156 research outputs found
An Essay on the Vicissitudes of Civil Society with Special Reference to Scotland in the Eighteenth Century
Symposium: Law and Civil Societ
Joyce Piell Wexler, Who Paid for Modernism?: Art, Money, and the Fiction of Conrad, Joyce, and Lawrence
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44647/1/10824_2004_Article_155313.pd
Potential Melting of Extrasolar Planets by Tidal Dissipation
Tidal heating on Io due to its finite eccentricity was predicted to drive
surface volcanic activity, which was subsequently confirmed by the
spacecrafts. Although the volcanic activity in Io is more
complex, in theory volcanism can be driven by runaway melting in which the
tidal heating increases as the mantle thickness decreases. We show that this
runaway melting mechanism is generic for a composite planetary body with liquid
core and solid mantle, provided that (i) the mantle rigidity, , is
comparable to the central pressure, i.e.
for a body with density , surface gravitational acceleration , and
radius , (ii) the surface is not molten, (iii) tides deposit
sufficient energy, and (iv) the planet has nonzero eccentricity. We calculate
the approximate liquid core radius as a function of ,
and find that more than of the core will melt due to this runaway for
. From all currently confirmed exoplanets, we
find that the terrestrial planets in the L98-59 system are the most promising
candidates for sustaining active volcanism. However, uncertainties regarding
the quality factors and the details of tidal heating and cooling mechanisms
prohibit definitive claims of volcanism on any of these planets. We generate
synthetic transmission spectra of these planets assuming Venus-like atmospheric
compositions with an additional 5, 50, and SO component, which is a
tracer of volcanic activity. We find a preference for a
model with SO with 5-10 transits with for L98-59bcd.Comment: 16 pages, 8 Figures, accepted for publication in Ap
Electron correlation vs. stabilization: A two-electron model atom in an intense laser pulse
We study numerically stabilization against ionization of a fully correlated
two-electron model atom in an intense laser pulse. We concentrate on two
frequency regimes: very high frequency, where the photon energy exceeds both,
the ionization potential of the outer {\em and} the inner electron, and an
intermediate frequency where, from a ``single active electron''-point of view
the outer electron is expected to stabilize but the inner one is not. Our
results reveal that correlation reduces stabilization when compared to results
from single active electron-calculations. However, despite this destabilizing
effect of electron correlation we still observe a decreasing ionization
probability within a certain intensity domain in the high-frequency case. We
compare our results from the fully correlated simulations with those from
simpler, approximate models. This is useful for future work on ``real''
more-than-one electron atoms, not yet accessible to numerical {\em ab initio}
methods.Comment: 8 pages, 8 figures in an extra ps-file, submitted to Phys. Rev. A,
updated references and shortened introductio
Propagating semantic information in biochemical network models
<p>Abstract</p> <p>Background</p> <p>To enable automatic searches, alignments, and model combination, the elements of systems biology models need to be compared and matched across models. Elements can be identified by machine-readable biological annotations, but assigning such annotations and matching non-annotated elements is tedious work and calls for automation.</p> <p>Results</p> <p>A new method called "semantic propagation" allows the comparison of model elements based not only on their own annotations, but also on annotations of surrounding elements in the network. One may either propagate feature vectors, describing the annotations of individual elements, or quantitative similarities between elements from different models. Based on semantic propagation, we align partially annotated models and find annotations for non-annotated model elements.</p> <p>Conclusions</p> <p>Semantic propagation and model alignment are included in the open-source library semanticSBML, available on sourceforge. Online services for model alignment and for annotation prediction can be used at <url>http://www.semanticsbml.org</url>.</p
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
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