Modelling storm response on gravel beaches using XBeach-G

EPRSC New Understanding and Prediction of Storm Impacts on Gravel beaches (NUPSIG; EP/H040056/1) and Adaptation and Resilience of Coastal Energy Supply (ARCEoS; EP/IO35390/1). The full text is under embargo until 01.12.15. Published by ICE Publishin

Morphodynamic variability of high-energy macrotidal beaches, Cornwall, UK

The full text is under embargo until 01.04.16

Apparatus comprising an optical gain device, and method of producing the device

Disclosed is apparatus comprising an optically pumped optical gain device that comprises a rare earth (RE)-doped planar waveguide with non-uniform dopant distribution in the core of the waveguide. The RE ions are advantageously distributed such that the ions are concentrated in a core region in which the mode intensity of both signal radiation and pump radiation is relatively high. In preferred embodiments of a single mode planar waveguide according to the invention the RE ions are substantially concentrated in the central core region. A method of making the disclosed apparatus is also disclosed. The method involves implantation of RE ions into the core region.Published versio

The role of antiphase boundaries during ion sputtering and solid phase epitaxy of Si(001)

The Si(001) surface morphology during ion sputtering at elevated temperatures and solid phase epitaxy following ion sputtering at room temperature has been investigated using scanning tunneling microscopy. Two types of antiphase boundaries form on Si(001) surfaces during ion sputtering and solid phase epitaxy. One type of antiphase boundary, the AP2 antiphase boundary, contributes to the surface roughening. AP2 antiphase boundaries are stable up to 973K, and ion sputtering and solid phase epitaxy performed at 973K result in atomically flat Si(001) surfaces.Comment: 16 pages, 4 figures, to be published in Surface Scienc

Beyond Relevant Conduct--The Federal Sentencing Commission\u27s (In)Discretion: How U.S.S.G. Section 2G2.2(B)(4) Illustrates the Future of the Sentencing Guidelines

This Note explores the aftermath of the creation of the Federal Sentencing Guidelines and the choice to include relevant conduct as a sentencing criteria. It argues that peculiar, unintended consequences have largely been the result of this attempted reform. The inclusion of relevant conduct, despite its debatable connection to congressional intent, combined with a statute left over from pre- Guideline sentencing that mandates rampant judicial discretion at sentencing, has allowed the disparity-producing sentencing of old to creep back into the post-Guideline world. This time, however, the wide-ranging discretion to consider virtually any conduct at sentencing is comfortably hidden behind the curtain of agency discretion, making appellate review deferential at best and nonexistent at worst. To illustrate the current state of sentencing affairs, this Note focuses on a specific provision in the Federal Sentencing Guidelines, section 2G2.2(b)(4). Although this provision is a sentencing enhancement and therefore separate from the relevant conduct inquiry undertaken in section 1B1.3, it is a clear indication of how far beyond relevant conduct courts can now go and a warning of the possible future effects on federal criminal sentencing

Ion induced segregation in gold nanostructured thin films on silicon

We report a direct observation of segregation of gold atoms to the near surface regime due to 1.5 MeV Au2+ ion impact on isolated gold nanostructures deposited on silicon. Irradiation at fluences of 6x10^13, 1x10^14 and 5x10^14 ions cm-2 at a high beam flux of 6.3x1012 ions cm-2 s-1 show a maximum transported distance of gold atoms into the silicon substrate to be 60, 45 and 23 nm, respectively. At a lower fluence (6x1013 ions cm-2) transport has been found to be associated with the formation of gold silicide (Au5Si2). At a high fluence value of 5x10^14 ions cm-2, disassociation of gold silicide and out-diffusion lead to segregation of gold to defect - rich surface and interface region.Comment: 10 pages, 2 figure

The extreme 2013/2014 winter storms: Beach recovery along the southwest coast of England

publisher: Elsevier articletitle: The extreme 2013/2014 winter storms: Beach recovery along the southwest coast of England journaltitle: Marine Geology articlelink: http://dx.doi.org/10.1016/j.margeo.2016.10.011 content_type: article copyright: © 2016 The Authors. Published by Elsevier B.V

