119 research outputs found
Single Stellar Populations in the Near-Infrared - I. Preparation of the IRTF spectral stellar library
We present a detailed study of the stars of the IRTF spectral library to
understand its full extent and reliability for use with Stellar Population (SP)
modeling. The library consist of 210 stars, with a total of 292 spectra,
covering the wavelength range of 0.94 to 2.41 micron at a resolution R = 2000.
For every star we infer the effective temperature (Teff), gravity (logg) and
metallicity ([Z/Zsun]) using a full-spectrum fitting approach in a section of
the K band (2.19 to 2.34 micron) and temperature-NIR colour relations. We test
the flux calibration of these stars by calculating their integrated colours and
comparing them with the Pickles library colour-temperature relations. We also
investigate the NIR colours as a function of the calculated effective
temperature and compared them in colour-colour diagrams with the Pickles
library. This latter test shows a good broad-band flux calibration, important
for the SP models. Finally, we measure the resolution R as a function of
wavelength. We find that the resolution increases as a function of lambda from
about 6 angstrom in J to 10 angstrom in the red part of the K-band. With these
tests we establish that the IRTF library, the largest currently available
general library of stars at intermediate resolution in the NIR, is an excellent
candidate to be used in stellar population models. We present these models in
the next paper of this series.Comment: 17 pages, 19 figures. Accepted for publication in Astronomy and
Astrophysic
Dealing with change and uncertainty within the regulatory frameworks for flood defense infrastructure in selected European countries
Whereas existing literature on the interactions between law, adaptive governance and resilience in the water sector often focuses on quality or supply issues, this paper addresses adaptation in national water laws in relation to increasing flood risks. In particular, this paper analyzes the extent to which legal rules governing flood defense infrastructure in a selection of European countries (Sweden, France, England and the Netherlands) allow for response and adaptation to change and uncertainty. While there is evidence that the legal rules on the development of new infrastructure require that changing conditions be considered, the adaptation of existing infrastructure is a more complicated matter. Liability rules fail to adequately address damages resulting from causes external to the action or inaction of owners and managers, in particular extreme events. A trend towards clearer, and in some cases, increased public powers to ensure the safety of flood defense infrastructure is observed. The paper concludes that legal rules should ensure not only that decisions to build flood defenses are based on holistic and future-oriented assessments, but also that this is reflected in the implementation and operation of these structures
Carbon stars in the X-shooter Spectral Library
We provide a new collection of spectra of 35 carbon stars obtained with the
ESO/VLT X-shooter instrument as part of the X-shooter Spectral Library project.
The spectra extend from 0.3m to 2.4m with a resolving power above
8000. The sample contains stars with a broad range of (J-K) color and
pulsation properties located in the Milky Way and the Magellanic Clouds. We
show that the distribution of spectral properties of carbon stars at a given
(J-K) color becomes bimodal (in our sample) when (J-K) is larger than about
1.5. We describe the two families of spectra that emerge, characterized by the
presence or absence of the absorption feature at 1.53m, generally
associated with HCN and CH. This feature appears essentially only in
large-amplitude variables, though not in all observations. Associated spectral
signatures that we interpret as the result of veiling by circumstellar matter,
indicate that the 1.53m feature might point to episodes of dust production
in carbon-rich Miras.Comment: 29 pages, 21 figures, 9 tables, Accepted for publication in A&
Copper(II)-Bis(Thiosemicarbazonato) Complexes as Antibacterial Agents: Insights into Their Mode of Action and Potential as Therapeutics
There is increasing interest in the use of lipophilic copper (Cu)-containing complexes to combat bacterial infections. In this work, we showed that Cu complexes with bis(thiosemicarbazone) ligands [Cu(btsc)] exert antibacterial activity against a range of medically significant pathogens. Previous work using Neisseria gonorrhoeae showed that Cu(btsc) complexes may act as inhibitors of respiratory dehydrogenases in the electron transport chain. We now show that these complexes are also toxic against pathogens that lack a respiratory chain. Respiration in Escherichia coli was slightly affected by Cu(btsc) complexes, but our results indicate that, in this model bacterium, the complexes act primarily as agents that deliver toxic Cu ions efficiently into the cytoplasm. Although the chemistry of Cu(btsc) complexes may dictate their mechanism of action, their efficacy depends heavily on bacterial physiology. This is linked to the ability of the target bacterium to tolerate Cu and, additionally, the susceptibility of the respiratory chain to direct inhibition by Cu(btsc) complexes. The physiology of N. gonorrhoeae, including multidrug-resistant strains, makes it highly susceptible to damage by Cu ions and Cu(btsc) complexes, highlighting the potential of Cu(btsc) complexes (and Cu-based therapeutics) as a promising treatment against this important bacterial pathogen
El enfoque regional en la problemática de la preservación el caso norte cordobés
We develop here a new concept of architectural patrimony, which includes not only monuments but also places with special meaning for their inhabitants incorporating urban environments and even complete villages and regions as things to be preserved. This idea is based on a multiple evaluation of the regional and historical site, which is looked from different points of views: esthetic, cultural, landscaping, environmental as well as in terms of its economic and social meaning for its development.Se trata de un nuevo concepto de patrimonio arquitectónico, relacionado no exclusivamente a los monumentos sino que alcanza el concepto de lugar y de identidad de los habitantes con él, incorporando como objetos a preservar sectores urbanos o poblaciones completas.
