Showing papers by "State University of Campinas published in 1978"
TL;DR: In this paper, it was shown that for planar graphs, the lower bound on the cardinality of a feedback set of a directed graph G is equivalent to the dual lower bound of the corresponding lower bound for a transversal of directed cuts.
Abstract: This minimax equality was conjectured about a decade ago by one of the authors ([7; page 43], [8], [9]) and, independently, by Neil Robertson. It arose in the study of a problem posed several years prior to that by John Runyon [5; page 299]: for a directed graph, give an efficient algorithm for finding a minimum feedback set. A feedback set is a set of edges that contains at least one edge of each directed circuit of the graph. A lower bound on the cardinality of a feedback set of a directed graph G is given by the cardinality of a maximum disjoint collection of directed circuits of G. The lower bound is not reached for all graphs, but experiment suggested that it is attained for all planar graphs. The attainment of this lower bound is equivalent, for planar graphs, to the attainment in the dual graph of the analogous lower bound for the cardinality of a transversal of directed cuts. This equivalence for planar graphs does not hold for all graphs. Indeed, the conjectured minimax equality, in its directed cut formulation, was extended to include all finite directed graphs. This is the Theorem which this paper proves; the following Dual Theorem is a corollary.
229 citations
TL;DR: An algorithm is presented that finds K, the set of all keys for agiven set A of attribute names and a given set D [0] of functional dependencies, in time polynomial in A, D, and |K|.
167 citations
TL;DR: In this article, the structure of the monomethyl ether of isolariciresinol has been established based on the 13 C NMR spectra of these compounds, their methyl and acetyl derivatives, and the corresponding one of matairesinols.
126 citations
TL;DR: Evidence is presented that at least one group of insect herbivores corresponds in many details to predictions derivable from competition and foraging theory and some of the more important details and extensions of these predictions are discussed.
Abstract: The use of phytophagous insect communities as model systems to elucidate ecoevolutionary processes, although encountering considerable success in some areas (Southwood, 1960, 1961; Opler, 1974; Strong, 1974a,b), has not been actively extended to include competitive phenomena. The partitioning of food resources has been well documented in many animal groups, especially vertebrate predators (Schoener, 1974); however, the few studies made to date have not presented convincing evidence that such patterns are typical for any group of invertebrate herbivores. Several possible cases of competition related resource partitioning between pairs of lepidopteran species have been reported by Gilbert and Singer (1976) from an extensive examination of the lepidopteran literature, and Shapiro and Carde (1970) suggested that host plant and habitat separation among three species of satyrine butterflies may be explicable in terms of competition induced ecological shifts. On a larger scale Owen (1972) noted that the patterns of host plant use in West African acraeine butterflies are consistent with resource partitioning. On the other hand, very few studies have specifically examined the dynamics of resource use as related to competition. Colwell (1973) has presented a convincing picture of the ecological dynamics accounting for host plant separation of two potentially competing nectivorous mites. However, the only study to date specifically designed to identify partitioning within an insect herbivore guild failed to reveal clearcut patterns among temperate stem-borers (Rathcke, 1976). Moreover, theoretical arguments have been put forward to suggest that unambiguous patterns of resource partitioning are not generally to be expected in invertebrate herbivores, and May (1973:166) goes even farther in stating that ". many insect communities, and many plant communities, have complex multidimensional niche structure involving, inter alia, a variety of chemical dimensions. In addition predation and other interactions beyond simple competition are pervasive in these invertebrate and plant communities. Such situations are best avoided for the time being." I present here evidence that at least one group of insect herbivores corresponds in many details to predictions derivable from competition and foraging theory and discuss some of the more important details and extensions of these predictions.
110 citations
01 Jan 1978
TL;DR: In this article, the theory of transformation relations between states of Born Oppenheimer and weak coupling approximations is developed for polyatomic molecules, which are a generalization of frame transformation relations used by Chang and Fano for symmetric-top molecules, and they lead to a more convenient symmetry labeling system than was previously available.
