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  • Oxford University Press  (185)
  • American Physical Society (APS)  (53)
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  • 1
    Publication Date: 2015-06-05
    Description: We present a kinematical study of 29 spiral galaxies included in the Spitzer Survey of Stellar Structure in Galaxies, using Hα Fabry–Perot (FP) data obtained with the Galaxy Hα Fabry–Perot System instrument at the William Herschel Telescope in La Palma, complemented with images in the R band and in Hα. The primary goal is to study the evolution and properties of the main structural components of galaxies through the kinematical analysis of the FP data, complemented with studies of morphology, star formation and mass distribution. In this paper we describe how the FP data have been obtained, processed and analysed. We present the resulting moment maps, rotation curves, velocity model maps and residual maps. Images are available in fits format through the NASA/IPAC Extragalactic Database and the Centre de Données Stellaires. With these data products we study the non-circular motions, in particular those found along the bars and spiral arms. The data indicate that the amplitude of the non-circular motions created by the bar does not correlate with the bar strength indicators. The amplitude of those non-circular motions in the spiral arms does not correlate with either arm class or star formation rate along the spiral arms. This implies that the presence and the magnitude of the streaming motions in the arms is a local phenomenon.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 2
    Publication Date: 2015-11-20
    Description: The postfledging dependence period (PFDP) is a crucial stage in the development of altricial birds. This period is regulated by parental investment, in terms of food provisioning and protection, and the demands of young associated with their development and physical condition. We examine the relative role of parental investment, food provisioning, and offspring decisions on the PFDP regulation in the Spanish imperial eagle ( Aquila adalberti ) by comparing the PFDP timing among young from non-manipulated territories, food supplemented territories, and birds translocated by hacking methods in the absence of adults and with ad libitum food supply. We found that extra food homogenized the nutritional condition of young and reduced the length of the first stage of PFDP, which is related to flight development and thus dependent on body condition. However, hacked birds did not reduce this stage despite ad libitum food, likely due to the lack of parental stimulus to develop advanced flights. Although the presence of adults might accelerate young becoming independent, hacked birds did not extend significantly the whole PFDP and all birds eventually started dispersal. Thereby, the PFDP regulation was primarily under offspring control, and modulated secondarily by parental effects independently of food provisioning and laying date. The length of this period seems to be constrained mainly by the inherent benefits of early dispersal on ultimate fitness in accordance with ontogenic hypotheses. In addition, hacking was shown to be an effective translocation method when properly used, without negative drawbacks for young development during the PFDP.
    Print ISSN: 1045-2249
    Electronic ISSN: 1465-7279
    Topics: Biology
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  • 3
    Publication Date: 2015-05-27
    Description: Motivation: With the advent of meta-‘omics’ data, the use of metabolic networks for the functional analysis of microbial communities became possible. However, while network-based methods are widely developed for single organisms, their application to bacterial communities is currently limited. Results: Herein, we provide a novel, context-specific reconstruction procedure based on metaproteomic and taxonomic data. Without previous knowledge of a high-quality, genome-scale metabolic networks for each different member in a bacterial community, we propose a meta-network approach, where the expression levels and taxonomic assignments of proteins are used as the most relevant clues for inferring an active set of reactions. Our approach was applied to draft the context-specific metabolic networks of two different naphthalene-enriched communities derived from an anthropogenically influenced, polyaromatic hydrocarbon contaminated soil, with (CN2) or without (CN1) bio-stimulation. We were able to capture the overall functional differences between the two conditions at the metabolic level and predict an important activity for the fluorobenzoate degradation pathway in CN1 and for geraniol metabolism in CN2. Experimental validation was conducted, and good agreement with our computational predictions was observed. We also hypothesize different pathway organizations at the organismal level, which is relevant to disentangle the role of each member in the communities. The approach presented here can be easily transferred to the analysis of genomic, transcriptomic and metabolomic data. Contact: fplanes@ceit.es or mferrer@icp.csic.es Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
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  • 4
    Publication Date: 2016-07-29
    Description: In cosmological N -body simulations, the representation of dark matter as discrete ‘macroparticles’ suppresses the growth of structure, such that simulations no longer reproduce linear theory on small scales near k Nyquist . Marcos et al. demonstrate that this is due to sparse sampling of modes near k Nyquist and that the often-assumed continuum growing modes are not proper growing modes of the particle system. We develop initial conditions (ICs) that respect the particle linear theory growing modes and then rescale the mode amplitudes to account for growth suppression. These ICs also allow us to take advantage of our very accurate N -body code abacus to implement second-order Lagrangian perturbation theory (2LPT) in configuration space. The combination of 2LPT and rescaling improves the accuracy of the late-time power spectra, halo mass functions, and halo clustering. In particular, we achieve 1 per cent accuracy in the power spectrum down to k Nyquist , versus k Nyquist /4 without rescaling or k Nyquist /13 without 2LPT, relative to an oversampled reference simulation. We anticipate that our 2LPT will be useful for large simulations where fast Fourier transforms are expensive and that rescaling will be useful for suites of medium-resolution simulations used in cosmic emulators and galaxy survey mock catalogues. Code to generate ICs is available at https://github.com/lgarrison/zeldovich-PLT .
