2,301 research outputs found
Adaptive soundscape design for liveable urban spaces: a hybrid methodology across environmental acoustics and sonic art
The aim of this research is to identify and implement soundscape improvement strategies in urban areas based on loudspeaker placements in the outdoor environment and the use of a computer-based system for adaptive soundscape generation, integrating sonic art practice with acoustic engineering rigour
Lista atualizada de quirópteros da Amazônia Brasileira
We present an updated checklist on bats of the Amazon Basin in Brazil, based on our collection of 3.081 specimens in 12 areas in the Basin and a review of the existing literature. The list consists of 95 species belonging to 51 genera and 9 families: 3 species (Micronycteris hirsuta, Natalus stramineus and Rhogessa tumida) are being cited for the first time as present in the Amazon Basin; of the remaining 92 species reported by previous workers. 68 were registered and confirmed by the present authors.É apresentada uma lista atualizada de quirópteros da região amazônica brasileira, baseada em nossa coleção de 3.081 exemplares capturados em 12 áreas na Bacia Amazônica e com referência às literaturas anteriormente publicadas. A lista conta com 95 espécies de 51 gêneros e 9 famílias, sendo 3 espécies (Micronycteris hirsuta, Natalus stramineus e Rhogessa tumida) citadas pela primeira vez como ocorrendo na região; e das demais alistadas por pesquisadores anteriores, são registradas e confirmadas 68 espécies
Sharp weighted estimates for classical operators
We give a new proof of the sharp one weight inequality for any operator
that can be approximated by Haar shift operators such as the Hilbert
transform, any Riesz transform, the Beurling-Ahlfors operator. Our proof avoids
the Bellman function technique and two weight norm inequalities. We use instead
a recent result due to A. Lerner to estimate the oscillation of dyadic
operators. Our method is flexible enough to prove the corresponding sharp
one-weight norm inequalities for some operators of harmonic analysis: the
maximal singular integrals associated to , Dyadic square functions and
paraproducts, and the vector-valued maximal operator of C. Fefferman-Stein.
Also we can derive a very sharp two-weight bump type condition for .Comment: We improve different parts of the first version, in particular we
show the sharpness of our theorem for the vector-valued maximal functio
The signature of dark energy on the local Hubble flow
Using N-body simulations of flat, dark energy dominated cosmologies, we show
that galaxies around simulated binary systems resembling the Local Group (LG)
have low peculiar velocities, in good agreement with observational data. We
have compared results for LG-like systems selected from large, high resolution
simulations of three cosmologies: a LCDM model, a LWDM model with a 2 keV warm
dark matter candidate and a quintessence model (QCDM) with an equation of state
parameter w=-0.6.
The Hubble flow is significant colder around LGs selected in a flat, Lambda
dominated cosmology than around LGs in open or critical models, showing that a
dark energy component manifests itself on the scales of nearby galaxies,
cooling galaxy peculiar motions. Flows in the LWDM and QCDM models are
marginally colder than in the LCDM one.
The results of our simulations have been compared to existing data and a new
data set of 28 nearby galaxies with robust distance measures (Cepheids and
Surface Brightness Fluctuations). The measured line-of-sight velocity
dispersion is sigma = 88 +- 20 km/sec x (R/7 Mpc). The best agreement with
observations is found for LGs selected in the CDM cosmology in
environments with -0.1 <delta_rho/rho < 0.6 on scales of 7 Mpc, in agreement
with existing observational estimates on the local matter density.
These results provide new, independent evidence for the presence of dark
energy on scales of few Mpc, corroborating the evidence gathered from
observations of distant objects and the early Universe.Comment: 8 pages, 6 figures, minor changes to match the accepted version by
MNRA
Systematics of Stopping and Flow in Au+Au Collisions
Excitation functions of flow and stopping observables for the Au+Au system at
energies from 40 to 1500 MeV per nucleon are presented. The systematics were
obtained by merging the results of the INDRA and FOPI experiments, both
performed at the GSI facility. The connection to the nuclear equation of state
is discussed.Comment: Contribution to the WCI book "Dynamics and Thermodynamics with
Nucleonic Degrees of Freedom
The origin of carbon: Low-mass stars and an evolving, initially top-heavy IMF?
