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Securitization theory seeks to explain the politics through which (1) the security character of public problems is established, (2) the social commitments resulting from the collective acceptance that a phenomenon is a threat are fixed and (3) the possibility of a particular policy is created. In the last decade, research on securitization has grown significantly. The aim of this article is to evaluate the achievements of securitization theory. First, its main concepts and premises are critically discussed. This article then proceeds to examine the empirical applications of securitization theory to a broad range of issues, as well as the theoretical implications of these studies. Finally, it discusses the main challenges faced by securitization scholars and puts forward strategies to overcome them. This article develops three inter-related arguments. First, notably thanks to empirical studies, securitization theory has significantly developed beyond its initial focus on the speech act. Second, as a result, the distinctiveness of securitization theory currently lies in its capacity to articulate a specific approach to security – influenced by the speech act – with an ‘analytics of government’, which emphasizes practices and processes. Third, securitization theory faces three types of challenges, related, respectively, to theory, method and methodology. The capacity of scholars to overcome those will strongly influence the extent to which securitization theory will be able to make significant contributions to the debates in Security Studies and International Relations in the years to come.

The impinging position of a 511 keV photon onto a continuous scintillator can be obtained from the light distribution measured by a pixelated photodetector such as avalanche photodiode (APD) arrays. This information is extracted using neural networks trained for events with a particular incidence angle. Using a 20 10 10 mm block of lutetium oxyorthosilicate mounted onto a S8550 Hamamatsu APD matrix we achieved an intrinsic resolution of 1.9 mm full-width at half-maximum (FWHM) for perpendicular incident photons and 2.6 mm FWHM at a 40 incidence angle. A possible implementation for tomographic imaging is presented. Index Terms-Depth of interaction (DOI), neural network (NN), positron emission tomorgraphy (PET).

The development of the EU asylum and migration policy is often explained as the result of 'venue-shopping', that is, the move by policy-makers to an EU policy venue in order to avoid national constraints. This article demonstrates that, contrary to what would have been expected on the basis of this widespread view, EU co-operation on asylum matters has actually led to a rise in the legal standards applicable to asylum-seekers and refugees. This outcome can be mainly explained by broader changes that have gradually affected the EU 'system of venues' and have thereby decreased the likelihood of more restrictive measures being adopted in the EU asylum policy venue. This has important implications for the EU governance of asylum and migration in general.