Locomotor adaptation is influenced by the interaction between perturbation and baseline asymmetry after stroke.

Stroke survivors without cerebellar involvement retain the ability to adapt to the split-belt treadmill; however it has been suggested that their rate of adaptation may be slowed compared to those who are neurologically intact. Depending on limb placement, the split-belt treadmill can be configured to either exaggerate baseline asymmetry, or reduce it, which may affect the behavior of adaptation or de-adaptation. The objectives of this study were to characterize the rate and magnitude of locomotor (de)adaptation in chronic stroke survivors compared to healthy matched subjects, and to evaluate whether exaggeration or reduction of baseline asymmetry impact the responses. Seventeen stroke survivors and healthy subjects completed 10min of split-belt treadmill walking, then 5min of tied-belt walking. Stroke survivors completed this once with each leg on the fast belt. Magnitude and rate of (de)adaptation were evaluated for step length and limb phase asymmetry. There were no differences between the groups with the exception of the reduced step length asymmetry configuration, in which case there was a significantly reduced magnitude (p≤0.000) and rate (p=0.011) of adaptation when compared to controls. There was a similar trend observed during post-adaptation for the exaggerated asymmetry group. The rate and magnitude of locomotor (de)adaptation is similar between chronic stroke survivors and neurologically intact controls, except when the adaptation or de-adaptation response would take the stroke survivors away from a symmetric step length pattern. This suggests that there may be some benefit to symmetry that is recognized by the system

Transition to forefoot strike reduces load rates more effectively than altered cadence

Background Excessive vertical impacts at landing are associated with common running injuries. Two primary gait-retraining interventions aimed at reducing impact forces are transition to forefoot strike (FFS) and increasing cadence (CAD). The objective of this study was to compare the short- and long-term effects of 2 gait-retraining interventions aimed at reducing landing impacts. Methods A total of 39 healthy recreational runners using a rearfoot strike and a CAD of ≤170 steps/min were randomized into CAD or FFS groups. All participants performed 4 weeks of strengthening followed by 8 sessions of gait-retraining using auditory feedback. Vertical average load rates (VALR) and vertical instantaneous load rates were calculated from the vertical ground reaction force curve. Both CAD and foot strike angle were measured using 3-dimensional motion analysis and an instrumented treadmill at baseline and at 1 week, 1 month, and 6 months after retraining. Results Analysis of variance revealed that the FFS group had significant reductions in VALR (49.7%) and vertical instantaneous load rates (41.7%), and changes were maintained long term. Foot strike angle in the FFS group changed from 14.2° dorsiflexion at baseline to 3.4° plantarflexion, with changes maintained long term. The CAD group exhibited significant reduction only in VALR (16%) and only at 6 months. Both groups had significant and similar increases in CAD at all follow-ups (CAD, +7.2% to 173 steps/min; and FFS, +6.1% to 172 steps/min). Conclusion FFS gait-retraining resulted in significantly greater reductions in VALR and similar increases in CAD compared to CAD gait-retraining in the short and long term. CAD gait-retraining resulted in small reductions in VALR at only the 6-month follow-up

Enabling Precision Medicine in Cancer Care Through a Molecular Data Warehouse: The Moffitt Experience

PURPOSE: The use of genomics within cancer research and clinical oncology practice has become commonplace. Efforts such as The Cancer Genome Atlas have characterized the cancer genome and suggested a wealth of targets for implementing precision medicine strategies for patients with cancer. The data produced from research studies and clinical care have many potential secondary uses beyond their originally intended purpose. Effective storage, query, retrieval, and visualization of these data are essential to create an infrastructure to enable new discoveries in cancer research. METHODS: Moffitt Cancer Center implemented a molecular data warehouse to complement the extensive enterprise clinical data warehouse (Health and Research Informatics). Seven different sequencing experiment types were included in the warehouse, with data from institutional research studies and clinical sequencing. RESULTS: The implementation of the molecular warehouse involved the close collaboration of many teams with different expertise and a use case-focused approach. Cornerstones of project success included project planning, open communication, institutional buy-in, piloting the implementation, implementing custom solutions to address specific problems, data quality improvement, and data governance, unique aspects of which are featured here. We describe our experience in selecting, configuring, and loading molecular data into the molecular data warehouse. Specifically, we developed solutions for heterogeneous genomic sequencing cohorts (many different platforms) and integration with our existing clinical data warehouse. CONCLUSION: The implementation was ultimately successful despite challenges encountered, many of which can be generalized to other research cancer centers

Dynamics, acoustics and control of cloud cavitation on hydrofoils

Cloud-cavitation, often formed by the breakdown and collapse of a sheet or vortex cavity, is responsible for severe cavitation noise and erosion damage. This thesis describes an experimental investigation of the dynamics and acoustics of cloud cavitation on a three dimensional hydrofoil and examines the injection of air as a means of noise suppression. Part one of this work examines the large amplitude impulsive pressures which were measured on the suction surface of an oscillating hydrofoil experiencing cloud cavitation and these pressure pulses are correlated with the observation of shock waves propagating through the bubbly mixture. Recess mounted transducers were used to measure unsteady pressures at four locations along the chord of the suction surface of a hydrofoil. By examining the transducer output, two distinct types of pressure pulses were identified. Local pulses occurred at a single transducer location and were randomly distributed in position and time. Conversely, global pulses were registered by all the transducers almost simultaneously. The location of the global pulses relative to the foil oscillation was quite repeatable and these events produced substantial far-field noise. Correlation of the transducer output with high speed movies of the cavitation revealed that the global pulses were produced by a large scale collapse of the bubble cloud. Conversely, local pulses were generated by local disturbances in the bubbly mixture characterized by large changes in void fraction. The large pressure pulse associated with the local and global cavitation structures, the geometric coherence of their boundaries and the nearly discrete change in void fraction across the boundaries of these structures indicate that these structures consist of bubbly shock waves. Qualitative and quantitative comparisons between the current experiments and the numerical, analytic and experimental bubbly shock wave analysis of other investigators support this conclusion. Part two of this work examines the dramatic reduction in cloud cavitation noise due to both continuous and pulsed injection of air into the cavitating region of the foil. At sufficient air flow rates, the radiated noise could be reduced by a factor greater than 200 relative to the noise produced without air injection. Unsteady surface pressure measurements also showed a reduction in the acoustic impulse with air injection by a factor of up to two orders of magnitude. An explanation for this noise reduction can be found by examining the high speed motion pictures. The presence of the non-condensible gas in the cavitation cloud is shown to prevent any rapid or coherent collapse process. Although the formation of local structures is still observed, the presence of air in the bubbles diminishes both the magnitude and the frequency of occurrence of local pressure pulses. Finally, pulsed air injection results in a lower acoustic impulse than the impulse obtained by injecting the same mass of air continuously over the entire oscillation cycle