Multi-zone chemical evolution models (CEMs), differing in the nucleosynthesis
prescriptions (yields) and prescriptions of star formation, have been computed
for the Milky Way. All models fit the observed O/H and Fe/H gradients well and
reproduce the main characteristics of the gas distribution, but they are also
designed to do so. For the C/H gradient the results are inconclusive with
regards to yields and star formation. The C/Fe and O/Fe vs. Fe/H, as well as
C/O vs. O/H trends predicted by the models for the solar neighbourhood zone
were compared with stellar abundances from the literature. For O/Fe vs. Fe/H
all models fit the data, but for C/O vs. O/H, only models with increased carbon
yields for zero-metallicity stars or an evolving initial mass function provide
good fits. Furthermore, a steep star formation threshold in the disc can be
ruled out since it predicts a steep fall-off in all abundance gradients beyond
a certain galactocentric distance (~ 13 kpc) and cannot explain the possible
flattening of the C/H and Fe/H gradients in the outer disc seen in
observations. Since in the best-fit models the enrichment scenario is such that
carbon is primarily produced in low-mass stars, it is suggested that in every
environment where the peak of star formation happened a few Gyr back in time,
winds of carbon-stars are responsible for most of the carbon enrichment.
However, a significant contribution by zero-metallicity stars, especially at
very early stages, and by winds of high-mass stars, which are increasing in
strength with metallicity, cannot be ruled out by the CEMs presented here. In
the solar neighbourhood, as much as 80%, or as little as 40% of the carbon may
have been injected to the interstellar medium by low- and intermediate-mass
stars. The stellar origin of carbon remains an open question, although
production in low- and intermediate-mass stars appears to be the simplest
explanation of observed carbon abundance trends.Comment: 13 pages, 9 figures. Accepted by Astronomy & Astrophysic
ORIGAMI: Delineating Halos using Phase-Space Folds
We present the ORIGAMI method of identifying structures, particularly halos,
in cosmological N-body simulations. Structure formation can be thought of as
the folding of an initially flat three-dimensional manifold in six-dimensional
phase space. ORIGAMI finds the outer folds that delineate these structures.
Halo particles are identified as those that have undergone shell-crossing along
3 orthogonal axes, providing a dynamical definition of halo regions that is
independent of density. ORIGAMI also identifies other morphological structures:
particles that have undergone shell-crossing along 2, 1, or 0 orthogonal axes
correspond to filaments, walls, and voids respectively. We compare this method
to a standard Friends-of-Friends halo-finding algorithm and find that ORIGAMI
halos are somewhat larger, more diffuse, and less spherical, though the global
properties of ORIGAMI halos are in good agreement with other modern
halo-finding algorithms.Comment: 11 pages, 14 figures; matches version accepted to Ap
Realism, Instrumentalism, and Scientific Symbiosis: Psychological Theory as a search for truth and the discovery of solutions
Scientific realism holds that scientific theories are approximations of universal truths about reality, whereas scientific instrumentalism posits that scientific theories are intellectual structures that provide adequate predictions of what is observed and useful frameworks for answering questions and solving problems in a given domain. These philosophical perspectives have different strengths and weaknesses and have been regarded as incommensurate: Scientific realism fosters theoretical rigor, verifiability, parsimony, and debate, whereas scientific instrumentalism fosters theoretical innovation, synthesis, generativeness, and scope. The authors review the evolution of scientific realism and instrumentalism in psychology and propose that the categorical distinction between the 2 is overstated as a prescription for scientific practice. The authors propose that the iterative deployment of these 2 perspectives, just as the iterative application of inductive and deductive reasoning in science, may promote more rigorous, integrative, cumulative, and useful scientific theories
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