6,964 research outputs found

    Multivariate time series classification with temporal abstractions

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    The increase in the number of complex temporal datasets collected today has prompted the development of methods that extend classical machine learning and data mining methods to time-series data. This work focuses on methods for multivariate time-series classification. Time series classification is a challenging problem mostly because the number of temporal features that describe the data and are potentially useful for classification is enormous. We study and develop a temporal abstraction framework for generating multivariate time series features suitable for classification tasks. We propose the STF-Mine algorithm that automatically mines discriminative temporal abstraction patterns from the time series data and uses them to learn a classification model. Our experimental evaluations, carried out on both synthetic and real world medical data, demonstrate the benefit of our approach in learning accurate classifiers for time-series datasets. Copyright © 2009, Assocation for the Advancement of ArtdicaI Intelligence (www.aaai.org). All rights reserved

    The Quantum Cocktail Party

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    We consider the problem of decorrelating states of coupled quantum systems. The decorrelation can be seen as separation of quantum signals, in analogy to the classical problem of signal-separation rising in the so-called cocktail-party context. The separation of signals cannot be achieved perfectly, and we analyse the optimal decorrelation map in terms of added noise in the local separated states. Analytical results can be obtained both in the case of two-level quantum systems and for Gaussian states of harmonic oscillators.Comment: 4 pages, 2figures, revtex

    Quantum state decorrelation

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    We address the general problem of removing correlations from quantum states while preserving local quantum information as much as possible. We provide a complete solution in the case of two qubits, by evaluating the minimum amount of noise that is necessary to decorrelate covariant sets of bipartite states. We show that two harmonic oscillators in arbitrary Gaussian state can be decorrelated by a Gaussian covariant map. Finally, for finite-dimensional Hilbert spaces, we prove that states obtained from most cloning channels (e.g., universal and phase-covariant cloning) can be decorrelated only at the expense of a complete erasure of information about the copied state. More generally, in finite dimension, cloning without correlations is impossible for continuous sets of states. On the contrary, for continuos variables cloning, a slight modification of the customary set-up for cloning coherent states allows one to obtain clones without correlations.Comment: 11 pages, 2 figures, RevTex

    Generating qudits with d=3,4 encoded on two-photon states

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    We present an experimental method to engineer arbitrary pure states of qudits with d=3,4 using linear optics and a single nonlinear crystal.Comment: 4 pages, 1 eps figure. Minor changes. The title has been changed for publication on Physical Review

    VERTICAL JUMP CHARACTERISTICS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

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    The purpose of this study was to compare two-legged countermovement vertical jump characteristics between operated and non-operated lower limbs of twelve recreational athletes who had undergone unilateral ACL surgical reconstruction. A control group of eight uninjured athletes was employed. Bilateral vertical ground reaction forces, joint angles, moments and powers patterns were measured and statistically analysed. The examination of the angular kinematics revealed for the injured limb a significant reduction of the knee and ankle extension angles at the take off and an ankle ROM reduction. Examining peak moments and powers the injured knee exhibited significant lower values. The reduction of the knee peak power seems to be compensated in most of the subjects by an increase of the omolateral ankle peak power

    X-ray method to study temperature-dependent stripe domains in MnAs/GaAs(001)

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    MnAs films grown on GaAs (001) exhibit a progressive transition between hexagonal (ferromagnetic) and orthorhombic (paramagnetic) phases at wide temperature range instead of abrupt transition during the first-order phase transition. The coexistence of two phases is favored by the anisotropic strain arising from the constraint on the MnAs films imposed by the substrate. This phase coexistence occurs in ordered arrangement alternating periodic terrace steps. We present here a method to study the surface morphology throughout this transition by means of specular and diffuse scattering of soft x-rays, tuning the photon energy at the Mn 2p resonance. The results show the long-range arrangement of the periodic stripe-like structure during the phase coexistence and its period remains constant, in agreement with previous results using other techniques.Comment: 4 pages, 4 figures, submitted to Applied Physics Letter

    Flavor chemistry of virgin olive oil: An overview

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    Virgin olive oil (VOO) has unique chemical characteristics among all other vegetable oils which are of paramount importance for human health. VOO constituents are also responsible of its peculiar flavor, a complex sensation due to a combination of aroma, taste, texture, and mouthfeel or trigeminal sensations. VOO flavor depends primarily on the concentration and nature of volatile and phenolic compounds present in olive oil which can change dramatically depending on agronomical and technological factors. Another aspect that can change the flavor perception is linked to the oral process during olive oil tasting. In fact, in this case, some human physiological and matrix effects modulate the flavor release in the mouth. The present review aims to give an overview on VOO flavor, with particular emphasis on the mechanisms affecting its production and release during a tasting

    The Noble Method in the dairy sector as a sustainable production system to improve the nutritional composition of dairy products: A review

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    Sustainable production systems in line with consumer expectations are attractive for the dairy sector. The objective of this review is to examine the benefits of an Italian method, named the Noble Method (‘Metodo Nobile ’), in order to improve the nutritional properties of milk and environmental sustainability. The prohibition of silage and the use of polyphite pastures are some of the rules established by the Noble Method. The greater amount of unsaturated fatty acids and other beneficial compounds found in milk and dairy products produced by using milk from animals fed on well-managed pasture could have positive implications on consumers’ health

    3-D KINEMATIC ANALYSIS OF CANOEING ON A SIMULATOR: DIFFERENCES BETWEEN ELITE, INTERMEDIATE AND NOVICE CANOISTS

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    Using 3-D kinematic analysis, this paper identified kinematic variables that govern successful performance in canoeing on a simulator. The presence of side-to-side asymmetries in selected linear and angular variables was investigated. Elite, intermediate and novice canoeists participated. Similar to previously results for symmetrical cyclic sport activities like cross-country skiing, running and cycling, elite athletes evidenced higher movement amplitude and a more symmetric behavior compared with intermediate and novice paddlers. The less experienced athletes evidenced more accentuated saddle and pelvis movements in the frontal plane. Aerobic and anaerobic capacities and technical skills developed over years of training may explain the reported difference

    Magnetic reconfiguration of MnAs/GaAs(001) observed by Magnetic Force Microscopy and Resonant Soft X-ray Scattering

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    We investigated the thermal evolution of the magnetic properties of MnAs epitaxial films grown on GaAs(001) during the coexistence of hexagonal/orthorhombic phases using polarized resonant (magnetic) soft X-ray scattering and magnetic force microscopy. The results of the diffuse satellite X-ray peaks were compared to those obtained by magnetic force microscopy and suggest a reorientation of ferromagnetic terraces as temperature rises. By measuring hysteresis loops at these peaks we show that this reorientation is common to all ferromagnetic terraces. The reorientation is explained by a simple model based on the shape anisotropy energy. Demagnetizing factors were calculated for different configurations suggested by the magnetic images. We noted that the magnetic moments flip from an in-plane mono-domain orientation at lower temperatures to a three-domain out-of-plane configuration at higher temperatures. The transition was observed when the ferromagnetic stripe width L is equal to 2.9 times the film thickness d. This is in good agreement with the expected theoretical value of L = 2.6d.Comment: 16 pages in PD
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