5,062 research outputs found
A first step towards computing all hybridization networks for two rooted binary phylogenetic trees
Recently, considerable effort has been put into developing fast algorithms to
reconstruct a rooted phylogenetic network that explains two rooted phylogenetic
trees and has a minimum number of hybridization vertices. With the standard
approach to tackle this problem being combinatorial, the reconstructed network
is rarely unique. From a biological point of view, it is therefore of
importance to not only compute one network, but all possible networks. In this
paper, we make a first step towards approaching this goal by presenting the
first algorithm---called allMAAFs---that calculates all
maximum-acyclic-agreement forests for two rooted binary phylogenetic trees on
the same set of taxa.Comment: 21 pages, 5 figure
OddzOn Products and Derivation of Invention: At Odds with the Purpose of Section 102(f) of the Patent Act of 1952?
Abstract Background Antimicrobial peptides are important components of the host defence with a broad range of functions including direct antimicrobial activity and modulation of inflammation. Lack of cathelin-related antimicrobial peptide (CRAMP) was associated with higher mortality and bacterial burden and impaired neutrophil granulocyte infiltration in a model of pneumococcal meningitis. The present study was designed to characterize the effects of CRAMP deficiency on glial response and phagocytosis after exposure to bacterial stimuli. Methods CRAMP-knock out and wildtype glial cells were exposed to bacterial supernatants from Streptococcus pneumoniae and Neisseria meningitides or the bacterial cell wall components lipopolysaccharide and peptidoglycan. Cell viability, expression of pro- and anti-inflammatory mediators and activation of signal transduction pathways, phagocytosis rate and glial cell phenotype were investigated by means of cell viability assays, immunohistochemistry, real-time RT-PCR and Western blot. Results CRAMP-deficiency was associated with stronger expression of pro-inflammatory and weakened expression of anti-inflammatory cytokines indicating a higher degree of glial cell activation even under resting-state conditions. Furthermore, increased translocation of nuclear factor ‘kappa-light-chain-enhancer’ of activated B-cells was observed and phagocytosis of S. pneumoniae was reduced in CRAMP-deficient microglia indicating impaired antimicrobial activity. Conclusions In conclusion, the present study detected severe alterations of the glial immune response due to lack of CRAMP. The results indicate the importance of CRAMP to maintain and regulate the delicate balance between beneficial and harmful immune response in the brain
A statistical equilibrium model of competitive firms
We find that the empirical density of firm profit rates, measured as returns on assets, is markedly non-Gaussian and reasonably well described by an exponential power (or Subbotin) distribution. We start from a statistical equilibrium model that leads to a stationary Subbotin density in the presence of complex interactions among competitive heterogeneous firms. To investigate the dynamics of firm profitability, we construct a diffusion process that has the Subbotin distribution as its stationary probability density. This leads to a phenomenologically inspired interpretation of variations in the shape parameter of the Subbotin distribution, which essentially measures the competitive pressure in and across industries. Our findings have profound implications both for the previous literature on the ‘persistence of profits’ as well as for understanding competition as a dynamic process. Our main formal finding is that firms' idiosyncratic efforts and the tendency for competition to equalize profit rates are two sides of the same coin, and that a ratio of these two effects ultimately determines the dispersion of the equilibrium distribution
Supersymmetric Inflation with the Ordinary Higgs?
We consider a model of D-term inflation in which the inflaton coincides with
the standard Higgs doublet. Non-renormalizable terms are controlled by a
discrete R-symmetry of the superpotential. We consider radiative corrections to
the scalar potential and find that Higgs inflation in the slow-roll
approximation is viable and consistent with CMB data, although with a rather
large value of the non-renormalizable coupling involved.Comment: 7 pages, 1 figure, published version, comments and reference added,
typos and factor of 2 corrected
Photoassociation and coherent transient dynamics in the interaction of ultracold rubidium atoms with shaped femtosecond pulses - I. Experiment
We experimentally investigate various processes present in the
photoassociative interaction of an ultracold atomic sample with shaped
femtosecond laser pulses. We demonstrate the photoassociation of pairs of
rubidium atoms into electronically excited, bound molecular states using
spectrally cut femtosecond laser pulses tuned below the rubidium D1 or D2
asymptote. Time-resolved pump-probe spectra reveal coherent oscillations of the
molecular formation rate, which are due to coherent transient dynamics in the
electronic excitation. The oscillation frequency corresponds to the detun-ing
of the spectral cut position to the asymptotic transition frequency of the
rubidium D1 or D2 lines, respectively. Measurements of the molecular
photoassociation signal as a function of the pulse energy reveal a non-linear
dependence and indicate a non-perturbative excitation process. Chirping the
association laser pulse allowed us to change the phase of the coherent
transients. Furthermore, a signature for molecules in the electronic ground
state is found, which is attributed to molecule formation by femtosecond
photoassociation followed by spontaneous decay. In a subsequent article [A.
