1,767 research outputs found
Anisakis infection in allis shad, Alosa alosa (Linnaeus, 1758), and twaite shad, Alosa fallax (Lacépède, 1803), from Western Iberian Peninsula Rivers : zoonotic and ecological implications
Acknowledgments The authors would like to thank M. N. Cueto and J.M. Antonio (ECOBIOMAR) for their excellent technical support and also Rodrigo López for making the map of the study area. We also thank the personal of the Vigo IEO, for providing information about shad captures at sea collected on the basis of national program (AMDES) included in the European Data Collection Framework (DCF) project. We are also grateful to Comandancia Naval de Tui for providing fishing data. M. Bao is supported by a PhD grant from the University of Aberdeen and also by financial support of the contract from the EU Project PARASITE (grant number 312068). This study was partially supported by a PhD grant from the Portuguese Foundation for Science and Technology (FCT) SFRH/BD/44892/2008) and partially supported by the European Regional Development Fund (ERDF) through the COMPETE—Operational Competitiveness Programme and national funds through Foundation for Science and Technology (FCT), under the project BPEst-C/MAR/ LA0015/2013. The authors thank the staff of the Station of Hydrobiology of the USC BEncoro do Con^ due their participation in the surveys. This work has been partially supported by the project 10PXIB2111059PR of the Xunta de Galicia and the project MIGRANET of the Interreg IV BSUDOE (South-West Europe) Territorial Cooperation Programme (SOE2/P2/E288). D.J. Nachón is supported by a PhD grant from the Xunta de Galicia (PRE/2011/198)Peer reviewedPostprin
On the validity of the 630 nm Fe I nm lines for the magnetometry of the internetwork quiet Sun
The purpose of this work is to analyze the reliability of the magnetic field
strengths inferred from the 630 nm pair of Fe I lines at internetwork quiet Sun
regions. Some numerical experiments have been performed that demonstrate the
inability of these lines to recover the magnetic field strength in such low
flux solar regions. It is shown how different model atmospheres, with magnetic
field strengths ranging from few hundred Gauss to kiloGauss, give rise to
Stokes profiles that can not be distinguished. The reasons for this degeneracy
are discussed.Comment: Accepted for publication in A&
Low-lying magnetic loops in the solar internetwork
The aim of this work is to study the structure of the magnetic field vector
in the internetwork and search for the presence of small-scale loops. We invert
1.56 micron spectropolarimetric observations of internetwork regions at disc
centre by applying the SIR code. This allows us to recover the atmospheric
parameters that play a role in the formation of these spectral lines. We are
mainly interested in the structure of the magnetic field vector. We find that
many opposite polarity elements of the internetwork are connected by short
(2-6''), low-lying (photospheric) loops. These loops connect at least the 10-20
% of the internetwork flux visible in our data. Also we have some evidence that
points towards a dynamic scenario which can be produced by the emergence of
internetwork magnetic flux.Comment: Accepted for publication in A&A letter
Combining magneto-hydrostatic constraints with Stokes profiles inversions
Inversion codes for the polarized radiative transfer equation can be used to
infer the temperature , line-of-sight velocity , and magnetic
field as a function of the continuum optical-depth .