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 5
    Publication Date: 2013-09-20
    Description: Author(s): Laleh Sadeghian, Francesc Ferrer, and Clifford M. Will The cold dark matter at the center of a galaxy will be redistributed by the presence of a massive black hole. The redistribution may be determined using an approach pioneered by Gondolo and Silk: begin with a model distribution function for the dark matter, and “grow” the black hole adiabatically, h... [Phys. Rev. D 88, 063522] Published Thu Sep 19, 2013
    Keywords: Astrophysics & Cosmology
    Print ISSN: 0556-2821
    Electronic ISSN: 1089-4918
    Topics: Physics
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  • 6
    Publication Date: 2013-10-02
    Description: The advances in the digital world (e.g. the Internet, Communications, etc.) are closing the gap between consumers and providers, in both Business to Consumer and Business to Business environments. Through the Internet, providers can offer their products directly to consumers, which increase their choices and allow them to contract a set of different services/products from different providers. But sometimes the consumer needs an all-or-nothing exchange with these providers: an atomic exchange. The consumer has negotiated/obtained a set of conditions that are only met if she acquires all the services/products. Thus, we need an Atomic Multi-Two-Party contract signing protocol. Even though digital signature of contracts is a topic that has been widely studied, it lacks a solution when applied to Atomic Multi-Two-Party scenarios. Here, we propose the first solution to solve this problem.
    Print ISSN: 0010-4620
    Electronic ISSN: 1460-2067
    Topics: Computer Science
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  • 7
    Publication Date: 2015-05-06
    Description: Author(s): E. J. Ferrer, V. de la Incera, D. Manreza Paret, A. Pérez Martínez, and A. Sanchez We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EOS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields ( e B 〉 m 2 ), the AMM is found from the one-loop fermion self-energy. In contr... [Phys. Rev. D 91, 085041] Published Mon Apr 27, 2015
    Keywords: Field Theory, Formal Particle Theory
    Print ISSN: 0556-2821
    Electronic ISSN: 1089-4918
    Topics: Physics
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  • 8
    Publication Date: 2015-05-08
    Description: Using multiwavelength kinematic and photometric data we have analysed the gaseous and stellar properties of a previously uncharacterized low-mass star-forming companion and newly discovered stellar stream seen projected against the edge-on spiral galaxy NGC 7241. The companion object was identified serendipitously as an offset velocity component in H α Fabry–Perot observations along the line of sight to NGC 7241, and is most prominent visually in UV and blue wavelengths. Its occulting position with respect to NGC 7241 allows measurement of its dust extinction properties which are then combined with photometric spectral energy distribution fitting and long-slit spectroscopy to study star formation (SF) in this gas-rich accreting dwarf galaxy. The dynamical properties of the stream and companion suggest that they may likely be remnants of the same low-mass progenitor dwarf galaxy which is being disrupted during its accretion on to NGC 7241 – with the companion's recent SF triggered during its passage with the disc of NGC 7241. This is supported by the companion's metallicity and SF rates, the asymmetric SF in the disc of NGC 7241, as well as the coincident velocity of the extraplanar H i filament and the star-forming companion. In contrast, mass estimates from dynamical modelling of NGC 7241 rule out an interaction between NGC 7241 and UGC 11964 (the other large spiral galaxy in the group) within the last ~3 Gyr – making such an interaction a poor candidate for inducing the recent SF in the system. Together, the data for this system offer a window into how SF proceeds in low-mass mergers.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 9
    Publication Date: 2015-05-16
    Description: Non-vanishing parity-odd correlators of gamma-ray arrival directions observed by Fermi -LAT indicate the existence of a helical intergalactic magnetic field with strength B ~ 10 –14  G on ~10 Mpc scales. We successfully test this hypothesis using more stringent cuts of the data, Monte Carlo simulations with Fermi -LAT time exposure information, separate analyses for the Northern and Southern galactic hemispheres, and confirm predictions made in Tashiro & Vachaspati. With some further technical assumptions, we show how to reconstruct the magnetic helicity spectrum from the parity-odd correlators.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 10
    Publication Date: 2015-03-27
    Description: Electronic multicoupons are the digital version of paper-based booklet of coupons, which allow a customer to obtain goods or services from a merchant typically with discounts or gifts. In this paper, we propose a multicoupon scheme for multi-merchant environments that enhances the security and the efficiency as regards the previous solution that deals with this kind of scenario. On one hand, our scheme meets basic security requirements (unforgeability, reuse detection), but also unsplittability. This fact will help to increase the trust on the part of merchants. On the other hand, we focus on achieving a high degree of privacy for customers (anonymity, unlinkability, confidentiality) that will contribute to gaining the trust of the involved customers. Moreover, we provide measures to protect honest parties from dishonest participants, keeping in mind the scalability and efficiency of the multicoupon scheme, to attract customers and merchants. In addition, we show by implementation that our proposal outperforms previous solutions of this kind.
    Print ISSN: 0010-4620
    Electronic ISSN: 1460-2067
    Topics: Computer Science
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