This paper reexamines the rules of thumb for the design of data storage systems. Briefly, it looks at storage, processing, and networking costs, ratios, and trends with a particular focus on performance and price/performance. Amdahl’s ratio laws for system design need only slight revision after 35 years—the major change being the increased use of RAM. An analysis also indicates storage should b...

From millimeter observations of classical T Tauri stars, it is suggested that dust grains in circumstellar disks have grown to millimeter size or larger. However, gas drag on such large grains induces rapid accretion of the dust. We examined the evolution of dust disks composed of millimeter sized grains, and showed that rapid accretion of the dust disk causes attenuation of millimeter continuu...

Context. Grain growth in protoplanetary disks is the first step towards the formation of the rocky cores of planets. Models predict that grains grow, migrate, and fragment in the disk and predict varying dust properties as a function of radius, age, and physical properties. High-angular resolution observations at more than one (sub-)mm wavelength are the essential tool for constraining grain gr...

Results of a 1999 November 16–17 BeppoSAX observation of the low-mass X-ray binary X 2127+119 located in the globular cluster M15 are presented. The system is believed to be one where the central neutron star is normally obscured by the accretion disk, and only X-rays scattered into our line of sight by an extended accretion disk corona (ADC) are observed. The 0.1–10 keV lightcurve is energy de...

Results of a 1999 November 16–17 BeppoSAX observation of the low-mass X-ray binary X 2127+119 located in the globular cluster M15 are presented. The system is believed to be one where the central neutron star is normally obscured by the accretion disk, and only X-rays scattered into our line of sight by an extended accretion disk corona (ADC) are observed. The 0.1–10 keV lightcurve is energy de...

The Sloan Digital Sky Survey (SDSS) source J102347.6+003841 was recently revealed to be a binary 1.69 millisecond radio pulsar with a 4.75 hr orbital period and a ∼0.2 M⊙ companion. Here we analyze the SDSS spectrum of the source in detail. The spectrum was taken on 2001 February 1, when the source was in a bright state and showed broad, double-peaked hydrogen and helium lines — dramatically di...

The damped Lyα absorbers (DLAs) in quasar spectra are believed to be the progenitors of present–day disk galaxies. We examine the probability for microlensing of background quasars by stars in their DLAs. Microlensing should magnify the continuum but not the broad emission lines of the quasars. We model a representative spiral galaxy as a closed system composed of a bulge, a disk, and a halo, a...

Using a simple model of molecular cloud evolution, we have quantitatively estimated the change of star formation rate (SFR) of a disk galaxy falling radially into the potential well of a cluster of galaxies. The SFR is affected by the ram-pressure from the intracluster medium (ICM). As the galaxy approaches the cluster center, the SFR increases to twice the initial value, at most, in a cluster ...

We report on the long term monitoring of X-ray dips from the ultracompact low-mass X-ray binary (LMXB) XB 1916-053. Roughly one-month interval observations were carried out with the Rossi X-ray Timing Explorer (RXTE) during 1996, during which the source varied between dim, hard states and more luminous, soft states. The dip spectra and dip lightcurves were compared against both the broadband lu...