89 research outputs found
Perspectives on Astrophysics Based on Atomic, Molecular, and Optical (AMO) Techniques
About two generations ago, a large part of AMO science was dominated by
experimental high energy collision studies and perturbative theoretical
methods. Since then, AMO science has undergone a transition and is now
dominated by quantum, ultracold, and ultrafast studies. But in the process, the
field has passed over the complexity that lies between these two extremes. Most
of the Universe resides in this intermediate region. We put forward that the
next frontier for AMO science is to explore the AMO complexity that describes
most of the Cosmos.Comment: White paper submission to the Decadal Assessment and Outlook Report
on Atomic, Molecular, and Optical (AMO) Science (AMO 2020
Angular Momentum and the Formation of Stars and Black Holes
The formation of compact objects like stars and black holes is strongly
constrained by the requirement that nearly all of the initial angular momentum
of the diffuse material from which they form must be removed or redistributed
during the formation process. The mechanisms that may be involved and their
implications are discussed for (1) low-mass stars, most of which probably form
in binary or multiple systems; (2) massive stars, which typically form in
clusters; and (3) supermassive black holes that form in galactic nuclei. It is
suggested that in all cases, gravitational interactions with other stars or
mass concentrations in a forming system play an important role in
redistributing angular momentum and thereby enabling the formation of a compact
object. If this is true, the formation of stars and black holes must be a more
complex, dynamic, and chaotic process than in standard models. The
gravitational interactions that redistribute angular momentum tend to couple
the mass of a forming object to the mass of the system, and this may have
important implications for mass ratios in binaries, the upper stellar IMF in
clusters, and the masses of supermassive black holes in galaxies.Comment: Accepted by Reports on Progress in Physic
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Common polygenic variation in coeliac disease and confirmation of ZNF335 and NIFA as disease susceptibility loci
Coeliac disease (CD) is a chronic immune-mediated disease triggered by the ingestion of gluten. It has an estimated prevalence of approximately 1% in European populations. Specific HLA-DQA1 and HLA-DQB1 alleles are established coeliac susceptibility genes and are required for the presentation of gliadin to the immune system resulting in damage to the intestinal mucosa. In the largest association analysis of CD to date, 39 non-HLA risk loci were identified, 13 of which were new, in a sample of 12 014 individuals with CD and 12 228 controls using the Immunochip genotyping platform. Including the HLA, this brings the total number of known CD loci to 40. We have replicated this study in an independent Irish CD case–control population of 425 CD and 453 controls using the Immunochip platform. Using a binomial sign test, we show that the direction of the effects of previously described risk alleles were highly correlated with those reported in the Irish population, (P=2.2 × 10−16). Using the Polygene Risk Score (PRS) approach, we estimated that up to 35% of the genetic variance could be explained by loci present on the Immunochip (P=9 × 10−75). When this is limited to non-HLA loci, we explain a maximum of 4.5% of the genetic variance (P=3.6 × 10−18). Finally, we performed a meta-analysis of our data with the previous reports, identifying two further loci harbouring the ZNF335 and NIFA genes which now exceed genome-wide significance, taking the total number of CD susceptibility loci to 42
Perspectives on Astrophysics Based on Atomic, Molecular, and Optical (AMO) Techniques
About two generations ago, a large part of AMO science was dominated by experimental high energy collision studies and perturbative theoretical methods. Since then, AMO science has undergone a transition and is now dominated by quantum, ultracold, and ultrafast studies. But in the process, the field has passed over the complexity that lies between these two extremes. Most of the Universe resides in this intermediate region. We put forward that the next frontier for AMO science is to explore the AMO complexity that describes most of the Cosmos
Comparing Educational Programs to Improve Beef Production
This paper compares current Extension educational program efforts to improve the economic performance of the beef enterprise in Kentucky with the Sustainable Grazing System that has been developed and successfully applied to improve the performance of the beef industry in the High Rainfall Zone of Southern Australia. This comparison investigates problems addressed by each educational effort as well as different methods used by the programs to help producers improve the performance of the beef business. This comparison identifies potential difficulties faced by the Kentucky program that have been successfully addressed by the Sustainable Grazing Systems program in Southern Australia
- …