1,525 research outputs found
Wavelets Applied to the Detection of Point Sources of UHECRs
In this work we analyze the effect of smoothing maps containing arrival
directions of cosmic rays with a gaussian kernel and kernels of the mexican hat
wavelets of orders 1, 2 and 3. The analysis is performed by calculating the
amplification of the signal-to-noise ratio for several anisotropy patterns
(noise) and different number of events coming from a simulated source (signal)
for an ideal detector capable of observing the full sky with equal probability.
We extend this analysis for a virtual detector located within the array of
detectors of the Pierre Auger Observatory, considering an acceptance law.Comment: 9 pages, 8 figures. Proceedings of the Young Researchers Meeting,
2010. Available in:
http://www.ifi.unicamp.br/physicae/ojs-2.1.1/index.php/physicae/article/view/191;
Physicae, Proceedings of the Young Researchers Meeting, Vol 1, 201
Perspectives On Software-defined Networks: Interviews With Five Leading Scientists From The Networking Community
Software defined Networks (SDNs) have drawn much attention both from academia and industry over the last few years. Despite the fact that underlying ideas already exist through areas such as P2P applications and active networks (e.g. virtual topologies and dynamic changes of the network via software), only now has the technology evolved to a point where it is possible to scale the implementations, which justifies the high interest in SDNs nowadays. In this article, the JISA Editors invite five leading scientists from three continents (Raouf Boutaba, David Hutchison, Raj Jain, Ramachandran Ramjee, and Christian Esteve Rothenberg) to give their opinions about what is really new in SDNs. The interviews cover whether big telecom and data center companies need to consider using SDNs, if the new paradigm is changing the way computer networks are understood and taught, and what are the open issues on the topic.
Requirements for a Nutrition Education Demonstrator
[Context and Motivation] Development of innovative ICT-based applications is a complex process involving collaboration of all relevant disciplines. This complexity arises due to differences in terminology, knowledge and often also the ways of working between developers in the disciplines involved. [Question/problem] Advances in each discipline bring a rich design environment of theories, models, methods and techniques. Making a selection from these makes the development of distributed applications very challenging, often requiring a holistic approach to address the needs of the disciplines involved. This paper describes early stage requirements acquisition of a mobile nutrition education demonstrator which supports overweight persons in adopting healthier dietary behaviour. [Principal idea/results] We present a novel way to combine and use known requirements acquisition methods involving a two stage user needs analysis based on scenarios which apply a theory-based model of behavioural change and are onstructed in two phases. The first phase scenarios specify an indicative description reflecting the use of the transtheoretical model of behavioural change. In the second phase, a handshake protocol adds elements of optative system-oriented descriptions to the scenarios such that the intended system can support the indicative description. [Contribution] The holistic and phased approach separates design concerns to which each of the disciplines contributes with their own expertise and domain principles. It preserves the applied domain principles in the design and it bridges gaps in terminology, knowledge and ways of working
Molybdenite as a rhenium carrier : first results of a spectroscopic approach using synchrotron radiation
The chemical and physical properties of rhenium render it a highly demanded metal for advanced applications in important industrial fields. This very scarce
element occurs mainly in ores of porphyry copper-molybdenum deposits associated with the mineral molybdenite, MoS2, but it has also been found in granite
pegmatites and quartz veins as well as in volcanic gases. Molybdenite is a typical polytype mineral which crystal structure is based on the stacking of [S-Mo-S]
with molybdenum in prismatic coordination by sulphide anions; however, it is not yet clearly established if rhenium ions replace Mo4+ cations in a disordered
way or else, if such replacement gives rise to dispersed nanodomains of a rhenium-rich phase. As a contribution to clarify this question, an X-ray absorption
spectroscopy (XANES) study using synchrotron radiation was performed at the Re L3-edge of rhenium-containing molybdenite samples. Obtained results are
described and discussed supporting the generally accepted structural perspective that rhenium is mainly carried by molybdenite through the isomorphous
replacement of Mo, rather than by the formation of dispersed Re-specific nanophase(s)
Renormalized Classical Theory of Quantum Magnets
We derive a renormalized classical spin (RCS) theory for quantum
magnets by constraining a generalized classical theory that includes all
multipolar fluctuations to a reduced CP phase space of dipolar SU()
coherent states. When the spin Hamiltonian is linear in the
spin operators for each lattice site , the RCS
Hamiltonian coincides with the usual classical model
. In the presence
of non-linear terms, however, the RCS theory is more accurate than
. For the many materials modeled by spin Hamiltonians with
(non-linear) single-ion anisotropy terms, the use of the RCS theory is
essential to accurately model phase diagrams and to extract the correct
Hamiltonian parameters from neutron scattering dataComment: 5 pages, 1 figure
Iron oxide doped boron nitride nanotubes: structural and magnetic properties
A first-principles formalism is employed to investigate the interaction of
iron oxide (FeO) with a boron nitride (BN) nanotube. The stable structure of
the FeO-nanotube has Fe atoms binding N atoms, with bond length of roughly
2.1 \AA, and binding between O and B atoms, with bond length of 1.55 \AA.
In case of small FeO concentrations, the total magnetic moment is
(4) times the number of Fe atoms in the unit cell and it is
energetically favorable to FeO units to aggregate rather than randomly bind to
the tube. As a larger FeO concentration case, we study a BN nanotube fully
covered by a single layer of FeO. We found that such a structure has square FeO
lattice with Fe-O bond length of 2.11 \AA, similar to that of FeO bulk, and
total magnetic moment of 3.94 per Fe atom. Consistently with
experimental results, the FeO covered nanotube is a semi-half-metal which can
become a half-metal if a small change in the Fermi level is induced. Such a
structure may be important in the spintronics context.Comment: 10 pages, 3 figure
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