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Search Results: 1 - 10 of 146915 matches for " Marcel F Dvorak "
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Comparing the content of participation instruments using the International Classification of Functioning, Disability and Health
Vanessa K Noonan, Jacek A Kopec, Luc Noreau, Joel Singer, Anna Chan, Louise C Masse, Marcel F Dvorak
Health and Quality of Life Outcomes , 2009, DOI: 10.1186/1477-7525-7-93
Abstract: A systematic literature search was conducted to identify instruments that assess participation according to the ICF. Instruments were considered to assess participation and were included if the domains contain content from a minimum of three ICF chapters ranging from Chapter 3 Communication to Chapter 9 Community, social and civic life in the activities and participation component. The instrument content was examined by first identifying the meaningful concepts in each question and then linking these concepts to ICF categories. The content analysis included reporting the 1) ICF chapters (domains) covered in the activities and participation component, 2) relevance of the meaningful concepts to the activities and participation component and 3) context in which the activities and participation component categories are evaluated.Eight instruments were included: Impact on Participation and Autonomy, Keele Assessment of Participation, Participation Survey/Mobility, Participation Measure-Post Acute Care, Participation Objective Participation Subjective, Participation Scale (P-Scale), Rating of Perceived Participation and World Health Organization Disability Assessment Schedule II (WHODAS II). 1351 meaningful concepts were identified in the eight instruments. There are differences among the instruments regarding how participation is operationalized. All the instruments cover six to eight of the nine chapters in the activities and participation component. The P-Scale and WHODAS II have questions which do not contain any meaningful concepts related to the activities and participation component. Differences were also observed in how other ICF components (body functions, environmental factors) and health are operationalized in the instruments.Linking the meaningful concepts in the participation instruments to the ICF classification provided an objective and comprehensive method for analyzing the content. The content analysis revealed differences in how the concept of participat
Study of the Temperature Turbulences Effect upon Optical Beam in Atmospheric Optical Communication
F. Dvorak,J. Diblik
Radioengineering , 2011,
Abstract: The paper deals with the study of the effect of temperature turbulences upon the optical beam. The polarization parameters of optical radiation sources and different optical beam states of polarization have been investigated. The obtained polarization parameters are projected on the Poincare sphere by means of Stokes vectors. The optical power distribution curves of optical beams are processed into diagrams. The horizontal and vertical components of linearly and circularly polarized optical beams have been studied. The turbulence flux has vertical direction and the optical beam is propagating through an atmosphere environment with three different states of turbulence. The evaluation of the obtained data was done by means of variance and correlation functions computing. Different rates of effect of temperature turbulences upon horizontal and vertical components were found. To reduce the rate of effect the advantage of an optical beam with circular polarization has been proposed.
Modeling the Patient Journey from Injury to Community Reintegration for Persons with Acute Traumatic Spinal Cord Injury in a Canadian Centre
Argelio Santos, James Gurling, Marcel F. Dvorak, Vanessa K. Noonan, Michael G. Fehlings, Anthony S. Burns, Rachel Lewis, Lesley Soril, Nader Fallah, John T. Street, Lise Bélanger, Andrea Townson, Liping Liang, Derek Atkins
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072552
Abstract: Background A patient’s journey through the health care system is influenced by clinical and system processes across the continuum of care. Methods To inform optimized access to care and patient flow for individuals with traumatic spinal cord injury (tSCI), we developed a simulation model that can examine the full impact of therapeutic or systems interventions across the care continuum for patients with traumatic spinal cord injuries. The objective of this paper is to describe the detailed development of this simulation model for a major trauma and a rehabilitation centre in British Columbia (BC), Canada, as part of the Access to Care and Timing (ACT) project and is referred to as the BC ACT Model V1.0. Findings To demonstrate the utility of the simulation model in clinical and administrative decision-making we present three typical scenarios that illustrate how an investigator can track the indirect impact(s) of medical and administrative interventions, both upstream and downstream along the continuum of care. For example, the model was used to estimate the theoretical impact of a practice that reduced the incidence of pressure ulcers by 70%. This led to a decrease in acute and rehabilitation length of stay of 4 and 2 days, respectively and a decrease in bed utilization of 9% and 3% in acute and rehabilitation. Conclusion The scenario analysis using the BC ACT Model V1.0 demonstrates the flexibility and value of the simulation model as a decision-making tool by providing estimates of the effects of different interventions and allowing them to be objectively compared. Future work will involve developing a generalizable national Canadian ACT Model to examine differences in care delivery and identify the ideal attributes of SCI care delivery.
