5,721 research outputs found
Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
The Binary Population and Spectral Synthesis (BPASS) suite of binary stellar
evolution models and synthetic stellar populations provides a framework for the
physically motivated analysis of both the integrated light from distant stellar
populations and the detailed properties of those nearby. We present a new
version 2.1 data release of these models, detailing the methodology by which
BPASS incorporates binary mass transfer and its effect on stellar evolution
pathways, as well as the construction of simple stellar populations. We
demonstrate key tests of the latest BPASS model suite demonstrating its ability
to reproduce the colours and derived properties of resolved stellar
populations, including well- constrained eclipsing binaries. We consider
observational constraints on the ratio of massive star types and the
distribution of stellar remnant masses. We describe the identification of
supernova progenitors in our models, and demonstrate a good agreement to the
properties of observed progenitors. We also test our models against photometric
and spectroscopic observations of unresolved stellar populations, both in the
local and distant Universe, finding that binary models provide a
self-consistent explanation for observed galaxy properties across a broad
redshift range. Finally, we carefully describe the limitations of our models,
and areas where we expect to see significant improvement in future versions.Comment: 69 pages, 45 figures. Accepted for publication in PASA. Accompanied
by a full, documented data release at http://bpass.auckland.ac.nz and
http://warwick.ac.uk/bpas
The origin of carbon isotope vital effects in coccolith calcite
Calcite microfossils are widely used to study climate and oceanography in Earth’s geological past. Coccoliths, readily preserved calcite plates produced by a group of single-celled surface-ocean dwelling algae called coccolithophores, have formed a significant fraction of marine sediments since the Late Triassic. However, unlike the shells of foraminifera, their zooplankton counterparts, coccoliths remain underused in palaeo-reconstructions. Precipitated in an intracellular chemical and isotopic microenvironment, coccolith calcite exhibits large and enigmatic departures from the isotopic composition of abiogenic calcite, known as vital effects. Here we show that the calcification to carbon fixation ratio determines whether coccolith calcite is isotopically heavier or lighter than abiogenic calcite, and that the size of the deviation is determined by the degree of carbon utilization. We discuss the theoretical potential for, and current limitations of, coccolith-based CO2 paleobarometry, that may eventually facilitate use of the ubiquitous and geologically extensive sedimentary archive
The ACIGA Data Analysis programme
The Data Analysis programme of the Australian Consortium for Interferometric
Gravitational Astronomy (ACIGA) was set up in 1998 by the first author to
complement the then existing ACIGA programmes working on suspension systems,
lasers and optics, and detector configurations. The ACIGA Data Analysis
programme continues to contribute significantly in the field; we present an
overview of our activities.Comment: 10 pages, 0 figures, accepted, Classical and Quantum Gravity,
(Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves,
Tirrenia, Pisa, Italy, 6-11 July 2003
Causes of Differences in Soil Series of the Missouri River Bottomlands of Monona County
The current soil survey of Monona County has revealed many differences in the alluvial deposits occurring in the Missouri River bottomlands. As a consequence the soils developed from these different deposits show numerous dissimilarities. It is the purpose of this paper to describe and explain the causes of the differences encountered. The principal factors in soil formation are climate, organisms, topography, parent material and time. In the Missouri River bottomlands of Monona County it can be assumed that climate and organisms are not important causes of soil differences. In general, differences in topography are closely related to differences in parent material. Thus parent material or time of deposition or both, must be the principal cause or causes of soil differences. The soils found on the Missouri River bottomlands are, for the most part, formed from alluvial materials. Some coarser alluvium may have been resorted by wind action subsequent to deposition but areas showing evidence of wind action are not extensive. The principal source of alluvium is the Missouri River; next, the tributary rivers and streams; and, of least importance, the steep bluffs that form the sides of the valley
Periorbital edema secondary to imatinib mesylate
Collin M McClelland, George J Harocopos, Philip L CusterSchool of Medicine, Washington University, St. Louis, MO, USAAbstract: Imatinib mesylate (Gleevec®) is a well-established pharmacologic treatment for all phases of chronic myeloid leukemia and for advanced gastrointestinal stromal tumors (GISTs). Edema-related side effects are relatively common in imatinib therapy with the periocular skin representing one of the most common sites for localized edema. While the adverse effect of periorbital edema with imatinib is well documented in the oncology literature, there is limited reference to this common reaction in the ophthalmology literature. We report two patients with upper eyelid edema associated with imatinib therapy who required surgical intervention to ameliorate significant visual field obstruction. We highlight the details of each case including the histopathologic findings of excised redundant skin followed by a thorough review of the literature on imatinib related periorbital edema.Keywords: imatinib mesylate, gleevec, edema, periorbital edema, tyrosine kinase inhibito
Uncertainty in multitask learning: joint representations for probabilistic MR-only radiotherapy planning
Multi-task neural network architectures provide a mechanism that jointly
integrates information from distinct sources. It is ideal in the context of
MR-only radiotherapy planning as it can jointly regress a synthetic CT (synCT)
scan and segment organs-at-risk (OAR) from MRI. We propose a probabilistic
multi-task network that estimates: 1) intrinsic uncertainty through a
heteroscedastic noise model for spatially-adaptive task loss weighting and 2)
parameter uncertainty through approximate Bayesian inference. This allows
sampling of multiple segmentations and synCTs that share their network
representation. We test our model on prostate cancer scans and show that it
produces more accurate and consistent synCTs with a better estimation in the
variance of the errors, state of the art results in OAR segmentation and a
methodology for quality assurance in radiotherapy treatment planning.Comment: Early-accept at MICCAI 2018, 8 pages, 4 figure
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