89 resultados para Platinum group elements


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Acanthagrion cuyabae Calvert, 1909 was described based on a male from State of Mato Grosso, Brazil. The female of this species was described based on morphological characters of four individuals collected in copula from State of Mato Grosso do Sul, and three other specimens of same locality. Acanthagrion cuyabae is here revalidated based on morphological characters of the female. Illustrated keys to the groups of Acanthagrion Selys, 1876 and species of the viridescens group occurring in Brazil are provided.

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The genus Sporophila (Cabanis, 1844) unites about 30 species of small seedeaters that predominantly inhabit open or semi-open areas in the Neotropical region. The taxonomy of this group is based on morphological studies from collected male specimens. The dynamic spatial and temporal variation in the male plumage and lack of knowledge of their vocalizations make it difficult to properly diagnose some species even today, so these two aspects account for the existing taxonomic dilemmas involving Sporophila. During a four-year field study, we investigated the natural history of a breeding population of Sporophila melanogaster (Pelzeln, 1870). This is an endemic species in Brazil, which reproduces in the high-altitude grasslands of the Atlantic Forest biome. We found four male specimens with clearly diagnosable plumage, distinct from the typical form of the species. Here we describe this previously unreported plumage form. Based on the evaluation of habitat use, vocalization, and reproductive behavior, we tested two hypotheses regarding its taxonomic status. We concluded that this is another case of an intra-specific color morph within the seedeaters of the "capuchinos" group.

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The Drosophila peruensis species group was recently proposed and includes four taxa: D. atalaia Vilela & Sene, 1982, D. boraceia Vilela & Val, 2004, D. pauliceia Ratcov & Vilela, 2007, and D. peruensis Wheeler, 1959. All these species have most of setae or setulae of mesonotum arinsing from dark spots, wings with crossveins darker (except in D. atalaia) and hypandrium squared-shaped mostly fused to gonopods. Here, we describe two new species, Drosophila itacorubi sp. nov. and Drosophila paraitacorubi sp. nov., belonging to this species group. The male genitalia of these species are figured. An identification key to the D. peruensis species group is provided.

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The new genus Neodrassex is proposed to include two new species of Gnaphosidae from Brazil. Neodrassex aureus sp. nov. is described from Amazonas, Paraná and Rio Grande do Sul states, and N. iguatemi sp. nov. is described from Paraná state. Neodrassex gen. nov. is characterized by small size, pale coloration, large anterior median eyes surrounded by black pigmentation, absence of a dorsal abdominal scutum in males and by the cheliceral dentition with 2-3 teeth on the promargin and 2-4 on the retromargin. The new genus is tentatively placed at the Leptodrassex group.

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After going through the more important theories on cellular permeability, researches were undertaken with the purpose of proving the actual influence of the various degrees of cellular permeability on the phenomena of organic resistance against infections, and on the production of antibodies. Three groups of substances known to have action on cellular permeability were used; the first consisting of the following permeable substances: testos-terona, acetylcholine, and the spreading-factor of the staphyloccocus. The second group included substances which help in developing low cellular permeability: atropin, adrenalin and calcium. Finally, the third group consisted of a substance which helps to maintain normal permeability: cortin (an extract of the suprarenal cortex). In order to study the process developed by these elements with regard to organic resistance against infections, adult mice were inoculated with the following germs: K. pneumoniae, P. aeruginosa, S. enteriditis and D. pneumoniae, in the smallest possible amount capable of starting a mortal sep infection in approximately 24 hours, exception made of D. pneumonias which causes death in 48 hours. The animals were divided into groups of 10, a before taking the injections containing the germs, they were given the sub lances under observation, through their peritoneum of intramuscularly. T. animals that died were autopsied and blood was taken from their hearts an aseptic process so as not to introduce extraneous organisms. For the purpose of determining the development of antibodies (hem lysins, precipitins and aglutinins), rabbits were used, which had been prep ously immunized by a treatment consisting of 6 intravenous injections of polyvolent antigen made of sheep blood cells, fresh human serum, and of suspension of S. enteriditis. It was concluded that: Cellular permeability plays a very important part in the development infections. Permeable substances help the development of germ infections. Substances helping to develop low permeability proved not to have any influence worth mentioning. Substances helping to maintain normal permeability, such as coffin, it crease resistance against infections. The different substances used which have action on cellular permeability had no influence worth mentioning on the development of certain ant bodies (hemolysins, precipitins and aglutinins). It was admitted that the phenomena under study relative to resistance against infections are closely connected to the dynamics of the cellular elements, which circumstance is basically dependent on the permeability of Citations of cells.

