Browsing by Author "Perez, Felipe"

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    Establishment of Monterrey Pine (Pinus radiata) Plantations and Their Effects on Seasonal Sediment Yield in Central Chile
    (2023) Pizarro, Roberto; Garcia-Chevesich, Pablo; Ingram, Ben; Sanguesa, Claudia; Pino, Juan; Ibanez, Alfredo; Mendoza, Romina; Vallejos, Carlos; Perez, Felipe; Flores, Juan Pablo; Vera, Mauricio; Balocchi, Francisco; Bustamante-Ortega, Ramon; Martinez, Gisella
    Sediment production and transport in a basin are generally a function of the degree of soil protection, normally represented by plant cover. In this study, two basins located at similar latitudes but with different hydrological regimens and plant covers were studied, one with a pluvial regimen and forest plantations (Purapel) and another one with the pluvio-nival regimen and native forest (Nuble). For this purpose, sediment yield was analyzed in both drainage areas using the Mann-Kendall statistical test. Both basins showed larger amounts of sediment production during winter months. In addition, sediment yield trends did not show significant variation in the case of the Nuble, most likely due to non-relevant changes in plant cover over time. However, there is a sustained decrease in annual sediment release at Purapel, coinciding with the afforestation in the basin, so it is logical to attribute the referred reduction to this process. For the first time, the behavior of two watersheds is contrasted, one covered with native forest and the other one with forest plantations, appreciating that the basin covered with plantations presents a reduction in sediment production over time, which means that forest plantations are efficient in sediment retention, even in contrast to native forest. However, both basins have different types of soil, topography, etc., meaning that more studies are needed to support this theory.
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    Millimagnitude photometry for transiting extrasolar planetary candidates.: II. transits of OGLE-TR-113-B in the optical and near-ir
    (2007) Diaz, Rodrigo F.; Ramirez, Sebastían; Fernandez, José Miguel; Gallardo, José; Gieren, Wolfgang; Ivanov, Valentin D.; Mauas, Pablo; Minniti, Dante; Pietrzynski, Grzegorz; Perez, Felipe; Ruiz, Maria Teresa; Udalski, Andrzej; Zoccali, Manuela
    We present precise V-and K-s-band transit photometry for the planetary host star OGLE-TR-113. Using the Ks-band photometry, we confirm the dwarf nature of OGLE-TR-113 and obtain new estimates for its effective temperature, distance, and reddening. We employ the V-band photometry to obtain planetary and orbit parameters from the transit fit, alpha = 0.0232 +/- 0: 0038 AU, orbital period P = 1.4324752 +/- 0.0000015 day, i = 86.7-90, and R-p 1.09 +/- 0.09 R-J. These values are in excellent agreement with previous works. Assuming a mass M-p 1.32 +/- 0.19 M-J for the planet, we obtain its mean density p = 1.26 +/- 0.50 g cm(-3), also in agreement with previous works. The transit observed in the K-s-band has a larger scatter, and we find its amplitude to be consistent with that in the V band. In this way, we find an independent confirmation of the planetary nature of OGLE-TR-113b.