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The effects of an aerobic walking program, from 22 to 30 wk gestation, on aerobic fitness, vitamin B-6 status, and birth outcome was studied in 28 healthy, pregnant women aged 21-36 yr receiving vitamin-mineral supplements. Aerobic fitness was assessed by heart rate (HR) and relative oxygen consumption (VO₂, ml/kg/min) during 2 submaximal treadmill walking tests (22 and 30 wk). HR responses were significantly lower for walking subjects (W; n=18) compared to nonwalking (NW; n=10) at 2 and 4 min and near significance at 6 min of the 30 wk treadmill test. HR increased significantly at 2 min for NW from 22 to 30 wk. Oxygen consumption significantly decreased for W from 22 to 30 wk at 2, 4, and 6 min of exercise but remained unchanged for NW. Mean vitamin B-6 intake, minus the 10 mg supplement, was at least two-thirds the 1980 Recommended Dietary Allowance. Values for plasma total vitamin B-6 assessed microbiologically were in the low-normal range for only 3 subjects (1 W at 22 wk and 2 W at 30 wk). Values for plasma pyridoxal phosphate levels assessed radioenzymatically were in the low-normal range for only 2 subjects (1 W at 22 wk and 1 W at 30 wk). Birth weight, Apgar scores, and labor duration were similar for both groups. Participation in a walking program by pregnant women taking vitamin-mineral supplements slightly improved aerobic fitness without affecting vitamin B-6 status (probably due to the supplement usage) or birth outcome. / M.S.

Bipedal robots offer a uniquely flexible platform capable of navigating complex, human-centric environments. This makes them ideally suited for a variety of missions, including disaster response and relief, emergency scenarios, or exoskeleton systems for individuals with disabilities. This, however, requires significant advances in humanoid locomotion and control, as they are still slow, unnatural, inefficient, and relatively unstable. The work of this dissertation the state of the art with the aim was of increasing the robustness and efficiency of these bipedal walking platforms. We present a series of control improvements to enable reliable, robust, natural bipedal locomotion that was validated on a variety of bipedal robots using both hardware and simulation experiments. A huge part of reliable walking involves maximizing the robot's control authority. We first present the development of a model predictive controller to both control the ground reaction forces and perform step adjustment for walking stabilization using a mixed-integer quadratic program. This represents the first model predictive controller to include step rotation in the optimization and leverage the capabilities of the time-varying divergent component of motion for navigating rough terrain. We also analyze the potential capabilities of model predictive controllers for the control of bipedal walking. As an alternative to standard trajectory optimization-based model predictive controls, we present several optimization-based control schemes that leverage more traditional bipedal walking control approaches by embedding a proportional feedback controller into a quadratic program. This controller is capable of combining multiple feedback mechanisms: ground reaction feedback (the "ankle strategy"), angular momentum (the "hip strategy"), swing foot speed up, and step adjustment. This allows the robot to effectively shift its weight, pitch its torso, and adjust its feet to retain balance, while considering environmental constraints, when available. To enable the robot to walk with straightened legs, we present a strategy that insures that the dynamic plans are kinematically and dynamically feasible to execute using straight legs. The effects of timing on dynamic plans are typically ignored, resulting in them potentially requiring significantly bending the legs during execution. This algorithm modifies the step timings to insure the plan can be executed without bending the legs beyond certain angle, while leaving the desired footsteps unmodified. To then achieve walking with straight legs we then presented a novel approach for indirectly controlling the center of mass height through the leg angles. This avoids complicated height planning techniques that are both computationally expensive and often not general enough to consider variable terrain by effectively biasing the solution of the whole-body controller towards using straighter legs. To incorporate the toe-off motion that is essential to both natural and straight leg walking, we also present a strategy for toe-off control that allows it to be an emergent behavior of the whole-body controller. The proposed approach was demonstrated through a series of simulation and experimental results on a variety of platforms. Model predictive control for step adjustment and rough terrain is illustrated in simulation, while the other step adjustment strategies and straight leg walking approaches are presented recovering from external disturbances and walking over a variety of terrains in hardware experiments. We discuss many of the practical considerations and limitations required when porting simulation-based controller development to hardware platforms. Using the presented approaches, we also demonstrated a important concept: using whole-body control frameworks, not every desired motion need be directly commanded. Many of these motions, such as toe-off, may simply be emergent behaviors that result by attempting to satisfy other objectives, such as desired reaction forces. We also showed that optimization is a very powerful tool for walking control, able to determine both stabilizing inputs and joint torques. / Ph. D. / Bipedal robots offer a uniquely flexible platform capable of navigating the complex, humancentric environment that we live in. This makes them ideally suited for a variety of missions, including disaster response and relief, emergency scenarios, or exoskeleton systems for individuals with disabilities. This, however, requires significant advances in humanoid locomotion and control, as they are still slow, unnatural, inefficient, and relatively unstable. The work of this dissertation aims to increase the robustness and efficiency of these bipedal walking platforms. To increase the overall stability of the robot while walking, we aimed to develop new control schemes that incorporate more of the same balance strategies used by people. These include the adjustment of ground reaction forces (the “ankle strategy”, shifting weight), angular momentum (the “hip strategy”, pitching the torso and windmilling the arms), swing foot speed up, and step adjustment. Using these approaches, the robot is able to walk much more stably. With the ability to use human-like control strategies, the next step is to develop appropriate methods to allow it to walk with straighter legs. Without correct step timing, it may be necessary at times to significantly bend the knees to take the specified step. We develop an approach to adjust the step timing to decrease the required knee bend of the robot. We then present an approach for indirectly controlling the robot height through the knee angles. This avoids traditional complicated height planning techniques that are both computationally hard and not general enough to consider complex terrain. To incorporate the toe-off motion that is essential to both natural and straight leg walking, we also present a new strategy for toe-off that allows it to emerge natural from the controller. We present the proposed approach through a series of simulation and experimental results on several robots and in several environments. We discuss many of the practical considerations and limitations required when porting simulation-based controller development to hardware platforms. Using the presented approaches, we also demonstrated an important concept: using whole-body control frameworks, not every desired motion need be directly commanded. Many of these motions, such as toe-off, may simply be emergent behaviors that result by attempting to satisfy other objectives, such as desired reaction forces. We also showed that optimization is a very powerful tool for walking control, able to determine both stabilizing inputs and joint torques.

