442 research outputs found
A Search for Ionized Gas in the Draco and Ursa Minor Dwarf Spheroidal Galaxies
The Wisconsin H Alpha Mapper has been used to set the first deep upper limits
on the intensity of diffuse H alpha emission from warm ionized gas in the Local
Group dwarf spheroidal galaxies (dSphs) Draco and Ursa Minor. Assuming a
velocity dispersion of 15 km/s for the ionized gas, we set limits for the H
alpha intensity of less or equal to 0.024 Rayleighs and less or equal to 0.021
Rayleighs for the Draco and Ursa Minor dSphs, respectively, averaged over our 1
degree circular beam. Adopting a simple model for the ionized interstellar
medium, these limits translate to upper bounds on the mass of ionized gas of
approximately less than 10% of the stellar mass, or approximately 10 times the
upper limits for the mass of neutral hydrogen. Note that the Draco and Ursa
Minor dSphs could contain substantial amounts of interstellar gas, equivalent
to all of the gas injected by dying stars since the end of their main star
forming episodes more than 8 Gyr in the past, without violating these limits on
the mass of ionized gas.Comment: 10 pages, 2 figures, AASTeX two-column format. Accepted for
publication in The Astrophysical Journa
Gene validation and remodelling using proteogenomics of Phytophthora cinnamomi, the causal agent of Dieback
Phytophthora cinnamomi is a pathogenic oomycete that causes plant dieback disease
across a range of natural ecosystems and in many agriculturally important crops on a
global scale. An annotated draft genome sequence is publicly available (JGI Mycocosm)
and suggests 26,131 gene models. In this study, soluble mycelial, extracellular
(secretome), and zoospore proteins of P. cinnamomi were exploited to refine the genome
by correcting gene annotations and discovering novel genes. By implementing the
diverse set of sub-proteomes into a generated proteogenomics pipeline, we were
able to improve the P. cinnamomi genome annotation. Liquid chromatography mass
spectrometry was used to obtain high confidence peptides with spectral matching
to both the annotated genome and a generated 6-frame translation. Two thousand
seven hundred sixty-four annotations from the draft genome were confirmed by spectral
matching. Using a proteogenomic pipeline, mass spectra were used to edit the
P. cinnamomi genome and allowed identification of 23 new gene models and 60
edited gene features using high confidence peptides obtained by mass spectrometry,
suggesting a rate of incorrect annotations of 3% of the detectable proteome. The
novel features were further validated by total peptide support, alongside functional
analysis including the use of Gene Ontology and functional domain identification. We
demonstrated the use of spectral data in combination with our proteogenomics pipeline
can be used to improve the genome annotation of important plant diseases and identify
missed genes. This study presents the first use of spectral data to edit and manually
annotate an oomycete pathogen
Dwarf Cepheids in the Carina Dwarf Spheroidal Galaxy
We have discovered 20 dwarf Cepheids (DC) in the Carina dSph galaxy from the
analysis of individual CCD images obtained for a deep photometric study of the
system. These short-period pulsating variable stars are by far the most distant
(~100 kpc) and faintest (V ~ 23.0) DCs known. The Carina DCs obey a
well-defined period-luminosity relation, allowing us to readily distinguish
between overtone and fundamental pulsators in nearly every case. Unlike RR Lyr
stars, the pulsation mode turns out to be uncorrelated with light-curve shape,
nor do the overtone pulsators tend towards shorter periods compared to the
fundamental pulsators. Using the period-luminosity (PL) relations from Nemec et
al. (1994 AJ, 108, 222) and McNamara (1995, AJ, 109, 1751), we derive (m-M)_0 =
20.06 +/- 0.12, for E(B-V) = 0.025 and [Fe/H] = -2.0, in good agreement with
recent, independent estimates of the distance/reddening of Carina. The error
reflects the uncertainties in the DC distance scale, and in the metallicity and
reddening of Carina. The frequency of DCs among upper main sequence stars in
Carina is approximately 3%. The ratio of dwarf Cepheids to RR Lyr stars in
Carina is 0.13 +/- 0.10, though this result is highly sensitive to the
star-formation history of Carina and the evolution of the Horizontal Branch. We
discuss how DCs may be useful to search effectively for substructure in the
Galactic halo out to Galactocentric distances of ~100 kpc.Comment: 20 pages of text, 7 figure
Proteomic analysis of Rhizoctonia solani identifies infection-specific, redox associated proteins and insight into adaptation to different plant hosts
Rhizoctonia solani is an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about how R. solani causes disease. This study capitalises on recent genomic studies by applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Many of the proteins found in the culture filtrate had predicted functions relating to modification of the plant cell wall, a major activity required for pathogenesis on the plant host, including a number found only under infection conditions. Other infection related proteins included a high proportion of proteins with redox associated functions and many novel proteins without functional classification. The majority of infection only proteins tested were confirmed to show transcript up-regulation during infection including a thaumatin which increased susceptibility to R. solani when expressed in Nicotiana benthamiana. In addition, analysis of expression during infection of different plant hosts highlighted how the infection strategy of this broad host range pathogen can be adapted to the particular host being encountered. Data are available via ProteomeXchange with identifier PXD002806
