6,873 research outputs found
Probabilistic Inference from Arbitrary Uncertainty using Mixtures of Factorized Generalized Gaussians
This paper presents a general and efficient framework for probabilistic
inference and learning from arbitrary uncertain information. It exploits the
calculation properties of finite mixture models, conjugate families and
factorization. Both the joint probability density of the variables and the
likelihood function of the (objective or subjective) observation are
approximated by a special mixture model, in such a way that any desired
conditional distribution can be directly obtained without numerical
integration. We have developed an extended version of the expectation
maximization (EM) algorithm to estimate the parameters of mixture models from
uncertain training examples (indirect observations). As a consequence, any
piece of exact or uncertain information about both input and output values is
consistently handled in the inference and learning stages. This ability,
extremely useful in certain situations, is not found in most alternative
methods. The proposed framework is formally justified from standard
probabilistic principles and illustrative examples are provided in the fields
of nonparametric pattern classification, nonlinear regression and pattern
completion. Finally, experiments on a real application and comparative results
over standard databases provide empirical evidence of the utility of the method
in a wide range of applications
Heatmaps in soccer: event vs tracking datasets
We investigate how similar heatmaps of soccer players are when constructed
from (i) event datasets and (ii) tracking datasets. When using event datasets,
we show that the scale at which the events are grouped strongly influences the
correlation with the tracking heatmaps. Furthermore, there is an optimal scale
at which the correlation between event and tracking heatmaps is the highest.
However, even at the optimal scale, correlations between both approaches are
moderate. Furthermore, there is high heterogeneity in the players' correlation,
ranging from negative values to correlations close to the unity. We show that
the number of events performed by a player does not crucially determine the
level of correlation between both heatmaps. Finally, we analyzed the influence
of the player position, showing that defenders are the players with the highest
correlations while forwards have the lowest.Comment: 6 pages, 5 figure
A Study of Two-Temperature Non-Equilibrium Ising Models: Critical Behavior and Universality
We study a class of 2D non-equilibrium Ising models based on competing
dynamics induced by contact with heat-baths at two different temperatures. We
make a comparative study of the non-equilibrium versions of Metropolis, heat
bath/Glauber and Swendsen-Wang dynamics and focus on their critical behavior in
order to understand their universality classes. We present strong evidence that
some of these dynamics have the same critical exponents and belong to the same
universality class as the equilibrium 2D Ising model. We show that the bond
version of the Swendsen-Wang update algorithm can be mapped into an equilibrium
model at an effective temperature.Comment: 12 pages of LaTeX plus 18 pages of postscript figures in a uuencoded
file (608k
Stability and Reversible Oxidation of Sub-Nanometric Cu5 Metal Clusters: Integrated Experimental Study and Theoretical Modeling**
Sub-nanometer metal clusters have special physical and chemical properties, significantly different from those of nanoparticles. However, there is a major concern about their thermal stability and susceptibility to oxidation. In situ X-ray Absorption spectroscopy and Near Ambient Pressure X-ray Photoelectron spectroscopy results reveal that supported Cu5 clusters are resistant to irreversible oxidation at least up to 773 K, even in the presence of 0.15 mbar of oxygen. These experimental findings can be formally described by a theoretical model which combines dispersion-corrected DFT and first principles thermochemistry revealing that most of the adsorbed O2 molecules are transformed into superoxo and peroxo species by an interplay of collective charge transfer within the network of Cu atoms and large amplitude âbreathingâ motions. A chemical phase diagram for Cu oxidation states of the Cu5-oxygen system is presented, clearly different from the already known bulk and nano-structured chemistry of Cu
Electrochemical and bioelectrocatalytical properties of novel block-copolymers containing interacting ferrocenyl units