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It is well-known that diverse groups of vegetation with an analogous but not identical floristic composition show an ecological similarity which leads to a determined type of vegetation. Starting from this fact it becomes evident that the scope of phytosociological work is the establishing of the significance of the species within the association and the discovery of the rules which govern associations. The floristic surveys made in the field have to be analysed statistically so as to obtain satisfactory results. The usefulness of this method depends largely on the possibilities of comparing the results with previous studies of the same kind, in the same country, or elsewhere. The method used in this paper is that of measuring circumferences and counting individuals in the different associations studied because it permits the presentation of the results in tables which show the phytosociological complexity of the Brazilian rain-forests. The classical method of characteristics is valuable because the more evolved an association is the less sociable are the species it contains, so that such groups do not show clear differences between species but rather between sinusia or strata of individuals. Five tables are presented in which several of the qualitative and quantitative characteristics are studied with a view to discussing their value in relation to groups and species. They are: I - Abundance (number of individuals). II - Density (distance in meters between the individuals belonging to each stratum). III - Basal coverture (circles measured in square meters of the mean projection of the individuals on the surface). IV - Basal area (mean circle in square meters occupied by individuals on the surface). V - Frequency, abundance and sociability in relation to occurrence. TABLE I. This table indicates first the number of individuals in relation to the sinusia studied: next, the sum total of the individuals belanging to the strata are given for each association, thus providing the numeric value of the sinusia: finally, the relation between the total number of individuals in the association and the total for the sinusium thus fursnishing the abundance per sinusium, in the classic sence, that is the percentage, or rather the relative number, of the elements which compose the group. CONCLUSIONS. The general character of abundance of the regional vegetation of Ilheos may be summed up in the following way: as an association evolves towards permanent equilibirum the number of individuals the inferior strata diminishes in relation to those of the superior strata which increase. For the shrub sinusium, two important facts were observed: a) in a given association the number of elements of the inferior strata diminishes as the diameter of the individuals increases; b) the percentage of individuals belonging to the shrub sinusium in the sere diminishes as the association evolve. In the subarboreal sinusium it is seen that: in the sere the number of subarboreal individuals does not vary much; whereas in the climax or the prisere there is a fall owing to the equilibrum of the biologic forms. In the arboreal sinusium the following conclusion can be deduced from analogous facts: the number of individuals of the lower strata diminishes as circumference increases. Also, in the sere there is a progressive sequence for the individuals belonging to the superior strata. TABLE II. The relation between the mean distances of individuals belonging to the same stratum and the area of an association is equal to the density. The table shows that the mean density of the association and the distance between the individuals belonging to the strata of the same sinusium in relation to the total number of individuals belonging to the association. CONCLUSIONS. As rule, the density of individuals in the associations studied follows a very general character or at least a regional one: the distance between the individuals in the diverse strata varies according to their abundance and sociability. Two other facts of some sociological importance are: a) in identical strata of the same sere the density of individuals oscillates in an analogous manner in teh subclimaces and varies in the stages which have reached equilibrium. b) the density of individuals varias in accordance with the sinusium and the distances between individuals of the same sinusium varg in accordance with the strata. TABLE III. This table presents the mean basal individual coverture, that is the mean projection of the frond of the various individuals belonging to the same stratum. The means were obtained by measurement in the field, of 100 individuals belonging to each stratum and their projection on the surface. In the latoratory these measurements were converted into mean circles (in square meters) and the result was multiplied by the individuals belonging to the strata corresponding to the sinusium of each association. The result obtained is named basal coverture. CONCLUSIONS. As a rule, the basal coverture of the vegetation of the county of Ilhéus indicates that: in the evolution of the vegetation the basal coverture of the arbustive sinusium diminishes progressively whereas that of the arboreal one increases. The special norms obtained are: 1) in the shrub sinusium the basal coverture seems to follow a uniform norm, that is, in stages of evolution of the subclimax the basal coverture oscillates with a certain uniformity. 2) in the subarboreal sinusium this fact is related to the vitality and age of the species, as in the subclimax the number of young trees is large and the vitality of the species very variable. This permits the conclusion that: in the sere the basal coverture increases with the evolution of the vegetation and diminishes when an equilibrium is reached. 3) in the tree sinusium the climax association of the prisere and subsere seem to obey a binomial rule, as the coverture (density-abundance) increases until a determined stratum is reached and...

