545 research outputs found

    Physicochemical behavior of Riesling x Silvaner grapevine fruit under the high altitude conditions of Colombia (South America)

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    The Valle del Sol (Sun Valley) of the Boyacá department is a zone with temperate tropical climate conditions (2,500 m above sea level) that is suitable for the production of grapes for quality wine. The objective of this investigation was to study the physical and chemical behavior during growth and development of the grapevine fruit var. Riesling x Silvaner, produced for winemaking, in the municipality of Corrales (Boyacá, Colombia). To determine the physical and chemical characteristics of the fruit starting at 28 days after anthesis (daa), 14 weekly samplings were carried out, in each of which three clusters were taken from randomly selected plants. The development of the berry lasted 119 daa in which three stages were defi ned: herbaceous, veraison and maturation1. The herbaceous stage ended at 63 daa, the veraison period lasted 14 days and ended at 77 daa, whereas the maturation and ripening stage lasted 42 days; no period of overmaturity was observed. The behavior of the fresh mass, dry mass and diameter of the fruit followed a double sigmoid curve. During berry development, total soluble solids (from 5.03 to 23.73 °Brix at the harvest point), pH (from 2.88 to 3.71) and technological maturity index (from 2.27 to 21.84) all increased, whereas total titratable acidity decreased from 3.96 to 1.11%

    Thermal diffusion of supersonic solitons in an anharmonic chain of atoms

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    We study the non-equilibrium diffusion dynamics of supersonic lattice solitons in a classical chain of atoms with nearest-neighbor interactions coupled to a heat bath. As a specific example we choose an interaction with cubic anharmonicity. The coupling between the system and a thermal bath with a given temperature is made by adding noise, delta-correlated in time and space, and damping to the set of discrete equations of motion. Working in the continuum limit and changing to the sound velocity frame we derive a Korteweg-de Vries equation with noise and damping. We apply a collective coordinate approach which yields two stochastic ODEs which are solved approximately by a perturbation analysis. This finally yields analytical expressions for the variances of the soliton position and velocity. We perform Langevin dynamics simulations for the original discrete system which fully confirm the predictions of our analytical calculations, namely noise-induced superdiffusive behavior which scales with the temperature and depends strongly on the initial soliton velocity. A normal diffusion behavior is observed for very low-energy solitons where the noise-induced phonons also make a significant contribution to the soliton diffusion.Comment: Submitted to PRE. Changes made: New simulations with a different method of soliton detection. The results and conclusions are not different from previous version. New appendixes containing information about the system energy and soliton profile

    The 2-79 keV X-ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton and Chandra: a Fully Compton-Thick AGN

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    The Circinus galaxy is one of the nearest obscured AGN, making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical parameters for the obscuring material. Chandra's high angular resolution allows a separation of nuclear and off-nuclear galactic emission. In the off-nuclear diffuse emission we find signatures of strong cold reflection, including high equivalent-width neutral Fe lines. This Compton-scattered off-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton-scattering by an optically-thick torus, where the intrinsic spectrum is a powerlaw of photon index Γ=2.22.4\Gamma = 2.2-2.4, the torus has an equatorial column density of NH=(610)×1024N_{\rm H} = (6-10)\times10^{24}cm2^{-2} and the intrinsic AGN 2102-10 keV luminosity is (2.35.1)×1042(2.3-5.1)\times 10^{42} erg/s. These values place Circinus along the same relations as unobscured AGN in accretion rate-vs-Γ\Gamma and LXL_X-vs-LIRL_{IR} phase space. NuSTAR's high sensitivity and low background allow us to study the short time-scale variability of Circinus at X-ray energies above 10 keV for the first time. The lack of detected variability favors a Compton-thick absorber, in line with the the spectral fitting results.Comment: Accepted for publication in Ap

    ESTUDIO DE LA PLASTICIDAD FENOTIPICA EN CULTIVARES DE FRIJOL ARBUSTIVO INDETERMINADO (Phaseolus vulgaris L.)

