2,047 research outputs found

    Estimación de área foliar utilizando técnicas de procesamiento de imágenes: una metodología simple, fiable y de bajo costo

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    En este trabajo se propone una metodología para estimar área foliar (AF), basada en técnicas de procesamiento digital de imágenes usualmente utilizadas en teledetección. La metodología se evaluó para hojas de girasol. El AF y el ampliamente difundido índice de área foliar (IAF), calculado a partir del anterior, se requieren para modelar, validar y predecir un número importante de variables de interés en distintas áreas del conocimiento. Se analizan en este trabajo todas las etapas, desde la adquisición de las imágenes a los métodos de procesa-miento, así como la evaluación de la fiabilidad del método y, se diseñó, con especial detalle, una sección orientada a cuantificar adecuadamente la incertidumbre en la determinación del AF. El método propuesto es simple y robusto, las imágenes pueden adquirirse con cualquier cámara disponible y, para la estimación de superficie, pueden utilizarse una variedad de paquetes de software tanto comerciales como libres. La incerteza obtenida para la determinación del AF resultó inferior al 4% en la estimación de AF por planta. Cabe mencionar que todo el proceso se realiza a partir de las imágenes sin necesidad de datos del cultivo, climáticos, etc. Se proponen también alternativas semiautomáticas para la estimación de superficies que no presentan diferencias estadísticamente significativas con el diseño original.Sociedad Argentina de Informática e Investigación Operativ

    Influence of soil variables at the L Band: backscattering coefficient simulations for sunflower in early stages

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    SAR backscattering coefficient (σ⁰) of crops depends on the operational frequency, polarization and incidence angle of the acquisition system, the dielectric behaviour of crops, and soil-related variables such as the volumetric moisture (mv) and its roughness. In SAR applications, surface roughness is usually characterized by two parameters: the standard deviation of the surface height to a reference height or rms height (s) and the autocorrelation length. The autocorrelation length, defined as the distance at which the correlation function drops to 1/e, describes the surface periodicity and indicates to what extent two separate points can be considered correlated. For crops in their early stages, soil characteristics play a crucial role in σ⁰ due to the low vegetation development. In this work, we present σ⁰ simulations for sunflower (early stages) using a model proposed by for the L Band; specifically, the frequency was set to that of the SAOCOM instruments (1.275 GHz).Sociedad Argentina de Informática e Investigación Operativ

    Recovery of dialysis patients with COVID-19 : health outcomes 3 months after diagnosis in ERACODA

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    Background. Coronavirus disease 2019 (COVID-19)-related short-term mortality is high in dialysis patients, but longer-term outcomes are largely unknown. We therefore assessed patient recovery in a large cohort of dialysis patients 3 months after their COVID-19 diagnosis. Methods. We analyzed data on dialysis patients diagnosed with COVID-19 from 1 February 2020 to 31 March 2021 from the European Renal Association COVID-19 Database (ERACODA). The outcomes studied were patient survival, residence and functional and mental health status (estimated by their treating physician) 3 months after COVID-19 diagnosis. Complete follow-up data were available for 854 surviving patients. Patient characteristics associated with recovery were analyzed using logistic regression. Results. In 2449 hemodialysis patients (mean ± SD age 67.5 ± 14.4 years, 62% male), survival probabilities at 3 months after COVID-19 diagnosis were 90% for nonhospitalized patients (n = 1087), 73% for patients admitted to the hospital but not to an intensive care unit (ICU) (n = 1165) and 40% for those admitted to an ICU (n = 197). Patient survival hardly decreased between 28 days and 3 months after COVID-19 diagnosis. At 3 months, 87% functioned at their pre-existent functional and 94% at their pre-existent mental level. Only few of the surviving patients were still admitted to the hospital (0.8-6.3%) or a nursing home (∼5%). A higher age and frailty score at presentation and ICU admission were associated with worse functional outcome. Conclusions. Mortality between 28 days and 3 months after COVID-19 diagnosis was low and the majority of patients who survived COVID-19 recovered to their pre-existent functional and mental health level at 3 months after diagnosis

    Search for massive resonances decaying in to WW,WZ or ZZ bosons in proton-proton collisions at root s=13 TeV

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    CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

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    CMB-S4---the next-generation ground-based cosmic microwave background (CMB) experiment---is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semi-analytic projection tool, targeted explicitly towards optimizing constraints on the tensor-to-scalar ratio, rr, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2--3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments given a desired scientific goal. To form a closed-loop process, we couple this semi-analytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r>0.003r > 0.003 at greater than 5σ5\sigma, or, in the absence of a detection, of reaching an upper limit of r<0.001r < 0.001 at 95%95\% CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note: text overlap with arXiv:1907.0447

    Measurement of prompt and nonprompt J/psi production in pp and pPb collisions at root s(NN)=5.02 TeV

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    Search for long-lived charged particles in proton-proton collisions at root s=13 TeV

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    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis
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