3,530 research outputs found
Dynamic Influence Networks for Rule-based Models
We introduce the Dynamic Influence Network (DIN), a novel visual analytics
technique for representing and analyzing rule-based models of protein-protein
interaction networks. Rule-based modeling has proved instrumental in developing
biological models that are concise, comprehensible, easily extensible, and that
mitigate the combinatorial complexity of multi-state and multi-component
biological molecules. Our technique visualizes the dynamics of these rules as
they evolve over time. Using the data produced by KaSim, an open source
stochastic simulator of rule-based models written in the Kappa language, DINs
provide a node-link diagram that represents the influence that each rule has on
the other rules. That is, rather than representing individual biological
components or types, we instead represent the rules about them (as nodes) and
the current influence of these rules (as links). Using our interactive DIN-Viz
software tool, researchers are able to query this dynamic network to find
meaningful patterns about biological processes, and to identify salient aspects
of complex rule-based models. To evaluate the effectiveness of our approach, we
investigate a simulation of a circadian clock model that illustrates the
oscillatory behavior of the KaiC protein phosphorylation cycle.Comment: Accepted to TVCG, in pres
A Search for Dense Molecular Gas in High Redshift Infrared-Luminous Galaxies
We present a search for HCN emission from four high redshift far infrared
(IR) luminous galaxies. Current data and models suggest that these high IR
luminous galaxies represent a major starburst phase in the formation of
spheroidal galaxies, although many of the sources also host luminous active
galactic nuclei (AGN), such that a contribution to the dust heating by the AGN
cannot be precluded. HCN emission is a star formation indicator, tracing dense
molecular hydrogen gas within star-forming molecular clouds (n(H) cm). HCN luminosity is linearly correlated with IR luminosity for
low redshift galaxies, unlike CO emission which can also trace gas at much
lower density. We report a marginal detection of HCN (1-0) emission from the
QSO J1409+5628, with a velocity integrated line luminosity of
K km s pc, while we obtain
3 upper limits to the HCN luminosity of the QSO J0751+2716 of
K km s pc, K km s pc for the starburst galaxy
J1401+0252, and K km s pc for the QSO J1148+5251. We compare the HCN data on these sources, plus three
other high- IR luminous galaxies, to observations of lower redshift
star-forming galaxies. The values of the HCN/far-IR luminosity ratios (or
limits) for all the high sources are within the scatter of the relationship
between HCN and far-IR emission for low star-forming galaxies (truncated).Comment: aastex format, 4 figures. to appear in the Astrophysical Journal;
Revised lens magnification estimate for 1401+025
RuleVis: Constructing Patterns and Rules for Rule-Based Models
We introduce RuleVis, a web-based application for defining and editing
"correct-by-construction" executable rules that model biochemical
functionality, which can be used to simulate the behavior of protein-protein
interaction networks and other complex systems. Rule-based models involve
emergent effects based on the interactions between rules, which can vary
considerably with regard to the scale of a model, requiring the user to inspect
and edit individual rules. RuleVis bridges the graph rewriting and systems
biology research communities by providing an external visual representation of
salient patterns that experts can use to determine the appropriate level of
detail for a particular modeling context. We describe the visualization and
interaction features available in RuleVisand provide a detailed example
demonstrating how RuleVis can be used to reason about intracellular
interactions
Mitochondrial phylogenomics of the Bivalvia (Mollusca): searching for the origin and mitogenomic correlates of doubly uniparental inheritance of mtDNA
<p>Abstract</p> <p>Background</p> <p>Doubly uniparental inheritance (DUI) is an atypical system of animal mtDNA inheritance found only in some bivalves. Under DUI, maternally (F genome) and paternally (M genome) transmitted mtDNAs yield two distinct gender-associated mtDNA lineages. The oldest distinct M and F genomes are found in freshwater mussels (order Unionoida). Comparative analyses of unionoid mitochondrial genomes and a robust phylogenetic framework are necessary to elucidate the origin, function and molecular evolutionary consequences of DUI. Herein, F and M genomes from three unionoid species, <it>Venustaconcha ellipsiformis, Pyganodon grandis </it>and <it>Quadrula quadrula </it>have been sequenced. Comparative genomic analyses were carried out on these six genomes along with two F and one M unionoid genomes from GenBank (F and M genomes of <it>Inversidens japanensis </it>and F genome of <it>Lampsilis ornata</it>).</p> <p>Results</p> <p>Compared to their unionoid F counterparts, the M genomes contain some unique features including a novel localization of the <it>trnH </it>gene, an inversion of the <it>atp8-trnD </it>genes and a unique 3'coding extension of the cytochrome <it>c </it>oxidase subunit II gene. One or more of these unique M genome features could be causally associated with paternal transmission. Unionoid bivalves are characterized by extreme intraspecific sequence divergences between gender-associated mtDNAs with an average of 50% for <it>V. ellipsiformis</it>, 50% for <it>I. japanensis</it>, 51% for <it>P. grandis </it>and 52% for <it>Q. quadrula </it>(uncorrected amino acid p-distances). Phylogenetic analyses of 12 protein-coding genes from 29 bivalve and five outgroup mt genomes robustly indicate bivalve monophyly and the following branching order within the autolamellibranch bivalves: ((Pteriomorphia, Veneroida) Unionoida).</p> <p>Conclusion</p> <p>The basal nature of the Unionoida within the autolamellibranch bivalves and the previously hypothesized single origin of DUI suggest that (1) DUI arose in the ancestral autolamellibranch bivalve lineage and was subsequently lost in multiple descendant lineages and (2) the mitochondrial genome characteristics observed in unionoid bivalves could more closely resemble the DUI ancestral condition. Descriptions and comparisons presented in this paper are fundamental to a more complete understanding regarding the origins and consequences of DUI.</p
