Effects of post-annealing on the dielectric properties of Au/BaTiO3/Pt thin film capacitors

Barium titanate thin films were prepared by the polymeric precursor method and deposited onto Pt/Ti/SiO2/Si substrates. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR) and micro-Raman spectroscopy were used to investigate the formation of the BaTiO3 perovskite phase. Afterwards, the films were submitted to post-annealing treatments in oxygen and nitrogen atmospheres at 300 degreesC for 2 h, and had their dielectric properties measured. It was observed that the electric properties of the thin films are very sensitive to the nature of the post-annealing atmosphere. This study demonstrates that post-annealing in an oxygen atmosphere increases the dielectric relaxation phenomenon and that post-annealing in a nitrogen atmosphere produces a slight dielectric relaxation. (C) 2004 Elsevier B.V All rights reserved.

Static lung compliance and body pressures in Tupinambis merianae with and without post-hepatic septum

The surgical removal of the post-hepatic septum (PHS) in the tegu lizard, Tupinambis merianae, significantly reduces resting lung volume (VLr) and maximal lung volume (VLm) when compared with tegus with intact PHS. Standardised for body mass (MB), static lung compliance was significantly less in tegus without PHS. Pleural and abdominal pressures followed, like ventilation, a biphasic pattern. In general, pressures increased during expiration and decreased during inspiration. However, during expiration pressure changes showed a marked intra- and interindividual variation. The removal of the PHS resulted in a lower cranio-caudal intracoelomic pressure differential, but had no effect on the general pattern of pressure changes accompanying ventilation. These results show that a perforated PHS that lacks striated muscle has significant influence on static breathing mechanics in Tupinambis and by analogy provides valuable insight into similar processes that led to the evolution of the mammalian diaphragm. © 2003 Elsevier Science B.V. All rights reserved.

Post-selection and return of foraged material by Acromyrmex subterraneus brunneus (Hymenoptera: Formicidae)

Two colonies of Acromyrmex subterraneus brunneus Forel (Hymenoptera: Formicidae) were studied regarding their behavior during cultivation of the fungus garden to determine a) the existence of post-selection of foraged material by the workers, and b) if present, the mechanism of this discrimination and how this material is returned. Many studies on plant processing by leaf-cutting ants have been carried out, but none of them has investigated the decision-making process of workers in the case of erroneous food selection. For this purpose, material with different degrees of moisture and hardness (floral sponge, polystyrene, plastic and clay) were individually offered to the colonies and the tasks performed by the different size categories were carefully recorded. Three tasks, i.e., foraging, cultivation of the fungus garden and return of the foraged material, were studied and subdivided into 14 subtasks. Analysis of all inert materials as a whole showed the presence of post-selection of foraged material through the return of material inadequate for the workers and the fungus. Discrimination of the inert material was observed at the time of shredding, probably based on parameters such as physical resistance to cutting and moisture content. A. s. brunneus workers showed flexibility in their activities during substrate processing. The observed post-selection of foraged material provides strong evidence for the cognitive abilities of worker ants and of the colony as a whole. Polymorphism and a complex society represent vital characteristics for the ecological success of this species.

Road segment delineation using active testing principle and an edge-based post-processing strategy

This paper presents a semi-automated method for extracting road segments from medium-resolution images based on active testing and edge analysis. The method is based on two sequential and independent stages. Firstly, an active testing method is used to extract an approximated road centreline which is based on a sequential and local exploitation of the image. Secondly, an iterative strategy based on edge analysis and the approximated centreline is used to measure precisely the road centreline. Based on the results obtained using medium-resolution test images, the method seems to be very promising. In general, the method proved to be very accurate whenever the roads are characterized by two well-defined anti-parallel edges and robust even in the presence of larger obstacles such as trees and shadows.

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.

Balance Preliminar de las Economías de América Latina y el Caribe 2003

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El complejo forestal en Argentina

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Autonomía o ciudadanía incompleta: el pueblo mapuche en Chile y Argentina

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Aportes para una estrategia PYME en la Argentina

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Lineamientos para una política PYME en la Argentina

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Buenas prácticas en política PYME: experiencia internacional y enseñanzas para la Argentina

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República Popular China: un desafío y una oportunidad para el sector agroalimentario de la República Argentina: herramientas para exportar

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Inversión extranjera directa en la Argentina: crisis, reestructuración y nuevas tendencias después de la convertibilidad

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Las PYMES argentinas en el escenario post convertibilidad: políticas públicas, situación y perspectivas

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