20,764 research outputs found
Developing a site-conditions map for seismic hazard Assessment in Portugal
The evaluation of site effects on a broad scale is a critical issue for seismic hazard and risk assessment, land use planning and emergency planning. As characterization of site conditions based on the shear-wave velocity has become increasingly important, several methods have been proposed in the literature to estimate its average over the first thirty meters (Vs30) from more extensively available data. These methods include correlations with geologic-geographic defined units and topographic slope. In this paper we present the first steps towards the development of a site–conditions map for Portugal, based on a regional database of shear-wave velocity data, together with geological, geographic, and lithological information. We computed Vs30 for each database site and classified it according to the corresponding geological-lithological information using maps at the smallest scale available (usually 1:50000). We evaluated the consistency of Vs30 values within generalized-geological classes, and assessed the performance of expedient methodologies proposed in the literature
Vanishing Viscosity Limits and Boundary Layers for Circularly Symmetric 2D Flows
We continue the work of Lopes Filho, Mazzucato and Nussenzveig Lopes [LMN],
on the vanishing viscosity limit of circularly symmetric viscous flow in a disk
with rotating boundary, shown there to converge to the inviscid limit in
-norm as long as the prescribed angular velocity of the
boundary has bounded total variation. Here we establish convergence in stronger
and -Sobolev spaces, allow for more singular angular velocities
, and address the issue of analyzing the behavior of the boundary
layer. This includes an analysis of concentration of vorticity in the vanishing
viscosity limit. We also consider such flows on an annulus, whose two boundary
components rotate independently.
[LMN] Lopes Filho, M. C., Mazzucato, A. L. and Nussenzveig Lopes, H. J.,
Vanishing viscosity limit for incompressible flow inside a rotating circle,
preprint 2006
Experimental determination of the non-extensive entropic parameter
We show how to extract the parameter from experimental data, considering
an inhomogeneous magnetic system composed by many Maxwell-Boltzmann homogeneous
parts, which after integration over the whole system recover the Tsallis
non-extensivity. Analyzing the cluster distribution of
LaSrMnO manganite, obtained through scanning tunnelling
spectroscopy, we measure the parameter and predict the bulk magnetization
with good accuracy. The connection between the Griffiths phase and
non-extensivity is also considered. We conclude that the entropic parameter
embodies information about the dynamics, the key role to describe complex
systems.Comment: Submitted to Phys. Rev. Let
GeMs/GSAOI observations of La Serena 94: an old and far open cluster inside the solar circle
Physical properties were derived for the candidate open cluster La Serena 94,
recently unveiled by the VVV collaboration. Thanks to the exquisite angular
resolution provided by GeMS/GSAOI, we could characterize this system in detail,
for the first time, with deep photometry in JHK - bands. Decontaminated
JHK diagrams reach about 5 mag below the cluster turnoff in H. The locus
of red clump giants in the colour - colour diagram, together with an extinction
law, was used to obtain an average extinction of . The
same stars were considered as standard - candles to derive the cluster
distance, kpc. Isochrones were matched to the cluster colour -
magnitude diagrams to determine its age, , and
metallicity, . A core radius of pc was
found by fitting King models to the radial density profile. By adding up the
visible stellar mass to an extrapolated mass function, the cluster mass was
estimated as M, consistent with an
integrated magnitude of and a tidal radius of
pc. The overall characteristics of La Serena 94 confirm that
it is an old open cluster located in the Crux spiral arm towards the fourth
Galactic quadrant and distant kpc from the Galactic centre. The
cluster distorted structure, mass segregation and age indicate that it is a
dynamically evolved stellar system.Comment: 16 pages, 24 figures, 2 Tables, accepted by MNRAS; corrected typo
Stellar parameters for stars of the CoRoT exoplanet field
Aims:To support the computation and evolutionary interpretation of periods
associated with the rotational modulation, oscillations, and variability of
