Infants born extremely prematurely (ie. &lt29 weeks gestation) or with extremely low birth weight (ie. &lt1000 grams) are at high-risk of major and minor motor sequelae that persist into the school years. Most of the research on the outcome of these high-risk infants has concentrated on the prevalence of major disability. The majority of high-risk children at school age have normal intelligence and no sensorineural disability. Despite this, these ???apparently normal??? high-risk children have a higher incidence of minor morbidities. Motor coordination problems are frequently reported, yet further investigation into the emergence of minor motor dysfunction, or its impact on academic achievement and everyday activities is seldom explored. The aim of this thesis was to provide a comprehensive investigation into motor dysfunction, which is commonly found in ???apparently normal??? high-risk children. This was addressed in a series of five studies that intended to provide insight into the emergence, prevalence, nature, and prediction of motor dysfunction in otherwise ???normal??? high-risk children. Study 1 examined the development of gross and fine motor skills from infancy to school age using a longitudinal cohort study design. ???Apparently normal??? high-risk children (n=58) were assessed with the Peabody Developmental Motor Scales at 18 months corrected age, 3 and 5 years. A significant proportion continued to have fine motor deficits to school age (64%), reflecting a persistent problem with fine motor skills throughout this period. The proportion of infants with gross motor deficits significantly increased from 18 months to 5 years (81.1%), particularly for the ???micropreemies???. Whilst there was no gender difference found, the development of gross and fine motor skills appeared to be influenced differently by the home environment. Study 2 examined the impact of motor dysfunction on performance at school age. The prevalence of Developmental Coordination Disorder (DCD) in ???apparently normal??? high-risk children was determined using a controlled cohort study design. In addition, the nature of DCD in this population was explored by testing sensorimotor abilities that possibly underlie the motor dysfunction. Fifty (50) high-risk children with IQ&lt85 and no identified sensorineural disability were assessed at 8 years of age along with a matched control from their respective class at school. The Movement Assessment Battery for Children and a battery of sensorimotor tests were administered. Results indicated a significantly higher prevalence of DCD (42%) in the high-risk group in comparison to the control group (8%). In relation to sensorimotor abilities that may influence motor performance, the high-risk group scored significantly lower on most of tests, however it was neurological ???soft signs???, postural praxis, and sequencing praxis that contributed to DCD in the high-risk group. Study 3 was designed to investigate the impact of motor dysfunction on a motor-based task performed within the school setting. Specifically, this study described handwriting skills in ???apparently normal??? high-risk children, determined the prevalence of handwriting dysfunction, and investigated sensorimotor abilities that may be associated with problematic handwriting. The high-risk cohort and matched controls described in study 2 were also administered a number of handwriting tests. High-risk children were found to have poorer handwriting legibility and speed in comparison to their classmates. The prevalence of handwriting dysfunction in the high-risk group was 46%, significantly higher than controls (18%). Hand preference, pencil grasp used, and pain whilst writing were comparable to the control group. The contribution of underlying sensorimotor abilities to handwriting dysfunction in the high-risk population however was not evident. By using the same subjects in studies 2 and 3, the co-morbidity of handwriting dysfunction with DCD could be determined. Of those high-risk children identified with DCD, 43% had co-morbid handwriting dysfunction. Study 4 explored the relationship between perinatal and environmental variables to Developmental Coordination Disorder and handwriting dysfunction in high-risk children. Perinatal and environmental variables of the 50 ???apparently normal??? high-risk children that participated in the previous study were analysed. Results indicated prolonged rupture of membranes (PROM) and retinopathy of prematurity (ROP) were significantly and independently associated with DCD, perhaps reflecting the impact of the antenatal infection process and visual development related to ROP on motor outcome in high-risk children. Perinatal variables were not associated with handwriting dysfunction, but high-risk males were more likely to have handwriting dysfunction. Maternal education and paternal occupation were associated with aspects of handwriting. Whilst handwriting is a motor-based activity, it appears to be influenced by environmental variables, similar to other academic areas for the high-risk population. Study 5 sought to determine whether a motor assessment at an earlier age could predict DCD in the ???apparently normal??? high-risk population at school age. Motor assessment at 12 months, 3 and 5 years for the high-risk subjects who participated in study 2 were analysed using Receiver Operator Curves (ROC curves). The 3 year assessment with the Peabody Developmental Motor Scales was the best predictor of DCD at 8 years, with the Griffiths Locomotor Scale at 3 years yielding a similar result. Findings suggest that high-risk children who scored below the specified cut-off points on 3 year motor assessments and who had a history of PROM or ROP were at greater risk of having motor-based problems that had the potential to interfere with functioning at school.

