Browsing by Author "Ramirez, A"

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    Dynamics of the cluster of galaxies A3266 (Sersic 40/6) .1. Spectroscopic data
    (1996) Quintana, H; Ramirez, A; Way, MJ
    We present 387 velocities covering an area 1.8 degrees x1.8 degrees, including 229 new galaxy velocities obtained from 309 spectra, of which 317 appear to be cluster members according to our analysis. Based on this extended velocity sample we reanalyzed the velocity structure of the cluster. We found a strongly decreasing velocity dispersion profile that, as well as the mean velocity, shows significant radial scatter. Inside the 2.5h(50)(-1) Mpc radius, the velocity dispersion has a value of 1306+/-73 km s(-1), while further out than 3h(50)(-1) Mpc it falls below 800 km s(-1). The global dispersion is 1085+/-51 km s(-1). We found a remarkable velocity substructure, which we interpret as a tidal outgoing arm reaching from the center to the northernmost extensions surveyed. The arm could be produced by a recent merger with another cluster, that moved from the front and SW direction and scattered from the main cluster core into the arm. This model allows us to derive an epoch for the collision between the more massive core and the front edge of the incoming cluster of 4X10(9)h(50)(-1) yr ago and of similar to 2X10(9)h(50)(-1) yr for the merging of both cores. Formation of the dumb-bell is a later merger process of the two BCMs, consistent with theoretical estimates. The collision picture is also consistent with the distorted x-ray image. The very northernmost parts of the arm could, alternatively, be interpreted as ongoing infall of a few outlying loose groups. The suggestion of a faint galaxy system within 400h(50)(-1) kpc, satellite to the central dumb-bell, is maintained in spite of the large central velocity dispersion value; however, confirmation requires data for further compact faint members. From several mass estimators we derived a cluster dynamical mass value of 5X10(15)h(50)(-1) M(.), but this value should be seen in the merger context described. (C) 1996 American Astronomical Society.
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    Spectroscopy of the NGC 4782/3 dumbbell dominated group of galaxies: Dark haloes and merger of subgroups
    (1996) Quintana, H; Ramirez, A; Way, MJ
    A nearly complete sample of new velocities for 96 galaxies covering an area 1 degrees X1.25 degrees centered on NGC 4782/3 are presented, Including data from the literature a total of 125 velocities are compiled. We deduce that 40 galaxies are likely members of the group centered on NGC 4782/3, more than doubling the original confirmed 13 members. Based on this extended velocity sample we analyze the velocity structure of this unusual group. A bi-modal velocity structure centered on each of the dumbbell components provides evidence for an ongoing collision of two subgroups associated to these components. In velocity space the richer subgroup is centered on the more massive NGC 4782. From the subgroup dynamics we derive approximate dynamical masses of 5X10(13) M. and 1X10(13) M. for the NGC 4782 and NGC 4783 subgroups, respectively, This leads to a group M/L approximate to 300 (M/L)., implying that similar to 90% of the group mass is in dark form, within subsystems associated to each subgroup, The colliding elliptical galaxies have massive haloes which should be important in shaping the outcome of the collision and merger process, In particular, haloes could change the interpretation of the tidal distortions and play a role in the shaping of the radio double bent jet structure of 3C 278. (C) 1996 American Astronomical Society.
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    The effect of transport on cortisol, glucose, heart rate, leukocytes and body weight in captive-reared guanacos (Lama guanicoe)
    (UNIV FEDERATION ANIMAL WELFARE, 2004) Zapata, B; Gimpel, J; Bonacic, C; Gonzalez, B; Riveros, J; Ramirez, A; Bas, F; Macdonald, DW
    Current procedures for ranching and sustainable use of guanacos necessitate their transport. Transportation is a risky process for animals, and is a particular concern for wild-caught or semi-domesticated species such as the guanaco - a wild South American comelid species increasingly being established on forms in Chile and Argentina. This study investigated the effect of transport on the physiological and behavioural responses of eight castrated adult male guanocos, transported on a single 2 h journey at a stocking density of 113.5 kg m(-2) (0.76 m(2) per animal). Plasma cortisol and blood glucose concentration, total and differential white blood cell (WBC) counts, heart rate, and body weight were measured one week before, immediately before, immediately after, 2 h after and one week after transport. Behavioural responses were recorded during handling prior to loading. Immediately after transport we found significant increases in plasma cortisol concentrations and neutrophil. lymphocyte (N:L) ratio, the latter peaking 2 h after transport. Heart rate increased significantly only during loading, while body weight remained constant throughout. Behavioural responses related to handling (Jumping, vocalising, kicking, spitting and urinating) were not associated with the physiological response. All variables returned to pre-transport values within one week. Transport of guanacos under these conditions produced physiological changes similar to those associated with a mild and transient stress response in other species and which, we judge, fall comfortably within acceptable limits for their welfare.