9,087 research outputs found
maigesPack: A Computational Environment for Microarray Data Analysis
Microarray technology is still an important way to assess gene expression in
molecular biology, mainly because it measures expression profiles for thousands
of genes simultaneously, what makes this technology a good option for some
studies focused on systems biology. One of its main problem is complexity of
experimental procedure, presenting several sources of variability, hindering
statistical modeling. So far, there is no standard protocol for generation and
evaluation of microarray data. To mitigate the analysis process this paper
presents an R package, named maigesPack, that helps with data organization.
Besides that, it makes data analysis process more robust, reliable and
reproducible. Also, maigesPack aggregates several data analysis procedures
reported in literature, for instance: cluster analysis, differential
expression, supervised classifiers, relevance networks and functional
classification of gene groups or gene networks
Shape, spin and baryon fraction of clusters in the MareNostrum Universe
The MareNostrum Universe is one of the largest cosmological
SPH simulation done so far. It consists of dark and
gas particles in a box of 500 Mpc on a side. Here we study
the shapes and spins of the dark matter and gas components of the 10,000 most
massive objects extracted from the simulation as well as the gas fraction in
those objects. We find that the shapes of objects tend to be prolate both in
the dark matter and gas. There is a clear dependence of shape on halo mass, the
more massive ones being less spherical than the less massive objects. The gas
distribution is nevertheless much more spherical than the dark matter, although
the triaxiality parameters of gas and dark matter differ only by a few percent
and it increases with cluster mass. The spin parameters of gas and dark matter
can be well fitted by a lognormal distribution function. On average, the spin
of gas is 1.4 larger than the spin of dark matter. We find a similar behavior
for the spins at higher redshifts, with a slightly decrease of the spin ratios
to 1.16 at The cosmic normalized baryon fraction in the entire cluster
sample ranges from , at to at . At both
redshifts we find a slightly, but statistically significant decrease of
with cluster mass.Comment: 7 pages, 6 figures. Accepted for publication in The Astrophysical
Journa
Vacuum solutions with nontrivial boundaries for the Einstein-Gauss-Bonnet theory
The classification of certain class of static solutions for the
Einstein-Gauss-Bonnet theory in vacuum is presented. The spacelike section of
the class of metrics under consideration is a warped product of the real line
with a nontrivial base manifold. For arbitrary values of the Gauss-Bonnet
coupling, the base manifold must be Einstein with an additional scalar
restriction. The geometry of the boundary can be relaxed only when the
Gauss-Bonnet coupling is related with the cosmological and Newton constants, so
that the theory admits a unique maximally symmetric solution. This additional
freedom in the boundary metric allows the existence of three main branches of
geometries in the bulk, containing new black holes and wormholes in vacuum.Comment: Prepared for the proceedings of the 7th Alexander Friedmann
International Seminar on Gravitation and Cosmology, July 2008, Joao Pessoa,
Brasil. 4 pages, References adde
Analytical infrared intensities for periodic systems with local basis sets
We report a method for the efficient evaluation of analytic infrared (IR)
intensities within generalized Kohn-Sham density functional theory using
Gaussian orbitals and periodic boundary conditions. A discretized form of the
Berry phase is used to evaluate a periodic dipole moment and its derivatives
with respect to in-phase nuclear coordinate displacements. Benchmark
calculations are presented for one-dimensional chains of water molecules and
poly(paraphenylenevinylene).Comment: 16 pages, 3 figures, 4 tables, submitted to Phys. Rev.
What makes representative constructivism democratic?
This article connects J. S. Mill’s democratic theory and practice with the contemporary debate surrounding representative constructivism and argues that Mill’s advocacy of female suffrage affords an empirical example of the mobilization power of representative constructivism. Studying this concrete example of constructivism alongside Mill’s theory of political representation clarifies that constructivism is democratic to the extent it seeks to make citizens themselves appropriate and contest the claims that their representatives construct on their behalf
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