Repositório RCAAP

We show that the Hopf differentials of a pair of isometric cousin surfaces, a minimal surface in euclidean 3-space and a constant mean curvature (CMC) one surface in the 3-dimensional hyperbolic space, with properly embedded annular ends, extend holomorphically to each end. Using this result, we derive conditions for when the pair must be a plane and a horosphere.

We show that immersed minimal surfaces in the euclidean 3-space with bounded curvature and proper self intersections are proper. We also showthat restricted to wide components the immersing map is always proper, regardless the map being proper or not. Prior to these results it was only known that injectively immersed minimal surfaces with bounded curvature were proper.

The positioning of macrochromosomes of Bothrops jararaca and Bothrops insularis (Viperidae) was studied in undistorted radial metaphases of uncultured cells (spermatogonia and oogonia) not subjected to spindle inhibitors. Colchicinized metaphases from uncultured (spleen and intestine) and cultured tissues (blood) were also analyzed. We report two antagonic non-random chromosome arrangements in untreated premeiotic cells: the parallel configuration with homologue chromosomes associated side by side in the metaphase plate and the antiparallel configuration having homologue chromosomes with antipolar distribution in the metaphase ring. The antiparallel aspect also appeared in colchicinized cells. The spatial chromosome arrangement in both configurations is groupal size-dependent and maintained through meiosis. We also describe, in untreated gonia cells, endomitosis followed by reductional mitosis which restores the diploid number. In B. jararaca males we observed that some gonad regions present changes in the meiotic mechanism. In this case, endoreduplicated cells segregate the diplochromosomes to opposite poles forming directly endoreduplicated second metaphases of meiosis with the suppression of first meiosis. By a successive division, these cells form nuclei with one set of chromosomes. Chromosome doubling in oogonia is known in hybrid species and in parthenogenetic salamanders and lizards. This species also presented chromosome rearrangements leading to aneuploidies in mitosis and meiosis. It is suggested that somatic pairing, endomitosis, meiotic alterations, and chromosomal aberrations can be correlated processes. Similar aspects of nuclei configurations, endomitosis and reductional mitosis were found in other Viperidae and Colubridae species.

Lutzomyia longipalpis is the most important vector of AmericanVisceral Leishmaniasis (AVL) due to Leishmania chagasi in the New World. Despite its importance, AVL, a disease primarily of rural areas, has increased its prevalence and became urbanized in some large cities in Brazil and other countries in Latin America. Although the disease is treatable, other control measures include elimination of infected dogs and the use of insecticides to kill the sand flies. A better understanding of vector biology could also account as one more tool for AVL control. A wide variety of papers about L. longipalpis have been published in the recent past years. This review summarizes our current information of this particular sand fly regarding its importance, biology, morphology, pheromones genetics, saliva, gut physiology and parasite interactions.

The Arenópolis volcano-sedimentary sequence is located in the southern part of the Goiás Magmatic Arc and includes a ca. 900 Ma calc-alkaline arc sequence made of volcanic rocks ranging in composition from basalts to rhyolites, metamorphosed under greenschist to amphibolite facies. Small calc-alkaline gabbro to granite sub-volcanic bodies are also recognized. The Morro do Baú intrusion is the largest of these intrusions, and is made of gabbros and diorites. Zircon grains separated from one gabbro sample and analyzed by SHRIMP I yielded the mean 206Pb/238U age of 890 +/- 8 Ma, indicating that the intrusion is roughly coeval or only slightly younger than the Arenópolis volcanics. Contrary to the metavolcanics, which are juvenile, the Nd isotopic composition of the Morro do Baú gabbro indicates strong contamination with archean sialic material (T DM of 2.8 Ga and EpsilonNd(T) of -9.7), represented in the area by an allochthonous sliver of archean/paleoproterozoic gneisses (Ribeirão gneiss) which are the country-rocks for the gabbro/dioritic intrusion. The emplacement age of ca. 890 Ma represents a minimum age limit for the tectonic accretion of the gneiss sliver to the younger rocks of the Arenópolis sequence. The data suggest that this happened early in the evolution of the Goiás Magmatic Arc, between ca. 920 and 890 Ma.

