9,358 research outputs found

    The blue sky of GJ3470b: the atmosphere of a low-mass planet unveiled by ground-based photometry

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    GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a nearby M1.5 dwarf. It is of crucial interest for atmospheric studies because it is one of the most inflated low-mass planets known, bridging the boundary between "super-Earths" and Neptunian planets. We present two new ground-based light curves of GJ3470b gathered by the LBC camera at the Large Binocular Telescope. Simultaneous photometry in the ultraviolet (lambda_c = 357.5 nm) and optical infrared (lambda_c = 963.5 nm) allowed us to detect a significant change of the effective radius of GJ3470b as a function of wavelength. This can be interpreted as a signature of scattering processes occurring in the planetary atmosphere, which should be cloud-free and with a low mean molecular weight. The unprecedented accuracy of our measurements demonstrates that the photometric detection of Earth-sized planets around M dwarfs is achievable using 8-10m size ground-based telescopes. We provide updated planetary parameters, and a greatly improved orbital ephemeris for any forthcoming study of this planet.Comment: 8 pages, 6 figures, 1 table; accepted for publication in A&

    Stolon Mass and Classes in White Clover (\u3ci\u3eTrifolium repens\u3c/i\u3e L.) with Two Soil Water Availability Levels

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    Two trials were carried out to study the stolon mass and classes in white clover (Trifolium repens L.) under two soil water availability levels in summer. In each trial, treatments were two white clover cultivars. From December 15th to February 15th in 1993/94 and again during the same period the following year, white clover was grown under 30 to 70 % (Forced water uptake) or 85-to100 % (Maximum water uptake) of field capacity. Every two months, throughout two years, total stolon mass, and buried, superficial, and aerial stolons were measured. Differences between cultivars were detected in stolon mass and percentage of each stolon class in both trials

    Stolon Growth and Its Morphological Components in White Clover (\u3ci\u3eTrifolium repens\u3c/i\u3e L.) Cultivars

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    A trial was performed to study the seasonal changes in stolon growth and its morphological components in four white clover cultivars, in the north of Buenos Aires Province, in Argentina. Stolons were tagged in four seasonal measurements periods per year, during two consecutive years. Leaf, stolon and flowerheads weights were recorded at regular intervals in each measurement period and total stolon growth was calculated. Differences among cultivars were found in stolon growth and its morphological components in most of the measurement periods. In spring and summer, differences among cultivars in stolon growth were related to flowering quantity and earliness, and cultivar response to the environment. In autumn and winter, differences were associated to the ability of cultivars to grow at low temperatures

    Markov Chain Beam Randomization: a study of the impact of PLANCK beam measurement errors on cosmological parameter estimation

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    We introduce a new method to propagate uncertainties in the beam shapes used to measure the cosmic microwave background to cosmological parameters determined from those measurements. The method, which we call Markov Chain Beam Randomization, MCBR, randomly samples from a set of templates or functions that describe the beam uncertainties. The method is much faster than direct numerical integration over systematic `nuisance' parameters, and is not restricted to simple, idealized cases as is analytic marginalization. It does not assume the data are normally distributed, and does not require Gaussian priors on the specific systematic uncertainties. We show that MCBR properly accounts for and provides the marginalized errors of the parameters. The method can be generalized and used to propagate any systematic uncertainties for which a set of templates is available. We apply the method to the Planck satellite, and consider future experiments. Beam measurement errors should have a small effect on cosmological parameters as long as the beam fitting is performed after removal of 1/f noise.Comment: 17 pages, 23 figures, revised version with improved explanation of the MCBR and overall wording. Accepted for publication in Astronomy and Astrophysics (to appear in the Planck pre-launch special issue

    Seasonal Variation of White Clover Morphology at the North of Buenos Aires Province, Argentine

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    In order to study the seasonal variation in morphological characters that contribute to forage production in white clover (Trifolium repens L.) cultivars, a trial was conducted at Pergamino Agricultural Experimental Station INTA located north of Buenos Aires province, Argentina. The experimental plots were set out in a completely randomized design with four replicates. Measurements were performed over eight seasons throughout two years. The used cultivars had been previously reported as having differences in seasonal productivity. Significant differences were detected among seasons for all measured characters i.e. stolon length, number of buds, branches and leaves, and leaf area. Differences among cultivars in almost all the season were only found for leaf area and stolon length. The growth in length of stolons kept a consistent pattern in both years. No cultivar produced vegetative buds during summers. The characters most affected by environmental stress were bud and branch development

