A kinematic analysis of a haptic handheld stylus in a virtual environment: a study in healthy subjects

<p>Abstract</p> <p>Background</p> <p>Virtual Reality provides new options for conducting motor assessment and training within computer-generated 3 dimensional environments. To date very little has been reported about normal performance in virtual environments. The objective of this study was to evaluate the test-retest reliability of a clinical procedure measuring trajectories with a haptic handheld stylus in a virtual environment and to establish normative data in healthy subjects using this haptic device.</p> <p>Methods</p> <p>Fifty-eight normal subjects; aged from 20 to 69, performed 3 dimensional hand movements in a virtual environment using a haptic device on three occasions within one week. Test-retest stability and standardized normative data were obtained for all subjects.</p> <p>Results</p> <p>No difference was found between test and retest. The limits of agreement revealed that changes in an individual's performance could not be detected. There was a training effect between the first test occasion and the third test occasion. Normative data are presented.</p> <p>Conclusion</p> <p>A new test was developed for recording the kinematics of the handheld haptic stylus in a virtual environment. The normative data will be used for purposes of comparison in future assessments, such as before and after training of persons with neurological deficits.</p

Modifizierung von Kunststoffeigenschaften durch Einarbeitung von Nano-Fuellstoffen

Am HITK (FS 2) mittels Flammenpyrolyse hergestellte und aufbereitete nanoskalige Metalloxide wurden am FILK (FS 1) mit dem Ziel der Erzeugung nanodisperser Systeme in extrudierten ULDPE bzw. HDPE-Folien compoundiert und verarbeitet. Im Ergebnis der Ermittlung der Zieleigenschaften wurde erkannt, dass die UV-Absorptionen der weitgehend transparenten ULDPE-Folien mit denen von unter Zusatz kommerzieller Produkte hergestellter Folien des gleichen Polymers vergleichbar sind. Beim Vergleich der Truebung im sichtbaren Licht stehen die flammenpyrolytischen Produkte geringfuegig hinter den kommerziellen Produkten zurueck. Die auf Basis nanopartikelmodifizierter HDPE-Compounds hergestellten Folien wiesen gegenueber den unmodifizierten Folien nicht den angestrebten Qualitaetssprung auf. Noch bestehende Agglomerate wirken sich auf die mechanischen Eigenschaften staerker negativ aus als auf die UV-Absorption. Positive Ansaetze fuer die Bildung hoher Wechselwirkungen brachte die Einarbeitung von der HDPE-Matrix ueber mechanisch aufbereitete waessrige Dispersionen zugefuehrten Nanopartikeln. Bei erfolgreicher Fortfuehrung der FuE-Arbeiten sind thermoplastische Compounds mit spezifischen Eigenschaften auf Basis olefinischer Standardkunststoffe erzielbar.SIGLEAvailable from TU Bergakademie, Freiberg (DE)-FILK gGmbH, under shelf-number: 200218 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Wirtschaft BMWi, Bonn (Germany); Projekttraeger Arbeitsgemeinschaft industrieller Forschungsvereinigungen Otto von Guericke e.V. AiF, Bonn, Berlin (Germany)DEGerman

Behavioral evidence for left-hemisphere specialization of motor planning

Contains fulltext : 99849.pdf (publisher's version ) (Open Access)Recent studies suggest that the left hemisphere is dominant for the planning of motor actions. This left-hemisphere specialization hypothesis was proposed in various lines of research, including patient studies, motor imagery studies, and studies involving neurophysiological techniques. However, most of these studies are primarily based on experiments involving right-hand-dominant participants. Here, we present the results of a behavioral study with left-hand-dominant participants, which follows up previous work in right-hand-dominant participants. In our experiment, participants grasped CD casings and replaced them in a different, pre-cued orientation. Task performance was measured by the end-state comfort effect, i.e., the anticipated degree of physical comfort associated with the posture that is planned to be adopted at movement completion. Both left- and right-handed participants showed stronger end-state comfort effects for their right hand compared to their left hand. These results lend behavioral support to the left-hemisphere-dominance motion-planning hypothesis

Effect of bilateral subthalamic nucleus stimulation on balance and finger control in Parkinson's disease.

Item does not contain fulltextWe aimed to quantify the effects of bilateral subthalamic nucleus (STN) stimulation in Parkinson's disease (PD) on stance and gait ("axial"motor control), and related this to effects on finger movements ("appendicular" motor control). Fourteen PD patients and 20 matched controls participated. Subjects completed several balance and gait tasks (standing with eyes open or closed, on a normal or foam surface; retropulsion test; walking with eyes closed; walking up and down stairs; Get Up and Go test). Postural control was quantified using trunk sway measurements (angle and angular velocity) in the roll and pitch directions. Subjects further performed a pinch grip reaction time task, where we measured isometric grip forces, as well as movement and reaction times. Patients were examined with STN stimulators switched on or off (order randomised across patients), always after a supramaximal levodopa dosage. STN stimulation improved postural control, as reflected by a reduced trunk sway tremor during stance, a reduced duration for all gait tasks, an increased trunk pitch velocity while rising from a chair, and improved roll stability. STN stimulation also improved finger control, as reflected by a reduced time to reach maximum grip force, without altering reaction times and maximum force levels. Improvements in finger control timing did not correlate with reduced task durations during gait. We conclude that STN stimulation affords improvement of postural control in PD, over and above optimal drug treatment. STN stimulation also provides a simultaneous effect on distal and axial motor control. Because improvements in distal and axial motor control were not correlated, we assume that these effects are mediated by stimulation of different structures within the STN

Membrangestuetzte Dehydrierung von Kohlenwasserstoffen am Beispiel des Propans. Unterprojekt A: Entwicklung wasserstoffselektiver Membranen fuer die membrangestuetzte Dehydrierung von Propan in einem Membranreaktor. Unterprojekt B: Quantifizierung des Stofftransportes durch modifizierte Keramikmembranen fuer die Simulation der membrangestuetzten Propandehydrierung. Unterauftrag: Bereitstellung geeigneter Keramikgrundkoerper hoher Flussdichte fuer die Nanofiltration Abschlussbericht

Available from TIB Hannover: F03B669 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman