Practical algorithms for multivariate rational approximation

17 USC 105 interim-entered record; under review.The article of record as published may be found at https://doi.org/10.1016/j.cpc.2020.107663We present two approaches for computing rational approximations to multivariate functions, motivated by their effectiveness as surrogate models for high-energy physics (HEP) applications. Our first approach builds on the Stieltjes process to efficiently and robustly compute the coefficients of the rational approximation. Our second approach is based on an optimization formulation that allows us to include structural constraints on the rational approximation (in particular, constraints demanding the absence of singularities), resulting in a semi-infinite optimization problem that we solve using an outer approximation approach. We present results for synthetic and real-life HEP data, and we compare the approximation quality of our approaches with that of traditional polynomial approximations.This work was supported by the U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research, under Contract DE-AC02-06CH11357. Support for this work was provided through the SciDAC program funded by U.S. Department of Energy, Office of Science, Advanced Scientific Computing Re search. This work was also supported by the U.S. Department of Energy through grant DE-FG02-05ER25694, and by Fermi Re search Alliance, LLC, United States of America under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research and Office of Nuclear Physics, Scientific Discovery through Advanced Computing (SciDAC) program through the FASTMath Institute under Contract No. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory

The role of the trunk control in athletic performance of a reactive change-of-direction task

Agility is vital to success in team sport competition with the trunk argued to play a key role in sport performance. This study explored the role of trunk control during a reactive change-of-direction task (R-COD) and field-based measures of athletic performance. Twenty male players completed field-based athletic performance assessments (modified Illinois agility test (mIAT), and three repetition maximum back squat (3RM)), and five countermovement jumps (CMJ) and R-CODs during which, three-dimensional ground reaction forces (GRF) and kinematics were recorded. Trunk control was assessed as the sum of the trunk relative to the pelvis range of motion in all three plane during the R-COD. Participants with the highest (HIGH; n = 7) and lowest (LOW; n = 7) trunk range of motion values were grouped. The HIGH group achieved significantly shorter mIAT time duration, higher CMJ height, and lower knee flexion angles, greater trunk lateral flexion and rotation relative to pelvis, and greater angular momentum during the R-COD compared with the LOW group. Superior athletic performance was associated with decreased trunk control (high trunk range of motion) during the R-COD. Whilst this study suggesting that trunk control is a vital component of performance, it is unknown whether this trunk control is inherent or an effect of training history, nor does not support current optimal athletic performance recommendation of decrease trunk motion during R-COD

Collaboration in the Semantic Grid: a Basis for e-Learning

The CoAKTinG project aims to advance the state of the art in collaborative mediated spaces for the Semantic Grid. This paper presents an overview of the hypertext and knowledge based tools which have been deployed to augment existing collaborative environments, and the ontology which is used to exchange structure, promote enhanced process tracking, and aid navigation of resources before, after, and while a collaboration occurs. While the primary focus of the project has been supporting e-Science, this paper also explores the similarities and application of CoAKTinG technologies as part of a human-centred design approach to e-Learning

Statics and dynamics of single DNA molecules confined in nanochannels

The successful design of nanofluidic devices for the manipulation of biopolymers requires an understanding of how the predictions of soft condensed matter physics scale with device dimensions. Here we present measurements of DNA extended in nanochannels and show that below a critical width roughly twice the persistence length there is a crossover in the polymer physics

Multilevel Modelling of Country Effects: A Cautionary Tale

Country effects on outcomes for individuals are often analysed using multilevel (hierarchical) models applied to harmonized multi-country data sets such as ESS, EU-SILC, EVS, ISSP, and SHARE. We point out problems with the assessment of country effects that appear not to be widely appreciated, and develop our arguments using Monte Carlo simulation analysis of multilevel linear and logit models. With large sample sizes of individuals within each country but only a small number of countries, analysts can reliably estimate individual-level effects but estimates of parameters summarizing country effects are likely to be unreliable. Multilevel modelling methods are no panacea

Aquilegia, Vol. 17 No. 2, April-June 1993: Newsletter of the Colorado Native Plant Society

https://epublications.regis.edu/aquilegia/1067/thumbnail.jp

Participatory politics, environmental journalism and newspaper campaigns

This is an Author's Accepted Manuscript of an article published in Journalism Studies, 13(2), 210 - 225, 2012, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/1461670X.2011.646398.This article explores the extent to which approaches to participatory politics might offer a more useful alternative to understanding the role of environmental journalism in a society where the old certainties have collapsed, only to be replaced by acute uncertainty. This uncertainty not only generates acute public anxiety about risks, it has also undermined confidence in the validity of long-standing premises about the ideal role of the media in society and journalistic professionalism. The consequence, this article argues, is that aspirations of objective reportage are outdated and ill-equipped to deal with many of the new risk stories environmental journalism covers. It is not a redrawing of boundaries that is needed but a wholesale relocation of our frameworks into approaches better suited to the socio-political conditions and uncertainties of late modernity. The exploration of participatory approaches is an attempt to suggest one way this might be done