5,212 research outputs found
The Cepheid Distance Scale: recent progress in fundamental techniques
This review examines progress on the Pop I, fundamental-mode Cepheid distance
scale with emphasis on recent developments in geometric and quasi-geometric
techniques for Cepheid distance determination. Specifically I examine the
surface brightness method, interferometric pulsation method, and trigonometric
measurements. The three techniques are found to be in excellent agreement for
distance measures in the Galaxy. The velocity p-factor is of crucial importance
in the first two of these methods. A comparison of recent determinations of the
p-factor for Cepheids demonstrates that observational measures of p and
theoretical predictions agree within their uncertainties for Galactic Cepheids.Comment: An invited review at the Santa Fe, NM, conference -- Stellar
Pulsation: Challenges for Theory and Observation; May 31-June 5, 2009 10
pages, 8 figure
Permeability evolution across carbonate hosted normal fault zones
Acknowledgements: The authors would like to thank Total E&P and BG Group for project funding and support, and the Industry Technology Facilitator for facilitating the collaborative development (grant number 3322PSD). The authors would also like to express their gratitude to the Aberdeen Formation Evaluation Society and the College of Physical Sciences at the University of Aberdeen for partial financial support. Raymi Castilla (Total E&P), Fabrizio Agosta and Cathy Hollis are also thanked for their constructive comments and suggestions to improve the standard of this manuscript as are John Still and Colin Taylor (University of Aberdeen) for technical assistance in the laboratory. Piero Gianolla is thanked for his editorial handling of the manuscript.Peer reviewedPostprin
AGROINDUSTRIALIZATION IN EMERGING MARKETS: OVERVIEW AND STRATEGIC CONTEXT
This article offers an overview for a special issue on agroindustrialization. It reviews eleven articles analyzing the agroindustrialization process in Latin America and Asia. It sets out a conceptual framework from the organizational economics and strategic management literature to enhance the understanding of the process of agroindustrialization from a competitive strategy point of view.Agribusiness, Industrial Organization,
Factorised spatial representation learning: application in semi-supervised myocardial segmentation
The success and generalisation of deep learning algorithms heavily depend on
learning good feature representations. In medical imaging this entails
representing anatomical information, as well as properties related to the
specific imaging setting. Anatomical information is required to perform further
analysis, whereas imaging information is key to disentangle scanner variability
and potential artefacts. The ability to factorise these would allow for
training algorithms only on the relevant information according to the task. To
date, such factorisation has not been attempted. In this paper, we propose a
methodology of latent space factorisation relying on the cycle-consistency
principle. As an example application, we consider cardiac MR segmentation,
where we separate information related to the myocardium from other features
related to imaging and surrounding substructures. We demonstrate the proposed
method's utility in a semi-supervised setting: we use very few labelled images
together with many unlabelled images to train a myocardium segmentation neural
network. Specifically, we achieve comparable performance to fully supervised
networks using a fraction of labelled images in experiments on ACDC and a
dataset from Edinburgh Imaging Facility QMRI. Code will be made available at
https://github.com/agis85/spatial_factorisation.Comment: Accepted in MICCAI 201
Unusual nanostructures of "lattice matched" InP on AlInAs
We show that the morphology of the initial monolayers of InP on
Al0.48In0.52As grown by metalorganic vapor-phase epitaxy does not follow the
expected layer-by-layer growth mode of lattice-matched systems, but instead
develops a number of low-dimensional structures, e.g., quantum dots and wires.
