Nonlinear Dynamics of Composite Fermions in Nanostructures

We outline a theory describing the quasi-classical dynamics of composite fermions in the fractional quantum Hall regime in the potentials of arbitrary nanostructures. By an appropriate parametrization of time we show that their trajectories are independent of their mass and dispersion. This allows to study the dynamics in terms of an effective Hamiltonian although the actual dispersion is as yet unknown. The applicability of the theory is verified in the case of antidot arrays where it explains details of magnetoresistance measurements and thus confirms the existence of these quasiparticles.Comment: submitted to Europhys. Lett., 4 pages, postscrip

Information Ethics Education for a Multicultural World

How can we prepare information systems students to face the ethical challenges of a globalized world? This paper describes a three-step approach for addressing these challenges. First, we have designed undergraduate and graduate information ethics courses that expand the range of learning of ethical theories beyond the traditional Western canon to include a wide spectrum of non-Western and feminist theories. Second, we have designed interactive cases for this course that adopt a collaborative learning approach where students work together in small groups by playing different roles that make interdependent decisions. Third, we deliver these cases via an educational simulation, making the approach scalable and transferable to other institutions across the country and around the world. The data for this study includes textual answers from end-of-semester questionnaires completed by 101 undergraduate and graduate students during four information ethics courses that included use of the simulation. Data was analyzed using thematic analysis, focusing on the multicultural and global dimensions of student learning. Five themes emerged from data collected in the four courses: Learning about a Diverse Range of Ethical Theories; Learning about how Ethical Theories are Related to Culture and Values; Relating International and Multicultural Dimensions to Understanding Oneself; Relating International and Multicultural Dimensions to Understanding Others; and Understanding the Role of Ethics and Culture in Information Systems Design and Use. Based on these results, the three-step approach developed in this study can be implemented across the country and around the world to ensure that students are prepared for the ethical challenges of a globalized world

Devil's Staircase in Magnetoresistance of a Periodic Array of Scatterers

The nonlinear response to an external electric field is studied for classical non-interacting charged particles under the influence of a uniform magnetic field, a periodic potential, and an effective friction force. We find numerical and analytical evidence that the ratio of transversal to longitudinal resistance forms a Devil's staircase. The staircase is attributed to the dynamical phenomenon of mode-locking.Comment: two-column 4 pages, 5 figure

Cost-effective learning for classifying human values

Prior work has found that classifier accuracy can be improved early in the process by having each annotator label different documents, but that later in the process it becomes better to rely on a more expensive multiple-annotation process in which annotators subsequently meet to adjudicate their differences. This paper reports on a study with a large number of classification tasks, finding that the relative advantage of adjudicated annotations varies not just with training data quantity, but also with annotator agreement, class imbalance, and perceived task difficulty

Understanding IT Innovations Through Computational Analysis of Discourse

How do Information Technology (IT) innovation concepts emerge, coexist, evolve, and relate to each other? To address this question, we theorize that innovation concepts are interrelated in an idea network, where they can be likened to species in a competitive and symbiotic resource space. Communities of organizations and people interested in the innovations produce discourse that both reflects and enables the flows of attention among innovations. From this ecological perspective, we apply discourse analysis to innovation research and propose computational approach to scale up the analysis. Specifically, we employed Kullback-Leibler divergence to compare the linguistic patterns of 48 IT innovations reported in InformationWeek and Computerworld over a decade. Using multidimensional scaling, we found that similar innovations demonstrated similar discourses. The results demonstrate the validity, scalability, and utility of computational discourse analysis for practitioners and scholars to understand the socio-technical dynamics in the IT innovation ecosystem

Free particle scattering off two oscillating disks

We investigate the two-dimensional classical dynamics of the scattering of point particles by two periodically oscillating disks. The dynamics exhibits regular and chaotic scattering properties, as a function of the initial conditions and parameter values of the system. The energy is not conserved since the particles can gain and loose energy from the collisions with the disks. We find that for incident particles whose velocity is on the order of the oscillating disk velocity, the energy of the exiting particles displays non-monotonic gaps of allowed energies, and the distribution of exiting particle velocities shows significant fluctuations in the low energy regime. We also considered the case when the initial velocity distribution is Gaussian, and found that for high energies the exit velocity distribution is Gaussian with the same mean and variance. When the initial particle velocities are in the irregular regime the exit velocity distribution is Gaussian but with a smaller mean and variance. The latter result can be understood as an example of stochastic cooling. In the intermediate regime the exit velocity distribution differs significantly from Gaussian. A comparison of the results presented in this paper to previous chaotic static scattering problems is also discussed.Comment: 9 doble sided pages 13 Postscript figures, REVTEX style. To appear in Phys. Rev.

Perfectly Translating Lattices on a Cylinder

We perform molecular dynamics simulations on an interacting electron gas confined to a cylindrical surface and subject to a radial magnetic field and the field of the positive background. In order to study the system at lowest energy states that still carry a current, initial configurations are obtained by a special quenching procedure. We observe the formation of a steady state in which the entire electron-lattice cycles with a common uniform velocity. Certain runs show an intermediate instability leading to lattice rearrangements. A Hall resistance can be defined and depends linearly on the magnetic field with an anomalous coefficient reflecting the manybody contributions peculiar to two dimensions.Comment: 13 pages, 5 figure