278 research outputs found
Self-driven lattice-model Monte Carlo simulations of alloy thermodynamic
Monte Carlo (MC) simulations of lattice models are a widely used way to
compute thermodynamic properties of substitutional alloys. A limitation to
their more widespread use is the difficulty of driving a MC simulation in order
to obtain the desired quantities. To address this problem, we have devised a
variety of high-level algorithms that serve as an interface between the user
and a traditional MC code. The user specifies the goals sought in a high-level
form that our algorithms convert into elementary tasks to be performed by a
standard MC code. For instance, our algorithms permit the determination of the
free energy of an alloy phase over its entire region of stability within a
specified accuracy, without requiring any user intervention during the
calculations. Our algorithms also enable the direct determination of
composition-temperature phase boundaries without requiring the calculation of
the whole free energy surface of the alloy system
First-principles study of phase stability of Gd-doped EuO and EuS
Phase diagrams of isoelectronic EuGdO and EuGdS
quasi-binary alloy systems are constructed using first-principles calculations
combined with the standard cluster expansion approach and Monte-Carlo
simulations. The oxide system has a wide miscibility gap on the Gd-rich side
but forms ordered compounds on the Eu-rich side, exhibiting a deep asymmetric
convex hull in the formation enthalpy diagram. The sulfide system has no stable
compounds. The large difference in the formation enthalpies of the oxide and
sulfide compounds is due to the contribution of local lattice relaxation, which
is sensitive to the anion size. The solubility of Gd in both EuO and EuS is in
the range of 10-20% at room temperature and quickly increases at higher
temperatures, indicating that highly doped disordered solid solutions can be
produced without the precipitation of secondary phases. We also predict that
rocksalt GdO can be stabilized under appropriate experimental conditions.Comment: 14 pages, 6 figures (some with multiple panels), revtex4 with
embedded ep
Figure it : recent works by Julie Rrap, Sally Smart, Brigita Ozolins, Mary Scott, Justine Cooper
Figure it : recent works by Julie Rrap, Sally Smart, Brigita Ozolins, Mary Scott, Justine Cooper. Catalogue of exhibition held at Plimsoll Gallery, Centre for the Arts, Victoria Dock, Hobart 10 Aug.-2 Sept. 200
First demonstration of real-time 100 Gbit/s 3-Level duobinary transmission for optical interconnects
Temperature dependence of the diffuse scattering fine structure in equiatomic CuAu
The temperature dependence of the diffuse scattering fine structure from
disordered equiatomic CuAu was studied using {\it in situ} x-ray scattering. In
contrast to CuAu the diffuse peak splitting in CuAu was found to be
relatively insensitive to temperature. Consequently, no evidence for a
divergence of the antiphase length-scale at the transition temperature was
found. At all temperatures studied the peak splitting is smaller than the value
corresponding to the CuAuII modulated phase. An extended Ginzburg-Landau
approach is used to explain the temperature dependence of the diffuse peak
profiles in the ordering and modulation directions. The estimated mean-field
instability point is considerably lower than is the case for CuAu.Comment: 4 pages, 5 figure
A directly comparative two-gate case-control diagnostic accuracy study of the pure tone screen and HearCheck Screener tests for identifying hearing impairment in school children
This is the final version. Available on open access from BMJ Publishing Group via the DOI in this recordObjectives This study directly compared the accuracy of two audiometry-based tests for screening school children for hearing impairment: the currently used test, pure tone screen and a device newly applied to children, HearCheck Screener.
Design Two-gate case–control diagnostic test accuracy study.
Setting and participants Hearing impaired children (‘intended cases’) aged 4–6 years were recruited between February 2013 and August 2014 from collaborating audiology services. Children with no previously identified impairment (‘intended controls’) were recruited from Foundation and Year 1 of schools between February 2013 and June 2014 in central England. The reference standard was pure tone audiometry. Tests were administered at Nottingham Hearing Biomedical Research Unit or, for some intended cases only, in the participant’s home.
Main outcome measures Sensitivity and specificity of the pure tone screen and HearCheck tests based on pure tone audiometry result as reference standard.
Results 315 children (630 ears) were recruited; 75 from audiology services and 240 from schools. Full test and reference standard data were obtained for 600 ears; 155 ears were classified as truly impaired and 445 as truly hearing based on the pure tone audiometry assessment. Sensitivity was estimated to be 94.2% (95% CI 89.0% to 97.0%) for pure tone screen and 89.0% (95% CI 82.9% to 93.1%) for HearCheck (difference=5.2% favouring pure tone screen; 95% CI 0.2% to 10.1%; p=0.02). Estimates for specificity were 82.2% (95% CI 77.7% to 86.0%) for pure tone screen and 86.5% (95% CI 82.5% to 89.8%) for HearCheck (difference=4.3% favouring HearCheck; 95% CI0.4% to 8.2%; p=0.02).
Conclusion Pure tone screen was better than HearCheck with respect to sensitivity but inferior with respect to specificity. As avoiding missed cases is arguably of greater importance for school entry screening, pure tone screen is probably preferable in this context.National Institute for Health Research (NIHR)University of ExeterNottingham University Hospitals National Health Service (NHS) TrustCCS NHS TrustAddenbrookes Hospital, Cambridge University Hospitals Foundation TrustUniversity of Nottingha
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