198 research outputs found

    Gaussian tree constraints applied to acoustic linguistic functional data

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    Evolutionary models of languages are usually considered to take the form of trees. With the development of so-called tree constraints the plausibility of the tree model assumptions can be assessed by checking whether the moments of observed variables lie within regions consistent with Gaussian latent tree models. In our linguistic application, the data set comprises acoustic samples (audio recordings) from speakers of five Romance languages or dialects. The aim is to assess these functional data for compatibility with a hereditary tree model at the language level. A novel combination of canonical function analysis (CFA) with a separable covariance structure produces a representative basis for the data. The separable-CFA basis is formed of components which emphasize language differences whilst maintaining the integrity of the observational language-groupings. A previously unexploited Gaussian tree constraint is then applied to component-by-component projections of the data to investigate adherence to an evolutionary tree. The results highlight some aspects of Romance language speech that appear compatible with an evolutionary tree model but indicates that it would be inappropriate to model all features as such

    An Improved Experimental Limit on the Electric Dipole Moment of the Neutron

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    An experimental search for an electric-dipole moment (EDM) of the neutron has been carried out at the Institut Laue-Langevin (ILL), Grenoble. Spurious signals from magnetic-field fluctuations were reduced to insignificance by the use of a cohabiting atomic-mercury magnetometer. Systematic uncertainties, including geometric-phase-induced false EDMs, have been carefully studied. Two independent approaches to the analysis have been adopted. The overall results may be interpreted as an upper limit on the absolute value of the neutron EDM of |d_n| < 2.9 x 10^{-26} e cm (90% CL).Comment: 5 pages, 2 figures. The published PRL is slightly more terse (e.g. no section headings) than this version, due to space constraints. Note a small correction-to-a-correction led to an adjustment of the final limit from 3.0 to 2.9 E-26 e.cm compared to the first version of this preprin

    Class of Service in the High Performance Storage System

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    Quality of service capabilities are commonly deployed in archival mass storage systems as one or more client-specified parameters to influence physical location of data in multi-level device hierarchies for performance or cost reasons. The capabilities of new high-performance storage architectures and the needs of data-intensive applications require better quality of service models for modern storage systems. HPSS, a new distributed, high-performance, scalable, storage system, uses a Class of Service (COS) structure to influence system behavior. The authors summarize the design objectives and functionality of HPSS and describes how COS defines a set of performance, media, and residency attributes assigned to storage objects managed by HPSS servers. COS definitions are used to provide appropriate behavior and service levels as requested (or demanded) by storage system clients. They compare the HPSS COS approach with other quality of service concepts and discuss alignment possibilities
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