Voting Advice Applications and the Estimation of Party Positions - A Reliable Tool?

Data contained in Voting Advice Applications (VAAs) is not only a prerequisite for the vote recommendations they provide but can also be used for estimating party positions in low‐dimensional spaces. Given that VAAs can be designed differently in terms of their number of items and their measurement level, how much can one trust the party positions obtained from this source? We tackle this question by exploiting relevant variation in a real‐world setting: three VAAs offered at the 2017 Lower Saxony election. Despite substantial design differences, the policy spaces extracted through an inductive scaling approach are highly convergent. Simulated random item removal from the pooled dataset of all three VAAs furthermore suggests that about 40 items yield satisfactory reliability of the party positions. Finally, we find that a priori assigning VAA‐items to ideological dimensions is potentially problematic as the interpretation of resulting party spaces may differ from the ones derived inductively

Xenophobic violence after Brexit: how Britain could learn from Germany’s experience

Germany has experienced a rise in xenophobic attacks since it began to welcome refugees from Syria and elsewhere. Sebastian Jäckle and Pascal D. König have mapped these attacks and drawn some striking conclusions about their causes. They were more common in regions with a strong far-right presence and fewer migrants. One attack also tended to spark others – as did condemnation of xenophobia by national leaders, and Islamist terror. Britain saw a similar spike in xenophobic crime after the referendum. The authors ask whether the UK can learn from Germany’s painful experience

Frequency Dependent Rheology of Vesicular Rhyolite

Frequency dependent rheology of magmas may result from the presence of inclusions (bubbles, crystals) in the melt and/or from viscoelastic behavior of the melt itself. With the addition of deformable inclusions to a melt possessing viscoelastic properties one might expect changes in the relaxation spectrum of the shear stresses of the material (e.g., broadening of the relaxation spectrum) resulting from the viscously deformable geometry of the second phase. We have begun to investigate the effect of bubbles on the frequency dependent rheology of rhyolite melt. The present study deals with the rheology of bubble-free and vesicular rhyolite melts containing spherical voids of 10 and 30 vol %. We used a sinusoidal torsion deformation device. Vesicular rhyolite melts were generated by the melting (at 1 bar) of an Armenian obsidian (Dry Fountain, Erevan, Armenia) and Little Glass Mountain obsidian (California). The real and imaginary parts of shear viscosity and shear modulus have been determined in a frequency range of 0.005–10 Hz and temperature range of 600°–900°C. The relaxed shear viscosities of samples obtained at low frequencies and high temperatures compare well with data previously obtained by parallel plate viscometry. The relaxed shear viscosity of vesicular rhyolites decreases progressively with increasing bubble content. The relaxation spectrum for rhyolite melt without bubbles has an asymmetric form and fits an extended exponent relaxation. The presence of deformable bubbles results in an imaginary component of the shear modulus that becomes more symmetrical and extends into the low-frequency/high-temperature range. The internal friction Q −1 is unaffected in the high-frequency/low-temperature range by the presence of bubbles and depends on the bubble content in the high-temperature/low-frequency range. The present work, in combination with the previous study of Stein and Spera (1992), illustrates that magma viscosity can either increase or decrease with bubble content, depending upon the rate of style of strain during magmatic flow

Frozen capillary waves on glass surfaces: an AFM study

Using atomic force microscopy on silica and float glass surfaces, we give evidence that the roughness of melted glass surfaces can be quantitatively accounted for by frozen capillary waves. In this framework the height spatial correlations are shown to obey a logarithmic scaling law; the identification of this behaviour allows to estimate the ratio $kT\_F/\pi\gamma$ where $k$ is the Boltzmann constant, $\gamma$ the interface tension and $T\_F$ the temperature corresponding to the ``freezing'' of the capillary waves. Variations of interface tension and (to a lesser extent) temperatures of annealing treatments are shown to be directly measurable from a statistical analysis of the roughness spectrum of the glass surfaces

Drei Jahre Anschläge auf Flüchtlinge in Deutschland - welche Faktoren erklären ihre räumliche und zeitliche Verteilung?