Synthetic Aperture Radar (SAR) images are being used more extensively than ever before for geoscience applications in the moist tropics. In this investigation, a RADARSAT1-1 C-HH SAR image acquired in 1998 was used for coastal mapping and land-cover assessment in the Bragança area, in the northern Brazil. The airborne GEMS 1000 X-HH radar image acquired in 1972 during the RADAM Project was also used for evaluating coastal changes occurring over the last three decades. The research has confirmed the usefulness of RADARSAT-1 image for geomorphological mapping and land-cover assessment, particularly in macrotidal mangrove coasts. It was possible to map mangroves, salt marshes, chenier sand ridges, dunes, barrier-beach ridges, shallow water morphologies and different forms of land-use. Furthermore, a new method to estimate shoreline changes based on the superimposition of vectors extracted from both sources of SAR data has indicated that the shoreline has been subjected to severe coastal erosion responsible for retreat of 32 km² and accretion of 20 km², resulting in a mangrove land loss of almost 12 km². In an application perspective, orbital and airborne SAR data proved to be a fundamental source of information for both geomorphological mapping and monitoring coastal changes in moist tropical environments.

An evolutionary model is proposed for the Caravelas strandplain. The model encompasses integration of: (i) mapping of Quaternary deposits, (ii) cartography of beach-ridge alignments and their truncations, (iii) relative sea-level history, (iv) development history of the Abrolhos coral reefs, (v) vibra-coring and (vi) C14 dating of Quaternary deposits. Seven major evolutionary stages were identified. These stages show that the strandplain has had its Quaternary evolution strongly controlled by relative sea-level changes. In addition, the development of the Abrolhos coral reefs has also played an important role in dispersion and accumulation of sediments along the coastline, causing localized inversion in longshore sediment transport.

The Fazenda Brasileiro gold mineralization is hosted by a gabbroic sill, intrusive into metavolcanicmetasedimentary rocks of the Rio Itapicuru Greenstone Belt, São Francisco Craton. The 2.05 Ga old mineralization is associated with intense shearing and hydrothermal alteration, and the host gabbro is altered to a series of rocks rich in sericite, chlorite, actinolite, carbonate and quartz. Twelve whole-rock samples of the gold mineralization, representing varied degrees of alteration, from rocks with preserved igneous textures to the ore (quartz-carbonate-sulfide-chlorite), were studied by the Sm-Nd method. All analytical points resulted in an isochron (MSWD = 1.9) indicating the age of 2142 +/- 47 Ma (1s) and Epsilon Nd (T) of +1.2. Chlorite-sericite-carbonate rich hydrothermal rocks indicate the age of 2148 +/- 57 Ma and Epsilon Nd (T) of +1.1. The positive Epsilon Nd (T) suggest limited or no contamination with older continental crust, compatible with an oceanic setting for the tholeiites. Combined withREEdata, the Sm-Nd isotopic results reveal that the hydrothermal alteration, although intense, was unable to alter significantly the Sm/Nd ratios of the original igneous rocks and did not cause important scatter of the analytical points, providing a rare example of robust behavior of the isotopic system, even under intense hydrothermal alteration.

The integrated investigation of metamorphism and zircon U-Pb SHRIMP geochronology of the Belizário ultramafic amphibolite from southernmost Brazil leads to a better understanding of the processes involved in the generation of the Encantadas Complex. Magmatic evidence of the magnesian basalt or pyroxenite protolith is only preserved in cores of zircon crystals, which are dated at 2257 ± 12 Ma. Amphibolite facies metamorphism M1 formed voluminous hornblende in the investigated rock possibly at 1989 ± 21 Ma. This ultramafic rock was re-metamorphosed at 702±21 Ma during a greenschist facies eventM2; the assemblage actinolite + oligoclase + microcline + epidote + titanite + monazite formed by alteration of hornblende. The metamorphic events are probably related to the Encantadas Orogeny (2257±12 Ma) and Camboriú Orogeny (~ 1989 Ma) of the Trans-Amazonian Cycle, followed by an orogenic event (702±21 Ma) of the Brasiliano Cycle. The intervening cratonic period (2000-700 Ma) corresponds to the existence of the Supercontinent Atlantica, known regionally as the Rio de la Plata Craton.

