50 research outputs found
The 3D Structure of N132D in the LMC: A Late-Stage Young Supernova Remnant
We have used the Wide Field Spectrograph (WiFeS) on the 2.3m telescope at
Siding Spring Observatory to map the [O III] 5007{\AA} dynamics of the young
oxygen-rich supernova remnant N132D in the Large Magellanic Cloud. From the
resultant data cube, we have been able to reconstruct the full 3D structure of
the system of [O III] filaments. The majority of the ejecta form a ring of
~12pc in diameter inclined at an angle of 25 degrees to the line of sight. We
conclude that SNR N132D is approaching the end of the reverse shock phase
before entering the fully thermalized Sedov phase of evolution. We speculate
that the ring of oxygen-rich material comes from ejecta in the equatorial plane
of a bipolar explosion, and that the overall shape of the SNR is strongly
influenced by the pre-supernova mass loss from the progenitor star. We find
tantalizing evidence of a polar jet associated with a very fast oxygen-rich
knot, and clear evidence that the central star has interacted with one or more
dense clouds in the surrounding ISM.Comment: Accepted for Publication in Astrophysics & Space Science, 18pp, 8
figure
Predicting management development and learning behaviour in New Zealand SMEs
Despite concern on the part of policy makers to raise managerial capability in SMEs, there is little evidence on the key drivers of owner-manager participation in management development programmes. The authors argue that such participation is poorly understood. The paper develops a predictive model of the drivers of participation in sources of learning by owner-managers. It tests a theoretical model, based on the small firm as a learning organization, which posits that participation is driven by owner-managers\u27 learning orientation and the extent of their belief in self-improvement. The implications of the results are discussed in light of the provision of management development programmes. <br /
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Parental origin of sequence variants associated with complex diseases
To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldEffects of susceptibility variants may depend on from which parent they are inherited. Although many associations between sequence variants and human traits have been discovered through genome-wide associations, the impact of parental origin has largely been ignored. Here we show that for 38,167 Icelanders genotyped using single nucleotide polymorphism (SNP) chips, the parental origin of most alleles can be determined. For this we used a combination of genealogy and long-range phasing. We then focused on SNPs that associate with diseases and are within 500 kilobases of known imprinted genes. Seven independent SNP associations were examined. Five-one with breast cancer, one with basal-cell carcinoma and three with type 2 diabetes-have parental-origin-specific associations. These variants are located in two genomic regions, 11p15 and 7q32, each harbouring a cluster of imprinted genes. Furthermore, we observed a novel association between the SNP rs2334499 at 11p15 and type 2 diabetes. Here the allele that confers risk when paternally inherited is protective when maternally transmitted. We identified a differentially methylated CTCF-binding site at 11p15 and demonstrated correlation of rs2334499 with decreased methylation of that site.info:eu-repo/grantAgreement/EC/FP7/21807
Meta-analysis of type 2 Diabetes in African Americans Consortium
Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR) = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe
Novel Loci for Adiponectin Levels and Their Influence on Type 2 Diabetes and Metabolic Traits : A Multi-Ethnic Meta-Analysis of 45,891 Individuals
J. Kaprio, S. Ripatti ja M.-L. Lokki työryhmien jäseniä.Peer reviewe
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Effects of magmatic processes on the potential Yucca Mountain repository: Field and computational studies
Assessing the risk of future magmatic activity at a potential Yucca Mountain radioactive waste repository requires, in addition to event probabilities, some knowledge of the consequences of such activity. Magmatic consequences are divided into an eruptive component, which pertains to the possibility of radioactive waste being erupted onto the surface of Yucca Mountain, and a subsurface component, which occurs whether there is an accompanying eruption or not. The subsurface component pertains to a suite of processes such as hydrothermal activity, changes in country rock properties, and long term alteration of the hydrologic flow field which change the waste isolation system. This paper is the second in a series describing progress on studies of the effects of magmatic activity. We describe initial results of field analog studies at small volume basaltic centers where detailed measurements are being conducted of the amount of wall rock debris that can be erupted as a function of depth in the volcanic plumbing system. Constraints from field evidence of wall rock entrainment mechanisms are also discussed. Evidence is described for a mechanism of producing subhorizontal sills versus subvertical dikes, an issue that is important for assessing subsurface effects. Finally, new modeling techniques, which are being developed in order to capture the three dimensional complexities of real geologic situations in subsurface effects, are described
Applying search theory to determine the feasibility of eradicating an invasive population in natural environments
The detectability of invasive organisms influences the feasibility of eradicating an infestation. Search theory offers a framework for defining and measuring detectability, taking account of searcher ability, biological factors and the search environment. In this paper, search theory concepts are incorporated into a population model, and the costs of search and control are calculated as functions of the amount of search effort (the decision variable). Simulations are performed on a set of weed scenarios in a natural environment, involving different combinations of plant longevity, seed longevity and plant fecundity. Results provide preliminary estimates of the cost and duration of eradication programs to assist in prioritising weeds for control. The analysis shows that the success of an eradication program depends critically on the detectability of the target plant, the effectiveness of the control method, the labour requirements for search and control, and the germination rate of the plant. Copyright 2007 The Authors Journal compilation 2007 Australian Agricultural and Resource Economics Society Inc. .