886 research outputs found
Pursuing More Aggressive Timelines in the Surgical Treatment of Traumatic Spinal Cord Injury (TSCI): A Retrospective Cohort Study with Subgroup Analysis
Background: The optimal timing of surgical therapy for traumatic spinal cord injury (TSCI) remains unclear. The purpose of this study is to evaluate the impact of “ultra-early” (<4 h) versus “early” (4–24 h) time from injury to surgery in terms of the likelihood of neurologic recovery. Methods: The effect of surgery on neurological recovery was investigated by comparing the assessed initial and final values of the American Spinal Injury Association (ASIA) Impairment Scale (AIS). A post hoc analysis was performed to gain insight into different subgroup regeneration behaviors concerning neurological injury levels. Results: Datasets from 69 cases with traumatic spinal cord injury were analyzed. Overall, 19/46 (41.3%) patients of the “ultra-early” cohort saw neurological recovery compared to 5/23 (21.7%) patients from the “early” cohort (p = 0.112). The subgroup analysis revealed differences based on the neurological level of injury (NLI) of a patient. An optimal cutpoint for patients with a cervical lesion was estimated at 234 min. Regarding the prediction of neurological improvement, sensitivity was 90.9% with a specificity of 68.4%, resulting in an AUC (area under the curve) of 84.2%. In thoracically and lumbar injured cases, the estimate was lower, ranging from 284 (thoracic) to 245 min (lumbar) with an AUC of 51.6% and 54.3%. Conclusions: Treatment within 24 h after TSCI is associated with neurological recovery. Our hypothesis that intervention within 4 h is related to an improvement in the neurological outcome was not confirmed in our collective. In a clinical context, this suggests that after TSCI there is a time frame to get the right patient to the right hospital according to advanced trauma life support (ATLS) guidelines
Is Quantum Chaos Weaker Than Classical Chaos?
We investigate chaotic behavior in a 2-D Hamiltonian system - oscillators
with anharmonic coupling. We compare the classical system with quantum system.
Via the quantum action, we construct Poincar\'{e} sections and compute Lyapunov
exponents for the quantum system. We find that the quantum system is globally
less chaotic than the classical system. We also observe with increasing energy
the distribution of Lyapunov exponts approaching a Gaussian with a strong
correlation between its mean value and energy.Comment: text (LaTeX) + 7 figs.(ps
The Pennsylvania Dutchman Vol. 8, No. 4
● Such Fancy Boxes, Yet ● Dried Corn ● Pennsylvania Dutch Cooking is Corny ● The Amish at Play ● Colonial Button Mold ● Illness and Cure of Domestic Animals Among the Pennsylvania Dutch ● Pennsylvania Dutch Pioneershttps://digitalcommons.ursinus.edu/dutchmanmag/1011/thumbnail.jp
The Pennsylvania Dutchman Vol. 8, No. 3
● The Dutch Touch in Iron ● The Pennsylvania Dutch Village ● Five June Days ● On an Amish Farm ● Traveling Pennsylvanians ● The Trail of the Stone Arched Bridges in Berks County ● Displaced Dutchmen Crave Shoo-flies ● Florence Starr Taylor ● Pennsylvania Dutch Pioneers ● Zinzendorf and Moravian Research ● Sheep in Dutchlandhttps://digitalcommons.ursinus.edu/dutchmanmag/1010/thumbnail.jp
The Dutchman Vol. 6, No. 2
● Spatterware ● That\u27s a Lot of Boloney ● A Dutch Touch ● Birds in Dutchland ● Cornelius Weygandt Day ● Brick-end Barns ● Hardly Bigger Than a Peanut ● Pennsylvania Dutch Pioneers ● Sycamores in Dutchland ● The Zehn-uhr Schtickhttps://digitalcommons.ursinus.edu/dutchmanmag/1001/thumbnail.jp
The Dutchman Vol. 6, No. 1
● Editorial ● Somerset County Decorated Barns ● Butter Molds ● Restaurants, too, Go Dutch ● The Hostetter Fractur Collection ● Bindnagle\u27s Church ● The Harry S. High Folk Art Collection ● Lebanon Valley Date Stones ● Of Bells and Bell Towers ● John Durang, the First Native American Dancer ● Stoffel Rilbps\u27 Epistle ● The First Singing of Our National Anthem ● Pennsylvania Dutch Pioneershttps://digitalcommons.ursinus.edu/dutchmanmag/1000/thumbnail.jp
Approach to ergodicity in quantum wave functions
According to theorems of Shnirelman and followers, in the semiclassical limit
the quantum wavefunctions of classically ergodic systems tend to the
microcanonical density on the energy shell. We here develop a semiclassical
theory that relates the rate of approach to the decay of certain classical
fluctuations. For uniformly hyperbolic systems we find that the variance of the
quantum matrix elements is proportional to the variance of the integral of the
associated classical operator over trajectory segments of length , and
inversely proportional to , where is the Heisenberg
time, being the mean density of states. Since for these systems the
classical variance increases linearly with , the variance of the matrix
elements decays like . For non-hyperbolic systems, like Hamiltonians
with a mixed phase space and the stadium billiard, our results predict a slower
decay due to sticking in marginally unstable regions. Numerical computations
supporting these conclusions are presented for the bakers map and the hydrogen
atom in a magnetic field.Comment: 11 pages postscript and 4 figures in two files, tar-compressed and
uuencoded using uufiles, to appear in Phys Rev E. For related papers, see
http://www.icbm.uni-oldenburg.de/icbm/kosy/ag.htm
- …