Some Initial Conditions for Disposed Satellites of the Systems GPS and Galileo Constellations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Field-free and field-stimulated electron emission from solids

Electron irradiation of solids produces a backemission of secondary electrons (energies between 0 and 50 eV) and reflected primaries (energies between 50 eV and that of the incident beam). For insulators, it is shown that an externally applied positive electric field penetrating into the solid material, energizes electrons generated by the primary irradiation and enables them to travel back to the surface of incidence and be emitted (stimulated secondary emission).

The use of preserved equine renal capsule to repair lamellar corneal lesions in normal dogs

The purpose of this study was to evaluate the use of equine renal capsule preserved in 98% glycerine to repair lamellar corneal lesions in normal dogs. For this purpose, 12 dogs, divided into six groups (n = 2), were used to evaluate the 1st to 7th day, 15th day and 30th to 60th postoperative day. In order to perform the histologic study, the clinical procedures were analyzed, while the recipient's corneas were collected. The photophobia and blepharospasm also were more intense in the 1st to 7th postoperative day, and regressed in the 15th postoperative day. Therefore, the edema and the vascular events were both more frequent in the intermediary phases and regressed in the late periods. On the other hand, the morphological evaluation demonstrated an inflamatory exudate, also in the intermediary and late periods. These results suggested that the equine renal preserved capsule could be a useful alternative tissue to repair lamellar corneal lesions in dogs.

Taxonomy and distribution of Paralemanea (Lemaneaceae, Rhodophyta) in Central Mexico

Three collections of Paralemanea from Central Mexico included two species. Paralemanea mexicana is large (length ≥ 4.0 cm; diameter > 400 μm) and generally branched (≥ 40 % of plants branched), with whorled branches, of first to second order. Paralemanea annulata is small (length < 5.0 cm ; diameter < 500 μm), generally unbranched (≤ 5 % of plants branched), with branches of first order. Spermatangial sori contained obovoid spermatangia, formed from cells of the outer cortical layers, extending above the thallus surface. Carpogonial branches are described for the first time in P. mexicana. They develop on lateral filaments at nodes or internodes and have ovoid to globular cells, abundantly branched at the basal portion, penetrating the cortex towards the thallus surface. Carposporophytes are sessile on the inner portion of the cortex and produce carpospores in chains of up to twelve. The 'Chantransia' stage was observed in P. mexicana. Paralemanea annulata is described for the first time from Mexico and P. mexicana is endemic from this country. Both species were collected in cold (temperature 12-16°C), acidic (pH 5.5-6.0), shallow (depth 1-60 cm) and moderate to fast flowing waters (> 35 cm s-1), in shaded or partly shaded river segments, on rocky substrata (mostly bedrock).

Conservative treatment of a radicular cyst in a 5-year-old child: A case report

The present report describes the management of a radicular cyst in a 5-year-old child. The treatment comprised extraction of the primary teeth involved followed by marsupialization. A removable appliance with a resin extension penetrating into the cystic cavity was used to help decompress the lesion. This treatment allowed rapid healing of the lesion and eruption of the permanent incisors without the need for orthodontic treatment.

GPR survey in the Taquari River, Pantanal Wetland, west-central Brazil

A pioneer GPR - Ground Penetrating Radar - survey was carried out in the Pantanal of Mato Grosso State, westcentral region of Brazil. Fieldwork acquisitions were carried out in February/2001 and August/2002 in order to understand avulsion processes that are occurring within the Taquari alluvial megafan. The main subjects were to map channel, crevasses and floodplain morphology, as well as active sedimentary bedforms. Many GPR profiles were surveyed in the medium and lower Taquari River course. Subaqueous megaripples and exposed sand bars inside the Taquari channel were identified in the medium fan area. Similar features were observed in the lower fan channels, where there are also many crevasses in the marginal levees. During the flooding seasons the flow splays out in the floodplain where new distributary channels are being formed. As shown by GPR data, in the lower fan the Taquari channel is topographically higher than the adjacent floodplain, situation in which avulsion is a natural process of river course shifting. The lack of information about river morphology and dynamics is a major strain to better understand the sediment transport and the avulsion processes in the Taquari megafan. In this context, the GPR data obtained in wet and dry seasons, integrated to sedimentological information, have been very important to characterize the fluvial dynamics and the avulsion phenomena.

Application of GPR in the study of a modern alluvial megafan: The case of the Taquari river in Pantanal wetland, West-Central Brazil

A novel and timely ground penetrating radar (GPR) survey has been carried out in Pantanal from Mato Grosso State, west-central Brazil. Fieldwork was carried out on February/2001 and August/2002 in an attempt to understand avulsion processes that are occurring within Taquari alluvial megafan. The main objectives were to map channel, crevasse and floodplain morphology, as well as active sedimentary bedforms. Many GPR profiles were acquired in the medium and lower Taquari River course. Subaqueous megaripples and exposed sand bars were identified in the medium fan area. Similar features were observed in the lower fan channels, where there were many crevasses in the marginal levees. During the flooding seasons, the flow splays out on to the floodplain, where new distributary channels are being formed. GPR data show that the lower fan, Taquari channel is topographically higher than the adjacent floodplain, thus favoring avulsion as a natural process of river course shifting. GPR data obtained during the wet and dry seasons, together with sedimentology information have been very important in characterizing the fluvial dynamics, and avulsion phenomena. © 2005 Springer Science+Business Media, Inc.

Solid particles in the tropical lowest stratosphere

We report in situ and remote observations proving occasional occurrence of solid particles in the tropical lowest stratosphere, 200km from deep convective events. The particles were found during field campaigns in Southeast Brazil (49.03 W 22.36 S). They occur in the altitude range from 17.5 to 20.8 km, at temperatures up to at least 10 K above the expected frost point temperature. While stability of ice particles at these altitudes is unexpected from a theoretical point of view, it is argued that these observations are indications of tropospheric air masses penetrating into the stratosphere during convective overshoots. It is argued that the intrusion of tropospheric air must have carried a large amount of water with it, which effectively hydrated the lowest stratosphere, and consequently suppressed sublimation. This conclusion is further supported by a separate water vapor mixing ratio profile obtained at the same observation site.

In vitro evaluation of surface roughness of 4 resin composites after the toothbrushing process and methods to recover superficial smoothness.

OBJECTIVE: This study evaluated the efficiency of repolishing, sealing with surface sealant, and the joining of both in decreasing the surface roughness of resin-based composites after a toothbrushing process. METHOD AND MATERIALS: Ten specimens of each composite (Alert, Z100, Definite, and Prodigy Condensable), measuring 2 mm in thickness and 4 mm in diameter, were made and submitted to finishing and polishing processes on both sides of the specimens using the Sof-Lex system. The specimens were then subjected to toothbrushing (30,000 cycles), and surface roughness (Ra) was analyzed with a Surfcorder SE 1700 profilometer. The upper surface of each composite was etched with 37% phosphoric acid, and the surface-penetrating sealant Protect-it was applied on 1 surface. The roughness of these surfaces was again measured. On the other side, the surface of the specimen was repolished, and the efficiency of this procedure was measured using the profilometer. The surface roughness resulting from the joining of the 2 methods was verified by applying, in the final stage, the surface-penetrating sealant on the repolished surface. Data were analyzed with analysis of variance and Tukey test (P <.05). RESULTS: Results showed that the lowest surface roughness values were obtained for Definite, Z100, and Prodigy Condensable after the repolishing process and after the repolishing plus sealing. For Alert, the joining of repolishing plus sealing promoted the lowest values of surface roughness. CONCLUSION: Of the resin-based composites, Alert demonstrated the highest values of surface roughness in all the techniques tested.

