195 research outputs found
EXPRESS: Influence of the physical effort of reminder-setting on strategic offloading of delayed intentions
Intention offloading involves the use of external reminders such as diaries, to-do lists, and digital alerts to help us remember delayed intentions. Recent studies have provided evidence for various cognitive and metacognitive factors that guide intention offloading, but little research has investigated the physical cost of reminder-setting itself. Here we present two pre-registered experiments investigating how the cost of physical effort associated with reminder-setting influences strategic intention offloading under different levels of memory load. At all memory loads, reminder-setting was reduced when it was more effortful. The ability to set reminders allowed participants to compensate for the influence of memory load on accuracy in the low-effort condition; this effect was attenuated in the high-effort condition. In addition, there was evidence that participants with less confidence in their memory abilities were more likely to set reminders. Contrary to prediction, physical effort had the greatest effect on reminder-setting at intermediate memory loads. We speculate that the physical costs of reminder-setting might have the greatest impact when participants are uncertain about their strategy choice. These results demonstrate the importance of physical effort as one of the factors relevant to cost-benefit decision-making about cognitive offloading strategies
Fast and Minimax Optimal Estimation of Low-Rank Matrices via Non-Convex Gradient Descent
We study the problem of estimating a low-rank matrix from noisy measurements,
with the specific goal of achieving minimax optimal error. In practice, the
problem is commonly solved using non-convex gradient descent, due to its
ability to scale to large-scale real-world datasets. In theory, non-convex
gradient descent is capable of achieving minimax error. But in practice, it
often converges extremely slowly, such that it cannot even deliver estimations
of modest accuracy within reasonable time. On the other hand, methods that
improve the convergence of non-convex gradient descent, through rescaling or
preconditioning, also greatly amplify the measurement noise, resulting in
estimations that are orders of magnitude less accurate than what is
theoretically achievable with minimax optimal error. In this paper, we propose
a slight modification to the usual non-convex gradient descent method that
remedies the issue of slow convergence, while provably preserving its minimax
optimality. Our proposed algorithm has essentially the same per-iteration cost
as non-convex gradient descent, but is guaranteed to converge to minimax error
at a linear rate that is immune to ill-conditioning. Using our proposed
algorithm, we reconstruct a 60 megapixel dataset for a medical imaging
application, and observe significantly decreased reconstruction error compared
to previous approaches
Soft Contribution to the Hard Ridge in Relativistic Nuclear Collisions
Nuclear collisions exhibit long-range rapidity correlations not present in
proton-proton collisions. Because the correlation structure is wide in relative
pseudorapidity and narrow in relative azimuthal angle, it is known as the
ridge. Similar ridge structures are observed in correlations of particles
associated with a jet trigger (the hard ridge) as well as correlations without
a trigger (the soft ridge). Earlier we argued that the soft ridge arises when
particles formed in an early Glasma stage later manifest transverse flow. We
extend this study to address new soft ridge measurements. We then determine the
contribution of flow to the hard ridge.Comment: 16 pages, 9 figures, includes comparison to dat
The burden of chronic obstructive pulmonary disease associated with maintenance monotherapy in the UK
