Reversible to Irreversible Flow Transition in Periodically Driven Vortices

We show that periodically driven superconducting vortices in the presence of quenched disorder exhibit a transition from reversible to irreversible flow under increasing vortex density or cycle period. This type of behavior has recently been observed for periodically sheared colloidal suspensions and we demonstrate that driven vortex systems exhibit remarkably similar behavior. We also provide evidence that the onset of irreversible behavior is a dynamical phase transition.Comment: 4 pages, 4 postscript figures. Version to appear in Physical Review Letter

Demystifying The Role Of Culture In Coaching Relationships

This capstone examines the role of culture and cross-cultural competence in coaching relationships. The business world is becoming increasingly globalized, with workers interacting across geographic and linguistic and cultural differences. In addition, many American companies are actively diversifying their leadership teams, which increases cultural differences in C-suites and beyond. These individuals need to develop significant cross-cultural competence in order to effectively engage with one another. Coaches working with these diverse and globalized companies need to both develop their own cultural competency and grow their expertise in coaching others to develop cultural competency. In this study I engaged in intensive coaching with two Asian–American women, reflected on each of the coaching sessions, and analyzed the content of the sessions as well as my reflections. My findings include the following: Aspects of a coach\u27s culture influence how they perceive and engage with a client; aspects of a client\u27s culture influence how they perceive and engage with a coach; clients and coaches make assumptions about each other based on a number of factors, including race; and the identities of coaches and clients are expressed and negotiated through stories. This capstone raises many interesting questions for future examination, including what strategies can be deployed beyond awareness of cultural differences and building more inclusive coaching models

Reaching the Rural Audience

Measuring radio\u27s effectiveness at reaching rural audiences has been the subject of hundreds of studies over the past 50 years

CONTEST : a Controllable Test Matrix Toolbox for MATLAB

Large, sparse networks that describe complex interactions are a common feature across a number of disciplines, giving rise to many challenging matrix computational tasks. Several random graph models have been proposed that capture key properties of real-life networks. These models provide realistic, parametrized matrices for testing linear system and eigenvalue solvers. CONTEST (CONtrollable TEST matrices) is a random network toolbox for MATLAB that implements nine models. The models produce unweighted directed or undirected graphs; that is, symmetric or unsymmetric matrices with elements equal to zero or one. They have one or more parameters that affect features such as sparsity and characteristic pathlength and all can be of arbitrary dimension. Utility functions are supplied for rewiring, adding extra shortcuts and subsampling in order to create further classes of networks. Other utilities convert the adjacency matrices into real-valued coefficient matrices for naturally arising computational tasks that reduce to sparse linear system and eigenvalue problems

Researching Social Networks in Action

Many communities across Canada today are challenged by conditions that approach social and economic disintegration. As agencies of the state cut back their financial support of welfare services, citizens are faced with both increasing levels of stress and fewer forms of relief provided by established institutions. For researchers, the challenges of a shrinking resource base are compounded by ongoing epistemological and methodological controversies within social science. The recent emergence of a postmodern critique of traditional social-scientific methodology arises from some profound reorientations in the philosophy and the social context of the social sciences, reorientations that are reflective of fundamental economic and political transformations. This paper describes the action-research program we have designed and implemented in response to these challenges. Starting with a small core of citizens from the community of Hespeler, Ontario, we have been using ethnographic methods to trace the networks of which these people are part and the ways in which those networks are constructed and maintained. The insights gained from this inquiry process are being used, in turn, to develop methods of strengthening local support structures, through collaborative processes of research and action. Such strengthening forms of interaction are not only desirable on their own terms. They also provide a model for restructuring relationships among research participants, and among forms of knowledge and being

Improved large-mode area endlessly single-mode photonic crystal fibers

We numerically study the possibilities for improved large-mode area endlessly single mode photonic crystal fibers for use in high-power delivery applications. By carefully choosing the optimal hole diameter we find that a triangular core formed by three missing neighboring air holes considerably improves the mode area and loss properties compared to the case with a core formed by one missing air hole. In a realized fiber we demonstrate an enhancement of the mode area by ~30 % without a corresponding increase in the attenuation.Comment: 3 pages including 3 eps-figures. Accepted for Optics Letter