9,623 research outputs found
Review of ride quality technology needs of industry and user groups
A broad survey of ride quality technology state-of-the-art and a review of user evaluation of this technology were conducted. During the study 17 users of ride quality technology in 10 organizations representing land, marine and air passenger transportation modes were interviewed. Interim results and conclusions of this effort are reported
User evaluation of ride technology research
The 23 organizations queried represent government, carrier, and manufacturing interests in air, marine, rail, and surface transportation systems. Results indicate a strong need for common terminology and data analysis/reporting techniques. The various types of ride criteria currently in use are discussed, particularly in terms of their respective data base requirements. A plan of action is proposed for fulfilling the ride technology needs identified by this study
Absence of superconductivity in the half-filled band Hubbard model on the anisotropic triangular lattice
We report exact calculations of magnetic and superconducting pair-pair
correlations for the half-filled band Hubbard model on an anisotropic
triangular lattice. Our results for the magnetic phases are similar to those
obtained with other techniques. The superconducting pair-pair correlations at
distances beyond nearest neighbor decrease monotonically with increasing
Hubbard interaction U for all anisotropy, indicating the absence of
frustration-driven superconductivity within the model.Comment: 4 pages, 4 EPS figure
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Developing theory-informed interventions to implement evidence into practice: a systematic approach using the Theoretical Domains Framework
Background: There is little systematic operational guidance about how best to develop complex interventions to reduce the gap between practice and evidence. This article is one in a series of articles documenting the development and use of the Theoretical Domains Framework (TDF) to advance the science of implementation research.
Methods: The intervention was developed considering three main components: theory, evidence, and practical issues. We used a four-step approach, consisting of guiding questions, to direct the choice of the most appropriate components of an implementation intervention: Who needs to do what, differently? Using a theoretical framework, which barriers and enablers need to be addressed? Which intervention components (behaviour change techniques and mode(s) of delivery) could overcome the modifiable barriers and enhance the enablers? And how can behaviour change be measured and understood?
Results: A complex implementation intervention was designed that aimed to improve acute low back pain management in primary care. We used the TDF to identify the barriers and enablers to the uptake of evidence into practice and to guide the choice of intervention components. These components were then combined into a cohesive intervention. The intervention was delivered via two facilitated interactive small group workshops. We also produced a DVD to distribute to all participants in the intervention group. We chose outcome measures in order to assess the mediating mechanisms of behaviour change.
Conclusions: We have illustrated a four-step systematic method for developing an intervention designed to change clinical practice based on a theoretical framework. The method of development provides a systematic framework that could be used by others developing complex implementation interventions. While this framework should be iteratively adjusted and refined to suit other contexts and settings, we believe that the four-step process should be maintained as the primary framework to guide researchers through a comprehensive intervention development process
Spin Bose-Metal and Valence Bond Solid phases in a spin-1/2 model with ring exchanges on a four-leg triangular ladder
We study a spin-1/2 system with Heisenberg plus ring exchanges on a four-leg
triangular ladder using the density matrix renormalization group and Gutzwiller
variational wave functions. Near an isotropic lattice regime, for moderate to
large ring exchanges we find a spin Bose-metal phase with a spinon Fermi sea
consisting of three partially filled bands. Going away from the triangular
towards the square lattice regime, we find a staggered dimer phase with dimers
in the transverse direction, while for small ring exchanges the system is in a
featureless rung phase. We also discuss parent states and a possible phase
diagram in two dimensions.Comment: 4 pages, 5 figures, v3 is the print versio
Phase diagram of the one-dimensional Holstein model of spinless fermions
The one-dimensional Holstein model of spinless fermions interacting with
dispersionless phonons is studied using a new variant of the density matrix
renormalisation group. By examining various low-energy excitations of finite
chains, the metal-insulator phase boundary is determined precisely and agrees
with the predictions of strong coupling theory in the anti-adiabatic regime and
is consistent with renormalisation group arguments in the adiabatic regime. The
Luttinger liquid parameters, determined by finite-size scaling, are consistent
with a Kosterlitz-Thouless transition.Comment: Minor changes. 4 pages, 4 figures. To appear in Physical Review
Letters 80 (1998) 560
Electric-Field-Induced Mott Insulating States in Organic Field-Effect Transistors
We consider the possibility that the electrons injected into organic
field-effect transistors are strongly correlated. A single layer of acenes can
be modelled by a Hubbard Hamiltonian similar to that used for the
kappa-(BEDT-TTF)(2)X family of organic superconductors. The injected electrons
do not necessarily undergo a transition to a Mott insulator state as they would
in bulk crystals when the system is half-filled. We calculate the fillings
needed for obtaining insulating states in the framework of the slave-boson
theory and in the limit of large Hubbard repulsion, U. We also suggest that
these Mott states are unstable above some critical interlayer coupling or
long-range Coulomb interaction.Comment: 9 pages, 7 figure
Magnetoresistance and magnetic breakdown in the quasi-two-dimensional conductors (BEDT-TTF)MHg(SCN)[M=K,Rb,Tl]
The magnetic field dependence of the resistance of
(BEDT-TTF)MHg(SCN)[M=K,Rb,Tl] in the density-wave phase is explained in
terms of a simple model involving magnetic breakdown and a reconstructed Fermi
surface. The theory is compared to measurements in pulsed magnetic fields up to
51 T. The value implied for the scattering time is consistent with independent
determinations. The energy gap associated with the density-wave phase is
deduced from the magnetic breakdown field. Our results have important
implications for the phase diagram.Comment: 5 pages, RevTeX + epsf, 3 figures. To appear in Physical Review B,
Rapid Communications, September 15, 199
Severe Lumbar Disability Is Associated With Decreased Psoas Cross-Sectional Area in Degenerative Spondylolisthesis
Study Design: Retrospective cohort. Objectives: Alterations in lumbar paraspinal muscle cross-sectional area (CSA) may correlate with lumbar pathology. The purpose of this study was to compare paraspinal CSA in patients with degenerative spondylolisthesis and severe lumbar disability to those with mild or moderate lumbar disability, as determined by the Oswestry Disability Index (ODI). Methods: We retrospectively reviewed the medical records of 101 patients undergoing lumbar fusion for degenerative spondylolisthesis. Patients were divided into ODI score ≤40 (mild/moderate disability, MMD) and ODI score \u3e40 (severe disability, SD) groups. The total CSA of the psoas and paraspinal muscles were measured on preoperative magnetic resonance imaging (MRI). Results: There were 37 patients in the SD group and 64 in the MMD group. Average age and body mass index were similar between groups. For the paraspinal muscles, we were unable to demonstrate any significant differences in total CSA between the groups. Psoas muscle CSA was significantly decreased in the SD group compared with the MMD group (1010.08 vs 1178.6 mm2, P =.041). Multivariate analysis found that psoas CSA in the upper quartile was significantly protective against severe disability (P =.013). Conclusions: We found that patients with severe lumbar disability had no significant differences in posterior lumbar paraspinal CSA when compared with those with mild/moderate disability. However, severely disabled patients had significantly decreased psoas CSA, and larger psoas CSA was strongly protective against severe disability, suggestive of a potential association with psoas atrophy and worsening severity of lumbar pathology. © The Author(s) 2018
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