Morphodynamics, sedimentation and sediment dynamics of a gravel beach

The morphodyiiamics of a gravel barrier beadi in Devon, \JK (Slaptou Sands: tau/S 0.15 - 0.25, D50 2 - 8min), was studied with reference to its sedimentology. Three time scales were sampled for nearshore hydrodynamics, intertidal morphologies and sediirientologies. A series of surveys were carried out over individual tidal cycles (samphng every 5 - lOmins for between 6 and 91irs); on •consecutive low tides over half-lunar tidal cycles (1 -2 cross-shore profiles-sampled every 0.5 - Ini, on 2 spring - spring tidal cycles comprising 26 and 24 tides, respectively); and finally eveiy 2 weeks at spring low tide, over 1 calendar year (13-17 profile lines survej'ed and sampled for sediment over 3.25 - 4.251an). In order to further our understanding of gravel beaches, sediment data needs to, be collected at a resolution similar to that of the hydrodynamics. Innovative automatic sediment sizing techniques based on digital images of sediments were therefore developed, and software written, to allow the collection and analysis of high-resolution sediment data. The gi-avel beach step and berm are accretionaiy features, tidally modulated, and evolve under different time scales. A new technique to determine bed mobility from the nearshore, using underwater ^adeo cameras, was devised. Nearsliore sediment transport was suggested as being related to sub-incident wave frequencies. No aspect of morphological change could be found to havea statistically significant association with sedimentological change, but dimensional-reduction techniques did satisfactorily detect association. The lack of co-variance and obvious patterns is stochastic noise, not • parameterisation. Over one year, the barrier underwent asymmetrical rotation over one year, highlighting the importance of alongshore sediment transport processes on this supposedly 'swash aligned' beach. A statistical model based on the log-hj'perbolic distribution of sinface particle sizes was found to be a reasonable predictor of mean net sedimentation over individual tides. Its complicated parameter space could possibly map'onto a simpler plane based on traditional moments. Sediment trend vector models based on sorting alone out-performed a traditional approach. Moments of a surface grain-size'distribution appear to be inappropriate to characterise sedimentological change at time-scales gi-eater than a semi-diurnal tidal cycle. Sub-surface sampling on the intertidal zone on diurnal and semi-lunar time-scales is useful in assessing the dynamics of the step, itself an important mechanism for onshore and offshore net volumetric transport.School of Geograph

Alluvial Substrate Mapping by Automated Texture Segmentation of Recreational-Grade Side Scan Sonar Imagery

Side scan sonar in low-cost ‘fishfinder’ systems has become popular in aquatic ecology and sedimentology for imaging submerged riverbed sediment at coverages and resolutions sufficient to relate bed texture to grain-size. Traditional methods to map bed texture (i.e. physical samples) are relatively high-cost and low spatial coverage compared to sonar, which can continuously image several kilometers of channel in a few hours. Towards a goal of automating the classification of bed habitat features, we investigate relationships between substrates and statistical descriptors of bed textures in side scan sonar echograms of alluvial deposits. We develop a method for automated segmentation of bed textures into between two to five grain-size classes. Second-order texture statistics are used in conjunction with a Gaussian Mixture Model to classify the heterogeneous bed into small homogeneous patches of sand, gravel, and boulders with an average accuracy of 80%, 49%, and 61%, respectively. Reach-averaged proportions of these sediment types were within 3% compared to similar maps derived from multibeam sonar

Automated Riverbed Sediment Classification Using Low-Cost Sidescan Sonar

The use of low-cost, low-profile, and highly portable sidescan sonar is on the ascendancy for imaging shallow riverine benthic sediments. A new automated, spatially explicit, and physically-based method for calculating lengthscales of bed texture elements in sidescan echograms (a 2D plot of acoustic intensity as a function of slant range and distance) is suggested. It uses spectral analysis based on the wavelet transform of short sequences of echograms. The recursive application of the transform over small overlapping windows of the echogram provides a robust measure of lengthscales of alternating patterns of strong and weak echoes. This textural lengthscale is not a direct measure of grain size. Rather, it is a statistical representation that integrates over many attributes of bed texture, of which grain size is the most important. The technique is a physically-based means to identify regions of texture within a sidescan echogram, and could provide a basis for objective, automated riverbed sediment classification. Results are evaluated using data from two contrasting riverbed environments: those of the Colorado River in Grand Canyon, Arizona, and the West Branch of the Penobscot River, Maine

Storm event to seasonal evolution of nearshore bathymetry derived from shore-based video imagery