stars located in the CoRoT fields, we are conducting a spectroscopic survey for
stars located in the fields already observed by the satellite. These
observations allow us to compute physical and chemical parameters for our
stellar sample. Method: Using spectroscopic observations obtained with UVES/VLT
and Hydra/Blanco, and based on standard analysis techniques, we computed
physical and chemical parameters (, , ,
, , , and ) for a large
sample of CoRoT targets. Results: We provide physical and chemical parameters
for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in
our sample are located in different evolutionary stages, ranging from the main
sequence to the red giant branch, and range in spectral type from F to K. The
physical and chemical properties for the stellar sample are in agreement with
typical values reported for FGK stars. However, we report three stars
presenting abnormal lithium behavior in the CoRoT fields. These parameters
allow us to properly characterize the intrinsic properties of the stars in
these fields. Our results reveal important differences in the distributions of
metallicity, , and evolutionary status for stars belonging to
different CoRoT fields, in agreement with results obtained independently from
ground-based photometric surveys. Conclusions: Our spectroscopic catalog, by
providing much-needed spectroscopic information for a large sample of CoRoT
targets, will be of key importance for the successful accomplishment of several
different programs related to the CoRoT mission, thus it will help further
boost the scientific return associated with this space mission.Comment: 43 pages, 17 figures, accepted for publication in A&
Exploring the relationship between older parents and their middle-aged children: a scoping review
info:eu-repo/semantics/publishedVersio
Determinação da Carga Alergénica (Ole e1) Presente no Ar Atmosférico na Região de Évora: Correlação com o conteúdo polínico de Olea
Introdução: Em Portugal, o pólen da oliveira (Olea europaea) constitui uma das fontes mais relevantes de aero-alergénios, sendo uma causa frequente de polinose na região Mediterrânica, onde o Ole e 1 é um alergeno major. Apesar de se julgar apenas associado aos grãos de pólen, desconhece-se a variabilidade inter-anual da carga alergénica do pólen e ainda existe alguma controvérsia sobre a forma como este aeroalergeno se distribui no ar atmosférico.
Objectivo: Este trabalho teve como objectivos: i) determinar a fracção dos bioaerossóis mais rica em Ole e 1; ii) avaliar a correlação dos conteúdos diários de pólen e aeroalergeno no ar atmosférico; iii) avaliar variação anual da carga alergénica do pólen.
Métodos: Os aeroalergenos foram captados utilizando um colector de impacto CHEMVOL equipado com dois filtros com capacidade para reter partículas de diferentes dimensões: PM>10µm e 10µm>PM>2,5µm. Após 24h os filtros foram retirados, a fracção proteica foi extraída e os alergenos quantificados por ELISA. Simultaneamente o pólen foi monitorizado pela tecnologia padrão utilizando um colector volumétrico Burkard 7-Day Recording Volumetric Spore Trap. Os colectores foram ambos colocados numa mesma plataforma a 17m de altura, e a ≈3-4m um do outro.
Resultados: Entre 2009 e 2011, registou-se uma variação inter-anual quer do perfil quer da duração da época polínica (39, 47 e 45 dias, respectivamente). O conteúdo polínico total no ar atmosférico também foi variável no intervalo de 7240 a 12524 grãos/m3. Mais de 90% do alergeno foi encontrado na fracção de bioaerossóis de PM>10µm. O conteúdo em Ole e 1 foi directamente proporcional ao número de grãos de pólen no ar atmosférico, tendo-se encontrado uma correlação positiva entre os valores diários dos dois parâmetros. Comparando as épocas estudadas, os conteúdos totais de Ole e1 e de pólen não foram proporcionais, tendo-se observado que a carga alergénica por grão de pólen variou mais de 3x.
Conclusões: Estes resultados sugerem que o Ole e 1 está preferencialmente associado aos grãos de pólen. Os conteúdos em pólen e Ole e 1 variaram inter-anualmente, tendo a carga alergénica dos grãos de pólen sido diferente. Este trabalho poderá assim contribuir para o desenvolvimento de um indicador que permita melhorar a previsão do risco de exposição a aeroalergenos.
Agradecimentos: Este foi realizado no âmbito do projecto europeu HIALINE (Executive Agency for Health and Consumers, grant agreement No 2008 11 07)
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