2,638 research outputs found
Scientific publications and presentations relating to planetary quarantine. Volume 5: The 1971 supplement
A bibliographic compilation, with approximately 200 listings, on planetary quarantine is presented. Also given are scientific publications, and presentations along with an author index
Momentum-Resolved Ultrafast Electron Dynamics in Superconducting Bi2Sr2CaCu2O8+delta
The non-equilibrium state of the high-Tc superconductor Bi2Sr2CaCu2O8+delta
and its ultrafast dynamics have been investigated by femtosecond time- and
angle-resolved photoemission spectroscopy well below the critical temperature.
We probe optically excited quasiparticles at different electron momenta along
the Fermi surface and detect metastable quasiparticles near the antinode. Their
decay through e-e scattering is blocked by a phase space restricted to the
nodal region. The lack of momentum dependence in the decay rates is in
agreement with relaxation dominated by Cooper pair recombination in a boson
bottleneck limit
Comet Shoemaker-Levy 9: An Active Comet
The important elements of the debate over the activity versus dormancy of comet Shoemaker Levy 9 (S-L 9) are reviewed. It is argued that the circularity of the isophotes in the inner comae of S-L 9 as well as the spatial dependencies of the comae brightness profiles are indicators of sustained dust production by S-L 9. It is also shown that the westward tail orientations, which were formerly interpreted as a sign of the comet's dormancy, are not a good indicator of either activity or dormancy. Rather, the tail orientations simply place constraints on the dust production rate for grains smaller than approx. equals 5(micron). All the available evidence points to S-L 9 as having been an active, dust-producing comet. Synthetic images of an active comet are fitted to Hubble Space Telescope images of the S-L 9 fragment K, and its grain size and outflow velocity distributions are extracted. These findings show that the appearance of the dust coma was dominated by large grains having radii between approx. equals 30 (micron) and approx. equals 3 mm, produced at a rate of M approx. equals 22 kg/ s, and ejected at outflow velocities of approx. equals 0.5 m/ s. Only upper limits on the production rates of smaller grains are obtained. The nucleus of fragment K was not observed directly but its size is restricted to lie within a rather narrow interval 0.4 less than or equal to Rf less than or equal to 1.2 km
Borealis sound an interactive wall for situational awareness: The impact of responsive architecture on users
This paper refers to the presence of visual communication elements in public spaces using interactive multimedia surfaces. The state of the art, the development of a proposal, and its evaluation are presented. The interactive surface applies to school of music “Escola de Música do Conservatório Nacional,” to which a design project was done in an academic context. The proposal aims to explore the incorporation of digital multimedia surfaces enhancing new dynamics while users walk in the interior of the building. Visual content will be displayed, and the interaction between users and the multimedia surfaces is done by the sounds produce by people and instruments. To assess the intuitive nature and relevance of the proposal, satisfaction and usability tests were conducted with the potential users. It was concluded that users appreciated the proposal and was able to perceive the effect people’s presence have in the interaction with the multimedia surface.info:eu-repo/semantics/acceptedVersio
Momentum dependent ultrafast electron dynamics in antiferromagnetic EuFe2As2
Employing the momentum-sensitivity of time- and angle-resolved photoemission
spectroscopy we demonstrate the analysis of ultrafast single- and many-particle
dynamics in antiferromagnetic EuFe2As2. Their separation is based on a
temperature-dependent difference of photo-excited hole and electron relaxation
times probing the single particle band and the spin density wave gap,
respectively. Reformation of the magnetic order occurs at 800 fs, which is four
times slower compared to electron-phonon equilibration due to a smaller
spin-dependent relaxation phase space
Integrated aircraft scheduling problem: An auto-adapting algorithm to find robust aircraft assignments for large flight plans
The overall airline scheduling process involves hierarchical steps starting with the network design and ending with crew assignment. Aircraft routing is especially important with respect to timing and costs for an airline. In this contribution, we focus on aircraft routing where aircraft are assigned to flight legs further considering maintenance requirements. We developed and implemented algorithms that extend the aircraft routing problem (ARP) by including profit and robustness. The latter objective is important as the dependencies of flights and airlines increases and deviations to the original time plan as unexpected events like volcano eruptions or heavy weather-related issues are difficult to handle. A robust aircraft routing ensures that unforeseen events have less impact. The results are compared to current state-of-the-art solutions. We developed a test instance-generator to create specific problems and build a library for future benchmarking tests
Synaptic localization and presynaptic function of calcium channel □4-subunits in cultured hippocampal neurons.
Crystal Symmetry Lowering in Chiral Multiferroic BaTaFeSiO observed by X-Ray Magnetic Scattering
Chiral multiferroic langasites have attracted attention due to their
doubly-chiral magnetic ground state within an enantiomorphic crystal. We report
on a detailed resonant soft X-ray diffraction study of the multiferroic
BaTaFeSiO at the Fe and oxygen edges. Below
() we observe the satellite reflections ,
, and where . The dependence of the scattering intensity on X-ray polarization and
azimuthal angle indicate that the odd harmonics are dominated by the
out-of-plane (-axis) magnetic dipole while the
originates from the electron density distortions accompanying magnetic order.
We observe dissimilar energy dependences of the diffraction intensity of the
purely magnetic odd-harmonic satellites at the Fe edge. Utilizing
first-principles calculations, we show that this is a consequence of the loss
of threefold crystal symmetry in the multiferroic phase
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