaccharides were not observed in the cytoplasm of Leptomonas pessoai.
TL;DR: Anti-Brucella agglutinins were found in 5 of 53 (9.4%) vampire bats Desmodus rotundus, captured in the State of Bahia, Brasil, and two specimens of Diphylla ecaudata were negative.
Abstract: Anti-Brucella agglutinins were found in 5 of 53 (9.4%) vampire bats Desmodus rotundus, captured in the State of Bahia, Brasil. Two specimens of Diphylla ecaudata were negative. Fifty specimens of the small monkey, Callithrix penicillata, were also negative.
TL;DR: In this article, the isolation of 3β,20(R)-dihydroxydammer-24-ene and 20 (R)-hydroxymmar-24,en-3-one from Barbacenia bicolor Mart is described.