Impaired H-Reflex Adaptations Following Slope Walking in Individuals With Post-stroke Hemiparesis

Background and Purpose: Short term adaptations in the Ia afferent-motoneuron pathway, as measured using the H-reflex, in response to altered ground reaction forces (GRFs) applied at the feet during slope walking have been observed in the non-impaired nervous system. The ability of the stroke-impaired nervous system to adapt to altered GRFs have not been examined. The purpose of this study was to examine the acute effects of altered propulsive and braking forces applied at the feet, which naturally occurs when walking on different slopes, on adaptations of the H-reflex pathway in individuals with chronic post-stroke hemiparesis

Formation mechanism of SiGe nanorod arrays by combining nanosphere lithography and Au-assisted chemical etching

The formation mechanism of SiGe nanorod (NR) arrays fabricated by combining nanosphere lithography and Au-assisted chemical etching has been investigated. By precisely controlling the etching rate and time, the lengths of SiGe NRs can be tuned from 300 nm to 1 μm. The morphologies of SiGe NRs were found to change dramatically by varying the etching temperatures. We propose a mechanism involving a locally temperature-sensitive redox reaction to explain this strong temperature dependence of the morphologies of SiGe NRs. At a lower etching temperature, both corrosion reaction and Au-assisted etching process were kinetically impeded, whereas at a higher temperature, Au-assisted anisotropic etching dominated the formation of SiGe NRs. With transmission electron microscopy and scanning electron microscopy analyses, this study provides a beneficial scheme to design and fabricate low-dimensional SiGe-based nanostructures for possible applications

Characterizing Intersection Variability of Butterfly Diagram in Post-stroke Gait Using Kernel Density Estimation

ackground:Center of pressure (COP) trajectory during treadmill walking have been commonly presented usingthe butterfly diagram to describe gait characteristics in neurologically intact and impaired individuals. However,due to the large amount of displayed information, the butterfly diagram is not an efficient solution to visualizelocomotor variability.Purpose:The purpose of this study was to evaluate post-stroke locomotor variability by applying Kernel densityestimation (KDE) on the intersections of the butterfly diagram, and to compare KDE derived metrics withconventional metrics of gait symmetry and variability.Methods:Bilateral toe-off(TO) and initial contact (IC) points of the butterfly diagram were determined to cal-culate the COP symmetry index and the intersections of bilateral TOeIC. Subsequently, the intersections duringthe walking window were used to evaluate its density and variability by Kernel density estimation. Standarddeviations of step width and step length were compared between groups.Results:Using the KDE surface plots we observed 4 characteristically different patterns with individuals post-stroke, which were associated with functional status quantified using walking speed and lower extremity Fugl-Meyer scores. However, locomotor variability quantified using standard deviations of step width and lengths didnot differ between groups.Significance & Novelty: This paper presents a novel approach of using KDE analysis as a better and moresensitive method to characterize locomotor COP variability in individuals with post-stroke hemiparesis, com-pared to conventional metrics of gait symmetry and variability