Showing papers by "State University of Campinas published in 1985"

Genetics and the Evolution of Muellerian Mimicry in Heliconius Butterflies

Abstract: A protected and warningly coloured butterfly can become a muellerian mimic of another species in two steps: (i) a major mutation converts the pattern of the less protected species to an approximate resemblance of the better protected (one-way convergence); (ii) after the spread of this mutant, the species, which now resemble each other sufficiently to be mistaken one for the other by predators, undergo mutual convergence, using whatever major or minor genetic variation is available to them. Although sometimes one or other step might occur alone, in general early theorists were mistaken in attributing muellerian mimicry to only one of these processes. By hybridizing races of Heliconius melpomene and races of H. erato (a pair of parallel mimetic species from the neotropics, held in mutual muellerian mimicry across wide inter-racial variations in colour pattern) we have shown that, as expected from the two-step theory, the races differ at a number (two to nine) of genetic loci, usually unlinked or loosely linked, including at least one mutant of major effect in each case. We describe the genetic constitution of eight races of H. melpomene (for 11 loci affecting colour pattern) and of eight races of H. erato (for up to 15 loci), and have started to identify the linkage groups. Map distances for those loci that are linked range from around 0.3 to zero in males, with no recombination in females. Muellerian mimicry is expected to produce total uniformity of pattern: universal exceptions to this are the existence of distinct mimicry rings flying within the same habitat, geographical variation within nearly all the more widespread species (divergence in the face of normalizing selection), and, in a few species, polymorphism or sexual dimorphism. Sympatric mimicry rings will, according to the two-step model of evolution, persist indefinitely if their patterns are so distinct that under no circumstances do predators mistake one for the other. Gradual mutual convergence is then impossible, although members of a weakly protected mimicry ring that can produce a mutation giving sufficient initial resemblance to a better protected ring can still be captured by it. Batesian mimics promote this by lowering the protection of the ring that they belong to, but their models can escape only in this way as normalizing selection prevents their gradual evolution away from the batesian mimic. If the rings are too distinct in pattern even this capture of species becomes impossible as no single mutant is able to bridge the gap between the two patterns, and the necessary two mutations will be extremely unlikely to occur together. The five principal sympatric mimicry rings of the mature neotropical rain forests are very distinct in their appearance. The capture of a species by another ring can produce geographical variation both in the species captured and in the capturing ring, whose pattern is somewhat altered by mutual convergence with the captured species in the second step of the evolution of the muellerian resemblance. We suggest that the striking differences between the races within H. melpomene, H. erato and other Heliconius species resulted from these effects of inter-ring capture. Distributional evidence suggests that this chiefly occurred in refuges formed by the contraction of the neotropical rain forests during the cool dry periods in the Quaternary; these, by differential extinction of elements of the flora and fauna of different refuges, could have produced long-term changes in the relative abundances of the mimicry rings, and hence (as the protection given to a ring is proportional to its abundance) somewhat different capture events in each refuge. Several existing species confirm that this mode of evolution occurs, by retaining a distinctive pattern in the absence of any other remotely similar species, but becoming mimetic in areas where they encounter a pattern somewhat like their own. The isolated populations of Heliconius hermathena show this particularly clearly; the effect can be discerned also in H. melpomene and H. erato. Although polymorphism in muellerian mimics is largely unexplained, in two species of Heliconius it may result from the existence of two or more similar but slightly differing 9sub-rings9 among their comimics in the family Ithomiidae, which show both spatial and temporal heterogeneity in their local distribution, which apparently is able to maintain a polymorphic equilibrium in the more uniformly distributed Heliconius. We have tentatively reconstructed the ancestral patterns of H. melpomene and erato by two independent methods: first, as dominant genes are much more likely to be incorporated than recessive ones during changes of pattern, the phenotype produced by the recessive alleles at all the known loci will be close to the ancestral pattern; secondly, species that are becoming mimics evolve more than those that are not, so that non-mimetic relatives of melpomene and erato will have a pattern close to ancestral. Both methods suggest, for both species, that the ancestor was a black butterfly with yellow (or possibly white) bars, and it may be that melpomene and erato have been comimics for a very long time. Previous climatic cycles in the Quaternary have apparently caused full speciation within two mutually mimetic evolving lineages, producing pairs of parallel mimetic species within the genus, of which melpomene and erato constitute one pair.

A Hybrid State Estimator: Solving Normal Equations By Orthogonal Transformations

Abstract: The standard approach to the solution of the weighted least square (WLS) state estimation in power system is the iterative normal equations method. Occasional ill-conditioning has been experienced with this method. Recently alternative solution approaches based on orthogonal transformations have been proposed. Sparsity generally suffers in these methods. In this paper, the network condition which causes ill- conditioning is studied. A hybrid approach which enjoys the same numerical robustness of the orthogonal methods with sparsity close to the standard WLS method is presented. The modification needed to implement the hybrid method on an existing standard WLS state estimation program is quite small.

