18,355 research outputs found

    DGSAT: Dwarf Galaxy Survey with Amateur Telescopes II. A catalogue of isolated nearby edge-on disk galaxies and the discovery of new low surface brightness systems

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    The connection between the bulge mass or bulge luminosity in disk galaxies and the number, spatial and phase space distribution of associated dwarf galaxies is a discriminator between cosmological simulations related to galaxy formation in cold dark matter and generalized gravity models. Here, a nearby sample of isolated Milky Way class edge-on galaxies is introduced, to facilitate observational campaigns to detect the associated families of dwarf galaxies at low surface brightness. Three galaxy pairs with at least one of the targets being edge-on are also introduced. About 60% of the catalogued isolated galaxies contain bulges of different size, while the remaining objects appear to be bulge-less. Deep images of NGC 3669 (small bulge, with NGC 3625 at the edge of the image) and NGC 7814 (prominent bulge), obtained with a 0.4-m aperture, are also presented, resulting in the discovery of two new dwarf galaxy candidates, NGC3669-DGSAT-3 and NGC7814-DGSAT-7. Eleven additional low surface brightness galaxies are identified, previously notified with low quality measurement flags in the Sloan Digital Sky Survey (SDSS). Integrated magnitudes, surface brightnesses, effective radii, Sersic indices, axis ratios, and projected distances to their putative major hosts are displayed. At least one of the galaxies, NGC3625-DGSAT-4, belongs with a surface brightness of approximately 26 mag per arcsec^2 and effective radius >1.5 kpc to the class of ultra-diffuse galaxies (UDGs). NGC3669-DGSAT-3, the galaxy with lowest surface brightness in our sample, may also be an UDG.Comment: 12 pages including 6 figures, 4 tables, a brief appendix, accepted for publication in Astronomy & Astrophysics (A&A). Paper slightly modified after A&A language editing, updating very few references and correcting a small typo at the start of the Appendi

    On the generalized Feng-Rao numbers of numerical semigroups generated by intervals

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    We give some general results concerning the computation of the generalized Feng-Rao numbers of numerical semigroups. In the case of a numerical semigroup generated by an interval, a formula for the rthr^{th} Feng-Rao number is obtained.Comment: 23 pages, 6 figure

    ¿Existe alguna relación entre la capacidad de movimiento funcional y el estado ponderal? Un estudio en escolares españoles

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    Indexación: Scopus.Background: to examine relations between functional movement patterns and weight status in Spanish primary school children and to determine the differences between sexes. Methods: three hundred and thirty-three, 6-13 years old children (164 boys and 169 girls), participated in this study. The main outcome measures were the body mass index (BMI) and the Functional Movement Screen™ (FMS). Children were classified as normal weight (NW), overweight (OV) or obese (OB) according to international cut-offs. Results: total FMS score was negatively correlated with BMI (p < 0.001). FMS score was different between children from NW, OV and OB groups (p = 0.001), lower with the increased BMI (p < 0.001 between all groups). Significant differences (p < 0.05) between NW, OV and OB were found in deep squat, hurdle step, in-line lunge, shoulder mobility, straight leg-raise and push-up tests. As for the sex differences, girls obtained higher scores (p < 0.05) in in-line lunge, shoulder mobility and straight leg-raise, whereas boys did it in push-up (p = 0.044) test. Conclusions: these results confirm that total FMS score significantly and inversely correlates with BMI in a group of 333 school-age children. As for the sex differences, girls outperform boys in movements requiring flexibility and balance, whilst boys outperform girls in tests where muscular strength is required. © 2018 SENPE and Arán Ediciones S.L.Introducción: examinar la relación entre los patrones de movimiento funcional y el estado ponderal en escolares españoles, determinando también la infl uencia de la variable sexo. Métodos: trescientos treinta y tres niños de 6-13 años de edad (164 niños y 169 niñas), participaron voluntariamente en este estudio. Las variables objeto de estudio fueron el índice de masa corporal (IMC) y la batería de test Functional Movement ScreenTM (FMS). Los niños fueron clasifi cados como normopeso (NW), sobrepeso (OV) y obesos (OB) de acuerdo con los puntos de corte internacionales. Resultados: la puntuación total en el FMS correlacionó de forma negativa y signifi cativa con el IMC (p < 0,001). La puntuación en FMS fue diferente entre las categorías de peso (p = 0,001), hallando un peor rendimiento en FMS conforme aumenta el IMC (p < 0,001 entre todos los grupos). Se hallaron diferencias signifi cativas (p < 0,05) entre NW, OV y OB en los test de deep squat, hurdle step, in-line lunge, shoulder mobility, straight leg-raise and push-up. En cuanto a las diferencias por sexo, las chicas obtuvieron puntuaciones más altas en FMS (p < 0,05) en los test in-line lunge, shoulder mobility and straight leg-raise; mientras los chicos obtuvieron puntuaciones superiores en el test de push-up (p = 0,044). Conclusiones: los resultados confi rman que la puntuación total en el FMS correlaciona signifi cativa y negativamente con el IMC en este grupo de 333 escolares. En cuanto a la infl uencia del sexo, las chicas obtuvieron mayor puntuación que los chicos en los test que requerían fl exibilidad y equilibrio, mientras los chicos fueron superiores en los test en los que predominaba la fuerza muscular.https://www.nutricionhospitalaria.org/index.php/articles/01670/show#

