We present experimental results on fragmentation charge-changing cross sections of 158 A GeV lead ions (charge Z = 82e) incident on Cu and CR39 targets. To detect and identify the relativistic ions, the nuclear track detector CR39 was used. When an ion crosses a nuclear track detector foil, it produces damages at the level of molecular bonds, forming the so called “latent track”. During the che...

During remarkable aring activity in 1997 Markarian 501 was the brightest source in the sky at TeV energies, outshining the Crab Nebula by a factor of up to 10. Periods of aring activity each lasting a few days were observed simultaneously by several gamma ray telescopes. Contemporaneous multiwavelength observations in April 1997 show that a substantial fraction of the total AGN power is at TeV ...

A Picture Archiving and Communication System (PACS) will operate in a hospital and provide a totally digital environment for storing and retrieving medical images, diagnostic reports, and patient data [1]. Generally speaking, a PACS consists of a communication network and three types of network nodes: imaging equipment, viewing workstations and database archive system. Imaging equipment nodes a...

Providing WWW or FTP service on a small scale is already a well-solved problem. Scaling this to work at a site that accepts millions of connections per day, however, can easily push multiple machines and networks to the bleeding edge. In this paper, we give concrete configuration techniques that have helped us get the best possible performance out of server resources. Our analysis is mostly cen...

Programmers spend a significant part of their time debugging, yet most of them simply add print statements and avoid debugging tools. Although the user interface of debuggers has improved significantly in the past decade, their basic debugging methodologies have changed little. This thesis examines single-process sequential debuggers and attempts to elucidate their weaknesses. Target-state expl...

Mantle-derived garnet peridotites are a minor component in many very high-pressure metamorphic terranes that formed during continental subduction and collision. Some of these mantle rocks contain trace amounts of zircon and micrometer-sized inclusions. The constituent minerals exhibit pre- and postsubduction microstructures, including polymorphic transformation and mineral exsolution. Experimen...

Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modul...

Fabrication and readout of devices with progressively smaller size, ultimately down to the molecular scale, is critical for the development of very-high-frequency nanoelectromechanical systems ~NEMS!. Nanomaterials, such as carbon nanotubes or nanowires, offer immense prospects as active elements for these applications. We report the fabrication and measurement of a platinum nanowire resonator,...

Electron energy-loss spectroscopy (EELS) has been investigated in the range from 2 to >10 keV using an optimized optical coupling of the microscope to the spectrometer to improve the high loss performance in EELS. It is found that excellent quality data can now be acquired up until about 5 keV, suitable for both energy loss near edge structure (ELNES) studies of oxidation and local chemistry, a...