Mass-spectrometry data for Rhizoctonia solani proteins produced during infection of wheat and vegetative growth
© 2016. Rhizoctonia solani is an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato, legumes and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about how R. solani causes disease. The data described in this article is derived from applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Comparisons of the data for sample types in this set will be useful to identify metabolic pathway changes as the fungus switches from saprophytic to a pathogenic lifestyle or pathogenicity related proteins contributing to the ability to cause disease on wheat. The data set is deposited in the PRIDE archive under identifier PRIDE: PXD002806
The relevance of outsourcing and leagile strategies in performance optimization of an integrated process planning and scheduling
Over the past few years growing global competition has forced the manufacturing industries to upgrade their old production strategies with the modern day approaches. As a result, recent interest has been developed towards finding an appropriate policy that could enable them to compete with others, and facilitate them to emerge as a market winner. Keeping in mind the abovementioned facts, in this paper the authors have proposed an integrated process planning and scheduling model inheriting the salient features of outsourcing, and leagile principles to compete in the existing market scenario. The paper also proposes a model based on leagile principles, where the integrated planning management has been practiced. In the present work a scheduling problem has been considered and overall minimization of makespan has been aimed. The paper shows the relevance of both the strategies in performance enhancement of the industries, in terms of their reduced makespan. The authors have also proposed a new hybrid Enhanced Swift Converging Simulated Annealing (ESCSA) algorithm, to solve the complex real-time scheduling problems. The proposed algorithm inherits the prominent features of the Genetic Algorithm (GA), Simulated Annealing (SA), and the Fuzzy Logic Controller (FLC). The ESCSA algorithm reduces the makespan significantly in less computational time and number of iterations. The efficacy of the proposed algorithm has been shown by comparing the results with GA, SA, Tabu, and hybrid Tabu-SA optimization methods
Forced and self-excited oscillations of an optomechanical cavity
We experimentally study forced and self oscillations of an optomechanical
cavity which is formed between a fiber Bragg grating that serves as a static
mirror and between a freely suspended metallic mechanical resonator that serves
as a moving mirror. In the domain of small amplitude mechanical oscillations,
we find that the optomechanical coupling is manifested as changes in the
effective resonance frequency, damping rate and cubic nonlinearity of the
mechanical resonator. Moreover, self oscillations of the micromechanical mirror
are observed above a certain optical power threshold. A comparison between the
experimental results and a theoretical model that we have recently presented
yields a good agreement. The comparison also indicates that the dominant
optomechanical coupling mechanism is the heating of the metallic mirror due to
optical absorption.Comment: 11 pages, 6 figure
The Star Clusters in the Starburst Irregular Galaxy NGC 1569
We examine star clusters in the irregular, starburst galaxy NGC 1569 from HST
images. In addition to the two known super star clusters, we identify 45 other
clusters that are compact but resolved. Integrated UVI colors of the clusters
span a large range, and suggest that ages range from 3 Myrs to 1 Gyr. However,
most of the clusters were formed at the tail end of the recent starburst.
Numerous clusters in addition to the know super star clusters are similar in
luminosity to a small globular cluster. We examined the radial surface
brightness of four of the clusters. Their half-light radii and core radii are
in the range observed in present-day globular clusters. Therefore, conditions
that produced the recent starburst have also been those necessary for producing
compact, bright star clusters.
We examine resolved stars in the outer parts of the two super star clusters.
Cluster A is dominated by bright blue stars with a small population of red
supergiants. Sub-components A1 and A2 have similar colors and a two-dimensional
color map does not offer evidence that one component is dominated by red
supergiants and the other not. The contradiction of the presence of red super-
giants with Wolf-Rayet stars may instead not be a contradiction at all since
there coexistence in a coeval population is not inconsistent with the evolution
of massive stars. Cluster B is dominated by red supergiants, and this is
confirmed by the presence of the stellar CO absorption feature in an integrated
spectrum. The various age indicators are consistent with a picture in which
cluster B is of order 10--20 Myrs old, and cluster A is >4-5 Myrs old.Comment: To be published in AJ, November 200
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