557 research outputs found

    Sustainable Climate Treaties

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    We examine a global refunding scheme for mitigating climate change. Countries pay an initial fee into a global fund that is invested in long-run assets. In each period, part of the fund is distributed among the participating countries in relation to the emission reductions they have achieved in this period. We identify two possible types of sustainable treaty. A first-best sustainable treaty involves varying amounts of refunded wealth and a minimal amount of initial fees inducing socially desirable abatement efforts in each period. In a secondbest sustainable treaty with only two parameters – optimally selected initial fees and constant refunds equal to the interest earned on the fund – the stock of greenhouse gases converges to the socially optimal stock. Finally, we suggest ways for countries to raise money for the payment of initial fees that are neutral to tax payers and international capital markets.climate change mitigation, refunding scheme, international agreements, sustainable treaty

    Teacher professionalisation tools for developing and arranging OER: Studying the WikiWijs portal

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    Background: Wikiwijs (2009-2016) ran as national initiative by the Dutch Ministry of Education to stimulate usage of free and open digital learning material. It aimed to develop an e-learning platform where teachers (in all sectors, going from primary to tertiary education) can both search, find and assess existing as well as develop, arrange and place new digital learning materials. Our paper presents the results of studies that examined the needs and tools required by teachers that want to develop and arrange such new digital materials. It thus provides valuable input when deciding on the policy and strategy for OER (Open Educational Resources). Method: The core of the paper is an empirical study we carried out to further determine the needs and tools for more didactical professionalisation. This type of support and existing OER will have to be provided through the ‘Wikiwise professionalisation portal’. In order to better functionally design the ‘professionalisation portal’ for Wikiwijs we have carried out both desk research and an additional survey study. We carried out desk research into most relevant, existing studies that (partially) dealt with this issue, and carried out another - more recent and more tailored - survey study that also questioned the needs and preferences for using digital OER in the future. A total of 347 teachers from various sectors filled in a structured questionnaire. Results: We found that there is still a long way to go for schools to effectively facilitate their teachers in learning to effectively use and apply digital OER in their daily practice. In this respect, primary education schools are already making good efforts integrating professionalisation in school innovation. Besides technical support, special attention seems to be needed for ‘pedagogical modelling’ when teachers want to combine OER into meaningful education (e.g. continuous learning lines or curricula), an approach followed instigated by the LO (Learning Objects) movement in the past. Older and more experienced teachers seem to fall a bit behind using ICT and OER

    Design of Cueing in Multimedia Practicals

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    Computer programs aimed at the acquisition and application of problem-solving skills are referred to as multimedia practicals. Both instructional guidelines and empirical data on necessary support for learners, studying such competence-based learning programs, are sparse. This thesis describes a literature study and a series of experimental studies into cueing, formats of cognitive feedback which provide effective process support in multimedia practicals. The studies focus on worked-out examples and process worksheets as promising cueing formats to support law students learning to systematically prepare and hold a plea in various authentic situations. As a result of this research, the thesis presents a theoretical model, guidelines and practical implications for the design and use of cueing in multimedia practicals

    Feedback model to support designers of blended learning courses

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    Although extensive research has been carried out, describing the role of feedback in education, and many theoretical models are yet available, procedures and guidelines for actually designing and implementing feedback in practice have remained scarce so far. This explorative study presents a preliminary six-phase design model for feedback (6P/ FB-model) in blended learning courses. Each phase includes leading questions and criteria that guide the designer. After describing the model, we report research into the usability and quality of draft versions of this model. Participants in both a small usability pilot and an expert appraisal survey rated and commented on the model. We conclude that the overall quality of the model was perceived as sufficient, although experts recommended major revisions before the model could actually be used in daily practice

    Building communities for the exchange of learning objects: theoretical foundations and requirements

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    In order to reduce overall costs of developing high-quality digital courses (including both the content, and the learning and teaching activities), the exchange of learning objects has been recognized as a promising solution. This article makes an inventory of the issues involved in the exchange of learning objects within a community. It explores some basic theories, models and specifications and provides a theoretical framework containing the functional and non-functional requirements to establish an exchange system in the educational field. Three levels of requirements are discussed. First, the non-functional requirements that deal with the technical conditions to make learning objects interoperable. Second, some basic use cases (activities) are identified that must be facilitated to enable the technical exchange of learning objects, e.g. searching and adapting the objects. Third, some basic use cases are identified that are required to establish the exchange of learning objects in a community, e.g. policy management, information and training. The implications of this framework are then discussed, including recommendations concerning the identification of reward systems, role changes and evaluation instruments

    A promising biotechnical approach to pest management of the western corn rootworm in Illinois maize fields shielded with a MCA kairomone baited trap line

