2,130 research outputs found
Performance metrics for characterization of a seizure detection algorithm for offline and online use
Purpose: To select appropriate previously reported performance metrics to evaluate a new seizure detection algorithm for offline and online analysis, and thus quantify any performance variation between these metrics. Methods: Traditional offline algorithms mark out any EEG section (epoch) of a seizure (event), so that neurologists only analyze the detected and adjacent sections. Thus, offline algorithms could be evaluated using number of correctly detected events, or event-based sensitivity (SEVENT), and epoch-based specificity (percentage of incorrectly detected background epochs). In contrast, online seizure detection (especially, data selection) algorithms select for transmission only the detected EEG sections and hence need to detect the entire duration of a seizure. Thus, online algorithms could be evaluated using percentage of correctly detected seizure duration, or epoch-based sensitivity (SEPOCH), and epoch-based specificity. Here, a new seizure detection algorithm is evaluated using the selected performance metrics for epoch duration ranging from 1s to 60s. Results: For 1s epochs, the area under the event-based sensitivity-specificity curve was 0.95 whilst SEPOCH achieves 0.81. This difference is not surprising, as intuitively, detecting any epoch within a seizure is easier than detecting every epoch - especially as seizures evolve over time. For longer epochs of 30s or 60s, SEVENT falls to 0.84 and 0.82 respectively and SEPOCH reduces to 0.76. Here, decreased SEVENT shows that fewer seizures are detected, possibly due to easy-to-detect short seizure sections being masked by surrounding EEG. However, detecting one long epoch constitutes a larger percentage of a seizure than a shorter one and thus SEPOCH does not decrease proportionately. Conclusions: Traditional offline and online seizure detection algorithms require different metrics to effectively evaluate their performance for their respective applications. Using such metrics, it has been shown that a decrease in performance may be expected when an offline seizure detection algorithm (especially with short epoch duration) is used for online analysis.Accepted versio
Retaining young Catholics in the church: assessing the importance of parental example
Drawing on data from a survey conducted among 9,810 young people in England, Scotland, and Wales, this study examines parental and peer influence on church attendance among 2146 13- to 15-year-old students who identified themselves as Catholics. The data suggested that young Catholics who practise their Catholic identity by attending church do so largely because their parents are Catholic churchgoers. Moreover, young Catholic churchgoers are most likely to keep going if both mother and father are Catholic churchgoers. Among this age group of young Catholics both peer support and attending a church school are also significant, but account for little additional variance after taking parental church-going into account.
The implication from these findings for a Catholic Church strategy for ministry among children and young people within England, Scotland and Wales is that it may be wise to invest in the education and formation of Catholic parents
Christian ethos secondary schools in England and Wales: a common voice or wide diversity?
This study argues that it is the collective worldview of the students which is crucial in reflecting and shaping the ethos of schools. In order to understand the potential distinctiveness of Christian ethos schools two analyses were undertaken. The collective worldview of 2,942 students attending ten Christian ethos schools was compared with the collective worldview of 13,861 students attending 71 schools without a religious character. Then the collective worldview of 194 students attending an Anglican school that prioritised the Church’s ‘domestic’ function in education was compared with the collective worldview of 302 students attending an Anglican school that prioritised the Church’s ‘general’ function in education. The major difference occurs not between Christian ethos schools and schools without a religious character, but between Anglican schools that voice their interpretation of the Church’s mission in education differently
Performance of Large-Volume, Mean-Timed Neutron Detectors
This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit
An introduction to future truly wearable medical devices--from application to ASIC.
Accepted versio
The linear tearing instability in three dimensional, toroidal gyrokinetic simulations
Linear gyro-kinetic simulations of the classical tearing mode in
three-dimensional toroidal geometry were performed using the global gyro
kinetic turbulence code, GKW . The results were benchmarked against a
cylindrical ideal MHD and analytical theory calculations. The stability, growth
rate and frequency of the mode were investigated by varying the current
profile, collisionality and the pressure gradients. Both collision-less and
semi-collisional tearing modes were found with a smooth transition between the
two. A residual, finite, rotation frequency of the mode even in the absense of
a pressure gradient is observed which is attributed to toroidal finite
Larmor-radius effects. When a pressure gradient is present at low
collisionality, the mode rotates at the expected electron diamagnetic
frequency. However the island rotation reverses direction at high
collisionality. The growth rate is found to follow a scaling with
collisional resistivity in the semi-collisional regime, closely following the
semi-collisional scaling found by Fitzpatrick. The stability of the mode
closely follows the stability using resistive MHD theory, however a
modification due to toroidal coupling and pressure effects is seen
Discriminating between best performing features for seizure detection and data selection
Charge dependence of neoclassical and turbulent transport of light impurities on MAST
Carbon and nitrogen impurity transport coefficients are determined from gas
puff experiments carried out during repeat L-mode discharges on the Mega-Amp
Spherical Tokamak (MAST) and compared against a previous analysis of helium
impurity transport on MAST. The impurity density profiles are measured on the
low-field side of the plasma, therefore this paper focuses on light impurities
where the impact of poloidal asymmetries on impurity transport is predicted to
be negligible. A weak screening of carbon and nitrogen is found in the plasma
core, whereas the helium density profile is peaked over the entire plasma
radius.Comment: 17 pages, 7 figure
Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade
Upgraded spectroscopic hardware and an improved impurity concentration
calculation allow accurate determination of boron density in the ASDEX Upgrade
tokamak. A database of boron measurements is compared to quasilinear and
nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational
effects over a range of H-mode plasma regimes. The peaking of the measured
boron profiles shows a strong anti-correlation with the plasma rotation
gradient, via a relationship explained and reproduced by the theory. It is
demonstrated that the rotodiffusive impurity flux driven by the rotation
gradient is required for the modelling to reproduce the hollow boron profiles
at higher rotation gradients. The nonlinear simulations validate the
quasilinear approach, and, with the addition of perpendicular flow shear,
demonstrate that each symmetry breaking mechanism that causes momentum
transport also couples to rotodiffusion. At lower rotation gradients, the
parallel compressive convection is required to match the most peaked boron
profiles. The sensitivities of both datasets to possible errors is
investigated, and quantitative agreement is found within the estimated
uncertainties. The approach used can be considered a template for mitigating
uncertainty in quantitative comparisons between simulation and experiment.Comment: 19 pages, 11 figures, accepted in Nuclear Fusio
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