Showing papers by "Federal University of Rio de Janeiro published in 1979"
01 Jan 1979
259 citations
TL;DR: In this paper, the existence and uniqueness of regular solutions for the Cauchy problem for the evolution equation u″ + A 2 u + (α + M(¦A 1 2 u¦ 2 ) Au = 0, suggested by the study of beams and plates, was proved.
125 citations
TL;DR: Combining boundary layer theory and experimental data for the pressure distribution and boundary layer thickness over the surface of a sphere, the following expression was obtained for the drag coefficient: C D = 1+ 9.06 R e 1 2 2 Using this formula as a basis, an expression was developed for relating the settling velocity of spherical particles to their diameter at any value of the Reynolds Number as mentioned in this paper.
119 citations
TL;DR: In this paper, a new model of grain boundary failure for intergranular fracture modes is developed based on the experimentally proved equivalence of free surface and bulk interface chemical reactions.
90 citations
TL;DR: Visually driven units, isolated in the ventrolateral group -- Pv1g and in subnucleus Pmu of the pulvinar of the cebus monkey, were studied in acute and chronic preparations under nitrous oxide N2O/O2 anesthesia during periods of EEG arousal.
81 citations
TL;DR: The major component of the trail pheromone of the South American leaf-cutting ant, Atta sexdens rubropilosa Forel, is 3-ethyl-2,5-dimethylpyrazine, and methyl and ethyl phenylacetate and methyl 4-methylpyrrole-2-carboxylate were identified and may be minor components.
Abstract: The major component of the trail pheromone of the South American leaf-cutting ant,Atta sexdens rubropilosa Forel, is 3-ethyl-2,5-dimethylpyrazine (II). Methyl and ethyl phenylacetate and methyl 4-methylpyrrole-2-carboxylate (I), which is the major component of the trail pheromone ofA. texana (Buckley) andA. cephalotes (L.), were also identified and may be minor components. The pheromone is stored in the poison gland.Atta sexdens sexdens (L.) also responds strongly to the pyrazine, which in large amounts evokes a weak response fromA. texana, A. cephalotes, andAcromyrmex octospinosus (Reich). Foraging workers ofAtta sexdens rubropilosa did not preferentially pick up baits impregnated with the pyrazine. The pyrazine was puffed into the nests ofA. cephalotes, and a particular response called “milling” was noted.
77 citations
75 citations
TL;DR: Addition of β-lapachone, an o -naphthoquinone endowed with antitumor properties for Sarcoma 180 cells, induced the formation of a semiquinone radical, which stimulated lipid peroxidation and resulted in a decrease in the viability of the cells.
73 citations
01 Jan 1979
66 citations
TL;DR: The distribution of ganglion cells in the opossum's retina was determined from flat‐mounted preparations stained with cresyl‐violet.
Abstract: The distribution of ganglion cells in the opossum's retina was determined from flat-mounted preparations stained with cresyl-violet The retinal area is 109 mm2 (SD = 16 mm2) Maps of ganglion cell density were made from retinae of seven animals In all maps iso-density lines were approximately concentric, showing a slight elongation towards the nasal region Cell density varied from 400 cells/mm2 at the extreme periphery to 2,900 cells/mm2 in the region of highest count, the are centralis The center of this region lies 185 mm (263 degree) temporal to the center of the optic nerve head The average total number of ganglion cells is 77,384 (SD = 10,173) Based upon soma diameter histograms ganglion cells were classified into three groups, showing at area centralis peaks at 7 micrometer, 12 micrometer and 15 micrometer respectively Cell soma diameter ranged from 6 micrometer to 21 micrometer, larger values being observed at the periphery
55 citations
TL;DR: In this article, an equation for the settling velocity of a suspension of spheres was developed based on a previous work by the authors, and the final equation was tested against experimental results of numerous investigators giving a mean square deviation of 0.0010.
TL;DR: In this paper, the Mossbauer effect and X-ray diffraction measurements have shown that thin lamellae of the Cape York and Toluca meteorites contain the ordered phase Fe-Ni (50-50%) with the structure L10.
