The Single-Particle density of States, Bound States, Phase-Shift Flip, and a Resonance in the Presence of an Aharonov-Bohm Potential

Both the nonrelativistic scattering and the spectrum in the presence of the Aharonov-Bohm potential are analyzed. The single-particle density of states (DOS) for different self-adjoint extensions is calculated. The DOS provides a link between different physical quantities and is a natural starting point for their calculation. The consequences of an asymmetry of the S matrix for the generic self-adjoint extension are examined. I. Introduction II. Impenetrable flux tube and the density of states III. Penetrable flux tube and self-adjoint extensions IV. The S matrix and scattering cross sections V. The Krein-Friedel formula and the resonance VI. Regularization VII. The R --> 0 limit and the interpretation of self-adjoint extensions VIII. Energy calculations IX. The Hall effect in the dilute vortex limit X. Persistent current of free electrons in the plane pierced by a flux tube XI. The 2nd virial coefficient of nonrelativistic interacting anyons XII. Discussion of the results and open questionsComment: 68 pages, plain latex, 7 figures, 3 references and one figure added plus a few minor text correction

Time Asymmetric Quantum Physics

Mathematical and phenomenological arguments in favor of asymmetric time evolution of micro-physical states are presented.Comment: Tex file with 2 figure

Explaining social exchanges in information-based online communities

Purpose – The purpose of this paper is to provide platforms for members to exchange information by information-based online communities (IBOCs, like LinkedIn or Facebook). Because member participation is vital for IBOCs, this research aims to identify and validate factors that drive member participation. Design/methodology/approach – With reference to social exchange theory the authors developed a model of antecedents of participation in IBOCs that was tested with survey data using PLS. Because some of the results contradicted the theory, the authors examined those results in a mainly qualitative study with online community providers. These experts offered explanations that inform the discussion and managerial implications. Findings – Role clarity, provider’s responsiveness, and enjoyment all influence member participation. Contrary to theory, the cooperation of other members affects member participation negatively while a member’s ability shows no effect. Practical implications – This research has several implications for IBOC providers. Because ability does not affect participation directly, providers do not need to worry about lacking ability and can effectively target all potential members. The importance of provider responsiveness signals that IBOC providers should proactively monitor members’ compliance with social norms to lower the social risk for members. The impact of community-specific knowledge and enjoyment on participation puts emphasis on careful community design and the thoughtful implementation of new features that might enhance enjoyment, but reduce role clarity. Originality/value – Whereas most of the participation literature focusses on a dyadic relationship, the research investigates the triadic relationship in which the provider is only an enabler of exchange. Furthermore, the authors bring together two streams of the literature: the participation literature, which tends to focus on offline participation; and the online community literature, which has not yet investigated participation. This is also the first paper to investigate nonlinear effects on participation. Keywords World wide web, Social exchange theory, Information exchange, Customer participation, Customer integration, Online communit

Relative Measures in Service Research

Purpose - The purpose of this paper is to introduce an alternative novel approach to measurement of customer perceptions of the service experience that links closely with customer loyalty outcomes. Design/methodology/approach - This conceptual paper draws upon prior theory and empirical research to investigate the relevance of using relative metrics compared to absolute metrics in service research. Findings - The findings upon which this paper draws upon show that measuring customer satisfaction, likelihood to recommend, brand preference using absolute metrics explain a very small per cent of the variance in key customer outcome measures such as share of wallet. Instead, a relative approach to these and other measures in service research is proposed. Practical implications - Although business practice has embraced relative measurement much more extensively than has scientific research, the vast majority of customer experience measurement programs today continue to employ absolute measures resulting in suboptimal allocation of firm resources. This paper is a call to rethink these current measurement practices. Originality/value - It is one of the first papers to argue for changing the widely employed use of absolute metrics in theory and practice in favor of relative metrics. Application to other service research theories is discussed