On-line bin packing with restricted repacking

Semi-on-line algorithms for the bin-packing problem allow, in contrast to pure on-line algorithms, the use of certain types of additional operations for each step. Examples include repacking, reordering or lookahead before packing the items. Here we define and analyze a semi-on-line algorithm where for each step at most k items can be repacked, for some positive integer k. We prove that the upper bound for the asymptotic competitive ratio of the algorithm is a decreasing function of k, which tends to 3/2 as k goes to infinity. We also establish lower bounds for this ratio and show that the gap between upper and lower bounds is relatively small.     

Fast computation of spatially adaptive kernel estimates

Kernel smoothing of spatial point data can often be improved using an adaptive, spatially varying bandwidth instead of a fixed bandwidth. However, computation with a varying bandwidth is much more demanding, especially when edge correction and bandwidth selection are involved. This paper proposes several new computational methods for adaptive kernel estimation from spatial point pattern data. A key idea is that a variable-bandwidth kernel estimator for d-dimensional spatial data can be represented as a slice of a fixed-bandwidth kernel estimator in \((d+1)\)-dimensional scale space, enabling fast computation using Fourier transforms. Edge correction factors have a similar representation. Different values of global bandwidth correspond to different slices of the scale space, so that bandwidth selection is greatly accelerated. Potential applications include estimation of multivariate probability density and spatial or spatiotemporal point process intensity, relative risk, and regression functions. The new methods perform well in simulations and in two real applications concerning the spatial epidemiology of primary biliary cirrhosis and the alarm calls of capuchin monkeys.     

EARLY ROUND UPSETS AND CHAMPIONSHIP BLOWOUTS

In equilibrium play of a two-round tournament, we find that underdogs exert more effort in the opening round whereas favorites save more effort for the final. Ability differences are therefore compressed in the opening round so upsets are more likely and amplified in the final so blowouts are more likely. Measures that reduce the need to strategically allocate effort make for a more exciting final but a less exciting opening round. Consistent with the model, introduction of a rest day between matches in the NCAA men's basketball tournament increased the favorite's victory margin in the semifinals by about five points.(JEL L83 , D72 )     

Wie ehrlich berichten männliche Jugendliche über ihr delinquentes Verhalten?

Survey-based studies on the prevalence and causes of deviant behaviour very much depend on the honesty of respondents. However, the validity of self-reports is rarely investigated. We report on a external validation of self-reported delinquency of male juveniles based on two survey samples — face-to-face interviews in households (N=309), and paper and pencil interviews in school (N=337) — which have been done in 1999 and 2000 in Freiburg and are used for record checks of self-reported police contacts both on the individual and aggregate level. Individual-level record checks reveal that a majority of respondents has honestly reported contacts with the police, while there are a considerable number of both ‘false negative’ and ‘false positive’ answers which come predominately from respondents with low educational and social status and of migration background. As these groups show high non-response rates as well, the correlation between delinquency and socio-economic status is likely to be underestimated. The school survey, on the other hand, yields higher and more realistic prevalence rates. However, comparisons between the two survey modes hint at differential effects of social desirability which question the validity of self-reports by respondents with high educational status. Survey results on self-reported delinquency should generally be interpreted with great caution, and more research on the mode effects of class room interviews are deemed necessary.     

Optimal designs for non-competitive enzyme inhibition kinetic models

In this paper, we present a new method for determining optimal designs for enzyme inhibition kinetic models, which are used to model the influence of the concentration of a substrate and an inhibition on the velocity of a reaction. The approach uses a nonlinear transformation of the vector of predictors such that the model in the new coordinates is given by an incomplete response surface model. Although there exist no explicit solutions of the optimal design problem for incomplete response surface models so far, the corresponding design problem in the new coordinates is substantially more transparent, such that explicit or numerical solutions can be determined more easily. The designs for the original problem can finally be found by an inverse transformation of the optimal designs determined for the response surface model. We illustrate the method determining explicit solutions for the D-optimal design and for the optimal design problem for estimating the individual coefficients in a non-competitive enzyme inhibition kinetic model.     

Social network analysis and the evaluation of leadership networks

Leadership development practitioners are increasingly interested in social networks as a way to strengthen relationships among leaders in fields, communities, and organizations. This paper offers a framework for conceptualizing different types of leadership networks and uses case examples to identify outcomes typically associated with each type of network. Evaluating leadership networks is a challenge for the field of leadership development. Social network analysis (SNA) is an evaluation approach that uses mathematics and visualization to represent the structure of relationships between people, organizations, goals, interests, and other entities within a larger system. In this article we describe core social network concepts and the application of them to illuminate the value of SNA as an evaluation tool.     

“It’s not tolerance I’m asking for, it’s respect!” A conceptual framework to differentiate between tolerance, acceptance and (two types of) respect

Due to a rising interest in empirical ‘respect’ research but at the same time a somewhat fuzzy use of the term and its semantically close neighbors, we introduce a conceptual framework. The framework draws on existing philosophical traditions and empirical psychological works alike. It is pointed out that respect, acceptance, and tolerance are all attitudes of a subject towards an object which are not aligned on one dimension, but are concerned with quite different issues. Moreover, we propose that research needs to differentiate between two very different kinds of respect. Whereas appraisal respect, acceptance, and tolerance are attitudinal reflections of a subject’s decisions on certain issues (i.e., on influence, membership, and presence), recognition respect is proposed to be an overarching processing mode, i.e., a general attitude on how to confront others.     

A Branch and Cut solver for the maximum stable set problem

This paper deals with the cutting-plane approach to the maximum stable set problem. We provide theoretical results regarding the facet-defining property of inequalities obtained by a known project-and-lift-style separation method called edge-projection, and its variants. An implementation of a Branch and Cut algorithm is described, which uses edge-projection and two other separation tools which have been discussed for other problems: local cuts (pioneered by Applegate, Bixby, Chvátal and Cook) and mod-k cuts. We compare the performance of this approach to another one by Rossi and Smiriglio (Oper. Res. Lett. 28:63–74, 2001) and discuss the value of the tools we have tested.