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    Un experimento fue establecido en el centro investigación de Corpoica – Tibaitata para evaluar el efecto de tres distancias de siembra sobre tres genotipos de frijol tipo II de crecimiento indeterminado. Un distancia de siembra entre surco (0,60 m) y tres distancias de siembra entre plantas fueron utilizados (0,1, 0,20 y 0,30m), las cuales resultaron en poblaciones comprendidas entre 55´556 hasta 166’667 plantas. ha objetivo del estudio fue analizar el efecto de la densidad de siembra sobre los componentes de rendimiento y los rendimientos agronómico y biológico para establecer cuál de ellos es plástico. El diseño experimental fue el de parcelas divididas con tres repeticiones. Los genotipos fueron ubicados en las parcelas principales y en las subparcelas las distancias de siembra. La densidad de siembra influyo sobre los componentes de rendimiento número de vainas peso de 100 granos y el índice de cosecha. La interacción genotipo y distancias de siembra fue significativa para los rendimientos. El número de semillas por vaina no fue modificado por las distancias de siembra. El número de vainas, el peso de 100 granos y los rendimiento variaron por efecto de la distancias de siembra en forma lineal positiva en forma significativa demostrando que son plásticos  y pueden serusados para selección de genotipos. El rendimiento agronómico y biológico difirieron estadísticamente para los genotipos L34213, L (Diacol Andino x 31605) y cv ICA Tundama

    Discovery of a relation between black hole mass and soft X-ray time lags in active galactic nuclei

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    We carried out a systematic analysis of time lags between X-ray energy bands in a large sample (32 sources) of unabsorbed, radio quiet active galactic nuclei (AGN), observed by XMM-Newton. The analysis of X-ray lags (up to the highest/shortest frequencies/time-scales), is performed in the Fourier-frequency domain, between energy bands where the soft excess (soft band) and the primary power law (hard band) dominate the emission. We report a total of 15 out of 32 sources displaying a high frequency soft lag in their light curves. All 15 are at a significance level exceeding 97 per cent and 11 are at a level exceeding 99 per cent. Of these soft lags, 7 have not been previously reported in the literature, thus this work significantly increases the number of known sources with a soft/negative lag. The characteristic time-scales of the soft/negative lag are relatively short (with typical frequencies and amplitudes of \nu\sim 0.07-4 \times 10^{-3} Hz and \tau\sim 10-600 s, respectively), and show a highly significant (\gsim 4\sigma) correlation with the black hole mass. The measured correlations indicate that soft lags are systematically shifted to lower frequencies and higher absolute amplitudes as the mass of the source increases. To first approximation, all the sources in the sample are consistent with having similar mass-scaled lag properties. These results strongly suggest the existence of a mass-scaling law for the soft/negative lag, that holds for AGN spanning a large range of masses (about 2.5 orders of magnitude), thus supporting the idea that soft lags originate in the innermost regions of AGN and are powerful tools for testing their physics and geometry.Comment: 12 pages, 6 figures. Revised version, accepted for publication in MNRA

    Identificación de maderas colombianas utilizando el Xylotron: Prueba de concepto de una colaboración internacional

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    Field deployable computer vision wood identification systems can play a key role in combating illegal logging in the real world. This work used 764 xylarium specimens from 84 taxa to develop an image data set to train a classifier to identify 14 commercial Colombian timbers. We imaged specimens from various xylaria outside Colombia, trained and evaluated an initial identification model, then collected additional images from a Colombian xylarium (BOFw), and incorporated those images to refine and produce a final model. The specimen classification accuracy of this final model was ~ 97%, demonstrating that including local specimens can augment the accuracy and reliability of the XyloTron system. Our study demonstrates the first deployable computer vision model for wood identification in Colombia, developed on a timescale of months rather than years by leveraging international cooperation. We conclude that field testing and advanced forensic and machine learning training are the next logical steps.Sistemas de identificación automatizada de maderas pueden fortalecer la lucha contra el tráfico ilegal de maderas. Este trabajo utilizó 764 especímenes de xilotecas, correspondientes a 84 taxones, para desarrollar un modelo de identificación para 14 especies comerciales de Colombia. Se comenzó colectando imágenes de especímenes provenientes de xilotecas fuera de Colombia, que se utilizaron para entrenar y evaluar un modelo inicial. Se colectaron imágenes adicionales provenientes de una xiloteca Colombiana (BOFw), que se utilizaron para refinar y producir el modelo final. La capacidad de reconocimiento de este modelo fue del ~97%, demostrando que incluir muestras locales aumenta la precisión y confiabilidad del sistema [XyloTron]. Este estudio presenta el primer modelo de vision computarizada para identificación de maderas en Colombia, desarrollado en una escala de tiempo corta y bajo cooperación internacional. Concluimos que pruebas en campo y capacitación forense y en aprendizaje automatizado, son los siguientes pasos lógicos a seguir

    Hematuria vesical bovina y su relación con algunas especies vegetales.

