Cool thermal emission components have recently been revealed in the X-ray spectra of a small number of ultraluminous X-ray sources (ULXs) with ergs s 1 in nearby galaxies. These components can be well 40 L ≥ 10 X fitted with accretion disk models, with temperatures approximately 5–10 times lower than disk temperatures measured in stellar-mass Galactic black holes when observed in their brightes...

In the past decade, parallel disk systems have been highly scalable and able to alleviate the problem of disk I/O bottleneck, thereby being widely used to support data-intensive applications. Although a variety of parallel disk systems were developed, most existing disk systems lack a means to adaptively control the quality of security for dynamically changing workloads. We address this gap in ...

Thick disks are faint and extended stellar components found around several disk galaxies including our Milky Way. The Milky Way thick disk, the only one studied in detail, contains mostly old disk stars (≈ 10 Gyr), so that thick disks are likely to trace the early stages of disk evolution. Previous detections of thick disk stellar light in external galaxies have been originally made for early-t...

The disk in the center of M87 is a prototype for gas orbiting a massive central object. Three sets of HST+COSTAR FOS and FOC observations provide strong evidence that the nuclear disk in M87 is in Keplerian rotation around a black hole with a mass of (2 − 3) × 10 9 M⊙. A deep (6 orbits), high resolution Hα+[N ii] PC2 HST image shows a trailing, three arm spiral superposed on the underlying nucl...

The dramatic increase of HTTP traffic on the Internet has resulted in wide-spread use of large caching proxy servers as critical Internet infrastructure components. With continued growth the demand for larger caches and higher performance proxies grows as well. The common bottleneck of large caching proxy servers is disk I/O. In this paper we evaluate ways to reduce the amount of required disk ...

One of the persistently exciting control applications is that of disk drive servos. From the start in the early 1950s to the massive capacity commodity drives of the early 2000s, the problem of accessing data on rotating disk media has provided a wealth of control challenges to be solved. This survey paper traces the early history of disk drive control from the first disk drive in 1956 to the f...