Self-similar transport processes in a two-dimensional realization of multiscale magnetic field turbulence

We present the results of a numerical investigation of charged-particle transport across a synthesized magnetic configuration composed of a constant homogeneous background field and a multiscale perturbation component simulating an effect of turbulence on the microscopic particle dynamics. Our main goal is to analyze the dispersion of ideal test particles faced to diverse conditions in the turbulent domain. Depending on the amplitude of the background field and the input test particle velocity, we observe distinct transport regimes ranging from subdiffusion of guiding centers in the limit of Hamiltonian dynamics to random walks on a percolating fractal array and further to nearly diffusive behavior of the mean-square particle displacement versus time. In all cases, we find complex microscopic structure of the particle motion revealing long-time rests and trapping phenomena, sporadically interrupted by the phases of active cross-field propagation reminiscent of Levy-walk statistics. These complex features persist even when the particle dispersion is diffusive. An interpretation of the results obtained is proposed in connection with the fractional kinetics paradigm extending the microscopic properties of transport far beyond the conventional picture of a Brownian random motion. A calculation of the transport exponent for random walks on a fractal lattice is advocated from topological arguments. An intriguing indication of the topological approach is a gap in the transport exponent separating Hamiltonian-like and fractal random walk-like dynamics, supported through the simulation.Comment: 10 pages (including cover page), 7 figures, improved content, accepted for publication in Physica Script

Performance evaluation in the arts:From the margins of accounting to the core of accountability

Due to the policies introduced by many European governments since the rise of New Public Management in the 1990s, performance measurement has become the dominant means of government control of publicly funded organizations. As a result, publicly funded organizations have been increasingly asked to account to external stakeholders based on quantitative performance measures. Inspired by the economic logic of the business sector, such supposedly objective performance measures have been uncritically applied to all public sector organizations, including those whose value and quality are hardly quantifiable, such as arts organizations. Based on a thorough study of relevant literatures and an in-depth case study of a publicly funded opera company, ‘Performance Evaluation in The Arts’ shows that the rules and procedures of accountability imposed by governments are unable to grasp the core value that arts organizations produce for their stakeholders; i.e., their artistic value. Artistic value is co-determined by all those involved in the processes of artistic creation and distribution - staff, audience, press and peers – and is evaluated by the artistic, administrative and technical managers of arts organizations through information that is largely unwritten, mainly qualitative, and often tacit. Before implementing new accountability rules and procedures, governments should seek to understand the nature of the work processes and their evaluation within arts organizations. Only rules and procedures of accountability which mirror the reality of artistic work and, thereby, provide arts organizations with an artistic language to account for their contribution to society, are likely to be relevant to such organizations and their stakeholders

Ursinus College Junior Prom Dance Card, April 21, 1944

This Ursinus College Junior Prom dance card, measuring 7 x 11 centimeters, belonged to Eleanor Snell. The back of the card contains a list of chaperones, class officers, and junior prom committee members. The prom theme was A Spring night with music by Jack Loughead and his Esquires.https://digitalcommons.ursinus.edu/snell_docs/1003/thumbnail.jp