Utilization of Birefringent Fiber as Sensor of Temperature Field Disturbance
F. Dvorak,J. Maschke,C. Vlcek
Radioengineering , 2009,
Abstract: The paper deals with utilization of induced birefringence sensitivity to temperature field in birefringent optical fibers. The propagating optical wave and optical fibers are described by means of coherency and Jones matrices, which are decomposed into unitary matrix and spin matrices. The development of polarization caused by temperature field is interpreted on the Poincare sphere by means of MATLAB environment. The temperature sensitivity of Panda and bow-tie fiber has been measured for circular polarization excitation. Curves of intensity fluctuation caused by the temperature dependence are presented.
Knowledge loss of medical students on first year basic science courses at the university of Saskatchewan
Marcel F D'Eon
BMC Medical Education , 2006, DOI: 10.1186/1472-6920-6-5
Abstract: This study replicates previous memory decrement studies with three first year medicine basic science courses, something that was not found in the literature. It was expected that some courses would show more and some courses would show less knowledge loss.In the spring of 2004 over 20 students were recruited to retake questions from three first year courses: Immunology, physiology, and neuroanatomy. Student scores on the selected questions at the time of the final examination in May 2003 (the 'test') were compared with their scores on the questions 10 or 11 months later (the 're-test') using paired samples t -tests. A repeated-measures MANOVA was used to compare the test and re-test scores among the three courses. The re-test scores were matched with the overall student ratings of the courses and the student scores on the May 2003 examinations.A statistically significant main effect of knowledge loss (F = 297.385; p < .001) and an interaction effect by course (F = 46.081; p < .001) were found. The students' scores in the Immunology course dropped 13.1%, 46.5% in Neuroanatomy, and 16.1% in physiology. Bonferroni post hoc comparisons showed a significant difference between Neuroanatomy and Physiology (mean difference of 10.7, p = .004).There was considerable knowledge loss among medical students in the three basic science courses tested and this loss was not uniform across courses. Knowledge loss does not seem to be related to the marks on the final examination or the assessment of course quality by the students.With all the time and money spent teaching medical students one must wonder how well that investment is paying off. What portion are they retaining in memory? What are they learning? – This seems to be the central question for medical education [1]. Surely if students are not remembering what they have been taught then the effort was wasted; if students cannot make use of the knowledge they have been taught, if that knowledge becomes inert and inaccessible, th
Descriptors for point processes based on runs: the Markovian arrival process
Marcel F. Neuts
International Journal of Stochastic Analysis , 1996, DOI: 10.1155/s104895339600041x
Abstract: This paper is part of a broader investigation of properties of a point process that can be identified by imagining that the process is involved in a competition for the generation of runs of events. The general purpose of that methodology is to quantify the prevalence of gaps and bursts in realizations of the process. The Markovian arrival process (MAP) is highly versatile in qualitative behavior and its analysis is numerically tractable by matrix-analytic methods. It can therefore serve well as a benchmark process in that investigation. In this paper, we consider the MAP and a regular grid competing for runs of lengths at least r1 and r2, respectively. A run of length r in one of the processes is defined as a string of r successive events occurring without an intervening event in the other process.
A study of the stability regions in the planetary system HD 74156 - Can it host earthlike planets in habitable zones?
