Measuring and modelling of cross-shore sediment transport and profile evolution on natural beaches

Cross-shore sediment transport is the dominant process causing beach profile evolution. The ability to model cross-shore sediment transport allows prediction of the future beach state be made. Due to a balance between opposing mechanisms, cross-shore sediment transport is difficult to predict. One route to make these predictions is with the development of measurement based parameterisation. This study builds on previousp arameterisationtsh at have relatedc ross-shorev elocity moment (predictorso f suspendeds edimentt ransporta ccordingt o the energeticsa pproacht o sediment transport)t o normalisedd epth( a proxy of cross-shorep osition),t o presenta new shapef unction parameterisationT. he presentp arameterisatiohna s beend evelopedf rom field measurementosf depth-integratedcr oss-shores uspendeds edimentt ransportm easuredd uring a month long field campaigna t SennenC ove, Cornwall, UK. This parameterisationis an improvemento f the previouss hapef unction parameterisationin three key areas;i ) removest he dependencyo n the energetics approach, and so includes all transport mechanisms, ii) incident energy (parameteriseda s breakpointd epth- hb) is considereda, nd so allows this shapef unction to be usedu nder a wide rangeo f energyc onditions,i ii) the swashz one processesa re consideredin detail. The new shapef unction parameterisationis the sum of four components hapef unctions that represenmt eana nd oscillatoryt ransporti n the surf- and shoalingz onea nd on- and offshore transporti n the swash-zoneA. s eachc omponents hapef unction respondsin dividually to energy level, the net-transport shape function responds to varying conditions. Under high-energy conditions the shape function predicts onshore transport in the shoaling zone, offshore transport in the surf zone and onshore transport in the inner swash zone, while under low energy the shape function predicts all onshore transport with a peak outside the breakpoint and in the inner surf-zone. The shapef unction is implementedin a simple heuristicp rofile evolutionm odel that allows the examination of beach behaviour of under varying conditions to be examined over long (decadal) time-scalesP. reliminaryr esultss how that the shapef unction model is able to replicateo nshore and offshoreb ar migration,b ar developmenat nd bar degenerationo ver timescalen ot previously modelled.F uture work will use this model to investigatet he responseto subtletiesi n driving conditions,s ucha s the varying effect of seasonalityc omparedto randoms torms.the Natural Environnient Research Counci

Report on AtlantOS fitness to MSFD needs

Assessment of impact of AtlantOS on North West Shelf state reanalyses

Reanalysis for MSFD

This report gives a brief summary of progress to date in Task 8.6 of AtlantOS. At the time of writing (September 2017) results are being written up in a paper for the peer-reviewed literature (Tinker et al., in prep.), expected to be submitted in Autumn 2017. To maintain the confidentiality of the peer review process only a brief summary of the results of the paper are presented here. The paper will be linked to this deliverable report as soon as it is published. In the mean time access to the paper while under review may be requested from the lead authors of this report at [email protected] and [email protected]

Validation of an ensemble modelling system for climate projections for the northwest European shelf seas

The aim of this study was to evaluate the performance of a modelling system used to represent the northwest European shelf seas. Variants of the coupled atmosphere–ocean global climate model, HadCM3, were run under conditions of historically varying concentrations of greenhouse gases and other radiatively active constituents. The atmospheric simulation for the shelf sea region and its surrounds was downscaled to finer spatial scales using a regional climate model (HadRM3); these simulations were then used to drive a river routing scheme (TRIP). Together, these provide the atmospheric, oceanic and riverine boundary conditions to drive the shelf seas model POLCOMS. Additionally, a shelf seas simulation was driven by the ERA-40 reanalysis in place of HadCM3. We compared the modelling systems output against a sea surface temperature satellite analysis product, a quality controlled ocean profile dataset and values of volume transport through particular ocean sections from the literature. In addition to assessing model drift with a pre-industrial control simulation the modelling system was evaluated against observations and the reanalysis driven simulation. We concluded that the modelling system provided an excellent (good) representation of the spatial patterns of temperature (salinity). It provided a good representation of the mean temperature climate, and a sufficient representation of the mean salinity and water column structure climate. The representation of the interannual variability was sufficient, while the overall shelf-wide circulation was qualitatively good. From this wide range of metrics we judged the modelling system fit for the purpose of providing centennial climate projections for the northwest European shelf seas