Effect of metergoline on human anxiety

Abstract: In order to assess the role played by serotonin (5-HT) in subjective anxiety, three groups of 12 healthy volunteers were given 12 mg metergoline (MET), 10 mg diazepam (DZ) or placebo (PB), under double-blind conditions, and submitted to a simulated public speaking (SPS) test. MET increased state-anxiety scores, measured by Spielberg's State-Trait Anxiety Inventory. The effect of MET was significantly different from both the PB and DZ groups immediately before the SPS test (prestress) as well as 24 h after medication, and from the DZ group only, 2.5 h after the test (poststress). In contrast, DZ did not significantly affect subjective anxiety. The SPS test significantly increased anxiety in DZ- or PB-treated subjects as compared to prestress scores, whereas the increases in the MET group were not significant, probably because pretest levels were already high. No drug effect on heart rate, skin electrical conductance and quality of sleep during the night following medication was found. In addition, the drugs did not cause bodily symptoms that could secondarily affect mood. Since MET is a 5-HT receptor antagonist, active on the central nervous system, an inhibitory role of 5-HT on subjective anxiety might be suggested.

The completeness and compactness of a three-valued first-order logic

Abstract: The strong completeness and the compactness of a three-valued first order predicate calculus with two distinguished truth-values are obtained. The system was introduced in Sur un prcb leme de Jaskowski, I .M.L. D.'Ottaviano and N.C. A. da Costa, C.R. Acad.Sc. Paris 270A (1970) , pp.1349-1353, and has several applications, especially in paraconsistent logics.

Use of water hyacinths as shelter, foraging place, and transport by young piranhas, Serrasalmus spilopleura

Abstract: The water hyacinth, Eichhornia crassipes, plays an important role in the early life of the piranha, Serrasalmus spilopleura in southeastern Brazil. Larvae and early juveniles are found by both day and night among the roots of this free floating waterweed, thus gaining shelter, a rich foraging place, and potential rafting dispersal. Piranha larvae up to 19 mm SL feed mainly on small aquatic arthropods, slowly searched for inside the root tangle; larger juveniles tend to leave the plants and patrol more open areas. At 24 mm SL young piranhas begin to clip out pieces from fins of other fishes and seek shelter in water hyacinths only at night. About 30% of the rafting clumps of water hyacinths may harbour one to three piranha larvae, providing dispersal during floods.

Compact Conformally Flat Hypersurfaces

Abstract: Roughly speaking, a conformal space is a differentiable manifold \(M^n\)in which the notion of angle of tangent vectors at a point \(p \in M^n\)makes sense and varies differentiably with p; two such spaces are (locally) equivalent if they are rela ted by an angle-preserving (local) diffeomorphism. A conformally flat space is a conformal space locally equivalent to the euclidean space R n. A submanifold of a conformally flat space is said to be conformally flat if so its induced conformal structure: in particular, if the codimension is one, it is called a conformally flat hypersurface. The aim of this paper is to give a description of compact conformally flat hypersurfaces of a conformally flat space. For simplicity, as~ume the ambient space to be R n+1. Then, if \(n \geqslant 4\), a conformally flat hypersurface \({M}^{n} \subset {R}^{n+1}\) 1 can be described as follows. Diffeomorphically, M n is a sphere S n with h1( M) handles attached, where h1 ( M) is the first Betti number of M. Geometrically, it is made up by (perhaps infinitely many) nonumbilic submanifolds of R n+1 that are foliated by complete round (n – 1 )-spheres and are joined through their boundaries to the following three types of umbilic submanifolds of R n+1: (a) an open piece of an n-sphere or an n-plane bounded by round ( n – 1 )-sphere, (b) a round ( n – 1 )-sphere, (c) a point.

Decentralised load-frequency control

Abstract: In the paper we propose a numerical procedure to determine the load-frequency control of a power system composed of several interconnected areas. In order to decrease the associated implementation cost, the control law is constrained to have two different special structures: decentralised feedback and/or output feedback control. The procedure is based on a new property of the classical Riccati equation which is analysed in two different aspects: closed-loop asymptotic stability and suboptimality degree. An example of two interconnected areas is solved and comparisons are made in order to evaluate the performance of the closed-loop system.

Effect of Storage Conditions of Dry Bean Seeds (Phaseolus vulgaris L.) on Texture Profile Parameters After Cooking

Abstract: Red kidney beans were stored at constant moisture and high and low temperature for 6 months Instrumentally measured parameters of hardness, fracturabihty, gumminess, chewiness, springiness and cohesiveness were higher in samples stored at elevated temperatures than the control (2°C) The sensory panel found the stored beans had higher hardness, fracturability, lumpiness, chewiness, and skin toughness and less starchiness, gumminess, pastiness and moisture absorption than the control Puncture forces followed approximately a normal distribution curve, and there was always some overlap between stored and control beans even when the stored beans had a much higher mean puncture force than the control All textural parameters of cooked bean cotyledons changed substantially during storage of the seeds at elevated temperatures and high relative humidity

On the determination of a diagonal solution of the Lyapunov equation

Abstract: In this note, for a given matrix A , the solution of the Lyapanov equation A'P+ PA + Q = 0 , considering P diagonal or both P and Q diagonal matrices, is investigated. For this purpose a simple algorithm based on nonlinear programming is presented.

