Michael J. West

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This paper presents the design and rationale of a distributed file system for a network of more than 5000 personal computer workstations. While scale has been the dominant design influence, careful attention has also been paid to the goals of location transparency, user mobility and compatibility with existing operating system interfaces. Security is an(More)
Imaging surveys with the Hubble Space Telescope (HST) have shown that ≈ 50–80% of lowand intermediate-luminosity galaxies contain a compact stellar nucleus at their center, regardless of host galaxy morphological type. We combine HST imaging for early-type galaxies from the ACS Virgo Cluster Survey with ground-based long-slit spectra from KPNO to show that(More)
The possibility that the Galactic spheroid was assembled from numerous, chemically-distinct protoGalactic fragments is investigated using a Monte-Carlo technique designed to simulate the chemical evolution of the Galaxy in hierarchical formation scenarios which involve no gas dissipation. By comparing the observed and simulated metallicity distributions of(More)
We present a detailed analysis of the morphology, isophotal parameters and surface brightness profiles for 100 early-type members of the Virgo Cluster, from dwarfs (MB = −15.1 mag) to giants (MB = −21.8 mag). Each galaxy has been imaged in two filters, closely resembling the Sloan g and z passbands, using the Advanced Camera for Surveys on board the Hubble(More)
Nearly a century after the true nature of galaxies as distant 'island universes' was established, their origin and evolution remain great unsolved problems of modern astrophysics. One of the most promising ways to investigate galaxy formation is to study the ubiquitous globular star clusters that surround most galaxies. Globular clusters are compact groups(More)
The ACS Virgo Cluster Survey is a Hubble Space Telescope program to obtain high-resolution imaging, in widely separated bandpasses (F475W ≈ g and F850LP ≈ z), for 100 early-type members of the Virgo Cluster, spanning a range of ≈ 460 in blue luminosity. We use this large, homogenous dataset to examine the innermost structure of these galaxies and to(More)
An easy to perform autometallographic technique (AMG) for capturing zinc ions in Alzheimer plaques is presented. The possibility of visualizing loosely bound or free zinc ions in tissue by immersion autometallography (iZnSAMG) is a relatively recent development. The iZnSAMG staining is caused by zinc-sulphur nanocrystals created in 1–2 mm thick brain slices(More)
We present (g475−z850) color and z850-band surface brightness fluctuations (SBF) measurements for 43 earlytype galaxies in the Fornax cluster imaged with the Hubble Space Telescope Advanced Camera for Surveys. These are combined with our earlier measurements for Virgo cluster galaxies to derive a revised, nonlinear calibration of the z850-band SBF absolute(More)
We analyze the metallicity distributions of globular clusters belonging to 28 early-type galaxies in the survey of Kundu & Whitmore (2001). A Monte Carlo algorithm which simulates the chemical evolution of galaxies that grow hierarchically via dissipationless mergers is used to determine the most probable protogalactic mass function for each galaxy.(More)