Die Bundesrepublik Deutschland erlebte im Jahr 2015, vor allem ab dem letzten Quartal, eine immense Zuwanderung von Flüchtlingen, die bis ins darauffolgende Jahr anhielt. In der Folge kam es zu einem merklichen Anstieg der Anzahl von Anschlägen auf Flüchtlinge, die erst im Jahr 2017 allmählich zurückgingen. Der vorliegende Aufsatz repliziert eine Studie, die das Auftreten von Anschlägen in Deutschland im Jahr 2015 ergründet hat und prüft, ob die relevanten Erklärungsfaktoren auch in den beiden Folgejahren Gültigkeit haben. Die Analyseergebnisse zeigen, dass noch im Jahr 2015 politische, sozioökonomische und demographische Faktoren struktureller Art einen gewissen Erklärungswert für das Vorkommen von Anschlägen aufweisen. In 2016 und 2017 lässt die Erklärungskraft all dieser Variablen jedoch nach und es zeigt sich über das ganze Land verteilt ein deutlich diffuseres Anschlagsmuster. Als robust erweisen sich über den gesamten Zeitraum hinweg hingegen Ansteckungseffekte durch zeitlich wie räumlich nahe vorangehende fremdenfeindliche Ereignisse.In 2015, Germany took in a tremendous number of refugees, especially during the last quarter, and continued to do so well into 2016. A significant rise in the number of attacks against refugees followed these developments which only abated in 2017. This article replicates an analysis which analyzed the occurrence of attacks on refugees in Germany during 2015 and tests whether explanatory factors found relevant in that work are still valid for the two subsequent years. The results show that in 2015, political, socio-economic and demographic structural factors to some extent can explain anti-refugee violence. However, in 2016 and 2017 the explanatory power of these factors diminishes and we observe a notably more diffuse pattern of attacks throughout the entire country. At the same time, a contagion effect based on spatially as well as temporally close xenophobic violence remains robust for the entire period from 2015 to 2017

Dynamic criticality in glass-forming liquids

We propose that the dynamics of supercooled liquids and the formation of glasses can be understood from the existence of a zero temperature dynamical critical point. To support our proposal, we derive from simple physical assumptions a dynamic field theory for supercooled liquids, which we study using the renormalization group (RG). Its long time behaviour is dominated by a zero temperature critical point, which for dimensions d > 2 belongs to the directed percolation universality class. Molecular dynamics simulations confirm the existence of dynamic scaling behaviour consistent with the RG predictions.Comment: 4 pages, 2 figure

Dynamic first-order phase transition in kinetically constrained models of glasses

We show that the dynamics of kinetically constrained models of glass formers takes place at a first-order coexistence line between active and inactive dynamical phases. We prove this by computing the large-deviation functions of suitable space-time observables, such as the number of configuration changes in a trajectory. We present analytic results for dynamic facilitated models in a mean-field approximation, and numerical results for the Fredrickson-Andersen model, the East model, and constrained lattice gases, in various dimensions. This dynamical first-order transition is generic in kinetically constrained models, and we expect it to be present in systems with fully jammed states.Comment: 4.1 pages, 3 figure

Binding between two-component bosons in one dimension

We investigate the ground state of one-dimensional few-atom Bose-Bose mixtures under harmonic confinement throughout the crossover from weak to strong inter-species attraction. The calculations are based on the numerically exact multi-configurational time-dependent Hartree method. For repulsive components we detail the condition for the formation of a molecular Tonks-Girardeau gas in the regime of intermediate inter-species interactions, and the formation of a molecular condensate for stronger coupling. Beyond a critical inter-species attraction, the system collapses to an overall bound state. Different pathways emerge for unequal particle numbers and intra-species interactions. In particular, for mixtures with one attractive component, this species can be viewed as an effective potential dimple in the trap center for the other, repulsive component.Comment: 10 pages, 10 figure

RfX: A Design Study for the Interactive Exploration of a Random Forest to Enhance Testing Procedures for Electrical Engines

Random Forests (RFs) are a machine learning (ML) technique widely used across industries. The interpretation of a given RF usually relies on the analysis of statistical values and is often only possible for data analytics experts. To make RFs accessible to experts with no data analytics background, we present RfX, a Visual Analytics (VA) system for the analysis of a RF's decision-making process. RfX allows to interactively analyse the properties of a forest and to explore and compare multiple trees in a RF. Thus, its users can identify relationships within a RF's feature subspace and detect hidden patterns in the model's underlying data. We contribute a design study in collaboration with an automotive company. A formative evaluation of RFX was carried out with two domain experts and a summative evaluation in the form of a field study with five domain experts. In this context, new hidden patterns such as increased eccentricities in an engine's rotor by observing secondary excitations of its bearings were detected using analyses made with RfX. Rules derived from analyses with the system led to a change in the company's testing procedures for electrical engines, which resulted in 80% reduced testing time for over 30% of all components