Study design is among the most fundamental factors influencing collection and interpretation of data. The purpose of this study is to understand the effect of design choices by evaluating gait mechanics in healthy control participants using three primary objectives: 1) determine the repeatability of marker placement, 2) determine the effect of set versus self-selected walking speed, and 3) examine the correlation between gait asymmetry and motor variability. Ten and fifty-one healthy control participants were recruited for aim 1 and aims 2/3, respectively. Reflective markers were placed on lower-extremity bony landmarks and participants walked on an instrumented treadmill while 3D motion capture data was collected. For aim 1, this procedure was repeated at two time points 30 minutes apart. For aims 2 and 3, participants completed set and self-selected speed trials. JMP Pro 13 was used to compare joint kinetics and gait kinematics for all aims. Marker placement was repeatable between time points. Participants walked slower in the self-selected walking speed trial, which resulted in both kinematic and kinetic gait mechanics alterations. Gait asymmetry was significantly correlated with motor variability for both spatial and temporal measures. Current study findings reiterated the importance of walking speed when evaluating gait symmetry, joint kinetics, and kinematics. The decision regarding whether to utilize a set or self-selected speed condition within a study design should be made based on whether the measures of interest are independent of walking speed. Gait asymmetry and motor variability are related and should not be treated as independent components of gait. / Master of Science / This study aims to evaluate gait mechanics in healthy young adults by evaluating the impact of multiple study design choices and relationships between different aspects of gait (walking). Loading and movement walking data was collected from a total of sixty-one participants. This data was then used to calculate several measures of gait including symmetry between limbs, joint ranges of motion, and variability of movement. The potential impact of study design choices including setting walking speed for all participants and evaluating loading asymmetry and movement variability independently are discussed based on the findings of the current study.