MORPHOLOGICAL RESPONSE OF HIGH-ENERGY MACROTIDAL BEACHES

Spatial data collected over 3 years is presented to assess the extent of morphological variability under seasonal and storm waves at four high-energy macrotidal beaches. A novel approach is adopted to identify and classify the beach response which is used to assess the relative stability of the system to changes in the dominant forcing conditions. Field measurements and modelling simulations using XBeach provide further support for a storm dominated system exhibiting relative stability. Morphologically the beaches range from dissipative to intermediate and are characterised by low tide bar/rip morphology which plays a key role in the nearshore dynamics and beach safety. Located in the north coast of Cornwall the sites are exposed to high-energy waves that dominate the stability and behaviour of beaches in this region. The growing need for marine renewable energy in the UK has led to the deployment of a Wave Hub on the seabed off the north coast of Cornwall, designed to provide grid connection for wave energy devices (WECs). As a unique development much has been done to address concerns over potential impacts cause by arrays of WECs during its construction and operational lifetime; these predicted impacts include changes in the quality of waves for surfing and effects on the beach dynamics which determines beach safety through the presence of bar/rip features. In this thesis three years of monthly topographic surveys were collected from beaches in the proposed Wave Hub shadow zone to assess their morphodynamic variability. Realtime kinematic (RTK) GPS surveys were undertaken using an all-terrain vehicle to measure the three dimensional (3D) morphology at four beaches (Perranporth, Chapel Porth, Porthtowan and Gwithian) situated along a 23 km stretch of the north Cornish coast. In addition nearshore wave data, in-situ hydrodynamic measurements, local tide gauges and Argus video data allowed detailed analysis of process-response mechanisms for long term (yearly); seasonal (monthly); storm (weekly/daily); and tidal (hourly) morphological behaviour. Of particular interest was the degree to which the beaches displayed bar/rip morphology, characterised by the three dimensionality (3D) of beach response, which determines wave breaking and affects beach safety. Using a combination of measured shoreline variability and empirical beach classification schemes, the response to changes in the wave conditions at each beach have been assessed. The sites exhibited net long term accretion derived from the intertidal beach volume. Throughout the survey period intersite similarity in beach response was observed in response to storm waves, yet coupling between the seasonal wave climate and the beach morphology was not evident at any of the sites, due to the dominance of recovery phases following storm events. The role of increased wave conditions (exceeding Hs=4 m) during sustained storm events (> 50 hrs) led to offshore transport from the beach face to the subtidal bar region. Post-storm recovery was characterised by onshore transport and the development of substantial 3D low tide morphology. Under normal wave conditions (Hs=1.6 m) the dominant 3D features smoothed out as channels in-filled and bars reduced over a period of 2-3 months. This cyclicity was observed on ~3 occasions at the northern sites, while Gwithian remained more stable throughout; reflecting the more sheltered position of the beach. Overall the beaches exhibited a significant storm dominated morphological response cycle, unlike the more familiar winter/summer seasonal response. Nearshore bar behaviour at Perranporth and Porthtowan, assessed using ARGUS images, was dominated by offshore migration (ca.20 m/yr) following closely the net intertidal accretion, while bar shape exhibited changes over monthly periods. Intensive field studies of morphological change, nearshore current flows and surf zone wave conditions were undertaken at Porthtowan during small swell dominated waves and large energetic storm conditions in May and October 2010 respectively. The field data highlighted accretionary response under small swell dominated waves, and strong offshore directed undertow flows (0.5 m/s-1) during erosive energetic conditions (>Hs = 4m) which were then related to the monthly surveys. These results were applied to XBeach model simulations which helped further identify the importance of antecedent morphology and the complexities of intertidal geology in controlling beach response. The study provides the longest continuous record of beach morphology dynamics for macrotidal energetic sites and provides a valuable addition to work in this field. The dominance of storm driven morphological response was clear with highly threedimensional morphology developing under post storm conditions and continued beach evolution driven by the seasonal conditions. Antecedent morphology was found to be a key element of beach response with geological control an additional component. The projected reduction in wave conditions due to the Wave Hub and the natural variability observed indicates the sites are unlikely to shift significantly from their current dynamic state in response to the Wave Hub, and as such the potential impact on nearshore and beach dynamics is minimal

Realization of the welding of individual TiO2 semiconductor nano-objects using a novel 1D Au80Sn20 nanosolder

Individual semiconductor nanowires (NWs) TiO2 were successfully welded together using novel one-dimensional (1D) Au80Sn20 (mass ratio) nanosolders at the nano-scale for the first time. The nanosolders were electrodeposited into nanoporous templates to form a 1D structure, and their morphology, crystal structure, chemistry and elemental electronic states were systematically characterized. Individual Au80Sn20 nanowires were proved to consist of mixed crystal phases, including a Au5Sn phase with a trigonal structure, a AuSn phase with a hexagonal structure and a small SnO2 phase produced the by oxidation of the surface portion. Chemical analysis indicated that the composition was Au80Sn20. The testing of the welding capability by either in situ TEM or in situ SEM by nanomanipulators and infiltration experiment revealed a good wet ability and diffusion ability between the Au80Sn20 nanosolder and the TiO2 nanowire. It is believed that our study contributes to the field a special nanosolder for future nano-scale welding techniques, which also make the bonding of titanium-based semiconductor oxide nanomaterials at the nano-scale a reality