Classification and clustering: models, software and applications

We are pleased to present the report on the 30th Fall Meeting of the working group ``Data Analysis and Numerical Classification'' (AG-DANK) of the German Classification Society. The meeting took place at the Weierstrass Institute for Applied Analysis and Stochastics (WIAS), Berlin, from Friday Nov. 14 till Saturday Nov. 15, 2008. Already 12 years ago, WIAS had hosted a traditional Fall Meeting with special focus on classification and multivariate graphics (Mucha and Bock, 1996). This time, the special topics were stability of clustering and classification, mixture decomposition, visualization, and statistical software

Towards coherence on sustainability in education: a systematic review of Whole Institution Approaches

Orienting societies towards sustainability requires comprehensive learning of how to think, act and live within a safe and just space for humanity. Approaching sustainability as a core paradigm of quality education in the twenty-first century, Education for Sustainable Development necessitates an integrated view on learning. For educational organizations, Whole Institution Approaches (WIAs) to sustainability emphasize that all learning is embedded within its socio-physical contexts. Although the core objective—to “walk the talk” on sustainability—is theoretically well established, questions remain regarding its specific conceptualizations. Based on a systematic qualitative analysis of 104 international documents from scientific and grey literature, this article offers a conceptual synthesis of the core elements of WIAs to sustainability in education. Based on the literature analysis, WIAs are described as continuous and participative organizational learning processes aimed at institutional coherence on sustainability, consistently linking the formal and informal (hidden) curricula. While specific pathways are necessary for diverse organizations, the article synthesizes a joint framework. Key characteristics of WIAs are clustered within five core principles (coherence, continuous learning, participation, responsibility, long-term commitment), seven highly integrated areas of action (governance, curriculum, campus, community, research, communication, capacity building), the underlying organizational culture, and critical conditions for successful implementation. As becomes clear from the synthesis, following a WIA means to collaboratively switch the default mode of all rules-in-use to sustainability. The concept of WIAs may thus both be approached as an instrument for consistent organizational development in light of (un-)sustainability and as a keystone of integrated high-quality sustainability learning

Upper tails of self-intersection local times of random walks: survey of proof techniques

The asymptotics of the probability that the self-intersection local time of a random walk on $\Z^d$ exceeds its expectation by a large amount is a fascinating subject because of its relation to some models from Statistical Mechanics, to large-deviation theory and variational analysis and because of the variety of the effects that can be observed. However, the proof of the upper bound is notoriously difficult and requires various sophisticated techniques. We survey some heuristics and some recently elaborated techniques and results. This is an extended summary of a talk held on the CIRM-conference on {\it Excess self-intersection local times, and related topics} in Luminy, 6-10 Dec., 2010.Comment: 11 page

Philadelphia's Workforce Development Challenge: Serving Employers, Helping Jobseekers and Fixing the System

Over the last four years, half a billion dollars in public funds were spent in Philadelphia in the name of workforce development -- helping residents get jobs or skills and employers find workers to sustain or expand their businesses.These services, which include training for workers and recruiting for employers, were funded largely by federal and state dollars at an annual cost that ranged from $118 million to$134 million. All of these services were free of charge to workers; most were free to employers. Had these efforts been part of city government last year, and they were not, they would have constituted its fifth biggest department, surpassed only by police, fire, prisons, and human services. Roughly 1 in 10 workingage Philadelphians have sought help at a workforce development center on an annual basis. Behind this system have been two nonprofit organizations, the Philadelphia Workforce Development Corporation, which allocates most of the money, and the Philadelphia Workforce Investment Board Inc., which sets general strategy. Both are led by city appointees and are accountable to state funding agencies. For years, the performance of the two organizations received little attention from local elected officials, and their complicated division of roles sometimes led to confusion and impasses. In recent years, unpublicized state audits have found isolated problems with their financial controls.That structure is now being changed, and a new strategy is being implemented. The development corporation and most functions of the investment board are to be combined under a single agency, Philadelphia Works Inc., which will formally take over by June 2012. This report examines the workforce development system's performance, operations and challenges over the past several years -- hard economic times in which increasing numbers of Philadelphians were looking for work. It is based on extensive interviews, a review of internal audits and reports, and a statistical comparison of the system's performance with that of similar, federally mandated programs in other region

