204 research outputs found
Genome-Wide Association Studies of Grain Yield Components in Diverse Sorghum Germplasm
Citation: Boyles, R. E., Cooper, E. A., Myers, M. T., Brenton, Z., Rauh, B. L., Morris, G. P., & Kresovich, S. (2016). Genome-Wide Association Studies of Grain Yield Components in Diverse Sorghum Germplasm. Plant Genome, 9(2), 17. doi:10.3835/plantgenome2015.09.0091Grain yield and its primary determinants, grain number and weight, are important traits in cereal crops that have been well studied; however, the genetic basis of and interactions between these traits remain poorly understood. Characterization of grain yield per primary panicle (YPP), grain number per primary panicle (GNP), and 1000-grain weight (TGW) in sorghum [Sorghum bicolor (L.) Moench], a hardy C-4 cereal with a genome size of similar to 730 Mb, was implemented in a diversity panel containing 390 accessions. These accessions were genotyped to obtain 268,830 single-nucleotide polymorphisms (SNPs). Genome-wide association studies (GWAS) were performed to identify loci associated with each grain yield component and understand the genetic interactions between these traits. Genome-wide association studies identified associations across the genome with YPP, GNP, and TGW that were located within previously mapped sorghum QTL for panicle weight, grain yield, and seed size, respectively. There were no significant associations between GNP and TGW that were within 100 kb, much greater than the average linkage disequilibrium (LD) in sorghum. The identification of nonoverlapping loci for grain number and weight suggests these traits may be manipulated independently to increase the grain yield of sorghum. Following GWAS, genomic regions surrounding each associated SNP were mined for candidate genes. Previously published expression data indicated several TGW candidate genes, including an ethylene receptor homolog, were primarily expressed within developing seed tissues to support GWAS. Furthermore, maize (Zea mays L.) homologs of identified TGW candidates were differentially expressed within the seed between small- and large-kernel lines from a segregating maize population
The Fueling and Evolution of AGN: Internal and External Triggers
In this chapter, I review the fueling and evolution of active galactic nuclei
(AGN) under the influence of internal and external triggers, namely intrinsic
properties of host galaxies (morphological or Hubble type, color, presence of
bars and other non-axisymmetric features, etc) and external factors such as
environment and interactions. The most daunting challenge in fueling AGN is
arguably the angular momentum problem as even matter located at a radius of a
few hundred pc must lose more than 99.99 % of its specific angular momentum
before it is fit for consumption by a BH. I review mass accretion rates,
angular momentum requirements, the effectiveness of different fueling
mechanisms, and the growth and mass density of black BHs at different epochs. I
discuss connections between the nuclear and larger-scale properties of AGN,
both locally and at intermediate redshifts, outlining some recent results from
the GEMS and GOODS HST surveys.Comment: Invited Review Chapter to appear in LNP Volume on "AGN Physics on All
Scales", Chapter 6, in press. 40 pages, 12 figures. Typo in Eq 5 correcte
Establishment and dynamics of the balsam fir seedling bank in old forests of northeastern Quebec
This study examines balsam fir (Abies balsamea (L.) Mill.) recruitment in old fir stands. Studying the regeneration of these stands is essential to understand the regeneration dynamic of the species in the absence of standdestroying disturbances. The objectives were (1) to obtain substrate-seedling associations for different age-classes and according to the presence or absence of adventitious roots; (2) to evaluate the contribution of the seed rain to seedling recruitment; (3) to re-examine age structures using the most appropriate method that minimizes estimation errors due to the presence of adventitious roots. A total of 90 quadrats (1 m2) were established along transects. In each quadrat, subtrates were characterized (type and topography) and their area was estimated. All balsam fir seedlings (<50 cm tall) present in the quadrats were located, harvested whole (root and shoot), and described (age, height, presence of adventitious roots, etc). Fir seedlings were strongly associated with woody mounds covered with thin mats of mixed mosses and Pleurozium shreberi (Bird.) Mitt. but negatively associated with flat topography particularly dominated by Hylocomium splendens (Hedw.) B.S.G. The presence of adventitious root is related to seedling age more than substrate type or topography. The age structure is in agreement with seed production and disturbance regime
Observation of exclusive DVCS in polarized electron beam asymmetry measurements
We report the first results of the beam spin asymmetry measured in the
reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry
with a sin(phi) modulation is observed, as predicted for the interference term
of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The
amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and
leading-twist pQCD, the alpha is directly proportional to the imaginary part of
the DVCS amplitude.Comment: 6 pages, 5 figure
A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments
We measured the inclusive electron-proton cross section in the nucleon
resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2
with the CLAS detector. The large acceptance of CLAS allowed for the first time
the measurement of the cross section in a large, contiguous two-dimensional
range of Q**2 and x, making it possible to perform an integration of the data
at fixed Q**2 over the whole significant x-interval. From these data we
extracted the structure function F2 and, by including other world data, we
studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate
higher twist contributions. The small statistical and systematic uncertainties
of the CLAS data allow a precise extraction of the higher twists and demand
significant improvements in theoretical predictions for a meaningful comparison
with new experimental results.Comment: revtex4 18 pp., 12 figure
Search for the Decay
We have searched for the decay of the tau lepton into seven charged particles
and zero or one pi0. The data used in the search were collected with the CLEO
II detector at the Cornell Electron Storage Ring (CESR) and correspond to an
integrated luminosity of 4.61 fb^(-1). No evidence for a signal is found.
Assuming all the charged particles are pions, we set an upper limit on the
branching fraction, B(tau- -> 4pi- 3pi+ (pi0) nu_tau) < 2.4 x 10^(-6) at the
90% confidence level. This limit represents a significant improvement over the
previous limit.Comment: 9 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Measurement of the Isolated Photon Cross Section in p-pbar Collisions at sqrt{s}=1.96 TeV
The cross section for the inclusive production of isolated photons has been
measured in p anti-p collisions at sqrt{s}=1.96 TeV with the D0 detector at the
Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV
and have pseudorapidity |eta|<0.9. The cross section is compared with the
results from two next-to-leading order perturbative QCD calculations. The
theoretical predictions agree with the measurement within uncertainties.Comment: 7 pages, 5 figures, submitted to Phys.Lett.
The Physics of Star Cluster Formation and Evolution
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe
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