Use of fibrin glue derived from snake venom in the repair of deep corneal ulcers - Experimental study in dogs (Canis familiaris, Linnaeus, 1758)

Fibrin glue has been researched as an alternative method for tissue synthesis and is known for its capability to promote hemostasis at the application site, good approximation of wound edges and fast healing. The current study consisted in the application of fibrin glue derived from snake venom as treatment for experimental corneal ulcers. Twenty-one dogs had their corneas experimentally prepared through lamellar keratectomy (of standardized diameter and depth). Animals were divided into seven groups of three animals each. Six experimental groups were periodically evaluated and collection was carried out on the 1st, 3rd, 7th, 15 th, 30th and 60th post-operative days, whereas one control group was evaluated throughout the experiment. Analyses consisted in the clinical evolution and in the histopathological study of all operated on eyes. Results indicated that fibrin glue was efficient in repairing keratectomy wounds in dogs and contributed to an earlier healing phenomenon, avoiding edema formation and keeping corneal clearness. The use of fibrin glue derived from snake venom showed to be easy to apply, feasible with animal models and of low cost, avoiding the lesion progress and allowing fast and appropriate corneal healing.

Endovascular treatment of pseudoaneurysm of the thoracic aorta from a firearm injury

A 24-year-old male patient was the victim of a firearm wound that penetrated the thorax. He arrived at another hospital hemodynamically unstable and was submitted to exploratory surgery by means of bithoracotomy. A lesion of the left branch of the pulmonary artery was detected and successfully repaired. He was submitted for computer-aided tomography on the fifth postoperative day, and a lesion of the mid-thoracic aorta was detected, which formed a saccular image. Considering that the patient had already been submitted to a bithoracotomy and that a direct approach to repair would involve another thoracotomy within a short period of time, endovascular treatment was chosen in our hospital. The procedure was performed under fluoroscopy. A second computer-aided tomography indicated adequate treatment of the lesion, with no indication of an endoleak. He has undergone ambulatory follow-up for 36 months without any problem related to the procedure. While endovascular treatment of the aorta has developed enormously, multicenter studies are needed to better define the long-term results of this approach. © 2008 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.

Marine catfish sting causing fatal heart perforation in a fisherman

Many marine catfish have serrated bony stings (spines), which are used in defense against predators, on the dorsal and pectoral fins. While catfish-induced injuries are generally characterized by the pain associated with envenomation, the stings in some species are sufficiently long and sharp to cause severe penetrating trauma. Most injuries are to the hands of victims, commonly fishermen. We report the death of a fisherman caused by myocardial perforation from a catfish sting. To our knowledge, this is the first such description in the medical literature.

Abnormal evening vertical plasma drift and effects on ESF and EIA over Brazil-South Atlantic sector during the 30 October 2003 superstorm

Equatorial F region vertical plasma drifts, spread F and anomaly responses, in the south American longitude sector during the superstorm of 30 October 2003, are analyzed using data from an array of instruments consisting of Digisondes, a VHF radar, GPS TEC and scintillation receivers in Brazil, and a Digisonde and a magnetometer in Jicamarca, Peru. Prompt penetrating eastward electric field of abnormally large intensity drove the F layer plasma up at a velocity ∼1200 ms -1 during post dusk hours in the eastern sector over Brazil. The equatorial anomaly was intensified and expanded poleward while the development of spread F/plasma bubble irregularities and GPS signal scintillations were weaker than their quiet time intensity. Significantly weaker F region response over Jicamarca presented a striking difference in the intensity of prompt penetration electric field between Peru and eastern longitudes of Brazil. The enhanced post dusk sector vertical drift over Brazil is attributed to electro-dynamics effects arising energetic particle precipitation in the South Atlantic Magnetic Anomaly (SAMA). These extraordinary results and their longitudinal differences are presented and discussed in this paper. Copyright 2008 by the American Geophysical Union.

From industrial economics to digital economics: an introduction to the transition

Includes bibliography

Latin America on its path into the digital age: where are we?

Includes bibliography