Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Approved for public release; distribution is unlimited / "Human body motion tracking using inertial sensors requires an attitude estimation filter capable of tracking in all orientations. One way to represent orientation is to use Euler angles, but they have singularities and therefore are not suitable for human body tracking applications. Quaternions can be used to represent orientation without incurring singularities. A quaternion-based Kalman filter has been designed for this purpose and implemented in this thesis. Also, a new suboptimal algorithm to compute the quaternions based on magnetometer and accelerometer data is implemented. This new algorithm called "Factored Quaternion Algorithm" is computationally simpler than previous methods and provides a decoupling property from magnetometer and accelerometer data." p. i. / Lieutenant Junior Grade, Mexican Navy

Swimming is important to the ecology of many species of scallop but the effects of temperature upon swimming are not clear. The ecology and natural history of scallops is introduced followed by a description of the state of current knowledge of scallop swimming, muscle physiology and energetics. The effects of temperature and the mechanisms used by ectotherms to compensate for such changes over acute, seasonal and evolutionary timescales are discussed. Scallops are active molluscs, able to escape from predators using jet propelled swimming. Queen scallops (Aequipecten opercularis) were acclimated to 5,10 and 15°C in the laboratory and collected in Autumn (13±3°C) and Winter (8±2°C) in order to investigate seasonal acclimatisation. The first jetting cycle of escape responses in these animals was recorded using high-speed video (200-250fps). Whole-animal velocity and acceleration were determined while measurements of valve movement and jet area allowed the calculation of muscle shortening velocity, force and power output. Peak swimming speed was significantly higher at 15°C (0.37m.s⁻¹) than at 5°C (0.28m.s⁻¹). Peak acceleration was 77% higher at 15°C (7.88m.s⁻²) than at 5°C (4.44m.s⁻²). Mean cyclic power output was also higher at 15°C (31.3W.kg⁻¹) than at 5°C (23.3W.kg⁻¹). Seasonal comparison of swimming in freshly caught animals revealed significantly greater acceleration (x2 at 11°C) and velocity during jetting in Winter than in Autumn animals (ANCOVA). These were associated with significant increases in peak power output (x8 at 11 °C), force production and muscle shortening velocity. Actomyosin ATPase activity was significantly higher (31 % at 15°C) in winter animals with peptide mapping of the Myosin heavy chain showing no differences between groups. Increases in muscle power output were associated with reductions in the length of the jetting phase as a proportion of the overall cycle. As a result large changes in muscle performance resulted in large short-term whole body performance enhancement but little difference to velocity over the cycle. Measurements of the swimming performance of the Antarctic scallop were made from videos of escape responses. Animals were acclimated to +2 and -1 °C in the laboratory and compared to animals maintained at natural water temperature (0±0.5°C) at the time of experimentation. Adamussium was very sensitive to temperature change with the proportion of swimming responses being less common at higher temperatures and where an individual was exposed to temperatures above it's maintenance temperature. Analysis of the first jetting cycle of swimming was carried out as described in Chapter 2. These analyses revealed that over the small temperature range that the animals can tolerate swimming performance is strongly temperature dependent. Q₁₀s above 2 included those for thrust (3.74), mean cyclic swimming speed (2.46), mean cyclic power output (5.71) and mean muscle fibre shortening velocity (2.16). Adamussium did not demonstrate strong phenotypic plasticity with no significant differences in swimming of muscle performance between animals acclimated to different temperatures. Comparison of the relationship between swimming velocity and temperature in Adamussium and other species showed little evidence for evolutionary compensation for temperature with all data fitting to a single relationship with a Q₁₀ of 1.96 (0-20°C). Similar results were obtained for power output and the performance of in vitro muscle preparations. These results are discussed in the light of field studies revealing the low predator pressure and escape performance of wild Adamussium. In vivo ³¹P-Nuclear Magnetic Resonance Spectrometry (MRS) was used to measure the levels of ATP, Phospho-l-arginine (PLA) and inorganic phosphorous (PI) in the adductor muscle of the Antarctic scallop, Adamussium colbecki, and two temperate species, Aequipecten opercularis and Pecten maximus. Graded exercise regimes from light (1-2 contractions) to exhausting (failing to respond to further stimulation) were imposed upon animals of each species. MRS allowed non-invasive measurement of metabolite levels and intracellular pH at high time resolution (30-120s intervals) during exercise and throughout the prolonged recovery period. Significant differences were shown between the magnitude and form of the metabolic response with increasing levels of exercise. Short-term (first 15 minutes) muscle alkalosis was followed by acidosis of up to 0.2 pH units during the recovery process. Aequipecten had significantly higher resting muscle PLA levels than either Pecten or Adamussium, used a five-fold greater proportion of this store per contraction and was able to perform only half as many claps (maximum of 24) as the other species before exhaustion. All species regenerated their PLA store at a similar rate despite widely different environmental temperatures. The major results and their impact on our knowledge of biomechanics and it's temperature dependence are discussed. Suggestions for future research based upon the experimental findings and techniques developed are presented.

