The Path-Integral Approach to Spontaneous Symmetry Breaking

We will investigate two models which exhibit SSB in the canonical approach: the N=1 and N=2 linear sigma model. In both models the Green's functions and the effective potential will be computed in the path-integral approach. We will demonstrate how we get different results than in the canonical approach.Comment: PhD-thesi

Development of a mud transport model for the Scheldt estuary in the framework of LTV

In 2006, a work plan was conceived for the development of a mud transport model for the Scheldt estuary in the framework of LTV (Long Term Vision) (Winterwerp and De Kok, 2006). The purpose of this model is to support managers of the Scheldt estuary with the solution of a number of managerial issues. Also in 2006, the first two phases were initiated. The present report discusses the activities that have been carried out during the first half of 2007, i.e. Further improvement of the hydrodynamic and mud transport model.At a technical level, all model improvements scheduled for 2007 have been implemented. The most important developments are: longer hydrodynamic simulation period (up to one year), more accurate concentration boundary conditions, variable wave effects and biological effects.The hydrodynamic simulation yields realistic values for water levels and salinities, although it is expected that the modelled velocities will be too high. Three actions are identified that can enhance the simulated hydrodynamics:The high fresh water inflow event in the beginning of March can be modelled more accurately by adding more data points in the time series of fresh water inflow to increase the volume of fresh water contained in the peak.The time series of fresh water inflow of the Bathse Spuikanaal has to be added in the modelA different set of boundary conditions could yield better results for water levels.Regarding the mud transport simulations, the following is concluded:A minor shift of two dumping locations near Antwerp much improves the proper modelling of the ETMNew concentration boundary conditions at sea result in more realistic SPM concentrations at seaThe difference between simulations with 5 and 10 horizontal layers is only minorVariable waves temporarily enhance the concentration in the western part of the Western Scheldt during stormsThe biological impact on large-scale SPM concentrations in the Scheldt estuary appears to be minorThe SPM levels appear to be rather sensitive to the volume of harbour situation and dumpin

Working with Nature in Wadden Sea Ports

Wadden Sea ports are situated at the border of the UNESCO World Heritage site Wadden Sea. Because of the protected status of this area, developing new economic activities is not straightforward. However, maintaining and developing port activities is needed to safeguard the economic viability of the Wadden Seasocio-economic region. In this paper we illustrate that sustainable port development is feasible when adopting a Working with Nature approach. This approach facilitates a design in which the proactive utilization and/or provision of ecosystem services serves as part of the engineering solution. We introduce four Working with Nature concepts that can be used in port designs, i.e. 1) optimising dredging strategies, 2) enhancing saltmarsh development, 3) creating estuarine gradients, and 4) optimising flow patterns. Based on theseconcepts, three case studies have been identified and pilot projects initiated. In the Port of Harlingen a pilot project has started in which an optimized dredging strategy is combined with saltmarsh development. Around the Port of Delfzijl an estuarine gradient is combined with the construction of a salt marsh and dredgedsediment is used for dike strengthening. For the Port of Den Helder, a new design is proposed in which the concepts of enhancing salt marsh development, creating estuarine gradients and optimizing flow patterns are combined. Our conclusion is that even in a World Heritage site such as the Wadden Sea, portdevelopment is possible when ecosystem services are used and provided for, and when a Working with Nature concept is put at the heart of the design