Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

On the Ex Ante Valuation of IT Service Investments

The paradigm of service orientation and its incarnation in the form of service-oriented architecture (SOA) and information technology (IT) services play a crucial role in enabling companies to achieve considerable competitive advantages. However, to be able to leverage the opportunities of SOA and IT services, companies need to gain a thorough understanding of the business value of IT service investments. Nevertheless, research on IT services has focused mainly on technical questions so far; the economic perspective largely has been neglected. Therefore, the authors aim to contribute to the ex ante valuation of IT service investments from a decision theoretical point of view. Using decision theory as a theoretical base, the main aim is to identify and discuss specific challenges regarding the financial ex ante valuation of IT service investments, which arise from the inherent flexibility of IT services and the various interdependencies within a company’s IT service portfolio. The authors thereby emphasize that the application of common methods from financial theory for valuating IT service investments has to be treated with caution, as these methods are often tied to rather restrictive assumptions based on the specifics of capital markets. By analyzing different clusters of IT service investment decision problems using decision theory, the authors identify and discuss pitfalls that might occur when applying financial valuation methods to capture the flexibility and interdependencies of IT service investments. The decision theoretical considerations are intended to help build a solid basis for future multi-criteria valuation approaches, of which an essential component is a theoretically well-founded financial valuation

Economic growth versus preservation of the environment A model-theoretic approach

SIGLEDEGerman

Die optimale Investitionsquote der energieabhaengigen Volkswirtschaft

SIGLEBibliothek Weltwirtschaft Kiel C119,679 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Optimal new-capital-investment policies for economies with finite capital longevity and technical progress

SIGLEBibliothek Weltwirtschaft Kiel C 111,620 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

The route to resource-efficient novel materials

Combining the efforts of physicists, materials scientists, economists and resource-strategy researchers opens up an interdisciplinary route enabling the substitution of rare elements by more abundant ones, serving as a guideline for the development of novel materials