EU Shipping Taxation: The Comparative Position of Greek Shipping

The critical role shipping taxation has played in the structure and evolution of the shipping business over the last century can easily be recognised. Whether connected with the actual initiation of the open registries scheme or as a means to improve competitiveness of traditional flags, shipping taxation attracts the attention of shipping practitioners and policy makers and constitutes an always topical focus of study. Recent years have particularly seen the rise and growth of tonnage tax system as no longer merely an inventive tax format but as a global standard of shipping taxation, which is in operation for 70% of the global ocean-going fleet. An examination of the European Union (EU) shipping taxation policy exhibits particular interest not only due to the fact that a number of significant traditional ship-owning nations are part of the EU – for example, Greece and the UK – but also due to the presence of fairly recently joined countries with a substantial role in international shipping as popular open registries – for example, Cyprus and Malta. The aim of this paper is to investigate the shipping taxation policy of the EU by concentrating on the forms this takes in selected European countries and to examine critically the comparative position of Greek shipping in this context. Maritime Economics & Logistics (2008) 10, 185–207. doi:10.1057/palgrave.mel.9100198

Fractal dimension as a measure of surface roughness of G protein-coupled receptors: implications for structure and function

Protein surface roughness is a structural property associated with ligand-protein and protein-protein binding interfaces. In this work we apply for the first time the concept of surface roughness, expressed as the fractal dimension, to address structure and function of G protein-coupled receptors (GPCRs) which are an important group of drug targets. We calculate the exposure ratio and the fractal dimension for helix-forming residues of the β(2) adrenergic receptor (β(2)AR), a model system in GPCR studies, in different conformational states: in complex with agonist, antagonist and partial inverse agonists. We show that both exposure ratio and roughness exhibit periodicity which results from the helical structure of GPCRs. The pattern of roughness and exposure ratio of a protein patch depends on its environment: the residues most exposed to membrane are in general most rough whereas parts of receptors mediating interhelical contacts in a monomer or protein complex are much smoother. We also find that intracellular ends (TM3, TM5, TM6 and TM7) which are relevant for G protein binding and thus receptor signaling, are exposed but smooth. Mapping the values of residual fractal dimension onto receptor 3D structures makes it possible to conclude that the binding sites of orthosteric ligands as well as of cholesterol are characterized with significantly higher roughness than the average for the whole protein. In summary, our study suggests that identification of specific patterns of roughness could be a novel approach to spot possible binding sites which could serve as original drug targets for GPCRs modulation