How groundwater time series and aquifer property data explain heterogeneity in the Permo-Triassic sandstone aquifers of the Eden Valley, Cumbria, UK

A novel investigation of the impact of meteorological and geological heterogeneity within the Permo-Triassic Sandstone aquifers of the River Eden catchment, Cumbria (UK), is described. Quantifying the impact of heterogeneity on the water cycle is increasingly important to sustainably manage water resources and minimise flood risk. Traditional investigations on heterogeneity at the catchment scale require a considerable amount of data, and this has led to the analysis of available time series to interpret the impact of heterogeneity. The current research integrated groundwater-level and meteorological time series in conjunction with aquifer property data at 11 borehole locations to quantify the impact of heterogeneity and inform the hydrogeological conceptual understanding. The study visually categorised and used seasonal trend decomposition by LOESS (STL) on 11 groundwater and meteorological time series. Decomposition components of the different time series were compared using variance ratios. Though the Eden catchment exhibits highly heterogeneous rainfall distribution, comparative analysis at borehole locations showed that (1) meteorological drivers at borehole locations are broadly homogeneous and (2) the meteorological drivers are not sufficient to generate the variation observed in the groundwater-level time series. Three distinct hydrogeological regimes were identified and shown to coincide with heterogeneous features in the southern Brockram facies, which is the northern silicified region of the Penrith Sandstone and the St Bees Sandstone. The use of STL analysis in combination with detailed aquifer property data is a low-impact insightful investigative tool that helps guide the development of hydrogeological conceptual models

Real-time fluorescence lifetime imaging system with a 32 × 32 0.13um CMOS low dark-count single-photon avalanche diode array

A compact real-time fluorescence lifetime imaging microscopy (FLIM) system based on an array of low dark count 0.13?m CMOS singlephoton avalanche diodes (SPADs) is demonstrated. Fast background-insensitive fluorescence lifetime determination is achieved by use of a recently proposed algorithm called ‘Integration for Extraction Method’ (IEM) [J. Opt. Soc. Am. A 25, 1190 (2008)]. Here, IEM is modified for a wider resolvability range and implemented on the FPGA of the new SPAD array imager. We experimentally demonstrate that the dynamic range and accuracy of calculated lifetimes of this new camera is suitable for widefield FLIM applications by imaging a variety of test samples, including various standard fluorophores covering a lifetime range from 1.6ns to 16ns, microfluidic mixing of fluorophore solutions, and living fungal spores of Neurospora Crassa. The calculated lifetimes are in a good agreement with literature values. Real-time fluorescence lifetime imaging is also achieved, by performing parallel 32 × 16 lifetime calculations, realizing a compact and low-cost FLIM camera and promising for bigger detector arrays.Micro ElectronicsElectrical Engineering, Mathematics and Computer Scienc