7,159 research outputs found

    Mathematical Genesis of the Spatio-Temporal Covariance Functions

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    Obtaining new and flexible classes of nonseparable spatio-temporal covariances have resulted in a key point of research in the last years within the context of spatiotemporal Geostatistics. Approach: In general, the literature has focused on the problem of full symmetry and the problem of anisotropy has been overcome. Results: By exploring mathematical properties of positive definite functions and their close connection to covariance functions we are able to develop new spatio-temporal covariance models taking into account the problem of spatial anisotropy. Conclusion/Recommendations: The resulting structures are proved to have certain interesting mathematical properties, together with a considerable applicability.Spatial anisotropy, bernstein and complete monotone functions, spatio-temporal geostatistics, positive definite functions, space-time modeling, spatio-temporal data

    The interaction between jets and clouds in the 3CR galaxies

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    From the HST/WFPC2 3CR Snapshot Survey, data taken with the filter F555W, F702W and narrow-ramp, a set of galaxies with noticeable extended structure were selected (e.g. 3C 79, 3C 135, 3C 234, etc). All of these objects show large regions of [OIII] λ 5007˚A emission (narrow ramp filter) and the broad-band filters data show similar structures indicating the presence of strong emission in several lines over these regions. The morphology observed seems to be related (e.g. same position angle, direct overlapping or similar shape) with the radio-jet. For some candidates with these properties GMOS/Gemini spectroscopy was taken. These data (both HST direct imaging and Gemini spectroscopy) can be tested with diagnostic diagrams and total UV photons budget to understand the source of energy that is ionizing the gas. This source of ionization was commonly believed to be the UV photons emitted by the powerful active galactic nuclei (AGN), but several of these objects show clearly that shocks produced by the radio jet are the main cause of the observed gas line emission. We show in this work, the results obtained over some of these radio-galaxies: 3C 135, 3C 180, 3C 234 and 3C 284.Fil: HĂ€gele, G. F.. Universidad AutĂłnoma de Madrid; EspañaFil: Feinstein Baigorri, Carlos. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂ­sicas; ArgentinaFil: Macchetto, D. F.. Space Telescope Science Institute; Estados UnidosFil: Montero, F.. Consejo Nacional de InvestigaciĂłnes CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂ­a y FĂ­sica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomĂ­a y FĂ­sica del Espacio; Argentin

    Audience Reach Projection for the 2010 FIFA World Cup in South Africa

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    My project with the Wharton Interactive Media Initiative (WIMI) aims to model individual consumption behavior of 2010 World Cup content across ESPN\u27s media platforms. We specified and tested two Hidden Markov models on simulated data to forecast mutli-platform reach. Currently we are developing a Bayesian multivariate regression with time-varying covariates. Communicating with ESPN executives and analyzing data from the 2010 NCAA March Madness Basketball championship allowed us to identify expected reach patterns for digital platforms. The March Madness dataset also helped us understand how the World Cup data will be measured. Our next steps are to improve the specifications of the Bayesian regression model to better accommodate the correlations, heterogeneity, and non-stationarity of the expected data. Once the first two weeks of the World Cup data become available, we will apply and refine our models to forecast the digital cross-platform reach during the last three weeks of the championship. A predictive model from multi-platform reach will help ESPN better serve customers and more accurately value advertisements

    Consistency in motion event encoding across languages

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    Syntactic templates serve as schemas, allowing speakers to describe complex events in a systematic fashion. Motion events have long served as a prime example of how different languages favor different syntactic frames, in turn biasing their speakers towards different event conceptualizations. However, there is also variability in how motion events are syntactically framed within languages. Here we measure the consistency in event encoding in two languages, Spanish and Swedish. We test a dominant account in the literature, namely that variability within a language can be explained by specific properties of the events. This event-properties account predicts that descriptions of one and the same event should be consistent within a language, even in languages where there is overall variability in the use of syntactic frames. Spanish and Swedish speakers (N=84) described 32 caused motion events. While the most frequent syntactic framing in each language was as expected based on typology (Spanish: verb-framed, Swedish: satellite-framed, cf. Talmy, 2000), Swedish descriptions were substantially more consistent than Spanish descriptions. Swedish speakers almost invariably encoded all events with a single syntactic frame and systematically conveyed manner of motion. Spanish descriptions, in contrast, varied much more regarding syntactic framing and expression of manner. Crucially, variability in Spanish descriptions was not mainly a function of differences between events, as predicted by the event-properties account. Rather, Spanish variability in syntactic framing was driven by speaker biases. A similar picture arose for whether Spanish descriptions expressed manner information or not: Even after accounting for the effect of syntactic choice, a large portion of the variance in Spanish manner encoding remained attributable to differences among speakers. The results show that consistency in motion event encoding starkly differs across languages: Some languages (like Swedish) bias their speakers towards a particular linguistic event schema much more than others (like Spanish). Implications of these findings are discussed with respect to the typology of event framing, theories on the relationship between language and thought, and speech planning. In addition, the tools employed here to quantify variability can be applied to other domains of language

    Broadening of H2_2O rotational lines by collision with He atoms at low temperature

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    We report pressure broadening coefficients for the 21 electric-dipole transitions between the eight lowest rotational levels of ortho-H2_2O and para-H2_2O molecules by collisions with He at temperatures from 20 to 120 K. These coefficients are derived from recently published experimental state-to-state rate coefficients for H2_2O:He inelastic collisions, plus an elastic contribution from close coupling calculations. The resulting coefficients are compared to the available experimental data. Mostly due to the elastic contribution, the pressure broadening coefficients differ much from line to line, and increase markedly at low temperature. The present results are meant as a guide for future experiments and astrophysical observations.Comment: 2 figures, 2 table

    3-3-1 Models at Electroweak Scale

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    We show that in 3-3-1 models there exist a natural relation among the SU(3)LSU(3)_L coupling constant gg, the electroweak mixing angle ΞW\theta_W, the mass of the WW, and one of the vacuum expectation values, which implies that those models can be realized at low energy scales and, in particular, even at the electroweak scale. So that, being that symmetries realized in Nature, new physics may be really just around the corner.Comment: 10 pages, version to be published in Physics Letters
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