3,052 research outputs found
A 30-METER WALKING TEST AS A MEASURE OF CERVICAL SPONDYLOTIC MYELOPATHY SEVERITY: TEST CHARACTERISTICS AND RESULTS FROM TWO MULTICENTER COHORT STUDIES
Background Context: Cervical Spondylotic Myelopathy (CSM) is a progressive, degenerative condition and the most common cause of spinal cord dysfunction worldwide. A timed 30-meter walking test (30MWT) has previously been recommended for testing disease severity in patients with CSM because of its objectivity, quantitative nature, and ease of administration. However, very little has been reported in the literature regarding its use. Study Design/Setting: We utilized data from two prospective CSM cohort studies to analyze properties of the 30MWT test for patients with CSM. All patients had symptomatic CSM and subsequently underwent surgical decompression. Each patient completed 3 trials of the 30MWT at baseline as well as 6, 12, and 24 months following surgery. Methods: Repeated measures analysis of variance (ANOVA) was used to examine test reproducibility, and Spearman’s correlation coefficients were used to compare the results of the 30MWT to other validated scales used in the CSM population. Additionally, we used paired T-tests to assess the difference between baseline and 6-month post-operative 30MWT times. Standardized response mean was used to measure responsiveness. Results: Moderate correlation (-0.551) was seen between the 30MWT and the modified Japanese Orthopedic Association (mJOA) scale as well as the Nurick score (0.468) at baseline. Low correlation was found between the 30MWT and the NDI (0.253) as well as the physical component of the Short-Form 36 Health Survey (-0.380). Walking time did not vary significantly between the three trials at baseline (p = 0.66). At 6 months post-op, patients completed the 30MWT 9.9 seconds faster compared to baseline (p < 0.0001). Conclusions: The results from two prospective cohort studies demonstrate that the 30MWT is reproducible and moderately correlated with other validated scales used with CSM patients. Because the 30MWT is simple, quick, affordable, and assess gait parameters not accurately assessed by other standard metrics, it should be used as an ancillary test for CSM patients
Grade 1 spondylolisthesis and interspinous device placement: removal in six patients and analysis of current data
This is the published version. Information that is created by or for the US government on this site is within the public domain. Public domain information on the National Library of Medicine (NLM) Web pages may be freely distributed and copied. However, it is requested that in any subsequent use of this work, NLM be given appropriate acknowledgment.In the treatment of patients with Grade 1 spondylolisthesis, the use of interspinous devices has been controversial for nearly a decade. Several authors have suggested that Grade 1 spondylolisthesis be considered a contraindication for interspinous device placement.
Methods:
We removed interspinous devices in six symptomatic Grade 1 spondylolisthesis patients and analyzed pertinent literature.
Results:
All six patients reported an improvement in symptoms following device removal and subsequent instrumented fusion. One patient who had not been able to walk due to pain regained the ability to walk. Several articles were identified related to spondylolisthesis and interspinous devices.
Conclusions:
Regarding patients receiving interspinous devices for symptomatic lumbar spinal stenosis, several high-quality studies have failed to demonstrate a statistical difference in outcomes between patients with or without Grade 1 spondylolisthesis. Nevertheless, surgeons should have a high degree of suspicion when considering use of interspinous devices in this patient population
Universality classes in nonequilibrium lattice systems
This work is designed to overview our present knowledge about universality
classes occurring in nonequilibrium systems defined on regular lattices. In the
first section I summarize the most important critical exponents, relations and
the field theoretical formalism used in the text. In the second section I
briefly address the question of scaling behavior at first order phase
transitions. In section three I review dynamical extensions of basic static
classes, show the effect of mixing dynamics and the percolation behavior. The
main body of this work is given in section four where genuine, dynamical
universality classes specific to nonequilibrium systems are introduced. In
section five I continue overviewing such nonequilibrium classes but in coupled,
multi-component systems. Most of the known nonequilibrium transition classes
are explored in low dimensions between active and absorbing states of
reaction-diffusion type of systems. However by mapping they can be related to
universal behavior of interface growth models, which I overview in section six.