Resuspended floor dust constitutes up to sixty percent of the total particulate matter in indoor air. This fraction may also include virus-laden particles that settle on the floor after being emitted by an infected individual. This research focuses on predicting the concentration of influenza A viruses in resuspended dust, generated by people walking in a room, at various heights above the floor. Using a sonic anemometer, we measured the velocity field from floor to ceiling at 10-cm intervals to estimate the magnitude of turbulence generated by walking. The resulting eddy diffusion coefficients varied between 0.06 m2 s-1 and 0.20 m2 s-1 and were maximal at ~0.75-1 m above the floor, approximately the height of the swinging hand. We used these coefficients in an atmospheric transport model to predict virus concentrations as a function of the carrier particle size and height in the room. Results indicate that the concentration of resuspended viruses at 1 m above the floor is about seven times the concentration at 2 m. Thus, shorter people may be exposed to higher concentrations of pathogens in resuspended dust indoors. This study illuminates the possibility that particle resuspension could be a mode of disease transmission. It also emphasizes the importance of considering resuspension of particulate matter when designing ventilation systems and flooring in hospitals and residences. / Master of Science

Working from Charland's (1987) description of constitutive rhetoric, this thesis is concerned what the popular zombie apocalypse television series The Walking Dead (TWD) has to say regarding survival behavior in a post-apocalyptic world. TWD's plot focuses primarily on the relationships between survivor characters situated among the crumbling remains of society and humanity. An attempt is made to show how TWD (1) establishes a common ideology among its characters, and therefore (2) constitutes its characters as a primary audience through an ideology of inhumanity by three narrative ideological effects. In doing so, the study aims to advance understanding of constitutive rhetoric in a temporal sense and also to emphasize that popular culture artifacts suggest viewers as secondary audiences and implied auditors tied to ideologies. The results of this analysis suggest the new order of a post-apocalyptic world binds survivors into a collective and transhistorical subject. These characters are tied to their past before the apocalypse and also become relatively relatable for viewers. / Master of Arts

This study examined individual differences in spatial memory performance in 12-month-old infants using brain electrical activity and walking experience. Greenough's experience-expectant and experience-dependent model of development was used to examine EEG power values among infants with different levels of walking experience (non-walkers, novice, experienced). In accordance with this model, a trend was shown for novice walkers to have higher EEG power values than both non-walkers and experienced walkers only in the central region. Walkers were also found to score higher on an object retrieval (OR) spatial memory task than non-walkers, with amount of walking experience being inconsequential. In addition, infants who scored higher on the OR spatial memory task showed a trend for higher EEG power values in medial frontal, central and parietal areas than infants scoring lower on the OR task. This was not the case for the manual search spatial memory task (AB). There was no interaction among spatial memory performance, walking experience and brain electrical activity. The utility of OR as a spatial memory task that requires the integration of relevant perceptual-motor integration is discussed. / Master of Science

Exoskeletons are wearable assistive devices made to be worn by users to enhance the function of the joint, reduce metabolic costs, and reduce required biological work. This thesis looks at several different types of knee exoskeletons and how they affect the user’s biomechanics and reduce the tibiofemoral force experienced by the user. Tibiofemoral forces are one of the joint contact forces experienced at the knee and are dependent on the level of activity from the surrounding muscles (DeMers et al., 2014). The knee is one of the largest joints in the human body, but is also prone to injury and degradation, with a global incidence of 203 per 10,000 people developing knee osteoarthritis (Cui et al., 2020). Everyone’s step-by-step biomechanics are going very slightly but summed together the muscle activity will be very similar (Ivanenko et al., 2004). This makes it easy to design an exoskeleton for the common man and make slight alterations as needed. Through this literature review, it will be shown that powered exoskeletons can be effective at reducing the tibiofemoral forces during a variety of conditions, and are best suited by targeting the knee extensor muscles.

Yes / Tranquil spaces can be found and made in the city and their promotion and use by residents and visitors is an important means of building resilience. Studies have shown that spaces that are rated by visitors as tranquil are more likely to produce higher levels of relaxation and less anxiety that should ultimately result in health and well-being benefits. Such spaces can therefore be classed as restorative environments. Tranquil spaces are characterized by a soundscape dominated by natural sounds and low levels of man-made noise. In addition, the presence of vegetation and wild life has been shown to be an important contributory factor. Levels of rated tranquillity can be reliably predicted using a previously developed model TRAPT and then used to design and identify tranquil spaces, improve existing green spaces and develop Tranquillity Trails to encourage usage. Tranquillity Trails are walking routes that have been designed to enable residents and visitors to reflect and recover from stress while receiving the benefits of healthy exercise. This paper describes Tranquillity Trails designed for three contrasting areas. Predictions of the rated tranquillity have been made along these routes and feedback from users was elicited at one site that confirmed the expected benefits. / Bradford Centre for Sustainable Environments in the Faculty of Engineering and Informatics at the University of Bradford.