3,903 research outputs found
A remark on approximation with polynomials and greedy bases
We investigate properties of the -th error of approximation by polynomials
with constant coefficients and with modulus-constant
coefficients introduced by Bern\'a and Blasco
(2016) to study greedy bases in Banach spaces. We characterize when
and are
equivalent to in terms of the democracy and superdemocracy functions,
and provide sufficient conditions ensuring that , extending previous very particular
results
Tree-structure Expectation Propagation for Decoding LDPC codes over Binary Erasure Channels
Expectation Propagation is a generalization to Belief Propagation (BP) in two
ways. First, it can be used with any exponential family distribution over the
cliques in the graph. Second, it can impose additional constraints on the
marginal distributions. We use this second property to impose pair-wise
marginal distribution constraints in some check nodes of the LDPC Tanner graph.
These additional constraints allow decoding the received codeword when the BP
decoder gets stuck. In this paper, we first present the new decoding algorithm,
whose complexity is identical to the BP decoder, and we then prove that it is
able to decode codewords with a larger fraction of erasures, as the block size
tends to infinity. The proposed algorithm can be also understood as a
simplification of the Maxwell decoder, but without its computational
complexity. We also illustrate that the new algorithm outperforms the BP
decoder for finite block-siz
A bibliometric study of the research area of videogames using Dimensions.ai database
Videogames are a very interesting area of research for fields as diverse as computer science, health, psychology or even social sciences. Every year a growing number of articles are published in different topics inside this field, so it is very convenient to study the different bibliometric data in order to consolidate the research efforts.
Thus, the aim of this work is to conduct a study on the distribution of articles related to videogames in the different fields of research, as well as to measure their interest over time, to identify the sources, countries and authors with the highest scientific production. In order to carry out this analysis, the information system Dimensions.ai has been considered, since it covers a large number of documents and allows for easy downloading and analysis of datasets.
According to the study, three countries are the most prolific in this area: USA, Canada and UK. The obtained results also indicate that the fields with the highest number of publications are Information and Computer Sciences, Medical and Health Sciences, and Psychology and Cognitive Sciences, in this order. With regard to the impact of the publications, differences between the number of citations, and the number of Altmetric Attention Score, have been found
Formation of S0 galaxies through mergers. Bulge-disc structural coupling resulting from major mergers
Observations reveal a strong structural coupling between bulge and disc in S0
galaxies, which seems difficult to explain if they have formed from supposedly
catastrophic events such as major mergers. We face this question by quantifying
the bulge-disc coupling in dissipative simulations of major and minor mergers
that result in realistic S0s. We have studied the dissipative N-body binary
merger simulations from the GalMer database that give rise to realistic,
relaxed E/S0 and S0 remnants (67 major and 29 minor mergers). We simulate
surface brightness profiles of these S0-like remnants in the K-band, mimicking
typical observational conditions, to perform bulge-disc decompositions
analogous to those carried out in real S0s. The global bulge-disc structure of
these remnants has been compared with real data, and they distribute in the B/T
- r_e - h_d parameter space consistently with real bright S0s, where B/T is the
bulge-to-total luminosity ratio, r_e is the bulge effective radius, and h_d is
the disc scalelength. Major mergers can rebuild a bulge-disc coupling in the
remnants after having destroyed the structures of the progenitors, whereas
minor mergers directly preserve them. Remnants exhibit B/T and r_e/h_d spanning
a wide range of values, and their distribution is consistent with observations.