Finally in section seven I summarize families of absorbing state system
classes, mean-field classes and give an outlook for further directions of
research.Comment: Updated comprehensive review, 62 pages (two column), 29 figs
included. Scheduled for publication in Reviews of Modern Physics in April
200
Decoherence, Correlation, and Unstable Quantum States in Semiclassical Cosmology
It is demonstrated that almost any S-matrix of quantum field theory in curved
spaces posses an infinite set of complex poles (or branch cuts). These poles
can be transformed into complex eigenvalues, the corresponding eigenvectors
being Gamow vectors. All this formalism, which is heuristic in ordinary Hilbert
space, becomes a rigorous one within the framework of a properly chosen rigged
Hilbert space. Then complex eigenvalues produce damping or growing factors. It
is known that the growth of entropy, decoherence, and the appearance of
correlations, occur in the universe evolution, but only under a restricted set
of initial conditions. It is proved that the damping factors allow to enlarge
this set up to almost any initial conditions.Comment: 19 pgs. Latex fil
New Approach to Quantum Field Theory for Arbitrary Observers in Electromagnetic Backgrounds
A reformulation of fermionic QFT in electromagnetic backgrounds is presented
which uses methods analogous to those of conventional multiparticle quantum
mechanics. Emphasis is placed on the (Schr\"odinger picture) states of the
system, described in terms of Slater determinants of Dirac states, and not on
the field operator (which is superfluous in this approach). The
vacuum state `at time ' is defined as the Slater determinant of a basis
for the span of the negative spectrum of the `first quantized' Hamiltonian
, thus providing a concrete realisation of the Dirac Sea. The
general S-matrix element of the theory is derived in terms of time-dependent
Bogoliubov coefficients, demonstrating that the S-matrix follows directly from
the definition of inner product between Slater determinants. The process of
`Hermitian extension', inherited directly from conventional multiparticle
quantum mechanics, allows second quantized operators to be defined without
appealing to a complete set of orthonormal modes, and provides an extremely
straightforward derivation of the general expectation value of the theory. The
concept of `radar time', advocated by Bondi in his work on k-calculus, is used
to generalise the particle interpretation to an arbitrarily moving observer. A
definition of particle results, which depends {\it only} on the observer's
motion and the background present, not on any choice of coordinates or gauge,
or of the particle detector. We relate this approach to conventional methods by
comparing and contrasting various derivations. Our particle definition can be
viewed as a generalisation to arbitrary observers of Gibbons' approach.Comment: 36 pages, 3 figure
Starobinsky Model in Schroedinger Description
In the Starobinsky inflationary model inflation is driven by quantum
corrections to the vacuum Einstein equation. We reduce the Wheeler-DeWitt
equation corresponding to the Starobinsky model to a Schroedinger form
containing time. The Schroedinger equation is solved with a Gaussian ansatz.
Using the prescription for the normalization constant of the wavefunction given
in our previous work, we show that the Gaussian ansatz demands Hawking type
initial conditions for the wavefunction of the universe. The wormholes induce
randomness in initial states suggesting a basis for time-contained description
of the Wheeler-DeWitt equation.Comment: 19 Pages, LaTeX, no figure, gross typographical mistake
EK Eridani: the tip of the iceberg of giants which have evolved from magnetic Ap stars
We observe the slowly-rotating, active, single giant, EK Eri, to study and
infer the nature of its magnetic field directly. We used the spectropolarimeter
NARVAL at the Telescope Bernard Lyot, Pic du Midi Observatory, and the Least
Square Deconvolution method to create high signal-to-noise ratio Stokes V
profiles. We fitted the Stokes V profiles with a model of the large-scale
magnetic field. We studied the classical activity indicators, the CaII H and K
lines, the CaII infrared triplet, and H\alpha line. We detected the Stokes V
signal of EK Eri securely and measured the longitudinal magnetic field Bl for
seven individual dates spanning 60% of the rotational period. The measured
longitudinal magnetic field of EK Eri reached about 100 G and was as strong as
fields observed in RSCVn or FK Com type stars: this was found to be
extraordinary when compared with the weak fields observed at the surfaces of
slowly-rotating MS stars or any single red giant previously observed with
NARVAL. From our modeling, we infer that the mean surface magnetic field is
about 270 G, and that the large scale magnetic field is dominated by a poloidal
component. This is compatible with expectations for the descendant of a
strongly magnetic Ap star.Comment: 8 pages, 6 figures. Accepted for publication in A&
Analysis of two-player quantum games in an EPR setting using geometric algebra
The framework for playing quantum games in an Einstein-Podolsky-Rosen (EPR)
type setting is investigated using the mathematical formalism of Clifford
geometric algebra (GA). In this setting, the players' strategy sets remain
identical to the ones in the classical mixed-strategy version of the game,
which is then obtained as proper subset of the corresponding quantum game. As
examples, using GA we analyze the games of Prisoners' Dilemma and Stag Hunt
when played in the EPR type setting.Comment: 20 pages, no figure, revise
Strangeness nuclear physics: a critical review on selected topics
Selected topics in strangeness nuclear physics are critically reviewed. This
includes production, structure and weak decay of --Hypernuclei, the
nuclear interaction and the possible existence of bound
states in nuclei. Perspectives for future studies on these issues are also
outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical
Journal
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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