African agricultural productivity and the transatlantic slave trade: evidence from Senegambia in the nineteenth century

Agriculture has played a central role in Africa's long‐term economic development. Previous research has argued that the low productivity of African economies has posed significant challenges to African efforts to produce an agricultural surplus or to develop commercial agriculture. Low agricultural productivity has also served as a key explanation for the transatlantic slave trade, on the basis that it was more profitable to export humans overseas than to grow and export produce. However, the field has suffered from a lack of comparable empirical evidence. This article contributes to this field by presenting quantitative data on historical land and labour productivity in Africa, from a case study of the agricultural productivity of Senegambia in the early nineteenth century. Focusing on five key crops, our results suggest that both land and labour productivity was lower in Senegambia than it was in all other parts of the world for which we have found comparable data. This article thus lends support to claims that stress ecological factors as one of the main determinants of Africa's historical development.     

Fernseherziehung in der Deutschschweiz

Parents’ influence on and monitoring of children’s television use has been investigated intensely. In recent years international research has identified different environmental and family factors which influence active mediation, restrictive mediation, and co-viewing. However, there has been no systematic simultaneous comparison of the impact of these factors in German-speaking Switzerland. Therefore the present study analyzes the impacts of parental attitudes as well as family and environmental factors on parental mediation of children’s TV use simultaneously. 252 parents of children aged 3 to 14 answered questions concerning the impact factors, their mediation behaviour as well as children’s media use. Results confirm findings from international research: Most important for parental mediation styles are parental attitudes and the family communication style as well as children’s age. Structural and other sociodemographical factors seem to be less important.     

Geothermische Stromerzeugung in Deutschland — Stiefkind oder schlafender Riese?

This contribution analyses the development of power generation from geothermal energy in Germany. It considers research funding schemes, the support through the german Renewable Energy Sources Act (EEG) and the role of decisive actors as well as technical, economic and societal framework conditions. Compared to other renewable energy sources research funding for geothermal energy had played an inferior role in the past. After the potentials for geothermal power generation had been underlined by a study in 2003, geothermal power gained more political and institutional advocates. Subsequently it was equipped with a higher tariff in the EEG 2004 and led to realization of demonstration projects. Yet, the appliance of technologies for electrical power transformation, ORC and Kalina, are at the very beginning. Presently, the geothermal energy industry consists of a small amount of medium-sized businesses. Regional and nationwide energy providers, acting as operators and investors, do not exert much pressure in view of limited returns. Despite the compatibility with existing power supply systems, constraints to the expansion of geothermal energy use — above all exploration risks and high drilling costs- are likely to lead to a step-by step enhancement rather than a rush.     

Innovation and the circular economy: A systematic literature review

The circular economy emerged as an alternative model to the linear system, which now appears to be reaching its physical limitations. To transition to a circular economy, companies must not only be aware of but also engage in more sustainable practices. For such a transition, companies must rethink and innovate their business models and the ways they propose value to their clients while simultaneously considering environmental and social facets. This systematic literature review sought to map out from the company perspective the key topics interrelated with innovation and the circular economy, describing the internal and external factors to consider in such transition processes. Key lines of research were identified, and suggestions for future research and for facilitating movement toward a circular economy are provided. This work contributes to deepening the literature by identifying the priority areas concerning the circular economy and encouraging future research that meets international standards of excellence.     

Effort maximization in asymmetric contest games with heterogeneous contestants

Contest rules are set up by administrators who frequently have discretionary power in specifying the details of these rules, i.e., they can bias the contest rules toward specific contestants in order to further their prime objective. We derive the optimal bias of the contest rule for a contest administrator, who is interested in maximizing the total efforts expended in the contest. The solution is obtained in closed form for a widely used class of n-person contest games. Setting the optimal bias has important implications: (i) there is never exclusion of strong players, instead there is (endogenously induced) inclusion of weak contestants; (ii) the contest administrator will optimally level the playing field by encouraging weak contestants, but he will not equalize the contestants’ chances unless they are identical; and (iii) at least three contestants will be active in equilibrium of the optimal contest, irrespective of heterogeneity.     

Investment coordination in network industries: the case of electricity grid and electricity generation

Liberalization of network industries frequently separates the network from the other parts of the industry. This is important in particular for the electricity industry where private firms invest into generation facilities, while network investments usually are controlled by regulators. We discuss two regulatory regimes. First, the regulator can only decide on the network extension. Second, she can additionally use a “capacity market” with payments contingent on private generation investment. For the first case, we find that even absent asymmetric information, a lack of regulatory commitment can cause inefficiently high or inefficiently low investments. For the second case, we develop a standard handicap auction which implements the first best under asymmetric information if there are no shadow costs of public funds. With shadow costs, no simple mechanism can implement the second best outcome.