Coastal evolution occurs on a wide range of time-scales, from storms, seasonal and inter-annual time-scales to longer-term adaptation to changing environmental conditions. Measuring campaigns typically either measure morphological evolution on a short-time scale (days) with high frequency (hourly) or long-time scales (years) but intermittently (monthly). This leaves an important observational gap that limits morphological variability assessments. Traditional echo sounding measurements on this long time-scale and high-frequency sampling require a significant financial injection. Shore-based video systems with high spatiotemporal resolution can bridge this gap. For the first time, hourly Kalman filtered video-derived bathymetries covering 1.5 years of morphological evolution with an hourly resolution obtained at Porhtowan, UK are presented. Here, the long-term hourly dataset is used and aims to show its added value for, and provide an in-depth, morphological analyses with unprecedented temporal resolution. The time-frame includes calm and extreme (storm) wave conditions in a macro-tidal environment. The video-derived bathymetries allow hourly beach state classification while before this was not possible due to the dependence on foam patterns of wave breaking (e.g., saturation during storms). The study period covers extreme storm erosion during the most energetic winter season in 60 years (2013-2014). Recovery of the beach takes place on several time-scales: (1) an immediate initial recovery after the storm season (first 2 months), (2) limited recovery during low energetic summer conditions and (3) accelerated recovery as the wave conditions picked up in the subsequent fallunder wave conditions that are typically erosive. The video-derived bathymetries are shown to be effective in determining bar-positions, outer-bar three-dimensionality and volume analyses with an unprecedented hourly temporal resolution

Clinical application of autologous technetium-99m-labelled eosinophils to detect focal eosinophilic inflammation in the lung.

This is the final version of the article. It first appeared from the BMJ Group via http://dx.doi.org/10.1136/thoraxjnl-2015-207156The detection of focal eosinophilic inflammation by non-invasive means may aid the diagnosis and follow-up of a variety of pulmonary pathologies. All current methods of detection involve invasive sampling, which may be contraindicated or too high-risk to be performed safely. The use of injected autologous technetium-99m (Tc-99m)-labelled eosinophils coupled to single-photon emission computed tomography (SPECT) has been demonstrated to localise eosinophilic inflammation in the lungs of a patient with antineutrophil cytoplasmic antibody-positive vasculitis. Here, we report on the utility of this technique to detect active eosinophilic inflammation in a patient with focal lung inflammation where a biopsy was contraindicated.The authors thank all the staff at the Department of Nuclear Medicine at Addenbrooke’s Hospital and the Wellcome Trust Clinical Research Facility, Cambridge; Cambridge Biomedical Research Centre Core Biochemistry Assay Laboratory; and the National Institute for Health Research, through the Comprehensive Clinical Research Network. This work was supported by Asthma-UK [08/11], the Medical Research Council [grant number MR/J00345X/1], the Wellcome Trust [grant number 098351/Z/12/Z], and Cambridge NIHR Biomedical Research Centre. Written informed consent was obtained in accordance with the Declaration of Helsinki. The study was approved by Cambridgeshire Research Ethics Committee (09/H0308/119) and the Administration of Radioactive Substances Advisory Committee of the United Kingdom (83/3130/25000)

Comprehensive study of swash-zone hydrodynamics and sediment transport

A comprehensive study of swash-zone sediment transport was conducted on a macro-tidal beach in Perranporth, UK. The unique study is the first to simultaneously measure suspended sediment and sheet flow sediment concentrations and near bed velocity on a natural beach. Data collected during the study will be used to address the importance of sheet flow processes on swash zone sediment transport and morphology, the variability in the near bed velocity profile and the importance of alongshore and vertical flows, cross-shore advection of turbulence and the inference of swash zone forcing and momentum transfer from remotely sensed data

Photometric Observations of Three High Mass X-Ray Binaries and a Search for Variations Induced by Orbital Motion

We searched for long period variation in V-band, Ic-band and RXTE X-ray light curves of the High Mass X-ray Binaries (HMXBs) LS 1698 / RX J1037.5-5647, HD 110432 / 1H 1249-637 and HD 161103 / RX J1744.7-2713 in an attempt to discover orbitally induced variation. Data were obtained primarily from the ASAS database and were supplemented by shorter term observations made with the 24- and 40-inch ANU telescopes and one of the robotic PROMPT telescopes. Fourier periodograms suggested the existence of long period variation in the V-band light curves of all three HMXBs, however folding the data at those periods did not reveal convincing periodic variation. At this point we cannot rule out the existence of long term V-band variation for these three sources and hints of longer term variation may be seen in the higher precision PROMPT data. Long term V-band observations, on the order of several years, taken at a frequency of at least once per week and with a precision of 0.01 mag, therefore still have a chance of revealing long term variation in these three HMXBs.Comment: Accepted, RAA, May, 201