314 research outputs found
Muskuläre Biomechanik in der Sprunggelenkprothetik
Zusammenfassung: Das Ziel dieser orthopädisch-biomechanischen Studie war die Evaluation der Muskelfunktion von Patienten, bei welchen infolge unilateraler, schwerer Arthrose am oberen Sprunggelenk (OSG) eine Prothese eingesetzt wurde. Bei 10Patienten wurde vor und 1Jahr nach Implantation einer OSG-Prothese eine orthopädische und biomechanische Untersuchung durchgeführt. Dabei wurden der Schmerzscore, der "American Orthopaedic Foot and Ankle Society"- (AOFAS-)Ankle-Score, der Bewegungsumfang (ROM) des Sprunggelenks und der Unterschied zwischen dem Umfang des Unterschenkels des betroffenen und des kontralateralen gesunden Beins gemessen. Die biomechanische Beurteilung bestand aus einer simultanen Messung des maximal willkürlichen, isometrischen Drehmoments bei Plantarflexion und Dorsalextension des OSG sowie aus einem Oberflächenelektromyogramm (EMG; mittlere Frequenz und Intensität) von 4 Unterschenkelmuskeln: Tibialis anterior (TA), Gastrocnemius medialis (GM), Soleus (SO) und Peroneus longus (PL). Im Vergleich zur präoperativen Evaluation verbesserten sich der Schmerzscore von 6,7 auf 0,8Punkte, der AOFAS-Ankle-Score von 35,6 auf 92,3Punkte und der ROM nach Implantation der OSG-Prothese signifikant. Die mittlere Differenz des Unterschenkelumfangs zwischen den beiden Beinen nahm von 2,2cm auf 1,4cm ab. Dies war jedoch nicht signifikant. Das mittlere Drehmoment des betroffenen Sprunggelenks bei Dorsalextension stieg von 17,0 auf 25,8Nm und bei Plantarflexion von 15,7 auf 24,6Nm signifikant an. Bei der 1-Jahres-Nachkontrolle war die mittlere EMG-Frequenz in allen atrophischen Muskeln tiefer als bei den gesunden Muskeln der kontralateralen Seite. Ein Unterschied der mittleren EMG-Intensität zur kontralateralen gesunden Seite konnte nicht verifiziert werden. Daraus kann gefolgert werden, dass Patienten mit symptomatischer OSG-Arthrose mit einer Prothese eine bessere Funktion erlangen; 1Jahr nach der Operation entspricht dies jedoch nicht dem Ausmaß derjenigen des kontralateralen gesunden Bein
Analyse der Veränderungen von Wavelet-transformierten elektromyographischen Signalen, wie sie beim Tragen einer Kniebandage entstehen
Der Vergleich von diversen Elektromyogrammen stellt eine wesentliche Anforderung an die Datenanalyse dar. Das Ziel der vorliegenden Arbeit ist es, eine Methode mit geringem mathematischem Aufwand vorzustellen, mit der kleine Veränderungen am Bewegungsapparat durch Auswertung des EMG-Signals einfach und mit einer hohen Sensitivität ermittelt und dargestellt werden können. Die Wavelettransformierten Elektromyogramme bilden Intensitätsbilder, die in einem Bildraum als Punkte dargestellt werden können. Die Distanz-analyse der Bildpunkte im Bildraum erlaubt es festzustellen, ob zwei Gruppen von Elektromyogrammen - im vorliegenden Falle diejenigen, die beim Gehen mit und ohne Kniebandage gemessen wurden - sich im Mittel signifikant unterscheiden. Die Methode definiert eine Distanz-Winkel-Darstellung und Differenz-Intensitätsbilder, die es erlauben, die Auftrennung optisch zu beurteilen. Es ist zu erwarten, daβ bei gröβeren Interventionen die Unterschiede deutlicher erscheinen werden. The comparison of electromyograms represents a challenge for data analysis. The aim of the project was to present a method that uses a minimal computational effort to resolve small but significant changes in the muscular activity that occur while walking with and without a knee brace. The wavelet transformed electromyograms were represented as intensity patterns that resolve the power of the signal in time and frequency. The intensity pattern of each electromyogram defines single points in a pattern space. The distance between these points in pattern space were used to detect and show the separation between the groups of electromyograms that were recorded while walking with and without a knee brace. The method proposes a distance versus angle representation to visually discriminate the intensity patterns. Once it has been shown that the differences are statistically significant, one can visualize the result in a difference intensity pattern that indicates at what time and at what frequency the electromyograms vary between the two conditions tested. It is to be expected that interventions that are more intrusive than a knee brace will reveal even more distinct difference
