University of Paderborn

About: University of Paderborn is a education organization based out in Paderborn, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Computer science & Context (language use). The organization has 6684 authors who have published 16929 publications receiving 323154 citations.

Theoretical study of vacancy diffusion and vacancy-assisted clustering of antisites in SiC

Abstract: Using the self-consistent-charge density-functional-based tight-binding (SCC-DFTB) method, we have investigated the migration of vacancies at high temperatures, taking into account the entropy contribution to the Gibbs free energy. We have found that the energy barrier for sublattice migration of ${V}_{\mathrm{Si}}$ is lower than that for ${V}_{\mathrm{C}},$ so that ${V}_{\mathrm{Si}}$ should anneal out at lower temperatures, which agrees with the experimental observations for as-grown SiC. In irradiated material, vacancies and interstitials are expected to appear in high concentrations. In the early stages of annealing, their recombination can also result in antisites. We show that at annealing temperatures at which vacancies are mobile, their motion can mediate the migration of antisites. The vacancy-assisted diffusion of carbon antisites is much faster than that of silicon antisites and may lead to the formation of carbon antisite clusters. We propose a mechanism for the formation of antisite clusters during the migration of silicon vacancies. The role of these complexes in the formation of very stable defects, observed in irradiated SiC, is discussed, additionally.

Platform Launch Strategies

Abstract: Today, digital platforms mediating between independent groups of users account for a total market value of about US-$4.3 trillion and an employment base of several million direct and indirect employees (Evans and Gawer 2016). A multi-sided platform (MSP) – in the literature also referred to as two-sided platform, two-sided market, or multi-sided market – constitutes a market that enables interaction between at least two sets of users through an intermediary, where the decisions of each group of users on either side of the market affects the outcomes of the users on the other side(s) (Rochet and Tirole 2004; Rysman 2009; Hagiu and Wright 2015). MSPs have impressively demonstrated their disruptive potential in well-established global industries. Airbnb, for instance, leads the CNBC disruptor 50 list (CNBC 2017) and, with a market valuation of US$31 billion, comes second after the Marriott group in the lodging industry (Bensinger 2017). Its two-sided platform mediates between traveling people who seek accommodation and hosts willing to share their accommodation. The exponential growth of its platform started around 2011, when the critical inflection point (in respect of the number of users) was reached and network effects started to kick in (Hagiu and Rothman 2016). As the first in its industry, Airbnb has been able to solve one of the critical early-stage challenges of MSPs, namely the mutual baiting problem, which often is referred to as the ‘chicken-and-egg dilemma’ of multi-sided digital platforms. MSPs have been a popular research topic for scholars in the fields of economics, strategic management, and, more recently, as a consequence of the emergence of large-scale web-based platforms, to information systems scholars. Two major streams of research on MSPs can be distinguished. The first stream examines pricing and commission choices (Armstrong 2006; Chao and Derdenger 2013; Dou et al. 2016; Eisenmann et al. 2006; Parker and Van Alstyne 2005; Rochet and Tirole 2003, 2006; Rysman 2009), while the second stream investigates choices with regard to platform design and investments, such as the quality of technology and rules of interaction (Bakos and Katsamakas 2008), the effects of advertisement (Tucker and Zhang 2010) and ownership model (Yoo et al. 2002), business model design (Hagiu and Wright 2015), value-added services (Anderson et al. 2014), competition among platforms Accepted after one revision by Prof. Dr. Weinhardt.

Entrepreneurship and regional economic growth: towards a general theory of start-ups

Abstract: Start-ups of new firms are important for economic growth. However, start-up rates differ significantly between countries and within regions of the same country. A large empirical literature studies the reasons for this and endeavours to identify the regional determinants of start-ups. By contrast, there is a much smaller theoretical literature attempting the formal modelling of the start-up process within a region. In this article, we seek to contribute to this small literature by introducing a general theoretical model of the entrepreneurial start-up process. The model links start-ups to economic growth and can be applied to understand growth in a regional context. We derive a number of propositions which fit the stylised facts from the empirical literature: (i) growth in the regional economy is driven by an expansion in the number of start-up firms supplying intermediate goods and services; (ii) improvements in human capital will improve the rate of start-ups; (iii) improvements in the relative rates of...

The Role of Prior Entrepreneurial Exposure in the Entrepreneurial Process: A Review and Future Research Implications

Abstract: Despite considerable research, the current state regarding how and in which context prior entrepreneurial exposure impacts the entrepreneurial process is unclear. The present paper's goal is to systemize and discuss extant quantitative-empirical research on the role of prior entrepreneurial exposure in the entrepreneurial process to clarify the current state, identify research gaps, and offer future research directions. Results from the systematic literature review of 69 quantitative-empirical journal articles suggest that prior findings are ambiguous and theoretical shortcomings exist. We contribute to the literature by clarifying the current state and by offering directions for entrepreneurship research and practitioners promoting entrepreneurial activity.

Observation of Genuine Three-Photon Interference.

Abstract: Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with (92.7±4.6)% visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics, and quantum information applications in higher dimensions.