However, they do not directly provide the gas pressure or density
. In order to obtain these latter parameters, inversion codes rely
instead on the assumption of hydrostatic equilibrium (HE) in addition to the
equation of state (EOS). Unfortunately, the assumption of HE is rather
unrealistic across magnetic field lines. This is because the role of the
Lorentz force, among other factors, is neglected. This translates into an
inaccurate conversion from optical depth to geometrical height
. We aim at improving this conversion via the application of
magneto-hydrostatic (MHS) equilibrium instead of HE. We develop a method to
solve the momentum equation under MHS equilibrium (i.e., taking the Lorentz
force into account) in three dimensions. The method is based on the solution of
a Poisson-like equation. Considering the gas pressure and density
from three-dimensional magneto-hydrodynamic (MHD) simulations of
sunspots as a benchmark, we compare the results from the application of HE and
MHS equilibrium. We find that HE retrieves the gas pressure and density within
an order of magnitude of the MHD values in only about 47 \% of the domain. This
translates into an error of about km in the determination of the
conversion. On the other hand, the application of MHS
equilibrium allows determination of and within an order of
magnitude in 84 \% of the domain. In this latter case, the
conversion is obtained with an accuracy of km.Comment: Accepted for publication in Astronomy \& Astrophysics. 12 pages, 10
figure
Fluxtube model atmospheres and Stokes V zero-crossing wavelengths
First results of the inversion of Stokes I and V profiles from plage regions
near disk center are presented. Both low and high spatial resolution spectra of
FeI 6301.5 and FeI 6302.5 A obtained with the Advanced Stokes Polarimeter (ASP)
have been considered for analysis. The thin flux tube approximation,
implemented in an LTE inversion code based on response functions, is used to
describe unresolved magnetic elements. The code allows the simultaneous and
consistent inference of all atmospheric quantities determining the radiative
transfer with the sole assumption of hydrostatic equilibrium. By considering
velocity gradients within the tubes we are able to match the full ASP Stokes
profiles. The magnetic atmospheres derived from the inversion are characterized
by the absence of significant motions in high layers and strong velocity
gradients in deeper layers. These are essential to reproduce the asymmetries of
the observed profiles. Our scenario predicts a shift of the Stokes V
zero-crossing wavelengths which is indeed present in observations made with the
Fourier Transform Spectrometer.Comment: To appear in ApJ Letters (1997) (in press
Estudio experimental del comportamiento a compresión de probetas de hormigón de resistencias bajas y medias confinadas con tejidos de fibras de carbono y con defectos muy importantes de ejecución
This behaviour of low- and medium-strength concrete specimens confined with carbon fibre-reinforced polymer (CFRP) was analysed in three loading cycles. In some cases, stress levels were achieved that produced intemal microcracks, which allowed residual rigidity and the behaviour of completely microcraked concrete specimens to be studied. The specimens were subsequently tested to compression to the fracture point. Specimens reinforced in accordance with no manufacturing defects (100% CFRP reinforcement) and major manufacturing defects (50% CFRP reinforcement) were assessed for effectiveness and behaviour of the confined elements in less than ideal conditions. Results show that confinement was higher in low-resistance concretes, that the behaviour of reinforced specimens was unaffected by defective implementation conditions and that the reinforced specimens were less rigid than the non-reinforced specimens when tested up to 40% of ultimate fracture strength.En este trabajo se estudia el comportamiento de hormigones de resistencias bajas y medias confinados con CFRP. Se han realizado 3 ciclos de carga llegando en algunos casos a niveles de tensión que han microfisurado internamente el hormigón, lo que ha permitido estudiar la rigidez residual y el comportamiento de probetas confinadas con el hormigón totalmente microfisurado. Posteriormente todas las probetas se han ensayado a compresión hasta rotura. Los refuerzos se han realizado con buenas condiciones de ejecución y simulando grandes defectos para poder evaluar la eficacia de los elementos confinados cuando las condiciones de ejecución no son las correctas. Los resultados muestran que el efecto de confinamiento es superior en hormigones poco resistentes, el comportamiento de las probetas reforzadas es poco sensible a grandes defectos de ejecución y su rigidez es inferior al de las probetas originales cuando se ensayan hasta el 40% de la tensión de rotura
Interplay between lattice, orbital, and magnetic degrees of freedom in the chain-polymer Cu(II) breathing crystals
The chain-polymer Cu(II) breathing crystals C21H19CuF12N4O6 were studied
using the x-ray diffraction and ab initio band structure calculations. We show
that the crystal structure modification at T=146 K, associated with the spin
crossover transition, induces the changes of the orbital order in half of the
Cu sites. This in turn results in the switch of the magnetic interaction sign
in accordance with the Goodenough-Kanamori-Andersen theory of the coupling
between the orbital and spin degrees of freedom.Comment: 6 pages, 7 figure
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