8,428 research outputs found
The Southern Vilnius Photometric System. IV. The E Regions Standard Stars
This paper is the fourth in a series on the extension of the Vilnius
photometric system to the southern hemisphere. Observations were made of 60
stars in the Harvard Standard E regions to increase a set of standard stars.Comment: 6 pages, TeX, requires 2 macros (baltic2.tex, baltic4.tex) included
no figures, to be published in Baltic Astronomy, Vol 6, pp1-6 (1997
Bulge Globular Clusters in Spiral Galaxies
There is now strong evidence that the metal-rich globular clusters (GC) near
the center of our Galaxy are associated with the Galactic bulge rather than the
disk as previously thought. Here we extend the concept of bulge GCs to the GC
systems of nearby spiral galaxies. In particular, the kinematic and metallicity
properties of the GC systems favor a bulge rather than a disk origin. The
number of metal-rich GCs normalized by the bulge luminosity is roughly constant
(i.e. bulge S_N ~ 1) in nearby spirals, and this value is similar to that for
field ellipticals when only the red (metal--rich) GCs are considered. We argue
that the metallicity distributions of GCs in spiral and elliptical galaxies are
remarkably similar, and that they obey the same correlation of mean GC
metallicity with host galaxy mass. We further suggest that the metal-rich GCs
in spirals are the direct analogs of the red GCs seen in ellipticals. The
formation of a bulge/spheroidal stellar system is accompanied by the formation
of metal-rich GCs. The similarities between GC systems in spiral and elliptical
galaxies appear to be greater than the differences.Comment: 5 pages, Latex, 2 figures, 1 table, Accepted for publication in ApJ
Letter
Quantum diffusion on a cyclic one dimensional lattice
The quantum diffusion of a particle in an initially localized state on a
cyclic lattice with N sites is studied. Diffusion and reconstruction time are
calculated. Strong differences are found for even or odd number of sites and
the limit N->infinit is studied. The predictions of the model could be tested
with micro - and nanotechnology devices.Comment: 17 pages, 5 figure
Exercise interventions for preventing dementia or delaying cognitive decline in people with mild cognitive impairment
This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the effects of exercise interventions for preventing dementia in people with mild cognitive impairment. We refer to Forbes 2015b and Forbes 2015c for the review protocols on exercise interventions for maintaining cognitive function in cognitively healthy people in mid and late life
Exercise interventions for maintaining cognitive function in cognitively healthy people in mid life
This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the effects ofexercise interventions on cognitive function in cognitively healthy people in mid life. We refer to Forbes 2015b for the review protocol on Exercise interventions for maintaining cognitive function in cognitively healthy people in late life and to Forbes 2015c for the review protocol on Exercise interventions for prevention of dementia in people with mild cognitive impairment
Extended X-Ray Emission from QSOs
We report Chandra ACIS observations of the fields of 4 QSOs showing strong
extended optical emission-line regions. Two of these show no evidence for
significant extended X-ray emission. The remaining two fields, those of 3C
249.1 and 4C 37.43, show discrete (but resolved) X-ray sources at distances
ranging from ~10 to ~40 kpc from the nucleus. In addition, 4C 37.43 also may
show a region of diffuse X-ray emission extending out to ~65 kpc and centered
on the QSO. It has been suggested that extended emission-line regions such as
these may originate in the cooling of a hot intragroup medium. We do not detect
a general extended medium in any of our fields, and the upper limits we can
place on its presence indicate cooling times of at least a few 10^9 years. The
discrete X-ray emission sources we detect cannot be explained as the X-ray jets
frequently seen associated with radio-loud quasars, nor can they be due to
electron scattering of nuclear emission. The most plausible explanation is that
they result from high-speed shocks from galactic superwinds resulting either
from a starburst in the QSO host galaxy or from the activation of the QSO
itself. Evidence from densities and velocities found from studies of the
extended optical emission around QSOs also supports this interpretation.Comment: Accepted by ApJ. 9 pages including 5 figure
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