5,500 research outputs found
Effect of realistic interatomic interactions and two-body correlation on the heat capacity of a trapped BEC
An approximate many-body theory has been used to calculate the heat capacity
and the condensate fraction of a BEC with effective repulsive interaction. The
effect of interactions has been analyzed and compared with the non-interacting
case. It has been found that the repulsive interaction lowers the critical
temperature from the value found in the non-interacting case. The difference
between the critical temperatures increases with the increase in the total
number of atoms in the trap.Comment: 15 pages, 5 figure
Electrochemical Oxidation of Methanol, Formic Acid & Hydrazine at Pt-Ni, Pt-Au & Pt-Pd Electrodes
315-31
Biferroic YCrO3
YCrO3 which has a monoclinic structure, shows weak ferromagnetism below 140 K
(TN) and a ferroelectric transition at 473 K accompanied by hysteresis. We have
determined the structure and energetics of YCrO3 with ferromagnetic and
antiferromagnetic ordering by means of first-principles density functional
theory calculations, based on pseudopotentials and a plane wave basis. The
non-centrosymmetric monoclinic structure is found to be lower in energy than
the orthorhombic structure, supporting the biferroic nature of YCrO3.Comment: 16 pages including figure
Influence of gas flow rate on liquid distribution in trickle-beds using perforated plates as liquid distributors
Two wire mesh tomography devices and a liquid collector were used to study
the influence of the gas flow rate on liquid distribution when fluids
distribution on top of the reactor is ensured by a perforated plate. In
opposition to most of the studies realized by other authors, conditions in
which the gas has a negative impact in liquid distribution were evidenced.
Indeed, the obtained results show that the influence of gas flow rate depends
on the quality of the initial distribution, as the gas forces the liquid to
"respect" the distribution imposed at the top of the reactor. Finally, a
comparison between the two measuring techniques shows the limitations of the
liquid collector and the improper conclusions to which its use could lead
Hot Populations in M87 Globular Clusters
We have obtained HST/STIS far- and near-UV photometry of globular clusters in
four fields in the gE galaxy M87. To a limit of m(FUV) = 25 we detect a total
of 66 globular clusters (GCs) in common with the deep HST optical-band study of
Kundu et al. (1999). Despite strong overlap in V- and I-band properties, the
M87 GCs have UV/optical properties that are distinct from clusters in the Milky
Way and in M31. M87 clusters, especially metal-poor ones, produce larger hot HB
populations than do Milky Way analogues. Cluster mass is probably not a factor
in these distinctions. The most metal-rich M87 GCs in our sample are near Z_sun
and overlap the local E galaxy sample in estimated Mg_2 line indices.
Nonetheless, the clusters produce much more UV light at a given Mg_2, being up
to 1 mag bluer than any gE galaxy in (FUV-V) color. The M87 GCs do not appear
to represent a transition between Milky Way-type clusters and E galaxies. The
differences are in the correct sense if the clusters are significantly older
than the E galaxies. Comparisons with Galactic open clusters indicate that the
hot stars lie on the extreme horizontal branch, rather than being blue
stragglers, and that the EHB becomes well populated for ages > 5 Gyr. We find
that 43 of our UV detections have no optical-band counterparts. Most appear to
be UV-bright background galaxies, seen through M87. Eleven NUV variable sources
detected at only one epoch in the central field are probably classical novae.
[Abridged]Comment: 70 pages, 25 figures (including 4 jpgs), 7 tables. To appear in AJ.
Full resolution version available at
http://www.astro.virginia.edu/~rwo/m87/m87-hotpops.pd
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