First Results from Photon Multiplicity Detector at RHIC

We present the first measurement of multiplicity and pseudorapidity distributions of photons in the pseudorapidity region 2.3 < eta < 3.7 for different centralities in Au + Au collisions at sqrt{s_NN} = 62.4 GeV. The pseudorapidity distribution of photons, dominated by neutral pion decays, has been compared to those of identified charged pions, photons, and inclusive charged particles from heavy ion and nucleon-nucleon collisions at various energies. Scaling of photon yield with number of participating nucleons and limiting fragmentation scenario for inclusive photon production has been studied.Comment: Talk given at 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma (February 8 - 12, 2005); 4 pages and 6 figure

THE LOCATION DECISION OF HARDWOOD MANUFACTURING IN THE NORTHERN AND CENTRAL APPALACHIAN STATES

This study's objective is to identify and understand the factors important to hardwood processors' location decisions in the northern and central Appalachian region. Concepts from neoclassical and behavioral location theories were integrated to develop a general framework for analyzing these decisions. Logit regression analysis was used to determine those establishment characteristics related to the likelihood of location search. To a great extent, establishments locate based on personal ties and do not conduct searches. Most variables found to influence the likelihood of search are not controllable by state or local governments. The implications are that existing establishments should be targeted for retention and expansion, rather than focusing on recruitment.Community/Rural/Urban Development, Industrial Organization,

A twin-mirrored galvanometer laser light sheet generator

A galvanometer mirror-based laser light sheet system has been developed for use in the Basic Aerodynamics Research Tunnel at NASA Langley. This system generates and positions single or multiple light sheets over aeronautical research models being tested in the low speed tunnel. This report describes a twin mirrored galvanometer laser light sheet generator and shows typical light sheet arrangements in use. With this system, illumination of smoke entrained in the flow over a delta wing model reveals the vortical flow produced by the separation of the flow at the leading edge of the model. The light sheet system has proven to be very adaptable and easy to use in sizing and positioning light sheets in wind tunnel applications

Predictable scheduling for digital audio

ManuscriptThis paper presents results from applying the Rialto/ NT scheduler to some real Windows 2000 application scenarios. We report on two aspects of this work. First, we studied the reliability of an audio player application and the middleware and kernel components running beneath it in order to assess its reliability under various concurrent application loads. Then we added CPU Reservations to portions of the workload in order to determine if doing so would increase playback reliability under workloads in which problems were previously seen. We report on the benefits and problems observed when using reservations in these real-world scenarios. We also describe the methodologies we used to analyze the real-time behavior of the operating system and applications, including the use of instrumented kernels to produce execution traces. Finally, we describe several improvements in the Rialto/NT implementation that have been made since the system was originally described

The problems you're having may not be the problems you think you're having: results from a latency study of windows NT

ManuscriptThis paper is intended to catalyze discussions on two intertwined systems topics. First, it presents early results from a latency study of Windows NT that identifies some specific causes of long thread scheduling latencies, many of which delay the dispatching of runnable threads for tens of milliseconds. Reasons for these delays, including technical, methodological, and economic are presented and possible solutions are discussed. Secondly, and equally importantly, it is intended to serve as a cautionary tale against believing one's own intuition about the causes of poor system performance. We went into this study believing we understood a number of the causes of these delays, with our beliefs informed more by conventional wisdom and hunches than data. In nearly all cases the reasons we discovered via instrumentation and measurement surprised us. In fact, some directly contradicted "facts" we thought we "knew"

Issues in using commodity operating systems for time-dependent tasks: experiences from a study of windows NT

ManuscriptThis paper presents a snapshot of early results from a study of Windows NT aimed at understanding and improving its limitations when used for time-dependent tasks, such as those that arise for audio and video processing. Clearly there are time scales for which it can achieve effectively perfect reliability, such as the onesecond deadlines present in the Tiger Video Filesystem. Other time scales, such as reliable sub-millisecond scheduling of periodic tasks in user space, are clearly out of reach. Yet, there is an interesting middle ground between these time scales in which deadlines may be met, but will not always be. This study focuses on system and application behaviors in this region with the short-term goals of understanding and improving the real-time responsiveness of applications using Windows NT 5.0 and a longer-term goal of prototyping and recommending possible scheduling and resource management enhancements to future Microsoft systems products. Finally, while this paper primarily contains examples and results from Windows NT, we believe that the kinds of limitations and artifacts identified may also apply to other commodity systems such as the many UNIX variants. Indeed, this paper is primarily intended to provide a starting point for fruitful discussions along these lines at the workshop and not as a record of completed work

CPU reservations and time constraints: implementation experience on windows NT

Journal ArticleThis paper presents an implementation of scheduling abstractions originally developed for the Rialto real-time operating system within a research version of Windows NT called Rialto/NT. These abstractions, CPU Reservations and Time Constraints, as described in the 1997 SOSP paper [Jones et al. 97], are intended to allow: (1) activities to obtain minimum guaranteed execution rates with application-specified reservation granularities via CPU Reservations, and (2) applications to schedule tasks by deadlines via Time Constraints, with on-time completion guaranteed for tasks with accepted constraints. The Rialto/NT scheduler differs from the original Rialto scheduler in several key respects. First, it has been extended to schedule multiprocessors-this is the primary new intellectual contribution of this work. It has been adapted to operate with operating system clock services that only provide timing interrupts at regular periodic intervals measured in milliseconds, rather than being able to schedule clock interrupts at arbitrary sub-millisecond points of time. It coexists with the existing Windows NT scheduler, allowing it to schedule time not scheduled by itself. Finally, it has been implemented in a particularly non-intrusive manner, using rather than replacing the existing Windows NT priority-based scheduler. Results presented will demonstrate that CPU Reservations and Time Constraints can be effectively implemented on multiprocessors. We will also describe the implementation techniques chosen and tradeoffs made as a result of implementing within Windows NT. Finally, we will present performance results and execution traces