9,018 research outputs found
A 2-year prospective study of patient-relevant outcomes in patients operated on for knee osteoarthritis with tibial osteotomy
BACKGROUND: Tibial osteotomy is a treatment for younger and/or physically active patients suffering from uni-compartmental knee osteoarthritis. The open wedge osteotomy by the hemicallotasis technique includes the use of external fixation. The use of external fixation has several advantages, as early mobilization and the opportunity for optimal correction. However, the hemicallotasis technique has also been described as a cumbersome procedure for the patient. The aim of this study was to prospectively evaluate patient-relevant outcomes during the first 2 post-operative years. Especially the treatment period, during which external fixation was used, was closely monitored. METHODS: In an uncontrolled study, fifty-eight consecutive patients, 30 men and 28 women (mean age 54 years) were operated on by the hemicallotasis technique were evaluated with the patient-relevant outcome measure Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively, during the treatment with external fixation, one week after removal of the external fixation, at 6 months, and at one and two years postoperatively. RESULTS: At the 2-year postoperative follow-up, all subscales of the KOOS were improved (p < 0.001), mostly in pain (41–80 on a 0–100 worst to best scale) and knee-related quality of life (21–61 on a 0–100 worst to best scale), compared to the preoperative status. Significant improvements in pain and other symptoms, function of daily life and quality of life were seen already during the treatment period (mean 98 ± 18 days) with the external fixation. More demanding functions such as kneeling, squatting, jumping and running, were improved first after extraction of the external fixation device and the pins. CONCLUSION: Tibial osteotomy by the hemicallotasis technique yields large improvement in self-rated pain, function and quality of life, which persists over two years. Surprisingly, large improvements occurred already during the immediate post-operative period when the external fixation was still used
Influence of adatom interactions on second layer nucleation
We develop a theory for the inclusion of adatom interactions in second layer
nucleation occurring in epitaxial growth. The interactions considered are due
to ring barriers between pairs of adatoms and binding energies of unstable
clusters. The theory is based on a master equation, which describes the time
development of microscopic states that are specified by cluster configurations
on top of an island. The transition rates are derived by scaling arguments and
tested against kinetic Monte-Carlo simulations. As an application we reanalyze
experiments to determine the step edge barrier for Ag/Pt(111).Comment: 4 pages, 4 figure
Experiments towards quantum information with trapped Calcium ions
Ground state cooling and coherent manipulation of ions in an rf-(Paul) trap
is the prerequisite for quantum information experiments with trapped ions. With
resolved sideband cooling on the optical S1/2 - D5/2 quadrupole transition we
have cooled one and two 40Ca+ ions to the ground state of vibration with up to
99.9% probability. With a novel cooling scheme utilizing electromagnetically
induced transparency on the S1/2 - P1/2 manifold we have achieved simultaneous
ground state cooling of two motional sidebands 1.7 MHz apart. Starting from the
motional ground state we have demonstrated coherent quantum state manipulation
on the S1/2 - D5/2 quadrupole transition at 729 nm. Up to 30 Rabi oscillations
within 1.4 ms have been observed in the motional ground state and in the n=1
Fock state. In the linear quadrupole rf-trap with 700 kHz trap frequency along
the symmetry axis (2 MHz in radial direction) the minimum ion spacing is more
than 5 micron for up to 4 ions. We are able to cool two ions to the ground
state in the trap and individually address the ions with laser pulses through a
special optical addressing channel.Comment: Proceedings of the ICAP 2000, Firenz
Ground state cooling, quantum state engineering and study of decoherence of ions in Paul traps
We investigate single ions of in Paul traps for quantum
information processing. Superpositions of the S electronic ground state
and the metastable D state are used to implement a qubit. Laser light
on the S D transition is used for the
manipulation of the ion's quantum state. We apply sideband cooling to the ion
and reach the ground state of vibration with up to 99.9% probability. Starting
from this Fock state , we demonstrate coherent quantum state
manipulation. A large number of Rabi oscillations and a ms-coherence time is
observed. Motional heating is measured to be as low as one vibrational quantum
in 190 ms. We also report on ground state cooling of two ions.Comment: 12 pages, 6 figures. submitted to Journal of Modern Optics, Special
Issue on Quantum Optics: Kuehtai 200
Random solids and random solidification: What can be learned by exploring systems obeying permanent random constraints?
In many interesting physical settings, such as the vulcanization of rubber,
the introduction of permanent random constraints between the constituents of a
homogeneous fluid can cause a phase transition to a random solid state. In this
random solid state, particles are permanently but randomly localized in space,
and a rigidity to shear deformations emerges. Owing to the permanence of the
random constraints, this phase transition is an equilibrium transition, which
confers on it a simplicity (at least relative to the conventional glass
transition) in the sense that it is amenable to established techniques of
equilibrium statistical mechanics. In this Paper I shall review recent
developments in the theory of random solidification for systems obeying
permanent random constraints, with the aim of bringing to the fore the
similarities and differences between such systems and those exhibiting the
conventional glass transition. I shall also report new results, obtained in
collaboration with Weiqun Peng, on equilibrium correlations and
susceptibilities that signal the approach of the random solidification
transition, discussing the physical interpretation and values of these
quantities both at the Gaussian level of approximation and, via a
renormalization-group approach, beyond.Comment: Paper presented at the "Unifying Concepts in Glass Physics" workshop,
International Centre for Theoretical Physics, Trieste, Italy (September
15-18, 1999
Continuous loading of a non-dissipative atom trap
We study theoretically a scheme in which particles from an incident beam are
trapped in a potential well when colliding with particles already present in
the well. The balance between the arrival of new particles and the evaporation
of particles from the trapped cloud leads to a steady-state that we
characterize in terms of particle number and temperature. For a cigar shaped
potential, different longitudinal and transverse evaporation thresholds can be
chosen. We show that a resonance occur when the transverse evaporation
threshold coincides with the energy of the incident particles. It leads to a
dramatic increase in phase space density with respect to the incident beam.Comment: 7 pages, 2 figure
Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBaCuO
We report the first direct observation of the oxygen-isotope
(O/O) effect on the in-plane penetration depth in
a nearly optimally doped YBaCuO film using the novel
low-energy muon-spin rotation technique. Spin polarized low energy muons are
implanted in the film at a known depth beneath the surface and precess in
the local magnetic field . This feature allows us to measure directly the
profile of the magnetic field inside the superconducting film in the
Meissner state and to make a model independent determination of .
A substantial isotope shift % at 4 K is
observed, implying that the in-plane effective supercarrier mass
is oxygen-isotope dependent with .Comment: 4 pages, 2 figure
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