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    The leaf beetle Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), (D.v.v.), also called the western corn rootworm, is endemic to the New World and ranks among the top ten insect pests in worldwide grain production. D.v.v. causes annual damages of 1 billion US Dollars and is a notoriously difficult insect pest to control and manage, as entomological history of the past 50 years amply demonstrates (METCALF 1986). Considering recent emphasis on environmentally compatible and sustainable management strategies, entomologists and practitioners are encouraged to pay increased attention to novel approaches such as biotechnial methods which today are characterized by preferential use of signal compounds. Fortunately, both insect and plants provide a wide variety of such natural resources. In the case of D.v.v., sex pheromonesand plant kairomones as specific attractants and management tools are relatively well investigated through numerous contributions by GUSS et al. (1982), METCALF & METCALF (1992), METCALF (1994) and many recent publications on the advance and spread of D.v.v. within Europe (BERGER 1995-2004, HUMMEL 2003). Principle of MSD method: In this paper, the plant kairomone 4-methoxycinnamaldehyde (MCA), a specific attractant for D.v.v., is being used as a tool within the newly proposed "MSD" strategy. It combines a two pronge approach consisting as the well known mass trapping with the novel shielding and deflecting, called in short "diversion" and introduced here for the first time. An invisible “curtain” or “fence” of MCA vapor released from a MCA trap line establishes a behavioral barrier which the flying beetles cannot easily pass without being 1. either caught in one of the high capacity traps or 2. being diverted elsewhere. The net effect is a significant reduction in adult population density and oviposition within the MCA treated field as compared to an untreated control field. These effects can be experimentally measured by 1. adult beetle counts on maize plants, 2. by counts in independent monitoring traps baited with the D.v.v. sex pheromone, and 3. by egg counts taken in soil samples.Umweltgerechter und nachhaltiger Pflanzenschutz erfordert eine Vielzahl verschiedener Strategien zum Management von Schadinsekten auf ihren Wirtspflanzen. Insekten- und pflanzeneigene Signalstoffe sowie ihre synthetischen Analoga bieten einen nahezu unerschöpflichen Vorrat spezifischer Lockwirkungen und Interventionsmöglichkeiten an, der bisher leider nur unzureichend genutzt wird. KĂŒrzliche Entdeckungen sowohl neuer Kairomon-Lockstoffe als auch neuer Verfahrensschritte fĂŒr das Management des Westlichen Maiswurzelbohrers Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) (D.v.v.) erweitern das Spektrum anwendbarer Management- Optionen fĂŒr diesen schwer bekĂ€mpfbaren SchĂ€dling im nordamerikanischen Maisanbau. Seit seiner Einschleppung nach Europa (ČAMPRAG & BAČA 1995) wird D.v.v. neuerdings auch zunehmend zum ProblemschĂ€dling an Mais in Europa. Die neue "MSD"-Technik besteht aus einer Kombination von Massenabfang ("mass trapping"), Abschirmung ("shielding") und Umlenkung ("diversion") der BlattkĂ€fer. Fallen hoher FangkapazitĂ€t, die das Kairomon 4-Methoxyzimtaldehyd (MCA) und Cucurbitacin- Pulver als fraßfördernden Stoff enthalten, können bei Aufstellung als "Fallenzaun" relativ geringer Dichte die KĂ€fer so umlenken, dass zwischen den beiden Seiten dieses Zauns eine unsichtbare Geruchs-Barriere entsteht. Diese fĂŒhrt zu einer messbaren und signifikanten Verminderung der KĂ€ferzahl zwischen MCA behandelten Feldabschnitten gegenĂŒber ihren unbehandelten Kontrollen. In 0,27 ha bzw. 0,12 ha großen Maisversuchsfeldern der Standorte Urbana und Champaign des US-Staates Illinois ließen sich wĂ€hrend der Monate August und September 2003 und 2004 nach MCA-Behandlung gegenĂŒber Kontrollen deutliche und signifikante Verminderungen von D.v.v. an Hand dreier Kriterien nachweisen: 1. KĂ€ferzahlen auf Maispflanzen innerhalb des "MSD-Feldes", 2. KĂ€ferzahlen in Sexuallockstoff-Fallen im MSD Feld und 3. die Zahl abgelegter D.v.v.-Eier im Boden des MSD Feldes nehmen ab. Der beobachtete Effekt lĂ€ĂŸt sich nicht allein auf die Populationsverminderung infolge hoher Abfangzahlen zurĂŒckfĂŒhren. Es gibt darĂŒber hinaus einen Abschirm- und Umlenkeffekt, dessen sinnes- und verhaltensphysiologische Mechanismen zusĂ€tzliche kĂŒnftige Erforschungen erforderlich machen

    Leidt gamen wel tot leren?

