4,390 research outputs found
Transformation Optics, Generalized Cloaking and Superlenses
In this paper, transformation optics is presented together with a
generalization of invisibility cloaking: instead of an empty region of space,
an inhomogeneous structure is transformed via Pendry's map in order to give, to
any object hidden in the central hole of the cloak, a completely arbitrary
appearance. Other illusion devices based on superlenses considered from the
point of view of transformation optics are also discussed.Comment: 7 pages (two columns), 9 figures, to appear in IEEE Trans. Mag.,
invited paper in Compumag 2009 (Florianopolis, Brasil), corresponding slides
available on http://www.fresnel.fr/perso/nicolet
SCD: A 3 States Startle Copying Display to Manage Deleterious Effects of Extreme Emergency Situation.
The management of cognitive resources are central in the case of a decision-making process by pilots. We undertake a study involving Airbus 400M pilots and allowing to understand these mechanisms and to propose recommendations for the design of a tool to assist in the management of their cognitive resources. We find that in the most critical cases and under strong temporal pressure, the maintenance of control of the situation corresponds to a survival type behavior which alone can allow a return to the metarules (back to basics). Our display management proposal allows the pilot to maintain control of the situation regardless of his capabilities. It allows a phase of stabilization by a reduction of the stress, then a phase of soft recovery of the control and the management of the mission on larger spatiotemporal dimensions. Three modes of entry in the HMI are envisaged: spontaneous, proposed and on demand
Anharmonicity and asymmetry of Landau levels for a two-dimensional electron gas
We calculate the density of states of a two dimensional electron gas located
at the interface of a GaAlAs/GaAs heterojunction. The disorder potential which
is generally created by a single doping layer behind a spacer, is here enhanced
by the presence of a second delta doped layer of scatterers which can be
repulsive or attractive impurities. We have calculated the density of states by
means of the Klauder's approximation, in the presence of a magnetic field of
arbitrary strength. At low field either band tails or impurity bands are
observed for attractive potentials, depending on the impurity concentration. At
higher field, impurity bands are observed for both repulsive and attractive
potentials. We discuss the effect of such an asymmetrical density of states on
the transport properties in the quantum Hall effect regime.Comment: 22 pages, 12 figures. submitted to Phys. Rev.
First attempt to motion corrected flow encoding using free-breathing phase-contrast CINE MRI
International audienceThis study demonstrates the feasibility of free-breathing phase-contrast CINE MRI without averaging. A new version of the CINE GRICS algorithm[1] was used to correct for motion
Size-dependent optical properties of colloidal PbS quantum dots
We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots) by combining-the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. At high energies, the molar extinction coefficient epsilon increases With the Not volume d(3) and agrees with theoretical calculations using the Maxwell-Garnett effective medium theory and bulk values for the Qdot dielectric function. This demonstrates that quantum confinement has no influence on E in this spectral range, and it provides an accurate method to calculate the Qdot concentration. Around the band gap, epsilon only increases with d(1.3), and values are comparable to the epsilon of PbSe Qdots. The data are related to the oscillator strength f(if) of the band gap transition and results agree well with theoretical tight-binding calculations, predicting a linear dependence of f(if) on d. For both PbS and PbSe Qdots, the exciton lifetime tau is calculated from f(if). We find values ranging between 1 and 3 mu s, in agreement with experimental literature data from time-resolved luminescence spectroscopy. Our results provide a thorough general framework to calculate and understand the optical properties of suspended colloidal quantum dots. Most importantly, it highlights the significance of the local field factor in these systems
The Certification of the Mass Concentrations of Aluminium, Selenium and Zinc in Human Serum, BCR-637, BCR-638, BCR-639.
Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel
Dynamic Co-movements between Economic Policy Uncertainty and Housing Market Returns
We examine dynamic correlations between housing market returns and economic policy uncertainty in the United States. Our findings suggest that correlations are time-varying and sensitive to economic fundamentals and US recessions
The Certification of the Mass Concentrations of Lead and Cadmium in Reconstituted Human Blood. BCR-634, BCR-635, BCR-636.
Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel
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