    “Using digital media or sleeping … that is the question”. A meta-analysis on digital media use and unhealthy sleep in adolescence

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    This systematic review with meta-analysis aims to examine the relation between different aspects of digital media use and sleep health patterns. Eligible studies had to be longitudinal and with adolescents' sample. Multiple search strategies were applied until January 28, 2023 in order to identify relevant research published in peer-reviewed journal articles or available grey literature. A final set of 23 studies (N = 116,431; 53.2% female; Mage at baseline = 13.4 years) were included. The quality of the studies, assessed with an adapted version of the Newcastle-Ottawa Scale, was high with a consequent low risk of bias. Meta-analytic results showed that tradi-tional media use (r =-0.33 [-0.44;-0.22]), social media use (r =-0.12 [-0.22;-0.01]), prolonged use (r = -0.06 [-0.11;-0.01]), and dysfunctional use (r =-0.19 [-0.29;-0.09]) are negatively related to adolescents' sleep health at a later time point. Conversely, sleep patterns were not related to social media use (r =-.05 [-0.10; 0.00]) and utilization time (r =-0.13 [-0.30; 0.04]), but they were related to dysfunctional use of media (r = -0.22 [-0.33; -0.10]). Overall, this review highlights the presence of a vicious cycle between digital media use and sleep health in adolescence

    Stolon Attributes Related to Persistence of White Clover in Buenos Aires, Argentina

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    A trial was carried out at Pergamino Agricultural Experimental Station (33º 56’ S, 60º 33’ W), Argentina, to study the stolon morphology of white clover cultivars with different leaf size, inflorescence production through reproductive cycle, and vegetative persistence. Treatments were four white clover cultivars: Espanso (Italy), Experimental L.49 (Argentina), Jacui S2 (Brazil) and Nora (Sweden). A completely randomized block design was used (n=6). Throughout two years, measurements of stolon length and dry and organic matter were performed every 60 days. The inflorescence number was also recorded. Results showed significant differences among cultivars in all the studied characters and almost in all the samples dates. Stolon weight showed a close association with stolon size, and the latter with the vegetative persistence (r=0.90). Stolon weight, chiefly related to stolon size, is a major character to be considered to improve white clover vegetative persistence in our region. Poor inflorescence production was not strictly associated with a better vegetative persistence

    Estimation Of Loss Probability In Gaussian Queues

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    We discuss the application of the simulation to estimate the loss probability in a queueing system with a finite buffer, which is fed by a Gaussian input. Such estimation is based on known approximation, but less known than estimation of the overflow probability in an infinite buffer system. We focus on queues with fractional Brownian input (fBi) and Brownian input (Bi). For the Bi, regenerative simulation is applied to analyze the accuracy of the analytical approximation. This work is supported by Russian Foundation for Basic research, project No 10-07-00017

    A Gaussian approximation of the distributed computing process

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    The authors propose a refinement of the stochastic model describing the dynamics of the Desktop Grid (DG) project with many hosts and many workunits to be performed, originally proposed by Morozov et al. in 2017. The target performance measure is the mean duration of the runtime of the project. To this end, the authors derive an asymptotic expression for the amount of the accumulated work to be done by means of limit theorems for superposed on-off sources that lead to a Gaussian approximation. In more detail, depending on the distribution of active and idle periods, Brownian or fractional Brownian processes are obtained. The authors present the analytic results related to the hitting time of the considered processes (including the case in which the overall amount of work is only known in a probabilistic way), and highlight how the runtime tail distribution could be estimated by simulation. Taking advantage of the properties of Gaussian processes and the Conditional Monte-Carlo (CMC) approach, the authors present a theoretical framework for evaluating the runtime tail distribution

    Evaluation and Utilization of a Tall Fescue Germplasm Collection at Pergamino INTA, Argentina

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    One hundred and fifty four accessions of tall fescue (Festuca arundinacea Schreb.) representing different types grown around the world were evaluated at Pergamino Inta Experimental Station. A multivariate analysis was carried out to evaluate individual and group variations. Three principal components (PCs) explained 70 % of the variation. Cluster analysis (Ward method) allowed the identification of 7 groups of populations. Plants from the most promising populations were selected in order to form a new breeding gene pool. The main objective of this study is to develop a new cultivar with improved winter herbage yield. Selected genotypes were mostly of Mediterranean origin
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