Optimal management of posterior cruciate ligament injuries: current perspectives

Background: The optimal management of posterior cruciate ligament (PCL) injuries is debated by orthopedic surgeons. A natural history study (NHS) of acute, isolated PCL tears in patients with a mean follow-up of 14.3 years was previously published. The purpose of this study was to compare and contrast the results of the NHS study with those of other studies with similar follow-up time after operative and nonoperative management of isolated PCL tears. Material and methods: With reviewing the literature, six operative management and six nonoperative management studies were found for treating isolated PCL injuries. We analyzed the subjective and objective outcomes of these 12 studies and compared them to the results of the NHS to determine optimal management of PCL injuries. Results: Final follow-up times ranged from a mean of 6.2 to 15 years in the nonoperative studies and 6.3 to 12 years in the operative studies. Side-to-side differences in laxity following surgical management ranged from 1.1 to 7 mm on KT-1000 arthrometer testing and 2.8 to 4.7 mm on Telos stress testing. Tegner scores at final follow-up ranged from 6.6 to 7.7 in nonoperative studies and 5.7 to 7.4 in operative studies. International Knee Documentation Committee scores were 73.4, 82.7, and 84 in nonoperative studies and 65 and 87 in the operative studies. Lysholm scores were 85.2 in the nonoperative study and ranged from 81 to 92.1 in operative studies. Osteoarthritis was reported with ranges from 17% to 88% in nonoperative studies and 13.3% to 63.6% in operative studies. Conclusion: We found that the subjective and objective results in the NHS compare favorably to those of outcomes for PCL reconstruction. Unless a technique is found that can completely restore knee stability, it is unlikely that simply reducing posterior laxity will improve outcomes or prevent the development of osteoarthritis

A Performance Comparison of a Technical Trading System with ARIMA and VAR Models for Soybean Complex Prices

Both technical trading systems and standard economic time series models are based upon the assumption that current market prices are not independent of past market behavior. This study examines the relative performance of a Channel (CHL) technical trading system with an Autoregressive Integrated Moving Average (ARIMA) model and a Vector Autoregressive (VAR) model in forecasting soybean, soybean meal, and soybean oil prices over the period January 1984-June 1988. ARIMA and VAR models are developed over the time period January 1974-December 1983 and then are used to forecast out-of-sample from January 1984 through June 1988. The CHL trading signals and out-of-sample two month ahead forecasts from the ARIMA and VAR models are used to take positions in the futures markets. The resulting trading returns are evaluated to determine the relative economic performance of the models within the soybean complex. Of these models, the CHL technical trading system exhibits consistent trading returns across the soybean complex. Furthermore, the CHL technical trading system is robust across the two subperiods of the out-of-sample period, one of which is characterized by rising commodity prices and the other by declining commodity prices. These results suggest that in the short run, regularities within a single price series can be used to forecast prices within the soybean complex. Further, technical trading system prove more useful in utilizing such regularities for forecasting than the autoregressive or moving average processes found in either ARIMA or VAR modeling techniques

