Wave effects on the morphodynamic evolution of an offshore sand bank

The origin and morphodynamic evolution of linear sand banks have been widely studied in recent years. Several investigations have been carried out in order to understand the influence of tide-related parameters, bathymetry and Coriolis force on sand bank formation and maintenance. However, the effect of waves on the net flux of sediments over the sand banks has often been neglected on grounds of the short duration of significant wave activity compared to that of tidal cycles. Nevertheless, the interaction between wave activity and tidal currents leads to a high increase of bottom shear stress, especially at the sand bank crests and, as a consequence, to an increase of sand tranport. This paper investigates the effects of wave activity on the morphology and morphodynamics of the Kwinte Bank (Belgian shelf). Numerical simulations were carried out under different wave conditions to assess wave influence on sand bank evolution. Model verification involved analysis and comparison with field data collected during two different periods. The study shows that wave activity is not only responsible for a large increase in sediment transport but also for a change in direction of the net flux of sediments. Moreover, the morphological analysis of several sand banks supports the idea that wave activity might also have an impact on the shape of these sand banks. Wave climate data can be used to study long-term sand bank dynamics

Modelling the effects of sand extraction, on sediment transport due to tides, on the Kwinte Bank

In recent years, the exploitation of marine aggregates is increasing. As an example, on the Belgian continental shelf, one particular sandbank (the Kwinte Bank) is exploited extensively; this has led to the creation of a 5 m deep depression along its central part. In the present contribution, the influence of these bathymetric changes, on erosion and sedimentation patterns are studied, using numerical modelling, in order to obtain an initial impression of the effect of such intense sand extraction on the stability of the sandbank. Different numerical models are utilised. Twodimensional and three-dimensional hydrodynamic models have been used to derive currents, whilst third generation wave models have been used to simulate the waves. Two different models are presented, which calculate the total load sediment transport as a function of the local currents and waves. These models have been used to investigate the erosional and depositional patterns. The use of two different sediment transport models has some advantages, since the results of sediment transport models are still subject to some important uncertainties. The hydrodynamic model results are validated using ADCP current data, confirming the good performance of the models. Likewise the wave models provide good results, comparing their results with data from a buoy. The sediment transport model results were compared to the residual transport patterns, derived from the asymmetry of dunes. The results obtained seem to be in general agreement with these observations. The numerical models are used to simulate the response of the sediment transport to extensive sand extraction from the sandbank. One ‘worst-case’ scenario and two more realistic scenarios were simulated, whilst the effect of these bathymetric changes on sediment transport was studied. The results show that the intense sand extraction does not seem to influence extensively the stability of the sandbank, but that, as a consequence, there is less erosion and deposition. The model results show, for all of the scenarios, a small amount of deposition on the top of the sandbank; this could be an indication of a regeneration mechanism. A trench, created perpendicular to the crest of the sandbank, could be slowly refilled again. The time-scale of this regeneration and the influence of storms remain uncertain. Although the main emphasis of the paper relates to tidal forcing, a brief discussion is included on the influence of wave action, on sediment transport

Ceramic-faience hybrids were used to recycle bronze in North-Western European Iron Age egg-shaped crucibles

We investigated the characteristics of a group of 13 Middle Iron Age egg-shaped crucibles and crucible fragments from Tilburg (The Netherlands). We used a combination of optical and chemical analyses, including hand-held XRF, microCT scanning and 3-D printing polarizing light microscopy and SEM-EDX. The chemical analyses confirmed that the crucibles were used for copper alloy metallurgy. Impressions in the lids of the crucibles turned out to be imprints of copper alloy scrap, including fragments of twisted wire and fibulae. Most remarkable, however, is the large proportion of sheet metal among the scrap.In order to make crucibles from the local, non-refractory clays, a hitherto unknown ceramic-faience hybrid was used: A combination of clay and halophytic plant ash was mixed with silt into a paste, and this was used to construct the crucible. During firing, the flux would promote melting of the clays and probably prevent catastrophic failure of the crucibles. The resulting glassy groundmass – in which silt grains are embedded and partially dissolved – is rich in Al2O3 as well as in Na2O, K2O, CaO, MgO and Fe2O3.It is likely that this technique of crucible manufacture was widespread in Late Prehistory in areas where no refractory clays were available

PPP1R8 (protein phosphatase 1, regulatory (inhibitor) subunit 8)

Review on PPP1R8 (protein phosphatase 1, regulatory (inhibitor) subunit 8), with data on DNA, on the protein encoded, and where the gene is implicated

Observables of interest for the characterisation of Spent Nuclear Fuel

The characterisation of Spent Nuclear Fuel (SNF) in view of intermediate storage and final disposal is discussed. The main observables of interest that need to be determined are the decay heat, neutron and -ray emission spectra. In addition, the inventory of specific nuclides that are important for criticality safety analysis and to verify the fuel history has to be determined. Some of the observables such as the decay heat and neutron and -ray emission rate can be determined by Non-Destructive Analysis (NDA) methods. Unfortunately, this is not always possible especially during routine operation. Hence, a characterisation of SNF will rely on theoretical calculations combined with results of NDA methods. In this work the observables of interest, also referred to as source terms, are discussed based on theoretical calculations starting from fresh UO2 and MOX fuel. The irradiation conditions are representative for PWR. The Serpent code is used to define the nuclides which have an important contribution to the observables. The emphasis is on cooling times between 1 a and 1000 a.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard