Identification of a nonlinear dynamic biological model using the dominant parameter selection method

The identification of nonlinear models sometimes encounters problems because of the limited amount of available measurements in combination with a large number of uncertain model parameters to be identified. E.g., the determination of the chemical composition of a lettuce crop is a rather expensive procedure; thus the number of experimental measurements is limited. As a result, the number of parameters of the dynamic model that can be successively identified is also limited, and the subset of the parameters to be identified must be chosen in a reasonable way.Parameter estimation for an extended nonlinear three-state model for lettuce growth in greenhouses is presented in this paper. The varying structural nitrogen concentration and water contents are the new elements included in the model. The dominant parameter selection (DPS) method was used to select a suitable set of identifiable parameters. The resulting calibrated model predicts quite well the experimental data which also include observations with severe nitrogen stress.     

Superstar effects on royalty income in a performing rights organization

This paper examines the economic accomplishments of individual members in a Performing Rights Organization (PRO), sometimes referred to as a Performing Rights Society. Today, there is the growing importance of intellectual property and copyright protection for authors and creators of literary, dramatic, musical, artistic and other intellectual works. The digital age has placed added pressure on songwriters, lyricists and composers in their ability to derive economic benefits from their intellectual creativity in the form of a copyright. Copyright laws protect and enable the creation of music by allowing authors and composers to license the control and use of their creations, and receive compensation in the form of royalty payments for their work. The PROs license, collect and distribute royalty payments for non-dramatic public performances of copyrighted musical works created and owned by its members or affiliates. In this paper, skewness and heavy tail of returns in the form of member royalty payments are estimated using the skew-normal and skew-t distributions in a parametric approach. We found strong evidence of the so-called ‘superstar effect’ in which the average royalty payment made by a PRO is still dominated by extreme outcomes, and relatively few members earned a substantial share of royalty payments from blockbuster hits that have endured over time. There is little evidence of smaller niche members dominating or replacing the ‘superstars.’ Economists and others will benefit from this empirical study which emphasizes a new understanding of the music industry from a PRO, member royalty payment and performance copyright perspective.     

The Academic Spin-Offs as an Engine of Economic Transition in Eastern Europe. A Path-Dependent Approach

The paper questions some of the premises in studying academic spin-offs in developed countries, claiming that when taken as characteristics of ‘academic spin-offs per se,’ they are of little help in understanding the phenomenon in the Eastern European countries during the transitional and post-transitional periods after 1989. It argues for the necessity of adopting a path-dependent approach, which takes into consideration the institutional and organisational specificities of local economies and research systems and their evolution, which strongly influence the patterns of spin-off activity. The paper provides new findings and original arguments in support of Balazs’ seminal theses (Balazs 1995, 1996) about the emergence of academic spin-offs during the early transition. It reveals key economic and policy mechanisms bearing on academic entrepreneurship in Eastern Europe, such as the tensions between economic and political nomenclatures of former Communist Parties, where the dismantling or preservation of the power of political nomenclature resulted in different patterns of development—rapid reforms in the ‘first wave’ of EU accession countries or the establishment of rent-seeking and assets-stripping economies in countries like Bulgaria and Romania, making the transition period especially difficult. In the latter, a specific economic environment emerged, unknown in Western Europe and in the ‘champions’ of transition—such as suppression of the authentic entrepreneurship in a number of economic sectors, disintegration of corporate structures, etc. Thus, the paper reveals the common ground behind the two conflicting tendencies in post-socialist academic spin-offs, partially outlined in other research (Simeonova 1995; Pavlova 2000): as an authentic form of academic entrepreneurship grasping the opportunities opened up by the economic crisis and compensating failures in science and technology policy on the one hand, and as specific rent-seeking strategy draining valuable public assets on the other (the latter, in turn, boosting the negative attitudes in local scientific communities). The paper provides new findings about the evolution of the academic spin-offs in Bulgaria along the two polar trends and their positive and negative repercussions on parent research institutions. The results were achieved in the PROKNOW Project, EC 6th Framework Program.     

A plea for research on lay literacy

This paper distinguishes scribal literacy, the ability to read and write, from lay literacy, the pervasive set of assumptions taken for granted by readers and non-readers who participate in a literate society. The task for the study of literacy is to uncover and examine these assumptions. The route to the discovery of these literate assumptions is through a consideration of the relations between the vernacular and the literate forms of language.     

Best-bet channels for integrated soil fertility management communication and dissemination along the agricultural product value-chain: a comparison of northern Ghana and western Kenya

Purpose: The aim of this paper is to comparatively assess the most suitable channels for dissemination of agricultural innovations along the entire information value chain.

Design/Methodology/Approach: We calculated information scores to measure channel preference from a randomly selected sample of farmers: 285 in Tamale, Ghana and 300 in Kakamega, Kenya. Using t-tests we compared the information score differences of different channels between farmers who adopted Integrated Soil Fertility Management and those who did not.

Findings: The highest information scores were observed for radio along the entire value chain for both locations. However, farmers in Tamale prefered interpersonal channels for processing information. Radio and farmer field days had the highest rankings for production information at both locations. Radio, workshops and interpersonal channels (traders and neighbours/friends/relatives) were best-bet channels for marketing and procesing information.

Practical implication: Extension agents should place more emphasis on channels such as radio, farmer field days, and workshops as they may offer more efficient delivery of information packages at all levels, whilst recognizing the central role of interpersonal channels.

Theoretical implication: The nexus between the uses and gratification, adoption, diffusion of innovations theories and the collaborative communication theory on one hand, and the agricultural product value chain framework on the other, is highlighted. Farmers’ preference for information channels is not predicated on the stage of the value chain.

Originality/Value: In the current context of weak agricultural knowledge and innovation systems in African agriculture, agricultural producers are poorly informed about the current innovations. This study furnishes empirical evidence on the best-bet information channels to be used by extension workers and change agents to disseminate and communicate system innovations.