319 research outputs found
An Integrated Approach to Flood Risk Management: A Case Study of Navaluenga (Central Spain)
Flood risk management decisions require the rational assessment of mitigation strategies. This is a complex decision-making process involving many uncertainties. This paper presents a case study where a cost-benefit based methodology is used to define the best intervention measures for flood-risk mitigation in central Spain. Based on different flood hazard scenarios, several structural measures considered by the local Basin Water Authority and others defined by engineering criteria were checked for operability. Non-systematic data derived from dendrogeomorphological analysis of riparian trees were included in the flood frequency analysis. Flood damage was assessed by means of depth-damage functions, and flooded urban areas were obtained by applying a hydraulic model. The best defense strategies were obtained by a cost-benefit procedure, where uncertainties derived from each analytical process were incorporated based on a stochastic approach to estimate expected economic losses. The results showed that large structural solutions are not economically viable when compared with other smaller structural measures, presumably because of the pre-established location of dams in the upper part of the basin which do not laminate the flow generated by the surrounding catchment to Navalueng
On the properties of fractal cloud complexes
We study the physical properties derived from interstellar cloud complexes
having a fractal structure. We first generate fractal clouds with a given
fractal dimension and associate each clump with a maximum in the resulting
density field. Then, we discuss the effect that different criteria for clump
selection has on the derived global properties. We calculate the masses, sizes
and average densities of the clumps as a function of the fractal dimension
(D_f) and the fraction of the total mass in the form of clumps (epsilon). In
general, clump mass does not fulfill a simple power law with size of the type
M_cl ~ (R_cl)**(gamma), instead the power changes, from gamma ~ 3 at small
sizes to gamma<3 at larger sizes. The number of clumps per logarithmic mass
interval can be fitted to a power law N_cl ~ (M_cl)**(-alpha_M) in the range of
relatively large masses, and the corresponding size distribution is N_cl ~
(R_cl)**(-alpha_R) at large sizes. When all the mass is forming clumps
(epsilon=1) we obtain that as D_f increases from 2 to 3 alpha_M increases from
~0.3 to ~0.6 and alpha_R increases from ~1.0 to ~2.1. Comparison with
observations suggests that D_f ~ 2.6 is roughly consistent with the average
properties of the ISM. On the other hand, as the fraction of mass in clumps
decreases (epsilon<1) alpha_M increases and alpha_R decreases. When only ~10%
of the complex mass is in the form of dense clumps we obtain alpha_M ~ 1.2 for
D_f=2.6 (not very different from the Salpeter value 1.35), suggesting this a
likely link between the stellar initial mass function and the internal
structure of molecular cloud complexes.Comment: 32 pages, 13 figures, 1 table. Accepted for publication in Ap
The Calar Alto Legacy Integral Field Area Survey: extended and remastered data release
This paper describes the extended data release of the Calar Alto Legacy
Integral Field Area (CALIFA) survey (eDR). It comprises science-grade quality
data for 895 galaxies obtained with the PMAS/PPak instrument at the 3.5 m
telescope at the Calar Alto Observatory along the last 12 years, using the V500
setup (3700-7500{\AA}, 6{\AA}/FWHM) and the CALIFA observing strategy. It
includes galaxies of any morphological type, star-formation stage, a wide range
of stellar masses (10 10 Msun ), at an average redshift of
0.015 (90\% within 0.005z0.05). Primarily selected based on the
projected size and apparent magnitude, we demonstrate that it can be volume
corrected resulting in a statistically limited but representative sample of the
population of galaxies in the nearby Universe. All the data were homogeneous
re-reduced, introducing a set of modifications to the previous reduction. The
most relevant is the development and implementation of a new
cube-reconstruction algorithm that provides with an (almost) seeing-limited
spatial resolution (FWHM PSF 1.0").To illustrate the usability and
quality of the data, we extracted two aperture spectra for each galaxy (central
1.5" and fully integrated), and analyze them using pyFIT3D. We obtain a set of
observational and physical properties of both the stellar populations and the
ionized gas, that have been compared for the two apertures, exploring their
distributions as a function of the stellar masses and morphologies of the
galaxies, comparing with recent results in the literature. DATA RELEASE:
http://ifs.astroscu. unam.mx/CALIFA_WEB/public_html/Comment: 30 pages, 26 figures, accepted for publishing in the MNRA
Ionized gas kinematics of galaxies in the CALIFA survey I: Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems
This work provides an overall characterization of the kinematic behavior of
the ionized gas of the galaxies included in the Calar Alto Legacy Integral
field Area (CALIFA), offering kinematic clues to potential users of this survey
for including kinematical criteria for specific studies. From the first 200
galaxies observed by CALIFA, we present the 2D kinematic view of the 177
galaxies satisfying a gas detection threshold. After removing the stellar
contribution, we used the cross-correlation technique to obtain the radial
velocity of the dominant gaseous component. The main kinematic parameters were
directly derived from the radial velocities with no assumptions on the internal
motions. Evidence of the presence of several gaseous components with different
kinematics were detected by using [OIII] profiles. Most objects in the sample
show regular velocity fields, although the ionized-gas kinematics are rarely
consistent with simple coplanar circular motions. 35% of the objects present
evidence of a displacement between the photometric and kinematic centers larger
than the original spaxel radii. Only 17% of the objects in the sample exhibit
kinematic lopsidedness when comparing receding and approaching sides of the
velocity fields, but most of them are interacting galaxies exhibiting nuclear
activity. Early-type galaxies in the sample present clear photometric-kinematic
misaligments. There is evidence of asymmetries in the emission line profiles
suggesting the presence of kinematically distinct gaseous components at
different distances from the nucleus. This work constitutes the first
determination of the ionized gas kinematics of the galaxies observed in the
CALIFA survey. The derived velocity fields, the reported kinematic
peculiarities and the identification of the presence of several gaseous
components might be used as additional criteria for selecting galaxies for
specific studies.Comment: 38 pages, 16 figures, 4 tables. Paper accepted for publication in A&
Inflation and nonequilibrium renormalization group
We study de spectrum of primordial fluctuations and the scale dependence of
the inflaton spectral index due to self-interactions of the field. We compute
the spectrum of fluctuations by applying nonequilibrium renormalization group
techniques.Comment: 6 pages, 1 figure, submitted to J. Phys.
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