Browsing by Author "Lopez, P."
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- ItemEnzymatic browning in sliced and pureed avocado: A fractal kinetic study(ELSEVIER SCI LTD, 2011) Quevedo, R.; Ronceros, B.; Garcia, K.; Lopez, P.; Pedreschi, F.Modelling of browning is essential to evaluate the effectiveness of the processes applied to obtain fresh-appearance foods and also to determine their shelf life. Computer vision and the fractal kinetic method were used to quantify browning in three avocado cultivars. Samples (avocado slices and pur e) were stored at 4 degrees C and surface images were captured in the tiff format. Browning kinetic was derived from images using the L* mean method and the fractal method. In another experiment, inhibitor kinetic was also quantified, using the polyphenol oxidase activity method (in puree samples) with 0.1%, 0.5% and 1% of sodium bisulfite. In the results for avocado slices, kinetic rate derived by the fractal kinetic method was higher than that obtained with the L* mean method, but the opposite was observed when the avocado was pulping (avocado puree). Kinetic quantified by the fractal method was similarly inhibited by bisulfite, when compared with the L* mean value or PPO activity value methods. In general, the fractal method can be used to record browning kinetic and to discriminate between avocado cultivars, initial structural state of the sample (slice or puree), or in experiments using browning inhibitors. (C) 2011 Elsevier Ltd. All rights reserved.
- ItemSupernova 2012bu in NGC 3449 = Psn J10525661-3256071(2012) Howerton, S.; Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan , Marcio; McNaught, R. H.; Garradd, G.; Beshore, E. C.; Larson, S. M.; Christensen, E.; Elenin, L.; Morrell, N.; Lopez, P.; Lira, P.; Pignata, G.; Bufano, F.Report the discovery of an apparent supernova in public images from the Siding Spring Survey (SSS). SN 2012 UT R.A. (2000.0) Decl. Mag. Offset 2012bu Jan. 16.69 10 52 56.61 -32 56 07.1 18.4 37".2 E, 27".7 S The variable was designated PSN J10525661-3256071 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2012bu based on the spectroscopic confirmation reported below. Further CCD magnitudes for 2012bu: 2010 June 26.40 UT, [19.2 (SSS); 2012 Jan. 18.436, 17.9 (Joseph Brimacombe, Cairns, Australia; 51-cm RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position end figures 56s.53, 07".7); 18.45, 18.3 (L. Elenin, Lyubertsy, Russia; remotely taken at the ISON-NM Observatory near Mayhill with a 0.45-m f/2.8 telescope; position end figures 56s.52, 07".7; UCAC3 reference stars; limiting mag about 20.0). The image by Brimacombe is posted at the following website URL: http://www.flickr.com/photos/43846774@N02/6722843895/. N. Morrell, Las Campanas Observatory; P. Lopez and P. Lira, Universidad de Chile; and G. Pignata and F. Bufano, Universidad Andres Bello, report that an optical spectrogram (range 370-910 nm) of PSN J10525661-3256071 = SN 2012bu, obtained on Mar. 30.14 UT with the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory, shows it to be a type-II supernova. Adopting a recession velocity of 3274 km/s for NGC 3449 (Theureau et al., 1998, A.Ap. Suppl. 130, 333; via NED), the best fits to this spectrum found by GELATO (Harutyunyan et al. 2008, A.Ap. 488,383; publicly available at website URL https://gelato.tng.iac.es) is with spectra of evolved type-II-plateau supernovae.