Susan C Edwards,1 Sian E Fairbrother,2 Anna Scowcroft,3 Gavin Chiu,4 Andrew Ternouth,3 Brian J Lipworth5 1Department of Market Access Pricing & Outcomes Research, 2Department of Medical Affairs - Respiratory, 3Department of Market Access, 4Department of Prescription Medicine - Respiratory, Boehringer Ingelheim, Bracknell, UK; 5Asthma and Allergy Research Group, Division of Cardiovascular and Diabetes Medicine, Scottish Centre for Respiratory Research, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK Background: This study characterized a cohort of chronic obstructive pulmonary disease (COPD) patients on maintenance bronchodilator monotherapy for ≥6 months to establish their disease burden, measured by health care utilization.Methods: Data were extracted from the UK Clinical Practice Research Datalink and linked to Hospital Episode Statistics. The monotherapy period spanned the first prescription of a long-acting β2-adrenergic agonist or a long-acting muscarinic antagonist until the end of the study (December 31, 2013) or until step up to dual/triple therapy, for example, addition of another long-acting bronchodilator, an inhaled corticosteroid, or both. A minimum of four consecutive prescriptions and 6 months on continuous monotherapy were required. Patients <50 years old at first COPD diagnosis or with another significant respiratory disease before starting monotherapy were excluded. Disease burden was evaluated by measuring patients’ rate of face-to-face interactions with a health care professional (HCP), COPD-related exacerbations, hospitalizations, and referrals.Results: A cohort of 8,811 COPD patients (95% Global initiative for chronic Obstructive Lung Disease stage A/B) on maintenance monotherapy was identified between 2002 and 2013; 45% of these patients were still on monotherapy by the end of the study. Median time from first COPD diagnosis to first monotherapy prescription was 56 days, while the median time on maintenance bronchodilator monotherapy was 2 years. The median number of prescriptions was 14. On average, patients had 15 HCP interactions per year, and one in ten patients experienced a COPD exacerbation (N=8,811). One in 50 patients were hospitalized for COPD per year (n=4,848).Conclusion: The average monotherapy-treated patient had a higher than average HCP interaction rate. We also identified a large cohort of patients who were stepped up to triple therapy despite a low rate of exacerbations. The use of the new class of long-acting muscarinic antagonist/long-acting β2-adrenergic agonist fixed-dose combinations may provide a useful step-up treatment option in such monotherapy patients, before the use of inhaled corticosteroids. Keywords: COPD, UK primary care setting, bronchodilators, prescribing patterns, monotherap
Transverse Radial Flow Effects on Two- and Three-Particle Angular Correlations
We use a simple a transverse radial boost scenario coupled to PYTHIA events
to illustrate the impact radial flow may have on two- and three-particle
correlation functions measured in heavy-ion collisions. We show that modest
radial velocities can impart strong modifications to the correlation functions,
some of which may be interpreted as same side ridge and away side structure
that can mimic conical emission.Comment: 7 figures, 9 pages, Material presented in part by Pruneau at HOC 07,
Montreal, Canada Accepted for publication in Nucl Phys A (Jan 2008
Numerical simulation of a new type of cross flow tidal turbine using OpenFOAM - Part II: Investigation of turbine-to-turbine interaction
Copyright © 2013 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Renewable Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Renewable Energy, Volume 50 (2013), DOI: 10.1016/j.renene.2012.08.064Prediction of turbine-to-turbine interaction represents a significant challenge in determining the optimized power output from a tidal stream farm, and this is an active research area. This paper presents a detailed work which examines the influence of surrounding turbines on the performance of a base case (isolated turbine). The study was conducted using a new CFD based, Immersed Body Force (IBF) model, which was validated in the first paper, and an open source CFD software package OpenFOAM was used for the simulations.
