2,985 research outputs found
A Computational Method for the Rate Estimation of Evolutionary Transpositions
Genome rearrangements are evolutionary events that shuffle genomic
architectures. Most frequent genome rearrangements are reversals,
translocations, fusions, and fissions. While there are some more complex genome
rearrangements such as transpositions, they are rarely observed and believed to
constitute only a small fraction of genome rearrangements happening in the
course of evolution. The analysis of transpositions is further obfuscated by
intractability of the underlying computational problems.
We propose a computational method for estimating the rate of transpositions
in evolutionary scenarios between genomes. We applied our method to a set of
mammalian genomes and estimated the transpositions rate in mammalian evolution
to be around 0.26.Comment: Proceedings of the 3rd International Work-Conference on
Bioinformatics and Biomedical Engineering (IWBBIO), 2015. (to appear
The stability of modified gravity models
Conditions for the existence and stability of de Sitter space in modified
gravity are derived by considering inhomogeneous perturbations in a
gauge-invariant formalism. The stability condition coincides with the
corresponding condition for stability with respect to homogeneous
perturbations, while this is not the case in scalar-tensor gravity. The
stability criterion is applied to various modified gravity models of the early
and the present universe.Comment: 22 pages, LaTeX, to appear in Phys. Rev.
Rate of photon production from hot hadronic matter
Thermal photon emission rates from hot hadronic matter are studied to order
, where indicates a strong-interaction coupling constant.
Radiative decay of mesons, Compton and annihilation processes for hadrons, and
bremsstrahlung reactions are all considered. Compared to the standard rates
from the literature, one finds two orders of magnitude increase for low photon
energies stemming mainly from bremsstrahlung and then a modest increase (factor
of 2) for intermediate and high energy photons owing to radiative decays for a
variety of mesons and from other reactions involving strangeness. These results
could have important consequences for electromagnetic radiation studies at
RHIC.Comment: 5 pages LaTeX, 4 Postscript figure
The state of Denmark: what voters can tell us about the future of the Danish ideal
Denmark is often held up as an ideal society with a well-functioning welfare state, low levels of corruption, and high levels of social and political stability. But behind this perception, the country is facing up to a number of important challenges. Drawing on a new book, Rune Stubager, Kasper M. Hansen, Michael S. Lewis-Beck and Richard Nadeau explain how voters have responded to key macrosocial challenges since the 1970s and assess where this leaves the future of the Danish ideal
TRIDENT: an Infrared Differential Imaging Camera Optimized for the Detection of Methanated Substellar Companions
A near-infrared camera in use at the Canada-France-Hawaii Telescope (CFHT)
and at the 1.6-m telescope of the Observatoire du Mont-Megantic is described.
The camera is based on a Hawaii-1 1024x1024 HgCdTe array detector. Its main
feature is to acquire three simultaneous images at three wavelengths across the
methane absorption bandhead at 1.6 microns, enabling, in theory, an accurate
subtraction of the stellar point spread function (PSF) and the detection of
faint close methanated companions. The instrument has no coronagraph and
features fast data acquisition, yielding high observing efficiency on bright
stars. The performance of the instrument is described, and it is illustrated by
laboratory tests and CFHT observations of the nearby stars GL526, Ups And and
Chi And. TRIDENT can detect (6 sigma) a methanated companion with delta H = 9.5
at 0.5" separation from the star in one hour of observing time. Non-common path
aberrations and amplitude modulation differences between the three optical
paths are likely to be the limiting factors preventing further PSF attenuation.
Instrument rotation and reference star subtraction improve the detection limit
by a factor of 2 and 4 respectively. A PSF noise attenuation model is presented
to estimate the non-common path wavefront difference effect on PSF subtraction
performance.Comment: 41 pages, 16 figures, accepted for publication in PAS
Management of Occupational Manganism: Consensus of an Experts' Panel
Studies and Research Projects / Report R-417, Montréal, IRSST http://www.irsst.qc.ca/en/_publicationirsst_100134.html
(Lucchini R was a member of the Expert Panel
The Exact Evolution Equation of the Curvature Perturbation for Closed Universe
As is well known, the exact evolution equation of the curvature perturbation
plays a very important role in investigation of the inflation power spectrum of
the flat universe. However, its corresponding exact extension for the non-flat
universes has not yet been given out clearly. The interest in the non-flat,
specially closed, universes is being aroused recently. The need of this
extension is pressing. We start with most elementary physical consideration and
obtain finally this exact evolution equation of the curvature perturbation for
the non-flat universes, as well as the evolutionary controlling parameter and
the exact expression of the variable mass in this equation. We approximately do
a primitive and immature analysis on the power spectrum of non-flat universes.
This analysis shows that this exact evolution equation of the curvature
perturbation for the non-flat universes is very complicated, and we need to do
a lot of numerical and analytic work for this new equation in future in order
to judge whether the universe is flat or closed by comparison between theories
and observations.Comment: 10 pages, no figures, Late
Word Embeddings for Entity-annotated Texts
Learned vector representations of words are useful tools for many information
retrieval and natural language processing tasks due to their ability to capture
lexical semantics. However, while many such tasks involve or even rely on named
entities as central components, popular word embedding models have so far
failed to include entities as first-class citizens. While it seems intuitive
that annotating named entities in the training corpus should result in more
intelligent word features for downstream tasks, performance issues arise when
popular embedding approaches are naively applied to entity annotated corpora.
Not only are the resulting entity embeddings less useful than expected, but one
also finds that the performance of the non-entity word embeddings degrades in
comparison to those trained on the raw, unannotated corpus. In this paper, we
investigate approaches to jointly train word and entity embeddings on a large
corpus with automatically annotated and linked entities. We discuss two
distinct approaches to the generation of such embeddings, namely the training
of state-of-the-art embeddings on raw-text and annotated versions of the
corpus, as well as node embeddings of a co-occurrence graph representation of
the annotated corpus. We compare the performance of annotated embeddings and
classical word embeddings on a variety of word similarity, analogy, and
clustering evaluation tasks, and investigate their performance in
entity-specific tasks. Our findings show that it takes more than training
popular word embedding models on an annotated corpus to create entity
embeddings with acceptable performance on common test cases. Based on these
results, we discuss how and when node embeddings of the co-occurrence graph
representation of the text can restore the performance.Comment: This paper is accepted in 41st European Conference on Information
Retrieva
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