1,507 research outputs found

    El yacimiento de vertebrados de cortes de Baza I (Depresión de Guadix-Baza). Nota preliminar

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    En el presente trabajo se estudia un yacimiento de micromamíferos en la Depresión de Guadix-Baza. La fauna estudiada permite datar la zona de Saint Vallier. Se señalan asimismo niveles marinos cuaternarios a 680 m de altura

    El yacimiento de vertebrados de cortes de Baza I (Depresión de Guadix-Baza). Nota preliminar

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    En el presente trabajo se estudia un yacimiento de micromamíferos en la Depresión de Guadix-Baza. La fauna estudiada permite datar la zona de Saint Vallier. Se señalan asimismo niveles marinos cuaternarios a 680 m de altura

    Orbital characterization of superbolides observed from space: dynamical association with near-Earth objects, meteoroid streams and identification of hyperbolic meteoroids

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    There is an unceasing incoming flux of extraterrestrial materials reaching the Earth's atmosphere. Some of these objects produce luminous columns when they ablate during the hypersonic encounter with air molecules. A few fireballs occur each year bright enough to be detected from space. The source of these events is still a matter of debate, but it is generally accepted that they are of sporadic origin. We studied the NASA-JPL Center for NEOs Studies (CNEOS) fireball database to infer the dynamic origin of large bolides produced by meter-sized projectiles that impacted our planet. These likely meteorite-dropping events were recorded by the US Government satellite sensors. We estimated the false-positive rate and analyzed the time evolution of multiple orbit dissimilarity criteria concerning potential associations with near-Earth objects and meteoroid streams. We found that at least 16% of the large bolides could be associated with meteoroid streams, about 4% are likely associated with near-Earth asteroids, and 4% may be linked to near-Earth comets. This implies that a significant fraction of meter-sized impactors producing large bolides may have an asteroidal or cometary origin. In addition, we found at least three bolides having hyperbolic orbits with high tensile strength values. Meter-sized meteoroids of interstellar origin could be more common than previously thought, representing about 1% of the flux of large bolides. The inferred bulk physical properties suggest that the interstellar medium could bias these projectiles towards high strength rocks with the ability to survive prolonged exposure to the harsh interstellar space conditions.Comment: Accepted for publication in The Astronomical Journal (AAS38905R1

    A photometric monitoring of bright high-amplitude delta Scuti stars. II. Period updates for seven stars

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    We present new photometric data for seven high-amplitude delta Scuti stars. The observations were acquired between 1996 and 2002, mostly in the Johnson photometric system. For one star (GW UMa), our observations are the first since the discovery of its pulsational nature from the Hipparcos data.The primary goal of this project was to update our knowledge on the period variations of the target stars. For this, we have collected all available photometric observations from the literature and constructed decades-long O-C diagrams of the stars. This traditional method is useful because of the single-periodic nature of the light variations. Text-book examples of slow period evolution (XX Cyg, DY Her, DY Peg) and cyclic period changes due to light-time effect (LITE) in a binary system (SZ Lyn) are updated with the new observations. For YZ Boo, we find a period decrease instead of increase. The previously suggested LITE-solution of BE Lyn (Kiss & Szatmary 1995) is not supported with the new O-C diagram. Instead of that, we suspect the presence of transient light curve shape variations mimicking small period changes.Comment: 11 pages, 15 figures, accepted for publication in A&

    Taxonomy and hierarchy of psychological abuse strategies in intimate partner relationships

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    This study focuses on the analysis from of a psychosocial perspective of the components of psychological abuse in intimate partner relationships. Following a review of studies on the subject, the main objective that emerged was the need for a new taxonomy of strategies of psychological abuse accompanied by the corresponding operational definitions. After the proposal of this new classification, a second objective emerged that consisted of submitting it for evaluation by a group of experts through a Delphi study, in which thirty-two experts from the academic and professional worlds participated. These experts were asked to assess the suitability of the system categories, and to grade quantitatively the severity of the impact made by each of the strategies on the global phenomenon of psychological abuse in couples. The results show that the experts ratified the new classification of strategies and their operational definitions, thus endorsing their content and construct validity. In addition, they classified the strategies based on their degree of severity; those of an emotional nature were considered the severest, followed by those related to the immediate context, with those of a cognitive type in third place, and lastly, the behavioural ones. Finally, we discuss the results, and their implications. Este estudio se centra en analizar los componentes del abuso psicológico en la violencia de pareja adulta y contra la mujer desde un enfoque psicosocial. Tras realizar una revisión de los estudios sobre el tema, se plantea como primer objetivo el proponer una nueva taxonomía de estrategias de abuso psicológico, acompañadas de sus respectivas definiciones operativas. A partir de esta nueva clasificación, se traza un segundo objetivo que se centra en someter esta clasificación al juicio de un grupo de expertos a través de un estudio Delphi, en el que han participado 32 expertos de los ámbitos académico - universitario y profesional. Estos expertos debían juzgar la adecuación del sistema de categorías, además de evaluar cuantitativamente la severidad que aporta cada una de las estrategias al fenómeno global del abuso psicológico en la pareja. Los resultados muestran que los expertos ratifican la nueva clasificación de estrategias y sus definiciones operativas, avalando así su validez de contenido y constructo. Además, jerarquizaron las estrategias de abuso, atribuyendo mayor severidad a las de tipo emocional, seguidas de las relacionadas con el contexto cercano, de las de tipo cognitivo y las de carácter conductual. Se discuten los resultados, sus limitaciones y las implicaciones que pueden derivarse de ellos

    Cation-driven electrical conductivity in Ta-doped orthorhombic zirconia ceramics

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    This paper is devoted to the study of the electrical conductivity of tantalum-doped zirconia ceramics prepared by spark plasma sintering. In this study, the temperature dependence of conductivity in as-prepared specimens and in those previously annealed in air is determined and compared. A semi-empirical model, which is based on the oxidation states of the cations, has been developed and successfully assessed. According to this, the conductivity is basically controlled by the diffusion of tetravalent zirconium cations in both cases, although the concentration of these species varies drastically with the amount of induced oxygen vacancies. This is a quite unexpected fact, since conductivity is normally controlled by anionic diffusion in zirconia ceramics. This option is forbidden here due to the presence of substitutional pentavalent cations. Therefore, conductivity values are much lower than those reported in trivalent or divalent substitutional cation doped zirconia ceramics
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