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    Hummel, H. G. K., & Meijrink, L. (2008). Leidt gamen wel tot leren? [Does gaming lead to learning?] 12-18: Het VAKblad voor het voortgezet onderwijs, 9, 18-19.Omdat games aansluiten op de belevingswereld van jongeren, is te verwachten dat ze positief werken op de motivatie om te leren. Maar de ontwikkeling van games voor het onderwijs is vaak duur en ingewikkeld. Bovendien is er is nog niet veel onderzoek gedaan naar de daadwerkelijke leereffecten van onderwijsgames

    Retrospective cognitive feedback for progress monitoring in serious games

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    Although the importance of cognitive feedback in digital serious games (DSG) is undisputed, we are facing some major design challenges. First of all, we do not know to which extend existing research guidelines apply when we stand the risk of cognitive feedback distorting the delicate balance between learning and playing. Unobtrusive cognitive feedback has to be interspersed with gameplay. Secondly, many effective solutions for providing cognitive feedback we do know might simply be too costly. To face both challenges, this study offers an efficient approach for providing unobtrusive and retrospective cognitive feedback in DSG. This approach was applied onto a game where feedback messages were triggered via simple rules about learners’ questioning behaviour on four dimensions. We found the experimental condition including such retrospective cognitive feedback (RCF) to yield better learning outcomes while maintaining similar motivation. Keyword

    Diabrotica virgifera virgifera LeConte in confrontation mood : simultaneous geographical and host spectrum expansion in southeastern Slovenia

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    Diabrotica virgifera virgifera LeConte, in its original North American habitat also known as western corn rootworm beetle, actively continues its expansion to new territories and uses Homo sapiens as its prime vector. It took only 15 years to spread to and occupy the southeastern and central parts of Europe, so far with the exception of Denmark where it has not been documented as of 2007. Economic thresholds have been reached and surpassed only in Southeast European countries like Slovakia, Hungary, Serbia, Eastern Croatia, Romania and Northern Italy. But both, the area affected and the severity of symptoms are increasing. Model calculations by a number of authors (Baufeld & Enzian, 2005 a and b; Hongmei Li & al. 2006, CLIMEX model) indicate a definitive propensity of D. v. virgifera to expand its currently occupied territory to regions with moderate temperatures and Zea mays cultivation. East Africa and Eastern Asia are included in the list of potential candidates for future inadvertent introduction. In most discussions it is tacitly and erroneously assumed that Z. mays is the only or the only important host of D. v. virgifera. Our recent observations in Eastern Slovenia on the oil pumpkin Cucurbita pepo indicate, however, that this simplifying assumption is notlonger strictly valid. It has to be modified in light of new evidence. Here, we report a few field experiments conducted in August of 2006 clarifying the host status of C. pepo in a European country.Diabrotica virgifera virgifera LeConte (Coleoptera: Chysomelidae), im deutschsprachigen Raum als Westlicher Maiswurzelbohrer bekannt, ist ein von der Neuen Welt nach Europa eingeschleppter SchĂ€dling. Er gelangte in mindestens drei EinwanderungsschĂŒben, die durch molekulargenetische Untersuchungen unterscheidbar sind, nach Europa. Innerhalb der letzten eineinhalb Jahrzehnte wurde, mit Ausnahme von DĂ€nemark, die gesamte FlĂ€che SĂŒdost- und Zentraleuropas vom KĂ€fer besiedelt. In mehreren osteuropĂ€ischen LĂ€ndern ist die ökonomische Schadensschwelle bereits ĂŒberschritten. Bis 2006 galt Zea mays als einzige bekannte europĂ€ische Wirtspflanze. Allerdings deuten neueste Beobachtungen in Ostslowenien vom August 2006 auf kleine Zahlen von KĂ€fern am ÖlkĂŒrbis Cucurbita pepo und damit auf eine Ausdehnung des Wirtsspektrums von D. v. virgifera hin. Der KĂ€fer tritt in kleinen Zahlen als Besucher von ÖlkĂŒrbisblĂŒten mit einer HĂ€ufigkeit von 0,1 % auf. Er ist aber auch in geringer HĂ€ufigkeit in Kairomon- und Pheromonfallen in ÖlkĂŒrbisfeldern sĂŒdlich von Gaberje in Ostslowenien anzutreffen. Dieses Ergebnis stellt den zukĂŒnftigen Wert des Fruchtwechsels in Frage, der bisher als eine der wirksamsten und nachhaltigsten Methoden des integrierten Pflanzenschutzes galt
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