128 research outputs found

    Information Literacy Needs Open Access or: Open Access is not Only for Researchers

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    The Open Access was initially (blandly) conceived in view not only of researchers but also of lay readers, then this perspective slowly faded out. The Information Literacy movement wants to teach citizens how to arrive at trustable information but the amount of paywalled knowledge is still big. So, their lines of development are somehow complementary: Information Literacy needs Open Access for the citizens to freely access high quality information while Open Access truly fulfils its scope when it is conceived and realized not only for the researchers (an aristocratic view which was the initial one) but for the whole society

    Sustainable development and African local government: can electronic training help build capacities?

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    A recent study carried out by European and African organizations into the potential for electronic distance training (EDT) on sustainability in African local governments concluded that EDT was both 'useful and feasible'. This article reflects on some of the theoretical and practical implications of that study. It focuses on the connection between learning and sustainability and how EDT programmes might be designed and promoted. The paper argues that, while resource issues and poor access to Information and Communication Technologies (ICTs) create considerable constraints and point to the need for policies to improve access, in general the most important factors for successful capacity building relate to the design of learning programmes that take account of the work contexts and skill and capability requirements of those targeted as learners. 'Useful' and 'feasible' depend on (i) how work-based and work-related learning processes are understood and (ii) the conditions to promote learning within African local government. Keywords: Africa; Electronic distance training; Local government; Sustainability; Workplace learnin

    Observation of Quantum Interference in Molecular Charge Transport

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    As the dimensions of a conductor approach the nano-scale, quantum effects will begin to dominate its behavior. This entails the exciting possibility of controlling the conductance of a device by direct manipulation of the electron wave function. Such control has been most clearly demonstrated in mesoscopic semiconductor structures at low temperatures. Indeed, the Aharanov-Bohm effect, conductance quantization and universal conductance fluctuations are direct manifestations of the electron wave nature. However, an extension of this concept to more practical emperatures has not been achieved so far. As molecules are nano-scale objects with typical energy level spacings (~eV) much larger than the thermal energy at 300 K (~25 meV), they are natural candidates to enable such a break-through. Fascinating phenomena including giant magnetoresistance, Kondo effects and conductance switching, have previously been demonstrated at the molecular level. Here, we report direct evidence for destructive quantum interference in charge transport through two-terminal molecular junctions at room temperature. Furthermore, we show that the degree of interference can be controlled by simple chemical modifications of the molecule. Not only does this provide the experimental demonstration of a new phenomenon in quantum charge transport, it also opens the road for a new type of molecular devices based on chemical or electrostatic control of quantum interference

    Interference-based molecular transistors

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    Molecular transistors have the potential for switching with lower gate voltages than conventional field-effect transistors. We have calculated the performance of a single-molecule device in which there is interference between electron transport through the highest occupied molecular orbital and the lowest unoccupied molecular orbital of a single molecule. Quantum interference results in a subthreshold slope that is independent of temperature. For realistic parameters the change in gate potential required for a change in source-drain current of two decades is 20 mV, which is a factor of six smaller than the theoretical limit for a metal-oxide-semiconductor field-effect transistor
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