Persistence of Kardar-Parisi-Zhang Interfaces

The probabilities $P_\pm(t_0,t)$ that a growing Kardar-Parisi-Zhang interface remains above or below the mean height in the time interval $(t_0, t)$ are shown numerically to decay as $P_\pm \sim (t_0/t)^{\theta_\pm}$ with $\theta_+ = 1.18 \pm 0.08$ and $\theta_- = 1.64 \pm 0.08$. Bounds on $\theta_\pm$ are derived from the height autocorrelation function under the assumption of Gaussian statistics. The autocorrelation exponent $\bar \lambda$ for a $d$--dimensional interface with roughness and dynamic exponents $\beta$ and $z$ is conjectured to be $\bar \lambda = \beta + d/z$. For a recently proposed discretization of the KPZ equation we find oscillatory persistence probabilities, indicating hidden temporal correlations.Comment: 4 pages, 3 figures, uses revtex and psfi

Anti-Coarsening and Complex Dynamics of Step Bunches on Vicinal Surfaces during Sublimation

A sublimating vicinal crystal surface can undergo a step bunching instability when the attachment-detachment kinetics is asymmetric, in the sense of a normal Ehrlich-Schwoebel effect. Here we investigate this instability in a model that takes into account the subtle interplay between sublimation and step-step interactions, which breaks the volume-conserving character of the dynamics assumed in previous work. On the basis of a systematically derived continuum equation for the surface profile, we argue that the non-conservative terms pose a limitation on the size of emerging step bunches. This conclusion is supported by extensive simulations of the discrete step dynamics, which show breakup of large bunches into smaller ones as well as arrested coarsening and periodic oscillations between states with different numbers of bunches.Comment: 26 pages, 11 figure

China Incorporated

The development of entrepreneurship and a private business sector in China pose various challenges to analysis. On the one hand, neo-classically based New Institutional Economics aims to find evidence that long-term investment and long-term commitment in and around firms can not be expected without deeply entrenched and state guaranteed private property rights. On the other hand, empirical studies within the China field concentrate on the political processes, in particular the interaction between the central state and local governments, at the danger of neglecting market forces, economic interests, and economic problems at stake. The empirical study on which the following is based took a different path by using a set of framing assumptions.entrepreneurship;China;privatization;institutional economics;local governments

China’s Institutional Architecture: A New Institutional Economics and Organization Theory Perspective on the Links between Local Governance and Local Enterprises

We start our exploration of China’s institutional change by asking what the China experience can tell us about institutional economics and organization theory. We point to under-researched areas such as the formation of firms and the interplay between firms and local politics. Our findings support the dynamic capability approach which concentrates on activities rather than on pre-defined groups and models institution building as a co-operative game between the local business community and local government agencies. We find that the analysis of firms has to set in before they are formed by entrepreneurs and networks and we identify political management as a core competence of these two groups. While this contradicts the conventional view of clientelism or principle agent relations as institutional building blocks, we don’t propose competing models. Instead, we suggest focusing on a dynamic process in which the role of players can change. Faced with the spontaneous emergence of institutions, our concept of institutional architecture captures the fact that the two models can co-exist side by side and that, once the dichotomy between formal and informal institutions is given up, there can be a transition from local patron-client relations to local business-state coordination.entrepreneurship;dynamic capabilities;networks;institutional change;diversity and convergence of institutions

Entrepreneurship in Transition: Searching for governance in China’s new private sector

Entrepreneurial activities in transition economies go beyond (technical) entrepreneurship. In an environment of institutional and procedural uncertainty entrepreneurs need to select business partners, choose a mode of governance that stabilizes long term business relations, and settle for such property rights regime that best matches the entrepreneurial endeavour. Bases on fieldwork in China the paper shows how entrepreneurs combine their predisposition for social relations with economic reasoning when they embed firms in one location, in mixed forms of relational and contractual governance, and specific ownership structures. The empirical research points to alternative economic concepts which allow further analysing the interaction between individual entrepreneurship and the emergence of market conforming institutions.entrepreneurship;embeddedness;governance and institutions

Framing China: Transformation and Institutional Change

The paper offers a frame for investigating the extent to which decentralisation, and subsequent locally chosen institutions shape private organisational and institutional innovation. To include the numerous locally based “economic regimes†matters as the resulting business system reflects political institution setting and private organisational innovation. Such a frame is a necessary first step for empirical studies attempting to explain the heterogeneity of China’s business systems, the emergence of hybrid organisations, and last but none the least, the different growth rates that can be observed across China.Transition Economy;Institutional Change in China;Private Business Sector

The Emergence of a Private Business Sector in China

This paper is part of a broader research project that aims to analyse the emerging private business sector in China by focusing on three topics.entrepreneurship;networks;social capital;evolutionary economics

Damping of Oscillations in Layer-by-Layer Growth

We present a theory for the damping of layer-by-layer growth oscillations in molecular beam epitaxy. The surface becomes rough on distances larger than a layer coherence length which is substantially larger than the diffusion length. The damping time can be calculated by a comparison of the competing roughening and smoothening mechanisms. The dependence on the growth conditions, temperature and deposition rate, is characterized by a power law. The theoretical results are confirmed by computer simulations.Comment: 19 pages, RevTex, 5 Postscript figures, needs psfig.st

Simulation of a high-speed demultiplexer based on two-photon absorption in semiconductor devices

In this paper, we present a theoretical model of an all-optical demultiplexer based on two-photon absorption in a specially designed semiconductor micro-cavity for use in an optical time division multiplexed system. We show that it is possible to achieve error-free demultiplexing of a 250 Gbit/s OTDM signal (25 × 10 Gbit/s channels) using a control-to-signal peak pulse power ratios of around 30:1 with a device bandwidth of approximately 30 GHz

Magnetic coupling in highly-ordered NiO/Fe3O4(110): Ultrasharp magnetic interfaces vs. long-range magnetoelastic interactions

We present a laterally resolved X-ray magnetic dichroism study of the magnetic proximity effect in a highly ordered oxide system, i.e. NiO films on Fe3O4(110). We found that the magnetic interface shows an ultrasharp electronic, magnetic and structural transition from the ferrimagnet to the antiferromagnet. The monolayer which forms the interface reconstructs to NiFe2O4 and exhibits an enhanced Fe and Ni orbital moment, possibly caused by bonding anisotropy or electronic interaction between Fe and Ni cations. The absence of spin-flop coupling for this crystallographic orientation can be explained by a structurally uncompensated interface and additional magnetoelastic effects