Radio emission of SN1993J. The complete picture: II. Simultaneous fit of expansion and radio light curves

We report on a simultaneous modelling of the expansion and radio light curves of SN1993J. We have developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with an standard emission model for supernovae extended with some physical considerations, as an evolution in the opacity of the ejecta material, a radial drop of the magnetic fields inside the radiating region, and a changing radial density profile of the circumstellar medium beyond day 3100 after explosion.Comment: 12 pages, 12 figures, accepted for publication in A&

Absolute kinematics of radio source components in the complete S5 polar cap sample. III. First wide-field high-precision astrometry at 15.4 GHz

We report on the first wide-field, high-precision astrometric analysis of the 13 extragalactic radio sources of the complete S5 polar cap sample at 15.4 GHz. We describe new algorithms developed to enable the use of differenced phase delays in wide-field astrometric observations and discuss the impact of using differenced phase delays on the precision of the wide-field astrometric analysis. From this global fit, we obtained estimates of the relative source positions with precisions ranging from 14 to 200 $\mu$as at 15.4 GHz, depending on the angular separation of the sources (from $\sim$1.6 to $\sim$20.8 degrees). These precisions are $\sim$10 times higher than the achievable precisions using the phase-reference mapping technique.Comment: 9 pages, 7 figure

La hegemonía cultural del glolugar: entre la relegación y la reivindicación local. El caso de Valencia

El artículo tiene por objeto abordar cómo la hegemonía del glolugar, en tanto que figura paradigmática de los procesos urbanos neoliberales, ha implicado un determinado modelo de política cultural y de desarrollo urbano que hemos podido singularizar en el caso de la ciudad de Valencia y la Ciudad de las Artes y de las Ciencias. La hegemonía cultural del glolugar no se puede entender sin enmarcarla en una tendencia global como es la extensión del urbanismo neoliberal, la ciudad es concebida como una entidad competitiva inmersa en un espacio global que promueve el mercado y la mentalidad emprendedora a través de nuevas prácticas de la gestión pública. En el caso de Valencia, el proyecto de ciudad neoliberal ha pivotado sobre los grandes proyectos y eventos, con la espectacular Ciudad de las Artes y de las Ciencias como mascarón de proa. Nuestra reflexión pretende vincular urbanismo neoliberal, política cultural y modelo de ciudad, utilizando como clave de bóveda el rol que el glolugar en nuestro caso la Ciudad de las Artes y de las Ciencias, tiene en el proceso. Sin embargo, frente a las políticas neoliberales del glolugar se ha ido conformando desde los barrios populares una serie de acciones socio-culturales desarrolladas por una red de asociaciones, grupos, colectivos e iniciativas culturales. Estas respuestas, unas más profesionales y otras más críticas con dicho modelo, ahora en crisis, proponen iniciativas culturales resistentes y alternativas

8.4GHz VLBI observations of SN2004et in NGC6946

We report on 8.4GHz Very Long Baseline Interferometry (VLBI) observations of the type II-P supernova SN2004et in the spiral galaxy NGC 6946, made on 20 February 2005 (151 days after explosion). The Very Large Array (VLA) flux density was 1.23$\pm$0.07 mJy, corresponding to an isotropic luminosity at 8.4GHz of (4.45$\pm$0.3)$\times10^{25}$ erg s$^{-1}$ Hz$^{-1}$ and a brightness temperature of (1.3$\pm$0.3)$\times10^{8}$ K. We also provide an improved source position, accurate to about 0.5 mas in each coordinate. The VLBI image shows a clear asymmetry. From model fitting of the size of the radio emission, we estimate a minimum expansion velocity of 15,700$\pm$2,000 km s$^{-1}$. This velocity is more than twice the expected mean expansion velocity estimated from a synchrotron self-absorbed emission model, thus suggesting that synchrotron self-absorption is not relevant for this supernova. With the benefit of an optical spectrum obtained 12 days after explosion, we favor an emission model which consists of two hot spots on an underlying expanding shell of width comparable to that of SN 1993J.Comment: Accepted for publication in A&A (22/05/07

The cultural hegemony of the global places: between relegation and the local claim. The case of Valencia