Abstract: The theory of transformation relations between states of Born Oppenheimer and weak coupling approximations is developed for polyatomic molecules. The relations are a generalization of frame transformation relations used by Chang and Fano for symmetric-top molecules, and they lead to a more convenient symmetry labeling system than was previously available. A key internal symmetry label (named ''soul'') is defined so that it remains a constant label for frame transformation relations, and is conserved during vibronic transitions, ionization, and even dissociation provided the nuclear spin--rotation interaction is relatively small. Various nomograms, graphs, and tableaus associated with the soul label make it easy to predict and visualize the form of many types of complex high-resolution spectra. Simplified procedures are given for obtaining selection rules, statistical weights, and matrix elements of multipole operators for common molecules having various point symmetries. Simplifications of computational theory using the new level cluster bases for high J are discussed.
91 citations
TL;DR: Elemicin, galbacin, veraguensin and two new neolignans, surinamens in and virolin, were isolated and characterized from the leaves of VirolaSurinamensis.
90 citations
TL;DR: In this paper, the two-phonon mode of the disorder-induced line was found at 1370 cm-1 for single crystal and polycrystalline graphites having disorder.
86 citations
67 citations
01 Dec 1978-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a new mathematical model for unidirectional solidification via heat extraction through massive uncooled molds of effectively semi-infinite thickness was proposed and compared with predictions for the case of lead and the effect of mold thickness in the effectively finite regime.
Abstract: In this paper, a new mathematical model recently outlined by the present authors 1 is applied to the case of unidirectional solidification via heat extraction through massive uncooled molds of effectively semi-infinite thickness. The model permits measurement of the Newtonian heat transfer coefficient at the metal/mold interface and a complete description of the kinetics and thermal characteristics of solidification is subsequently possible. Experimental results are compared with predictions for the case of lead and the effect of mold thickness in the effectively finite regime is also investigated.
65 citations
TL;DR: In this article, a 17-point hedonic scale and discrimination taste thresholds were determined in a coffee beverage containing 0, 2.5, 5, 5.0, 7.5 and 10.
Abstract: Degree of liking, using a 17-point hedonic scale, and discrimination taste thresholds, using a paired-comparison technique, were determined in a coffee beverage containing 0, 2.5, 5.0, 7.5, and 10. ...
53 citations
TL;DR: The menstrual patterns of women using subdermal implants of levonorgestrel and norgestrienone included in a double-blind clinical trial was evaluated by the method developed by the International Committee on Contraception Research.
TL;DR: The authors concluded that the ideal clinical consistency is obtained when the mixture can be picked up and held with the spatulas upside down without dropping off for 10 seconds, or when its fluidity permits adherence between the spatula and the glass slab up to a height of 2 cm.
TL;DR: In this article, the 13C NMR spectra of some isoquinoline and tetrahydroisoquinoline alkaloids and their corresponding N-methosalts were recorded and the signals assigned.
TL;DR: In this article, the authors showed that 3-methyl-3,4-dihydroisocoumarins can be distinguished from 3-mellein by MS.
TL;DR: Germination ofCucumis anguria was inhibited by white, blue, and far-red (FR) irradiation and promoted by darkness and red (R) irradiated and the effect of white light was greater when supplied after rather than before the dark period.
Abstract: Germination ofCucumis anguria was inhibited by white, blue (B), and far-red (FR) irradiation and promoted by darkness and red (R) irradiation. The effect of white light was greater when supplied after rather than before the dark period. Darkness was more effective in reversing the effect of FR than FR in reversing the effect of darkness. FR was also more effective than B. When darkness followed B pretreatments, final germination percentage was higher than with FR pretreatment. R fully reversed the inhibitory effect of FR.
TL;DR: In this paper, an alternative proof via matrix equations was given for the stability criterion of Lienard and Chipart, which is simple and elementary and can be used for any stability criterion.
TL;DR: In this paper, the theoretical interpretation of the spectroscopy data is outlined on the basis of the coupling of the usual scattering theory with Zubarev's non-equilibrium statistical operator method.
