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Normal Walking (normal + walking)
Selected AbstractsOptimization-based dynamic human walking prediction: One step formulationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2009Yujiang Xiang Abstract A new methodology is introduced in this work to simulate normal walking using a spatial digital human model. The proposed methodology is based on an optimization formulation that minimizes the dynamic effort of people during walking while considering associated physical and kinematical constraints. Normal walking is formulated as a symmetric and cyclic motion. Recursive Lagrangian dynamics with analytical gradients for all the constraints and objective function are incorporated in the optimization process. Dynamic balance of the model is enforced by direct use of the equations of motion. In addition, the ground reaction forces are calculated using a new algorithm that enforces overall equilibrium of the human skeletal model. External loads on the human body, such as backpacks, are also included in the formulation. Simulation results with the present methodology show good correlation with the experimental data obtained from human subjects and the existing literature. Copyright © 2009 John Wiley & Sons, Ltd. [source] Facilitation of corticospinal excitability in the tibialis anterior muscle during robot-assisted passive stepping in humansEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2009Kiyotaka Kamibayashi Abstract Although phasic modulation of the corticospinal tract excitability to the lower limb muscles has been observed during normal walking, it is unclear to what extent afferent information induced by walking is related to the modulation. The purpose of this study was to test the corticospinal excitability to the lower limb muscles by using transcranial magnetic stimulation (TMS) and transcranial electrical stimulation of the motor cortex while 13 healthy subjects passively stepped in a robotic driven-gait orthosis. Specifically, to investigate the effect of load-related afferent inputs on the corticospinal excitability during passive stepping, motor evoked potentials (MEPs) in response to the stimulation were compared between two passive stepping conditions: 40% body weight unloading on a treadmill (ground stepping) and 100% body weight unloading in the air (air stepping). In the rectus femoris, biceps femoris and tibialis anterior (TA) muscles, electromyographic activity was not observed throughout the step cycle in either stepping condition. However, the TMS-evoked MEPs of the TA muscle at the early- and late-swing phases as well as at the early-stance phase during ground stepping were significantly larger than those observed during air stepping. The modulation pattern of the transcranial electrical stimulation-evoked MEPs was similar to that of the TMS-evoked MEPs. These results suggest that corticospinal excitability to the TA is facilitated by load-related afferent inputs. Thus, these results might be consistent with the notion that load-related afferent inputs play a significant role during locomotor training for gait disorders. [source] Optimization-based dynamic human walking prediction: One step formulationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2009Yujiang Xiang Abstract A new methodology is introduced in this work to simulate normal walking using a spatial digital human model. The proposed methodology is based on an optimization formulation that minimizes the dynamic effort of people during walking while considering associated physical and kinematical constraints. Normal walking is formulated as a symmetric and cyclic motion. Recursive Lagrangian dynamics with analytical gradients for all the constraints and objective function are incorporated in the optimization process. Dynamic balance of the model is enforced by direct use of the equations of motion. In addition, the ground reaction forces are calculated using a new algorithm that enforces overall equilibrium of the human skeletal model. External loads on the human body, such as backpacks, are also included in the formulation. Simulation results with the present methodology show good correlation with the experimental data obtained from human subjects and the existing literature. Copyright © 2009 John Wiley & Sons, Ltd. [source] Millipede phylogeny revisited in the light of the enigmatic order SiphoniulidaJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2003P. Sierwald Abstract The discovery of six specimens of the enigmatic order Siphoniulida, including for the first time males, prompted a modern re-analysis of current phylogenetic schemes for the class Diplopoda derived from traditional morphological and developmental characters. The data matrix was constructed and analysed using paup. The resulting phylogenetic hypotheses corroborated the longest standing, traditional classification, but also demonstrated clearly that more characters must be included to reach a better resolution. Recent alternative phylogenetic hypotheses and classifications are discussed in the light of the current analysis. The validity of a putative helminthomorph synapomorphy, the location of male gonopods on the 7th body ring, is discussed. Scanning electron microscopy corroborated morphological characters already described for the Siphoniulida: modified anterior legs, an apparently legless 3rd body ring, pyriform head, antennae with clavate setae, and absence of ozopores. The highly modified gonopods of the Siphoniulida are described for the first time; only the anterior legs of the 7th ring are modified into gonopods, the posterior legs of this ring are developed as normal walking legs. The gnathochilarium differs from the Colobognatha and consists of well-developed stipites with palps, elongated lingual plates with palps and a narrow central sclerite, most likely the mentum. Structures on the epiproct may possibly be spinnerets. Despite the discovery of adult males, the Siphoniulida are still considered Helminthomorpha incertae sedis . Zusammenfassung Die Entdeckung von 6 Exemplaren der ungewöhnlichen Ordnung Siphoniulida, einschließlich der ersten Männchen, erforderte eine Neu-Analyse der derzeitig diskutierten, morphologisch begründeten Klassifikationen der Klasse Diplopoda. Die erstellte Datenmatrize wurde in PAUP analysiert. Die sich ergebenden phylogenetischen Hypothesen bestätigen in wesentlichen die früheren, traditionellen Klassifikationsschemata; allerdings zeigt diese Analyse auch, dass die Merkmalsbasis erweitert werden muss, um eine höhere Auflösung zu erreichen. Neuere, abweichende phylogenetische Klassifikationen und Kladogramme werden unter Berücksichtigung der jetzigen Analyse verglichen. Die Gültigkeit einer der vorgeschlagenen Apomorphien für das Taxon Helminthomorpha, die Position der Gonopden am 7. Körperring, wird diskutiert. Rasterelektronenmikroskopische Untersuchungen bestätigten die morphologischen Merkmale, welche bereits für die Siphoniulida angegeben wurden: modifizierte Vorderbeine, scheinbar beinloser dritter Körperring, kleiner, zugespitzter Kopf, Antennen mit abgeflachten Borstenhaaren, fehlende Saftlöcher. Die männlichen Gonopoden werden hier zum ersten Male beschrieben: nur das vordere Beinpaar des 7. Ringes bildet die Gonopoden, das hintere Beinpaar desselben Ringes ist als normales Laufbeinpaar ausgebildet. Die Gonopoden sind stark modifizierte Strukturen. Das Gnathochilarium weicht deutlich von dem der Colobognathen ab, es besteht aus tastertragenden Stipites, langgestreckten Lingula Lamellae mit Tastern und einem zentralen, schmalen Sklerit, wahrscheinlich dem Mentum. Der Epiproct trägt vier Strukturen, die wahrscheinlich als Spinngriffel zu interpretieren sind. Trotz der Entdeckung von Männchen müssen die Siphoniulida weiterhin als Helminthomorpha incertae sedis angesehen werden. 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