Browsing by Author "Lira, P"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Natural killer cell leukemia. Case report
    (SOC MEDICA SANTIAGO, 2005) Guerrero, M; Lira, P; Bertin, P; Galleguillos, M; Ocqueteau, M
    Natural killer leukemia is a rare and highly aggressive neoplasm, is more common in young male patients and has a very poor prognosis, with a median survival of few weeks. We report a 17 years old male patient who developed, after an acute upper respiratory disease, a rapidly multiorganic failure with pancytopenia. Bone marrow aspiration and trephine biopsy showed an acute lymphoblastic leukemia. The immunophenotypic and immunohistochemistry revealed a natural killer acute leukemia. The disease progressed rapidly and the patient died shortly after the diagnosis.
  • No Thumbnail Available
    Item
    The multiwavelength survey by Yale-Chile (MUSYC)
    (2006) Gawiser, E; van Dokkum, PG; Herrera, D; Maza, J; Castander, FJ; Infante, L; Lira, P; Quadri, R; Toner, R; Treister, E; Urry, CM; Altmann, M; Assef, R; Christlein, D; Coppi, PS; Durán, MF; Franx, M; Galaz, G; Huerta, L; Liu, C; López, S; Méndez, R; Moore, DC; Rubio, M; Ruiz, MT; Toft, S; Yi, SK
    We present UBVRIz' optical images taken with MOSAIC on the CTIO 4 m telescope of the 0.32 deg(2) Extended Hubble Deep Field-South. This is one of four fields comprising the MUSYC survey, which is optimized for the study of galaxies at z=3, active galactic nucleus (AGN) demographics, and Galactic structure. Our methods used for astrometric calibration, weighted image combination, and photometric calibration in AB magnitudes are described. We calculate corrected aperture photometry and its uncertainties and find through tests that these provide a significant improvement upon standard techniques. Our photometric catalog of 62,968 objects is complete to a total magnitude of R-AB=25, with R-band counts consistent with results from the literature. We select z similar or equal to 3 Lyman break galaxy (LBG) candidates from their UVR colors and find a sky surface density of 1.4 arcmin(-2) and an angular correlation function w(theta) (2.3 +/- 1.0)theta(-0.8), consistent with previous findings that high-redshift Lyman break galaxies reside in massive dark matter halos. Our images and catalogs are available online.
  • No Thumbnail Available
    Item
    The physical nature of Lyα-emitting galaxies at z=3.1
    (2006) Gawiser, E; van Dokkum, PG; Gronwall, C; Ciardullo, R; Blanc, GA; Castander, FJ; Feldmeier, J; Francke, H; Franx, M; Haberzettl, L; Herrera, D; Hickey, T; Infante, L; Lira, P; Maza, J; Quadri, R; Richardson, A; Schawinski, K; Schirmer, M; Taylor, EN; Treister, E; Urry, CM; Virani, SN
    We selected 40 candidate Ly alpha-emitting galaxies ( LAEs) at z similar or equal to 3.1 with observed-frame equivalent widths greater than 150 and inferred emission-line fluxes above 2.5 x 10(-17) ergs cm(-2) s(-1) from deep narrowband and broadband MUSYC images of the Extended Chandra Deep Field South. Covering 992 arcmin(2), this is the largest "blank field" surveyed for LAEs at z similar to 3, allowing an improved estimate of the space density of this population of ( 3 +/- 1) x 10(-4) h(70)(3) Mpc(-3). Spectroscopic follow-up of 23 candidates yielded 18 redshifts, all at z similar or equal to 3.1. Over 80% of the LAEs are dimmer in continuum magnitude than the typical Lyman break galaxy ( LBG) spectroscopic limit of R = 25.5 ( AB), with a median continuum magnitude R similar or equal to 27 and very blue continuum colors, V-z similar or equal to 0. Over 80% of the LAEs have the right UVR colors to be selected as LBGs, but only 10% also have R <= 25.5. Stacking the UBVRIzJK fluxes reveals that LAEs have stellar masses similar or equal to 5 x 10(8) h(70)(-2) M-circle dot and minimal dust extinction, A(V) less than or similar to 0.1. Inferred star formation rates are similar or equal to 6 h(70)(-2) M-circle dot yr(-1), yielding a cosmic star formation rate density of 2 x 10(-3) h(70) M-circle dot yr(-1) Mpc(-3). None of our LAE candidates show evidence for rest-frame emission-line equivalent widths EWrest > 240 (A) over circle that might imply a nonstandard initial mass function. One candidate is detected by Chandra, implying an AGN fraction of 2% +/- 2% for LAE candidate samples. In summary, LAEs at z similar to 3 have rapid star formation, low stellar mass, little dust obscuration, and no evidence for a substantial AGN component.