Merli et al., submitted] quantum mechanical calculations are presented, which
compare well with the experimental data and reveal further details about the
observed coherent transient dynamics
Semileptonic Decays: an Update Down Under
Heavy-meson semileptonic decays calculations on the lattice are reviewed. The
focus is upon obtaining reliable matrix elements. Errors that depend upon the
lattice spacing, , are an important source of systematic error. Full
improvement of matrix elements for arbitrary-mass four-component quarks is
discussed. With improvement, bottom-quark matrix elements can be calculated
directly using current lattices. Momentum dependent errors for -improved
quarks and statistical noise limit momenta to around 1 GeV/c with current
lattices. Hence, maximum recoil momenta can be reached for decays while
only a fraction of the maximum recoil momentum can be reliably studied for the
light-meson decay modes of the . Differential decay rates and partial widths
are phenomenologically important quantities in decays that can be reliably
determined with present lattices.Comment: 14 pages, 9 postscript figures, requires espcrc2.st
Boltzmann brains and the scale-factor cutoff measure of the multiverse
To make predictions for an eternally inflating "multiverse", one must adopt a
procedure for regulating its divergent spacetime volume. Recently, a new test
of such spacetime measures has emerged: normal observers - who evolve in pocket
universes cooling from hot big bang conditions - must not be vastly outnumbered
by "Boltzmann brains" - freak observers that pop in and out of existence as a
result of rare quantum fluctuations. If the Boltzmann brains prevail, then a
randomly chosen observer would be overwhelmingly likely to be surrounded by an
empty world, where all but vacuum energy has redshifted away, rather than the
rich structure that we observe. Using the scale-factor cutoff measure, we
calculate the ratio of Boltzmann brains to normal observers. We find the ratio
to be finite, and give an expression for it in terms of Boltzmann brain
nucleation rates and vacuum decay rates. We discuss the conditions that these
rates must obey for the ratio to be acceptable, and we discuss estimates of the
rates under a variety of assumptions.Comment: 32 pp, 2 figs. Modified to conform to the version accepted by Phys.
Rev. D. The last paragraph of Sec. V-A, about Boltzmann brains in Minkowski
space, has been significantly enlarged. Two sentences were added to the
introduction concerning the classical approximation and the hope of finding a
motivating principle for the measure. Several references were adde
MIDGARD: A Simulation Platform for Autonomous Navigation in Unstructured Environments
We present MIDGARD, an open-source simulation platform for autonomous robot
navigation in outdoor unstructured environments. MIDGARD is designed to enable
the training of autonomous agents (e.g., unmanned ground vehicles) in
photorealistic 3D environments, and to support the generalization skills of
learning-based agents through the variability in training scenarios. MIDGARD's
main features include a configurable, extensible, and difficulty-driven
procedural landscape generation pipeline, with fast and photorealistic scene
rendering based on Unreal Engine. Additionally, MIDGARD has built-in support
for OpenAI Gym, a programming interface for feature extension (e.g.,
integrating new types of sensors, customizing exposing internal simulation
variables), and a variety of simulated agent sensors (e.g., RGB, depth and
instance/semantic segmentation). We evaluate MIDGARD's capabilities as a
benchmarking tool for robot navigation utilizing a set of state-of-the-art
reinforcement learning algorithms. The results demonstrate MIDGARD's
suitability as a simulation and training environment, as well as the
effectiveness of our procedural generation approach in controlling scene
difficulty, which directly reflects on accuracy metrics. MIDGARD build, source
code and documentation are available at https://midgardsim.org/
Holographic Multiverse
We explore the idea that the dynamics of the inflationary multiverse is
encoded in its future boundary, where it is described by a lower dimensional
theory which is conformally invariant in the UV. We propose that a measure for
the multiverse, which is needed in order to extract quantitative probabilistic
predictions, can be derived in terms of the boundary theory by imposing a UV
cutoff. In the inflationary bulk, this is closely related (though not
identical) to the so-called scale factor cutoff measure.Comment: 23 pages, 4 figures. Replaced to match published versio
Desempenho zootécnico e condenação ao abate de frangos criados em aviários dark house e convencional / Zootechnical performance and slaughter condemnation of chickens raised in dark house and conventional houses
Nos últimos anos a avicultura de corte brasileira vem ganhando significativo espaço no setor produtivo mundial e, para acompanhar esse desenvolvimento, técnicas de manejo que visam maximizar a produção são procuradas pelas empresas produtoras. Objetivou-se comparar o desempenho zootécnico e as condenações de carcaça de frangos produzidos em aviários Dark House e convencionais. Para isso, foram selecionadas as fichas de controle produtivo dos frangos de linhagem Cobb abatidos no ano de 2020, no municÃpio de Medianeira, PR. Foram ao todo 32 lotes provenientes de 8 aviários, sendo 4 do sistema Dark House e 4 do sistema Convencional. Foram calculadas as médias e posteriormente realizado a análise estatÃstica dos dados pelo software Statistical Package for the Social Sciences (SPSS), version 23.0 (2020), considerando significante p<0,05. Em relação ao desempenho zootécnico, foi observado diferença significativa (p=0,016) na média de ganho de peso diário entre os frangos dark house (72,19 g ± 2,76) e convencional (69,00 g ± 3,81). Os valores de conversão alimentar e peso médio não diferiram entre os tratamentos (p>0,005). Tratando-se das condenações ao abate, os frangos do Dark House apresentaram menor porcentagem de calo nos pés (1,20 ± 2,49) do que o convencional (5,71 ± 6,12) (p=0,006). Os outros parâmetros avaliados não demonstraram diferença estatÃstica entre os dois tipos de aviários. Os aviários Dark House demonstram trazer benefÃcios a produção, entretanto, para alcançar o seu potencial, é necessário atenção ao manejo com as aves, desde a criação até o abate, objetivando a melhor eficiência produtiva
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