Developing Continuous Predictive Controls for Ankle Angle and Moment Across Multiple Mobility Tasks

This thesis aimed to create a predictive model for controlling lower limb prostheses, using electrical activity from muscles in the residual limb to predict ankle angle and moment across mobility tasks including level ground walking, stair ascent, and descent (LW, SA, and SD). In aim 1, kinematic and kinetic ankle data, were used together with electromyographic (EMG) signals obtained from six healthy ambulators to train a nonlinear autoregressive (NARX) model to predict ankle angle and moment. Networks were trained with a delay of 58.33 ms, using a 120 ms sampling window and tested for their ability to predict ankle angle and moment across mobility tasks using a 10-fold cross validation. The average root-mean-squared error (RMSE) of networks across tasks was 2.93°±0.70° and 0.12±0.03 Nm/Kg when shank velocity was provided as input, 4.92◦±1.39° and 0.15±0.04 Nm/Kg when EMG activity was provided as input, and 2.37°±0.58° and 0.084±0.026 Nm/Kg when inputs were combined. In Aim 2, the best performing networks were tested in a modified version of a model of the Marquette powered prosthetic foot. Three cases were considered: open-loop NARX prediction with internal feedback and closed-loop NARX prediction that used either ankle angle feedback, or ankle angle and moment feedback from the prosthetic model. The internal feedback model accurately predicted its target without incorporating information from prosthetic foot performance. Simulations that incorporated modelled moment feedback increased error, causing instability over time in some SA and SD trials from a mismatch in desired and achieved ankle moment. The NARX networks in Aim 1 accurately predicted ankle angle and moment across subjects and mobility tasks and could be used to provide kinematic/kinetic control input for a powered prosthesis. In Aim 2, the subsequent control simulation performed well with internal feedback, but full closed-loop validation requires an updated model that incorporates loading and ground reaction forces. The system\u27s potential for real-time operation without conscious input is promising. Future work should explore human-in-the-loop control performance and testing with amputee data, to characterize the impact of individual sources of variability associated with changes in residual muscle signals, adaptation over time, and diverse movement patterns

Neurological Disease Rises from Ocean to Bring Model for Human Epilepsy to Life

Domoic acid of macroalgal origin was used for traditional and medicinal purposes in Japan and largely forgotten until its rediscovery in diatoms that poisoned 107 people after consumption of contaminated mussels. The more severely poisoned victims had seizures and/or amnesia and four died; however, one survivor unexpectedly developed temporal lobe epilepsy (TLE) a year after the event. Nearly a decade later, several thousand sea lions have stranded on California beaches with neurological symptoms. Analysis of the animals stranded over an eight year period indicated five clusters of acute neurological poisoning; however, nearly a quarter have stranded individually outside these events with clinical signs of a chronic neurological syndrome similar to TLE. These poisonings are not limited to sea lions, which serve as readily observed sentinels for other marine animals that strand during domoic acid poisoning events, including several species of dolphin and whales. Acute domoic acid poisoning is five-times more prominent in adult female sea lions as a result of the proximity of their year-round breeding grounds to major domoic acid bloom events. The chronic neurological syndrome, on the other hand, is more prevalent in young animals, with many potentially poisoned in utero. The sea lion rookeries of the Channel Islands are at the crossroads of domoic acid producing harmful algal blooms and a huge industrial discharge site for dichlorodiphenyltrichloroethane (DDTs). Studies in experimental animals suggest that chronic poisoning observed in immature sea lions may result from a spatial and temporal coincidence of DDTs and domoic acid during early life stages. Emergence of an epilepsy syndrome from the ocean brings a human epilepsy model to life and provides unexpected insights into interaction with legacy contaminants and expression of disease at different life stages

Discerning natural and anthropogenic organic matter inputs to salt marsh sediments of Ria Formosa lagoon (South Portugal)

Sedimentary organic matter (OM) origin and molecular composition provide useful information to understand carbon cycling in coastal wetlands. Core sediments from threors' Contributionse transects along Ria Formosa lagoon intertidal zone were analysed using analytical pyrolysis (Py-GC/MS) to determine composition, distribution and origin of sedimentary OM. The distribution of alkyl compounds (alkanes, alkanoic acids and alkan-2-ones), polycyclic aromatic hydrocarbons (PAHs), lignin-derived methoxyphenols, linear alkylbenzenes (LABs), steranes and hopanes indicated OM inputs to the intertidal environment from natural-autochthonous and allochthonous-as well as anthropogenic. Several n-alkane geochemical indices used to assess the distribution of main OM sources (terrestrial and marine) in the sediments indicate that algal and aquatic macrophyte derived OM inputs dominated over terrigenous plant sources. The lignin-derived methoxyphenol assemblage, dominated by vinylguaiacol and vinylsyringol derivatives in all sediments, points to large OM contribution from higher plants. The spatial distributions of PAHs (polyaromatic hydrocarbons) showed that most pollution sources were mixed sources including both pyrogenic and petrogenic. Low carbon preference indexes (CPI > 1) for n-alkanes, the presence of UCM (unresolved complex mixture) and the distribution of hopanes (C-29-C-36) and steranes (C-27-C-29) suggested localized petroleum-derived hydrocarbon inputs to the core sediments. Series of LABs were found in most sediment samples also pointing to domestic sewage anthropogenic contributions to the sediment OM.EU Erasmus Mundus Joint Doctorate fellowship (FUECA, University of Cadiz, Spain)EUEuropean Commission [FP7-ENV-2011, 282845, FP7-534 ENV-2012, 308392]MINECO project INTERCARBON [CGL2016-78937-R]info:eu-repo/semantics/publishedVersio