The sand lizard moves downtown – habitat analogues for an endangered species in a metropolitan area

Urban Ecosystems - Urbanisation can be dangerous to biological diversity, but on the other hand cities can enhance local and regional biodiversity by providing habitat analogues for many –...     

Early Childhood Education Centre Director Perceptions of Challenging Behaviour: Promising Practices and Implications for Professional Development

Given their key role in overall programme quality, it is critical to examine how early childhood programme centre directors in the United States perceive challenging behaviour. Participants completed a survey asking which behaviours they perceive to be most problematic, the number of children dismissed or expelled from the programme during the last year, and the most commonly used strategies for addressing challenging behaviours. Results point to several promising practices and highlight the variability in access to evidence‐based practices based on programme type. Areas that warrant more targeted professional development are discussed, and findings are situated within the larger early childhood context.     

RISK AVERSION AND OVERBIDDING IN FIRST PRICE SEALED BID AUCTIONS: NEW EXPERIMENTAL EVIDENCE

Bidding above the risk‐neutral Nash equilibrium in first price sealed bid auctions has traditionally been ascribed to risk aversion. Later studies, however, offer other explanations and even argue that risk aversion plays no or a minor role. In a novel experimental design, we directly test the relationship between risk aversion and overbidding by systematically varying the distribution of risk attitudes in auction markets. We find a significant relationship between our measure of risk aversion and overbidding. (JEL D44, C91)     

Multiple hypothesis tests based On conditional differences in means

Many hypothesis tests are univariate tests and cannot cope with multiple hypothesis without an auxiliary procedure as e. g. the Bonferroni-Holm-procedure. At the same time, there is an urgent need for testing multiple hypothesis due to the very simple existing methods as the Bonferroni-correction or the Bonferroni-Holm-procedure, which suffers from a very small local significance level to detect statistical inferences or the drawback that logical and statistical dependencies among the test statistics are not used, whereby its detection is NP-hard. In honour of this occasion, we present a multiple hypothesis test for i.i.d. random variables based on conditional differences in means, which is capable to cope with multiple hypothesis and does not suffer on such drawbacks as the Bonferroni-correction or the Bonferroni-Holm-procedure. Thereby, the computation time can be neglected.     

The effect of stress on customer perception of the frontline employee: an experimental study

Review of Managerial Science - This article examines positive effects of customer stress drawn upon the theory of excitation transfer. Contrary to previous marketing and management literature, the...     

Integrative Entrepreneurship-Forschung — Identifikation von Schnittstellen zwischen soziologischer und ökonomischer Perspektive

In this paper three prominent discourses of Entrepreneurship Research — 1) the Entrepreneur as an actor in society, 2) the embeddedness of the research object of Entrepreneurship Research and 3) the determinants of entrepreneurship processes — are analyzed for possible interfaces between a sociological and economical perspective. This analyses results in a systemized portfolio of research topics, which seem to be especially attractive for such an integrative research approach. The results of a survey of 105 entrepreneurship researchers in the German speaking world underpin the relevance of the identified interfaces and allow for their priorization. That way we contribute to an integration of this field as the presented set of identified interfaces, in a first step, provides a feasible agenda for interdisciplinary (empirical) follow-up research whose results — in a second step — can build elements of an integrative concept of Entrepreneurship Research.     

Coopetition in New Product Development Alliances: Advantages and Tensions for Incremental and Radical Innovation

Coopetition (collaboration between competitors) can facilitate product innovation, but there is still debate about how it is suited to radical or incremental innovation. This paper argues that the early and later phases of coopetitive new product development (NPD) pose different benefits and risks for the innovation types. Building on the tensions approach to value creation and appropriation, we develop a series of hypotheses on the role of coopetition in NPD alliances and focal firm's innovation output. The hypotheses are tested on a quantitative data set of 1049 NPD alliances in the German medical and machinery sectors. The results show that, while coopetition is advantageous for incremental innovation in both pre‐launch and launch phases, radical innovation benefits from coopetition in the launch phase only.     

The relation between coopetition and innovation/entrepreneurship

This special issue is an outcome of the 2017 Global Innovation and Knowledge Academy (GIKA) Conference, which took place at ISEG School of Economics and Management, Lisbon, Portugal, between June 28th and 30th, 2017. As the seventh of its kind, the 2017 GIKA Conference continued to attract the attention of scholars from around the world, receiving more than 600 submissions, only 300 of which were accepted for presentation at the conference. The topic of this special issue—the relation between coopetition and innovation/entrepreneurship—had an own track at the GIKA Conference, which served as a first round review for some of the submissions to the journal. The special issue was also open for external submissions.     

On the characterization of weighted simple games

This paper has a twofold scope. The first one is to clarify and put in evidence the isomorphic character of two theories developed in quite different fields: on one side, threshold logic, on the other side, simple games. One of the main purposes in both theories is to determine when a simple game is representable as a weighted game, which allows a very compact and easily comprehensible representation. Deep results were found in threshold logic in the sixties and seventies for this problem. However, game theory has taken the lead and some new results have been obtained for the problem in the past two decades. The second and main goal of this paper is to provide some new results on this problem and propose several open questions and conjectures for future research. The results we obtain depend on two significant parameters of the game: the number of types of equivalent players and the number of types of shift-minimal winning coalitions.     

On global integer extrema of real-valued box-constrained multivariate quadratic functions

Determining global integer extrema of an real-valued box-constrained multivariate quadratic functions is a very difficult task. In this paper, we present an analytic method, which is based on a combinatorial optimization approach in order to calculate global integer extrema of a real-valued box-constrained multivariate quadratic function, whereby this problem will be proven to be as NP-hard via solving it by a Travelling Salesman instance. Instead, we solve it using eigenvalue theory, which allows us to calculate the eigenvalues of an arbitrary symmetric matrix using Newton’s method, which converges quadratically and in addition yields a Jordan normal form with \(1 \times 1\)-blocks, from which a special representation of the multivariate quadratic function based on affine linear functions can be derived. Finally, global integer minimizers can be calculated dynamically and efficiently most often in a small amount of time using the Fourier–Motzkin- and a Branch and Bound like Dijkstra-algorithm. As an application, we consider a box-constrained bivariate and multivariate quadratic function with ten arguments.