Vorschau

RedaktionVorschau

Vorschau Unsere Themen im n?chsten Heft     

Optimal consumption and investment under partial information

We consider a stock market model where prices satisfy a stochastic differential equation with a stochastic drift process. The investor’s objective is to maximize the expected utility of consumption and terminal wealth under partial information; the latter meaning that investment decisions are based on the knowledge of the stock prices only. We derive explicit representations of optimal consumption and trading strategies using Malliavin calculus. The results apply to both classical models for the drift process, a mean reverting Ornstein-Uhlenbeck process and a continuous time Markov chain. The model can be transformed to a complete market model with full information. This allows to use results on optimization under convex constraints which are used in the numerical part for the implementation of more stable strategies. Supported by the Austrian Science Fund FWF, project P17947-N12. We thank two anonymous referees for their comments which led to a considerable improvement of the paper.     

Calling party pays or receiving party pays? The diffusion of mobile telephony with endogenous regulation

This paper analyzes the impact on mobile telephony diffusion patterns of the two predominant payment regimes, calling party pays (CPP) and receiving party pays (RPP), for mobile termination services. By applying instrumental variable techniques to panel data we account for a possible interdependency of penetration rates and regulatory interventions. For this purpose we use data on political and institutional factors to instrument endogenous regulatory decisions. We conclude from our empirical analysis that there is no significant impact of either RPP or CPP on penetration rates. Therefore an application of RPP in order to obviate regulation of termination fees would be feasible.     

Injury incidence,risk perception and product-related safety behavior among 18- and 45-year-olds

Abstract

Adolescents generally have twice the injury incidence of adults. This increased risk of injury may partly be a consequence of the types of activities performed, the level of exposure to products and the safety behavior. The purpose of this paper was to identify possible predictors for the increased injury risk of adolescents compared to adults. To this end, all 18- and 45-year-olds in a major city in Norway received a questionnaire asking for information on injury experience, level of use and risk perceptions concerning 14 specific products, and the adoption of safety measures; 686 18-year-olds and 81 o 45-year-olds answered the questionnaire. The adolescents reported a higher injury incidence as compared to adults for all the listed products. The difference was significant even after controlling for level of use. Adolescents also had higher levels of risk perception and decreased adoption of safety measures as compared to adults. Females reported less injuries but higher levels of risk perception than males. Females also adopted more safety measures. An important finding from this study was that adolescents, as compared to adults, also expose themselves to increased risk levels when ‘ordinary’ products are concerned, and not only in terms of well-known high-risk activities (driving fast, skiing downhill, etc.). This tends to support the idea that more general factors or dimensions of risk-related behaviors may exist which should be accounted for in the planning of injury prevention activities.     

Exponential inequalities for ruin probabilities in the Cox case

Abstract

We consider an insurance model where the underlying point process is a Cox process. Using a martingale approach we obtain extensions of the classical Lundberg inequality.     

Subsidiary roles,vertical linkages and economic development: Lessons from transition economies

Vertical supply chain linkages between foreign subsidiaries and domestic firms are important mechanisms for knowledge spillovers, contributing to the economic development of host economies. This paper argues that subsidiary roles and technological competences affect the extent of vertical linkages as such as well as their potential for technological spillovers. Using survey evidence from 424 foreign subsidiaries based in transition economies, we tested for the effect of subsidiaries’ autonomy, initiative, technological capability, internal and external technological embeddedness on the extent and intensity of forward and backward vertical linkages. The evidence supports our main argument that the potential of technology diffusion via vertical linkages depends on the nature of subsidiary roles. We discuss the implications for transition as well as other developing countries.     

Scaling of HIS in a global context: Same,same, but different

Scaling of information systems is a field of research with growing importance. This paper presents the story of scaling of an artifact (called District Health Information Software — DHIS) and associated principles and practices around a health information system that has taken place over 15 years, both within and between multiple developing countries. Through the lens of the story of the artifact over its trajectory of development and implementation in multiple contexts and time, we develop insights that challenge traditional thinking around scaling. Scaling is not about constant gains and expansion, as is often assumed, but involves a dichotomy of losses and gains, associated with each step or translation in its process of movement. We draw upon Latour's insights on circulating references to analyze this dichotomy of loss and gains, conceptualizing the process as circulating translations. We contribute to the technology transfer literature in arguing that the process of transfer is not about a “parachuting” from point A to B, or a “design from nowhere” but something which occurs in a series of small steps, where with each step new socio-technical configurations are created which not only shape subsequent steps, but also redefine the content of the artifact. In this way, we are in line with findings from the social studies of technology, but differ in that our artifact of study – software – is more “virtually immaterial” than machines which had been primarily earlier objects of study. This property of software, coupled with growth of web-based and mobile infrastructure, allows relative ease of circulation across contexts, where it gets redefined and embedded at the same time at the interconnected levels of the global and local. We conceptualize this process of global scaling as being “same, same, but different”. We discuss both the characteristics of this process of global scaling, and the channels and mechanisms through which it takes place. Four overlapping conditions that shape this process include the software itself, the infrastructure, institutional practices, and ideas — these form the basis for a general framework to understand global scaling of health information systems. Empirically, the story of DHIS is told from its birth in the mid-nineties in South Africa developed on a Microsoft platform to its transformation to a web-based platform, built using Java based open-source frameworks, and now moving through multiple countries. We focus on these dynamics primarily within three countries namely India, Sierra Leone and Kenya.     

Minimising the harm to biodiversity of producing more food globally

Should farming and conservation policies aim broadly to separate land for nature and land for production (land sparing) or integrate production and conservation on the same land (wildlife-friendly farming)? Most studies that try to address this question suffer from flaws in sampling design, inappropriate metrics, and/or failure to measure biodiversity baselines. We discuss how these failings can be addressed, and what existing information tells us about the key debates on this topic. The evidence available suggests that trade-offs between biodiversity and yield are prevalent. While there are some wildlife-friendly farming systems that support high species richness, a large proportion of wild species cannot survive in even the most benign farming systems. To conserve those species, protection of wild lands will remain essential. Sustainable intensification could help to facilitate sparing of such lands, provided that as much attention is given to protecting habitats as to raising yields. We discuss the general circumstances under which yield increases can facilitate land sparing, recognising that policies and social safeguards will need to be context-specific. In some situations, bringing degraded lands into production could help reduce pressure on wild lands, but much more information is needed on the biodiversity implications of using degraded lands. We conclude that restricting human requirements for land globally will be important in limiting the impacts on biodiversity of increasing food production. To achieve this, society will need to integrate explicit conservation objectives into local, regional and international policies affecting the food system.