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Fernandez-Del-castillo E.,Institute Fisica Of Cantabria
Computing and Informatics | Year: 2012

The current middleware stacks provide varying support for the Message Passing Interface (MPI) programming paradigm. Users face a complex and heterogeneous environment where too many low level details have to be specified to execute even the simplest parallel jobs. MPI-Start is a tool that provides an interoperable MPI execution framework across the different middleware implementations to abstract the user interfaces from the underlying middleware and to allow users to execute parallel applications in a uniform way, thus bridging the gap between HPC and HTC. In this work we present the latest developments in MPI-Start and how it can be integrated in the different middleware stacks available as part of EMI, providing a unified user experience for MPI jobs.

Torres D.F.,Catalan Institution for Research and Advanced Studies | Torres D.F.,Institute Of Ciencies Of Lespai Ieec Csic | Marrero A.Y.R.,Institute Fisica Of Cantabria | De Cea Del Pozo E.,Institute Of Ciencies Of Lespai Ieec Csic
Monthly Notices of the Royal Astronomical Society | Year: 2010

We have recently interpreted the source MAGIC J0616+225 as a result of delayed TeV emission of cosmic rays diffusing from IC 443 and interacting with a cloud in the foreground of the remnant. This model was used to make predictions for future observations, especially those to be made with the Fermi satellite. Just recently, AGILE, Fermi and Very Energetic Radiation Imaging Telescope Array System (VERITAS) have released new results of their observations of IC 443. In this paper, we compare them with the predictions of our model, exploring the GeV to TeV connection in this region of space. We use Fermi data to consider the possibility of constraining the cosmic ray diffusion features of the environment. We analyse the cosmic ray distributions, their interactions and a possible detection of the supernova remnant environment in the neutrino channel. © 2010 The Authors. Journal compilation © 2010 RAS.

Hernan-Caballero A.,Institute Fisica Of Cantabria
Monthly Notices of the Royal Astronomical Society | Year: 2012

Obtaining accurate redshifts from mid-infrared (MIR) low-resolution (R ~ 100) spectroscopy is challenging because the wavelength resolution is too low to detect narrow lines in most cases. Yet, the number of degrees of freedom and diversity of spectral features are too high for regular spectral energy distribution (SED) fitting techniques to be convenient. Here we present a new SED-fitting-based routine for redshift determination that is optimized for MIR low-resolution spectroscopy. Its flexible template scaling increases the sensitivity to slope changes and small-scale features in the spectrum, while a new selection algorithm called maximum combined pseudo-likelihood (MCPL) provides increased accuracy and a lower number of outliers compared to the standard maximum-likelihood (ML) approach. Unlike ML approach, the MCPL approach searches for local (instead of absolute) maxima of a 'pseudo-likelihood' (PL) function, and combines results obtained for all the templates in the library to weed out spurious redshift solutions. The capabilities of the MCPL approach are demonstrated by comparing its redshift estimates to those of the regular ML approach and to the optical spectroscopic redshifts of a sample of 491 Spitzer/Infrared Spectrograph spectra from extragalactic sources at 0 < z < 3.7. The MCPL approach achieves a redshift accuracy Δ(z)/(1 + z) < 0.005 for 78 per cent of the galaxies in the sample compared to 68 per cent for the ML approach. The rate of outliers [Δ(z)/(1 + z) > 0.02] is 14 per cent for the MCPL approach and 22 per cent for the ML approach. χ 2 values for ML solutions are found to correlate with the signal-to-noise ratio of the spectra, but not with redshift accuracy. By contrast, the peak value of the normalized combined PL (γ) is found to provide a good indication on the reliability of the MCPL solution for individual sources. The accuracy and reliability of the redshifts depend strongly on the MIR SED. Sources with significant polycyclic aromatic hydrocarbon emission obtain much better results compared to sources dominated by active galactic nucleus continua. Nevertheless, for a given γ the frequency of accurate solutions and outliers is largely independent of their SED type. This reliability indicator for MCPL solutions allows to select subsamples with highly reliable redshifts. In particular, a γ > 0.15 threshold retains 79 per cent of the sources with Δ(z)/(1 + z) < 0.005 while reducing the outlier rate to 3.8 per cent. © 2012 The Author Monthly Notices of the Royal Astronomical Society. © 2012 RAS.

Rodriguez M.A.,Institute Fisica Of Cantabria
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

The standard spectral scaling, S(f)∼1/fβ, has been traditionally used as a correlation measure characterizing the dynamical behavior of time series. The ubiquity of 1/f and 1/f2 spectra in many processes certainly suggests the existence of universal mechanisms, but also gives rise to the suspicion that some important features are not included in this scaling. In this paper we argue that a complete spectral scaling, including as a main variable the size of the series, S(f,T)∼Tη/fβ, which is usually considered irrelevant, gives an insight into this problem. Using synthetically generated series we show that, in general, the scaling exponent β is too generic, while the exponent associated with the size, η, gives a more specific information. Hence, we propose the use of both exponents in a scheme to classify series into different universality classes. In this way many of the processes appearing in the literature could be better identified, and much of the ambiguity that surrounds the standard spectral scaling could be clarified. © 2014 American Physical Society.

Frias M.D.,University of Cantabria | Minguez R.,University of Cantabria | Gutierrez J.M.,Institute Fisica Of Cantabria | Mendez F.J.,University of Cantabria
Climatic Change | Year: 2012

This paper analyzes changes of maximum temperatures in Europe, which are evaluated using two state-of-the-art regional climate models from the EU ENSEMBLES project. Extremes are expressed in terms of return values using a time-dependent generalized extreme value (GEV) model fitted to monthly maxima. Unlike the standard GEV method, this approach allows analyzing return periods at different time scales (monthly, seasonal, annual, etc). The study focuses on the end of the 20th century (1961-2000), used as a calibration/validation period, and assesses the changes projected for the period 2061-2100 considering the A1B emission scenario. The performance of the regional models is evaluated for each season of the calibration period against the high-resolution gridded E-OBS dataset, showing a similar South-North gradient with larger values over the Mediterranean basin. The inter-RCM changes in the bias pattern with respect to the E-OBS are larger than the bias resulting from a change in the boundary conditions from ERA-40 to ECHAM5 20c3m. The maximum temperature response to increased green house gases, as projected by the A1B scenario, is consistent for both RCMs. Under that scenario, results indicate that the increments for extremes (e. g. 40-year return values) will be two or three times higher than those for the mean seasonal temperatures, particularly during Spring and Summer in Southern Europe. © 2011 Springer Science+Business Media B.V.

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