37,885 research outputs found
Polarization switching and induced birefringence in InGaAsP multiple quantum wells at 1.5 mu m
We analyze the 1.5mum wavelength operation of a room temperature polarization switch based on electron spin dynamics in InGaAsP multiple quantum wells. An unexpected difference in response for left and right circularly polarized pump light in pump-probe measurements was discovered and determined to be caused by an excess carrier induced birefringence. Transient polarization rotation and ellipticity were measured as a function of time delay. (C) 2002 American Institute of Physics.</p
The Galactic bulge as seen in optical surveys
The bulge is a region of the Galaxy of tremendous interest for understanding
galaxy formation. However measuring photometry and kinematics in it raises
several inherent issues, such as severe crowding and high extinction in the
visible. Using the Besancon Galaxy model and a 3D extinction map, we estimate
the stellar density as a function of longitude, latitude and apparent magnitude
and we deduce the possibility of reaching and measuring bulge stars with Gaia.
We also present an ongoing analysis of the bulge using the Canada-France-Hawaii
Telescope.Comment: In SF2A-2008: Proceedings of the Annual meeting of the French Society
of Astronomy and Astrophysic
Effects of Enamel Paint on the Behavior and Survival of the Periodical Cicada, \u3ci\u3eMagicicada Septendecim\u3c/i\u3e (Homoptera) and the Lesser Migratory Grasshopper, \u3ci\u3eMelanoplus Sanguinipes (Orthoptera).
We present information compiled from several studies on the effects of methods for marking individual arthropods on their longevity and behavior. Results from our own research on effects of enamel paint marking on two in- sect species, the periodical cicada, Magicicada septendecim, and the lesser migratory grasshopper, Melanoplus sanguinipes, are also presented. Neither species showed any adverse survivorship or behavioral effects from marking
Measurement of the Nodal Precession of WASP-33 b via Doppler Tomography
We have analyzed new and archival time series spectra taken six years apart
during transits of the hot Jupiter WASP-33 b, and spectroscopically resolved
the line profile perturbation caused by the Rossiter-McLaughlin effect. The
motion of this line profile perturbation is determined by the path of the
planet across the stellar disk, which we show to have changed between the two
epochs due to nodal precession of the planetary orbit. We measured rates of
change of the impact parameter and the sky-projected spin-orbit misalignment of
yr and
~ yr, respectively,
corresponding to a rate of nodal precession of
~ yr. This is only the
second measurement of nodal precession for a confirmed exoplanet transiting a
single star. Finally, we used the rate of precession to set limits on the
stellar gravitational quadrupole moment of
.Comment: Published in ApJL. 5 pages, 3 figures. Corrected error in the
calculation of J_
Warming temperatures and smaller body sizes : synchronous changes in growth of North Sea fishes
Funded by Marine Scotland SciencePeer reviewedPostprin
Whole body interaction
In this workshop we explore the notation of whole body interaction. We bring together different disciplines to create a new research direction for study of this emerging form of interaction
A perturbation density functional theory for the competition between inter and intramolecular association
Using the framework of Wertheim's thermodynamic perturbation theory we
develop the first density functional theory which accounts for intramolecular
association in chain molecules. To test the theory new Monte Carlo simulations
are performed at a fluid solid interface for a 4 segment chain which can both
intra and intermolecularly associate. The theory and simulation results are
found to be in excellent agreement. It is shown that the inclusion of
intramolecular association can have profound effects on interfacial properties
such as interfacial tension and the partition coefficient
The relaxation of OH (v = 1) and OD (v = 1) by H2O and D2O at temperatures from 251 to 390 K
We report rate coefficients for the relaxation of OH(v = 1) and OD(v = 1) by H2O and D2O as a function of temperature between 251 and 390 K. All four rate coefficients exhibit a negative dependence on temperature. In Arrhenius form, the rate coefficients for relaxation (in units of 10â12 cm3 moleculeâ1 sâ1) can be expressed as: for OH(v = 1) + H2O between 263 and 390 K: k = (2.4 ± 0.9) exp((460 ± 115)/T); for OH(v = 1) + D2O between 256 and 371 K: k = (0.49 ± 0.16) exp((610 ± 90)/T); for OD(v = 1) + H2O between 251 and 371 K: k = (0.92 ± 0.16) exp((485 ± 48)/T); for OD(v = 1) + D2O between 253 and 366 K: k = (2.57 ± 0.09) exp((342 ± 10)/T). Rate coefficients at (297 ± 1 K) are also reported for the relaxation of OH(v = 2) by D2O and the relaxation of OD(v = 2) by H2O and D2O. The results are discussed in terms of a mechanism involving the formation of hydrogen-bonded complexes in which intramolecular vibrational energy redistribution can occur at rates competitive with re-dissociation to the initial collision partners in their original vibrational states. New ab initio calculations on the H2OâHO system have been performed which, inter alia, yield vibrational frequencies for all four complexes: H2OâHO, D2OâHO, H2OâDO and D2OâDO. These data are then employed, adapting a formalism due to Troe (J. Troe, J. Chem. Phys., 1977, 66, 4758), in order to estimate the rates of intramolecular energy transfer from the OH (OD) vibration to other modes in the complexes in order to explain the measured relaxation ratesâassuming that relaxation proceeds via the hydrogen-bonded complexes
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