ParMooN - a modernized program package based on mapped finite elements

{\sc ParMooN} is a program package for the numerical solution of elliptic and parabolic partial differential equations. It inherits the distinct features of its predecessor {\sc MooNMD} \cite{JM04}: strict decoupling of geometry and finite element spaces, implementation of mapped finite elements as their definition can be found in textbooks, and a geometric multigrid preconditioner with the option to use different finite element spaces on different levels of the multigrid hierarchy. After having presented some thoughts about in-house research codes, this paper focuses on aspects of the parallelization for a distributed memory environment, which is the main novelty of {\sc ParMooN}. Numerical studies, performed on compute servers, assess the efficiency of the parallelized geometric multigrid preconditioner in comparison with some parallel solvers that are available in the library {\sc PETSc}. The results of these studies give a first indication whether the cumbersome implementation of the parallelized geometric multigrid method was worthwhile or not.Comment: partly supported by European Union (EU), Horizon 2020, Marie Sk{\l}odowska-Curie Innovative Training Networks (ITN-EID), MIMESIS, grant number 67571

A Kohn-Sham system at zero temperature

An one-dimensional Kohn-Sham system for spin particles is considered which effectively describes semiconductor {nano}structures and which is investigated at zero temperature. We prove the existence of solutions and derive a priori estimates. For this purpose we find estimates for eigenvalues of the Schr\"odinger operator with effective Kohn-Sham potential and obtain $W^{1,2}$-bounds of the associated particle density operator. Afterwards, compactness and continuity results allow to apply Schauder's fixed point theorem. In case of vanishing exchange-correlation potential uniqueness is shown by monotonicity arguments. Finally, we investigate the behavior of the system if the temperature approaches zero.Comment: 27 page

WIAS-TeSCA - Two-dimensional semi-conductor analysis package

WIAS-TeSCA (Two- and three-dimensional semiconductor analysis package) is a simulation tool for the numerical simulation of charge transfer processes in semiconductor structures, especially in semiconductor lasers. It is based on the drift-diffusion model and considers a multitude of additional physical effects, like optical radiation, temperature influences and the kinetics of deep impurities. Its efficiency is based on the analytic study of the strongly nonlinear system of partial differential equations – the van Roosbroeck system – which describes the electron and hole currents. Very efficient numerical procedures for both the stationary and transient simulation have been implemented. WIAS-TeSCA has been successfully used in the research and industrial development of new electronic and optoelectronic semiconductor devices such as transistors, diodes, sensors, detectors and lasers and has already proved its worth many times in the planning and optimization of these devices. It covers a broad spectrum of applications, from heterobipolar transistor (mobile telephone systems, computer networks) through high-voltage transistors (power electronics) and semiconductor laser diodes (fiber optic communication systems, medical technology) to radiation detectors (space research, high energy physics). WIAS-TeSCA is an efficient simulation tool for analyzing and designing modern semiconductor devices with a broad range of performance that has proved successful in solving many practical problems. Particularly, it offers the possibility to calculate self-consistently the interplay of electronic, optical and thermic effects

Analysis and simulations of multifrequency induction hardening

We study a model for induction hardening of steel. The related differential system consists of a time domain vector potential formulation of the Maxwell's equations coupled with an internal energy balance and an ODE for the volume fraction of {\sl austenite}, the high temperature phase in steel. We first solve the initial boundary value problem associated by means of a Schauder fixed point argument coupled with suitable a-priori estimates and regularity results. Moreover, we prove a stability estimate entailing, in particular, uniqueness of solutions for our Cauchy problem. We conclude with some finite element simulations for the coupled system

Realism And Empirical Evidence

We define realism using a slightly modified version of the EPR criterion of reality. This version is strong enough to show that relativity is incomplete. We show that this definition of realism is nonetheless compatible with the general principles of causality and canonical quantum theory as well as with experimental evidence in the (special and general) relativistic domain. We show that the realistic theories we present here, compared with the standard relativistic theories, have higher empirical content in the strong sense defined by Popper's methodology.Comment: 11 pages Latex, no figure