Abstract: MOSSBAUER effect and X-ray diffraction measurements have shown that thin lamellae of the Cape York and Toluca meteorites contain the ordered phase Fe–Ni (50–50%) with the structure L10 (refs 1–3). The bulk of these meteorites consists mainly of body centred cubic (b.c.c.) iron–nickel α-phase alloy. We report here Mossbauer spectra, electron microprobes and X-ray measurements which show that in contrast to this, the bulk of the Ni-rich (≈35%) Santa Catharina Ataxite consists of up to 50% Fe–Ni superstructure4.
TL;DR: The extent of the retinal visual field was determined and the resulting cyclopic field established and the position of the blind and optic axes in space were indirectly determined by correlating the posture of the head under experimental and normal conditions.
TL;DR: The stimuli associated with copulation evoke disinhibition of the penile reflexes, these showing the short reflex latencies observed in the spinal animal, and tonic inhibition of reflex intensity in the normal rat is suggested.
TL;DR: In this article, the structures of soluble and insoluble glucans from isolated cell walls of yeast, mycelial, and conidial forms of Sporothrix schenckii were compared.
TL;DR: A positive correlation was observed between PMD and sex hormone intake and vaginal bleeding in the first trimester of pregnancy and a similar pattern for symmetry, sidedness, syndactyly type, and sex ratio was observed.
Abstract: Pectoralis major muscle defect (PMD) was diagnosed in 27 infants from a series of 599,109 live births in South America (1/22,189). In all 27 cases the PMD was unilateral, mainly affecting the right side (20/27), and there were more male (19/27) than female cases. No familial cases and no parental consanguinity were recorded. A positive correlation was observed between PMD and sex hormone intake and vaginal bleeding in the first trimester of pregnancy. In 12 (1/49,925) of the 27 PMD cases hypoplasia and/or syndactyly of the ipsilateral hand was also diagnosed. The index-middle interdigital space was affected in all 11 cases with symbrachydactyly. Additional congenital anomalies were observed in 4/27 cases, and they were: hemangiomas, hypospadias, and clubfeet. Poland complex (12 cases), isolated PMD (15 cases), and isolated symbrachydactyly (18 cases), showed a similar pattern for symmetry, sidedness, syndactyly type, and sex ratio.
TL;DR: In this article, an approximate method using Lyapunov functions was used to obtain a transient stability risk index which was useful in initial system planning and design studies. But the approach was limited to single and multi-machine systems and the effect of system load on the risk index was not discussed.
Abstract: Power-system transient-stability evaluation deals with the performance of the system when subjected to aperiodic disturbances such as faults, sudden loss of load or generation, and line switching. Under these conditions stability is lost when one or more generators fall out of synchronism with the rest of the system. Numerous disturbances can lead to system instability and the probabilities of their occurrences are quite different. Most system-design criteria require system survival under specific fault conditions in the normal system state. Systems are therefore designed with a set of severe criteria which may be extremely unlikely. In some cases the initial criteria become too expensive to maintain and they are modified or relaxed. The probabilities of occurrences of the disturbances should be included in the assessment to develop a realistic appraisal of system adequacy. Probabilistic considerations in the stability of simple single and multi-machine systems involves simulating the system dynamics during the disturbance. In large-scale systems, such a simulation can be computationally expensive. Approximate methods of stability evaluation are quite adequate in initial system planning to identify the critical areas. This paper deals with an approximate method using Lyapunov functions to obtain a transient stability risk index which is useful in initial system planning and design studies. The procedure for considering the probabilities associated with the type, location, and clearance of faults is illustrated for a simple multimachine system. The effect of system load on the risk index is also demonstrated.
TL;DR: The results lead to the extablishment of objective criteria to validate intracellular recordings from macrophage and show that slow membrane hyperpolarizations are directly elicited by mechanical stimulation.