The electrochemical characterization of three different polystyrene-b-polybutadiene block copolymers functionalized with ferrocenyl units electronically communicated, PSm-PBn(HSiMeFc2)p where m=615, n=53, p=39 (1), m=375, n=92, p=76 (2) and m=455, n=204, p=170 (3), has been carried out both in solution and electrochemically deposited onto platinum electrodes. The bioelectrocatalytical properties of electrodes modified with the polymers in the nicotinamide dinucleotide (NADH) and glucose oxidase (GOx) oxidations have been investigated as a function of the constitution and structure of the polymers. The analytical properties of electrodes modified with these polymers as sensors of NADH and GOx are described. In addition, an amperometric biosensor for glucose, prepared by electrostatic immobilization of glucose oxidase onto a platinum electrode modified with one of the ferrocenyl block copolymers as an example, has been developed. The results confirm that electrodes modified with the examined copolymers act as efficient redox mediators for the electrocatalytic oxidation of both reduced nicotinamide dinucleotide cofactor and glucose oxidase. The reaction with NADH proceeds via formation of a charge-transfer intermediate before yielding the reaction products. This is a novel example of electrodes modified with ferrocene derivatives that can be applied to the determination of NADH without the use of diaphorase. The redox copolymers co-immobilized with glucose-oxidase have been successfully used as amperometric biosensors for glucose determinations. As expected these compounds allow using lower working potentials. The sensitivities and detection limits obtained are comparable or even better than those of other ferrocene-modified polymers mediator electrodes
Silicon quantum dots in photovoltaic devices: device fabrication, characterization and comparison of materials
The realization of crystalline silicon tandem solar cells relies on silicon nanocrystal (Si NC) quantum dots as
the absorber of the top solar cell. Quantum confinement of charge carriers within the nanocrystals permits to
achieve a band gap up to 2 eV which can be adjusted according to the size of the nanocrystals. This enables the
construction of all-crystalline Si tandem solar cells, and increases the theoretical efficiency limit from 33 % to
42.5 % due to the addition of a second band gap. In this work, the electrical and photovoltaic properties of Si
NC films are assessed and the most prominent material systems (SiO2, Si3N4, SiC) are compared. P-i-n solar
cells are presented which feature Si NC as the intrinsic absorber layer and permit to characterize quantum
confinement electrically on device level. P-i-n solar cells with Si NC in SiC in the i-region have yielded open
circuit voltages of up to 370mV
PACIFIC-R: First real-world study of patients with unresectable, stage III NSCLC treated with durvalumab after chemoradiotherapy
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Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.This work was supported by the Ministero dellâIstruzione, dellâUniversitĂ e della Ricerca (Italy) and the MINECO (Spain) (Projects PID2019â104778GBâI00, CTQ 2017â86735âP, RTCâ2017â6331â5, Severo Ochoa program SEVâ2016â0683 and Excellence Unit âMaria de Maeztuâ CEX2019â000919âM). E.T. and M.M. thank MINECO and ITQ for the concession of a contract. D.A. acknowledges the financial support of the Fondazione CARIPLO/âEconomia Circolare: ricerca per un futuro sostenibileâ 2019, Project code: 2019â2090, MOCA and Diamond Light Source for awarded beamtime and provision of synchrotron radiation facilities and thanks Dr. Sarah Barnett and David Allan for their assistance at I19 beamline (Proposal No. MT18768-1). Thanks are also extended to the â2019 Post-doctoral Junior Leader-Retaining Fellowship, la Caixa Foundation (ID100010434 and fellowship code LCF/BQ/PR19/11700011â (J.F.-S.) and âLa Caixaâ scholarship (ID 100010434) LCF/BQ/DI19/11730029 (J.B.-S). E.P. acknowledges the financial support of the European Research Council under the European Unionâs Horizon 2020 research and innovation programme/ERC Grant Agreement No 814804, MOF reactors. J.O.-M. acknowledges the Juan de la Cierva program for the concession of a contract (IJC2018-036514-I). We gratefully acknowledge to ALBA synchrotron for allocating beamtime and CLĂSS beamline staff for their technical support during our experiment. The computations were performed on the Tirant III cluster of the Servei dâInformĂ tica of the University of Valencia.Peer reviewe
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