5,830 research outputs found

    An Expanding HI Photodissociated Region Associated with the Compact HII Region G213.880-11.837 in the GGD 14 Complex

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    We present high angular and spectral resolution HI 21~cm line observations toward the cometary-shaped compact HII region G213.880-11.837 in the GGD~14 complex.The kinematics and morphology of the photodissociated region, traced by the HI line emission, reveal that the neutral gas is part of an expanding flow. The kinematics of the HI gas along the major axis of G213.880-11.837 shows that the emission is very extended toward the SE direction, reaching LSR radial velocities in the tail of about 14 km/s. The ambient LSR radial velocity of the molecular gas is 11.5 km/s, which suggests a champagne flow of the HI gas. This is the second (after G111.61+0.37) cometary HII/HI region known.Comment: Accepted for publication in the Astronomical Journal (10 pages, 4 figures, 1 table

    Matrix Big Brunch

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    Following the holographic description of linear dilaton null Cosmologies with a Big Bang in terms of Matrix String Theory put forward by Craps, Sethi and Verlinde, we propose an extended background describing a Universe including both Big Bang and Big Crunch singularities. This belongs to a class of exact string backgrounds and is perturbative in the string coupling far away from the singularities, both of which can be resolved using Matrix String Theory. We provide a simple theory capable of describing the complete evolution of this closed Universe.Comment: 15 pages, no figures. References adde

    Quantum Phase Transitions detected by a local probe using Time Correlations and Violations of Leggett-Garg Inequalities

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    In the present paper we introduce a way of identifying quantum phase transitions of many-body systems by means of local time correlations and Leggett-Garg inequalities. This procedure allows to experimentally determine the quantum critical points not only of finite-order transitions but also those of infinite order, as the Kosterlitz-Thouless transition that is not always easy to detect with current methods. By means of simple analytical arguments for a general spin-1/21 / 2 Hamiltonian, and matrix product simulations of one-dimensional XXZX X Z and anisotropic XYX Y models, we argue that finite-order quantum phase transitions can be determined by singularities of the time correlations or their derivatives at criticality. The same features are exhibited by corresponding Leggett-Garg functions, which noticeably indicate violation of the Leggett-Garg inequalities for early times and all the Hamiltonian parameters considered. In addition, we find that the infinite-order transition of the XXZX X Z model at the isotropic point can be revealed by the maximal violation of the Leggett-Garg inequalities. We thus show that quantum phase transitions can be identified by purely local measurements, and that many-body systems constitute important candidates to observe experimentally the violation of Leggett-Garg inequalities.Comment: Minor changes, 11 pages, 11 figures. Final version published in Phys. Rev.

    Una revista de presente que mira al futuro

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    FARMACÉUTICOS COMUNITARIOS da un nuevo paso adelante. Desde su nacimiento en 2009 con su cabecera actual y como heredera de e-farmacéutico comunitario, la revista de ­SEFAC ha experimentado una continua progresión en busca de dos objetivos claros: por un lado, promover, fomentar y consolidar la investigación en farmacia comunitaria en España acercando también a los socios asuntos profesionales relevantes, y, por otro, convertirse en la revista científica de referencia en la publicación de artículos y trabajos de investigación realizados por farmacéuticos comunitarios o de interés para nuestro colectivo.FARMACÉUTICOS COMUNITARIOS da un nuevo paso adelante. Desde su nacimiento en 2009 con su cabecera actual y como heredera de e-farmacéutico comunitario, la revista de ­SEFAC ha experimentado una continua progresión en busca de dos objetivos claros: por un lado, promover, fomentar y consolidar la investigación en farmacia comunitaria en España acercando también a los socios asuntos profesionales relevantes, y, por otro, convertirse en la revista científica de referencia en la publicación de artículos y trabajos de investigación realizados por farmacéuticos comunitarios o de interés para nuestro colectivo

