3,687 research outputs found

    Penalized function-on-function partial leastsquares regression

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    This paper deals with the "function-on-function'" or "fully functional" linear regression problem. We address the problem by proposing a novel penalized Function-on-Function Partial Least-Squares (pFFPLS) approach that imposes smoothness on the PLS weights. Our proposal introduces an appropriate finite-dimensional functional space with an associated set of bases on which to represent the data and controls smoothness with a roughness penalty operator. Penalizing the PLS weights imposes smoothness on the resulting coefficient function, improving its interpretability. In a simulation study, we demonstrate the advantages of pFFPLS compared to non-penalized FFPLS. Our comparisons indicate a higher accuracy of pFFPLS when predicting the response and estimating the true coefficient function from which the data were generated. We also illustrate the advantages of our proposal with two case studies involving two well-known datasets from the functional data analysis literature. In the first one, we predict log precipitation curves from the yearly temperature profiles recorded in 35 weather stations in Canada. In the second case study, we predict the hip angle profiles during a gait cycle of children from their corresponding knee angle profiles

    Slanted Stixels: A way to represent steep streets

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    This work presents and evaluates a novel compact scene representation based on Stixels that infers geometric and semantic information. Our approach overcomes the previous rather restrictive geometric assumptions for Stixels by introducing a novel depth model to account for non-flat roads and slanted objects. Both semantic and depth cues are used jointly to infer the scene representation in a sound global energy minimization formulation. Furthermore, a novel approximation scheme is introduced in order to significantly reduce the computational complexity of the Stixel algorithm, and then achieve real-time computation capabilities. The idea is to first perform an over-segmentation of the image, discarding the unlikely Stixel cuts, and apply the algorithm only on the remaining Stixel cuts. This work presents a novel over-segmentation strategy based on a Fully Convolutional Network (FCN), which outperforms an approach based on using local extrema of the disparity map. We evaluate the proposed methods in terms of semantic and geometric accuracy as well as run-time on four publicly available benchmark datasets. Our approach maintains accuracy on flat road scene datasets while improving substantially on a novel non-flat road dataset.Comment: Journal preprint (published in IJCV 2019: https://link.springer.com/article/10.1007/s11263-019-01226-9). arXiv admin note: text overlap with arXiv:1707.0539

    Comparison of ileofemoral arterial access size between noncontrast 3T MR angiography and contrast‐enhanced computed tomographic angiography in patients referred for transcatheter aortic valve replacement

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140012/1/jmri25651.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/140012/2/jmri25651_am.pd

    Symphony on strong field approximation

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    This paper has been prepared by the Symphony collaboration (University of Warsaw, Uniwersytet Jagiellonski, DESY/CNR and ICFO) on the occasion of the 25th anniversary of the 'simple man's models' which underlie most of the phenomena that occur when intense ultrashort laser pulses interact with matter. The phenomena in question include high-harmonic generation (HHG), above-threshold ionization (ATI), and non-sequential multielectron ionization (NSMI). 'Simple man's models' provide both an intuitive basis for understanding the numerical solutions of the time-dependent Schrodinger equation and the motivation for the powerful analytic approximations generally known as the strong field approximation (SFA). In this paper we first review the SFA in the form developed by us in the last 25 years. In this approach the SFA is a method to solve the TDSE, in which the non-perturbative interactions are described by including continuum-continuum interactions in a systematic perturbation-like theory. In this review we focus on recent applications of the SFA to HHG, ATI and NSMI from multi-electron atoms and from multi-atom molecules. The main novel part of the presented theory concerns generalizations of the SFA to: (i) time-dependent treatment of two-electron atoms, allowing for studies of an interplay between electron impact ionization and resonant excitation with subsequent ionization; (ii) time-dependent treatment in the single active electron approximation of 'large' molecules and targets which are themselves undergoing dynamics during the HHG or ATI processes. In particular, we formulate the general expressions for the case of arbitrary molecules, combining input from quantum chemistry and quantum dynamics. We formulate also theory of time-dependent separable molecular potentials to model analytically the dynamics of realistic electronic wave packets for molecules in strong laser fields. We dedicate this work to the memory of Bertrand Carre, who passed away in March 2018 at the age of 60

    Direct exfoliation and dispersion of two-dimensional materials in pure water via temperature control

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    The high-volume synthesis of two-dimensional (2D) materials in the form of platelets is desirable for various applications. While water is considered an ideal dispersion medium, due to its abundance and low cost, the hydrophobicity of platelet surfaces has prohibited its widespread use. Here we exfoliate 2D materials directly in pure water without using any chemicals or surfactants. In order to exfoliate and disperse the materials in water, we elevate the temperature of the sonication bath, and introduce energy via the dissipation of sonic waves. Storage stability greater than one month is achieved through the maintenance of high temperatures, and through atomic and molecular level simulations, we further discover that good solubility in water is maintained due to the presence of platelet surface charges as a result of edge functionalization or intrinsic polarity. Finally, we demonstrate inkjet printing on hard and flexible substrates as a potential application of water-dispersed 2D materials.close1

    Influencia de grelina y leptina sobre alteraciones psiquiátricas en sujetos con obesidad

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    La obesidad (índice de masa corporal [IMC] > 30 kg/m2) se define como el exceso en la proporción del tejido adiposo; consecuencia de un ingreso calórico superior al gasto energético del individuo. Es considerada un problema inflamatorio, sistémico, crónico y recurrente que causa diversas complicaciones. Esta enfermedad se ha relacionado con diversos problemas metabólicos y fisiológicos ampliamente estudiados; además de psicopatológicos.La obesidad es un problema de salud pública en diversos países, principalmente en Norteamérica. Se ha observado que sujetos que presentan obesidad manifiestan numerosas alteraciones psiquiátricas, entre ellas: depresión, ansiedad y trastorno por atracón. Por ello, diversos estudios han llegado a la conclusión de que las hormonas gastrointestinales fungen un papel crucial en el establecimiento de conductas, siendo la orexigénica grelina y la anorexigénica leptina 2 de las hormonas con mayor participación activa. Dicha intervención se debe a que ambas hormonas presentan receptores en sistema nervioso central, primordialmente en áreas del sistema límbico, regulador crucial de conductas hedónicas. Por lo tanto, en la presente revisión bibliográfica describiremos el papel de la grelina y la leptina sobre la expresión de conductas psicopatológicas comunes en sujetos que padecen obesidad
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