1,552 research outputs found

    Asymptotic Normality of the Maximum Pseudolikelihood Estimator for Fully Visible Boltzmann Machines

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    Boltzmann machines (BMs) are a class of binary neural networks for which there have been numerous proposed methods of estimation. Recently, it has been shown that in the fully visible case of the BM, the method of maximum pseudolikelihood estimation (MPLE) results in parameter estimates which are consistent in the probabilistic sense. In this article, we investigate the properties of MPLE for the fully visible BMs further, and prove that MPLE also yields an asymptotically normal parameter estimator. These results can be used to construct confidence intervals and to test statistical hypotheses. We support our theoretical results by showing that the estimator behaves as expected in a simulation study

    Mixtures of Spatial Spline Regressions

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    We present an extension of the functional data analysis framework for univariate functions to the analysis of surfaces: functions of two variables. The spatial spline regression (SSR) approach developed can be used to model surfaces that are sampled over a rectangular domain. Furthermore, combining SSR with linear mixed effects models (LMM) allows for the analysis of populations of surfaces, and combining the joint SSR-LMM method with finite mixture models allows for the analysis of populations of surfaces with sub-family structures. Through the mixtures of spatial splines regressions (MSSR) approach developed, we present methodologies for clustering surfaces into sub-families, and for performing surface-based discriminant analysis. The effectiveness of our methodologies, as well as the modeling capabilities of the SSR model are assessed through an application to handwritten character recognition

    Simple Combined Model for Nonlinear Excitations in DNA

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    We propose a new simple model for DNA denaturation bases on the pendulum model of Englander\cite{A1} and the microscopic model of Peyrard {\it et al.},\cite{A3} so called "combined model". The main parameters of our model are: the coupling constant kk along each strand, the mean stretching y∗y^\ast of the hydrogen bonds, the ratio of the damping constant and driven force γ/F\gamma/F. We show that both the length LL of unpaired bases and the velocity vv of kinks depend on not only the coupling constant kk but also the temperature TT. Our results are in good agreement with previous works.Comment: 6 pages, 10 figures, submitted to Phys. Rev.

    Thermal kinetic inductance detectors for ground-based millimeter-wave cosmology

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    We show measurements of thermal kinetic inductance detectors (TKID) intended for millimeter wave cosmology in the 200-300 GHz atmospheric window. The TKID is a type of bolometer which uses the kinetic inductance of a superconducting resonator to measure the temperature of the thermally isolated bolometer island. We measure bolometer thermal conductance, time constant and noise equivalent power. We also measure the quality factor of our resonators as the bath temperature varies to show they are limited by effects consistent with coupling to two level systems.Comment: 8 pages, 4 figures. Submitted to Journal of Low Temperature Physic

    Influence du changement climatique sur la diversité inter et intra-spécifique des plantes cultivées à Tougou au nord du Burkina Faso

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    L’objectif de l’étude est d’évaluer la diversité taxonomique et la variabilité inter et intra-spécifique des plantes cultivées non spontanées dans un contexte de changement climatique. Les données sont collectées à l’aide d’une enquête au près de 75 producteurs menée suivant des interviews semi-structurées. Les résultats ont révélé l’existence de 122 écotypes appartenant à 49 espèces, 39 genres et 22 familles. La diversité interspécifique représentait 73% de la diversité des plantes cultivées au plan national. La variabilité intraspécifique était faible comparée à la variabilité au plan national. Elle était plus élevée chez les céréales et les cultures potagères pluviales avec 2 à 10 écotypes par espèce contre 1 à 3 écotypes par espèce chez les cultures maraîchères. Les écotypes ayant un cycle de plus de 90 jours représentant 10,5% de l’ensemble des écotypes recensés, sont menacés de disparition à cause du changement climatique. Une stratégie de collecte, de conservation, d’amélioration et de promotion de ces ressources ainsi que la restauration des écosystèmes dégradés s’avèrent nécessaire pour le maintien de la phytodiversité cultivée.Mots clés: Burkina Faso, agro biodiversité, écotype, espèces menacées, conservatio

