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Search Results: 1 - 10 of 944 matches for " Frances Percival "
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Consultant Input in Acute Medical Admissions and Patient Outcomes in Hospitals in England: A Multivariate Analysis
Derek Bell, Adrian Lambourne, Frances Percival, Anthony A. Laverty, David K. Ward
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061476
Abstract: Recent recommendations for physicians in the UK outline key aspects of care that should improve patient outcomes and experience in acute hospital care. Included in these recommendations are Consultant patterns of work to improve timeliness of clinical review and improve continuity of care. This study used a contemporaneous validated survey compared with clinical outcomes derived from Hospital Episode Statistics, between April 2009 and March 2010 from 91 acute hospital sites in England to evaluate systems of consultant cover for acute medical admissions. Clinical outcomes studied included adjusted case fatality rates (aCFR), including the ratio of weekend to weekday mortality, length of stay and readmission rates. Hospitals that had an admitting Consultant presence within the Acute Medicine Unit (AMU, or equivalent) for a minimum of 4 hours per day (65% of study group) had a lower aCFR compared with hospitals that had Consultant presence for less than 4 hours per day (p<0.01) and also had a lower 28 day re-admission rate (p<0.01). An ‘all inclusive’ pattern of Consultant working, incorporating all the guideline recommendations and which included the minimum Consultant presence of 4 hours per day (29%) was associated with reduced excess weekend mortality (p<0.05). Hospitals with >40 acute medical admissions per day had a lower aCFR compared to hospitals with fewer than 40 admissions per day (p<0.03) and had a lower 7 day re-admission rate (p<0.02). This study is the first large study to explore the potential relationships between systems of providing acute medical care and clinical outcomes. The results show an association between well-designed systems of Consultant working practices, which promote increased patient contact, and improved patient outcomes in the acute hospital setting.
Engineering Students' Perceptions of Mobile Learning
Jennifer Percival,Nathan Percival
Lecture Notes in Engineering and Computer Science , 2008,
Abstract:
A case of a laptop learning campus: how do technology choices affect perceptions?
Jennifer Percival,Nathan Percival
Research in Learning Technology , 2009, DOI: 10.3402/rlt.v17i3.10875
Abstract: Laptop learning programs have been developed to create ubiquitous online learning environments. Given the infancy of many programs, there is little understanding of aspects of the program are perceived to provide value to faculty and students. This paper focuses on the value proposition (with respect to perceived benefits versus capital investment) for undergraduate students in a mandatory, campus-wide, comprehensive laptop learning program. Results indicate that the perceived value of the laptop for technical programs such as science, engineering, and information technology, and liberal arts programs such as business and criminology, justice, and policy studies are significantly different. This difference results in a clear need to use different laptop learning models for each type of program and that a single campus-wide model will likely prove unsatisfactory for most students. A need to better communicate the true value of industry-specific software and skills acquisition is also highlighted.
The build-up of halos within Press-Schechter theory
Will J. Percival
Physics , 2001, DOI: 10.1046/j.1365-8711.2001.04837.x
Abstract: Modelling the build-up of halos is important for linking the formation of galaxies with cosmological models. A simple model of halo growth is provided by Press-Schechter (PS) theory, where the initial field of density fluctuations is smoothed using spherically symmetric filters centred on a given position to obtain information about the likelihood of later collapse on varying scales. In this paper the predicted halo mass growth is compared for three filter shapes: Gaussian, top-hat and sharp k-space. Preliminary work is also presented analysing the build-up of halos within numerical simulations using a friends-of-friends group finder. The best-fit to the simulation mass function was obtained using PS theory with a top-hat filter. By comparing both the backwards conditional mass function, which gives the distribution of halo progenitors, and the distribution of halo mergers in time, the build-up of halos in the simulations is shown to be better fitted by PS theory with a sharp k-space filter. This strengthens previous work, which also found the build-up of halos in simulations to be well matched to PS theory with a sharp k-space filter by providing a direct comparison of different filters and by extending the statistical tools used to analyse halo mass growth. The usefulness of this work is illustrated by showing that the cosmological evolution in the proportion of halos that have undergone recent merger is predicted to be independent of mass and power spectrum and to only depend upon cosmology. Recent results from observations of field galaxies are shown to match the evolution expected, but are not sufficiently accurate to usefully distinguish between cosmological parameters.
