37,461 research outputs found
Gaston Memorial Hospital: Driving Quality Improvement With Data, Guidelines, and Real-Time Feedback
Describes efforts to reduce variance in provider practice patterns through data analysis and benchmarking of process-of-care measures. Discusses strategies such as sharing data, feedback, and best practices in ways physicians can utilize them immediately
An Exploration of the Dynamic Relationship between Health and Cognitive Development in Adolescence
This paper is an empirical exploration of the dynamic relationship between health and cognitive development in a longitudinal data set compiled from two nationally representative cross-sections of children. Our results indicate that there is feedback both from health to cognitive development and from cognitive development to health, but the latter of these relationships is stronger. They also indicate that estimates of family background effects taken from the dynamic model -- which can be assumed to be less influenced by genetic factors are smaller than their cross-sectional counterparts, but some still remain statistically significant. The first finding calls attention to the existence of a continuing inter-action between health and cognitive development over the life cycle. The second finding suggests that nurture "matters" in cognitive development and health outcomes.
Algorithm based comparison between the integral method and harmonic analysis of the timing jitter of diode-based and solid-state pulsed laser sources
AbstractA comparison between two methods of timing jitter calculation is presented. The integral method utilizes spectral area of the single side-band (SSB) phase noise spectrum to calculate root mean square (rms) timing jitter. In contrast the harmonic analysis exploits the uppermost noise power in high harmonics to retrieve timing fluctuation. The results obtained show that a consistent timing jitter of 1.2ps is found by the integral method and harmonic analysis in gain-switched laser diodes with an external cavity scheme. A comparison of the two approaches in noise measurement of a diode-pumped Yb:KY(WO4)2 passively mode-locked laser is also shown in which both techniques give 2ps rms timing jitter
A Green's function decoupling scheme for the Edwards fermion-boson model
Holes in a Mott insulator are represented by spinless fermions in the
fermion-boson model introduced by Edwards. Although the physically interesting
regime is for low to moderate fermion density the model has interesting
properties over the whole density range. It has previously been studied at
half-filling in the one-dimensional (1D) case by numerical methods, in
particular exact diagonalization and density matrix renormalization group
(DMRG). In the present study the one-particle Green's function is calculated
analytically by means of a decoupling scheme for the equations of motion, valid
for arbitrary density in 1D, 2D and 3D with fairly large boson energy and zero
boson relaxation parameter. The Green's function is used to compute some ground
state properties, and the one-fermion spectral function, for fermion densities
n=0.1, 0.5 and 0.9 in the 1D case. The results are generally in good agreement
with numerical results obtained by DMRG and dynamical DMRG and new light is
shed on the nature of the ground state at different fillings. The Green's
function approximation is sufficiently successful in 1D to justify future
application to the 2D and 3D cases.Comment: 19 pages, 7 figures, final version with updated reference
Metallization of Fluid Hydrogen
The electrical resistivity of liquid hydrogen has been measured at the high
dynamic pressures, densities and temperatures that can be achieved with a
reverberating shock wave. The resulting data are most naturally interpreted in
terms of a continuous transition from a semiconducting to a metallic, largely
diatomic fluid, the latter at 140 GPa, (ninefold compression) and 3000 K. While
the fluid at these conditions resembles common liquid metals by the scale of
its resistivity of 500 micro-ohm-cm, it differs by retaining a strong pairing
character, and the precise mechanism by which a metallic state might be
attained is still a matter of debate. Some evident possibilities include (i)
physics of a largely one-body character, such as a band-overlap transition,
(ii) physics of a strong-coupling or many-body character,such as a Mott-Hubbard
transition, and (iii) processes in which structural changes are paramount.Comment: 12 pages, RevTeX format. Figures available on request; send mail to:
[email protected] To appear: Philosophical Transaction of the Royal
Society
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