TL;DR: In this article, four basic types of natural convection solar air heaters, in many geometries, were tested in a wide range of input solar energy values and measured values of air flow rate, temperature increase and efficiency were reported.
TL;DR: In this article, a strong change in reflectivity with temperature was reported, and transmission measurements in the nonsaturated or Urbach's region were done from room temperature up to 853 K.
Abstract: Transmission measurements in the nonsaturated or Urbach’s region were done from room temperature up to 853 K. A strong change in reflectivity with temperature is reported.
TL;DR: Os rapidos ganhos geneticos obtidos confirmam ser a suscetibilidade de moluscos a infeccao esquistossomotica, uma caracteristica de alta herdabilidade, sendo aparentemente condicionada por um pequeno numero de genes.
Abstract: Utilizando um esquema de selecao individual em progenies autofecundadas, foram obtidas, apos quatro geracoes, populacoes de Biomphalaria tenagophila e de Biomphalaria glabrata, altamente suscetiveis as linhagens do Schistosoma mansoni do Vale do Rio Paraiba do Sul, SP e de Belo Horizonte, MG (Brasil), respectivamente Os rapidos ganhos geneticos obtidos confirmam ser a suscetibilidade de moluscos a infeccao esquistossomotica, uma caracteristica de alta herdabilidade, sendo aparentemente condicionada por um pequeno numero de genes
TL;DR: Using a combination of gas chromatography and spectrometry, 20 major components from an extract of distillate from jack fruit were identified as mentioned in this paper, including esters and four aliphatic alcohols.
Abstract: Using a combination of gas chromatography and spectrometry, 20 major components from an extract of distillate from jack fruit were identified. Of these, 16 were esters and four aliphatic alcohols. The total absence of terpenoids in jack fruit is unique in the plant kingdom.
TL;DR: “In vitro” translation of RNA extracted from the different segments of the salivary gland of R.W. americana indicates that the 21,000 M.W.'s peptides produced by the gland, and which were previously assigned to the B-2 and C-3 “DNA puffs”, are coded by [poly(A) + ]RNA.
TL;DR: In this article, it was shown that the three modes observed in the A1(TO) phonon spectrum of tetragonal BaTiO3 are first order, and these results were interpreted as supporting the order-disorder model of the ferroelectric phase transition.
Abstract: Evidence is presented, based on Raman scattering measurements, that the three modes observed in the A1(TO) phonon spectrum of tetragonal BaTiO3 are first order. These results are interpreted as supporting the order-disorder model of the ferroelectric phase transition.
TL;DR: In this article, the first-order many-body theory (fombt) has been applied to the calculation of orientation and alignment parameters (λ and χ) in the case of electron impact excitation of the 31P state of He at 50 and 80 eV impact energies.
Abstract: The first-order many-body theory (fombt) has been applied to the calculation of orientation and alignment parameters (λ and χ) in the case of electron impact excitation of the 31P state of He at 50 and 80 eV impact energies. The results obtained are compared with experimental results and with those of other theoretical models.
TL;DR: Aniba rosaeodora wood was shown to contain rubranine by pyrolysis and synthesis, involving previously reported pyridine-catalysed condensation of pinocembrin and citral, whereby novel intermediates were prepared as discussed by the authors.
TL;DR: In this article, spline-based filters were proposed to obtain the same accuracy as in the classical ten-sor product approach considering a reduced set of points, and the feasibility of the non-linear filter is shown by some simulation examples for systems of first and second order.
TL;DR: The structure of chromatin during spermiogenesis of a lizard was examined and it was found that the fibrillar nature of Chromatin is maintained during all time even in the mature sperm, but the fibers pass through a process of thickening and reorganization.
Abstract: The structure of chromatin during spermiogenesis of a lizard was examined. The fibrillar nature of chromatin is maintained during all time even in the mature sperm, but the fibers pass through a process of thickening and reorganization which begins with a homogeneous and diffuse aspect, going through an organization of chromatin fibers parallel to the long axis of the nucleus, disposed concentrically but not evenly displaced. In a final stage the fibers are thicker and closely packed showing almost no nucleoplasm among them.