Our goal was to assess regional differences in denticle density and skin tensile properties in four coastal species of shark. We hypothesized that the denticle density, tensile strength (MPa), stiffness (MPa), and toughness of skin (MJ·m^-3) would vary regionally along the body of an individual and among species. An hourglass-shaped punch was used to extract the skin samples at 10 anatomical landmarks and denticle density was quantified. Denticle density varied significantly among both regions and species, and showed a significant species by region interaction. Skin samples were tested in tension at a strain rate of 2 mm-s until failure. We found significant species and region effects for all tensile and denticle density properties. Also, denticle density increases with skin stiffness but decreases with toughness. Shark skin toughness is similar to that of mammalian tendons. These data show shark skin functions as an exotendon, able to conserve energy during swimming. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Locomotion, including running, walking, and swimming, is a complex behavior enabling animals to interact with the environment. Vertebrate locomotion depends upon sets of interneurons in the spinal cord, known as the central pattern generator (CPG). The CPG performs multiple roles: pattern formation (left-right alternation and flexor-extensor alternation) and rhythm generation (the onset and frequency of locomotion). Many studies have begun to unravel the organization of the neuronal circuits underlying left-right and flexor-extensor alternation. However, despite pharmacologic, lesion, and optogenetic studies suggesting that the rhythm generating neurons are ispilaterally-projecting glutamatergic neurons, the precise cellular identification of rhythm generating neurons remains largely unknown. Traditionally, CPG networks (both pattern formation and rhythm generation) are thought to reside upstream of motor neurons, which serve as the output of the spinal cord. Recently however, it has been discovered that direct stimulation of lumbar motor neurons using the intact ex vivo neonate mouse spinal cord preparation can activate CPG networks to produce locomotor-like behavior. Furthermore, depressing motor neuron discharge decreases locomotor frequency, whereas increasing motor neuron discharge accelerates locomotor frequency, suggesting that motor neurons provide ongoing feedback to the CPG. However, the circuit mechanisms through which motor neurons can influence activity in the CPG in mammals remain unknown. Here, I used motor neurons as a means of accessing CPG interneurons by asking how motor neuron activation might induce locomotor-like activity. Through intracellular recording and morphological assays, I discovered that ventral spinocerebellar tract (VSCT) neurons are activated monosynaptically following motor neuron axon stimulation through chemical and electrical synapses. A subset of VSCT neurons were located close to or within the motor neuron nucleus. VSCT neurons were found to be excitatory, have descending spinal axon collaterals, and influence motor neuron output, suggesting that VSCT neurons are positioned advantageously to initiate and maintain locomotor-like rhythmogenesis. Intracellular recording from VSCT neurons revealed that they exhibit rhythmic activity during locomotor-like activity. VSCT neurons were found to contain the rhythmogenic pacemaker Ih current and to be connected to other VSCT neurons, at least through gap junctions. Optogenetic and chemogenetic manipulation of VSCT neuron activity provided evidence that VSCT neurons are both necessary and sufficient for the production of locomotor-like activity. Silencing VSCT neurons prevented the induction of such activity, whereas activation of VSCT neurons was capable of inducing locomotor-like activity. The production of locomotor-like activity by VSCT neuron photoactivation was dependent upon both electrical communication through gap junctions as well as the pacemaker Ih current. The evidence presented in this thesis suggests that VSCT neurons are critical components for rhythm generation in the mammalian CPG and are key mediators of locomotor activity.

