Computing SpMV on FPGAs

There are hundreds of papers on accelerating sparse matrix vector multiplication (SpMV), however, only a handful target FPGAs. Some claim that FPGAs inherently perform inferiorly to CPUs and GPUs. FPGAs do perform inferiorly for some applications like matrix-matrix multiplication and matrix-vector multiplication. CPUs and GPUs have too much memory bandwidth and too much floating point computation power for FPGAs to compete. However, the low computations to memory operations ratio and irregular memory access of SpMV trips up both CPUs and GPUs. We see this as a leveling of the playing field for FPGAs. Our implementation focuses on three pillars: matrix traversal, multiply-accumulator design, and matrix compression. First, most SpMV implementations traverse the matrix in row-major order, but we mix column and row traversal. Second, To accommodate the new traversal the multiply accumulator stores many intermediate y values. Third, we compress the matrix to increase the transfer rate of the matrix from RAM to the FPGA. Together these pillars enable our SpMV implementation to perform competitively with CPUs and GPUs

Comparing Segmentation by Time and by Motion in Visual Search: An fMRI Investigation

Abstract Brain activity was recorded while participants engaged in a difficult visual search task for a target defined by the spatial configuration of its component elements. The search displays were segmented by time (a preview then a search display), by motion, or were unsegmented. A preparatory network showed activity to the preview display, in the time but not in the motion segmentation condition. A region of the precuneus showed (i) higher activation when displays were segmented by time or by motion, and (ii) correlated activity with larger segmentation benefits behaviorally, regardless of the cue. Additionally, the results revealed that success in temporal segmentation was correlated with reduced activation in early visual areas, including V1. The results depict partially overlapping brain networks for segmentation in search by time and motion, with both cue-independent and cue-specific mechanisms.</jats:p

A Bayesian approach for inferring the dynamics of partially observed endemic infectious diseases from space-time-genetic data

We describe a statistical framework for reconstructing the sequence of transmission events between observed cases of an endemic infectious disease using genetic, temporal and spatial information. Previous approaches to reconstructing transmission trees have assumed all infections in the study area originated from a single introduction and that a large fraction of cases were observed. There are as yet no approaches appropriate for endemic situations in which a disease is already well established in a host population and in which there may be multiple origins of infection, or that can enumerate unobserved infections missing from the sample. Our proposed framework addresses these shortcomings, enabling reconstruction of partially observed transmission trees and estimating the number of cases missing from the sample. Analyses of simulated datasets show the method to be accurate in identifying direct transmissions, while introductions and transmissions via one or more unsampled intermediate cases could be identified at high to moderate levels of case detection. When applied to partial genome sequences of rabies virus sampled from an endemic region of South Africa, our method reveals several distinct transmission cycles with little contact between them, and direct transmission over long distances suggesting significant anthropogenic influence in the movement of infected dogs

Direct thermal desorption gas chromatographic determination of toxicologically relevant concentrations of ethylene glycol in whole blood

© 2018 The Royal Society of Chemistry. A simple and rapid method involving thermal desorption gas chromatography (TD-GC) with flame ionisation detection has been successfully developed for the determination of ethylene glycol in whole blood. No sample extraction or derivatization steps were required. The conditions required for the direct determination of ethylene glycol in whole blood were optimised and require only the addition of the internal standard, 1,2-butanediol, to the sample. A 1 μL aliquot of the sample was then introduced to the thermal desorption unit, dried, and thermally desorbed directly to the gas chromatograph. A calibration curve was constructed over the concentration range of 1.0 to 200 mM and was found to be linear over the range investigated with an R2 value of 0.9997. The theoretical limit of detection based on 3σ was calculated to be 50.2 μM (3.11 mg L-1). No issues with carryover were recorded. No interferences were recorded from endogenous blood components or a number of commonly occurring alcohols. The proposed method was evaluated by carrying out replicate ethylene glycol determinations on fortified whole blood samples at the levels of 12.5 mM, 20.0 mM, 31.2 mM, 100 mM and 200 mM comparable to commonly reported blood levels in intoxications. Mean recoveries of between 84.8% and 107% were obtained with coefficients of variation of between 1.7% and 5.8%. These data suggest that the method holds promise for applications in toxicology, where a rapid, reliable method to confirm ethylene glycol poisoning is required

Training, Self-Efficacy, and Performance; a Replication Study

A conceptual replication of multiple prior IS studies was conducted with the aim of providing stronger empirical support for those results. Conducting six separate longitudinal studies, the effect of professional training on improving one’s application-specific computer self-efficacy (AS-CSE) was shown. Also in line with some prior IS studies it was shown that an application-specific measure of self-efficacy is better able to predict one’s performance in accomplishing tasks in the corresponding domain than a general computer self-efficacy (GCSE) measure. Moreover, it is shown that, regardless of the type and characteristics of the training method, individuals’ perceptions of quality of training significantly affects their AS-CSE after the training course

Exploring thematic nightmare content and associated self-harm risk

Nightmares have been shown to be robust predictors of self-harm risk, beyond depressive symptoms and hopelessness at times. However, few studies have investigated associations between nightmare content and increased self-harm risk. The present study explored associations of thematic nightmare content with history of self-harm, and risk of self-harm phenomena the morning following a nightmare. A mixed-method diary study was employed. Prospective nightmare reports were obtained from 72 participants. A total of 47 nightmare reports met inclusion criteria and were analyzed for themes using inductive thematic analysis. Chi-square and bootstrap Pearson’s correlation tests were performed to assess the associations between nightmare themes and self-harm history and risk of self-harm phenomena following a nightmare. ‘Powerlessness to Change Behavior’ was associated a history of self-harm engagement, whereas ‘Financial Hardship’ indicated reduced risk. Themes were not significantly associated with increased risk of self-harm phenomena following a nightmare. Content may be of use in detecting lifetime history of self-harm engagement particularly in populations where disclosure is seen as taboo. However, nightmare symptom severity remains better indicators of risk. Evidence for the utility of nightmare content in assessing immediate self-harm risk is presently lacking. Replication with increased power is recommended