Many remnants have bulge Sersic indices ranging 1<n<2, flat appearance, and
contain residual star formation in embedded discs, a result which agrees with
the presence of pseudobulges in real S0s. Contrary to the popular view, mergers
(and in particular, major events) can result in S0 remnants with realistically
coupled bulge-disc structures in less than ~3 Gyr. In conclusion, the
bulge-disc coupling and the presence of pseudobulges in real S0s cannot be used
as an argument against the possible major-merger origin of these galaxies.Comment: 23 pages, accepted for publication in Astronomy and Astrophysics
(version after minor language corrections
Comparative Analysis of the Type III Secretion System Effector Repertoires of Pseudomonas savastanoi Pathovars Pathogenic on Woody Hosts
Comunicación de tipo pósterThe species Pseudomonas savastanoi, a member of the Pseudomonas syringae complex,
includes four pathovars causing knots or excrescences in woody hosts: P. savastanoi pv.
savastanoi (Psv), pv. fraxini (Psf), pv. nerii (Psn) and pv. retacarpa (Psr), comprising isolates
from olive, ash, oleander and broom plants, respectively. Pathogenicity of P. savastanoi is
dependent, among other factors, on the type III secretion system (T3SS) and its effector
(T3E) repertoire. Furthermore, a putative role in the interaction with woody hosts has been
suggested for several of these T3E. The recent availability of the genome sequences of
several P. savastanoi strains isolated from different hosts has facilitated bioinformatics
predictions of their T3SS genes and T3E pools, the study of their distribution in other strains
of the P. syringae complex isolated from woody hosts and the functional analysis of several
of these secreted proteins. As previously reported for Psv, Psn and Psf, here we show that
pathogenicity of Psr ICMP16945, is also dependent on the T3SS. Psv strains NCPPB 3335,
ICMP4352 and PseNe107 share a core set of at least 22 T3E, 18 of which are also encoded in
Psn ICMP16943, Psf ICMP7711 and Psr ICMP16945. However, these three strains encode
truncated versions of 1-2 of these 18 T3E and, Psr ICMP16945 contains three pathovarspecific
T3E. Our results also show that several T3E, including HopAO1, are phylogenetically
clustered across the P. syringae complex according to the woody/herbaceous nature of their
host of isolation, suggesting host specialization of these effectors in this complex.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
-covering red and blue points in the plane
We say that a finite set of red and blue points in the plane in general
position can be -covered if the set can be partitioned into subsets of
size , with points of one color and point of the other color, in
such a way that, if at each subset the fourth point is connected by
straight-line segments to the same-colored points, then the resulting set of
all segments has no crossings. We consider the following problem: Given a set
of red points and a set of blue points in the plane in general
position, how many points of can be -covered? and we prove
the following results:
(1) If and , for some non-negative integers and ,
then there are point sets , like -equitable sets (i.e.,
or ) and linearly separable sets, that can be -covered.
(2) If , and the points in are in convex position,
then at least points can be -covered, and this bound is tight.
(3) There are arbitrarily large point sets in general position,
with , such that at most points can be -covered.
(4) If , then at least points of
can be -covered. For , there are too many red points and at
least of them will remain uncovered in any -covering.
Furthermore, in all the cases we provide efficient algorithms to compute the
corresponding coverings.Comment: 29 pages, 10 figures, 1 tabl
A local fingerprint for hydrophobicity and hydrophilicity: from methane to peptides
An important characteristic that determines the behavior of a solute in water
is whether it is hydrophobic or hydrophilic. The traditional classification is
based on chemical experience and heuristics. However, this does not reveal how
the local environment modulates this important property. We present a local
fingerprint for hydrophobicity and hydrophilicity inspired by the two body
contribution to the entropy. This fingerprint is an inexpensive, quantitative
and physically meaningful way of studying hydrophilicity and hydrophobicity
that only requires as input the water-solute radial distribution functions. We
apply our fingerprint to octanol, benzene and the 20 proteinogenic amino acids.
Our measure of hydrophilicity is coherent with chemical experience and,
moreover, it also shows how the character of an atom can change as its
environment is changed. Lastly, we use the fingerprint as collective variable
in a funnel metadynamics simulation of a host-guest system. The fingerprint
serves as a desolvation collective variable that enhances transitions between
the bound and unbound states
- …