PyFR: An Open Source Framework for Solving Advection-Diffusion Type Problems on Streaming Architectures using the Flux Reconstruction Approach

High-order numerical methods for unstructured grids combine the superior accuracy of high-order spectral or finite difference methods with the geometric flexibility of low-order finite volume or finite element schemes. The Flux Reconstruction (FR) approach unifies various high-order schemes for unstructured grids within a single framework. Additionally, the FR approach exhibits a significant degree of element locality, and is thus able to run efficiently on modern streaming architectures, such as Graphical Processing Units (GPUs). The aforementioned properties of FR mean it offers a promising route to performing affordable, and hence industrially relevant, scale-resolving simulations of hitherto intractable unsteady flows within the vicinity of real-world engineering geometries. In this paper we present PyFR, an open-source Python based framework for solving advection-diffusion type problems on streaming architectures using the FR approach. The framework is designed to solve a range of governing systems on mixed unstructured grids containing various element types. It is also designed to target a range of hardware platforms via use of an in-built domain specific language based on the Mako templating engine. The current release of PyFR is able to solve the compressible Euler and Navier-Stokes equations on grids of quadrilateral and triangular elements in two dimensions, and hexahedral elements in three dimensions, targeting clusters of CPUs, and NVIDIA GPUs. Results are presented for various benchmark flow problems, single-node performance is discussed, and scalability of the code is demonstrated on up to 104 NVIDIA M2090 GPUs. The software is freely available under a 3-Clause New Style BSD license (see www.pyfr.org)

Observations of stratospheric aerosols associated with the El Chichon eruption

Lidar observations of aerosols were carried out at Aberystwyth between Nov. 1982 and Dec. 1985 using a frequency doubled and frequency tripled Nd/Yag laser and a receiver incorporating a 1 m diameter in a Newtonian telescope configuration. In analyses of the experimental data attention is paid to the magnitude of the coefficient relating extinction and backscatter, the choice being related to the possible presence of aerosols in the upper troposphere and the atmospheric densities employed in the normalisation procedure. The aerosol loading showed marked day to day changes in early months and an overall decay was apparent only after April 1983, this decay being consistent with an e sup -1 time of about 7 months. The general decay was accompanied by a lowering of the layer but layers of aerosols were shown intermittently at heights above the main layer in winter months. The height variations of photon counts corrected for range, or of aerosol backscatter ratio, showed clear signatures of the tropopause. A strong correlation was found between the heights of the tropopause identified from the lidar measurements and from radiosonde-borne temperature measurements. A notable feature of the observations is the appearance of very sharp height gradients of backscatter ratio which seem to be produced by differential advection

THE SEASONALITY OF PATHOLOGY: A SOCIOLOGICAL ANALYSIS

This study looks at the seasonal periodicity of a number of different social pathologies, including suicide, mortality resulting from disease, the onset of physical illness, and criminal behavior. Using time-series data from the United States, for 132 consecutive months between 1965-1975, it is found that virtually all of the behaviors investigated do demonstrate some consistent pattern of seasonal incidence. A sociological theory, based upon the macro-level concept, the pace of social life, is suggested as the cause of these seasonal variations in pathology. This theory contends that, for reasons which are cultural, economic and/or climatological in nature, certain periods of the year are especially likely to be characterized by concentrations of various changes in and disruptions of people\u27s routine, day-to-day lives. Because of the need for personal and social readjustment which they entail, such periods are experienced as being potentially stressful for the members of society, resulting in an increase in the incidence of social pathology during, or immediately following, these periods of change. To operationalize the independent variable in this theory--the occurrence of important social events, and changes in the nature, frequency, and intensity of social activities and relationships--macro-level measurement device, termed the Index of the Pace of Social Life, is created. This index translates a number of the life events contained in Thomas Holmes\u27 Social Readjustment Rating Scale from the individual level of analysis to the macroscopic level, and its purpose is to provide a means of determining the relative amount of change inherent in the social events and activities characterizing a social system at any particular point in time. This theory is tested empirically, using Box-Jenkins procedures of time-series analysis and cross-correlational techniques. The results obtained provide support for the hypothesis that changes in the pace of social life within a social system act as an influence upon the temporal distribution of social pathologies within that social system, as (a) mortality resulting from disease, (b) persons missing work due to illness, (c) suicide, and (d) homicide are all found to increase simultaneous with and/or in the six months directly following increases in the Index of the Pace of Social Life

Mortality of Physicians.

n/

Measurement of the azimuthal angle dependence of inclusive jet yields in Pb+Pb collisions at √sNN=2.76 TeV with the ATLAS detector

Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δϕ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δϕ dependence of jet yields in 0.14  nb-1 of √sNN=2.76  TeV Pb+Pb collisions at the LHC for jet transverse momenta pT>45  GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with Δϕ was characterized by the parameter, v2jet, and the ratio of out-of-plane (Δϕ∼π/2) to in-plane (Δϕ∼0) yields. Nonzero v2jet values were measured in all centrality bins for pT<160  GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions

Measurement of the production cross section of prompt J/ψ mesons in association with a W± boson in pp collisions at p s = 7 TeV with the ATLAS detector

The process pp → W±J/ψ provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb-1 of p s = 7TeV pp collisions at the LHC, the first observation is made of the production of W± + prompt J/ events in hadronic collisions, using W± → μ and J/ψ → μ+μ-. A yield of 27.4±7.5 -6.5 W± + prompt J/ψ events is observed, with a statistical significance of 5.1. The production rate as a ratio to the inclusive W± boson production rate is measured, and the double parton scattering contribution to the cross section is estimated

Search for direct third-generation squark pair production in final states with missing transverse momentum and two b-jets in √s=8 TeV pp collisions with the ATLAS detector

The results of a search for pair production of supersymmetric partners of the Standard Model third-generation quarks are reported. This search uses 20.1 fb−1 of pp collisions at √s=8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The lightest bottom and top squarks ( b˜1 and t˜1 respectively) are searched for in a final state with large missing transverse momentum and two jets identified as originating from b-quarks. No excess of events above the expected level of Standard Model background is found. The results are used to set upper limits on the visible cross section for processes beyond the Standard Model. Exclusion limits at the 95 % confidence level on the masses of the third-generation squarks are derived in phenomenological supersymmetric R-parity-conserving models in which either the bottom or the top squark is the lightest squark. The b˜1 is assumed to decay via b˜1→b∼χ01 and the t˜1 via t˜1→b∼χ1± , with undetectable products of the subsequent decay of the ∼χ1± due to the small mass splitting between the ∼χ1± and the ∼χ01

Using Noninvasive Brain Measurement to Explore the Psychological Effects of Computer Malfunctions on Users during Human-Computer Interactions

In today’s technologically driven world, there is a need to better understand the ways that common computer malfunctions affect computer users. These malfunctions may have measurable influences on computer user’s cognitive, emotional, and behavioral responses. An experiment was conducted where participants conducted a series of web search tasks while wearing functional nearinfrared spectroscopy (fNIRS) and galvanic skin response sensors. Two computer malfunctions were introduced during the sessions which had the potential to influence correlates of user trust and suspicion. Surveys were given after each session to measure user’s perceived emotional state, cognitive load, and perceived trust. Results suggest that fNIRS can be used to measure the different cognitive and emotional responses associated with computer malfunctions. These cognitive and emotional changes were correlated with users’ self-report levels of suspicion and trust, and they in turn suggest future work that further explores the capability of fNIRS for the measurement of user experience during human-computer interactions