VALIDITY OF A TREADMILL-MOUNTED PHOTOELECTRIC SYSTEM FOR MEASURING SPATIOTEMPORAL PARAMETERS OVER A RANGE OF RUNNING SPEEDS

The purpose of this study was to determine the concurrent validity of a treadmill-mounted photoelectric system (Optojump) for measuring spatiotemporal parameters of runners at a range of running speeds (12-16 km/h). Ten participants ran for 20 s at each of three different speeds (12, 14 and 16 km/h) on a HP Cosmos Pulsar treadmill while spatiotemporal parameters were measured by both the Optojump and a high-speed camera (960 fps). The Optojump was placed on the sides of the treadmill as per the manufacturer protocols. Large timing errors for contact time (13.1%) and swing time (6.8%) were recorded, while excellent validity was shown for the other parameters of stride time, stride length and stride frequency (errors less than 0.6%). Increases in gait speed resulted in significantly lower error values for both contact time and swing time, but had no effect on the other variables. Early identification of initial contact and delayed identification of toe-off in the Optojump system due to placement on the slightly elevated sides of the treadmill are hypothesised to be the cause of the notable errors in contact time and swing time. However, these systematic errors do not negatively affect the other spatiotemporal parameters of stride time, stride length and stride frequency which are all still accurately measured by the Optojump in this set-u

A general method for controlled nanopatterning of oxide dots: a microphase separated block copolymer platform

We demonstrate a facile, generic method for the fabrication of highly dense long range hexagonally ordered various inorganic oxide nanodots on different substrates by using a microphase separated polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer (BCP) thin film as a structural template. The method does not require complex co-ordination chemistry (between metal precursors and the polymer) and instead involves the simple, solution based chemistry applicable to a wide range of systems. A highly ordered PS-b-PEO thin film with perpendicularly oriented PEO cylinders is fabricated by solvent annealing over wafer scale. PEO cylinders are activated by ethanol to create a functional chemical pattern for nanodot development via spin coating and block selective metal ion inclusion. Subsequent UV/ozone treatment forms an ordered arrangement of oxide nanodots and removes the polymer components. The phase purity, crystallinity and thermal stability of these materials coupled to the ease of production may make them useful in technological applications. This method is particularly useful because the feature sizes can be tuned by changing the concentration of the precursors without changing the molecular weight and concentration of the block copolymer

USING BIRD STRIKE DATA TO MONITOR BIRD-HAZARD CONTROL

An effective definition of a bird strike is the basis for quantifying the scale of bird hazard problems. Here we present a working definition of a bird strike, which in turn forms the basis of an analysis of 32 years’ data collected at Dublin Airport, Ireland. A variety of datasets are analysed including the number of bird strikes per ten thousand aircraft movements, the mass of the bird species being struck, the time of year at which bird strikes occur and the dimensions of the aircraft utilising the airfield. In addition, we have analysed the mean number of strikes per year and the mean number of birds struck per bird strike. Following a very serious incident involving a Boeing 737-200 which struck a flock of gulls in the mid -1980’s, a new regime of control measures was put in place. Therefore our study permits us to evaluate the effectiveness of this management programme. The results suggest that the most significant impact of control measures is to reduce the number of birds being struck per bird strike

Erratum

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72954/1/j.1523-1739.1988.tb00160.x.pd

Selective sidewall wetting of polymer blocks in hydrogen silsesquioxane directed self-assembly of PS-b-PDMS

We show the importance of sidewall chemistry for the graphoepitaxial alignment of PS-b-PDMS using prepatterns fabricated by electron beam lithography of hydrogen silsesquioxane (HSQ) and by deep ultraviolet (DUV) lithography on SiO2 thin films. Density multiplication of polystyrene-block-polydimethylsiloxane (PS-b-PDMS) within both prepatterns was achieved by using a room temperature dynamic solvent annealing environment. Selective tuning of PS and PDMS wetting on the HSQ template sidewalls was also achieved through careful functionalization of the template and substrate surface using either brush or a self-assembled trimethylsilyl monolayer. PDMS selectively wets HSQ sidewalls treated with a brush layer of PDMS, whiereas PS is found to selectively wet HSQ sidewalls treated with hexamethyldisilazane (HMDS) to produce a trimethylsilyl-terminated surface. The etch resistance of the aligned polymer was also evaluated to understand the implications of using block copolymer patterns which have high etch resistance, self-forming (PDMS) wetting layers at both interfaces. The results outlined in this work may have direct applications in nanolithography for continued device scaling toward the end-of-roadmap era