Radio continuum imaging of FIR luminous QSOs at z>6
We present sensitive imaging at 1.4 GHz of the two highest redshift
far-infrared (FIR) luminous QSOs SDSS J114816.65+525150.2 (z=6.42) and SDSS
J104845.05+463718.3 (z=6.2). Radio continuum emission is detected from
J1148+5251 with S_{1.4} = 55 \pm 12 uJy, while J1048+4637 is marginally
detected with S_{1.4} = 26 \pm 12 uJy. Comparison of the radio and FIR
luminosities shows that both sources follow the radio-FIR correlation for star
forming galaxies, with implied (massive) star formation rates \sim 10^3 M_sun
year^{-1}, although we cannot rule-out as much as 50% of the FIR luminosity
being powered by the AGN. Five bright (> 22 mJy) radio sources are detected
within 8' of J1148+5251. This is a factor 30 more than expected for a random
field. Two sources have SDSS redshifts, including a z = 1.633 radio loud quasar
and a z = 0.05 radio galaxy. However, we do not find evidence for a galaxy
cluster in the SDSS data, at least out to z = 0.2. Considering the faint SDSS
magnitudes of the remaining radio sources, we conclude that the over-density of
radio sources could either be a statistical fluke, or a very large scale
structure (> 8 Mpc comoving) at z > 1. We also consider the possibility of
gravitational lensing by the closest (in angle) bright galaxy in the SDSS data
at z = 0.05, and conclude that the galaxy provides negligible magnification.Comment: aastex, 5 figures, 2 tables. to appear in the Astronomical Journa
A massive proto-cluster of galaxies at a redshift of z {\approx} 5.3
Massive clusters of galaxies have been found as early as 3.9 Billion years
(z=1.62) after the Big Bang containing stars that formed at even earlier
epochs. Cosmological simulations using the current cold dark matter paradigm
predict these systems should descend from "proto-clusters" - early
over-densities of massive galaxies that merge hierarchically to form a cluster.
These proto-cluster regions themselves are built-up hierarchically and so are
expected to contain extremely massive galaxies which can be observed as
luminous quasars and starbursts. However, observational evidence for this
scenario is sparse due to the fact that high-redshift proto-clusters are rare
and difficult to observe. Here we report a proto-cluster region 1 billion years
(z=5.3) after the Big Bang. This cluster of massive galaxies extends over >13
Mega-parsecs, contains a luminous quasar as well as a system rich in molecular
gas. These massive galaxies place a lower limit of >4x10^11 solar masses of
dark and luminous matter in this region consistent with that expected from
cosmological simulations for the earliest galaxy clusters.Comment: Accepted to Nature, 16 Pages, 6 figure
Intraoperative ketorolac in high-risk breast cancer patients : A prospective, randomized, placebo-controlled clinical trial
Funding: This work is financed by grants received by PF, in the name of his institution: the Anticancer Fund (no grant number) (www.anticancerfund.org); the Belgian Society of Anaesthesia and Resuscitation (no grant number) (www.sarb.be); the Fondation Saint-Luc (no grant number) (www.uclouvain.be); the Commission du Patrimoine of the Université catholique de Louvain, St-Luc Hospital (exceptional grant, no number) (www.uclouvain.be). None of the funders had any role in the study design, data collection and analysis, decision to publish or preparation of the manuscript except the scientific advise of GB, scientific director of the Anticancer Fund.Peer reviewedPublisher PD
Finite-Temperature Transport in Finite-Size Hubbard Rings in the Strong-Coupling Limit
We study the current, the curvature of levels, and the finite temperature
charge stiffness, D(T,L), in the strongly correlated limit, U>>t, for Hubbard
rings of L sites, with U the on-site Coulomb repulsion and t the hopping
integral. Our study is done for finite-size systems and any band filling. Up to
order t we derive our results following two independent approaches, namely,
using the solution provided by the Bethe ansatz and the solution provided by an
algebraic method, where the electronic operators are represented in a
slave-fermion picture. We find that, in the U=\infty case, the
finite-temperature charge stiffness is finite for electronic densities, n,
smaller than one. These results are essencially those of spinless fermions in a
lattice of size L, apart from small corrections coming from a statistical flux,
due to the spin degrees of freedom. Up to order t, the Mott-Hubbard gap is
\Delta_{MH}=U-4t, and we find that D(T) is finite for n<1, but is zero at
half-filling. This result comes from the effective flux felt by the holon
excitations, which, due to the presence of doubly occupied sites, is
renormalized to
\Phi^{eff}=\phi(N_h-N_d)/(N_d+N_h), and which is zero at half-filling, with
N_d and N_h being the number of doubly occupied and empty lattice sites,
respectively. Further, for half-filling, the current transported by any
eigenstate of the system is zero and, therefore, D(T) is also zero.Comment: 15 pages and 6 figures; accepted for PR
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