    Probing O-enrichment in C-rich dust planetary nebulae

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    The abundance of O in planetary nebulae (PNe) has been historically used as a metallicity indicator of the interstellar medium (ISM) where they originated; e.g., it has been widely used to study metallicity gradients in our Galaxy and beyond. However, clear observational evidence for O self enrichment in low-metallicity Galactic PNe with C-rich dust has been recently reported. Here we report asymptotic giant branch (AGB) nucleosynthesis predictions for the abundances of the CNO elements and helium in the metallicity range Zsun/4 < Z < 2Zsun. Our AGB models, with diffusive overshooting from all the convective borders, predict that O is overproduced in low-Z low-mass (~1-3 Msun) AGB stars and nicely reproduce the recent O overabundances observed in C-rich dust PNe. This confirms that O is not always a good proxy of the original ISM metallicity and another chemical elements such as Cl or Ar should be used instead. The production of oxygen by low-mass stars should be thus considered in galactic-evolution models.Comment: Accepted for publication in MNRAS Letters (5 pages, 1 figure, and 1 table

    Divergences in Kaluza-Klein Models and their String Regularization

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    Effective field theories with (large) extra dimensions are studied within a physical regularization scheme provided by string theory. Explicit string calculations then allow us to consistently analyze the ultraviolet sensitivity of Kaluza--Klein theories in the presence or absence of low energy supersymmetry.Comment: 50 pages, LaTe

    Galactic planetary nebulae with precise nebular abundances as a tool to understand the evolution of asymptotic giant branch stars

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    We present nucleosynthesis predictions (HeCNOCl) from asymptotic giant branch (AGB) models, with diffusive overshooting from all the convective borders, in the metallicity range Z/4 < Z < 2Zsun. They are compared to recent precise nebular abundances in a sample of Galactic planetary nebulae (PNe) that is divided among double-dust chemistry (DC) and oxygen-dust chemistry (OC) according to the infrared dust features. Unlike the similar subsample of Galactic carbon-dust chemistry PNe recently analysed by us, here the individual abundance errors, the higher metallicity spread, and the uncertain dust types/subtypes in some PNe do not allow a clear determination of the AGB progenitor masses (and formation epochs) for both PNe samples; the comparison is thus more focussed on a object-by-object basis. The lowest metallicity OC PNe evolve from low-mass (~1 Msun) O-rich AGBs, while the higher metallicity ones (all with uncertain dust classifications) display a chemical pattern similar to the DC PNe. In agreement with recent literature, the DC PNe mostly descend from high-mass (M > 3.5 Msun) solar/supersolar metallicity AGBs that experience hot bottom burning (HBB), but other formation channels in low-mass AGBs like extra mixing, stellar rotation, binary interaction, or He pre-enrichment cannot be disregarded until more accurate C/O ratios would be obtained. Two objects among the DC PNe show the imprint of advanced CNO processing and deep second dredge-up, suggesting progenitors masses close to the limit to evolve as core collapse supernovae (above 6 Msun). Their actual C/O ratio, if confirmed, indicate contamination from the third dredge-up, rejecting the hypothesis that the chemical composition of such high-metallicity massive AGBs is modified exclusively by HBB.Comment: Accepted for publication in MNRAS (11 pages, 3 figures, and 2 tables

    Dispatcher3 D1.1 - Technical resources and problem definition

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    This deliverable starts with the proposal of Dispatcher3 and incorporates the development produced during the first five months of the project: activities on different workpackages, interaction with Topic Manager and Project Officer, and input received during the first Advisory Board meeting and follow up consultations. This deliverable presents the definition of Dispatcher3 concept and methodology. It includes the high level the requirements of the prototype, preliminary data requirements, preliminary technical infrastructure requirements, preliminary data processing and analytic techniques identification and a preliminary definition of scenarios. The deliverable aims at defining the view of the consortium on the project at these early stages, incorporating the feedback obtained from the Advisory Board and highlighting the further activities required to define some of the aspects of the project

    Homological Error Correction: Classical and Quantum Codes

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    We prove several theorems characterizing the existence of homological error correction codes both classically and quantumly. Not every classical code is homological, but we find a family of classical homological codes saturating the Hamming bound. In the quantum case, we show that for non-orientable surfaces it is impossible to construct homological codes based on qudits of dimension D>2D>2, while for orientable surfaces with boundaries it is possible to construct them for arbitrary dimension DD. We give a method to obtain planar homological codes based on the construction of quantum codes on compact surfaces without boundaries. We show how the original Shor's 9-qubit code can be visualized as a homological quantum code. We study the problem of constructing quantum codes with optimal encoding rate. In the particular case of toric codes we construct an optimal family and give an explicit proof of its optimality. For homological quantum codes on surfaces of arbitrary genus we also construct a family of codes asymptotically attaining the maximum possible encoding rate. We provide the tools of homology group theory for graphs embedded on surfaces in a self-contained manner.Comment: Revtex4 fil

    Quantum simulation of Anderson and Kondo lattices with superconducting qubits

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    We introduce a mapping between a variety of superconducting circuits and a family of Hamiltonians describing localized magnetic impurities interacting with conduction bands. This includes the Anderson model, the single impurity one- and two-channel Kondo problem, as well as the 1D Kondo lattice. We compare the requirements for performing quantum simulations using the proposed circuits to those of universal quantum computation with superconducting qubits, singling out the specific challenges that will have to be addressed.Comment: Longer versio
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