12,307 research outputs found
Clone size distributions in networks of genetic similarity
We build networks of genetic similarity in which the nodes are organisms
sampled from biological populations. The procedure is illustrated by
constructing networks from genetic data of a marine clonal plant. An important
feature in the networks is the presence of clone subgraphs, i.e. sets of
organisms with identical genotype forming clones. As a first step to understand
the dynamics that has shaped these networks, we point up a relationship between
a particular degree distribution and the clone size distribution in the
populations. We construct a dynamical model for the population dynamics,
focussing on the dynamics of the clones, and solve it for the required
distributions. Scale free and exponentially decaying forms are obtained
depending on parameter values, the first type being obtained when clonal growth
is the dominant process. Average distributions are dominated by the power law
behavior presented by the fastest replicating populations.Comment: 17 pages, 4 figures. One figure improved and other minor changes. To
appear in Physica
MODELING AND OPTMIZATION POWER REQUIREMENTS OF ACTIVE ACOUSTIC LOUVRES
The development of new technologies for ventilated facades is within the context of energy efficiency of buildings , including the compatibility of the dichotomy between natural ventilation and soundproofing in tropical countries . Given this perspective, this work proposes the application of techniques for active noise control in acoustic louvers . One limitation of the spread of technical active noise control in buildings is the energy inherent in the technique. Thus, the proposed system is based on the reduction of structural vibrations of the shutter blades by using piezoelectric actuators . The acoustic transmission loss and energy requirements for active shutters are investigated from numerical modeling . The results suggest their technical feasibility with superior soundproofing to 30 dB and power consumption less than 35 W. Thus , the active noise control using piezoelectric actuators is presented as a promising technology , aligning soundproofing with low energy consumption Type the text of the abstract here, Times New Roman, 9, lower case letters, justified paragraphs, 1.0 line spacing. The abstract should state the objectives, methodology and main conclusions in 200 to 300 words. No not divide into paragraphs
Effect of the carbon source in the regulation of flocculation of Ale Brewer yeast strains
Instituto Politécnico do Porto. Fundo de Apoio à Investigação, Programa Plurianual de Unidades de I&D - CIEA/ISEP
Evolutionary and Ecological Trees and Networks
Evolutionary relationships between species are usually represented in
phylogenies, i.e. evolutionary trees, which are a type of networks. The
terminal nodes of these trees represent species, which are made of individuals
and populations among which gene flow occurs. This flow can also be represented
as a network. In this paper we briefly show some properties of these complex
networks of evolutionary and ecological relationships. First, we characterize
large scale evolutionary relationships in the Tree of Life by a degree
distribution. Second, we represent genetic relationships between individuals of
a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum
Spanning Tree. Finally, relationships among plant shoots inside populations are
represented as networks of genetic similarity.Comment: 6 pages, 5 figures. To appear in Proceedings of the Medyfinol06
Conferenc
Preparation of acetazolamide composite microparticles by supercritical antisolvent techniques
The possibility of preparation of ophthalmic drug delivery systems using compressed anti-solvent technology was evaluated. and RL 100 were used as drug carriers, acetazolamide was the model drug processed. Compressed anti-solvent experiments were carried out as
a semi-continuous or a batch operation from a liquid solution of polymer(s) + solute dissolved in acetone. Both techniques allowed the recovery
of composite particles, but the semi-continuous operation yielded smaller and less aggregated populations than the batch operation. The release
behaviour of acetazolamide from the prepared microparticles was studied and most products exhibited a slower release than the single drug.
Moreover, the release could be controlled to some extent by varying the ratio of the two Eudragit used in the formulation and by selecting one
or the other anti-solvent technique. Simple diffusion models satisfactorily described the release profiles. Composites specifically produced by
semi-continuous technique have a drug release rate controlled by a diffusion mechanism, whereas for composites produced by the batch operation,
the polymer swelling also contributes to the overall transport mechanism
On stochastic sea of the standard map
Consider a generic one-parameter unfolding of a homoclinic tangency of an
area preserving surface diffeomorphism. We show that for many parameters
(residual subset in an open set approaching the critical value) the
corresponding diffeomorphism has a transitive invariant set of full
Hausdorff dimension. The set is a topological limit of hyperbolic sets
and is accumulated by elliptic islands.
As an application we prove that stochastic sea of the standard map has full
Hausdorff dimension for sufficiently large topologically generic parameters.Comment: 36 pages, 5 figure
The galaxy environment in GAMA G3C groups using the Kilo Degree Survey Data Release 3
We aim to investigate the galaxy environment in GAMA Galaxy Groups Catalogue
(G3C) using a volume-limited galaxy sample from the Kilo Degree Survey Data
Release 3. The k-Nearest Neighbour technique is adapted to take into account
the probability density functions (PDFs) of photometric redshifts in our
calculations. This algorithm was tested on simulated KiDS tiles, showing its
capability of recovering the relation between galaxy colour, luminosity and
local environment. The characterization of the galaxy environment in G3C groups
shows systematically steeper density contrasts for more massive groups. The red
galaxy fraction gradients in these groups is evident for most of group mass
bins. The density contrast of red galaxies is systematically higher at group
centers when compared to blue galaxy ones. In addition, distinct group center
definitions are used to show that our results are insensitive to center
definitions. These results confirm the galaxy evolution scenario which
environmental mechanisms are responsible for a slow quenching process as
galaxies fall into groups and clusters, resulting in a smooth observed colour
gradients in galaxy systems.Comment: 14 pages, Accepted to MNRA
Genome sequence of Rhizobium sullae HCNT1 isolated from Hedysarum coronarium nodules and featuring peculiar denitrification phenotypes
The genome sequence of Rhizobium sullae strain HCNT1, isolated from root nodules of the legume Hedysarum coronarium growing in wild stands in Tuscany, Italy, is described here. Unlike other R. sullae strains, this isolate features a truncated denitrification pathway lacking NO/N2O reductase activity and displaying high sensitivity to nitrite under anaerobic conditions
All-sky angular power spectra from cleaned WISESuperCOSMOS galaxy number counts
Aiming to extract cosmological information from linear scales of the
WISESuperCOSMOS photometric redshift catalog, we perform a
characterization of the systematic effects associated with stellar content,
evidencing the presence of contamination and obscuration. We create an
integrated model for these effects (which together we call `usurper
contamination'), devise a method to remove both of them simultaneously and show
its functionality by applying it to a set of mock catalogs. When administered
to WISESuperCOSMOS data, our method shows to improve the measurements
of angular power spectra on scales and the extraction of
cosmological parameters therefrom, even though a significant excess of power
remains at these scales. When ignoring scales , we still find strong
indications of systematics, albeit these can be localized in the southern
equatorial hemisphere. An independent analysis of the northern hemisphere at
agrees with a CDM model with parameters from the Planck
satellite and gives and
at 95% confidence limit when combined with priors
on , and .Comment: 33 pages, 20 figures, 5 tables. Accepted for publication in JCA
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