El artículo que presentamos tiene por objeto abordar cómo la hegemonía del glolugar, en tanto que figura paradigmática de los procesos urbanos neoliberales, ha implicado un determinado modelo de política cultural que hemos podido singularizar en el caso de la ciudad de Valencia y la Ciudad de las Artes y de las Ciencias. La hegemonía cultural del glolugar no se puede entender sin enmarcarla en una tendencia global como es la extensión del urbanismo neoliberal, la ciudad es concebida como una entidad competitiva inmersa en un espacio global que promueve el mercado y la mentalidad emprendedora a través de nuevas prácticas de la gestión pública. En el caso de Valencia, el proyecto de ciudad neoliberal ha pivotado sobre los grandes proyectos y eventos, con la espectacular Ciudad de las Artes y de las Ciencias como mascarón de proa. Nuestra reflexión pretende vincular urbanismo neoliberal, política cultural y modelo de ciudad, utilizando como clave de bóveda el rol que el glolugar en nuestro caso la Ciudad de las Artes y de las Ciencias, tiene en el proceso. Sin embargo, frente a las políticas neoliberales del glolugar se ha ido conformando desde los barrios populares una serie de acciones socio-culturales desarrolladas por una red de asociaciones, grupos, colectivos e iniciativas culturales, que abordamos en cuarto lugar. Estas respuestas, unas más profesionales y otras más críticas con dicho modelo, ahora en crisis, proponen iniciativas culturales resistentes y alternativas.This paper discusses how the hegemony of the global place (glolugar), the paradigmatic figure of the urban neoliberal processes, has implied a certain model of cultural policy and urban development. This model has been developed in the project of City of the Arts and of the Sciences, in Valencia City. The cultural hegemony of the glolugar cannot be understood without framing it in a global trend since it is the extension of the neoliberal urbanism. In this frame, the city is conceived as a competitive entity in a global space that promotes the commoditization of urban space and the entrepreneurial attitude in the local public management. From the analysis of the City of the Arts and of the Sciences, we will investigate the links between neoliberal urbanism, cultural politics and city model. Nevertheless, we will show how the struggles against these neoliberal policies of the glolugar there has been conforming in the popular neighborhoods some socio-cultural actions, to counteract this gentrifying trend and to propose an alternative culture and urban planning

The population of SNe/SNRs in the starburst galaxy Arp 220. A self-consistent analysis of 20 years of VLBI monitoring

The nearby ultra-luminous infrared galaxy (ULIRG) Arp 220 is an excellent laboratory for studies of extreme astrophysical environments. For 20 years, Very Long Baseline Interferometry (VLBI) has been used to monitor a population of compact sources thought to be supernovae (SNe), supernova remnants (SNRs) and possibly active galactic nuclei (AGNs). Using new and archival VLBI data spanning 20 years, we obtain 23 high-resolution radio images of Arp 220 at wavelengths from 18 cm to 2 cm. From model-fitting to the images we obtain estimates of flux densities and sizes of all detected sources. We detect radio continuum emission from 97 compact sources and present flux densities and sizes for all analysed observation epochs. We find evidence for a LD-relation within Arp 220, with larger sources being less luminous. We find a compact source LF $n(L)\propto L^\beta$ with $\beta=-2.19\pm0.15$, similar to SNRs in normal galaxies. Based on simulations we argue that there are many relatively large and weak sources below our detection threshold. The observations can be explained by a mixed population of SNe and SNRs, where the former expand in a dense circumstellar medium (CSM) and the latter interact with the surrounding interstellar medium (ISM). Nine sources are likely luminous, type IIn SNe. This number of luminous SNe correspond to few percent of the total number of SNe in Arp 220 which is consistent with a total SN-rate of 4 yr$^{-1}$ as inferred from the total radio emission given a normal stellar initial mass function (IMF). Based on the fitted luminosity function, we argue that emission from all compact sources, also below our detection threshold, make up at most 20\% of the total radio emission at GHz frequencies.Comment: Accepted for publication in Astronomy and Astrophysic

Radio emission of SN1993J: the complete picture. I. Re-analysis of all the available VLBI data