The control of skeletal muscle relies on a complex integration between descending central input and information that originates from receptors that lie within peripheral tissue. The following investigations were performed to contribute to our understanding of this control. Study 1 ( Chapter 2 ) was designed to determine ( using the H - reflex ) if muscle spindle feedback is similar in the gastrocnemius and soleus. The strength of the H - reflex at rest and during contraction was compared between muscles. The results showed that the maximal H - reflex obtained at any level of contraction is larger in the soleus than in the gastrocnemius. We argue that along with the muscles having different structures and functions, the recruitment capabilities of their motoneurons are quite different. We also found that the maximal M - wave, which has for years been thought to be a consistent measure of maximal muscle activity, was quite variable within subjects during different conditions. Review of the maximal M - wave literature showed evidence that variability in this response did exist between conditions, but that the variability was rarely seen in pooled data, and was therefore not often reported. Study 2 ( Chapter 3 ) was developed to determine if experimental recording techniques, or analysis methods, could affect the magnitude of the maximal M - wave within subjects. The first finding of this study showed that the two most commonly used analysis methods ( peak - to - peak amplitude and area ) provided comparable results, and could not account for the differences seen in the maximal M - wave magnitude. The study did however suggest that the orientation of surface recording electrodes can significantly alter the recorded signal. We argue that although bipolar surface recording is considered superior to monopolar recording in its ability to record a clean signal, it has a large limiting factor, which we call " signal cancellation ". The third study ( Chapter 4 ) focused on the variability in M - wave strength in the gastrocnemius and soleus during a variety of ankle orientations and voluntary contraction levels. This study supported our previous work, and showed that when monopolar recording is used, consistent and significant differences exist in the strength on the M - wave obtained during different conditions that were not seen in bipolar recordings. It was concluded that the difference in maximal M - wave strength obtained during different muscle conditions may be related to a change in the recording electrode to muscle bulk relationship. This finding is important as M - wave strength is consistently used as a normalisation factor in reflex studies, and therefore variability in this measure may seriously affect the results obtained during muscle reflex investigations. The final study ( chapter 5 ) considered the size of the H - reflex, the level of background muscle activity, and the subjects ' weight distribution, during painful and non - painful conditions. We determined that these factors were not modified by pain induced in either agonist or antagonist muscles. The final chapter outlines the major findings from this work, highlights limitations to the research conducted using the H - reflex, and makes suggestions for future research in this area. / Thesis (Ph.D.)--School of Molecular and Biomedical Science, 2006.

Graduation date: 2005

A method to design foot trajectory in Cartesian coordinates for a six-leg walking machine is presented in this thesis. The walking machine is based on the geometry of the darkling beetle. The walking procedure developed by Y.S. Baek is introduced first to provide step length and leg swing time for foot trajectory planning. This procedure also supplies required parameters to describe the relationship between feet and body during locomotion. The trajectory of a single foot consists of the path and its temporal attributes, that is, velocity and acceleration. Several methods and constraints for path and velocity profile design are discussed. Software developed in Microsoft Quick C is used to generate and animate on the screen a single desired foot trajectory applied to each of the six legs by combining paths and velocity profiles. The generated trajectory is converted to joint coordinates to provide necessary data for leg control. Since a single foot trajectory is applied to three pairs of legs of different design, three sets of joint coordinate sequences are produced. Furthermore, each leg consists of three segments and three joints necessitating nine control sequences altogether. Half-ellipse and trochoidal paths are interpolated with 5th and 6th order polynomials to determine minimum required joint acceleration. All paths and their first and second derivatives are required to be smooth. The effect of body pitch are also examined. / Graduation date: 1995

Thesis (Ph. D.)--University of California, San Diego, 1981. / Vita. Includes bibliographical references (leaves 127-130).

