Leg stiffness of sprinters using running-specific prostheses

Running-specific prostheses (RSF) are designed to replicate the spring-like nature of biological legs (bioL) during running. However, it is not clear how these devices affect whole leg stiffness characteristics or running dynamics over a range of speeds. We used a simple spring–mass model to examine running mechanics across a range of speeds, in unilateral and bilateral transtibial amputees and performance-matched controls. We found significant differences between the affected leg (AL) of unilateral amputees and both ALs of bilateral amputees compared with the bioL of non-amputees for nearly every variable measured. Leg stiffness remained constant or increased with speed in bioL, but decreased with speed in legs with RSPs. The decrease in leg stiffness in legs with RSPs was mainly owing to a combination of lower peak ground reaction forces and increased leg compression with increasing speeds. Leg stiffness is an important parameter affecting contact time and the force exerted on the ground. It is likely that the fixed stiffness of the prosthesis coupled with differences in the limb posture required to run with the prosthesis limits the ability to modulate whole leg stiffness and the ability to apply high vertical ground reaction forces during sprinting.     

Lower Extremity Exoskeletons and Active Orthoses: Challenges and State-of-the-Art

In the nearly six decades since researchers began to explore methods of creating them, exoskeletons have progressed from the stuff of science fiction to nearly commercialized products. While there are still many challenges associated with exoskeleton development that have yet to be perfected, the advances in the field have been enormous. In this paper, we review the history and discuss the state-of-the-art of lower limb exoskeletons and active orthoses. We provide a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and end with a discussion of the major advances that have been made and hurdles yet to be overcome.     

Simulated space environmental exposure of optical coatings for spacecraft solar rejection

Dielectric multilayers composed of niobium pentoxide and silicon dioxide, designed for broadband solar rejection, were exposed to a simulated space environment of ultraviolet light and low-energy (10-20-keV) electron radiation. Samples exhibited various degrees of exposure-induced absorption extending from the ultraviolet to the infrared. Processing variations were correlated to damage susceptibility, and methods were identified that produced parts that exhibited no degradation even though the same materials and coating design were used. Coatings prepared under energetic deposition conditions that provided the densest and most moisture-stable coatings exhibited the best stability to the exposure conditions used.     

Environmental-medical diagnosis and therapy. Hasty diagnosis of unspecified environmental syndromes should be avoided

In the past ten years environmental medicine has virtually exploded. Major instruments for the interdisciplinary environmental-medical diagnosis are history, on-site inspection, biomonitoring and ambient monitoring. Since the definitive diagnosis of an environment-related disease usually requires a joint evaluation of toxicological, somatic and psychosomatic findings, it is recommended that cooperation with an experienced center for environment medicine should be established early on. By doing so, an inappropriate diagnosis of unspecific environment-medical symptom complexes such as, e.g., multiple chemical sensitivity may be avoided. Such "diagnoses" may result in drastic, and for the patient and his family, often stressful, consequences.     

Sources of heavy metals and polycyclic aromatic hydrocarbons in urban stormwater runoff

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured in road debris collecting in urban areas and in the suspended sediment (SS) component of runoff from two stormwater catchments in Dunedin, New Zealand. Levels in the road debris ranged from 119-527 microg/g for lead, 50-464 microg/g for copper, 241-1 325 microg/g for zinc and 1.20-11.6 microg/g for sigma16PAH. The SS from the largely rural catchment (20% urban) had similar concentrations to the road debris, indicating that this urban material was the main source of the contaminants measured in the stormwater. Similar PAH fingerprint profiles and isomer ratios indicative of dominant pyrogenic (combustion) sources were also found in these two groups of materials. The SS from the 100% urban catchment contained 2- to 6-fold higher concentrations of metals and 10-fold greater levels of sigma16PAH. The higher levels of lead and copper were probably a result of industrial land uses in this catchment, while the additional zinc was linked to an abundance of zinc-galvanised roofing iron in the catchment's residential suburbs. The PAH profiles and isomer ratios were different for this urban catchment and suggested that a disused gasworks was contributing PAHs to the stormwater runoff.