    Valorisation de substrats organiques divers dans l'agriculture péri-urbaine de Ouagadougou (Burkina Faso) pour l'amendement et la fertilisation des sols : acteurs et pratiques

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    Organic substrates recycling in the sub-urban agriculture of Ouagadougou (Burkina Faso) for soils fertilization: description of the different actors and their practices. This study aimed to establish an overview of the main actors of the sub-urban agriculture of Ouagadougou, their practices and expectations, and to characterize the used organic substrates (OS). For that, a farm survey was carried out on the most representative sites with 64 persons (cereal farmers, truckers and nurserymen) randomly chosen. OS were sampled with each actor, when available. Thus, 27 samples were taken and characterized through chemical analyses and laboratory incubations to follow organic carbon mineralization. The results highlighted that 35% of cereal farmers, 69% of truckers and 95% of nurserymen were 20 to 40 years old, that a large proportion of cereal farmers and truckers were not sent to school while 70% of nurserymen had at least primary education. Sub-urban agriculture was the only activity for 43% of farmers, 83% of truckers and 91% of nurserymen. Moreover, 71% of cereal farmers and 73% of nurserymen used municipal wastes as source of organic matter against only 17% of truckers, the majority of them using animal manures. The main criterion of choice of OS was their availability without any other consideration. Even if a large majority of the actors think that composts of OS were better than brut OS, a minority of them used currently composts. The best ways for an adoption and utilization of OS composts were to facilitate their accessibility and to promote these composts, composting techniques and their interests through advertising in mass media. Chemical analyses and laboratory incubations showed a great variability of the SUW, both in the same group and actors' groups. However, in case of total organic carbon, total nitrogen and total phosphorous contents, the following tendencies were observed: Contenttruckers > Contentfarmers > Contentnurserymen. For the sum of major elements Ca, K, Mg, Na (SME), it was observed that SMEtruckers ≈ SMEfarmers > SMEnurserymen. In addition, except a few atypical substrates, OS used by nurserymen were largely stabilized compared to those of cereal farmers and truckers

    The Design and Operation of The Keck Observatory Archive

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    The Infrared Processing and Analysis Center (IPAC) and the W. M. Keck Observatory (WMKO) operate an archive for the Keck Observatory. At the end of 2013, KOA completed the ingestion of data from all eight active observatory instruments. KOA will continue to ingest all newly obtained observations, at an anticipated volume of 4 TB per year. The data are transmitted electronically from WMKO to IPAC for storage and curation. Access to data is governed by a data use policy, and approximately two-thirds of the data in the archive are public.Comment: 12 pages, 4 figs, 4 tables. Presented at Software and Cyberinfrastructure for Astronomy III, SPIE Astronomical Telescopes + Instrumentation 2014. June 2014, Montreal, Canad

    Design an Intelligent System to automatically Tutor the Method for Solving Problems

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    Nowadays, intelligent systems have been applied in many real-word domains. The Intelligent chatbot is an intelligent system, it can interact with the human to tutor how to work some activities. In this work, we design an architecture to build an intelligent chatbot, which can tutor to solve problems, and construct scripts for automatically tutoring. The knowledge base of the intelligent tutoring chatbot is designed by using the requirements of an Intelligent Problem Solver. It is the combination between the knowledge model of relations and operators, and the structures of hint questions and sample problems, which are practical cases. Based on the knowledge base and tutoring scripts, a tutoring engine is designed. The tutoring chatbot plays as an instructor for solving real-world problems. It simulates the working of the instructor to tutor the user for solving problems. By utilizing the knowledge base and reasoning, the architecture of the intelligent chatbot are emerging to apply in the real-world. It is used to build an intelligent chatbot to support the learning of high-school mathematics and a consultant system in public administration. The experimental results show the effectiveness of the proposed method in comparison with the existing systems
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