1,097 research outputs found
Recent Decisions
Comments on recent decisions by William J. Daner, William T. Huston, James D. Matthews, Benedict R. Danko, John E. Lindberg, Maynard R. Bissonnette, Joseph H. Harrison, Peter J. Donahue, Louis J. Mustico, Donald John Tufts, Henry M. Shine, Jr., Arthur L. Beaudette, Luke R. Morin, John F. Mendoza, and Thomas A. Muscatello
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Tropical Intraseasonal Variability in Version 3 of the GFDL Atmosphere Model
Tropical intraseasonal variability is examined in version 3 of the Geophysical Fluid Dynamics Laboratory Atmosphere Model (AM3). In contrast to its predecessor AM2, AM3 uses a new treatment of deep and shallow cumulus convection and mesoscale clouds. The AM3 cumulus parameterization is a mass-flux-based scheme but also, unlike that in AM2, incorporates subgrid-scale vertical velocities; these play a key role in cumulus microphysical processes. The AM3 convection scheme allows multiphase water substance produced in deep cumuli to be transported directly into mesoscale clouds, which strongly influence large-scale moisture and radiation fields. The authors examine four AM3 simulations using a control model and three versions with different modifications to the deep convection scheme. In the control AM3, using a convective closure based on CAPE relaxation, both MJO and Kelvin waves are weak relative to those in observations. By modifying the convective closure and trigger assumptions to inhibit deep cumuli, AM3 produces reasonable intraseasonal variability but a degraded mean state. MJO-like disturbances in the modified AM3 propagate eastward at roughly the observed speed in the Indian Ocean but up to 2 times the observed speed in the west Pacific Ocean. Distinct differences in intraseasonal convective organization and propagation exist among the modified AM3 versions. Differences in vertical diabatic heating profiles associated with the MJO are also found. The two AM3 versions with the strongest intraseasonal signals have a more prominent “bottom heavy” heating profile leading the disturbance center and “top heavy” heating profile following the disturbance. The more realistic heating structures are associated with an improved depiction of moisture convergence and intraseasonal convective organization in AM3
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Diagnosing ocean feedbacks to the MJO: SST-modulated surface fluxes and the moist static energy budget
The composite effect of intraseasonal sea surface temperature (SST) variability on the Madden-Julian Oscillation (MJO) is studied in the context of the column integrated moist static energy (MSE) budget using data from the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I). SST fluctuations influence the Delta-q and Delta-T parts of the bulk surface latent and sensible heat flux calculations, respectively, each of which influence column MSE. Reynolds decomposition of latent and sensible heat fluxes (LH and SH) reveal that the thermodynamic perturbations modestly offset the equatorial wind-driven perturbations and MSE, but strongly offset the subtropical wind-driven perturbations and MSE. Column moistening east of MJO convection is opposed by wind-driven perturbations and supported by thermodynamic perturbations.
Impacts of intraseasonal SST fluctuations are analyzed by recomputing surface flux component terms using 61-day running-mean SST. Differences between "full SST" and "smoothed SST" projections onto MSE and its tendency yield the "SST effect" on the MJO MSE budget. Particularly in the Indian Ocean, intraseasonal SST fluctuations maintain equatorial MSE anomalies at a rate of 1%-2% per day, and damp subtropical MSE anomalies at a similar rate. Vertical advection exports 10%-20% of MSE per day, implying that the SST modulation of surface fluxes offsets roughly 10% of equatorial MSE export and amplifies by 10% the subtropical MSE export by vertical advection. SST fluctuations support MJO propagation by encouraging on-equator convection and the circulation anomalies that drive MJO propagation, and by contributing up to 10% of MSE tendencies across the Warm Pool
Geology of the Northwestern Krania Basin
The Greveniotiki Pindos Mountains of Greece showcases the tectonics
affecting the Central Mediterranean; however no detailed geological
maps have been produced of the region. In this study we present a
1:10000 geological map of Mount Orliakas and its surrounding areas,
including westernmost parts of the Pindos Ophiolite complex and the
Mesohellenic basin. We also provide new lithological, structural, and
palaeontological discussions of the region and give new evidence for
the provenance of the Kranea Formation
Early intervention for the management of acute low back pain: A single blind randomised controlled trial of biopsychosocial education, manual therapy and exercise
Design: A single blind randomised controlled trial comparing two models of care for patients with simple acute low back pain (ALBP).
Objectives: To compare two research-based models of care for ALBP, and investigate the effect of the timing of physical intervention. Summary of Background Data National guidelines offer conflicting information on the delivery of physical treatment in the management of ALBP. Review of guidelines suggests two different models of care. Direct comparisons between these models are lacking in the literature. The present study aims to compare these two approaches to the management of ALBP.
Method: Among 804 referred patients, 102 subjects met the specific admission criteria and were randomly assigned to an ‘assess/advise/treat’ group or an ‘assess/advise/wait’ group. The intervention consisted of biopsychosocial education, manual therapy and exercise. Assessment of short-term outcome enables comparison to be made between intervention and advice to stay active. Assessment of long-term outcome enables comparison to be made between early and late intervention. Study outcomes of reported pain (VAS), functional disability (RMDQ), mood (MZSRDS, MSPQ, STAIS), general health (Euroqol) and quality of life (SF-36) were assessed at baseline, six weeks, three months and six months.
Results: At six weeks, the ‘assess/advise/treat’ group demonstrated greater improvements in disability, mood, general health and quality of life than patients in the ‘assess/advise/wait’ group (p0.05). However, mood, general health and quality of life remained significantly better in the ‘assess/advise/treat’ group (p\u3c0.05).
Conclusions: At six weeks physiotherapy intervention is more effective than advice on staying active, leading to more rapid improvement in function, mood, quality of life and general health. The timing of intervention affects the progression of psychosocial features. If treatment is provided later, the same psychosocial benefits are not achieved. Therefore an \u27assess/advise/treat\u27 model of care seems to offer better outcomes than an \u27assess/advise/wait\u27 model of care
Internal resistive heating of non-metallic samples to 3000 K and >60 GPa in the diamond anvil cell
Equation of state and strength of diamond in high pressure ramp loading
Diamond is used extensively as a component in high energy density
experiments, but existing equation of state (EOS) models do not capture its
observed response to dynamic loading. In particular, in contrast with first
principles theoretical EOS models, no solid-solid phase changes have been
detected, and no general-purpose EOS models match the measured ambient
isotherm. We have performed density functional theory (DFT) calculations of the
diamond phase to ~10TPa, well beyond its predicted range of thermodynamic
stability, and used these results as the basis of a Mie-Greuneisen EOS. We also
performed DFT calculations of the elastic moduli, and calibrated an algebraic
elasticity model for use in simulations. We then estimated the flow stress of
diamond by comparison with the stress-density relation measured experimentally
in ramp-loading experiments. The resulting constitutive model allows us to
place a constraint on the Taylor-Quinney factor (the fraction of plastic work
converted to heat) from the observation that diamond does not melt on ramp
compression
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