12,940 research outputs found
The Giant Branches of Open and Globular Clusters in the Infrared as Metallicity Indicators: A Comparison with Theory
We apply the giant branch slope-[Fe/H] relation derived by Kuchinski et al.
[AJ, 109, 1131 (1995)] to a sample of open clusters. We find that the slope of
the giant branch in K vs. (J-K) color-magnitude diagrams correlates with [Fe/H]
for open clusters as it does for metal-rich globular clusters but that the open
cluster data are systematically shifted to less negative values of giant branch
slope, at constant [Fe/H]. We use isochrone models to examine the theoretical
basis for this relationship and find that for a given value of [Fe/H], the
slope of the relationship remains constant with decreasing population age but
the relation shifts to less negative values of giant branch slope with
decreasing age. Both of these theoretical predictions agree with the trends
found in the data. Finally, we derive new coefficients for the giant branch
slope-[Fe/H] relation for specific members of 3 populations, metal-rich
globular clusters, bulge stars and open clusters.Comment: 16 pages including 3 figures (AASTEX), AJ Accepted, also available at
http://www.astronomy.ohio-state.edu/~martini/pubs.htm
Structural mapping from MSS-LANDSAT imagery: A proposed methodology for international geological correlation studies
A methodology is proposed for international geological correlation studies based on LANDSAT-MSS imagery, Bullard's model of continental fit and compatible structural trends between Northeast Brazil and the West African counterpart. Six extensive lineaments in the Brazilian study area are mapped and discussed according to their regional behavior and in relation to the adjacent continental margin. Among the first conclusions, correlations were found between the Sobral Pedro II Lineament and the megafaults that surround the West African craton; and the Pernambuco Lineament with the Ngaurandere Linemanet in Cameroon. Ongoing research to complete the methodological stages includes the mapping of the West African structural framework, reconstruction of the pre-drift puzzle, and an analysis of the counterpart correlations
Generation of polarization entangled photon pairs by a single crystal interferometric source pumped by femtosecond laser pulses
Photon pairs, highly entangled in polarization have been generated under
femtosecond laser pulse excitation by a type I crystal source, operating in a
single arm interferometric scheme. The relevant effects of temporal walk-off
existing in these conditions between the ordinary and extraordinary photons
were experimentally investigated. By introducing a suitable temporal
compensation between the two orthogonal polarization components highly
entangled pulsed states were obtained
Continuous variable cloning via network of parametric gates
We propose an experimental scheme for the cloning machine of continuous
quantum variables through a network of parametric amplifiers working as
input-output four-port gates.Comment: 4 pages, 2 figures. To appear on Phys. Rev. Let
Quantum tomography of the GHZ state
We present a method of generation of the Greenberger-Horne-Zeilinger state
involving type II and type I parametric downconversion, and triggering
photodetectors. The state generated by the proposed experimental set-up can be
reconstructed through multi-mode quantum homodyne tomography. The feasibility
of the measurement is studied on the basis of Monte-Carlo simulations.Comment: Paper submitted to the proceedings of the III Adriatico Research
Conference on Quantum Interferometry, ICTP, March 1-5,1999. 5 pages, 3 eps
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Project Gondwana: Jugaribe-SB-24
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