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The adult, pupal and larval morphology of S. argentiscutum sp. nov., a member of the S. amazonicum-group, is compared with S. amazonicum Goeldi and its distribution, biology and medical importance are discussed. S. argentiscutum is one the most important anthropophilic species in the S. amazonicum-group as it is responsible, together with S. amazonicum, for the transmission of Mansonella ozzardi in Brazil.

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Six species of phlebotomine sand flies in the genus Lutzomyia França from South America are included in the newly-created species group microps. References and illustrations of the species are given, including descriptions of two new forms - L. nematoducta n.sp., male and female from northern Brazil, and l. preclara n.sp. male from Colombia and Peru. The males in the species group microps are keyed.

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The male and female of Lutzomyia carmelinoi n.sp., and the female only of L. baculus and L. williamsi, (Diptera:Psychodidae) are described and illustrated from specimens collected in Pará state, Brazil. A pictorial key is presented to these and the other members of the walkeri group.

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Notes are presented on the three known Neotropical species of the Culicoides stigmalis group of boodsucking midges: alvarezi Ortiz, fluviatilis (Lutz), stigmalis Wirth, and on deanei n.sp., which is described from the state of Rio de Janeiro, Brazil. A diagnosis is given for the group, as well as a key for identification and comparative phtographs of the female wings.

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Species of sandflies in the oswaldoi-group of the genus Lutzomyia occuring in Venezuela are reviewed. A new species, Lutzomyia saccai n. sp. is described. A distribution map and pictorial keys for males and females are provided with notes on biological and ecological data collected in Venezuela.

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Throphozoites of Giardia duodenalis group obtained from fragments or scratched of hamster's mucosa were examined by transission electron microscopy. The fine structure of the trophozoites are presented and comapred with those described for other animals. Some of the trophozoites present the cytoplasm full of glycogen, rough endoplasmic reticulum-like structures and homogeneous inclusions not enclosed by membranes, recognized as lipid drops, which had not been observed in Giardia from other animals. The adhesive disk is composed of a layer of microtubules, from which fibrous ribbons extend into the cytoplasm; these ribbons are linked by layer of crossbridge filaments that shows an intermediary dense band, described for the first time in this paper. The authors regard this band as the result of the cross-bridge filaments slinding in the medium region between adjacent fibrous ribbons, and suggest a contractile activity for them. The role of the adhesive disk on the trophozoite mechanism of attachment to host mucosa is also discussed.

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The influence of the subminimal inhibitory concentrations (1/3 and 1/4 of the MIC) of penicillin on growth rate and on haemolysin production of a strain of group G Streptococcus was studied. It was shown that 1/3 of the MIC almost completely inhibited the bacterial growth, but it was not able to inhibit haemolysin activity in the culture supernate. The generation time of bacteria grown in 1/4 of the MIC was approximately twice longer than that of the control culture. In all cultures, the haemolysin, after being produced (or liberated), reached a peak and decreased to low levels, which could suggest that group G Streptococcus produces some end products of metabolism that are able to inhibit haemolysin activity.

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A new Brazilian species of the Culicoides limai group. C. lobatoi from Nova Friburgo, State of Rio de Janeiro, is described and illustrated from female specimens.