Supraspinal Control of Unilateral Locomotor Performance: An FMRI Study Using a Custom Pedaling Device

This study aimed to develop a novel unilateral pedaling device, validate its function, and use it in an fMRI study of bilateral vs. unilateral locomotor control. The new device is MRI compatible and allows for conventional coupled bilateral pedaling, along with decoupled unilateral pedaling. It was designed with an assistance mechanism to simulate the presence of the non-contributing leg while pedaling unilaterally. During coupled bilateral pedaling, the two legs work in unison: while one leg is extending in the downstroke, it provides support to lift the other leg back up as it is flexing in the upstroke. The device uses an eccentric pulley to stretch elastic bands during the downstroke, storing energy that is released back during the upstroke to assist the leg as the bands relax. A phantom scan in the MRI machine was performed, which confirmed that the device did not interfere with signal detection. Experiments were performed to test the function of the device, showing that the assistance mechanism was able to adequately simulate the presence of the non-contributing leg during unilateral pedaling. The velocity and EMG profiles matched between unilateral and bilateral pedaling, with consistent results across days. An fMRI study was performed to compare brain activation associated with coupled bilateral, right unilateral, and left unilateral pedaling in able-bodied individuals with a healthy nervous system. Task related brain activity was seen in the primary sensorimotor cortex (M1S1), Brodmann’s area 6 (BA6), and the cerebellum (Cb). The laterality of activation was shifted to the contralateral M1S1 and ipsilateral Cb during unilateral pedaling, but some bilateral activation remained. BA6 showed no lateralization in activity. Additionally, there was no difference in the magnitudes of the laterality shift in right and left pedaling, and bilateral pedaling was not shifted to either hemisphere. Volume during unilateral pedaling showed no significant change in any brain area across conditions. These observations of laterality and volume suggest the existence of common regions of brain activation for bilateral and unilateral pedaling. Mean intensity in the common area of activation was lower in M1S1, BA6, and Cb for right and left unilateral compared to bilateral pedaling

An investigation of dynamic human muscle function using a variable inertial loading system

This thesis has developed and utilised an inertial loading system to study human skeletal muscle power output. Specifically, the apparatus has been used to study the effects of different modes of exercise, muscle myosin isoform composition and the effects of ageing on the ability of the lower limb muscles to generate explosive power. A variable inertial loading system was designed and constructed which allowed for the sensitive detection of the rotational properties of a flywheel from which the contractile characteristics of muscle could be inferred. When housed in the Nottingham Power Rig (NPR) the peak power generated by young non-trained male subjects from a single lower limb thrust ranged from 608 - 965 Watts and was found to occur at inertial loads ranging from 0.09 - 0.22 kgm2. To investigate the low power outputs observed at the low inertial loads, where the contraction time was short, a pre release mechanism was incorporated into the flywheel assembly. Significant increases in power output of ~ 17% were achieved at the lowest inertial load (P = 0.02), if a prior build up of isometric torque was allowed prior to movement. This suggested that at the low inertial loads, without the pre release, insufficient time was allowed for the muscle to generate its maximum power output. The flywheel system was incorporated into a cycle ergometer to allow power - velocity characteristics to be examined during inertial sprint cycling. Peak power obtained in young subjects (n = 9) was significantly higher in the cycle exercise when compared with the NPR (1620 vs. 937 Watts). In contrast to the NPR where a parabolic relationship between power and inertial load was observed, during sprint cycling power plateaued above a 'critical' load. It was concluded that the repetitive acceleration of inertial loads, above this critical threshold, will always allow the expression of peak power during cycling as ultimately a velocity will be achieved which corresponds to that required for peak power generation. An analysis of the myosin heavy chain (MHC) isoform composition of the vastus lateralis muscle was performed in young and elderly male subjects (n = 14, mean age 29.4 and 73.8). The percentage MHC-II isoform composition was significantly lower in the older subjects as was the velocity at which peak power occurred (Vopt). Overall the Vopt during sprint cycling was found to be related to the percentage MHC-II composition of the vastus lateralis (R = 0 .82, P<0.001). Finally, muscle power was examined in Elite level master Olympic weightlifters (n = 54, aged 40 - 87 years) and aged matched controls. On average the weightlifters generated ~ 32% more peak power than their aged matched counterparts and required significantly higher inertial loads to express their peak power output. In spite of 'load optimisation', power declined at twice the rate of strength. The levels of power suggest a 20 year advantage for the weightlifters

Robotics 2010

Without a doubt, robotics has made an incredible progress over the last decades. The vision of developing, designing and creating technical systems that help humans to achieve hard and complex tasks, has intelligently led to an incredible variety of solutions. There are barely technical fields that could exhibit more interdisciplinary interconnections like robotics. This fact is generated by highly complex challenges imposed by robotic systems, especially the requirement on intelligent and autonomous operation. This book tries to give an insight into the evolutionary process that takes place in robotics. It provides articles covering a wide range of this exciting area. The progress of technical challenges and concepts may illuminate the relationship between developments that seem to be completely different at first sight. The robotics remains an exciting scientific and engineering field. The community looks optimistically ahead and also looks forward for the future challenges and new development

Spacelab Science Results Study

Beginning with OSTA-1 in November 1981 and ending with Neurolab in March 1998, a total of 36 Shuttle missions carried various Spacelab components such as the Spacelab module, pallet, instrument pointing system, or mission peculiar experiment support structure. The experiments carried out during these flights included astrophysics, solar physics, plasma physics, atmospheric science, Earth observations, and a wide range of microgravity experiments in life sciences, biotechnology, materials science, and fluid physics which includes combustion and critical point phenomena. In all, some 764 experiments were conducted by investigators from the U.S., Europe, and Japan. The purpose of this Spacelab Science Results Study is to document the contributions made in each of the major research areas by giving a brief synopsis of the more significant experiments and an extensive list of the publications that were produced. We have also endeavored to show how these results impacted the existing body of knowledge, where they have spawned new fields, and if appropriate, where the knowledge they produced has been applied