Spectral asymptotics of the Laplacian on supercritical bond-percolation graphs

We investigate Laplacians on supercritical bond-percolation graphs with different boundary conditions at cluster borders. The integrated density of states of the Dirichlet Laplacian is found to exhibit a Lifshits tail at the lower spectral edge, while that of the Neumann Laplacian shows a van Hove asymptotics, which results from the percolating cluster. At the upper spectral edge, the behaviour is reversed.Comment: 16 pages, typos corrected, to appear in J. Funct. Ana

Benefits and Challenges of Business Intelligence Adoption in Small and Medium-Sized Enterprises

Leveraging information is a key success factor for companies. Over the last two decades BusinessIntelligence (BI) has evolved to become a foundational cornerstone of enterprise decision support.However, prior research shows that small and medium-sized enterprises (SMEs), in particular, lagbehind in the proliferation of BI. In this exploratory study we examine BI adoption within GermanSMEs in the state of Saxony (n = 214). We explore perceived benefits and challenges in their efforts toimplement BI. By applying cluster analysis to these results we suggest four types of BI SMEs, eachwith an individual profile concerning potential benefits as well as a certain set of challenges that areto be expected when it comes to adopting BI solutions. Results can create value for enterprises thatplan to implement a BI solution, BI consultants as well as BI suppliers

Peer Methods for the Solution of Large-Scale Differential Matrix Equations

We consider the application of implicit and linearly implicit (Rosenbrock-type) peer methods to matrix-valued ordinary differential equations. In particular the differential Riccati equation (DRE) is investigated. For the Rosenbrock-type schemes, a reformulation capable of avoiding a number of Jacobian applications is developed that, in the autonomous case, reduces the computational complexity of the algorithms. Dealing with large-scale problems, an efficient implementation based on low-rank symmetric indefinite factorizations is presented. The performance of both peer approaches up to order 4 is compared to existing implicit time integration schemes for matrix-valued differential equations.Comment: 29 pages, 2 figures (including 6 subfigures each), 3 tables, Corrected typo

Model-based classification of regional labour markets : for purposes of labour market policy

"In many countries fairly large and persistent regional disparities can be observed for a variety of economic indicators. Since these disparities can not be reduced to one single dimension, a classification system is needed to give a parsimonious overview. The article presents a system which is designed to assess labour market policy in Germany. The innovation in this article is the development of a procedure that combines the analysis of determinants of regional disparities with standard classification approaches. The procedure is designed to solve two problems of many existing classification schemes: firstly, their purely descriptive nature and secondly, their interpretation with relation to arbitrarily chosen classification variables. The proposed method is used to identify 12 types which show the regional diversity of labour markets in Germany." (Author's abstract, IAB-Doku) ((en))Arbeitsmarktforschung, Wirkungsforschung, Arbeitsmarktpolitik, Ausbildungsabsolventen, Berufseinmündung, berufliche Integration, Arbeitslose, regionaler Arbeitsmarkt, regionaler Vergleich, regionale Disparität, Indikatorenbildung, Arbeitsmarktindikatoren, Klassifikation, Klassifikationsmethode, Clusteranalyse, Region - Typologie

Wave Packet Dynamics, Ergodicity, and Localization in Quasiperiodic Chains

In this paper, we report results for the wave packet dynamics in a class of quasiperiodic chains consisting of two types of weakly coupled clusters. The dynamics are studied by means of the return probability and the mean square displacement. The wave packets show anomalous diffusion in a stepwise process of fast expansion followed by time intervals of confined wave packet width. Applying perturbation theory, where the coupling parameter v is treated as perturbation, the properties of the eigenstates of the system are investigated and related to the structure of the chains. The results show the appearance of non-localized states only in sufficiently high orders of the perturbation expansions. Further, we compare these results to the exact solutions obtained by numerical diagonalization. This shows that eigenstates spread across the entire chain for v>0, while in the limit v->0 ergodicity is broken and eigenstates only spread across clusters of the same type, in contradistinction to trivial localization for v=0. Caused by this ergodicity breaking, the wave packet dynamics change significantly in the presence of an impurity offering the possibility to control its long-term dynamics.Comment: 10 pages, 9 figure

Pure point diffraction implies zero entropy for Delone sets with uniform cluster frequencies

Delone sets of finite local complexity in Euclidean space are investigated. We show that such a set has patch counting and topological entropy 0 if it has uniform cluster frequencies and is pure point diffractive. We also note that the patch counting entropy is 0 whenever the repetitivity function satisfies a certain growth restriction.Comment: 16 pages; revised and slightly expanded versio

Heterogeneity in the Evaluation of Quality Assurance Systems: The International Food Standard (IFS) in European Agribusiness

Due to the growing demands of customers and several food crises, quality assurance schemes have become increasingly popular in agribusiness. With this trend in mind, it seems worthwhile to take a closer look at the satisfaction of participating European companies. The study focuses on the IFS, which has gained much relevance in the food industry. A questionnaire concerned with perceptions of the advantages and disadvantages of the IFS was answered by 389 companies. The results indicate that the overall evaluation of the IFS is primarily affected by the perceived usefulness of the catalogue of requirements and its evaluation. Furthermore, a cluster analysis was conducted and three clusters were identified, representing heterogeneous evaluations of the IFS.evaluation, quality assurance systems, International Food Standard, agribusiness, Agribusiness, Food Consumption/Nutrition/Food Safety, Q10, Q13, Q18,