We discuss how the macroscopically strain-free heteroepitaxy might be strongly
affected by local phase separation/alloying-induced strain and that the
preferred aggregation of adatom species on the substrate surface and reduced
wettability of InP on AlInAs surfaces might be the cause of the unusual (step)
organization and morpholog
The Play-Out Effect and Preference Reversals: Evidence For Noisy Maximization
In this paper, we document a play-out effect in preference reversal experiments. We compare data where preferences are elicited using (1) purely hypothetical gambles, (2) played-out, but unpaid gambles and (3) played-out gambles with truth-revealing monetary payments. We ask whether a model of stable preferences with random errors (e.g., expected utility with errors) can explain the data. The model is strongly rejected in data collected using purely hypothetical gambles. However, simply playing-out the gambles, even in the absence of payments, shifts the data pattern so that noisy maximization is no longer rejected. Inducing risk preferences using a lottery procedure, using monetary incentives or both shift the data pattern further so that noisy maximization achieves the best possible fit to the aggregate data. No model could fit the data better. We argue that play-out shifts the response pattern by inducing value because subjects can use outcomes to keep score. Induction or monetary payments create stronger induced values, shifting the pattern further
Low Earth orbital atomic oxygen environmental simulation facility for space materials evaluation
Simulation of low Earth orbit atomic oxygen for accelerated exposure in ground-based facilities is necessary for the durability evaluation of space power system component materials for Space Station Freedom (SSF) and future missions. A facility developed at the National Aeronautics and Space Administrations's (NASA) Lewis Research Center provides accelerated rates of exposure to a directed or scattered oxygen beam, vacuum ultraviolet (VUV) radiation, and offers in-situ optical characterization. The facility utilizes an electron-cyclotron resonance (ECR) plasma source to generate a low energy oxygen beam. Total hemispherical spectral reflectance of samples can be measured in situ over the wavelength range of 250 to 2500 nm. Deuterium lamps provide VUV radiation intensity levels in the 115 to 200 nm range of three to five equivalent suns. Retarding potential analyses show distributed ion energies below 30 electron volts (eV) for the operating conditions most suited for high flux, low energy testing. Peak ion energies are below the sputter threshold energy (approximately 30 eV) of the protective coatings on polymers that are evaluated in the facility, thus allowing long duration exposure without sputter erosion. Neutral species are expected to be at thermal energies of approximately .04 eV to .1 eV. The maximum effective flux level based on polyimide Kapton mass loss is 4.4 x 10 exp 6 atoms/((sq. cm)*s), thus providing a highly accelerated testing capability
Characterization of Heterorhabditis isolates by PCR amplification of segments of mtDNA and rDNA genes
Restriction digests of amplified DNA from the mitochondrial genome and the nuclear ribosomal internally transcribed spacer region have been evaluated as genetic markers for species groups in Heterorhabditis. Six RFLP profiles have been identified. These profiles supported groupings determined by cross-breeding studies and were in agreement with less definitive groupings based on other biochemical and molecular methods. Digestion patterns of both amplification products provided strong evidence for the recognition of species groups, which include Irish, NW European, tropical, and a H. bacteriophora complex. The H. bacteriophora complex could be further resolved into three genotypes represented by H. zealandica, the H. bacteriophora, Brecon (Australian) type isolate for H. bacteriophora, and a grouping composed of isolates NC1, V16, HI82, and HP88. All cultures obtained of the H. megidis isolate were identical to the NW European group. These results could be used to aid monitoring of field release of Heterorhabditis as well as allowing a rapid initial assessment of taxonomic grouping
Sex role inequality and marital stress
As the once clear definitions of marital roles become increasingly blurred by the new options available to women and as the incidence of divorce continues to rise, the relationship between sex role behavior and marital dissatisfaction has become an area of mounting concern. Many women today who find themselves in more traditional type marital roles are beginning to question if, in fact, their unequal role status within their marriage is truly satisfying
Characterization of \u3ci\u3eHeterorhabditis\u3c/i\u3e Isolates by PCR Amplification of Segments of mtDNA and rDNA Genes
Restriction digests of amplified DNA from the mitochondrial genome and the nuclear ribosomal internally transcribed spacer region have been evaluated as genetic markers for species groups in Heterorhabditis. Six RFLP profiles have been identified. These profiles supported groupings determined by cross-breeding studies and were in agreement with less definitive groupings based on other biochemical and molecular methods. Digestion patterns of both amplification products provided strong evidence for the recognition of species groups, which include Irish, NW European, tropical, and a H. bacteriophora complex. The H. bacteriophora complex could be further resolved into three genotypes represented by H. zealandica, the H. bacteriophora, Brecon (Australian) type isolate for H. bacteriophora, and a grouping composed of isolates NC1, V16, HI82, and HP88. All cultures obtained of the H. megidis isolate were identical to the NW European group. These results could be used to aid monitoring of field release of Heterorhabditis as well as allowing a rapid initial assessment of taxonomic grouping
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