Se apoya en una doble lectura valorativa de los lugares histórico-regionales considerándolos también en términos de su significado económico-social para el desarrollo
The European Union approach to flood risk management and improving societal resilience: lessons from the implementation of the Floods Directive in six European countries
Diversity in flood risk management approaches is often considered to be a strength. However in some national settings, and especially for transboundary rivers, variability and the incompatibility of approaches can reduce the effectiveness of flood risk management. Placed in the context of increasing flood risks, as well as the potential for flooding to undermine the European Union's sustainable development goals, a desire to increase societal resilience to flooding has prompted the introduction of a common European Framework. This paper provides a legal and policy analysis of the implementation of the Floods Directive (2007/60/EC) in six countries; Belgium (Flemish Region), England, France, the Netherlands, Poland and Sweden. Evaluation criteria from existing legal and policy literature frame the study of the Directive and its impact on enhancing or constraining societal resilience by using an adaptive governance approach. These criteria are initially used to analyze the key components of the EU approach, before providing insight of the implementation of the Directive at a national level. Similarities and differences in the legal translation of European goals into existing flood risk management are analyzed alongside their relative influence on policy and practice. The research highlights that the impact of the Floods Directive on increasing societal resilience has been nationally variable, in part due to its focus on procedural obligations, rather than on more substantive requirements. Analysis shows that despite a focus on transboundary river basin management, in some cases existing traditions of flood risk management, have overridden objectives to harmonize flood risk management. This could be strengthened by requiring more stringent cooperation and providing the competent authorities in International River Basins Districts with more power. Despite some shortcomings in directly impacting flood risk outcomes, the Directive has positively stimulated discussion and flood risk management planning in countries that were perhaps lagging behind
Stellar population models based on the SDSS-IV MaStar library of stellar spectra. I. Intermediate-age/old models
We use the first release of the SDSS/MaStar stellar library comprising ~9000,
high S/N spectra, to calculate integrated spectra of stellar population models.
The models extend over the wavelength range 0.36-1.03 micron and share the same
spectral resolution (R~1800) and flux calibration as the SDSS-IV/MaNGA galaxy
data. The parameter space covered by the stellar spectra collected thus far
allows the calculation of models with ages and chemical composition in the
range t>200 Myr, -2 <=[Z/H]<= + 0.35, which will be extended as MaStar
proceeds. Notably, the models include spectra for dwarf Main Sequence stars
close to the core H-burning limit, as well as spectra for cold, metal-rich
giants. Both stellar types are crucial for modelling lambda>0.7 micron
absorption spectra. Moreover, a better parameter coverage at low metallicity
allows the calculation of models as young as 500 Myr and the full account of
the Blue Horizontal Branch phase of old populations. We present models adopting
two independent sets of stellar parameters (T_eff, logg, [Z/H]). In a novel
approach, their reliability is tested 'on the fly' using the stellar population
models themselves. We perform tests with Milky Way and Magellanic Clouds
globular clusters, finding that the new models recover their ages and
metallicities remarkably well, with systematics as low as a few per cent for
homogeneous calibration sets. We also fit a MaNGA galaxy spectrum, finding
residuals of the order of a few per cent comparable to the state-of-art models,
but now over a wider wavelength range.Comment: 37 pages, 31 figures, MNRAS in press, models available at
http://www.icg.port.ac.uk/masta
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