Browsing by Author "Moreno, J"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Breeding biology of the Thorn-tailed Rayadito (Furnariidae) in south-temperate rainforests of Chile
    (2005) Moreno, J; Merino, S; Vásquez, RA; Armesto, JJ
    We conducted a study of the breeding biology of the Thorn-tailed Rayadito (Aphrastura spinicauda) in secondary forests on the continental island of Chiloe (42degreesS), southern Chile. Rayaditos are small insectivorous furnariids inhabiting the south-temperate forests of Chile and Argentina. We followed the reproduction of rayadito pairs breeding in nest-boxes. Rayaditos build their nests mainly of rhizomes and stems of epiphytic vines, grasses, and hairs during periods of at least a week, and show a marked population asynchrony in laying dates of more than two months (October-December). Rayaditos lay clutches of 3-6 eggs with a mode of 4 and laying occurs on alternate days. Eggs are 50% larger and hatchlings are 30% larger than expected from allometric equations. Most broods hatch synchronously. Nestling growth curves adjust well to logistic functions and at 2 weeks nestlings attain masses similar to asymptotic values. Nestling growth, which occurs over 3 weeks, is 27% slower than expected from allometry. Fledglings attain adult size with respect to tarsus length, but have less developed plumage and higher body mass than adults. Rayaditos exhibit clutch and brood reduction, suggesting possible food limitation. The protracted breeding periods may preclude second breeding attempts for most pairs in Chiloe. There is evidence for declines in parental quality with season. The low seasonal fecundity, large eggs, and prolonged dependence periods of a truly south-temperate species like the Thorn-tailed Rayadito reflect a 'slow' life history similar to that of tropical passerines.
  • No Thumbnail Available
    Item
    Further statistical studies of ionization growth and breakdown formation mechanisms in the final breakdown phase of a transient hollow cathode discharge
    (2002) Moreno, J; Zambra, M; Favre, M
    A Transient Hollow Cathode Discharge (THCD) is a high-voltage low-pressure discharge, which is characterized by an axial hollow in the cathode electrode. The temporal sequence of the different parts of ionization growth in breakdown formation, which take place just before electric breakdown, are statistically studied. The von Lane formalism has been used to characterize in detail the statistical time distribution of the different processes required for electric breakdown to occur. The experiments have been performed in Hydrogen at pressure between 13.3 and 53.2 Pa, with different sizes of the cathode aperture. It has been found that the different processes of ionization growth and breakdown formation mechanisms involved in the sequence leading to breakdown are not associated with a single characteristic time. Time-shifted Gaussian distribution functions have been Identified which, when added together, reproduce the cumulative time distribution for each observed event, especially at low pressure and smaller cathode aperture, where the hollow cathode effect is less effective.
  • Thumbnail Image
    Item
    Synthesis and characterization of polyarylureas. I. Potentially semiconducting polymers
    (WILEY-BLACKWELL, 2001) Diaz, FR; Godoy, A; Moreno, J; Bernede, JC; Sanchez, CO; Opazo, A; Gargallo, L
    Polyarylureas were synthesized from the reaction between phosgene with aromatic diamines. Depending on the pH, the polyarylureas presented different colors when the solvent used was pyridine. The polyarylureas were characterized by IR spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy (XPS). To study the thermal stability of the polymers, a thermal degradation was performed between 35 and 700 degreesC. The polyarylureas decomposed above 350 degreesC. Without doping, polyarylureas are considered as semiconductors [sigma = 10(-9) (Omega cm)(-) (1)]; after doping with I-2, their electrical conductivity increases by several orders of magnitude. (C) 2001 John Wiley & Sons, Inc.