11,236 research outputs found
Town planning and public housing
During the last seven years, Spain has experience importans legislativies changes in land and housing materia. The land law of 1990, conceive the urbanistic proficience as colectivity result and the cession of part of this proficience to the land owner. This law changes the point of view about the land ownership. The use of this legislation with the objetive to maximice the colectivity utility to a minimun ejecutation cost and the transfer of the proficience from some town zones to others, building systems of distribution of charges and benefits. The city of Cadiz is a particular case where is used and checked. With the housing legislation has been posible the creation of public housing companies, perfect complement to the public intervencion in thats materials. A special case is the San Fernando public housing company (Cadiz) with the objetive of intervention in the low rent housing market without cost for the Local Administration. Keywords: Town Planning, Public Intervention, Housing.
Constraining the halo mass function with observations
The abundances of dark matter halos in the universe are described by the halo
mass function (HMF). It enters most cosmological analyses and parametrizes how
the linear growth of primordial perturbations is connected to these abundances.
Interestingly, this connection can be made approximately cosmology independent.
This made it possible to map in detail its near-universal behavior through
large-scale simulations. However, such simulations may suffer from systematic
effects, especially if baryonic physics is included. In this paper we ask how
well observations can constrain directly the HMF. The observables we consider
are galaxy cluster number counts, galaxy cluster power spectrum and lensing of
type Ia supernovae. Our results show that DES is capable of putting the first
meaningful constraints on the HMF, while both Euclid and J-PAS can give
stronger constraints, comparable to the ones from state-of-the-art simulations.
We also find that an independent measurement of cluster masses is even more
important for measuring the HMF than for constraining the cosmological
parameters, and can vastly improve the determination of the halo mass function.
Measuring the HMF could thus be used to cross-check simulations and their
implementation of baryon physics. It could even, if deviations cannot be
accounted for, hint at new physics.Comment: v2: small improvements to the text; matches accepted version. 13
pages, 8 figure
Turning noise into signal: learning from the scatter in the Hubble diagram
The supernova (SN) Hubble diagram residual contains valuable information on
both the present matter power spectrum and its growth history. In this paper we
show that this information can be retrieved with precision by combining both
peculiar velocity and weak-lensing analysis on the data. To wit, peculiar
velocity induces correlations on the nearby SN while lensing induces a
non-Gaussian dispersion in faraway objects. We show that both effects have
almost orthogonal degeneracies and discuss how they can be extracted
simultaneously from the data. We analyze the JLA supernova catalog in a
14-dimensional parameter space, assuming a flexible growth-rate index .
We arrive at the following marginalized constraints: and . Assuming instead GR
as the correct gravitation theory (and thus ), the
constraints in tighten further: .
We show that these constraints complement well the ones obtained from other
datasets and that they could improve substantially with more SNe.Comment: v2: Real data results corrected; forecast for future data added;
discussion extended. v3: Improved discussion; matches published version. 8
figs 15 page
Dirac points merging and wandering in a model Chern insulator
We present a model for a Chern insulator on the square lattice with complex
first and second neighbor hoppings and a sublattice potential which displays an
unexpectedly rich physics. Similarly to the celebrated Haldane model, the
proposed Chern insulator has two topologically non-trivial phases with Chern
numbers . As a distinctive feature of the present model, phase
transitions are associated to Dirac points that can move, merge and split in
momentum space, at odds with Haldane's Chern insulator where Dirac points are
bound to the corners of the hexagonal Brillouin zone. Additionally, the
obtained phase diagram reveals a peculiar phase transition line between two
distinct topological phases, in contrast to the Haldane model where such
transition is reduced to a point with zero sublattice potential. The model is
amenable to be simulated in optical lattices, facilitating the study of phase
transitions between two distinct topological phases and the experimental
analysis of Dirac points merging and wandering
Optimization of the ionization time of an atom with tailored laser pulses: a theoretical study
How fast can a laser pulse ionize an atom? We address this question by
considering pulses that carry a fixed time-integrated energy per-area, and
finding those that achieve the double requirement of maximizing the ionization
that they induce, while having the shortest duration. We formulate this
double-objective quantum optimal control problem by making use of the Pareto
approach to multi-objetive optimization, and the differential evolution genetic
algorithm. The goal is to find out how much a precise time-profiling of
ultra-fast, large-bandwidth pulses may speed up the ionization process with
respect to simple-shape pulses. We work on a simple one-dimensional model of
hydrogen-like atoms (the P\"oschl-Teller potential), that allows to tune the
number of bound states that play a role in the ionization dynamics. We show how
the detailed shape of the pulse accelerates the ionization process, and how the
presence or absence of bound states influences the velocity of the process
Constraining the growth of perturbations with lensing of supernovae
A recently proposed technique allows one to constrain both the background and
perturbation cosmological parameters through the distribution function of
supernova Ia apparent magnitudes. Here we extend this technique to alternative
cosmological scenarios, in which the growth of structure does not follow the
CDM prescription. We apply the method first to the supernova data
provided by the JLA catalog combined with all the current independent redshift
distortion data and with low-redshift cluster data from Chandra and show that
although the supernovae alone are not very constraining, they help in reducing
the confidence regions. Then we apply our method to future data from LSST and
from a survey that approximates the Euclid satellite mission. In this case we
show that the combined data are nicely complementary and can constrain the
normalization and the growth rate index to within
and , respectively. In particular, the LSST supernova catalog is forecast
to give the constraint . We also
report on constraints relative to a step-wise parametrization of the growth
rate of structures. These results show that supernova lensing serves as a good
cross-check on the measurement of perturbation parameters from more standard
techniques.Comment: 9 pages, 7 figures, matches version accepted for publication in
MNRAS. Added appendix with fits of lensing moments as function of (z,
\sigma_8, \gamma). The updated turboGL 3.0 code can be downloaded at
http://www.turbogl.or
Retail trade as a tool to create a border identity
Desde sempre as localidades próximas das fronteiras estabeleceram relações entre as suas populações - familiares, de trabalho e, talvez as mais antigas, comerciais. Desde sempre o factor barreira, induzido pela fronteira, não representou obstáculo à s relações entre povos. Dependendo da porosidade da fronteira, as relações podem tornar-se mais ou menos intensas, mais ou menos tranquilas, mas nunca nulas. O contrabando e o aproveitamento das vantagens comparativas entre dois paÃses proporcionaram sempre contactos e uma alteridade que potencia a formação de uma identidade na população, que não deixando de ser nacional, é, simultaneamente, transfronteiriça.
No caso da fronteira interna da PenÃnsula Ibérica, sempre se puderam verificar relações comerciais que, essencialmente após a adesão dos dois paÃses à U. Europeia, e mais concretamente a partir de Schengen, se intensificaram, devido à diluição do efeito de barreira. No caso do polÃgono formado por Portalegre/Elvas/Badajoz/Valência de Alcântara verifica-se que o factor de maior aproximação entre as populações é o comércio a retalho e que este, directa ou indirectamente, influencia o crescimento e a expansão urbanos
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