Instability Resistance Training Decreases Motor Noise During Challenging Walking Tasks in Older Adults: A 10-Week Double-Blinded RCT

Locomotor stability is challenged by internal perturbations, e.g., motor noise, and external perturbations, e.g., changes in surface compliance. One means to compensate for such perturbations is to employ motor synergies, defined here as co-variation among a set of elements that acts to stabilize, or provide similar trial-to-trial (or step-to-step) output, even in the presence of small variations in initial conditions. Whereas evidence exists that synergies related to the upper extremities can be trained, the extent to which lower limb synergies, such as those which may be needed to successfully locomote in complex environments, remains unknown. The purpose of this study was to evaluate if resistance training (RT) in unstable environments could promote coordination patterns associated with stronger synergies during gait. Sixty-eight participants between the age of 65 and 80 were randomly assigned to one of three different RT modalities: stable whole-limb machine-based RT (S-MRT), instability free-weight RT (I-FRT), and stable machine-based adductor/abductor RT (S-MRTHIP). Before and after RT, participants walked across an even lab floor and a more challenging uneven surface with and without holding a weighted bag. The uncontrolled manifold control analysis (UCM) was used to calculate the synergy index (i.e., strength of the kinematic synergy) related to stabilization of our performance variable, the mediolateral trajectory of the swing foot, under each condition. Regardless of RT group, there was no effect of RT on the synergy index when walking across the even lab floor. However, the synergy index during the two uneven surface conditions was stronger after I-FRT but was not affected by the other RT modalities. The stronger synergy index for the I-FRT group was due to improved coordination as quantified by an overall increase in variability in elemental variable space but a decrease in the variability that negatively affects performance. The unstable environment offered by I-FRT allows for exploration of motor solutions in a manner that appears to transfer to challenging locomotor tasks. Introducing tasks that promote, rather than limit, exploration of motor solutions seems to be a valuable exercise modality to strengthen kinematic synergies that cannot be achieved with traditional strengthening paradigms (e.g., S-MRT).Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT03017365

Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 5: Variability of the ultraviolet continuum and emission lines of NGC 3783

We report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of 7 months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line fluxes. The light curves for the continuum fluxes exhibited two well-defined local minima or 'dips,' the first lasting is less than or approximately 20 days and the second is less than or approximately 4 days, with additional episodes of relatively rapid flickering of approximately the same amplitude. As in the case of NGC 5548 (the only other Seyfert galaxy that has been the subject of such an intensive, sustained monitoring effort), the largest continuum variations were seen at the shortest wavelengths, so that the continuum became 'harder' when brighter. The variations in the continuum occurred simultaneously at all wavelengths (delta(t) is less than 2 days). Generally, the amplitude of variability of the emission lines was lower than (or comparable to) that of the continuum. Apart from Mg II (which varied little) and N V (which is relatively weak and badly blended with Ly(alpha), the light curves of the emission lines are very similar to the continuum light curves, in each case with a small systematic delay or 'lag.' As for NGC 5548, the highest ionization lines seem to respond with shorter lags than the lower ionization lines. The lags found for NGC 3783 are considerably shorter than those obtained for NGC 5548, with values of (formally) approximately 0 days for He II + O III), and approximately 4 days for Ly(alpha) and C IV. The data further suggest lags of approximately 4 days for Si IV + O IV) and 8-30 days for Si III + C III). Mg II lagged the 1460 A continuum by approximately 9 days, although this result depends on the method of measuring the line flux and may in fact be due to variability of the underlying Fe II lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over timescales of is less than or approximately 2 days, and that the character of the continuum variability may change with time

Instability Resistance Training Decreases Motor Noise During Challenging Walking Tasks in Older Adults: A 10-Week Double-Blinded RCT

Gefördert durch den Publikationsfonds der Universität Kasse

Structural integrity of custom-designed additive manufactured prosthetic sockets compared to traditional sockets

Over the past decades, the number of patients with lower extremity amputation increased world-wide. The increasing rate of patients, particularly in developing countries, has led to limited access to clinics and services for prosthetic and orthotic care. Additive manufacturing has rapidly evolved over the last decade and is opening new possibilities for prosthetics and orthotics. 3D printed prosthetic sockets are a promising solution to reduce access- or cost-related barriers to prosthesis use since 3D printed prosthetic sockets can be manufactured at an affordable cost and quickly delivered to patients. We sought to compare the ultimate strength of 3D printed sockets made of different filaments (polyethylene terephthalate glycol, polycarbonate, and co-polymer polypropylene) with that of traditionally fabricated sockets (laminated composite sockets and thermoplastic sockets) and to examine whether the strength of 3D printed sockets could be improved through iterative design changes focused on reinforcing the distal end of the socket. All sockets were mechanically tested in accordance with ISO 10328 standards. Although the strength of all of the 3D printed sockets was weaker than that of laminated composite sockets, design modifications to reinforce the distal end improved the strength of 3D printed sockets made of polycarbonate and polypropylene (but not polyethylene terephthalate glycol), resulting in ultimate strengths and stiffnesses that were comparable to the traditionally fabricated thermoplastic socket. In addition, our results demonstrated that socket failure occurred mainly at the distal end regardless of material type. The strength of some 3D printed sockets under limited testing conditions showed promise to be used for clinical purpose, especially when the socket was reinforced with distal struts

Sensitivity of Dynamic Stability to Changes in Step Width During Treadmill Walking by Young Adults