A generalization of the van-der-Pol oscillator underlies active signal amplification in Drosophila hearing
The antennal hearing organs of the fruit fly Drosophila melanogaster boost their sensitivity by an active mechanical process that, analogous to the cochlear amplifier of vertebrates, resides in the motility of mechanosensory cells. This process nonlinearly improves the sensitivity of hearing and occasionally gives rise to self-sustained oscillations in the absence of sound. Time series analysis of self-sustained oscillations now unveils that the underlying dynamical system is well described by a generalization of the van-der-Pol oscillator. From the dynamic equations, the underlying amplification dynamics can explicitly be derived. According to the model, oscillations emerge from a combination of negative damping, which reflects active amplification, and a nonlinear restoring force that dictates the amplitude of the oscillations. Hence, active amplification in fly hearing seems to rely on the negative damping mechanism initially proposed for the cochlear amplifier of vertebrate
Two Phases for Compact U(1) Pure Gauge Theory in Three Dimensions
We show that if actions more general than the usual simple plaquette action
() are considered, then compact {\sl pure} gauge
theory in three Euclidean dimensions can have two phases. Both phases are
confining phases, however in one phase the monopole condensate spontaneously
`magnetizes'. For a certain range of parameters the phase transition is
continuous, allowing the definition of a strong coupling continuum limit. We
note that these observations have relevance to the `fictitious' gauge field
theories of strongly correlated electron systems, such as those describing
high- superconductors.Comment: 10 pages, Plain TeX, uses harvma
Drosophila TRPN( = NOMPC) Channel Localizes to the Distal End of Mechanosensory Cilia
BACKGROUND: A TRPN channel protein is essential for sensory transduction in insect mechanosensory neurons and in vertebrate hair cells. The Drosophila TRPN homolog, NOMPC, is required to generate mechanoreceptor potentials and currents in tactile bristles. NOMPC is also required, together with a TRPV channel, for transduction by chordotonal neurons of the fly's antennal ear, but the TRPN or TRPV channels have distinct roles in transduction and in regulating active antennal mechanics. The evidence suggests that NOMPC is a primary mechanotransducer channel, but its subcellular location-key for understanding its exact role in transduction-has not yet been established. METHODOLOGY/PRINCIPAL FINDINGS: Here, by immunostaining, we locate NOMPC at the tips of mechanosensory cilia in both external and chordotonal sensory neurons, as predicted for a mechanotransducer channel. In chordotonal neurons, the TRPN and TRPV channels are respectively segregated into distal and proximal ciliary zones. This zonal separation is demarcated by and requires the ciliary dilation, an intraciliary assembly of intraflagellar transport (IFT) proteins. CONCLUSIONS: Our results provide a strong evidence for NOMPC as a primary transduction channel in Drosophila mechansensory organs. The data also reveals a structural basis for the model of auditory chordotonal transduction in which the TRPN and TRPV channels play sequential roles in generating and amplifying the receptor potential, but have opposing roles in regulating active ciliary motility
A lattice study of 3D compact QED at finite temperature
We study the deconfinement phase transition and monopole properties in the
finite temperature 3D compact Abelian gauge model on the lattice. We predict
the critical coupling as function of the lattice size in a simplified model to
describe monopole binding. We demonstrate numerically that the monopoles are
sensitive to the transition. In the deconfinement phase the monopoles appear in
the form of a dilute gas of magnetic dipoles. In the confinement phase both
monopole density and string tension differ from semiclassical estimates if
monopole binding is neglected. However, the analysis of the monopole clusters
shows that the relation between the string tension and the density of monopoles
