795 research outputs found
Mating Ewes on Condensed Tannin-Containing Forages Increases Ewe Reproductive Rate and Reduces Lamb Mortality
Action of condensed tannin (CT) reduces forage protein degradation in the rumen and increases the absorption of amino acids from the small intestine (Barry & McNabb 1999). This paper reports the effects of grazing ewes on two CT-containing forages during mating upon ewe reproductive rate and lamb mortality
High resolution infrared spectra of NGC 6342 and NGC 6528: two moderately reddened Bulge Globular Clusters
Using the NIRSPEC spectrograph at Keck II, we have obtained infrared echelle
spectra covering the range 1.5-1.8 micron for the moderately reddened bulge
globular clusters NGC 6342 and NGC 6528, finding [Fe/H]= -0.60 and -0.17 dex,
respectively. We measure an average alpha-enhancement of approx +0.33 dex in
both clusters, consistent with previous measurements on other metal rich bulge
clusters, and favoring the scenario of a rapid bulge formation and chemical
enrichment. We also measure very low 12C/13C isotopic ratios (approx 5 in NGC
6342 and approx 8 in NGC 6528), suggesting that extra-mixing mechanisms due to
cool bottom processing are at work during evolution along the Red Giant Branch.Comment: 8 pages, 5 figures, accepted by MNRA
The origin of the split red clump in the Galactic bulge of the Milky Way
Near the minor axis of the Galactic bulge, at latitudes b < -5 degrees, the
red giant clump stars are split into two components along the line of sight. We
investigate this split using the three fields from the ARGOS survey that lie on
the minor axis at (l,b) = (0,-5), (0,-7.5), (0,-10) degrees. The separation is
evident for stars with [Fe/H] > -0.5 in the two higher-latitude fields, but not
in the field at b = -5 degrees. Stars with [Fe/H] < -0.5 do not show the split.
We compare the spatial distribution and kinematics of the clump stars with
predictions from an evolutionary N-body model of a bulge that grew from a disk
via bar-related instabilities. The density distribution of the peanut-shaped
model is depressed near its minor axis. This produces a bimodal distribution of
stars along the line of sight through the bulge near its minor axis, very much
as seen in our observations. The observed and modelled kinematics of the two
groups of stars are also similar. We conclude that the split red clump of the
bulge is probably a generic feature of boxy/peanut bulges that grew from disks,
and that the disk from which the bulge grew had relatively few stars with
[Fe/H] < -0.5Comment: 12 pages, 9 figures, accepted for publication in Ap
Abundances of Baade's Window Giants from Keck/HIRES Spectra: I. Stellar Parameters and [Fe/H] Values
We present the first results of a new abundance survey of the Milky Way bulge
based on Keck/HIRES spectra of 27 K-giants in the Baade's Window (, ) field. The spectral data used in this study are of much higher resolution
and signal-to-noise than previous optical studies of Galactic bulge stars. The
[Fe/H] values of our stars, which range between -1.29 and , were used to
recalibrate large low resolution surveys of bulge stars. Our best value for the
mean [Fe/H] of the bulge is . This mean value is similar to the
mean metallicity of the local disk and indicates that there cannot be a strong
metallicity gradient inside the solar circle. The metallicity distribution of
stars confirms that the bulge does not suffer from the so-called ``G-dwarf''
problem. This paper also details the new abundance techniques necessary to
analyze very metal-rich K-giants, including a new Fe line list and regions of
low blanketing for continuum identification.Comment: Accepted for publication in January 2006 Astrophysical Journal. Long
tables 3--6 withheld to save space (electronic tables in journal paper). 53
pages, 10 figures, 9 table
s- and r-process element abundances in the CMD of 47 Tucanae using the Robert Stobie Spectrograph on SALT
A recent study by Wylie et al 2006 has revealed that s-process element
abundances are enhanced relative to iron in both red giant branch and
asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into
s-process element abundances throughout the colour-magnitude diagram of 47
Tucanae is vital in order to determine whether the observed enhancements are
intrinsic to the cluster. This paper explores this possibility through
observational and theoretical means. The visibility of s- and r-process element
lines in synthetic spectra of giant and dwarf stars throughout the colour
magnitude diagram of 47 Tucanae has been explored. It was determined that a
resolving power of 10 000 was sufficient to observe s-process element abundance
variations in globular cluster giant branch stars. These synthetic results were
compared with the spectra of eleven 47 Tucanae giant branch stars observed
during the performance verification of the Robert Stobie Spectrograph on the
Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one
r-process element, Eu, were investigated. No abundance variations were found
such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power,
R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the
s-process element abundances could be determined.Comment: 7 pages, 11 figure
A low-absorption disk zone at low Galactic latitude in Centaurus
We investigate the properties of two stellar concentrations in a
low-absorption disk zone in Centaurus, located respectively at
, , and , . The present analysis is based mostly on 2MASS photometry, as well as
optical photometry. Based on colour-magnitude diagrams and stellar radial
density profiles, we show that these concentrations are not open star clusters.