In the space of cubic forms of surfaces, regarded as a G-space and endowed with a natural invariant metric, the ratio of umbilic points with a negative index to those with a positive index is evaluated in terms of the asymmetry of the metric, defined here. This work contains also a section with references pertinent to umbilic points and one with a discussion of a connection of the above defined ratio with that reported in 1977 by Berry and Hannay in the domain of Statistical Physics.

Data on clutch size and hatching success of P. expansa were gathered for seven beaches traditionally used by the species and re-analyzed statistically by means of regression analysis, of the number of eggs on the number of females (or nests) and of the number of young on the number of eggs. All regressions were linear, passed through the origin and had excellent fits. Average clutch size varied from 75 to 123, and presented geographic differentiation: (i) Rio Orinoco, (ii) Rio Trombetas + Rio Branco and (iii) Rio Juruá + Rio Purus. Average hatching success was ca. 83%. In P. unifilis there was also geographic variation in clutch size, the Iquitos area showing the highest values. Hatching success of P. unifilis was uniformly high: only one sample, from Iquitos, had less than 90% success. The outstanding fit of the clutch size regressions leads one to consider egg volume variability, which was found to be high in both species, in contradiction with current optimal egg size theory.

The effects of the contents and chemical composition of the foliar epicuticular waxes of species from the caatinga (Aspidosperma pyrifolium, Capparis yco, Maytenus rigida and Ziziphus joazeiro) and cerrado (Aristolochia esperanzae, Didymopanax vinosum, Strychnos pseudoquina and Tocoyena formosa) were evaluated as to the resistance to water loss by means of an experimental device constructed for this purpose. In general, the waxes of the caatinga species investigated were more efficient against water loss than cerrado species. Increase of the thickness of the waxy deposits from 40 to 90m g.cm-2 had no significant effect on the resistance to water loss. The chemistry of the wax constituents was shown to be an important factor to determine the degree of resistance to evaporation. n-Alkanes and alcoholic triterpenes were the most efficient barriers, while hentriacontan-16-one (a ketone) and ursolic acid (an acid triterpene) revealed lowefficiency. The higher efficiency of the waxes of the leaves from caatinga species (mainly those of C. yco and Z. joazeiro) is probably accounted for the predominance of n-alkanes in their composition. The lower efficiency of the waxes of A. pyrifolium (caatinga), T. formosa and A. esperanzae (both species from the cerrado) is probably a consequence of the predominance of triterpenoids in the waxes of the two former species and hentriacontan-16-one in the latter.

No summary/description provided

Obligatory intracellular parasites such as Plasmodium sp, Trypanosoma cruzi, Toxoplasma gondii and Leishmania sp are responsible for the infection of hundreds of millions of individuals every year. These parasites can deliver antigens to the host cell cytoplasm that are presented through MHC class I molecules to protective CD8 T cells. The in vivo priming conditions of specific CD8 T cells during natural infection are largely unknown and remain as an area that has been poorly explored. The antiparasitic mechanisms mediated by CD8 T cells include both interferon-g-dependent and -independent pathways. The fact that CD8 T cells are potent inhibitors of parasitic development prompted many investigators to explore whether induction of these T cells can be a feasible strategy for the development of effective subunit vaccines against these parasitic diseases. Studies performed on experimental models supported the hypothesis that CD8 T cells induced by recombinant viral vectors or DNA vaccines could serve as the basis for human vaccination. Regimens of immunization consisting of two different vectors (heterologous prime-boost) are much more efficient in terms of expansion of protective CD8 T lymphocytes than immunization with a single vector. The results obtained using experimental models have led to clinical vaccination trials that are currently underway.

