1,447 research outputs found
Time minimal control of batch reactors
Abstract In this article we consider a control system modelling a batch reactor in which three species X
Surgical management of multilevel lumbar spondylolysis: A case report and review of the literature
AbstractMultilevel lumbar spondylolysis accounts for less than 6% of the cases of lumbar spondylolysis and its treatment, as reported in the literature, has not been consistent. Fewer than ten cases presenting triple lumbar spondylosis have been published. We describe the case of a 33-year-old male presenting bilateral L3, L4, and L5 isthmic lysis with no spondylolisthesis or disc degeneration. The MRI and CT of the lumbar spine were decisive elements in the therapeutic choice and the surgical treatment performed was bilateral L3 and L4 isthmic repair via a combined anterior and posterior L5S1 approach. The clinical and radiological results were good at the last follow-up visit
Gait variability at fast-pace walking speed: A biomarker of mild cognitive impairment?
The interpretation of the increase in stride-to-stride variability of stride time (STV) regarding the evolution of cognitive deficits across the dementia spectrum is matter of debate.The aim of this study was to compare STV at usual and fast-pace walking speeds of MCI patients with that of cognitively healthy individuals (CHI) and Alzheimer\u27s disease (AD) patients with mild dementia, while considering the effects of potential confounders. STV while walking at usual and fast-pace walking speeds was recorded with the GAITRiteA (R) system from 116 older adults (mean age 75.6 +/- 6.5 years; 55.2% female) divided into 3 groups according to their cognitive status (44 CHI, 39 MCI patients and 33 AD patients with mild dementia). The full adjusted multiple linear regression models showed that high STV was associated with slow gait speed at usual-pace walking speed (P=0.002) and with the MCI status at fast-pace walking speed (P=0.015). High STV at fast-pace walking speed was a specific gait disturbance of MCI patients in the sample of studied participants, and thus could be used in the future as a specific biomarker of MCI patients
Physical Conditoins in Orion's Veil II: A Multi-Component Study of the Line of Sight Toward the Trapezium
Orion's Veil is an absorbing screen that lies along the line of sight to the
Orion H II region. It consists of two or more layers of gas that must lie
within a few parsecs of the Trapezium cluster. Our previous work considered the
Veil as a whole and found that the magnetic field dominates the energetics of
the gas in at least one component. Here we use high-resolution STIS UV spectra
that resolve the two velocity components in absorption and determine the
conditions in each. We derive a volume hydrogen density, 21 cm spin
temperature, turbulent velocity, and kinetic temperature, for each. We combine
these estimates with magnetic field measurements to find that magnetic energy
significantly dominates turbulent and thermal energies in one component, while
the other component is close to equipartition between turbulent and magnetic
energies. We observe molecular hydrogen absorption for highly excited v, J
levels that are photoexcited by the stellar continuum, and detect blueshifted S
III and P III. These ions must arise from ionized gas between the mostly
neutral portions of the Veil and the Trapezium and shields the Veil from
ionizing radiation. We find that this layer of ionized gas is also responsible
for He I absorption in the Veil, which resolves a 40-year-old debate on the
origin of He I absorption towards the Trapezium. Finally, we determine that the
ionized and mostly atomic layers of the Veil will collide in less than 85,000
years.Comment: 43 pages, 15 figures, to be published in Ap
Physical Conditions in Orion's Veil
Orion's veil consists of several layers of largely neutral gas lying between
us and the main ionizing stars of the Orion nebula. It is visible in 21cm H I
absorption and in optical and UV absorption lines of H I and other species.
Toward the Trapezium, the veil has two remarkable properties, high magnetic
field (~100 microGauss) and a surprising lack of molecular hydrogen given its
total hydrogen column density. Here we compute photoionization models of the
veil to establish its gas density and its distance from the Trapezium. We use a
greatly improved model of the hydrogen molecule that determines level
populations in ~1e5 rotational/vibrational levels and provides improved
estimates of molecular hydrogen destruction via the Lyman-Werner bands. Our
best fit photoionization models place the veil 1-3 pc in front of the star at a
density of 1e3-1e4 cubic centimeters. Magnetic energy dominates the energy of
non-thermal motions in at least one of the 21cm H I velocity components.
Therefore, the veil is the first interstellar environment where magnetic
dominance appears to exist. We find that the low ratio of molecular to atomic
hydrogen (< 1e-4) is a consequence of high UV flux incident upon the veil due
to its proximity to the Trapezium stars and the absence of small grains in the
region.Comment: 45 pages, 20 figures, accepted for publication in Ap
Beyond universality: parametrizing ultracold complex-mediated reactions using statistical assumptions
We have calculated accurate quantum reactive and elastic cross-sections for
the prototypical barrierless reaction D + H(=0, =0) using the
hyperspherical scattering method. The considered kinetic energy ranges from the
ultracold to the Langevin regimes. The availability of accurate results for
this system allows to test the quantum theory by Jachymski et al. [Phys. Rev.
Lett. 110, 213202 (2013)] in a nonuniversal case. The short range reaction
probability is rationalized using statistical model assumptions and related to
a statistical factor. This provides a means to estimate one of the parameters
that characterizes ultracold processes from first principles. Possible
limitations of the statistical model are considered
Aggressive behavior after traumatic brain injury
INTRODUCTION: In cases of agitation and aggressive behavior after severe traumatic brain injury (TBI), the benefits/risks ratio of pharmacological treatments remains unclear. A qualitative analysis of clinical situations could highlight the relevance of psychotherapy care.CASE REPORT: In January 2005, this 24-year-old patient sustained severe traumatic brain injury (Glasgow at 4/15), with bilateral frontotemporal injury and temporal extradural hematoma. On the third day, a temporal lobectomy was performed. The patient\u27s evolution showed severe neurobehavioral disorders, with agitation and aggressive behavior towards family members and medical caregivers. Maximum doses of antipsychotic drugs brought no improvement. Antidepressant medication improved social contact. Several stays in the psychiatric unit, where institutionalized and psychotherapy care were implemented, showed systematically a real improvement of the behavioral disorders, increased participation in group activities and the ability to walk around alone in a closed environment. DISCUSSION/CONCLUSION: Aggressive behavior can unveil organic brain injuries, depressive syndrome as well as iatrogenic nature of the environment. This clinical case is based on the fact that antipsychotic drugs, aside from their sedative effect, are not the proper treatment for agitation following traumatic brain injury. This case also highlights how management of behavioral disorders following TBI should not be based on pharmacological treatments only but instead should focus on multidisciplinary strategies of care
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