Instead, they appear to be field stars seen through a differentially-reddened
window. We estimate that the bulk of the stars in both stellar concentrations
is located at kpc from the Sun, a distance consistent with that of
the Sgr-Car arm in that direction. This low-absorption window allows one to
probe into distant parts of the disk besides the Sgr-Car arm, probably the
tangent part of the Sct-Cru arm, and/or the far side of the Sgr-Car arm in that
direction. The main sequence associated to the Sgr-Car arm is reddened by
\ebv\sim0.5, so that this window through the disk is comparable in reddening
to Baade's window to the bulge. We also investigate the nature of the open
cluster candidate Ru 166. The presently available data do not allow us to
conclude whether Ru 166 is an actual open cluster or field stars seen through a
small-scale low-absorption window
High resolution near-IR spectra of NGC 6624 and NGC 6569
We present the first abundances analysis based on high-resolution infrared
(IR) echelle spectra of NGC 6569 and NGC 6624, two moderately reddened globular
clusters located in the outer bulge of the Galaxy. We find
[Fe/H]=-0.790.02 dex and [Fe/H]=-0.690.02 dex for NGC 6569 and NGC
6624, respectively and an average -elements enhancement of
+0.430.02 dex and +0.390.02 dex, consistent with previous
measurements on other metal-rich Bulge clusters. We measure accurate radial
velocities of and
and velocity dispersions of and for NGC 6569 and NGC 6624, respectively. Finally, we find very low
isotopics ratio (7 in NGC 6624 and 5 in NGC
6569), confirming the presence extra-mixing mechanisms during the red giant
branch evolution phase.Comment: 7 pages, 3 figures, accepted for publication on MNRA
The FERRUM project: laboratory-measured transition probabilities for Cr II
Aims: We measure transition probabilities for Cr II transitions from the z
^4H_J, z ^2D_J, y ^4F_J, and y ^4G_J levels in the energy range 63000 to 68000
cm^{-1}. Methods: Radiative lifetimes were measured using time-resolved
laser-induced fluorescence from a laser-produced plasma. In addition, branching
fractions were determined from intensity-calibrated spectra recorded with a UV
Fourier transform spectrometer. The branching fractions and radiative lifetimes
were combined to yield accurate transition probabilities and oscillator
strengths. Results: We present laboratory measured transition probabilities for
145 Cr II lines and radiative lifetimes for 14 Cr II levels. The
laboratory-measured transition probabilities are compared to the values from
semi-empirical calculations and laboratory measurements in the literature.Comment: 13 pages. Accepted for publication in A&
Clustering Attitudes and Behaviors of High/Low Involvement Grocery Shopper
The purpose of this exploratory and quantitative study was to examine the attitudes and behaviors of 14,807 grocery shop- pers. These respondents across the US were asked to answer attitudinal, behavioral, and demographic related questions. Shoppers were profiled by analyzing their responses to 16 relevant attitudinal and behavioral questions. A cluster analysis was performed followed by a discriminant analysis to deter- mine attitudinal and behavioral variables explaining cluster membership. A cross-tabulation analysis assessed demo- graphic variables that correlated with cluster membership. Two clusters were identified: high and low involvement grocery shoppers. In an event that has long been perceived as low involvement, a large percentage (53%) can be categorized as high involvement grocery shoppers. These shoppers tend to be younger. They were more likely to enjoy the hunt of finding products/deals, seek the advice of others and perceive that the products they buy reflect upon them. Grocery stores have a significant opportunity to target this high involvement shop- per. Grocery stores will need to create an integrative, engaging online and in-store experience to attract high involvement shoppers and ultimately increase store loyalty. The results of this research has significant communication, branding and digital marketing implications
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