Piezoelectric materials have been widely used in applications such as transducers, acoustic components, as well as motion and pressure sensors. Because of the material’s biocompatibility and flexibility, its applications in biomedical and biological systems have been of great scientific and engineering interest. In order to develop piezoelectric sensors that are small and functional, understanding of the material behavior is crucial. The major objective of this research is to develop a test system to evaluate the performance of a sensor made from polyvinylidene fluoride and its uses for studying insect locomotion and behaviors. A linear stage laboratory setup was designed and built to study the piezoelectric properties of a sensor during buckling deformation. The resulting signal was compared with the data obtained from sensors attached a cockroach, Blaberus discoidalis. Comparisons show that the buckling generated in laboratory settings can be used to mimic sensor deformations when attached to an insect. An analytical model was also developed to further analyze the test results. Initial analysis shows its potential usefulness in predicting the sensor charge output. Additional material surface characterization studies revealed relationships between microstructure properties and the piezoelectric response. This project shows feasibility of studying insects with the use of polyvinylidene fluoride sensors. The application of engineering materials to insect studies opens the door to innovative approaches to integrating biological, mechanical and electrical systems.

Primary spinal cord injury (SCI) results from direct mechanical damage to the spinal cord. The resulting pathochemical and pathophysiological events, including oxidative stress and inflammation, lead to secondary injury. The ability to decrease secondary injury may lead to improved recovery. Increasing glutathione production after SCI leads to decreased secondary injury. Glutamine is an important precursor to glutathione following trauma. Skeletal muscle phenotype is strongly influenced by neuromuscular activity. SCI causes myosin heavy chain (MyHC) profiles to shift towards faster isoforms in slow muscles and slower isoforms in fast muscles. The hypothesis was that glutamine, as a precursor of glutathione, administration to SCI rats would lead to better functional recovery and a more preserved MyHC phenotype in locomotory muscles. <p> Rats were assigned to one of four groups; healthy, laminectomy only, untreated SCI, and SCI treated with an intraperitoneal injection of 1mmol/kg glutamine every 12 hours for one week after injury. SCIs were performed at T6 with a modified aneurism clip. Functional recovery was measured weekly using the Basso-Beattie-Bresnahan scale and the angle board method. Six weeks later, all rats were killed, and their extensor digitorum longus and soleus muscles excised and weighed. MyHC composition of the muscles was determined using SDS-PAGE.<p>The hypothesis that glutamine treatment following SCI would lead to better functional recovery and a more preserved MyHC profile was validated. Glutamine treated rats received significantly higher BBB scores (p<0.01) and angle board scores (p<0.001) than untreated SCI rats. Glutamine treatment also reduces muscle atrophy in the soleus muscle, but not the extensor digitorum longus (EDL). In untreated rats the soleus muscle accounted for significantly (p<0.001) less of the percentage of total body weight than the soleus muscle from glutamine treated rats. Finally, SCI rats with preserved functional abilities displayed a significantly better preserved MyHC profile compared to untreated SCI rats. In the soleus healthy rats contain 94% type 1 myosin, treated rats maintained 68% which was significantly (p<0.001) greater than 28% maintained by untreated rats. In the EDL healthy rats contain 55% type 2b myosin, treated rats maintained 32% which was greater than 26% type 2b myosin maintained by untreated rats.

A variety of behavioural tests were used to examine both sensory and motor function of freely behaving unilaterally spinal cord-injured and uninjured rats. The first experiment was designed to determine whether sensory and motor differences existed between uninjured Fischer, Lewis, Long-Evans, Sprague-Dawley and Wistar rats using endpoint, quantitative kinematic, and kinetic measurements. The second experiment examined differences in sensorimotor responses to cervical spinal cord hemisection in Lewis, Long-Evans and Wistar rats. For the third experiment, reflex and locomotor abilities of unilateral cervical or thoracic spinal cord hemisected Long-Evans rats were determined using endpoint, semi-quantitative kinematic, and kinetic measurements. The fourth experiment was designed to investigate the importance of the rubrospinal tract and ascending dorsal column pathways to overground locomotion. This experiment was conducted to help explain the behavioural observations made following cervical spinal cord hemisection. Furthermore, this experiment examined the effects of combined unilateral rubrospinal and dorsal column injury on overground locomotion using endpoint and kinetic measurements. Finally, the fifth experiment set out to investigate the contribution of tracts running in the ventrolateral spinal cord on overground locomotion in freely behaving Long-Evans rats. These animals were assessed using endpoint and kinetic measurements. The results of these studies revealed that motor and sensory functions are not similar for all uninjured strains of rats. Specifically, Fischer rats tend to have considerable differences in their morphological features and sensorimotor abilities compared to the other strains examined. Results from the other experiments indicate that adult freely behaving female rats develop a characteristic gait when pathways important for locomotion are injured unilaterally, regardless of strain. The rubrospinal tract and ascending dorsal column pathways appear to be important for both skilled and flat-ground locomotion as well as forelimb use while rearing. Pathways traveling within the ventrolateral pathway, however, are not necessary or sufficient for locomotion or limb useage while rearing when injured by themselves. Animals with ventrolateral spinal funiculus injuries regain normal forelimb use and skilled locomotor abilities. Injury to the ventrolateral spinal funiculus, however, results in mild (compared to rubrospinal and dorsal column injured animals) yet long-lasting locomotor changes based on ground reaction force determination. These findings are in agreement with the current opinion that there is a substantial amount of functional redundancy of pathways traveling in the ventral and ventrolateral funiculi.

