23,804 research outputs found
Visible Airglow Experiment data analysis
The Visible Airglow Experiment (VAE) was designed to provide detailed profiles of the distribution of excited states of atoms and molecules in the upper atmosphere. The studies supported during the funding period (1983 - 1989) have made significant contributions in the area of thermospheric aeronomy, and the progress during the first four years of this period has been reviewed by Hays et al. (1988). The investigations carried out have resulted in more than 20 publications, and these are summarized
(Non)Thermal Aspects of Charmonium Production and a New Look at J/ Suppression
To investigate a recent proposal that J/ production in
ultra-relativistic nuclear collisions is of thermal origin we have reanalyzed
the data from the NA38/50 collaboration within a thermal model including charm.
Comparison of the calculated with measured yields demonstrates the non-thermal
origin of hidden charm production at SPS energy. However, the ratio
/(J/ exhibits, in central nucleus-nucleus collisions, thermal
features which lead us to a new interpretation of open charm and charmonium
production at SPS energy. Implications for RHIC and LHC energy measurements
will be discussed.Comment: 12 pages, 3 eps figures, final version with slight corrections, Phys.
Lett. B (in print
Battery simulation program
Computer program calculates spacecraft battery energy at specific times dictated by input sequence of recharge, discharge, and no activity phases. Recharge phases are assumed during times not specified, unless batteries are fully charged. Warnings are printed when energy falls below specified level. Program assumes two identical batteries
Even Orientations and Pfaffian graphs
We give a characterization of Pfaffian graphs in terms of even orientations,
extending the characterization of near bipartite non--pfaffian graphs by
Fischer and Little \cite{FL}. Our graph theoretical characterization is
equivalent to the one proved by Little in \cite{L73} (cf. \cite{LR}) using
linear algebra arguments
Even Orientations of Graphs: Part I
A graph G is 1-extendable if every edge belongs to at least one 1-factor. Let
G be a graph with a 1-factor F. Then an even F-orientation of G is an
orientation in which each F-alternating cycle has exactly an even number of
edges directed in the same fixed direction around the cycle.
In this paper, we examine the structure of 1-extendible graphs G which have
no even F-orientation where F is a fixed 1-factor of G. In the case of cubic
graphs we give a characterization. In a companion paper [M. Abreu, D. Labbate
and J. Sheehan. Even orientations of graphs: Part II], we complete this
characterization in the case of regular graphs, graphs of connectivity at least
four and k--regular graphs for . Moreover, we will point out a
relationship between our results on even orientations and Pfaffian graphs
developed in [M. Abreu, D. Labbate and J. Sheehan. Even orientations and
Pfaffian graphs].Comment: 40 pages, 2 figure
On the lack of stellar bars in Coma dwarf galaxies
We present a study of the bar fraction in the Coma cluster galaxies based on
a sample of ~190 galaxies selected from the SDSS-DR6 and observed with the
Hubble Space Telescope (HST) Advanced Camera for Survey (ACS). The
unprecedented resolution of the HST-ACS images allows us to explore the
presence of bars, detected by visual classification, throughout a luminosity
range of 9 mag (-23 < M_r < -14), permitting us to study the poor known region
of dwarf galaxies. We find that bars are hosted by galaxies in a tight range of
both luminosities (-22 < M_r < -17) and masses (10^9 < M*/Msun < 10^11). In
addition, we find that the bar fraction does not vary significantly when going
from the center to the cluster outskirts, implying that cluster environment
plays a second-order role in bar formation/evolution. The shape of the bar
fraction distribution with respect to both luminosity and mass is well matched
by the luminosity distribution of disk galaxies in Coma, indicating that bars
are good tracers of cold stellar disks.Comment: 2 pages, 1 figure, to appear in the proceedings of the conference "A
Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010
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