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    Se hizo un estudio experimental con el objeto de relacionar algunas plantas con la etiología de la hematuria vesical bovina. 4 especies vegetales recolectadas y seleccionadas en una región donde existe un alto índice de hematuria fueron suministradas a ratones (Mus musculus c. swiss albino). Las especies Hydrocotyle bomnplandii, Thelipteris rudis y Thuidium peruvianum se proporcionaron a los ratones en forma de extractos acuosos, la planta Chupea racemosa, se suministró en mezcla con el concentrado. La presencia de estas 4 especies, ha sido confirmada en zonas donde se desarrolla la enfermedad. Los resultados histopatológicos, permitieron verificar el desarrollo de micro hematuria en cada uno de los grupos a los que se suministró la especie vegetal. Se efectuó el estudio fitoquímico de la especie H. bonplandii, de la cual se aislaron sustancias con propiedades químicas que pueden tener relación con la etiología de la hematuria vesical bovinaGanado de leche-Ganadería lech

    Exploring the circumstellar environment of the young eruptive star V2492 Cyg

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    Context. V2492 Cyg is a young eruptive star that went into outburst in 2010. The near-infrared color changes observed since the outburst peak suggest that the source belongs to a newly defined sub-class of young eruptive stars, where time-dependent accretion and variable line-of-sight extinction play a combined role in the flux changes. Aims. In order to learn about the origin of the light variations and to explore the circumstellar and interstellar environment of V2492 Cyg, we monitored the source at ten different wavelengths, between 0.55 \mu m and 2.2 \mu m from the ground and between 3.6 \mu m and 160 \mu m from space. Methods. We analyze the light curves and study the color-color diagrams via comparison with the standard reddening path. We examine the structure of the molecular cloud hosting V2492 Cyg by computing temperature and optical depth maps from the far-infrared data. Results. We find that the shapes of the light curves at different wavelengths are strictly self-similar and that the observed variability is related to a single physical process, most likely variable extinction. We suggest that the central source is episodically occulted by a dense dust cloud in the inner disk, and, based on the invariability of the far-infrared fluxes, we propose that it is a long-lived rather than a transient structure. In some respects, V2492 Cyg can be regarded as a young, embedded analog of UX Orionis-type stars. Conclusions. The example of V2492 Cyg demonstrates that the light variations of young eruptive stars are not exclusively related to changing accretion. The variability provided information on an azimuthally asymmetric structural element in the inner disk. Such an asymmetric density distribution in the terrestrial zone may also have consequences for the initial conditions of planet formation.Comment: 9 pages, 7 figures, 2 online tables, accepted for publication in A&

    Dissecting the long-term emission behaviour of the BL Lac object Mrk 421

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    We report on long-term multiwavelengthmonitoring of blazar Mrk 421 by the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration and Steward Observatory, and by the Swift and Fermi satellites. We study the source behaviour in the period 2007–2015, characterized by several extreme flares. The ratio between the optical, X-ray and γ -ray fluxes is very variable. The γ -ray flux variations show a fair correlation with the optical ones starting from 2012.We analyse spectropolarimetric data and find wavelengthdependence of the polarization degree (P), which is compatible with the presence of the host galaxy, and no wavelength dependence of the electric vector polarization angle (EVPA). Optical polarimetry shows a lack of simple correlation between P and flux and wide rotations of the EVPA.We build broad-band spectral energy distributions with simultaneous near-infrared and optical data from the GASP-WEBT and ultraviolet and X-ray data from the Swift satellite. They show strong variability in both flux and X-ray spectral shape and suggest a shift of the synchrotron peak up to a factor of ∼50 in frequency. The interpretation of the flux and spectral variability is compatible with jet models including at least two emitting regions that can change their orientation with respect to the line of sight.http://10.0.4.69/mnras/stx2185Accepted manuscrip
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