1,263 research outputs found
Superconducting diamagnetic fluctuations in ropes of carbon nanotubes
We report low-temperature magnetisation measurements on a large number of
purified ropes of single wall carbon nanotubes. In spite of a large
superparamagnetic contribution due to the small ferromagnetic catalytical
particles still present in the sample, at low temperature () and low
magnetic field (), a diamagnetic signal is detectable. This low
temperature diamagnetism can be interpreted as the Meissner effect in ropes of
carbon nanotubes which have previously been shown to exhibit superconductivity
from transport measurements.Comment: 10 pages 3 figure
On the diffraction pattern of C60 peapods
We present detailed calculations of the diffraction pattern of a powder of
bundles of C peapods. The influence of all pertinent structural
parameters of the bundles on the diffraction diagram is discussed, which should
lead to a better interpretation of X-ray and neutron diffraction diagrams. We
illustrate our formalism for X-ray scattering experiments performed on peapod
samples synthesized from 2 different technics, which present different
structural parameters. We propose and test different criteria to solve the
difficult problem of the filling rate determination.Comment: Sumitted 19 May 200
Integrated and dynamical oceanographic data management - IDOD
The goal of the IDOD project was to provide the federal government, the scientific community and other users with an up-to-date tool for collecting, managing and analysing marine scientific data.The resulting âmarine information systemâ is hosted by the Belgian Marine Data Centre (BMDC), a team within the Management Unit of the Mathematical Mode's of the North Sec (MUMM). The BMDC committed itself to keep the IDOD information system alive and evolving. A remote user interface is available online at http:/ /www.mumm.ac.be/ datacentre.The project faced all the aspects of modern scientific data management. A major challenge was to establish a fruitful dialog with the data providers. This has been done through extensive discussions in the Users committee and during bilateral meetings. The topics that have then been clarified range from the principles (in order to write down a standard common âRights and duties" agreement) to the very technical and scientific details, specific to each data set .A substantial effort has been put on the definition of guidelines for ensuring the data quality throughout their way from the field to the data centre. This has resulted, for instance, in the development of a âOn-board registration of samples" computer programme, in a check list of meta-information to document the data or in the definition of a âcommon layout" for reporting data sets to the data centre.On the technical side, the variety and complexity of the data to be stored and made available for further use lead us to elaborate a complex and robust data base scheme, after an in-depth conceptual analysis. The database itself is implemented using the ORACLE technology.In parallel, a set of dedicated analysis and visualisation tools has been developed. They help the users and the data managers to tackle the data in their space and time dimensions and also allow cross-analysis between different parameters.The primary providers of data for the information system were the various teams participating in the (first) Programme for a sustainable development of the North Sea, financed by the Belgian Federal Office for scientific, technical and cultural affairs. These data are being complemented by data from other (earlier) scientific programmes and from governmental surveys.The project has been performed by MUMM, in partnership with the SURFACES laboratory (University of Liege) and the University Centre of Statistics (University of Leuven)
The art of being human : a project for general philosophy of science
Throughout the medieval and modern periods, in various sacred and secular guises, the unification of all forms of knowledge under the rubric of âscienceâ has been taken as the prerogative of humanity as a species. However, as our sense of species privilege has been called increasingly into question, so too has the very salience of âhumanityâ and âscienceâ as general categories, let alone ones that might bear some essential relationship to each other. After showing how the ascendant Stanford School in the philosophy of science has contributed to this joint demystification of âhumanityâ and âscienceâ, I proceed on a more positive note to a conceptual framework for making sense of science as the art of being human. My understanding of âscienceâ is indebted to the red thread that runs from Christian theology through the Scientific Revolution and Enlightenment to the Humboldtian revival of the university as the site for the synthesis of knowledge as the culmination of self-development. Especially salient to this idea is scienceâs epistemic capacity to manage modality (i.e. to determine the conditions under which possibilities can be actualised) and its political capacity to organize humanity into projects of universal concern. However, the challenge facing such an ideal in the twentyfirst century is that the predicate âhumanâ may be projected in three quite distinct ways, governed by what I call âecologicalâ, âbiomedicalâ and âcyberneticâ interests. Which one of these future humanities would claim todayâs humans as proper ancestors and could these futures co-habit the same world thus become two important questions that general philosophy of science will need to address in the coming years
An insulating grid spacer for large-area MICROMEGAS chambers
We present an original design for large area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides an uniform 200 m amplification gap. The uniformity of the amplification gap thickness has been verified under several experimental conditions. The gain performances of the detector are presented and compared to the values obtained with detectors using cylindrical micro spacers. The new design presents several technical and financial advantages
Magneto-mechanically actuated microstructures to efficiently prevent bacterial biofilm formation
Abstract: Biofilm colonisation of surfaces is of critical importance in various areas ranging from indwelling medical devices to industrial setups. Of particular importance is the reduced susceptibility of bacteria embedded in a biofilm to existing antimicrobial agents. In this paper, we demonstrate that remotely actuated magnetic cantilevers grafted on a substrate act efficiently in preventing bacterial biofilm formation. When exposed to an alternating magnetic field, the flexible magnetic cantilevers vertically deflect from their initial position periodically, with an extremely low frequency (0.16 Hz). The cantileversâ beating prevents the initial stage of bacterial adhesion to the substrate surface and the subsequent biofilm growth. Our experimental data on E. coli liquid cultures demonstrate up to a 70% reduction in biofilm formation. A theoretical model has been developed to predict the amplitude of the cantilevers vertical deflection. Our results demonstrate proof-of-concept for a device that can magneto-mechanically prevent the first stage in bacterial biofilm formation, acting as on-demand fouling release active surfaces
A simple but efficient voice activity detection algorithm through Hilbert transform and dynamic threshold for speech pathologies
A simple but efficient voice activity detector based on the Hilbert transform and a dynamic threshold is presented to be used on the pre-processing of audio signals -- The algorithm to define the dynamic threshold is a modification of a convex combination found in literature -- This scheme allows the detection of prosodic and silence segments on a speech in presence of non-ideal conditions like a spectral overlapped noise -- The present work shows preliminary results over a database built with some political speech -- The tests were performed adding artificial noise to natural noises over the audio signals, and some algorithms are compared -- Results will be extrapolated to the field of adaptive filtering on monophonic signals and the analysis of speech pathologies on futures works20th Argentinean Bioengineering Society Congress, SABI 2015 (XX Congreso Argentino de BioingenierĂa y IX Jornadas de IngenierĂa ClĂnica)28â30 October 2015, San NicolĂĄs de los Arroyos, Argentin
Signatures of selection for bonamiosis resistance in European flat oyster (Ostrea edulis):new genomic tools for breeding programs and management of natural resources
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