TL;DR: The ATPase of the sarcoplasmic reticulum is phosphorylated by ATP in the presence of Ca2+.
TL;DR: In this paper, the authors relax the classical assumption that all the interactions are negligible by assuming that (at most) one of them may be nonnegligible, and discuss designs which allow the search and estimation of this interaction, along with the estimation of the general mean and the main effects.
TL;DR: It is suggested that a fraction of ATPase units of dystrophic sarcoplasmic reticulum is not activated by Ca2+, owing to an altered protein assembly within the membrane bilayer.
TL;DR: The results suggest that unless the near‐UV damaged phage DNA is repaired immediately after injection, the lesions rapidly lose their susceptibility to repair with a consequent loss of activity of the phage particles.
Abstract: Intact bacteriophage have been irradiated at 365 nm or at 254 nm and then analysed for DNA photoproducts or injected into their bacterial host to test susceptibility of the damage to both phage and host-cell mediated repair systems. Both thymine dimers and single-strand breaks are induced in the phage DNA by 365 nm radiation. The dimers appear to be the major lethal lesion (approximately 2 dimers per lethal event) in both repair deficient bacteriophage T4 and bacteriophage λ. after irradiation with either 254 nm or 365 nm radiation. Damage induced in T4 by either wavelength is equally susceptible to x-gene reactivation (repair sector approximately 0.5). v-gene reactivation acts on a larger fraction of the near-UV damage (repair sector of 0.82 at 365 nm as against 0.66 at 254 nm). The host-cell mediated photoreactivation system is only slightly less effective for near-UV damage but host-cell reactivation (as measured by comparing survival of phage λ. on a uvr+ and a uvr- host) is effective against a far smaller sector of near-UV damage (0.35) than far-UV damage (0.85). Weigle-reactivation (far-UV induced) of near-UV damage to phage λ is not observed. The results suggest that unless the near-UV damaged phage DNA is repaired immediately after injection. the lesions rapidly lose their susceptibility to repair with a consequent loss of activity of the phage particles.
TL;DR: Yeast walls had higher contents of total carbohydrate, mainly water- and alkali-soluble polysaccharides, and lower contents of proteins and lipids, while mycelial and conidial walls were qualitatively and quantitatively similar.
TL;DR: In this paper, the authors identified the most prominant lines in LiAl 5 O 8 :Cr and showed that a number of them are zero phonon lines due to Cr 3+ in inequivalent octahedral sites.
TL;DR: In this article, the process of temper embrittlement provoked by impurity (P, S) segregation in a high alloy Cr, Ni steel is studied by means of Auger electron spectroscopy (AES) and ionization loss spectrography (ILS).
TL;DR: The effects of nondeterminism and of other logics on the family of languages accepted, comparison with finite automata in terms of number of states and a bound on a decision procedure are presented.
Journal Article•
TL;DR: It is concluded that dose‐dependent damage to DNA repair by the near‐UV radiation is involved in the interaction and possibly that MMS causes irreversible damage 10 repair enzymes.
Abstract: — The lethal interaction between monochromatic radiation at various wavelengths and methyl methane sulphonate was tested in strains of Escherichia coli proficient and deficient in DNA repair. In the repair proficient wild-type strain K12 AB1157, the efficiency of sensitization to MMS as a function of dose (at 334 nm, 365 nm and 405 nm) was found to be directly correlated with the dose necessary to remove the shoulder from the survival curve at the wavelength employed. The 365 nm: MMS interaction was also observed in other repair proficient E. coli strains (W3110 and B/r) but was absent in a recA and a polA strain. Pre-treatment of AB1157 with MMS leads to a much larger interaction than pre-irradiation with 365 nm. It is concluded that dose-dependent damage to DNA repair by the near-UV radiation is involved in the interaction and possibly that MMS causes irreversible damage 10 repair enzymes.
TL;DR: In this article, a semiclassical method to determine the contribution to the optical potential in the elastic channel due to the coupling to other processes taking place in heavy-ion collisions is developed.