69,171 research outputs found

    Directed abelian algebras and their applications to stochastic models

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    To each directed acyclic graph (this includes some D-dimensional lattices) one can associate some abelian algebras that we call directed abelian algebras (DAA). On each site of the graph one attaches a generator of the algebra. These algebras depend on several parameters and are semisimple. Using any DAA one can define a family of Hamiltonians which give the continuous time evolution of a stochastic process. The calculation of the spectra and ground state wavefunctions (stationary states probability distributions) is an easy algebraic exercise. If one considers D-dimensional lattices and choose Hamiltonians linear in the generators, in the finite-size scaling the Hamiltonian spectrum is gapless with a critical dynamic exponent z=Dz = D. One possible application of the DAA is to sandpile models. In the paper we present this application considering one and two dimensional lattices. In the one dimensional case, when the DAA conserves the number of particles, the avalanches belong to the random walker universality class (critical exponent στ=3/2\sigma_{\tau} = 3/2). We study the local densityof particles inside large avalanches showing a depletion of particles at the source of the avalanche and an enrichment at its end. In two dimensions we did extensive Monte-Carlo simulations and found στ=1.782±0.005\sigma_{\tau} = 1.782 \pm 0.005.Comment: 14 pages, 9 figure

    Nonparametric Bayesian Double Articulation Analyzer for Direct Language Acquisition from Continuous Speech Signals

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    Human infants can discover words directly from unsegmented speech signals without any explicitly labeled data. In this paper, we develop a novel machine learning method called nonparametric Bayesian double articulation analyzer (NPB-DAA) that can directly acquire language and acoustic models from observed continuous speech signals. For this purpose, we propose an integrative generative model that combines a language model and an acoustic model into a single generative model called the "hierarchical Dirichlet process hidden language model" (HDP-HLM). The HDP-HLM is obtained by extending the hierarchical Dirichlet process hidden semi-Markov model (HDP-HSMM) proposed by Johnson et al. An inference procedure for the HDP-HLM is derived using the blocked Gibbs sampler originally proposed for the HDP-HSMM. This procedure enables the simultaneous and direct inference of language and acoustic models from continuous speech signals. Based on the HDP-HLM and its inference procedure, we developed a novel double articulation analyzer. By assuming HDP-HLM as a generative model of observed time series data, and by inferring latent variables of the model, the method can analyze latent double articulation structure, i.e., hierarchically organized latent words and phonemes, of the data in an unsupervised manner. The novel unsupervised double articulation analyzer is called NPB-DAA. The NPB-DAA can automatically estimate double articulation structure embedded in speech signals. We also carried out two evaluation experiments using synthetic data and actual human continuous speech signals representing Japanese vowel sequences. In the word acquisition and phoneme categorization tasks, the NPB-DAA outperformed a conventional double articulation analyzer (DAA) and baseline automatic speech recognition system whose acoustic model was trained in a supervised manner.Comment: 15 pages, 7 figures, Draft submitted to IEEE Transactions on Autonomous Mental Development (TAMD

    Analisa korespodensi berganda pada daa berkategori multivariabel

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    Analisa Korespondensi Berganda pada data Q-variat (Q-2) merupakan suatu pendekatan dalam menganalisa suatu data multivariat. Secara teknis rnetode ini mengolah suatu data berkategori yang diperoleh dari data hasil survey, untuk disajikan dalam bentuk matrik data berkode biner. Matrik data ini kemudian dimampatkan dalam bentuk tabel kontingensi Burt. Kemudian untuk menganalisa hubungan antara variabel-variabelnya, dicari akar-akar karakteristiknya dan vektor karakteristik yang berpadanan dengan suatu nilai karakteristik terbesar. Bentuk hubungan antar variabel ditunjukkan dalam suatu persamaan faktor, yang menggarnbarkan profil vektor bans dan profil vektor kolom dari tabel kontingensi. yang kemudian secara geometris divisualisasikan dalam bidang dimensi dua, dan disini dapat diberikan nilai-nilai koordinat dalam bidang R2. Dicontohkan koordinat pada sumbu ? dan X2 dari persamaan faktor untuk Q=2 variabel. Multiple Correspondence Analysis of Q-variat data (Q?_2) is the approximation in data analysis of multivariate data. This methode process the categorical data from survey result data to be presented to binary coding of matrix data. The matrix is condensed to butt's contingency table. Analizing the correspondence among variables to be founded eigenvalues and eigenvectors of relative to the largest eigenvalues. The correspondence form among the variables is showed in the factors equation that describe rows and columns vectorprofiles from contingency table, so that to be described in two dimension space and that is gived coordinate values in R2 space. For example, the coordinates in X and A,2 axes from factors equation of Q = 2 variable

