Quad Meshing

Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi-regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this State of the Art Report, we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrization, and remeshing

research policy dialogues in italy

Italy is usually characterised by political scientists as a country with a high degree of penetration of party politics over public administration and civil society. Experts are often considered either marginal or controversial figures. Especially when involved in policymaking, experts tend to be linked to specific political parties, and claims of impartiality are met with suspicion. This explains why in Italy it took a rather long time before a true dialogue between academia and policymakers developed, while once a formal dialogue structure was set in place, in the late 1990s, it did not last very long. Since then, the use of expert knowledge by policy makers has been primarily of a symbolic nature, either of a legitimising or of a substantiating kind, or it has not been used at all. For instrumental utilisation to occur, responsible and interested policymakers and public officials must be in place, a condition that seems to have been met in only few specific cases

Non-formal spaces of socio-cultural accompaniment: Responding to young unaccompanied refugees – reflections from the Partispace project.

Drawing on research in progress in the Partispace project we make a case for the recognition of the importance of non-formal spaces in response to young refugees across three different national contexts: Frankfurt in Germany; Gothenburg in Sweden; and Manchester in the UK. It is argued that recognition of local regulation and national controls of immigration which support climates of hostility makes it important to recognise and affirm the significance of non-formal spaces and ‘small spaces close to home’ which are often developed in the ‘third space’ of civil society and arise from the impulses driven by the solidarity of volunteers. In these contexts it is important that practices of hospitality can develop which symbolically reconstitute refugees as hosts and subjects of a democratic conversation, without which there is no possible administrative solution to the refugee crisis. It is essential that educational spaces such as schools, colleges and universities forge strong bonds with such emergent spaces

Irregular Migration Theories

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Distillation of News Flow intoAnalysis of Stock Reactions

News carry information of market moves. The gargantuan plethora of opinions, facts and tweets on financial business owners the opportunity to test and analyze the influence of such text sources on future directions of stocks. It also creates though the necessity to distill via statistical technology the informative elements of this prodigious and indeed colossal data source. Using mixed text sources from professional platforms, blog fora and stock message boards we distill via different lexica sentiment variables. These are employed for an analysis of stock reactions: volatility, volume and returns. An increased (negative) sentiment will in uence volatility as well as volume. This influuence is contingent on the lexical projection and different across GICS sectors. Based on review articles on 100 S&P 500 constituents for the period of October 20, 2009 to October 13, 2014 we project into BL, MPQA, LM lexica and use the distilled sentiment variables to forecast individual stock indicators in a panel context. Exploiting different lexical projections, and using different stock reaction indicators we aim at answering the following research questions: (i) Are the lexica consistent in their analytic ability to produce stock reaction indicators, including volatility, detrended log trading volume and return? (ii) To which degree is there an asymmetric response given the sentiment scales (positive v.s. negative)? (iii) Are the news of high attention firms diffusing faster and result in more timely and effcient stock reaction? (iv) Is there a sector specific reaction from the distilled sentiment measures? We find there is significant incremental information in the distilled news ow. The three lexica though are not consistent in their analytic ability. Based on confidence bands an asymmetric, attention-specific and sector-specific response of stock reactions is diagnosed

Geodesic Distance Computation via Virtual Source Propagation

We present a highly practical, efficient, and versatile approach for computing approximate geodesic distances. The method is designed to operate on triangle meshes and a set of point sources on the surface. We also show extensions for all kinds of geometric input including inconsistent triangle soups and point clouds, as well as other source types, such as lines. The algorithm is based on the propagation of virtual sources and hence easy to implement. We extensively evaluate our method on about 10 000 meshes taken from the Thingi10k and the Tet Meshing in the Wild data sets. Our approach clearly outperforms previous approximate methods in terms of runtime efficiency and accuracy. Through careful implementation and cache optimization, we achieve runtimes comparable to other elementary mesh operations (e.g. smoothing, curvature estimation) such that geodesic distances become a “first-class citizen” in the toolbox of geometric operations. Our method can be parallelized and we observe up to 6× speed-up on the CPU and 20× on the GPU. We present a number of mesh processing tasks easily implemented on the basis of fast geodesic distances. The source code of our method is provided as a C++ library under the MIT license

Cost Minimizing Local Anisotropic Quad Mesh Refinement

Abstract Quad meshes as a surface representation have many conceptual advantages over triangle meshes. Their edges can naturally be aligned to principal curvatures of the underlying surface and they have the flexibility to create strongly anisotropic cells without causing excessively small inner angles. While in recent years a lot of progress has been made towards generating high quality uniform quad meshes for arbitrary shapes, their adaptive and anisotropic refinement remains difficult since a single edge split might propagate across the entire surface in order to maintain consistency. In this paper we present a novel refinement technique which finds the optimal trade-off between number of resulting elements and inserted singularities according to a user prescribed weighting. Our algorithm takes as input a quad mesh with those edges tagged that are prescribed to be refined. It then formulates a binary optimization problem that minimizes the number of additional edges which need to be split in order to maintain consistency. Valence 3 and 5 singularities have to be introduced in the transition region between refined and unrefined regions of the mesh. The optimization hence computes the optimal trade-off and places singularities strategically in order to minimize the number of consistency splits — or avoids singularities where this causes only a small number of additional splits. When applying the refinement scheme iteratively, we extend our binary optimization formulation such that previous splits can be undone if this prevents degenerate cells with small inner angles that otherwise might occur in anisotropic regions or in the vicinity of singularities. We demonstrate on a number of challenging examples that the algorithm performs well in practice