1,820 research outputs found
Screening Seniors for Risk of Functional Decline: Results of a Survey in Family Practice
To measure functional status, determine risk of functional decline and assess consistency between responses and standardized instruments. Design: A mailed survey which measured functional impairment, recent hospitalization and bereavement. A positive response on at least one of these factors indicated that the individual was “at risk” for functional decline. A random sample (n=73) of “at risk” subjects (specifically, family practice patients aged 70 and older) were assessed by a nurse. Results: The response rate was 89% (369/415), 59% of seniors were female and the mean age was 77.1 (SD=5.5) years. Self-reported risk, based on activities of daily living (ADLs), was associated with impairment in at least one basic ADL (p\u3c0.0005) using a standardized instrument. The positive predictive value of the survey for ADL impairment was 65%. Conclusion: Response to a mailed survey was high and self-reported ADL risks were consistent with findings from standardized assessment tools
An efficient k.p method for calculation of total energy and electronic density of states
An efficient method for calculating the electronic structure in large systems
with a fully converged BZ sampling is presented. The method is based on a
k.p-like approximation developed in the framework of the density functional
perturbation theory. The reliability and efficiency of the method are
demostrated in test calculations on Ar and Si supercells
Neurophysiology
Contains reports on four research projects.Bell Telephone Laboratories, Inc.U.S. Air Force (Aeronautical Systems Division) under Contract AF 33(615)-1747National Aeronautics and Space Administration (Grant NsG-496)National Institutes of Health (Grant MH-04737-05)National Science Foundation (Grant GP-2495)The Teagle Foundation, Inc
Post-aragonite phases of CaCO at lower mantle pressures
The stability, structure and properties of carbonate minerals at lower mantle
conditions has significant impact on our understanding of the global carbon
cycle and the composition of the interior of the Earth. In recent years, there
has been significant interest in the behavior of carbonates at lower mantle
conditions, specifically in their carbon hybridization, which has relevance for
the storage of carbon within the deep mantle. Using high-pressure synchrotron
X-ray diffraction in a diamond anvil cell coupled with direct laser heating of
CaCO using a CO laser, we identify a crystalline phase of the
material above 40 GPa corresponding to a lower mantle depth of around 1,000
km which has first been predicted by \textit{ab initio} structure
predictions. The observed carbon hybridized species at 40 GPa is
monoclinic with symmetry and is stable up to 50 GPa, above which it
transforms into a structure which cannot be indexed by existing known phases. A
combination of \textit{ab initio} random structure search (AIRSS) and
quasi-harmonic approximation (QHA) calculations are used to re-explore the
relative phase stabilities of the rich phase diagram of CaCO. Nudged
elastic band (NEB) calculations are used to investigate the reaction mechanisms
between relevant crystal phases of CaCO and we postulate that the mineral
is capable of undergoing - hybridization change purely in the
structure forgoing the accepted post-aragonite structure.Comment: 12 pages, 8 figure
Neurophysiology
Contains reports on three research projects.National Institutes of Health (Grant 5 RO1 NB-04985-03)Instrumentation Laboratory under the auspices of DSR Project 55-257Bioscience Division of National Aeronautics and Space Administration through Contract NSR 22-009-138Bell Telephone Laboratories, Inc. (Grant)The Teagle Foundation, Inc. (Grant)U. S. Air Force (Aerospace Medical Division) under Contract AF33(615)-388
Structures and stability of calcium and magnesium carbonates at mantle pressures
Ab initio random structure searching (AIRSS) and density functional theory
methods are used to predict structures of calcium and magnesium carbonate
(CaCO and MgCO) at high pressures. We find a previously unknown
CaCO structure which is more stable than the aragonite and "post aragonite"
phases in the range 32--48 GPa. At pressures from 67 GPa to well over 100 GPa
the most stable phase is a previously unknown CaCO structure of the
pyroxene type with fourfold coordinated carbon atoms. We also predict a stable
structure of MgCO in the range 85--101 GPa. Our results lead to a revision
of the phase diagram of CaCO over more than half the pressure range
encountered within the Earth's mantle, and smaller changes to the phase diagram
of MgCO. We predict CaCO to be more stable than MgCO in the Earth's
mantle above 100 GPa, and that CO is not a thermodynamically stable
compound under deep mantle conditions. Our results have significant
implications for understanding the Earth's deep carbon cycle.We acknowledge financial support from the Engineering and Physical Sciences Research Council United Kingdom (EPSRC) of the United Kingdom.This is the author accepted manuscript. The final version is available from APS via http://dx.doi.org/10.1103/PhysRevB.91.10410
Critical resonance in the non-intersecting lattice path model
We study the phase transition in the honeycomb dimer model (equivalently,
monotone non-intersecting lattice path model). At the critical point the system
has a strong long-range dependence; in particular, periodic boundary conditions
give rise to a ``resonance'' phenomenon, where the partition function and other
properties of the system depend sensitively on the shape of the domain.Comment: 28 pages, 6 figures. v4 has changes suggested by refere
Neurophysiology
Contains reports on four research projects.National Science Foundation (Grant G-16526)National Institutes of Health (Grants MH-04737-03 and NB-04985-01)United States Air Force, Aeronautical Systems Division (Contract AF33(616)-7783)United States Air Force (Contract AF19(604)-6619), administered by Montana State CollegeNational Aeronautics and Space Administration (Grant NsG-496)Teagle Foundation, IncorporatedBell Telephone Laboratories, Incorporate
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