    Detect-and-Avoid: Flight Test 6 Scripted Encounters Data Analysis

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    The Unmanned Aircraft System (UAS) in the National Airspace System (NAS) project conducted Flight Test 6 (FT6) in 2019. The ultimate goal of this flight test was to produce data to inform RTCA SC-228's Phase II Minimum Operational Performance Standards (MOPS) for Detect and Avoid (DAA) and Low Size, Weight, and Power Sensors. This report documents the analysis of scripted encounters' data. Scripted encounters own were analyzed and categorized based on the outcome of alert, maneuver guidance, and effectiveness of pilots' maneuver in resolving conflicts. Results indicate that UAS pilots' decisions as well as intruder maneuvers are leading factors that contribute to ineffective DAA maneuvers. Results also show that adding buffers to the DAA's suggested minimum turn angle improves effectiveness of the DAA maneuvers

    The Ideal Candidate. Analysis of Professional Competences through Text Mining of Job Offers

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    The aim of this paper is to propose analytical tools for identifying peculiar aspects of job market for graduates. We propose a strategy for dealing with daa tat have different source and nature

    Access and response to direct antiviral agents (DAA) in HIV-HCV co-infected patients in Italy: Data from the Icona cohort

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    Background Real-life data on access and response to direct antiviral agents (DAA) in HIV-HCV coinfected individuals are lacking. Methods HCV viremic, HIV-positive patients from Icona and Hepaicona cohorts nave to DAA by January 2013 were included. Access and predictors of starting DAA were evaluated. Switches of antiretroviral drugs at starting DAA were described. We calculated sustained virological response (SVR12) in those reaching 12 weeks after end-of-treatment (EOT), and defined treatment failure (TF) as discontinuation of DAA before EOT or non-SVR12. Statistical analyses included Kaplan-Meier curves, univariable and multivariable analyses evaluating predictors of access to DAA and of treatment outcome (non-SVR and TF). Results 2,607 patients included. During a median follow-up of 38 (IQR:30-41) months, 920 (35.3%) patients started DAA. Eligibility for reimbursement was the strongest predictor to access to treatment: 761/1,090 (69.8%) eligible and 159/1,517 (10.5%) non-eligible to DAA reimbursement. Older age, HIV-RNA50 copies/mL were associated to faster DAA initiation, higher CD4 count and HCV-genotype 3 with delayed DAA initiation in those eligible to DAA reimbursement. Up to 28% of patients (36% of those on ritonavir-boosted protease inhibitors, PI/r) underwent antiretroviral (ART) modification at DAA initiation. 545/595 (91.6%) patients reaching EOT achieved SVR12. Overall, TF occurred in 61/606 patients (10.1%), with 11 discontinuing DAA before EOT. Suboptimal DAA was the only independent predictor of both non-SVR12 (AHR 2.52, 95%CI:1.24-5.12) and TF (AHR: 2.19; 95%CI:1.13-4.22). Conclusions Only 35.3% had access to HCV treatment. Despite excellent rates of SVR12 rates (91.6%), only 21% (545/2,607) of our HIV-HCV co-infected patients are cured. © 2017 d'Arminio Monforte et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Vasoconstrictor and Pressor Effects of Des-Aspartate-Angiotensin I in Rat

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    This study investigated the vasoactive effects of des-aspartate-angiotensin-I (DAA-I) in male Wistar rats on whole body vascular bed, isolated perfused kidneys, and aortic rings. Dose–response curves to DAA-I were compared with those to angiotensin II (Ang II). The Ang II-type-1 (AT1) receptor blocker, losartan, was used to evaluate the role of AT1 receptors in the responses to DAA-I. Studies were also conducted of the responsiveness in aortic rings after endothelium removal, nitric oxide synthase inhibition, or AT2 receptor blockade. DAA-I induced a dose-related systemic pressor response that was shifted to the right compared with Ang II. Losartan markedly attenuated the responsiveness to DAA-I. DAA-I showed a similar pattern in renal vasculature and aortic rings. In aortic rings, removal of endothelium and nitric oxide inhibition increased the sensitivity and maximal response to DAA-I and Ang II. AT2 receptor blockade did not significantly affect the responsiveness to DAA-I. According to these findings, DAA-I increases the systemic blood pressure and vascular tone in conductance and resistance vessels via AT1 receptor activation. This vasoconstrictor effect of DAA-I participates in the homeostatic control of arterial pressure, which can also contribute to the pathogenesis of hypertension. DAA-I may therefore be a potential therapeutic target in cardiovascular disease
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