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Sedimentary rocks in Bequerel crater: origin as polar layered deposits during high obliquity
Abstract not available
Possible mechanism for achieving glass-like thermal conductivities in crystals with off-center atoms
In the filled Ga/Ge clathrate, Eu and Sr are off-center in site 2 but Ba is
on-center. All three filler atoms (Ba,Eu,Sr) have low temperature Einstein
modes; yet only for the Eu and Sr systems is there a large dip in the thermal
conductivity, attributed to the Einstein modes. No dip is observed for Ba. Here
we argue that it is the off-center displacement that is crucial for
understanding this unexplained difference in behavior. It enhances the coupling
between the "rattler" motion and the lattice phonons for the Eu and Sr systems,
and turns on/off another scattering mechanism (for 1K < T < 20K) produced by
the presence/absence of off-center sites. The random occupation of different
off-center sites produces a high density of symmetry-breaking defects which
scatters phonons. It may also be important for improving our understanding of
other glassy systems.Comment: 4 pages, 1 figure (2 parts) -- v2: intro broadened; strengthened
arguments regarding need for additional phonon scattering mechanis
The Modulation of Multiple Phases Leading to the Modified KdV Equation
This paper seeks to derive the modified KdV (mKdV) equation using a novel
approach from systems generated from abstract Lagrangians that possess a
two-parameter symmetry group. The method to do uses a modified modulation
approach, which results in the mKdV emerging with coefficients related to the
conservation laws possessed by the original Lagrangian system. Alongside this,
an adaptation of the method of Kuramoto is developed, providing a simpler
mechanism to determine the coefficients of the nonlinear term. The theory is
illustrated using two examples of physical interest, one in stratified
hydrodynamics and another using a coupled Nonlinear Schr\"odinger model, to
illustrate how the criterion for the mKdV equation to emerge may be assessed
and its coefficients generated.Comment: 35 pages, 5 figure
ACS photometry of extended, luminous globular clusters in the outskirts of M31
A new population of extended, luminous globular clusters has recently been
discovered in the outskirts of M31. These objects have luminosities typical of
classical globular clusters, but much larger half-light radii. We report the
first results from deep ACS imaging of four such clusters, one of which is a
newly-discovered example lying at a projected distance of ~60 kpc from M31. Our
F606W, F814W colour-magnitude diagrams extend ~3 magnitudes below the
horizontal branch level, and clearly demonstrate, for the first time, that all
four clusters are composed of >10 Gyr old, metal-poor stellar populations. No
evidence for multiple populations is observed. From a comparison with Galactic
globular cluster fiducials we estimate metallicities in the range -2.2 < [Fe/H]
< -1.8. The observed horizontal branch morphologies show a clear second
parameter effect between the clusters. Preliminary radial luminosity profiles
suggest integrated magnitudes in the range -6.6 < M_V < -7.7, near the median
value of the globular cluster luminosity function. Our results confirm that
these four objects are bona fide old, metal-poor globular clusters, albeit with
combined structures and luminosities unlike those observed for any other
globular clusters in the Local Group or beyond.Comment: 12 pages, 3 figures, 1 table; accepted for publication in ApJ Letter
Alignments of the Dominant Galaxies in Poor Clusters
We have examined the orientations of brightest cluster galaxies (BCGs) in
poor MKW and AWM clusters and find that, like their counterparts in richer
Abell clusters, poor cluster BCGs exhibit a strong propensity to be aligned
with the principal axes of their host clusters as well as the surrounding
distribution of nearby (< 20/h Mpc) Abell clusters. The processes responsible
for dominant galaxy alignments are therefore independent of cluster richness.
We argue that these alignments most likely arise from anisotropic infall of
material into clusters along large-scale filaments.Comment: 8 pages, 5 figure
The impact of two-dimensional elastic disk
The impact of a two-dimensional elastic disk with a wall is numerically
studied. It is clarified that the coefficient of restitution (COR) decreases
with the impact velocity. The result is not consistent with the recent
quasi-static theory of inelastic collisions even for very slow impact. The
abrupt drop of COR is found due to the plastic deformation of the disk, which
is assisted by the initial internal motion.(to be published in J. Phys. Soc.
Jpn.)Comment: 6 Pages,2 figure
Nutritional Management Post-AI to Enhance Pregnancy Outcomes
Effective replacement heifer development is a critical segment of the integrated management program in an efficient beef cow production system. The most critical factor determining the success of any heifer development program is nutrition. Most efforts are concentrated in providing the right amount and quality of feed to achieve gains from 1.5 to 2.0 lb/day, so heifers can reach 65% of their mature BW by the day of breeding. Approximately 80% of the U.S. cow-herds are spring calving, which means that producers utilizing estrous synchronization and AI are keeping their heifers in a feedlot environment until heifers are inseminated. Immediately following AI, heifers are typically moved to pasture. It is known that maternal recognition of pregnancy takes place around d 15 - 17 post-insemination and that transporting animals near this time compromises conception rates. However, moving heifers within the first 5 days post-insemination does not cause this reduction. Although, research suggests that conception rates are compromised when heifers are placed on early growth pasture forages. We hypothesized that feeding this high moisture pasture forage at turnout is limiting DMI which in turn causes a temporary energy deficiency that results in temporary heifer weight loss during the critical stages of early embryonic development and maternal recognition of pregnancy. Therefore, it is beneficial to ensure heifers maintain the same plane of nutrition after breeding, at least until day 25 when the embryo should be completely attached to the uterus. If this is true, maintaining a positive plane of nutrition on heifers after breeding will increase 1st service conception rates, improving herd fertility and longevity
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