Longitudinal Changes in Temporospatial Gait Characteristics during the First Year Post-Stroke

Given the paucity of longitudinal data in gait recovery after stroke, we compared temporospatial gait characteristics of stroke patients during subacute (<2 months post-onset, T0) and at approximately 6 and 12 months post-onset (T1 and T2, respectively) and explored the relationship between gait characteristics at T0 and the changes in gait speed from T0 to T1. Forty-six participants were assessed at T0 and a subsample of 24 participants at T2. Outcome measures included Fugl-Meyer lower-extremity motor score, 14 temporospatial gait parameters and symmetry indices of 5 step parameters. Except for step width, all temporospatial parameters improved from T0 to T1 (p ≤ 0.0001). Additionally, significant improvements in symmetry were found for the initial double-support time and single-support time (p ≤ 0.0001). Although group results at T2 were not different from those at T1, the individual analysis revealed that 42% (10/24) of the subsample showed a significant increase in gait speed. The increase in gait speed from T0 to T1 was negatively correlated with gait speed and stride length, and positively correlated with the symmetry indices of stance and single-support times at T0 (p ≤ 0.002). Temporospatial gait parameters and stance time symmetry improve over the first 6 months after stroke with an apparent plateau thereafter. Approximately 40% of the subsample continue to increase gait speed from 6 to 12 months post-stroke. A greater increase in gait speed during the first 6 months post-stroke is associated with initially slower walking, shorter stride length, and more pronounced asymmetry in stance and single-support times. The improvement in lower-extremity motor function and bilateral improvements in step parameters collectively suggest that gait changes over the first 12 months after stroke are likely due to neurological recovery, although some compensation by the non-paretic side cannot be excluded.

A Response Surface Methodology to Optimize Multiple Discharge Step Parameters for Sinking Electrical Discharge Machining

Conventional die-sinking electrical discharge machining (EDM) employs a single electrode operating under constant discharge conditions. We explored a two-electrode scenario, in which roughing and finishing were coupled. We developed a multiple discharge step (MDS) method that uses three discharge depths. The discharge current is highest in step 1 and lowest in step 3. Response surface methodology (RSM) was employed to optimize the discharge conditions. Experimentally, the MDS method combined with RSM decreased electrode edge wear and surface roughness compared to the conventional method, with no increase in the average discharge current.

Dynamic Asymmetries Do Not Match Spatiotemporal Step Asymmetries during Split-Belt Walking

While walking on split-belt treadmills (two belts running at different speeds), the slower limb shows longer anterior steps than the limb dragged by the faster belt. After returning to basal conditions, the step length asymmetry is transiently reversed (after-effect). The lower limb joint dynamics, however, were not thoroughly investigated. In this study, 12 healthy adults walked on a force-sensorised split-belt treadmill for 15 min. Belts rotated at 0.4 m s−1 on both sides, or 0.4 and 1.2 m s−1 under the non-dominant and dominant legs, respectively. Spatiotemporal step parameters, ankle power and work, and the actual mean velocity of the body’s centre of mass (CoM) were computed. On the faster side, ankle power and work increased, while step length and stance time decreased. The mean velocity of the CoM slightly decreased. As an after-effect, modest converse asymmetries developed, fading within 2–5 min. These results may help to decide which belt should be assigned to the paretic and the unaffected lower limb when split-belt walking is applied for rehabilitation research in hemiparesis.

COOLANT TEST AT THE PROCESS OF FLAT INFEED GRINDING OF TITANIUM ALLOY

When grinding the VT9 titanium alloy, the following types of coolant were tested: an aqueous solution of sodium phosphate trisubstituted o, semi-synthetic with extreme pressure additives, synthetic universal and standard. The height and step parameters of the roughness of the treated surface, the grinding coefficient are determined. The correlation coefficients between these parameters are calculated. The differences in the morphology of the polished surface are shown.

Effect of K2ZrF6 Concentration on the Two-Step PEO Coating Prepared on AZ91 Mg Alloy in Alkaline Silicate Solution

In this study, a two-step Plasma Electrolytic Oxidation (PEO) method with constant primary step parameters and varying K2ZrF6 concentration in the secondary electrolyte solution was carried out to obtain a hard and dense coating on AZ91D alloy. For lower concentrations of K2ZrF6, a mixture of granular and pancake structure with higher surface porosity was obtained. Increasing the concentration up to 6 g/L caused the granular structure to disappear and a significant decrease was observed in the surface porosity as well as inner layer damage. Due to the compact inner layer structure, significant improvement in the corrosion resistance and mechanical properties of the AZ91 was observed with K2ZrF6 concentration. Highest values of hardness and corrosion resistance, i.e., 1589.45 HV and 386.30 × 103 Ω cm2, respectively, were obtained for a 6 g/L K2ZrF6 concentration.

Genome dashboards: Framework and Examples

ABSTRACTGenomics is a sequence-based informatics science and a 3D structure-based material science. Here we describe a framework for developing genome dashboards specifically designed to unify informatics with studies of chromatin structure and dynamics. The framework is based on the mathematical representation of geometrically exact rod models and the generalization of DNA base pair step parameters. A Model-View-Controller software design approach is proposed to implement genome dashboards as finite state machines either as desktop or web based applications. Two examples are demonstrated using our minimal genome dashboard called G-Dash-min. The data unification achieved with a genome dashboard supports the bi-directional exchange of data between informatics and structure. Thus any experimentally or theoretically determined sequence based informatics track can inform DNA, nucleosome or chromatin modeling (e.g. nucleosome positions) and structure features can be analyzed as informatics tracks in a genome browser (e.g. DNA base pair step parameters: Roll, Tilt, Twist). Here the framework is applied to chromatin, but genome dashboards are more broadly applicable. Genome dashboards are a novel means of investigating structure-function relationships for regions of the genome ranging from base pairs to entire chromosomes and for generating, validating, and testing mechanistic hypotheses.

PECULIARITIES IN ROUGHNESS FORMATION OF CONJUGATE CYLINDRICAL AND END SURFACES OF PARTS AT GRINDING WITH ONE TOOL

The paper reports the study of peculiarities in the roughness formation of conjugate cylindrical and end surfaces of machinery at their simultaneous grind-ing with the disk periphery and the end. The analytical dependences for the computation of altitude and step parameters of surface roughness at simultaneous grinding with disk periphery and butt are obtained the authenticity of which is confirmed in the course of experimental investigations. It is defined that altitude and step roughness parameters of cylindrical surfaces and end surfaces conjugate with them after their simultaneous grinding may differ up to 2-3 times. Lesser roughness is formed on end surfaces which is explained by the large number of disk grain tips contacting with given surfaces of a blank. The roughness step parameters of ground surfaces are influenced considerably by a rounding radius of abrasive grain tips at that the average step of unevenness along a middle line Sm is threefour times greater than the average step S on tips. It is shown that a considerable impact of abrasive tool characteristics and time of surface processing with a grinding disk upon parameters of roughness in conjugate surfaces of parts. Recommendations scientifically substantiated are formulated on the technological support of surface roughness parameter aggregate at simultaneous grind-ing with the disk periphery and the end.