in charged clusters is in reasonable agreement with those predictions. We study
the cluster structure of the vacuum in both phases of the model.Comment: 18 pages, 14 EPS figures, LaTeX uses epsfig.st
Direct gating and mechanical integrity of Drosophila auditory transducers require TRPN1
The elusive transduction channels for hearing are directly gated mechanically by the pull of gating springs. We found that the transient receptor potential (TRP) channel TRPN1 (NOMPC) is essential for this direct gating of Drosophila auditory transduction channels and that the channel-spring complex was disrupted if TRPN1 was lost. Our results identify TRPN1 as a mechanical constituent of the fly's auditory transduction complex that may act as the channel and/or gating spring
Monopoles, confinement and deconfinement of (2+1)D compact lattice QED in external fields
The compact Abelian model in three space--time dimensions is studied in the
presence of external electromagnetic fields at finite temperatures. We show
that the deconfinement phase transition is independent on the strength of the
external fields. This result is in agreement with our observation that the
external fields create small--size magnetic dipoles from the vacuum which do
not influence the confining properties of the model. Contrary to the
deconfinement phase, the internal field in the direction of the applied
external field is attenuated in the confinement phase, this screening becomes
stronger with decreasing temperature.Comment: 22 pages, 24 EPS figures, LaTeX uses epsfig.st
A doublecortin containing microtubule-associated protein is implicated in mechanotransduction in Drosophila sensory cilia
Mechanoreceptors are sensory cells that transduce mechanical stimuli into electrical signals and mediate the perception of sound, touch and acceleration. Ciliated mechanoreceptors possess an elaborate microtubule cytoskeleton that facilitates the coupling of external forces to the transduction apparatus. In a screen for genes preferentially expressed in Drosophila campaniform mechanoreceptors, we identified DCX-EMAP, a unique member of the EMAP family (echinoderm–microtubule-associated proteins) that contains two doublecortin domains. DCX-EMAP localizes to the tubular body in campaniform receptors and to the ciliary dilation in chordotonal mechanoreceptors in Johnston's organ, the fly's auditory organ. Adult flies carrying a piggyBac insertion in the DCX-EMAP gene are uncoordinated and deaf and display loss of mechanosensory transduction and amplification. Electron microscopy of mutant sensilla reveals loss of electron-dense materials within the microtubule cytoskeleton in the tubular body and ciliary dilation. Our results establish a catalogue of candidate genes for Drosophila mechanosensation and show that one candidate, DCX-EMAP, is likely to be required for mechanosensory transduction and amplification
THE UTILISATION OF VALUE BASED MANAGEMENT IN THE STRATEGIC MANAGEMENT OF GERMAN’S AUTOMOTIVE INDUSTRY
The purpose of this research paper is to analyse the value-based management commitment of automotive enterprises and to examine the factors that explain the control parameters in automotive industry. There have been a few empirical studies published in the German’s automotive sector but most of the existing studies failed to provide evidence of utilisation of value-based management in the strategic management in the automotive sector. The German automotive industry’s development is closely related to global economic developments. Previous research work has considered control parameters of enterprises but there is little evidence on the factors that explain which control parameters are used in automotive industry. A survey based on annual reports from the year 2008 to 2011 is used. In total, 20 annual reports of automotive companies were analysed. The results show that automotive companies, especially Original Equipment Manufacturers (OEMs) and listed suppliers, have committed to value-oriented management and have implemented value-oriented approaches. However, not all of the suppliers are communicating this in their reports. The results also show that Economic Value Added (EVA) is the leading key indicator in the automotive industry
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