129 research outputs found
Information Literacy Needs Open Access or: Open Access is not Only for Researchers
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?
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
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
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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