Thesis (Ph. D.)--University of California, San Diego, 1981. / Vita. Includes bibliographical references (leaves 127-130).

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains x, 54 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 49-51).

Transportvorgänge in und von Zellen sind von herausragender Bedeutung für das Überleben des Organismus. Muskeln müssen sich kontrahieren können, Chromosomen während der Mitose an entgegengesetzte Enden der Zelle bewegt und Organellen, das sind von Membranen umschlossene Kompartimente, entlang molekularer Schienen transportiert werden. <br /> Molekulare Motoren sind Proteine, deren Hauptaufgabe es ist, andere Moleküle zu bewegen. Dazu wandeln sie die bei der ATP-Hydrolyse freiwerdende chemische Energie in mechanische Arbeit um. Die Motoren des Zellskeletts gehören zu den drei Superfamilien Myosin, Kinesin und Dynein. Ihre Schienen sind Filamente des Zellskeletts, Actin und die Microtubuli. <br /> In dieser Arbeit werden stochastische Modelle untersucht, welche dazu dienen, die Fortbewegung dieser linearen molekularen Motoren zu beschreiben. Die Skala, auf der wir die Bewegung betrachten, reicht von einzelnen Schritten eines Motorproteins bis in den Bereich der gerichteten Bewegung entlang eines Filaments. Ein Einzelschritt überbrückt je nach Protein etwa 10 nm und wird in ungefähr 10 ms zurückgelegt. Unsere Modelle umfassen M Zustände oder Konformationen, die der Motor annehmen kann, während er sich entlang einer eindimensionalen Schiene bewegt. An K Orten dieser Schiene sind Übergänge zwischen den Zuständen möglich. Die Geschwindigkeit des Proteins lässt sich in Abhängigkeit von den vertikalen Übergangsraten zwischen den einzelnen Zuständen analytisch bestimmen. Wir berechnen diese Geschwindigkeit für Systeme mit bis zu vier Zuständen und Orten und können weiterhin eine Reihe von Regeln ableiten, die uns einschätzen helfen, wie sich ein beliebiges vorgegebenes System verhalten wird. <br /> Darüber hinaus betrachten wir entkoppelte Subsysteme, also einen oder mehrere Zustände, die keine Verbindung zum übrigen System haben. Mit einer bestimmten Wahrscheinlichkeit kann ein Motor einen Zyklus von Konformationen durchlaufen, mit einer anderen Wahrscheinlichkeit einen davon unabhängigen anderen. <br /> Aktive Elemente werden in realen Transportvorgängen durch Motorproteine nicht auf die Übergänge zwischen den Zuständen beschränkt sein. In verzerrten Netzwerken oder ausgehend von der diskreten Mastergleichung des Systems können auch horizontale Raten spezifiziert werden und müssen weiterhin nicht mehr die Bedingungen der detaillierten Balance erfüllen. Damit ergeben sich eindeutige, komplette Pfade durch das jeweilige Netzwerk und Regeln für die Abhängigkeit des Gesamtstroms von allen Raten des Systems. Außerdem betrachten wir die zeitliche Entwicklung für vorgegebene Anfangsverteilungen. <br /> Bei Enzymreaktionen gibt es die Idee des Hauptpfades, dem diese bevorzugt folgen. Wir bestimmen optimale Pfade und den maximalen Fluss durch vorgegebene Netzwerke. <br /> Um darüber hinaus die Geschwindigkeit des Motors in Abhängigkeit von seinem Treibstoff ATP angeben zu können, betrachten wir mögliche Reaktionskinetiken, die den Zusammenhang zwischen den unbalancierten Übergangsraten und der ATP-Konzentration bestimmen. Je nach Typ der Reaktionskinetik und Anzahl unbalancierter Raten ergeben sich qualitativ unterschiedliche Verläufe der Geschwindigkeitskurven in Abhängigkeit von der ATP-Konzentration. <br /> Die molekularen Wechselwirkungspotentiale, die der Motor entlang seiner Schiene erfährt, sind unbekannt.Wir vergleichen unterschiedliche einfache Potentiale und die Auswirkungen auf die Transportkoeffizienten, die sich durch die Lokalisation der vertikalen Übergänge im Netzwerkmodell im Vergleich zu anderen Ansätzen ergeben. / Transport processes in and of cells are of major importance for the survival of the organism. Muscles have to be able to contract, chromosomes have to be moved to opposing ends of the cell during mitosis, and organelles, which are compartments enclosed by membranes, have to be transported along molecular tracks.<br /> Molecular motors are proteins whose main task is moving other molecules.For that purpose they transform the chemical energy released in the hydrolysis of ATP into mechanical work. The motors of the cytoskeleton belong to the three super families myosin, kinesin and dynein. Their tracks are filaments of the cytoskeleton, namely actin and the microtubuli. <br /> Here, we examine stochastic models which are used for describing the movements of these linear molecular motors. The scale of the movements comprises the regime of single steps of a motor protein up to the directed walk along a filament. A single step bridges around 10 nm, depending on the protein, and takes about 10 ms, if there is enough ATP available. Our models comprise M states or conformations the motor can attain during its movement along a one-dimensional track. At K locations along the track transitions between the states are possible. The velocity of the protein depending on the transition rates between the single states can be determined analytically. We calculate this velocity for systems of up to four states and locations and are able to derive a number of rules which are helpful in estimating the behaviour of an arbitrary given system.<br /> Beyond that we have a look at decoupled subsystems, i.e., one or a couple of states which have no connection to the remaining system. With a certain probability a motor undergoes a cycle of conformational changes, with another probability an independent other cycle. <br /> Active elements in real transport processes by molecular motors will not be limited to the transitions between the states. In distorted networks or starting from the discrete Master equation of the system, it is possible to specify horizontal rates, too, which furthermore no longer have to fulfill the conditions of detailed balance. Doing so, we obtain unique, complete paths through the respective network and rules for the dependence of the total current on all the rates of the system. Besides, we view the time evolutions for given initial distributions. <br /> In enzymatic reactions there is the idea of a main pathway these reactions follow preferably. We determine optimal paths and the maximal flow for given networks. <br /> In order to specify the dependence of the motor's velocity on its fuel ATP, we have a look at possible reaction kinetics determining the connection between unbalanced transitions rates and ATP-concentration. Depending on the type of reaction kinetics and the number of unbalanced rates, we obtain qualitatively different curves connecting the velocity to the ATP-concentration. <br /> The molecular interaction potentials the motor experiences on its way along its track are unknown. We compare different simple potentials and the effects the localization of the vertical rates in the network model has on the transport coefficients in comparison to other models.