Large Scale Structure Observations
Will J. Percival
Physics , 2013,
Abstract: Galaxy Surveys are enjoying a renaissance thanks to the advent of multi-object spectrographs on ground-based telescopes. The last 15 years have seen the fruits of this experimental advance, including the 2-degree Field Galaxy Redshift Survey (2dFGRS; Colless et al. 2003) and the Sloan Digital Sky Survey (SDSS; York et al. 2000). Most recently, the Baryon Oscillation Spectroscopic Survey (BOSS; Dawson et al. 2013), part of the SDSS-III project (Eisenstein et al. 2011), has provided the largest volume of the low-redshift Universe ever surveyed with a galaxy density useful for high-precision cosmology. This set of lecture notes looks at some of the physical processes that underpin these measurements, the evolution of measurements themselves, and looks ahead to the next 15 years and the advent of surveys such as the enhanced Baryon Oscillation Spectroscopic Survey (eBOSS), the Dark Energy Spectroscopic Instrument (DESI) and the ESA Euclid satellite mission.
Climate Change and Open Science
Ian Percival
Physics , 2013,
Abstract: Obtaining reliable answers to the major scientific questions raised by climate change in time to take appropriate action gives added urgency to the open access program.
Theoretical Properties of the Overlapping Groups Lasso
Daniel Percival
Statistics , 2011,
Abstract: We present two sets of theoretical results on the grouped lasso with overlap of Jacob, Obozinski and Vert (2009) in the linear regression setting. This method allows for joint selection of predictors in sparse regression, allowing for complex structured sparsity over the predictors encoded as a set of groups. This flexible framework suggests that arbitrarily complex structures can be encoded with an intricate set of groups. Our results show that this strategy results in unexpected theoretical consequences for the procedure. In particular, we give two sets of results: (1) finite sample bounds on prediction and estimation, and (2) asymptotic distribution and selection. Both sets of results give insight into the consequences of choosing an increasingly complex set of groups for the procedure, as well as what happens when the set of groups cannot recover the true sparsity pattern. Additionally, these results demonstrate the differences and similarities between the the grouped lasso procedure with and without overlapping groups. Our analysis shows the set of groups must be chosen with caution - an overly complex set of groups will damage the analysis.
Structured Sparse Aggregation
Daniel Percival
Statistics , 2011,
Abstract: We introduce a method for aggregating many least squares estimator so that the resulting estimate has two properties: sparsity and structure. That is, only a few candidate covariates are used in the resulting model, and the selected covariates follow some structure over the candidate covariates that is assumed to be known a priori. While sparsity is well studied in many settings, including aggregation, structured sparse methods are still emerging. We demonstrate a general framework for structured sparse aggregation that allows for a wide variety of structures, including overlapping grouped structures and general structural penalties defined as set functions on the set of covariates. We show that such estimators satisfy structured sparse oracle inequalities --- their finite sample risk adapts to the structured sparsity of the target. These inequalities reveal that under suitable settings, the structured sparse estimator performs at least as well as, and potentially much better than, a sparse aggregation estimator. We empirically establish the effectiveness of the method using simulation and an application to HIV drug resistance.
The Virtual Invigilator: A Network-based Security System for Technology-enhanced Assessments
Nathan Percival,Jennifer Percival,Clemens Martin
Lecture Notes in Engineering and Computer Science , 2008,
Abstract:
Genetics of childhood and adolescent depression: insights into etiological heterogeneity and challenges for future genomic research
Frances Rice
Genome Medicine , 2010, DOI: 10.1186/gm189
Abstract: Major depressive disorder (MDD) during childhood is relatively uncommon and the 12-month prevalence ranges from 0.5% to 3% [1,2], with an equal proportion of girls and boys affected or a slight preponderance of boys. Adolescence is a period of vulnerability for depressive disorder with first onsets often occurring during this period and subthreshold symptoms increasing markedly [3-5]. Estimates of the 12-month prevalence of depressive disorder in adolescence range from 2% to 8%, and the figure for lifetime adolescent depression is 20% [1,2,6]. In adolescence, the ratio of affected females to males is 2:1, which mirrors the pattern seen in adult life [2,6]. Adolescent subthreshold symptoms are not benign, and high levels of depressive symptoms that fall below the diagnostic threshold are associated with functional impairment [7]. Depression interferes with the ability of young people to meet their academic, economic and social potential, and is associated with a greatly increased risk of suicide and suicidal behaviour [1]. A significant proportion of depressed adolescents continue to have mental health problems and poor social outcomes in adult life [8].The criteria used to diagnose depression in children and adolescents are the same as those used in adults, with the only exception being that the Diagnostic and Statistical Manual of Mental Disorders criteria allow irritable mood instead of depressed mood as a core symptom for children and adolescents [9]. The fact that the same criteria are used to diagnose depression in childhood/adolescence and adulthood implicitly assumes similarity in the presentation of depression across developmental stages. Although very few studies have compared the phenomenology or symptom profiles of childhood/adolescent depression with that of adult depression, evidence suggests that there may be heterogeneity between childhood/adolescent and adult depression, and also between depression in childhood and adolescence. This evidence comes fr
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