    The missing atom as a source of carbon magnetism

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    Atomic vacancies have a strong impact in the mechanical, electronic and magnetic properties of graphene-like materials. By artificially generating isolated vacancies on a graphite surface and measuring their local density of states on the atomic scale, we have shown how single vacancies modify the electronic properties of this graphene-like system. Our scanning tunneling microscopy experiments, complemented by tight binding calculations, reveal the presence of a sharp electronic resonance at the Fermi energy around each single graphite vacancy, which can be associated with the formation of local magnetic moments and implies a dramatic reduction of the charge carriers' mobility. While vacancies in single layer graphene naturally lead to magnetic couplings of arbitrary sign, our results show the possibility of inducing a macroscopic ferrimagnetic state in multilayered graphene samples just by randomly removing single C atoms.Comment: Accepted for publication in Physical Review Letter

    Intraspecific genetic variation in complex assemblages from mitochondrial metagenomics: comparison with DNA barcodes

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    Metagenomic shotgun sequencing, using Illumina technology, and de novo genome assembly of mixed field-collected amples of invertebrates readily produce mitochondrial genome sequences, allowing rapid identification and quantification of species diversity. However, intraspecific genetic variability present in the specimen pools is lost during mitogenome assembly, which limits the utility of ‘mitochondrial metagenomics’ for studies of population diversity. 2. Using 10 natural communities (>2600 individuals) of leaf beetles (Chrysomelidae), DNA variation in the mitochondrial cox1-5’ ‘barcode’ was compared for Sanger sequenced individuals and Illumina shotgun sequenced specimen pools. 3. Generally, only a single mitochondrial contig was assembled per species, even in the presence of intraspecific variation. Ignoring ambiguity from the use of two different assemblers, the cox1 barcode regions from these assemblies were exact nucleotide matches of a Sanger sequenced barcode in 90.7% of cases, which dropped to 76.0% in assemblies from samples with large intra and interspecific variability. Nucleotide differences between barcodes from both data types were almost exclusively in synonymous 3rd codon position, although the number of affected sites was very low, and the greatest discrepancies were correlated with poor quality of Sanger sequences. 4. Unassembled shotgun reads were also used to score single nucleotide polymorphisms and to calculate intraspecific nucleotide diversity (pi) for all available populations at each site. These values correlated with Sanger sequenced cox1 variation but were significantly higher. 5. Overall, the assemblage-focused shotgun sequencing of pooled samples produced nucleotide variation data comparable to the well-established specimen-focused Sanger approach. The findings thus extend the application of mitochondrial metagenomics of complex biodiversity samples to the estimation of diversity below the species level

    Estudio de la marcha en la infancia

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    El análisis de la marcha se ha visto reforzado por la aparición de sistemas de invetigación de nueva tecnología como son las plataformas de fuerzas monitorizadas que permiten estudiar, con alta precisión, el desarrollo cinético y en parte cinemático de la marcha. Con este sistema hemos estudiado el paso de 62 niños de 5 y 6 años de edad, para determinar los valores de normalidad de los parámetros temporoespaciales y las magnitudes de las fuerzas de reacción pie-suelo en los tres ejes de plano espaciales. Hemos encontrado diferencias estadísticamente significativas entre estas edades para la longitud de paso, tiempo de doble apoyo y la mayoría de las fuerzas de reacción del suelo, indicando una evolución de la marcha en este periodo

    Computer vision techniques for forest fire perception

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    This paper presents computer vision techniques for forest fire perception involving measurement of forest fire properties (fire front, flame height, flame inclination angle, fire base width) required for the implementation of advanced forest fire-fighting strategies. The system computes a 3D perception model of the fire and could also be used for visualizing the fire evolution in remote computer systems. The presented system integrates the processing of images from visual and infrared cameras. It applies sensor fusion techniques involving also telemetry sensors, and GPS. The paper also includes some results of forest fire experiments.European Commission EVG1-CT-2001-00043European Commission IST-2001-34304Ministerio de Educación y Ciencia DPI2005-0229
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