R. Dvorak,E. Pilat-Lohinger,B. Funk,F. Freistetter
Physics , 2003, DOI: 10.1051/0004-6361:20031404
Abstract: Using numerical methods we thoroughly investigate the dynamical stability in the region between the two planets found in HD 74156. The two planets with minimum masses 1.56 M_JUP (HD 74156b) and 7.5 M_JUP (HD 74156c), semimajor axes 0.276 AU and 3.47 AU move on quite eccentric orbits (e=0.649 and 0.395). There is a region between 0.7 and 1.4 AU which may host additional planets which we checked via numerical integrations using different dynamical models. Besides the orbital evolution of several thousands of massless regarded planets in a three-dimensional restricted 4-body problem (host star, two planets + massless bodies) we also have undertaken test computation for the orbital evolution for fictive planets with masses of 0.1, 0.3 and 1 M_JUP in the region between HD74156b and HD74156c. For direct numerical integrations up to 10^7 years we used the Lie-integrator, a method with adaptive stepsize; additionally we used the Fast Lyapunov Indicators as tool for detecting chaotic motion in this region. We emphasize the important role of the inner resonances (with the outer planet) and the outer resonances (with the inner planet) with test bodies located inside the resonances. In these two "resonance" regions almost no orbits survive. The region between the 1:5 outer resonance (0.8 AU) and the 5:1 inner resonance (1.3 AU), just in the right position for habitability, is also very unstable probably due to three-body-resonances acting there. Our results do not strictly "forbid" planets to move there, but the existence of a planet on a stable orbit between 0.8 and 1.3 AU is unlikely.
Planets in habitable zones: A study of the binary Gamma Cephei
R. Dvorak,E. Pilat-Lohinger,B. Funk,F. Freistetter
Physics , 2002, DOI: 10.1051/0004-6361:20021805
Abstract: The recently discovered planetary system in the binary GamCep was studied concerning its dynamical evolution. We confirm that the orbital parameters found by the observers are in a stable configuration. The primary aim of this study was to find stable planetary orbits in a habitable region in this system, which consists of a double star (a=21.36 AU) and a relatively close (a=2.15 AU) massive (1.7 Mjup sin i) planet. We did straightforward numerical integrations of the equations of motion in different dynamical models and determined the stability regions for a fictitious massless planet in the interval of the semimajor axis 0.5 AU < a < 1.85 AU around the more massive primary. To confirm the results we used the Fast Lyapunov Indicators (FLI) in separate computations, which are a common tool for determining the chaoticity of an orbit. Both results are in good agreement and unveiled a small island of stable motions close to 1 AU up to an inclination of about 15 deg (which corresponds to the 3:1 mean motion resonance between the two planets). Additionally we computed the orbits of earthlike planets (up to 90 earthmasses) in the small stable island and found out, that there exists a small window of stable orbits on the inner edge of the habitable zone in GamCep even for massive planets.
Role of interleukin-6 in Barrett’s esophagus pathogenesis
Katerina Dvorak,Bohuslav Dvorak
World Journal of Gastroenterology , 2013, DOI: 10.3748/wjg.v19.i15.2307
Abstract: Barrett’s esophagus (BE) is a metaplastic lesion of the distal esophagus arising as a consequence of chronic gastroesophageal reflux disease. Multiple studies show that BE is associated with increased risk of esophageal adenocarcinoma (EAC). Epidemiological studies and animal models demonstrate that chronic inflammation triggered by repeated exposure to refluxate predisposes to the development of BE and EAC. The chronic inflammation is associated with cytokine alterations. Interleukin 6 (IL-6) is a cytokine that stimulates cell proliferation and apoptosis resistance is frequently increased in different cancers. Importantly, IL-6 and transcriptional factor signal transducer and activator of transcription 3 (STAT3) that is activated by IL-6 are also increased in BE and EAC. This review critically appraises the role of IL-6/STAT3 pathway in progression of BE to EAC from the published evidence currently available.
The square-wave spectral density of a stationary renewal process
Marcel F. Neuts,H. Sitaraman
International Journal of Stochastic Analysis , 1989, DOI: 10.1155/s1048953389000109
Abstract: The power spectral density of a random square wave is a promising tool in the qualitative study of stationary point processes. This is illustrated for renewal processes and their superpositions.
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