1,731 research outputs found

    Alleviating Naive Bayes attribute independence assumption by attribute weighting

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    Despite the simplicity of the Naive Bayes classifier, it has continued to perform well against more sophisticated newcomers and has remained, therefore, of great interest to the machine learning community. Of numerous approaches to refining the naive Bayes classifier, attribute weighting has received less attention than it warrants. Most approaches, perhaps influenced by attribute weighting in other machine learning algorithms, use weighting to place more emphasis on highly predictive attributes than those that are less predictive. In this paper, we argue that for naive Bayes attribute weighting should instead be used to alleviate the conditional independence assumption. Based on this premise, we propose a weighted naive Bayes algorithm, called WANBIA, that selects weights to minimize either the negative conditional log likelihood or the mean squared error objective functions. We perform extensive evaluations and find that WANBIA is a competitive alternative to state of the art classifiers like Random Forest, Logistic Regression and A1DE. © 2013 Nayyar A. Zaidi, Jesus Cerquides, Mark J. Carman and Geoffrey I. Webb.This research has been supported by the Australian Research Council under grant DP110101427 and Asian Office of Aerospace Research and Development, Air Force Office of Scientific Research under contract FA23861214030. The authors would like to thank Mark Hall for providing the code for CFS and MH. The authors would also like to thank anonymous reviewers for their insightful comments that helped improving the paper tremendously.Peer Reviewe

    Self-trapping of excitons, violation of condon approximation, and efficient fluorescence in conjugated cycloparaphenylenes

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    Cycloparaphenylenes, the simplest structural unit of armchair carbon nanotubes, have unique optoelectronic properties counterintuitive in the class of conjugated organic materials. Our time-dependent density functional theory study and excited state dynamics simulations of cycloparaphenylene chromophores provide a simple and conceptually appealing physical picture explaining experimentally observed trends in optical properties in this family of molecules. Fully delocalized degenerate second and third excitonic states define linear absorption spectra. Self-trapping of the lowest excitonic state due to electron-phonon coupling leads to the formation of spatially localized excitation in large cycloparaphenylenes within 100 fs. This invalidates the commonly used Condon approximation and breaks optical selection rules, making these materials superior fluorophores. This process does not occur in the small molecules, which remain inefficient emitters. A complex interplay of symmetry, π-conjugation, conformational distortion and bending strain controls all photophysics of cycloparaphenylenes.Fil: Adamska, Lyudmyla. Los Alamos National Laboratory. Los Alamos; Estados UnidosFil: Nayyar, Iffat. Los Alamos National Laboratory. Los Alamos; Estados UnidosFil: Chen, Hang. Boston University; Estados UnidosFil: Swan, Anna K.. Boston University; Estados UnidosFil: Oldani, Andres Nicolas. Universidad Nacional de Quilmes; ArgentinaFil: Fernández Alberti, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Golder, Matthew R.. University of Oregon; Estados UnidosFil: Jasti, Ramesh. University of Oregon; Estados UnidosFil: Doorn, Stephen K.. Los Alamos National Laboratory. Los Alamos; Estados UnidosFil: Tretiak, Sergei. Los Alamos National Laboratory. Los Alamos; Estados Unido

    Population policies and education: exploring the contradictions of neo-liberal globalisation

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    The world is increasingly characterised by profound income, health and social inequalities (Appadurai, 2000). In recent decades development initiatives aimed at reducing these inequalities have been situated in a context of increasing globalisation with a dominant neo-liberal economic orthodoxy. This paper argues that neo-liberal globalisation contains inherent contradictions regarding choice and uniformity. This is illustrated in this paper through an exploration of the impact of neo-liberal globalisation on population policies and programmes. The dominant neo-liberal economic ideology that has influenced development over the last few decades has often led to alternative global visions being overlooked. Many current population and development debates are characterised by polarised arguments with strongly opposing aims and views. This raises the challenge of finding alternatives situated in more middle ground that both identify and promote the socially positive elements of neo-liberalism and state intervention, but also to limit their worst excesses within the population field and more broadly. This paper concludes with a discussion outling the positive nature of middle ground and other possible alternatives

    Economic growth in India during 1950-2015:Nehruvian socialism to market capitalism

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    Comparisons of pre and postreform economic growth in India are widely researched in the literature. This paper adds to this literature, but with a sectoral growth accounting perspective. We compare the proximate sources of economic growth in India during the 1950-1980 periods, the so-called Nehruvian socialist regime, with that of the post-1980 period, which includes the pro-business reforms in the 1980s and more aggressive pro-market reforms in the 1990s. We document two important features of India's growth dynamics. First, the overriding importance of the services sector in India's growth is not new, but it has always been the case in independent India. However, there has been a major shift in the composition of service sector growth. While the socialist regime fostered more nonmarket services, including the government sector, the market services sector flourished in the market regime, in terms of labour productivity, TFP and economic growth. Second, the economic growth in the socialist period was substantially driven by capital accumulation, except in the nonmarket services, whereas the market regime sees a combination of both productivity and capital accumulation

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    We present the first measurements of the differential cross section d sigma/dp(T)(gamma) for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapidities vertical bar y(gamma)vertical bar < 1.0 and transverse momenta 30 < p(T)(gamma) < 200 GeV. The b-quark jets are required to have p(T)(jet) > 15 GeVand vertical bar y(jet)vertical bar < 1.5. The ratio of differential production cross sections for gamma + 2 b-jets to gamma + b-jet as a function of p(T)(gamma) is also presented. The results are based on the proton-antiproton collision data at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next- to- leading order perturbative QCD calculations as well as predictions based on the k(T)- factorization approach and those from the sherpa and pythia Monte Carlo event generators

    Measurement of the top quark mass using the matrix element technique in dilepton final states

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    We present a measurement of the top quark mass in pp¯ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7  fb−1. The matrix element technique is applied to tt¯ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of tt¯ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84  GeV
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