Browsing by Author "Gomez, M"

Now showing 1 - 8 of 8
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    Analysis of volatile compounds in three unifloral native Chilean honeys
    (2009) Montenegro Rizzardini, Gloria; Gomez, M; Casaubon, G; Belancic Majcenovic, Andrea Ángela; Mujica Rizzardini, Ana María; Pena, RC
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    BV(RI)C photometry of Cepheids in the Magellanic Cloud
    (1998) Moffett, TJ; Gieren, WP; Barnes, TG; Gomez, M
    We report BT/(RI)(C) data for a select group of 14 Cepheids in the Large Magellanic Cloud and eight in the Small Magellanic Cloud that have preexisting radial velocity curves. The photometry was obtained as part of a program to determine distances to these Cepheids by means of the visual surface brightness technique and to improve significantly the optical BV(RI)(C) light curves of Magellanic Cloud Cepheids. The data were acquired on the 0.9 m telescope at Cerro Tololo Inter-American Observatory with the CFCCD instrument and with the 1 m photometric telescope at ESO using aperture photometry. The median number of measures per Cepheid is 46 in each band, and the uncertainty in the photometry is typically +/-0.01 mag. Using these data together with data from the literature, we determined improved periods for all variables. For most of the Cepheids, these revised periods lead to excellent, low-noise light curves, but for a few variables, the periods are obviously variable.
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    Cepheid period-radius and period-luminosity relations and the distance to the large Magellanic Cloud
    (1998) Gieren, WP; Fouque, P; Gomez, M
    We have used the infrared Barnes-Evans surface brightness technique to derive the radii and distances of 34 Galactic Cepheid variables. Radius and distance results obtained from both versions of the technique are in excellent agreement. The radii of 28 variables are used to determine the period-radius (PR) relation. This relation is found to have a smaller dispersion than in previous studies, and is identical to the PR relation found by Laney & Stobie from a completely independent method, a fact which provides persuasive evidence that the Cepheid PR relation is now determined at a very high confidence level. We use the accurate infrared distances to determine period-luminosity (PL) relations in the V, I, J, H, and K passbands from the Galactic sample of Cepheids. We derive improved slopes of these relations from updated LMC Cepheid samples and adopt these slopes to obtain accurate absolute calibrations of the PL relation. By comparing these relations to the ones defined by the LMC Cepheids, we derive strikingly consistent and precise values for the LMC distance modulus in each of the passbands that yield a mean value of mu(0)(LMC) = 18.46 +/- 0.02.
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    Fire regimes and vegetation responses in two Mediterraneanclimate regions
    (2004) Montenegro Rizzardini, Gloria; Ginocchio Cea, Rosanna; Segura, A; Keely, JE; Gomez, M
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    Gibberellic acid stimulation of isoperoxidase from pedicel of grape
    (1998) Pérez, FJ; Gomez, M
    Soluble peroxidase activity from pedicels of cv. Thompson seedless grape was highly stimulated by post-bloom gibberellic acid (GA(3)) applications to vines. This stimulation was dependent on the dose employed and increased with berry ripening. In control vines, i.e. non GA(3) treated, the level of peroxidase activity remained constant during; berry ripening. Isoelectrofocusing (IEF) analysis of soluble peroxidases from pedicel extracts performed ina 3-10 pH range, showed the presence of a main band that corresponded to an acidic isoperoxidase of (pI 3.5) and the presence of a minor band of (pI 3.9). It is a well-known fact that GA, applications to cv. Thompson seedless grape beside producing berry enlargement cause berry-drop which has been associated with pedicel thickening. Here we found a positive correlation between pedicel thickness and peroxidase activity within the rates of GA, used. The involvement of the acidic isoperoxidases in pedicel thickening and its relation to berry-drop are discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.
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    Mechanisms towards a sustainable use of Chorizanthe vaginata Benth. var. maritima Remy: a medicinal plant from Chile
    (FUNDACION ROMULO RAGGIO, 2001) Gloria, M; Patrick, G; Echenique, P; Gomez, M; Timmermann, B
    Regeneration of Chorizanthe vaginata Benth. var. maritima Remy, a medicinal plant intensively traded in Chile, was analyzed to address the potential for sustainable harvest. We analyzed individual productivity per season, extrapolated results to four populations. We visited collecting sites with harvesters from a traditional market in Santiago and learned traditional collecting procedure. Relative species cover in four sites of the coastal scrub was measured to obtain estimates of remaining biomass until November 1998. Results show that plants are able to regenerate in about three years when cut above the site of the buds in the root-crown. More than 50% of plants are harvested unsustainably, and are usually between the ages of 8 and 12 years. Around 3.44 tons of C. vaginata were available in four populations. Since 5 tons are traded per year, C. vaginata is in danger of disappearing, unless proper harvesting and cultivation in degraded areas starts, as proposed by our group.
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    Very accurate distances and radii of open cluster Cepheids from a near-infrared surface brightness technique
    (1997) Gieren, WP; Fouque, P; Gomez, M
    We have obtained the radii and distances of 16 galactic Cepheids supposed to be members in open clusters or associations using a new optical and two near-infrared calibrations of the surface brightness (Barnes-Evans) method. We find excellent agreement of the radii and distances produced by both infrared techniques, which use the V, V-K (K on the Carter system) and the K, J-K magnitude-color combinations, respectively, with typical random errors that are as little as similar to 2%. We discuss possible systematic errors in our infrared solutions in detail and conclude that the typical total uncertainty of the infrared distance and radius of a Cepheid is about 3% in both infrared solutions, provided that the data are of excellent quality and that the amplitude of the color curve used in the solution is larger than similar to 0.3 mag. The optical V, V-R distance and radius of a given Cepheid can deviate by as much as similar to 30% from the infrared value because of large systematic and random errors caused by microturbulence and gravity variations: these affect the optical but not the infrared colors.