``Shadows in the X-ray Sky'', Space Physics and Astronomy Colloquium, Rice University, 25 April, 2000. ``Early Results from Chandra Observations of Supernova Remnants", Space Physics and Astronomy Colloquium, Rice University, 24 April, 2000.``Early Results from Chandra Observations of Supernova Remnants", Astrophysics and Planetary Sciences Colloquium, University of Colorado, 17 April, 2000.
``Early Results from Chandra Observations of Supernova Remnants", Joint Astrophysics/Nuclear Physics Seminar, Oxford University, Oxford, England, 13 April, 2000.
``Early Results from Chandra Observations of Supernova Remnants", Physics Colloquium, University of Leicester, Leicester, England, 10 April, 2000.
``Early Results from Chandra Observations of Supernova Remnants", Astronomy Colloquium, Osservatorio Astronomico di Brera, Milan University, Milan, Italy, 7 April, 2000.
``How to Catch 1000 Gamma-Ray Bursts'', Space Physics and Astronomy Colloquium, Rice University, 24 February, 2000.
``CUBIC and the Spectrum of the X-ray Background", Space Physics Colloquium, Los Alamos National Lab, 12 February 1997.
``ROSAT Observations of the Orion-Eridanus Superbubble'', Röntgenstrahlung from the Universe, International Conference on X-ray Astronomy and Astrophysics, Würzburg, Germany, 27 September, 1995.
``The CUBIC Instrument on SAC-B'', X-ray Astronomy Colloquium, Leicester University, Leicester, England, 30 June 1995.
``IRIS: A US/Argentine Soft X-ray Telescope for 2001'', Observatorio Astronomico de Cordoba, National University of Cordoba, Argentina, 27 March, 1995.
``X-ray Observations of the Supernova Remnant VRO42.05.01'', SNR Workshop, Instituto de Astronomia y Fisica del Espacio, University of Buenos Aires, Argentina, 29 March, 1995.
``Project IRIS'', IAR Colloquium, Instituto Argentino de Radioastronomia, Villa Elisa, Argentina, 4 May, 1994.
``IRIS: A US/Argentine Soft X-ray Telescope for 2001'', Observatorio Astronomico de la Plata, National University of La Plata, Argentina, 4 May, 1994. ``Low Latitude X-ray Shadows and the Soft X-ray Diffuse Background'', ROSAT Science Symposium, University of Maryland, 8 November, 1993.
``Shadows in the Sky: an X-ray Astronomer's Point of View'', Bucknell University Physics Colloquium, 15 October 1993.
``Recent Advances in X-ray CCDs'', Astrophysics Colloquium, University of Wisconsin, 23 August 1993.
``ROSAT Observations of X-ray Shadows'', APS meeting, Washington, D.C., 14 April 1993.
``Probing the Galactic Halo with ROSAT'', COSPAR Symposium on Recent Results in EUV and X-ray Astronomy at the World Space Congress, Washington, D.C., 1 September 1992.
``Soft X-ray Background Shadows: The Draco Cloud'', Astronomy Colloquium, University of Wisconsin, 27 August 1991.
``Soft X-ray Background Shadows: The Draco Cloud'', Space Physics Colloquium, Los Alamos Lab, 31 July 1991.
``The CUBIC Experiment'', Space Physics Colloquium, Los Alamos Lab, 30 July 1991.