Non-Gaussian Scatter in Cluster Scaling Relations

We investigate the impact of non-Gaussian scatter in the cluster mass-observable scaling relation on the mass and redshift distribution of clusters detected by wide area surveys. We parameterize non-Gaussian scatter by incorporating the third and forth moments (skewness and kurtosis) into the distribution P(Mobs|M). We demonstrate that for low scatter mass proxies the higher order moments do not significantly affect the observed cluster mass and redshift distributions. However, for high scatter mass indicators it is necessary for the survey limiting mass threshold to be less than 10^14 h^-1 Msol to prevent the skewness from having a significant impact on the observed number counts, particularly at high redshift. We also show that an unknown level of non-Gaussianity in the scatter is equivalent to an additional uncertainty on the variance in P(Mobs|M) and thus may limit the constraints that can be placed on the dark energy equation of state parameter w. Furthermore, positive skewness flattens the mass function at the high mass end, and so one must also account for skewness in P(Mobs|M) when using the shape of the mass function to constrain cluster scaling-relations.Comment: 6 Pages, 3 Figures, to be submitted to ApJ Letter

Electric Sail Tether Deployment System for CubeSats

An Electric Sail (E-Sail) propulsion system consists of long, thin tethers - positively-charged wires extending radially and symmetrically outward from a spacecraft. Tethers must be biased using a high-voltage power supply to ensure that the solar wind produces thrust. While the E-Sail concept shows great promise for flying heliopause missions with higher characteristic acceleration than solar sails, there are significant technical challenges related to deploying and controlling multiple tethers. A typical full-scale design involves a hub and spoke arrangement of 10 to 100 tethers, each 20 km long. In the last 20 years, there have been multiple space mission failures due to tether deployment and control issues, and most configurations involved a single tether. This paper describes an effort to develop and test a simple yet robust single-tether deployment system for a two-6U CubeSat configuration. The project included the following: a) Tether dynamic modeling/simulation b) E-Sail single-tether prototype development and testing c) Space environmental effects testing to identify best materials for further development. These three areas of investigation were needed to provide technical rationale for an E-Sail flight demonstration mission that is expected to be proposed for the 2022 time frame. The project team used an agile engineering approach in which E-Sail single-tether prototype designs were iteratively developed and tested to solve problems and identify design improvements. The agile approach was ideal for this low Technology Readiness Level (TRL) project because tether deployer development involved many unknowns in prototype development that could only be discovered through iterative cycles of construction and testing. Extensive modeling and simulation were accomplished for three types of tether deployment: a) Stage 1: propulsive separation with one 6U fixed b) Stage 2: propulsive spin-up with one 6U fixed c) Stage 3: propulsive spin-up with both 6Us free Simulation results were valuable for understanding the propulsive and braking forces needed for controlled tether deployment. This paper describes the evolution, insights, and test/ performance data related to the resultant single-tether two-6U E-Sail test article which has been demonstrated in a test laboratory. The development effort suggests near-term work needed to achieve a useful flight demonstration, and provides ideas for how multiple-tether deployment systems might evolve going forward. A planned next-generation E-Sail prototype will include autonomous propulsive tether deployment while monitoring tether tension, location on the floor, distance between tether ends, acceleration, velocity, and propellant used

Climate change accelerates range expansion of the invasive non-native species, the Pacific oyster, Crassostrea gigas.

Invasive non-native species and global warming are two of the greatest components of global ecosystem change. The Pacific oyster, Crassostrea gigas, is the world most cultivated shellfish and was introduced throughout the Northwest European Shelf (NWES) under the premise it could not complete its life cycle. Recent warming trends have changed this and wild populations can be found as far north as Nordic Scandinavia. Under the RCP8.5 concentration pathway, we predict that the majority of NWES coastline will be within C. gigas’s thermal recruitment niche by 2100. Given the widespread occurrence of current naturalized C. gigas populations, its large larval dispersal potential and a lack of feasible management solutions, C. gigas will likely undergo a considerable range expansion this century. The time taken to reach maturity is predicted to decrease by up to 60 days, which may lead to precocious spawning events, facilitating expansion further. Crassostrea gigas can form extensive reefs completely transforming native systems. This may compromise native biodiversity, protected habitats, and commercial species. However, naturalization can also deliver a number of beneficial ecosystem goods and services to human society. Whether naturalization is deemed positive or negative will depend on biogeographic context, the perceptions of stakeholders, and the wider management priorities