This thesis deals with the integral motor of tomorrow, and particularly with a variable speed, sensorless permanent magnet synchronous motor with an integrated converter. The rated power is 15 kW at 1500 r/min. The outer dimensions are approximately the same as for the equivalent standard induction motor. Control strategies for pumps and fans, i.e. suitable loads for variable speed motors, are briefly described. The huge energy savings that can be made by reducing the speed instead of throttling/choking the flow are pointed out. Compared to installing an induction motor with a separate converter, a PM integral motor will probably pay-off in less than a year. A totally analytical expression for calculating the airgap flux density of permanent magnet motors with buried magnets is derived. The analytical expression includes axial leakage, and iron saturation of the most narrow part of the magnetic circuit of the machine. A computer program for optimization of PM motors with buried magnets has been developed. It was used to design the manufactured prototype PM integral motor, and the parameters are investigated with analytical and/or FEM calculations. The optimization program is also used to suggest nearoptimum pole numbers for desired powers (4-37 kW) and speeds (750- 3000 r/min) of inverter-fed PM motors. Results show that compact buried PM motors should have relatively large airgaps and high NdFeB-magnet masses to improve the efficiency. Ferrite magnets are unsuitable. Measurements on the manufactured PM motor, the novel concept of stator integrated filter coils, and the complete PM integral motor are presented. Special attention was given to temperature and overall efficiency measurements. The rotor cage losses were investigated by time-stepping FEM. Four short circuit fault conditions were also examined in order to evaluate the risks of demagnetization of the buried magnets.