Stereological studies are more and more frequent in literature, particularly in the development/evolution, pathology, and neurosciences areas. The stereology challenge is to understand the structural inner threedimensional arrangement based on the analysis of the structure slices only showing two-dimensional information. Cavalieri and Scherle's methods to estimate volume, and Buffon's needle problem, are commented in the stereological context. A group of actions is needed to appropriately quantify morphological structures (unbiased and reproducibly), e.g. sampling, isotropic and uniform randomly sections (Delesse's principle), and updated stereological tools (disector, fractionator, nucleator, etc). Through the correct stereology use, a quantitative study with little effort could be performed: efficiency in stereology means a minimum slices sample counting (little work), low cost (slices preparation), but good accuracy. In the present text, a short review of the main stereological tools is done as a background basis to non-expert scientists.

Pterosaur remains from the Río Belgrano Formation, Santa Cruz Province, Argentina, were found close to the Estancia Río Roble, along with several ammonoids that indicate a Barremian age for those strata. The specimens (MACN-SC 3617) consist of one ulna and one element tentatively identified as a portion of a wing metacarpal. The ulna shows morphological affinities with the Pteranodontoidea (sensu Kellner 1996), particularly with the members of the Anhangueridae by having a well developed ventral crest close to the proximal articulation, and is tentatively referred to this pterosaur clade. The oldest record of the Anhangueridae, previously limited to the Aptian/Albian, is therefore extended to the Barremian. The Argentinean material is preserved in three dimensions, an unusual condition for pterosaur fossils from that country, indicating that the site situated near the Estancia Río Roble has a great potential for new and well preserved specimens.

The Passa Tempo Metamorphic Complex is one of several metamorphic complexes that form the Archean sialic crust of the southern São Francisco Craton. It encompasses hypersthene-bearing gneissic rocks, with subordinateNW- or EW-trending mafic-ultramafic bodies and granodioritic to alkali-granitic, weakly foliated, and light-colored granitoids. These granitoids are the product of generalized migmatization that followed granulite-facies metamorphism. To determine the ages of the granulite-facies metamorphism and granitoid genesis, we obtained U-Pb ages on zircon extracted from the mesosome and leucosome of the migmatitic gneisses. For the mesosome, a discordia that intercepts Concordia at 2622 ± 18 Ma is interpreted as a minimum age for granulite-facies metamorphism. For the leucosome, the upper intercept of discordia at 2599 ± 45 Ma corresponds to migmatization and granitoid genesis. Contemporaneous metamorphism and magmatism have been documented elsewhere in the São Francisco Craton, especially in the southern portion, demonstrating vast and vigorous reworking of sialic crust by the end of the Neoarchean.

Botrychiopsis has been considered an important floristic element of Westphalian/Artinskian associations of the Paraná Basin. The occurrence of Botrychiopsis in roof-shales of the Rio Bonito Formation in Southern Paraná Basin (Quitéria area), supported by the identification of Botrychiopsis valida, enlarges the genus biochron. Consequently, the stratigraphic hierarchy for Botrychiopsis plantiana and Botrychiopsis valida was defined for the Paraná Basin. Although it is climatically controlled and related to a deglaciation icehouse stage, stratigraphic distribution of the genus presents a substantial climate tolerance, from cold/cool to warm/temperate conditions. A new phytostratigraphic zonation is proposed for the southern portion of the basin that includes the Botrychiopsis Zone (Asselian/Kungurian), which is subdivided into the Botrychiopsis plantiana (Asselian/Artinskian) and Botrychiopsis valida (Late Artinskian/Kungurian) subzones.

In this paper we prove a tangency principle (see Fontenele and Silva 2001) related with the length of the second fundamental form, for hypersurfaces of an arbitrary ambient space. As geometric applications, we make radius estimates of the balls that lie in some component of the complementary of a complete hypersurface into Euclidean space, generalizing and improving analogous radius estimates for embedded compact hypersurfaces obtained by Blaschke, Koutroufiotis and the authors. The basic tool established here is that some operator is elliptic at points where the second fundamental form is positive definite.

We search for an amplification mechanism of the seed cosmic magnetic induction by studying a new version of the Dirac's æther in a curved cosmological background. We find that the variation of the scale factor R(t) with cosmic time brings to the magnetic field the desired effect of amplification, that we call geometric amplification.