The influence of the surrounding turbines was investigated using randomly chosen initial lateral and longitudinal spacing among the turbines. The initial spacing was then varied to obtain four configurations to examine the relative effect that positioning can have on the performance of the base turbine
Three-particle correlation from glasma flux tubes
We compute three particle correlations in the Glasma flux tube model of high
energy heavy ion collisions. We obtain a simple geometrical picture of these
correlations; when convoluted with final state radial flow, it results in
distinct predictions for the near side three particle correlation in central
heavy ion collisions.Comment: fixed typos and corrected some erroneous factors of 2 and 2\p
Stroke severity mediates the effect of socioeconomic disadvantage on poor outcomes among patients with intracerebral hemorrhage
BackgroundSocioeconomic deprivation drives poor functional outcomes after intracerebral hemorrhage (ICH). Stroke severity and background cerebral small vessel disease (CSVD) burden have each been linked to socioeconomic status and independently contribute to worse outcomes after ICH, providing distinct, plausible pathways for the effects of deprivation. We investigate whether admission stroke severity or cerebral small vessel disease (CSVD) mediates the effect of socioeconomic deprivation on 90-day functional outcomes.MethodsElectronic medical record data, including demographics, treatments, comorbidities, and physiological data, were analyzed. CSVD burden was graded from 0 to 4, with severe CSVD categorized as ≥3. High deprivation was assessed for patients in the top 30% of state-level area deprivation index scores. Severe disability or death was defined as a 90-day modified Rankin Scale score of 4–6. Stroke severity (NIH stroke scale (NIHSS)) was classified as: none (0), minor (1–4), moderate (5–15), moderate–severe (16–20), and severe (21+). Univariate and multivariate associations with severe disability or death were determined, with mediation evaluated through structural equation modelling.ResultsA total of 677 patients were included (46.8% female; 43.9% White, 27.0% Black, 20.7% Hispanic, 6.1% Asian, 2.4% Other). In univariable modelling, high deprivation (odds ratio: 1.54; 95% confidence interval: [1.06–2.23]; p = 0.024), severe CSVD (2.14 [1.42–3.21]; p < 0.001), moderate (8.03 [2.76–17.15]; p < 0.001), moderate–severe (32.79 [11.52–93.29]; p < 0.001), and severe stroke (104.19 [37.66–288.12]; p < 0.001) were associated with severe disability or death. In multivariable modelling, severe CSVD (3.42 [1.75–6.69]; p < 0.001) and moderate (5.84 [2.27–15.01], p < 0.001), moderate–severe (27.59 [7.34–103.69], p < 0.001), and severe stroke (36.41 [9.90–133.85]; p < 0.001) independently increased odds of severe disability or death; high deprivation did not. Stroke severity mediated 94.1% of deprivation’s effect on severe disability or death (p = 0.005), while CSVD accounted for 4.9% (p = 0.524).ConclusionCSVD contributed to poor functional outcome independent of socioeconomic deprivation, while stroke severity mediated the effects of deprivation. Improving awareness and trust among disadvantaged communities may reduce admission stroke severity and improve outcomes
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Pan-viral serology implicates enteroviruses in acute flaccid myelitis.
Since 2012, the United States of America has experienced a biennial spike in pediatric acute flaccid myelitis (AFM)1-6. Epidemiologic evidence suggests non-polio enteroviruses (EVs) are a potential etiology, yet EV RNA is rarely detected in cerebrospinal fluid (CSF)2. CSF from children with AFM (n = 42) and other pediatric neurologic disease controls (n = 58) were investigated for intrathecal antiviral antibodies, using a phage display library expressing 481,966 overlapping peptides derived from all known vertebrate and arboviruses (VirScan). Metagenomic next-generation sequencing (mNGS) of AFM CSF RNA (n = 20 cases) was also performed, both unbiased sequencing and with targeted enrichment for EVs. Using VirScan, the viral family significantly enriched by the CSF of AFM cases relative to controls was Picornaviridae, with the most enriched Picornaviridae peptides belonging to the genus Enterovirus (n = 29/42 cases versus 4/58 controls). EV VP1 ELISA confirmed this finding (n = 22/26 cases versus 7/50 controls). mNGS did not detect additional EV RNA. Despite rare detection of EV RNA, pan-viral serology frequently identified high levels of CSF EV-specific antibodies in AFM compared with controls, providing further evidence for a causal role of non-polio EVs in AFM
Heavy Quark Photoproduction in Ultra-peripheral Heavy Ion Collisions
Heavy quarks are copiously produced in ultra-peripheral heavy ion collisions.
In the strong electromagnetic fields, c c-bar and b b-bar are produced by
photonuclear and two-photon interactions; hadroproduction can occur in grazing
interactions. We present the total cross sections, quark transverse momentum
and rapidity distributions, as well as the Q Q-bar invariant mass spectra from
the three production channels. We consider AA and pA collisions at the
Relativistic Heavy Ion Collider and Large Hadron Collider. We discuss
techniques for separating the three processes and describe how the AA to pA
production ratios might be measured accurately enough to study nuclear
shadowing.Comment: Minor changes to satisfy referees and typo fixes; 52 pages including
17 figure
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