We have performed a complete re-calibration and re-analysis of all the available VLBI observations of supernova SN1993J, following an homogeneous and well-defined methodology. Observations of SN1993J at 69 epochs, spanning 13 years, were performed by two teams, which used different strategies and analysis tools. The results obtained by each group are similar, but their conclusions on the supernova expansion and the shape and evolution of the emitting region differ significantly. From our analysis of the combined set of observations, we have obtained an expansion curve with unprecedented time resolution and coverage. We find that the data from both teams are compatible when analyzed with the same methodology. One expansion index ($m_3 = 0.87 \pm 0.02$) is enough to model the expansion observed at 1.7\,GHz, while two expansion indices ($m_1 = 0.933\pm0.010$ and $m_2 = 0.796\pm0.005$), separated by a break time, $t_{br} = 390\pm30$ days, are needed to model the data, at frequencies higher than 1.7\,GHz, up to day 4000 after explosion. We thus confirm the wavelength dependence of the size of the emitting region reported by one of the groups. We also find that all sizes measured at epochs later than day 4000 after explosion are systematically smaller than our model predictions. We estimate the fractional shell width ($0.31 \pm 0.02$, average of all epochs and frequencies) and the level of opacity to the radio emission by the ejecta. We find evidence of a spectral-index radial gradient in the supernova shell, which is indicative of a frequency-dependent ejecta opacity. Finally, we study the distribution and evolution of the azimuthal anisotropies (hot spots) found around the radio shell during the expansion. These anisotropies have intensities of $\sim 20$% of the mean flux density of the shell, and appear to systematically evolve during the expansion.Comment: 13 pages, 9 figures, accepted for publication in A&

On the coherence loss in phase-referenced VLBI observations

Context: Phase referencing is a standard calibration technique in radio interferometry, particularly suited for the detection of weak sources close to the sensitivity limits of the interferometers. However, effects from a changing atmosphere and inaccuracies in the correlator model may affect the phase-referenced images, leading to wrong estimates of source flux densities and positions. A systematic observational study of signal decoherence in phase referencing, and its effects in the image plane, has not been performed yet. Aims: We systematically studied how the signal coherence in Very-Long-Baseline-Interferometry (VLBI) observations is affected by a phase-reference calibration at different frequencies and for different calibrator-to-target separations. The results obtained should be of interest for a correct interpretation of many phase-referenced observations with VLBI. Methods: We observed a set of 13 strong sources (the S5 polar cap sample) at 8.4 and 15 GHz in phase-reference mode, with 32 different calibrator/target combinations spanning angular separations between 1.5 and 20.5 degrees. We obtained phase-referenced images and studied how the dynamic range and peak flux density depend on observing frequency and source separation. Results: We obtained dynamic ranges and peak flux densities of the phase-referenced images as a function of frequency and separation from the calibrator. We compared our results with models and phenomenological equations previously reported. Conclusions: The dynamic range of the phase-referenced images is strongly limited by the atmosphere at all frequencies and for all source separations. The limiting dynamic range is inversely proportional to the sine of the calibrator-to-target separation. We also find that the peak flux densities, relative to those obtained with the self-calibrated images, decrease with source separation.Comment: 5 pages, 3 figures. Submitted to A&A on 5.02.2010; accepted on 11.03.2010

Automatic image characterization of psoriasis lesions

Psoriasis is a chronic skin disease that affects 125 million people worldwide and, par-ticularly, 2% of the Spanish population, characterized by the appearance of skin lesions due to a growth of the epidermis that is seven times larger than usual. Its diagnosis and monitoring are based on the use of methodologies for measuring the severity and extent of these spots, and this includes a large subjective component. For this reason, this paper presents an automatic method for characterizing psoriasis images that is divided into four parts: image preparation or pre-processing, feature extraction, classification of the lesions, and the obtaining of parameters. The methodology proposed in this work covers different digital-image processing techniques, namely, marker-based image delimitation, hair removal, nipple detection, lesion contour detection, areal-measurement-based lesion classification, as well as lesion characterization by means of red and white intensity. The results obtained were also endorsed by a professional dermatologist. This methodology provides professionals with a common software tool for monitoring the different existing typologies, which proved satisfactory in the cases analyzed for a set of 20 images corresponding to different types of lesions

Exploring long-term variability of Nephrops norvegicus population in the Porcupine Bank (SW Ireland)

PresentationNephrops norvegicus is a commercial species of the bottom fisheries in European western waters which yield has long-term variability. Their distribution is linked to suitable habitats of muddy sediment in which adults construct burrows but the influence of environmental factors on the populations was poorly investigated. Variability in the catch per unit effort (CPUE) of Nephrops norvegicus from Porcupine Bank (Southwest of Ireland) was explored using a time series approach. The CPUE time series (1979-2005) exhibited a seasonal pattern. The seasonal decomposition of the CPUE shows a declining trend in the trend and cycle component from 1982 onwards. ARMA univariate and dynamic regression models were fitted to the CPUE time series. Population (proportion of males, proportion of ovigerous females and recruits) and North Atlantic Oscillation index were tested at different lags to investigate possible factors related to the yield fluctuations