695 research outputs found

    All about that - a URI profiling tool for monitoring and preserving linked data

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    All About That (AAT) is a URI Profiling tool which allows users to monitor and preserve Linked Data in which they are interested. Its design is based upon the principle of adapting ideas from hypermedia link integrity in order to apply them to the Semantic Web. As the Linked Data Web expands it will become increasingly important to maintain links such that the data remains useful and therefore this tool is presented as a step towards providing this maintenance capability

    The ferroelectric Mott-Hubbard phase of organic (TMTTF)2X conductors

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    We present experimental evidences for a ferro-electric transition in the family of quasi one- dimensional conductors (TMTTF)2X. We interpret this new transition in the frame of the combined Mott-Hubbard state taking into account the double action of the spontaneous charge disproportionation on the TMTTF molecular stacks and of the X anionic potentials

    Overview of Future NASA Tether Applications

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    The groundwork has been laid for tether applications in space. NASA has developed tether technology for space applications since the 1960's. Important recent milestones include retrieval of a tether in space (TSS-1, 1992), successful deployment of a 20-km-long tether in space (SEDS-1, 1993), and operation of an electrodynamic tether with tether current driven in both directions-power and thrust modes (PMG, 1993). Various types of tethers and systems can be used for space transportation. Short electrodynamic tethers can use solar power to 'push' against a planetary magnetic field to achieve propulsion without the expenditure of propellant. The planned Propulsive Small Expendable Deployer System (ProSEDS) experiment will demonstrate electrodynamic tether thrust during its flight in early 2000. Utilizing completely different physical principles, long non-conducting tethers can exchange momentum between two masses in orbit to place one body into a higher orbit or a transfer orbit for lunar and planetary missions. Recently completed system studies of this concept indicate that it would be a relatively low-cost in-space asset with long-term multi-mission capability. Tethers can also be used to support space science by providing a mechanism for precision formation flying and for reaching regions of the upper atmosphere that were previously inaccessible

    Wrinkles and creases in the bending, unbending and eversion of soft sectors

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    We study what is clearly one of the most common modes of deformation found in nature, science and engineering, namely the large elastic bending of curved structures, as well as its inverse, unbending, which can be brought beyond complete straightening to turn into eversion. We find that the suggested mathematical solution to these problems always exists and is unique when the solid is modelled as a homogeneous, isotropic, incompressible hyperelastic material with a strain-energy satisfying the strong ellipticity condition. We also provide explicit asympto-tic solutions for thin sectors. When the deformations are severe enough, the compressed side of the elastic material may buckle and wrinkles could then develop. We analyse in detail the onset of this instability for the Mooney-Rivlin strain energy, which covers the cases of the neo-Hookean model in exact non-linear elasticity and of third-order elastic materials in weakly non-linear elasticity. In particular the associated theoretical and numerical treatment allows us to predict the number and wavelength of the wrinkles. Guided by experimental observations we finally look at the development of creases, which we simulate through advanced finite element computations. In some cases the linearised analysis allows us to predict correctly the number and the wavelength of the creases, which turn out to occur only a few percent of strain earlier than the wrinkles

    Target discovery focused approaches to overcome bottlenecks in the exploitation of antimycobacterial natural products

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    Tuberculosis is a major global health hazard. The search for new antimycobacterials has focused on such as screening combinational chemistry libraries or designing chemicals to target predefined pockets of essential bacterial proteins. The relative ineffectiveness of these has led to a reappraisal of natural products for new antimycobacterial drug leads. However, progress has been limited, we suggest through a failure in many cases to define the drug target and optimize the hits using this information. We highlight methods of target discovery needed to develop a drug into a candidate for clinical trials. We incorporate these into suggested analysis pipelines which could inform the research strategies to accelerate the development of new drug leads from natural products

    Propulsive Small Expendable Deployer System (ProSEDS) space experiment

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76480/1/AIAA-1998-4035-142.pd

    Doing Real Time Research: Opportunities and Challenges

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    This paper emerges out of a programme of workshops on Real Time Research, funded by NCRM during 2011-12, which brought together a network of interdisciplinary scholars to discuss the possibilities and challenges of doing research in real time. As well as these discussions, we also engaged in various exercises designed to give us practical experience of doing research in real time. The past, present and future are always brought together in social science methods, contributing to temporally significant modalities of enquiry, such as the ethnographic present, prediction or genealogy. But the workshops were designed to address the implications of the ‘timeliness’ of research in the context of an increasingly digitised and informational culture that allows access to, and creates dependences on, quantities of data gathered from diverse sources, often as soon as they are produced. The main questions we sought to address were: How are the dynamics of an informational society and digital culture transforming the temporality of methods? What opportunities are offered for research by the ongoing expansion of the present? And how can social science make use of the availability of real-time (immediately and continuously accessible) information? This paper explores the opportunities and threats of doing research in real time

    The Propulsive Small Expendable Deployer System Experiment

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    Relatively short electrodynamic tethers can extract orbital energy to 'push' against a planetary magnetic field to achieve propulsion without the expenditure of propellant. The Propulsive Small Expendable Deployer System experiment will use the flight-proven Small Expendable Deployer System (SEDS) to deploy a 5 km bare copper tether from a Delta II upper stage to achieve approximately 0.4 N drag thrust, thus lowering the altitude of the stage. The experiment will use a predominantly 'bare' tether for current collection in lieu of the endmass collector and insulated tether approach used on previous missions. The flight experiment is a precursor to a more ambitious electrodynamic tether upper stage demonstration mission which will be capable of orbit raising, lowering and inclination changes - all using electrodynamic thrust. The expected performance of the tether propulsion system during the experiment is described
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