Browsing while reading: effects of instructional design and learners' prior knowledge

One of the key reasons that multimedia, and particularly hypertext systems, are gaining in importance is that they inspire hopes of optimizing learners' processes of knowledge construction. The present study is concerned with the respective influence of individual learner variables (i.e. particularly domain‐specific prior knowledge) on the use of different design attributes. Thirty‐six university students worked through a hierarchically structured two‐part hypertext about the psychology of memory under two experimental browsing conditions (reduced versus free browsing). Results show that deeper‐level comprehension (i.e. structural knowledge) was predicted by the interaction of experimental condition and prior knowledge, but that simply retaining facts was not. Participants with low prior knowledge performed better on the comprehension test if they had worked on the version with reduced access. Moreover, the version with reduced access helped to reduce feelings of disorientation. The measure of disorientation also appeared to be closely linked with the individual's computer experience, self‐concept of computer ability and subject‐related interest. The main implications for educational practice relate to the design of an adaptive multimedia and hypertext learning system and the successful learning with it

A Bramble-Pasciak conjugate gradient method for discrete Stokes equations with random viscosity

We study the iterative solution of linear systems of equations arising from stochastic Galerkin finite element discretizations of saddle point problems. We focus on the Stokes model with random data parametrized by uniformly distributed random variables and discuss well-posedness of the variational formulations. We introduce a Bramble-Pasciak conjugate gradient method as a linear solver. It builds on a non-standard inner product associated with a block triangular preconditioner. The block triangular structure enables more sophisticated preconditioners than the block diagonal structure usually applied in MINRES methods. We show how the existence requirements of a conjugate gradient method can be met in our setting. We analyze the performance of the solvers depending on relevant physical and numerical parameters by means of eigenvalue estimates. For this purpose, we derive bounds for the eigenvalues of the relevant preconditioned sub-matrices. We illustrate our findings using the flow in a driven cavity as a numerical test case, where the viscosity is given by a truncated Karhunen-Lo\`eve expansion of a random field. In this example, a Bramble-Pasciak conjugate gradient method with block triangular preconditioner outperforms a MINRES method with block diagonal preconditioner in terms of iteration numbers.Comment: 19 pages, 1 figure, submitted to SIAM JU

Pitfalls and Opportunities in Knowledge Sharing - Experiences from a research capacity building project in Central America

A number of attempts have been made in the North to assist in the formation of independent research capacities in the South by establishing knowledge sharing through North-South research collaboration. One such attempt was initiated by Danida through its programme for Enhancement of Research Capacity (ENRECA). Aalborg University was approached by the National University of Costa Rica to make a joint research venture within the field of sustainable development. The project got a Central American (CA) regional perspective by including participants from Nicaragua and El Salvador. The project was titled Sustainable Development Strategies for Central America (SUDESCA) and aimed at support of relevant CA research activities, including the formation of adequate organizational setups that would eventually sustain forthwith. The project focused on two theoretical themes, i.e. the National Systems of Innovation and the Social Construction of Technology approaches. In this paper the CA universities are viewed as important sub-systems of the respective national systems of innovation. Thus, the following is an analysis of the institutional sustainability of the research capacity of universities perceived as parts of the national systems of innovation. To what extent did the knowledge transfer and exchange as well as the organizational capacity building efforts succeed? What were the main pitfalls and opportunities experienced? What did the Aalborg team learn about its own research capacity set-up? Our overall conclusion is that it is a mistake to assume that research capacity may be more or less directly transferred from the North to the South. Research capacity existing in the North has to be carefully adapted to the specific conditions where it may be expected to be useful.Innovation system, knowledge adaption, Central America

The Economic Effects of Direct Democracy – A First Global Assessment

This is the first study that assesses the economic effects of direct democratic institutions on a cross country basis. Its results are based on up to six new measures produced to reflect the legislative basis for using direct democratic institutions as well as their factual use. In addition, a more general overall indicator is used. On the basis of these two different data sets only some of the results of the former intra-country studies are confirmed. An analysis based on the more general democracy index for 87 countries shows that a higher degree of direct democracy leads to lower budget deficits and higher government effectiveness. The effects on government expenditure, corruption and productivity have the expected signs but do not reach conventional levels of significance. A more fine grained analysis for a cross section of 88 countries based on the second data set shows that institutional detail matters a great deal. In particular, the mere possibility of drawing on direct-democratic institutions is often not sufficient to induce significant effects whereas the frequency of their factual use has a number of substantive effects on economic variables.direct democracy, economic effects of constitutions, positive constitutional economics

Security Mechanisms for Workflows in Service-Oriented Architectures

Die Arbeit untersucht, wie sich Unterstützung für Sicherheit und Identitätsmanagement in ein Workflow-Management-System integrieren lässt. Basierend auf einer Anforderungsanalyse anhand eines Beispiels aus der beruflichen Weiterbildung und einem Abgleich mit dem Stand der Technik wird eine Architektur für die sichere Ausführung von Workflows und die Integration mit Identitätsmanagement-Systemen entwickelt, die neue Anwendungen mit verbesserter Sicherheit und Privatsphäre ermöglicht

Exposure of Larvae of the Solitary Bee Osmia bicornis to the Honey Bee Pathogen Nosema ceranae Affects Life History

Wild bees are important pollinators of wild plants and agricultural crops and they are threatened by several environmental stressors including emerging pathogens. Honey bees have been suggested as a potential source of pathogen spillover. One prevalent pathogen that has recently emerged as a honey bee disease is the microsporidian Nosema ceranae. While the impacts of N. ceranae in honey bees are well documented, virtually nothing is known about its effects in solitary wild bees. The solitary mason bee Osmia bicornis is a common pollinator in orchards and amenable to commercial management. Here, we experimentally exposed larvae of O. bicornis to food contaminated with N. ceranae and document spore presence during larval development. We measured mortality, growth parameters, and timing of pupation in a semi-field experiment. Hatched individuals were assessed for physiological state including fat body mass, wing muscle mass, and body size. We recorded higher mortality in the viable-spore-exposed group but could only detect a low number of spores among the individuals of this treatment. Viable-spore-treated individuals with higher head capsule width had a delayed pupation start. No impact on the physiological status could be detected in hatched imagines. Although we did not find overt evidence of O. bicornis infection, our findings indicate that exposure of larvae to viable N. ceranae spores could affect bee development

Die Fehlbewertung durch das Stuttgarter Verfahren: eine Sensitivitätsanalyse der Werttreiber von Steuer- und Marktwerten

This paper focuses on firm valuation for tax purposes of non-listed company shares and its sensitivity towards different market conditions. Since the value of a private company cannot be observed on the stock market the value has to be estimated. Due to uncertainty, expected future profits may not serve as a tax base. Therefore, in Germany e.g., a tax value is derived on the basis of a combination of net assets and historic profits - the so called Stuttgart Method. A Discounted Cash Flow Model, as a generally accepted method of firm valuation, is used as a proxy for the market value. In this analysis a simulation quantifies the gap between both approaches for firms of six different industries. Thereby, we find out which industries are discriminated and which are subsidized by taxation. Furthermore, the sensitivity of the value gap with regard to the relevant value drivers (cost of capital, financial structure, corporate tax rates, growth, and timing effects) is investigated. In the basic setting the value is only 31,3% to 92,4% of the market value. Thus, tax values lead to a severe undervaluation of the company. Moreover, the span of the relations shows that the firms are treated unequally. Variations show that overvaluations are also likely to be observed. These results are helpful to design a true and fair tax base. --firm valuation,gift tax,inheritance tax,tax value,sensitivity analysis,value gap,discounted cash flow