Modelling columnarity of pyramidal cells in the human cerebral cortex

For modelling the location of pyramidal cells in the human cerebral cortex, we suggest a hierarchical point process in that exhibits anisotropy in the form of cylinders extending along the z-axis. The model consists first of a generalised shot noise Cox process for the xy-coordinates, providing cylindrical clusters, and next of a Markov random field model for the z-coordinates conditioned on the xy-coordinates, providing either repulsion, aggregation or both within specified areas of interaction. Several cases of these hierarchical point processes are fitted to two pyramidal cell data sets, and of these a final model allowing for both repulsion and attraction between the points seem adequate. We discuss how the final model relates to the so-called minicolumn hypothesis in neuroscience.     

Semiparametric multiparameter regression survival modeling

We consider a log-linear model for survival data, where both the location and scale parameters depend on covariates, and the baseline hazard function is completely unspecified. This model provides the flexibility needed to capture many interesting features of survival data at a relatively low cost in model complexity. Estimation procedures are developed, and asymptotic properties of the resulting estimators are derived using empirical process theory. Finally, a resampling procedure is developed to estimate the limiting variances of the estimators. The finite sample properties of the estimators are investigated by way of a simulation study, and a practical application to lung cancer data is illustrated.     

Modification of shiftwork effects by chemical workplace exposure

Abstract

Possible chronotoxic effects were the reason to study chemical workplace exposure under the special condition of shiftwork. Eight shiftworkers occupationally exposed to acetone vapours and eight controls were investigated during fast-rotated shiftwork. The mean concentration of acetone during the shifts was close to 1000 ppm (2400 mg/m³). Data on well-being and acute symptoms, but not on performance, indicate that the exposure contributed mainly in an additive way to the negative effects of shiftwork. As a consequence, the exposed shiftworkers revealed enhanced impairments during the night-shift.     

Allocation of seminar applicants

The allocation of seminar applicants is an important issue in educational planning, and each semester a university administration has to deal with this kind of problem. The task here is to reconcile the preferences and priorities of the students, professorships and the university administration itself. This paper shows that if the planning procedure is based on a simple selection strategy, the capacity utilization can be suboptimal; this result is evidenced by a simulation study. To remedy this deficit—and to justify the respective interests—we propose a mixed-integer goal programming approach for assigning students to seminar courses. In addition, we show that this problem can be reformulated into a linear one. All investigations in this paper are illustrated by a real-world application for the University of Hagen, Germany.     

Tax attractiveness and the location of German-controlled subsidiaries

This paper analyzes whether taxation has an influence on the location decisions of multinational enterprises. We employ a novel set of 22 tax variables, such as the taxation of dividends and capital gains, withholding taxes, the existence of a group taxation regime, and thin capitalization rules. Furthermore, we use the Tax Attractiveness Index, a new aggregate measure containing the 22 tax variables. Our count data regression analysis is based on a novel hand-collected dataset consisting of the subsidiaries of German DAX30 companies in 97 countries. Controlling for non-tax effects, we find that a country’s tax environment has a significantly positive effect on the number of German-controlled subsidiaries and, therefore, on the location decisions of German multinational enterprises. Specifically, our analysis reveals that German multinational firms place affiliates in countries that offer favorable statutory tax rates, withholding taxes, double tax treaty networks, and holding incentives. Additionally, we find that the Tax Attractiveness Index has explanatory power in subsidiary location decisions and, therefore, it can be used as alternative composite measure, for example, when 22 single tax variables are not at disposal.     

The Role of Organizational Identities for Policy Integration Processes – Managing Sustainable Transport Development

Sustainable transport development is a complex, but necessary issue to manage if the use of fossil energy will decrease and transportation become more energy-efficient and environmental friendly. The contemporary public organization is organized into policy sectors and tiers of government, but the issue of sustainability is not confined to one single sector or level, it transcends all these traditional boundaries. To address this complexity policy integration has been suggested as a way for public organizations to open up the sectoral and vertical boundaries in policymaking. This paper discusses a case study of a political committee on the regional level in Sweden, which has been formed for integrated policymaking between sectors and local and regional authorities to manage sustainable transport development. The analysis of the case shows that vertical and sectoral integration are dependent processes and that the relation between different organizational identities either strengthens or undermine them. Vertical integration is not resulting in sectoral integration, rather it works prohibiting against sectoral integration.     

Pathways to social value and social change: An integrative review of the social entrepreneurship literature

Social entrepreneurship has emerged as an important means of addressing grand challenges. Although research on the topic has accelerated, scholars have yet to articulate an overarching framework that links the different pathways taken by social entrepreneurs with the positive effects of these efforts. To address this shortcoming, we conducted a systematic literature review which enabled us to conceptually differentiate between social value and social change as distinct outcomes of social entrepreneurship and identify seven pathways for achieving these outcomes. Building on our analysis, we outline a research agenda for questions pertaining to: the dynamics between social value and social change; how contextual factors and social entrepreneurs influence various pathways; design principles of business models and innovations that facilitate social value and social change; and defining, measuring, and ensuring accountability for social value and social change.     

Groupthink and Project Performance: The Influence of Personal Traits and Interpersonal Ties

This study explores whether the negative impact of “groupthink concurrence‐seeking behavior” (GTB) on business process reengineering (BPR) projects is affected by group members personal traits and interpersonal ties within the group. To this purpose we conduct and present the results of a longitudinal controlled field experiment over 18 BPR projects lasting 3 months and involving 18 teams comprising 71 first‐year MBA students. The main contribution of this study is twofold. First, we explicitly consider and measure the core construct of groupthink phenomenon: that is, GTB. Existing organizational behavior literature has, contrarily, considered only its causes, symptoms, and outcomes. Second, we show evidence that GTB does have a negative impact on group performance in BPR project settings. In this regards, results also indicate that while perceived control, conscientiousness and interpersonal evaluation mitigate the negative impact of GTB on group project performance, confidence, and previous relationships amplify this negative impact, even if they have a direct positive effect on performance. Thanks to the findings of this study, we are able to provide valuable suggestions to managers in charge of BPR projects for ensuring effective performance of project teams and controlling for potential obstacles due to GTB.     

RESOURCE ALLOCATION TO IMPROVE SERVICE QUALITY PERCEPTIONS IN MULTISTAGE SERVICE SYSTEMS

Service quality improvement has become an imperative in today's service firms. In this paper, we present a modeling framework that combines marketing and operations viewpoints for resource allocation. The framework can be used to allocate resources to the different stages of a multistage service system, where the manager's goal is to improve customers' perceptions of service quality, given some budget. Optimal allocation guidelines are provided, and the interplay of three factors on the resulting allocation scheme is captured. These factors are the current level of customers' perceptions of service quality at each stage, the cost of implementing a service quality improvement at each stage, and the importance placed by customers at each stage. Sensitivity analysis to provide additional managerial insights is also performed. We demonstrate the applicability of the modeling framework, using data from a real life health care environment. Model limitations and future research are also discussed.