Recent experimental findings support theoretical predictions that across walking conditions the motor system chooses foot placement to achieve a constant minimum "margin of stability" (MOSmin)-distance between the extrapolated center of mass and base of support. For example, while step width varies, similar average MOSmin exists between overground and treadmill walking and between overground and compliant/irregular surface walking. However, predictions regarding the invariance of MOSmin to step-by-step changes in foot placement cannot be verified by average values. The purpose of this study was to determine average changes in, and the sensitivity of MOSmin to varying step widths during two walking tasks. Eight young subjects walked on a dual-belt treadmill before and after receiving information that stepping on the physical gap between the belts causes no adverse effects. Information decreased step width by 17% (p = .01), whereas MOSmin was unaffected (p = .12). Regardless of information, subject-specific regressions between step-by-step values of step width and MOSmin explained, on average, only 5% of the shared variance (beta = 0.11 +/- 0.05). Thus, MOSmin appears to be insensitive to changing step width. Accordingly, during treadmill walking, step width is chosen to maintain MOSmin. If MOSmin remains insensitive to step width across other dynamic tasks, then assessing an individual's stability while performing theses tasks could help describe the health of the motor system

Larvicidal Activity of Carbon Black against the Yellow Fever Mosquito Aedes aegypti

The yellow fever mosquito Aedes aegypti is one of the deadliest animals on the planet because it transmits several medically important arboviruses, including Zika, chikungunya, dengue, and yellow fever. Carbon-based nanoparticles (CNPs) derived from natural sources have previously been shown to have toxic effects on mosquito larvae and offer a potential alternative to chemical insecticides such as pyrethroids, for which mosquitoes have evolved resistance. However, CNPs derived from industrial sources, such as carbon black, have not previously been evaluated as larvicides. Here, we evaluate the effects of a commercially-available carbon black, EMPEROR® 1800 (E1800), on mortality and development of pyrethroid-susceptible (PS) and pyrethroid-resistant (PR) strains of Ae. aegypti. We found that E1800 exhibited concentration-dependent mortality against 1st instar larvae of both strains within the first 120 h after exposure, but after this period, surviving larvae did not show delays in their development to adults. Physical characterization of E1800 suspensions suggests that they form primary particles of ~30 nm in diameter that fuse into fundamental aggregates of ~170 nm in diameter. Notably, larvae treated with E1800 showed internal accumulation of E1800 in the gut and external accumulation on the respiratory siphon, anal papillae, and setae, suggesting a physical mode of toxic action. Taken together, our results suggest that E1800 has potential use as a larvicide with a novel mode of action for controlling PS and PR mosquitoes

Fear of Falling Does Not Alter the Kinematics of Recovery from an Induced Trip: A Preliminary Study

Objective: To provide preliminary information about the relationships between self-reported fear of falling (FOF) in healthy community-dwelling women, the number of falls, and recovery kinematics in response to a laboratory-induced trip. Design: Cohort study Setting: Clinical research laboratory Participants: A subset of community dwelling older women (N=33) recruited from studies of laboratory induced trips and fall-prevention. Intervention: A laboratory-induced trip. Main Outcome Measures: The number of fallers in the FOF vs. the control group. Recovery kinematics of FOF falls vs. control group falls, and FOF recoveries vs. control group recoveries were compared. The degree of FOF was assessed by Activities Balance Confidence Scale(ABC). Results: Falls occurred in 6/14 (43%) of the FOF and 4/16 (25%) of control subjects (p=0.26). Kinematics of FOF falls were similar to those of control falls. At the completion of the initialrecovery step, FOF showed significantly greater trunk extension velocity than controls (-82.1±- 66.1 vs. -25.0±-53.0 degrees/sec respectively; p=0.05). All other variables were not significantly different. ABC scores of FOF subjects did not differ significantly between fallers and those who recovered (mean=75.2±5.6, 71.1±11.8, respectively; p=0.84). Conclusion: Healthy community-dwelling older adults would benefit from fall prevention, regardless of the presence of self-reported FOF

Effects of Advanced Age and Parkinson’s Disease on Joint-Level Kinetic Adaptations to Faster Walking Speeds

Redistribution of mechanical output from the ankle to the hip during walking occurs with advanced age. Changes to tissues spanning the ankle may limit the joint from performing mechanical functions necessary to walk at fast speeds and older adults may redistribute work proximally to compensate. Older adults with Parkinson’s disease (PD) do not exhibit the distal-to-proximal redistribution and may therefore be limited in reaching fast walking speeds. We tested whether advanced aging, regardless of the presence of PD, limits the ability to increase motor-like behavior of the ankle as walking speed increases. We also tested whether healthy older adults—but not PD patients—would compensate for reduced motor-like behavior at the ankle with disproportionately larger mechanical redistributions at faster speeds. The 16 young, 16 older, and 8 PD-diagnosed adults walked at 0.8, 1.2, and 1.6 ms−1 on a treadmill. We used joint functional indexing to quantify motor-like behavior of the ankle and a hip-to-ankle mechanical work ratio to quantify mechanical redistribution. We found a significant group x speed interaction (p < 0.05) for motor-like behavior of the ankle, with younger adults increasing motor index more than the older and PD groups as walking speed increased. Contrary to our second hypothesis, we found a significant main effect of speed (p < 0.001) on redistribution ratios, indicating that all three groups decreased redistribution ratios as walking speed increased, but not a significant interaction