527 research outputs found
Ionization of Infalling Gas
H-alpha emission from neutral halo clouds probes the radiation and
hydrodynamic conditions in the halo. Armed with such measurements, we can
explore how radiation escapes from the Galactic plane and how infalling gas can
survive a trip through the halo. The Wisconsin H-Alpha Mapper (WHAM) is one of
the most sensitive instruments for detecting and mapping optical emission from
the ISM. Here, we present recent results exploring the ionization of two
infallling high-velocity complexes. First, we report on our progress mapping
H-alpha emission covering the full extent of Complex A. Intensities are faint
(<100 mR; EM <0.2 pc cm^-6 but correlate on the sky and in velocity with 21-cm
emission. Second, we explore the ionized component of some Anti-Center Complex
clouds studied by Peek et al. (2007) that show dynamic shaping from interaction
with the Galactic halo.Comment: 4 pages, 2 figures; to appear in proceedings of "The Role of
Disk-Halo Interaction in Galaxy Evolution: Outflow vs Infall?" held in
Espinho, Portugal during 2008 Augus
A long hard look at MCG-6-30-15 with XMM-Newton and BeppoSAX
We summarise the primary results from a 320 ks observation of the bright
Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and Beppo-SAX.Comment: 4 pages, 6 figures. Proc. of the meeting: "The Restless High-Energy
Universe" (Amsterdam, The Netherlands), E.P.J. van den Heuvel, J.J.M. in 't
Zand, and R.A.M.J. Wijers Ed
Comparison At The First Prenatal Visit of the Maternal Dietary Intakes of Smokers With Non-Smokers in a Large Maternity Hospital: A Cross-Sectional Study
Using detailed dietary and supplement questionnaires in early pregnancy, we compared the dietary intakes of micronutrients and macronutrients at the first prenatal visit of women who reported continuing to smoke during pregnancy with the intakes of women who were non-smokers
ANN-based energy reconstruction procedure for TACTIC gamma-ray telescope and its comparison with other conventional methods
The energy estimation procedures employed by different groups, for
determining the energy of the primary -ray using a single atmospheric
Cherenkov imaging telescope, include methods like polynomial fitting in SIZE
and DISTANCE, general least square fitting and look-up table based
interpolation. A novel energy reconstruction procedure, based on the
utilization of Artificial Neural Network (ANN), has been developed for the
TACTIC atmospheric Cherenkov imaging telescope. The procedure uses a 3:30:1 ANN
configuration with resilient backpropagation algorithm to estimate the energy
of a -ray like event on the basis of its image SIZE, DISTANCE and
zenith angle. The new ANN-based energy reconstruction method, apart from
yielding an energy resolution of 26%, which is comparable to that of
other single imaging telescopes, has the added advantage that it considers
zenith angle dependence as well. Details of the ANN-based energy estimation
procedure along with its comparative performance with other conventional energy
reconstruction methods are presented in the paper and the results indicate that
amongst all the methods considered in this work, ANN method yields the best
results. The performance of the ANN-based energy reconstruction has also been
validated by determining the energy spectrum of the Crab Nebula in the energy
range 1-16 TeV, as measured by the TACTIC telescope.Comment: 23pages, 9 figures Accepted for publication in NIM
Magnetoresistance of Three-Constituent Composites: Percolation Near a Critical Line
Scaling theory, duality symmetry, and numerical simulations of a random
network model are used to study the magnetoresistance of a
metal/insulator/perfect conductor composite with a disordered columnar
microstructure. The phase diagram is found to have a critical line which
separates regions of saturating and non-saturating magnetoresistance. The
percolation problem which describes this line is a generalization of
anisotropic percolation. We locate the percolation threshold and determine the
t = s = 1.30 +- 0.02, nu = 4/3 +- 0.02, which are the same as in
two-constituent 2D isotropic percolation. We also determine the exponents which
characterize the critical dependence on magnetic field, and confirm numerically
that nu is independent of anisotropy. We propose and test a complete scaling
description of the magnetoresistance in the vicinity of the critical line.Comment: Substantially revised version; description of behavior in finite
magnetic fields added. 7 pages, 7 figures, submitted to PR
Dynamical Mean-Field Theory of Electron-Phonon Interactions in Correlated Systems: Application to Isotope Effects on Electronic Properties
We use a recently developed formalism (combining an adiabatic expansion and
dynamical mean-field theory) to obtain expressions for isotope effects on
electronic properties in correlated systems. As an example we calculate the
isotope effect on electron effective mass for the Holstein model as a function
of electron-phonon interaction strength and doping. Our systematic expansion
generates diagrams neglected in previous studies, which turn out to give the
dominant contributions. The isotope effect is small unless the system is near a
lattice instability. We compare this to experiment.Comment: 6 pages, 4 figures; added discussion of isotope effect away from half
fillin
Observations of TeV gamma-rays from Mrk 421 during Dec. 2005 to Apr. 2006 with the TACTIC telescope
The TACTIC -ray telescope has observed Mrk 421 on 66 clear nights
from Dec. 07, 2005 to Apr. 30, 2006, totalling 202 hours of on-source
observations. Here, we report the detection of flaring activity from the source
at 1 TeV energy and the time-averaged differential -ray spectrum
in the energy range 1-11 TeV for the data taken between Dec. 27, 2005 to Feb.
07, 2006 when the source was in a relatively higher state as compared to the
rest of the observation period. Analysis of this data spell, comprising about
97h reveals the presence of a -ray signal with
daily flux of 1 Crab unit on several days. A pure power law spectrum with
exponent as well as a power law spectrum with an exponential
cutoff and are found to provide
reasonable fits to the inferred differential spectrum within statistical
uncertainties. We believe that the TeV light curve presented here, for nearly 5
months of extensive coverage, as well as the spectral information at
-ray energies of 5 TeV provide a useful input for other groups
working in the field of -ray astronomy.Comment: 13pages,4figures; Accepted for publication in Astroparticle Physic
The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour
Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect
Pulsar-wind nebulae and magnetar outflows: observations at radio, X-ray, and gamma-ray wavelengths
We review observations of several classes of neutron-star-powered outflows:
pulsar-wind nebulae (PWNe) inside shell supernova remnants (SNRs), PWNe
interacting directly with interstellar medium (ISM), and magnetar-powered
outflows. We describe radio, X-ray, and gamma-ray observations of PWNe,
focusing first on integrated spectral-energy distributions (SEDs) and global
spectral properties. High-resolution X-ray imaging of PWNe shows a bewildering
array of morphologies, with jets, trails, and other structures. Several of the
23 so far identified magnetars show evidence for continuous or sporadic
emission of material, sometimes associated with giant flares, and a few
possible "magnetar-wind nebulae" have been recently identified.Comment: 61 pages, 44 figures (reduced in quality for size reasons). Published
in Space Science Reviews, "Jets and Winds in Pulsar Wind Nebulae, Gamma-ray
Bursts and Blazars: Physics of Extreme Energy Release
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
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