396 research outputs found

    The Distribution of X-ray Dips with Orbital Phase in Cygnus X-1

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    We present results of a comprehensive study of the distribution of absorption dips with orbital phase in Cygnus X-1. Firstly, the distribution was obtained using archival data from all major X-ray observatories and corrected for the selection effect that phase zero (superior conjunction of the black hole) has been preferentially observed. Dip occurrence was seen to vary strongly with orbital phase \phi, with a peak at \phi ~ 0.95, i.e. was not symmetric about phase zero. Secondly, the RXTE ASM has provided continuous coverage of the Low State of Cygnus X-1 since Sept. 1996, and we have selected dip data based on increases in hardness ratio. The distribution, with much increased numbers of dip events, confirms that the peak is at \phi ~ 0.95, and we report the discovery of a second peak at \phi ~ 0.6. We attribute this peak to absorption in an accretion stream from the companion star HDE 226868. We have estimated the ionization parameter at different positions showing that radiative acceleration of the wind is suppressed by photoionization in particular regions in the binary system. To obtain the variation of column density with phase, we make estimates of neutral wind density for the extreme cases that acceleration of the wind is totally suppressed, or not suppressed at all. An accurate description will lie between these extremes. In each case, a strong variation of column density with orbital phase resulted, similar to the variation of dip occurrence. This provides evidence that formation of the blobs in the wind which lead to absorption dips depends on the density of the neutral component in the wind, suggesting possible mechanisms for blob growth.Comment: 9 pages, Latex, 7 ps figures. accepted by MNRA

    "Origo Constantini Imperatoris": comentario, notas y traducción

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    El objetivo de este artículo no es otro que presentar por primera vez una traducción al castellano de la "Origo Constantini Imperatoris", texto del s. IV dedicado a la vida y trayectoria política del emperador Constantino el Grande. Dicha traducción se presenta acompañada de un breve comentario histórico y literario con el que se pretende dar una visión global del estado actual de las investigaciones que esta obra ha generado.The aim of this paper is, basically, to present for the first time a Spanish translation of the "Origo Constantini Imperatoris". This is a text belonging to the 4th century, dedicated to Constantine the Great’s life and political course. The above mentioned translation is presented enclosed to a brief historic and literary commentary. It aims to give a general view of the current state of investigations that this work has generated.España. Ministerio de Educación y Ciencia AP20045943Aragón (Comunidad Autónoma) B037/200

    Ventilatory Threshold Responses at Different Percentages of Body Weight on the Alter-G Anti-Gravity Treadmill: A Pilot Study

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    Santillo, N., Figueroa, M., Lasala, T., Manning, J., William Paterson University, Wayne NJ Purpose: The purpose of this study was to determine if changes occurred in the ventilatory threshold (VT) upon manipulation of body weight (BW) when comparing 80% to 100% of BW in healthy college aged individuals on the Alter-G® anti-gravity treadmill. Methods: A modified Bruce Protocol was used to measure oxygen consumption (VO2peak) on 10 subjects (5 males, 5 females) at 100%, and 80% of BW. Testing protocols were randomized with two weeks in between each test. VT was determined by the software algorithm in the MedGraphics Ultima Series (St. Paul, MN) open exchange spirometer. Results: Gender did not significantly affect relative VO2peak or VT at either percentage of BW. No significant differences were found with regards to VO2peak (ml×kg-1×min-1) or VT at 100%BW & 80% BW. Conclusion: Upon the unweighting of a subject on the Alter-G® anti-gravity treadmill, individuals are able to train at similar intensities at 80% and 100% of BW. Since the unweighting produced similar metabolic responses, one could suggest that those with orthopedic limitations, who are not fully weight bearing, can maintain their cardiovascular conditioning. This type of training may also be advantageous for athletes who wish to reduce musculoskeletal strain within their training

    THE EFFECT OF A 7-WEEK PROGRESSIVE YOGA INTERVENTION ON HAMSTRINGS FLEXIBILITY

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    Revision and conservation status of the bryological flora from Sierra de Peña Sagra (Cordillera Cantábrica, Spain)

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    Se analiza el porcentaje de especies de briófitos amenazados del catálogo de la Sierra de Peña Sagra (Cantabria). Se aportan 4 nuevos taxones a la Lista Roja de Briófitos de la Península Ibérica: Anastrepta orcadensis, Plagiochila spinulosa, Orthotrichum consimile y Sphagnum brevifolium. Se plantea el cambio de categoría de amenaza de Bazzania tricrenata. Se propone la inclusión de esta zona en la lista de Humedales de Importancia Internacional como sitio Ramsar.The percentage of threatened taxa in the list of bryophytes of Sierra de Peña Sagra (Cantabria) is analysed. 4 new taxa are added to the Red List of Bryophytes of the Iberian Peninsula: Anastrepta orcadensis, Plagiochila spinulosa, Orthotrichum consimile and Sphagnum brevifolium. A change in the threat category of Bazzania tricrenata is suggested. We propose the inclusion of this locality in the Ramsar List of Wetlands of International Importance

    Aportación al conocimiento de la flora briológica española. Nótula IV: las Sierras de Jabalambre y Gúdar (Teruel)

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    La VII Reunión de Briología tuvo lugar los días 5 al 9 de abril de 1976 en Mora de Rubielos, con objeto de continuar el estudio del Sistema Ibérico iniciado con la Sierra de Albarracín. Durante las jornadas de trabajo se exploraron las sierras de Jabalambre y Gúdar. En esta comunicación damos a conocer el resultado de nuestras recolecciones en ambas Sierras. Después de un somero estudio de la vegetación de la zona objeto de nuestro trabajo, se da a conocer la presencia de 17 especies de Hepáticas y 125 de Musgos. Este resultado representa la primera aportación para esta parte del Sistema Ibérico y una notable contribución al conocimiento de la brioflora turolense.The VII Bryological Meeting took place on the 5th to the 9th of April, 1976 in Mora de Rubielos, its aim being to continue the study of the Iberian System which began in the Sierra de Albarracín. Work done during the Meeting consisted in exploring the sierras ofJabaIambre and Gúdar. The result of our gatherings in both these sierras is made known in this article. After a summary study ofthe vegetation of the area which was the subject of our investigation, the presence of 17 species of Hepaticae and 125 of Mosses is discovered. These results form the first contribution for this part of the Iberian System and an important contribution to the knowledge of the Teruel bryoflora

    Petrological and chronological considerations on the hercynian granitic rocks from Galicia (NW Spain)

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    [Resumen] Se realiza un estudio sobre más de 600 análisis químicos correspondientes a los diversos grupos de granitoides hercínicos de Galicia, y se establecen valores medios representativos para la composición química mayoritaria de estos grupos. La comparación con las medias previamente establecidas para el N. O. de Galicia, permite observar un desplazamiento hacia términos composicionales más ácidospara el conjunto de los granitoides sincinemáticos más profundos, que resulta notablemente más acentuado en el grupo de los granitoides sincinemáticos predominantemente biotíticos. Para los granitoides postcinemáticos, las desviaciones observadas son en cambio poco significativas. El examen de los datos normativos medios, pone en evidencia un carácter peralumínico generalizado para todo el conjunto, apreciándose no obstante un drástico descenso en el contenido en corindón para los granitoides postcinemáticos, que marca una distribución bimodal para este componente normativo. La clasificación petrológica con base en la mineralogía normativa pone de manifiesto un espectro composicional que fluctúa esencialmente entre granitos y monzogranitos, con muy escasa representación de los términos granodior1ticos. La variabilidad observada para los elementos mayores más signiflcativos presenta pautas poco dispersivas. Los espectros de tierras raras tienen una configuración muy similar para los granitoides precoces predominantemente biotíticos, los granitos de dos micas sincinemáticos y los granitoides inhomogéneos, con anomalías negativas de Eu poco acentuadas. Por el contrario, los granitoides tardicinemáticos someros y los granitoides post-cinemáticos, presentan también espectros bastante similares entre sí, con anomalís negativas de Eu que pueden ser considerables. Las dataciones cronológicas efectuadas por el método de Rb-Sr en roca total en algunos de los plutones post-cinemáticos se encuentran en un intervalo aproximado de 275-287 m. a., mientras que la mayoría de las dataciones sobre unidades sincinemáticas de dos micas y predominantemente biotíticas fluctúan entre 295 y 323 m. a., aunque se encuentran algunos datos fuera de este entorno, que precisan futuras verificaciones..[Abstract] A survey over more than 600 chemical analysis of Hercynian granitic rocks from Galicia is presented, and a new set of representative mean compositional values of the main groups is calculated. In general, these new mean values are richer in Si02 than the previously available ones. This difference is more conspicous in the biotite rich synkinematic group, and is minium in the postkynematic granitoids. The average normative compostion, shows a systematic peraluminous character for aH the granitoids. However, the group of postkynematic granitoids, are poorer in normative corundum than the other groups, which results in a bimodal distribution of this normative component. The normative petrological c1assification shows a compositional spectrúm ranging mainly from granites to monzogranites. The Granodioritic rocks are very scarce. The variation trends for the main mayor elements display patterns with little dispersion. The REE spectra for the biotite rich synkinematic granites, two mica synkinematic granites and inhomogenous granites are very similar, and show negligible Eu anomalies. By contrast, the shaHow level intrusion late-kynematic and postkynematic granites, display conspicous Eu anomalies and have similar spectra patterns, but different from the previously referred ones. Whole-rock-Rb-Sr ages for the postkynematic plutons range from 287 to 275 M. y. The majority of the data the synkinematic units range from 323 to 295 M. y. However, sorne chronological data faH out of these intervals, showing the need of further studies
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