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This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.Networks of rain-gauges provide an accurate but highly localized measure of rainfall, with limited coverage and resolution, whereas radars provide rain-rate and accumulation estimates over wide areas at high spatial and temporal resolution but low accuracy. When quantifying rainfall accumulations for applications such as flood forecasting, combining the two sets of data can be beneficial for producing a high-resolution merged product with a lower error than the gauge-only or the radar-only product. In this study, three kriging methods (kriging with external drift (KED), kriging with radar-based error correction (KRE) and ordinary kriging (OK)) as well as a multiquadric (MQ) scheme have been used to merge radar and gauge data. The results were cross-validated with true rainfall readings at the surface for a number of different meteorological events covering England and Wales. Overall, all the merging schemes trialled produced a merged product that was superior to the individual radar or gauge data. The KED was the best performing method across all rainfall thresholds and meteorological conditions, with the use of a parametric variogram best suited to short (15 min) accumulation periods and a non-parametric variogram preferable for hourly accumulations. The study also shows that the merged product deteriorates when the gauge-network density is reduced; exceptions to this are made in situations where spatially isolated rainfall is observed by the radar and where the gauges that are found least likely to represent the rainfall are carefully removed prior to merging. The latter process was found to improve the quality of the merged product, regardless of the meteorological conditions, providing a viable method for producing a KED-based merging scheme that is applicable to all meteorological conditions.

The alignment properties and distribution of flow speed during Poiseuille flow through a microchannel of a nematic liquid crystal in a cell with homeotropic surface alignment has been measured using a combination of conoscopy, fluorescence confocal polarizing microscopy, and time-lapse imaging. Two topologically distinct director profiles, with associated fluid velocity fields, are found to exist with the preferred state dictated by the volumetric flow rate of the liquid crystal. The results show excellent agreement with model data produced using the Ericksen-Leslie nematodynamics theory.

The membrane dipole potential (ψ(d)) is an important biophysical determinant of membrane function and a sensitive indicator of lipid organisation. In this study we have used the environmentally sensitive probe di-8-anepps to explore the effects of oxidative stress on the membrane dipole potential of human erythrocytes. Cells suspended in 0.15mM phosphate buffered saline containing 0.1mg/ml albumin maintained a mean value for ψ(d) of 270 (±20) mV over the course of 1hour. In the presence of 0.4mM cumene hydroperoxide there was an increase in ψ(d) of 14 (±7)%, accompanied by a decrease in cell diameter of ~14 (±2)%. Exposure of the cells to 0.4mM hydrogen peroxide caused ψ(d) to decrease by 13 (±8)% at the centre of the cell and 8 (±5)% at the edge whilst the diameter remained constant. In both cases the changes were equivalent to a change in transmembrane electric field of a magnitude of ~10MVm(-1), sufficient to influence membrane function. Raman microspectrometry supported the conclusion that cumene exerts its effect primarily on membrane lipids whilst hydrogen peroxide causes the formation of spectrin-haemoglobin complexes which stiffen the membrane.

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