The case for support of manned spaceflight as a platform for research on sarcopenia and osteopenia

The United Kingdom government has decided to be part of the European Space Agency’s Aurora programme, but so far it has declared an intention only to participate in aspects of the programme which do not involve human space flight. Personally, we believe this to be a mistake, mainly because of the inherent limitations of robots, especially in unforeseen circumstances. However the arguments we make are different to this and are focussed mainly upon the benefits to earth based science, medicine, technology and education which would accrue from a manned space flight programme.     

Geomorphological effectiveness of floods to rework gravel bars: Insight from hyperscale topography and hydraulic modelling

Bars are key morphological units in river systems, fashioning the sediment regime and bedload transport processes within a reach. Reworking of these features underpins channel adjustment at larger scales, thereby acting as a key determinant of channel stability. Despite their importance to channel evolution, few investigations have acquired spatially continuous data on bar morphology and sediment-size to investigate bar reworking. To this end, four bars along a 10 km reach of a wandering gravel-bed river were surveyed with terrestrial laser scanning (TLS), comparing downstream changes in slope, bed material size and channel planform. Detrended standard deviations (σ_z) were extracted from TLS point clouds and correlated to underlying physically measured median grain-size (D₅₀), across a greater range of σ_z values than have hitherto been reported. The resulting linear regression model was used to create a 1 m resolution median grain-size map. A fusion of airborne LiDAR and optical-empirical bathymetric mapping was used to develop reach-scale digital elevation models (DEMs) for rapid two-dimensional hydraulic modelling using JFlow® software. The ratio of dimensionless shear stress over critical shear stress was calculated for each raster cell to calculate the effectiveness of a range of flood events (2.33–100 year recurrence intervals) to entrain sediment and rework bar units. Results show that multiple bar forming discharges exist, whereby frequent flood flows rework tail and back channel areas, while much larger, less frequent floods are required to mobilise the coarser sediment fraction on bar heads. Valley confinement is shown to exert a primary influence on patterns of bar reworking. Historical aerial photography, hyperscale DEMs and hydraulic modelling are used to explain channel adjustment at the reach scale. The proportion of the bar comprised of more frequently entrained units (tail, back channel, supra-platform) relative to more static units (bar head) exerts a direct influence upon geomorphic sensitivity. © 2018 John Wiley & Sons, Ltd.     

The TAP III beamforming system

The Three-Array Processor (TAP III) beamforming system incorporating both wide-band time-domain beamforming and narrow-band frequency-domain beamforming is described. This paper briefly develops the beamforming theory and shows how the fast Fourier transform (FFT) is applied to accomplish frequency-domain beamforming. The frequency-domain beamformer operates in the frequency domain to form beams and power spectrum data over narrow frequency bands of interest. A real-time digital filtering technique is used to extract the narrow bands of interest from the broad-band input signal. The frequency-domain beamformer accomplishes real-time digital filtering and beamforming by using a high-speed array processor to do the complex calculations and data handling required by the algorithm. The time-domain beamformer operates in parallel with the frequency-domain beamformer to form up to 16 broad-band beams in the time domain. A programmable all-pass digital filter is used to create the fine time delays required by the time-domain beamformer.     

The disturbing case of the concentration of power in human geography

The increasing concentration of power in academic disciplines with the introduction of Research Assessment Exercises is noted. The case of human geography in the UK is discussed.     

Model structure and uncertainty for stochastic non-point source modelling applications

Abstract

The uncertainty associated with a rainfall–runoff and non-point source loading (NPS) model can be attributed to both the parameterization and model structure. An interesting implication of the areal nature of NPS models is the direct relationship between model structure (i.e. sub-watershed size) and sample size for the parameterization of spatial data. The approach of this research is to find structural limitations in scale for the use of the conceptual NPS model, then examine the scales at which suitable stochastic depictions of key parameter sets can be generated. The overlapping regions are optimal (and possibly the only suitable regions) for conducting meaningful stochastic analysis with a given NPS model. Previous work has sought to find optimal scales for deterministic analysis (where, in fact, calibration can be adjusted to compensate for sub-optimal scale selection); however, analysis of stochastic suitability and uncertainty associated with both the conceptual model and the parameter set, as presented here, is novel; as is the strategy of delineating a watershed based on the uncertainty distribution. The results of this paper demonstrate a narrow range of acceptable model structure for stochastic analysis in the chosen NPS model. In the case examined, the uncertainties associated with parameterization and parameter sensitivity are shown to be outweighed in significance by those resulting from structural and conceptual decisions.

Citation Parker, G. T. Rennie, C. D. & Droste, R. L. (2011) Model structure and uncertainty for stochastic non-point source modelling applications. Hydrol. Sci. J. 56(5), 870–882.     

A semi-empirical approach for estimation of bed shear stress in a tailings pond

Wind-driven waves and currents exert shear stress on the bed of a tailings pond. A semi-empirical approach for estimating this bed shear stress is presented in this paper. For the first time in a mine tailings storage facility, the current-induced component of the bed shear stress was obtained using 1,200-kHz acoustic Doppler current profiler measurements of in situ currents and a log-law fit to the mean velocity profiles, while the wave-induced portion was calculated using empirical wave hindcasting equations. The total bed shear stress was obtained by non-linear addition of wave and current components using a wave–current interaction approach. The study was conducted in the middle cell of the Shebandowan tailings storage facility, northern Ontario, Canada. The measured currents facilitated the visualization of the complex near-bed circulatory flow pattern in the pond. The estimated combined wave–current bed shear stress varied from 0.0006 to 0.16 Pa with an average value of 0.028 Pa. The results also showed that linear addition of bed shear stresses due to waves and currents could underestimate the total bed shear stress. A comparison of the results of the present work to those of previous studies suggests that it is more reliable to obtain current-induced bed shear stress from field measurements than to estimate it from empirical equations.