This thesis presents a model of legged locomotion in which position and velocity of body are directly controlled by positions and velocities of feet. One central relationship between foot acceleration, leg stroke and body velocity is developed. Procedures for determining all parameters of a step sequence including periods of constant body velocity (steady state) and constant linear acceleration of body (transient state) are presented. The following assumptions are used. Symmetrical trapezoidal velocity profiles are used for body and feet. Transient period is longer than or equal to one step time and a multiple of half step time. Step time and duty factor are constant during each locomotion stage. Stepping movements of a pair of legs are 180° out of phase and successive prints of one foot are symmetrically placed relative to the other foot. Starting and stopping occur with feet on a line perpendicular to the direction of body motion. Locomotion starts by lifting one foot and ends with one foot on the ground and the other being placed. When analyzing walking, designing a walking machine or designing a stepping sequence for an existing walking machine, it is important to understand constraints placed on body motion by motion of a single leg. Two dimensionless numbers which describe foot velocity profile are developed. Two additional dimensionless numbers result from constraint of leg workspace by foot acceleration and body velocity during steady state. These numbers provide useful relationships for design procedures. Defining a walking sequence requires transformation of objectives from global to body coordinates and continuously accounting for the relationship between these two systems. The technique described does this when body acceleration is non-zero as well as when body velocity is constant. Relationship between body and global coordinates is tracked for one leg pair using two diagrams: 1) position of feet relative to body versus time; 2) distances moved by feet and body in the global frame. A closed form inverse kinematic solution and an algorithm to find workspace for general three-revolute manipulator are presented. / Graduation date: 1991

A variety of behavioural tests were used to examine both sensory and motor function of freely behaving unilaterally spinal cord-injured and uninjured rats. The first experiment was designed to determine whether sensory and motor differences existed between uninjured Fischer, Lewis, Long-Evans, Sprague-Dawley and Wistar rats using endpoint, quantitative kinematic, and kinetic measurements. The second experiment examined differences in sensorimotor responses to cervical spinal cord hemisection in Lewis, Long-Evans and Wistar rats. For the third experiment, reflex and locomotor abilities of unilateral cervical or thoracic spinal cord hemisected Long-Evans rats were determined using endpoint, semi-quantitative kinematic, and kinetic measurements. The fourth experiment was designed to investigate the importance of the rubrospinal tract and ascending dorsal column pathways to overground locomotion. This experiment was conducted to help explain the behavioural observations made following cervical spinal cord hemisection. Furthermore, this experiment examined the effects of combined unilateral rubrospinal and dorsal column injury on overground locomotion using endpoint and kinetic measurements. Finally, the fifth experiment set out to investigate the contribution of tracts running in the ventrolateral spinal cord on overground locomotion in freely behaving Long-Evans rats. These animals were assessed using endpoint and kinetic measurements. The results of these studies revealed that motor and sensory functions are not similar for all uninjured strains of rats. Specifically, Fischer rats tend to have considerable differences in their morphological features and sensorimotor abilities compared to the other strains examined. Results from the other experiments indicate that adult freely behaving female rats develop a characteristic gait when pathways important for locomotion are injured unilaterally, regardless of strain. The rubrospinal tract and ascending dorsal column pathways appear to be important for both skilled and flat-ground locomotion as well as forelimb use while rearing. Pathways traveling within the ventrolateral pathway, however, are not necessary or sufficient for locomotion or limb useage while rearing when injured by themselves. Animals with ventrolateral spinal funiculus injuries regain normal forelimb use and skilled locomotor abilities. Injury to the ventrolateral spinal funiculus, however, results in mild (compared to rubrospinal and dorsal column injured animals) yet long-lasting locomotor changes based on ground reaction force determination. These findings are in agreement with the current opinion that there is a substantial amount of functional redundancy of pathways traveling in the ventral and ventrolateral funiculi.