Laser surgery in enclosed spaces: a review

Abstract: We describe the results of experiments carried out in the arteries of dogs, rabbits, guinea pigs, and humans, normal or atheromatous, calcified, or not, with the application of the argon and CO2 laser, in vitro or in vivo, directly or indirectly. Similarly, we present the results of laser effects when radiation is delivered through a special catheter with the purpose of producing aortic insufficiency, opening pulmonary valvular stenosis, desobstructing carotid and coronary obstruction induced in dogs as well as atheromatous obstructions in human amputated legs. Arterial wall perforation was present in 50% of all cases. We suggest four options in order to diminish this adverse result: (1) the use of coherent optical bundles which will allow the proper guiding of the laser beam, (2) the construction of a special catheter for proper handling of the laser-carrying fiber, (3) a combination of optical and computer programs which will aid to identify calcified regions, and (4) the use of dyes which will be strongly and selectively absorbed by the atheromas and which will thus allow their destruction at low laser powers.

Uma nova espécie de Crossodactylus da Serra do Cipó, Minas Gerais, Brasil (Amphibia, Leptodactylidae)

Abstract: Crossodactylus bokermanni, sp. n., is described from Serra do Cipo, Minas Gerais, Southeastern Brasil. The new species is characterized by the small size (20-27 mm), slender build, long legs, narrow head, long and acuminate snout, rounded but fairly defined canthus rostralis, and small tympanum. Also, notes on its habits are made and its tadpole is described.

The Tolman-Regge Antitelephone paradox: its solution by tachyon mechanics

Abstract: The possibility of solving (at least « in micropliysics ») all the ordinary causal paradoxes devised for tachyons is not yet widely recognized; on the contrary, the effectiveness of the Stuckelberg-Feynman « switching principle » is often misunderstood. We want, therefore, to show in detail and rigorously how to solve the oldest causal paradox, originally proposed by Tolman, which is the kernel of so many further tachyon paradoxes. The key to the solution is a careful application oftachyon kinematics, which can be unambiguously derived from special relativity. A systematic, thorough analysis of all tachyon paradoxes is going to appear elsewhere.

Crescimento urbano e doença: a esquistossomose no município de São Paulo (Brasil)

Abstract: The role of the urban development of the city of S. Paulo (Brazil) is presented, in this study, in the light of the appearance of condition favorable to the establishment of the transmission of schistosomiasis in southeastern Brazil which is usually seen as a consequence of migration from the Northeast where the disease in endemic. Studies of the distribution of schistosomiasis in S. Paulo have given an exaggerated importance to migration. The spread of the disease in the municipality of S. Paulo (Brazil) is an example of a situation where the pattern of urban growth has been more relevant than migration. The occupation of the lowlands from the late 1950's onwards brought about the conditions for the establishment of disease foci. Up to then this was not possible for urbanization occurred exclusively in more elevated areas. Without a shift in the pattern of urbanization schistosomiasis wouldn't have occurred in the city of S. Paulo, despite intense migration.

Screening and quantitation of ochratoxin A in corn, peanuts, beans, rice, and cassava.

Abstract: To answer the need for simple, economical, rapid methods for mycotoxins, a procedure for screening and quantitation of ochratoxin A was developed. A methanol-aqueous KCl extraction is used, followed by cleanup with clarifying agents and partition into chloroform. Part of the chloroform extract is used for screening and the other part for quantitation by thin layer chromatography (TLC). The screening procedure takes 40 min, using a silica gel/aluminum oxide minicolumn developed for this purpose. The limits of detection are 80 and 10 micrograms/kg, respectively, for minicolumn screening and TLC quantitation. Ammonium sulfate is efficient in cleaning samples of corn and cassava; cupric sulfate is better with peanuts, beans, and rice. Tests were conducted on triplicate spiked samples of yellow corn meal, raw peanuts, dried black beans, polished rice, and cassava flour at different levels (400, 200, 80, 40, and 10 micrograms/kg). Recoveries ranged from 86 to 160% and the coefficients of variation ranged from 0 to 26%.

Optical properties of non-stoichiometric germanium nitride compounds (a-GeNx)

Abstract: In this paper some optical properties of non-stoichiometric germanium-nitrogen compounds (a-GeN x ) are presented. It is shown that the inclusion of nitrogen atoms into the Ge network produces a band gap widening. The use of hydrogen to passivate the gap states of the material is also discussed.