8,171 research outputs found
A Virtual Observatory Vision based on Publishing and Virtual Data
We would like to propose a vision of the Virtual Observatory where the "killer-app" is seen to be
generalizing and extending the idea of "publication" from the narrow meaning of peer-reviewed
journals. Here, publication ranges from private temporary storage, to group access, to public
access, through to data that supports peer-reviewed Journal papers in perpetuity. The publication
model is further extended by the possibility of Virtual Data -- where only the method of
computation is stored, not necessarily the data itself. Furthermore, virtual data products may
depend on other virtual data products, creating an implicit network of on-demand computation.
This computation may take huge resources, or it may be all within a laptop
Chern numbers and chiral anomalies in Weyl butterflies
The Hofstadter butterfly of lattice electrons in a strong magnetic field is a
cornerstone of condensed matter physics, exploring the competition between
periodicities imposed by the lattice and the field. In this work we introduce
and characterize the Weyl butterfly, which emerges when a large magnetic field
is applied to a three-dimensional Weyl semimetal. Using an experimentally
motivated lattice model for cold atomic systems, we solve this problem
numerically. We find that Weyl nodes reemerge at commensurate fluxes and
propose using wavepackets dynamics to reveal their chirality and location.
Moreover, we show that the chiral anomaly -- a hallmark of the topological Weyl
semimetal -- does not remain proportional to magnetic field at large fields,
but rather inherits a fractal structure of linear regimes as a function of
external field. The slope of each linear regime is determined by the difference
of two Chern numbers in gaps of the Weyl butterfly and can be measured
experimentally in time of flight.Comment: 4 pages, 4 figures + supplementary material, version accepted in
Phys. Rev. B as a Rapid Communicatio
The Production of High-Quality Video for E-Learning
As video capture, editing and transmission capabilities become more accessible, video is increasingly being considered when developing e-learning content. However, the skills required for video production are not commonly part of many e-learning developers backgrounds. This paper presents the experiences of academics from the spatial information sciences when developing high quality video content for an on-line e-learning module in Global Navigation Satellite Systems (GNSS). Video comprises one element of the module and is designed to, as far as possible, address the lack of ‘hands-on’ experience of GNSS equipment and observing procedures. The video element of the module was used by a cohort of post-graduate students at the Technological University of Dublin and the feedback was favourable. While acknowledging its advantages, the authors conclude that the cost, time and complexity of producing high-quality video should not be underestimated. Also, they note that keeping multimedia-rich courses current, particularly in an area of rapid technological change, is a challenge. E-learning course developers considering using video should carry-out both a pedagogical- and a cost-benefit analysis to establish if the inclusion of video is worthwhile. The most important component in producing an active learning experience continues to be the quality of the instructional design and content, not the media itself
THE PRODUCTION OF HIGH-QUALITY VIDEO FOR E-LEARNING
As video capture, editing and transmission capabilities become more accessible, video is increasingly being considered when developing e-learning content. However, the skills required for video production are not commonly part of many e-learning developers backgrounds. This paper presents the experiences of academics from the spatial information sciences when developing high quality video content for an on-line e-learning module in Global Navigation Satellite Systems (GNSS). Video comprises one element of the module and is designed to, as far as possible, address the lack of ‘hands-on’ experience of GNSS equipment and observing procedures. The video element of the module was used by a cohort of post-graduate students at the Technological University Dublin and the feedback was favourable. While acknowledging its advantages, the authors conclude that the cost, time and complexity of producing high-quality video should not be underestimated. Also, they note that keeping multimedia-rich courses current, particularly in an area of rapid technological change, is a challenge. E-learning course developers considering using video should carry-out both a pedagogical- and a cost-benefit analysis to establish if the inclusion of video is worthwhile. The most important component in producing an active learning experience continues to be the quality of the instructional design and content, not the media itself
Looks are situation-dependent properties
This thesis concerns the distinction between appearance and reality. Particularly, the metaphysical nature of a class of visual appearances that I call "looks." I answer the question of what looks are. My positions constitutes a break with philosophical tradition: looks are not minddependent properties, but objective--mind-independent--properties of objects. They are not, however, intrinsic properties, but relational properties objects have of projecting light of a certain informational character to a viewpoint. Looks-properties are instantiated relative to certain of the intrinsic properties of objects, spatial relations between objects and viewpoints, and environmental conditions on which the character of the light at the viewpoint depend.Dr. Matthew McGrath, Thesis Supervisor.Includes bibliographical references (pages 31-32)
Resonant Leptogenesis with nonholomorphic R-Parity violation and LHC Phenomenology
In R-parity violating supersymmetric models both leptogenesis and the correct
neutrino masses are hard to achieve together. The presence of certain soft
nonholomorphic R-parity violating terms helps to resolve this problem. We
consider a scenario where the lightest and the second-lightest neutralino are
nearly degenerate in mass and enough CP-asymmetry can be produced through
resonant leptogenesis. In this model, the lighter chargino and the lightest
neutralino are highly degenerate. We have relatively lighter gauginos which can
be produced at the LHC leading to heavily ionizing charged tracks. At the same
time this model can also generate the correct neutrino mass scale. Thus our
scenario is phenomenologically rich and testable at colliders.Comment: 17 pages, 7 figures, Numerical results are improved and new plots are
added, Journal version. arXiv admin note: text overlap with
arXiv:hep-ph/0006173 by other author
Quantum Control of Interacting Bosons in Periodic Optical Lattice
We study the avoided crossings in the dynamics of quantum controlled
excitations for an interacting two-boson system in an optical lattice.
Specifically, we perform numerical simulations of quantum control in this
system where driving pulses connect the undriven stationary states in a manner
characteristic of Stimulated Raman Adiabatic Passage (STIRAP). We demonstrate
that the dynamics of such a transition is affected by chaos induced avoided
crossings, resulting in a loss in coherence of the final outcome in the
adiabatic limit.Comment: Accepted for publication in Physica E. Typo corrections to final
versio
Risks to biodiversity and coastal livelihoods from artisanal elasmobranch fisheries in a Least Developed Country: The Gambia (West Africa)
Developing nations in tropical regions harbour rich biological resources on which humans depend for food, income and employment, yet data to aid their management is often lacking. In West Africa, the diversity and fisheries of elasmobranchs are poorly documented, despite them being known to be economically important and vulnerable to overexploitation. Rapid qualitative surveys of fish processing and landing sites in The Gambia from 2010-2018 revealed valuable new data on species composition, biology, relative abundance, fisheries and utilisation by humans. Diversity and abundance was dominated by batoids, with a major component comprising a large guitarfish (Glaucostegus cemiculus) that was apparently targeted, and a small whipray (Fontitrygon margaritella). Nearly all taxa recorded are classified by the IUCN Red List as Critically Endangered (angel sharks Squatina spp.), Endangered, Data Deficient, or Not Evaluated; several were endemic, of exceptional evolutionary distinctness, cryptic, possibly undescribed, and rare (including stingray Hypanus rudis not apparently recorded since description in 1870). Significant threats to biodiversity, coastal livelihoods and possibly food security are identified based on the apparent importance of elasmobranch fisheries and processing; the known inability of key taxa to withstand intensive fisheries; ‘fishing down the food web’ by intensive utilisation of F. margaritella; and the absence or rarity of previously common elasmobranch species that may be severely depleted in the region. This study provides data that may act as a starting point to aid sustainability accreditation of local fin-fisheries, and demonstrates the value of inexpensive and low-resolution data collection in developing countries
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