Scattertext: a Browser-Based Tool for Visualizing how Corpora Differ

Scattertext is an open source tool for visualizing linguistic variation between document categories in a language-independent way. The tool presents a scatterplot, where each axis corresponds to the rank-frequency a term occurs in a category of documents. Through a tie-breaking strategy, the tool is able to display thousands of visible term-representing points and find space to legibly label hundreds of them. Scattertext also lends itself to a query-based visualization of how the use of terms with similar embeddings differs between document categories, as well as a visualization for comparing the importance scores of bag-of-words features to univariate metrics.Comment: ACL 2017 Demos. 6 pages, 5 figures. See the Githup repo https://github.com/JasonKessler/scattertext for source code and documentatio

Swinging and tumbling of elastic capsules in shear flow

The deformation of an elastic micro-capsule in an infinite shear flow is studied numerically using a spectral method. The shape of the capsule and the hydrodynamic flow field are expanded into smooth basis functions. Analytic expressions for the derivative of the basis functions permit the evaluation of elastic and hydrodynamic stresses and bending forces at specified grid points in the membrane. Compared to methods employing a triangulation scheme, this method has the advantage that the resulting capsule shapes are automatically smooth, and few modes are needed to describe the deformation accurately. Computations are performed for capsules both with spherical and ellipsoidal unstressed reference shape. Results for small deformations of initially spherical capsules coincide with analytic predictions. For initially ellipsoidal capsules, recent approximative theories predict stable oscillations of the tank-treading inclination angle, and a transition to tumbling at low shear rate. Both phenomena have also been observed experimentally. Using our numerical approach we could reproduce both the oscillations and the transition to tumbling. The full phase diagram for varying shear rate and viscosity ratio is explored. While the numerically obtained phase diagram qualitatively agrees with the theory, intermittent behaviour could not be observed within our simulation time. Our results suggest that initial tumbling motion is only transient in this region of the phase diagram.Comment: 20 pages, 7 figure

The London bombings and racial prejudice: evidence from housing and labour markets

This paper investigates the impact of the London bombings on attitudes towards ethnic minorities, examining outcomes in housing and labour markets across London boroughs. We use a difference-in-differences approach, specifying `treated' boroughs as those with the highest concentration of Asian residents. Our results indicate that house prices in treated boroughs fell by approximately 2.3% in the two years after the bombings relative to other boroughs, with sales declining by approximately 5.7%. Furthermore, we present evidence of a rise in the unemployment rate in treated compared to control boroughs, as well as a rise in racial segregation. These results are robust to several `falsification' checks with respect to the definition and timing of treatment

The Theory of Human Capital Revisited: On the Interaction of General and Specific Investments

Human capital theory distinguishes between training in general-usage and firm-specific skills. In his seminal work, Becker (1964) argues that employers will not be willing to invest in general training when labor markets are competitive. However, they are willing to invest in specific training because it cannot be transferred to outside firms. The paper reconsiders Becker’s theory. We show that there exists an incentive complementarity between employersponsored general and specific investments: the possibility to provide specific training leads the employer to invest in general human capital. Conversely, the latter reduces the hold-up problem that arises with respect to the provision of firm-specific training. We also consider the virtues of long-term contracting and discuss some empirical observations that could be explained by the model.human capital formation, general and specific training, hold-up problem.

Diffusive Boundary Layers in the Free-Surface Excitable Medium Spiral

Spiral waves are a ubiquitous feature of the nonequilibrium dynamics of a great variety of excitable systems. In the limit of a large separation in timescale between fast excitation and slow recovery, one can reduce the spiral problem to one involving the motion of a free surface separating the excited and quiescent phases. In this work, we study the free surface problem in the limit of small diffusivity for the slow field variable. Specifically, we show that a previously found spiral solution in the diffusionless limit can be extended to finite diffusivity, without significant alteration. This extension involves the creation of a variety of boundary layers which cure all the undesirable singularities of the aforementioned solution. The implications of our results for the study of spiral stability are briefly discussed.Comment: 6 pages, submitted to PRE Rapid Com

Redistribution, Fiscal Competition, and the Politics of Economic Integration

The paper examines the redistributive consequences of the economic integration of factor markets. We consider two countries that redistribute income among their residents. The social benefits in each country are financed by a source based tax on capital which is democratically chosen by its inhabitants. If either capital or labour is internationally mobile, the countries engage in fiscal competiton, i.e., the partial integration of capital or labour markets is detrimental to the countries' redistributive ability. A move from partial to full integration, however, may alleviate rather than intensify fiscal competition, particularly, if the two countries face sufficiently similar economic and political conditions. In such a situation, increased integration of labour markets will soften the incentives compete for mobile capital. As a result, there is more redistribution in equilibrium and a majority of the population in each country is strictly better off.