The time-of-flight system on the Goddard medium energy gamma-ray telescope

A scintillation counter time of flight system, incorporated into the Goddard 50 cm by 50 cm spark chamber gamma ray telescope is described. The system, which utilizes constant fractions timing and particle position compensation and digitizes up to 10 ns time differences to six bit accuracy in less than 500 ns is analyzed. The performance of this system during balloon flight is discussed

How User Personality and Social Value Orientation Influence Avatar Mediated Friendship

Purpose – The purpose of this paper is to study the influence of user personality and vlaues on the number of connections users make, the number of requests for connections that users give out, and the number of connections invitations users receive. Design/methodology/approach – This is a field study of 179 participants interacting in a novel virtual world. The world’s server logs are used to capture sociometrics about the users and their interaction. Findings – Findings suggest that personality and values influence the number of friends users make and the number of friendship requests users give out, but not the number of friendship invitations users receive. Only one personality trait – conscientiousness – exhibits homophily. Originality/value – Personality and social value orientation have rarely been studied together in information systems (IS) research, despite research showing the two have an impact on IS relevant constructs. The use of server logs for data capture is novel. Avatar friendship is an under-researched concept in IS

High performance VLSI telemetry data systems

NASA's deployment of major space complexes such as Space Station Freedom (SSF) and the Earth Observing System (EOS) will demand increased functionality and performance from ground based telemetry acquisition systems well above current system capabilities. Adaptation of space telemetry data transport and processing standards such as those specified by the Consultative Committee for Space Data Systems (CCSDS) standards and those required for commercial ground distribution of telemetry data, will drive these functional and performance requirements. In addition, budget limitations will force the requirement for higher modularity, flexibility, and interchangeability at lower cost in new ground telemetry data system elements. At NASA's Goddard Space Flight Center (GSFC), the design and development of generic ground telemetry data system elements, over the last five years, has resulted in significant solutions to these problems. This solution, referred to as the functional components approach includes both hardware and software components ready for end user application. The hardware functional components consist of modern data flow architectures utilizing Application Specific Integrated Circuits (ASIC's) developed specifically to support NASA's telemetry data systems needs and designed to meet a range of data rate requirements up to 300 Mbps. Real-time operating system software components support both embedded local software intelligence, and overall system control, status, processing, and interface requirements. These components, hardware and software, form the superstructure upon which project specific elements are added to complete a telemetry ground data system installation. This paper describes the functional components approach, some specific component examples, and a project example of the evolution from VLSI component, to basic board level functional component, to integrated telemetry data system

Determinants of Friendship in Social Networking Virtual Worlds

This paper examines the determinants of friendship between two users in a virtual world who are unaware of each other's real identities. Drawing on theories of homophily, heterophily and propinquity, three virtual world behaviours are analysed: avatar appearance, avatar location, and avatar communication. Data are collected on 179 participants interacting in a novel virtual world. The main results show that: (1) avatars did not tend to form friendships with avatars that are similar in appearance to themselves but did tend to form friendships with avatars that are dressed differently from themselves; (2) in terms of location, the closer an avatar stands to other avatars, the more likely the avatar is to receive a friend invitation; and (3) the fewer words an avatar uses in communication, the more likely the avatar is to receive a friend invitation. This paper contributes to theories of virtual world interaction and to using virtual worlds as a data collection platform

Polyspecies aquaculture systems: The detrital trophic level

The production of species belonging to the detrital trophic level was investigated in a model-sized aquaculture system, with flowing, filtered seawater and controlled phytoplankton addition to experimental tanks containing the oyster, Crassostrea virginica. The biodeposits of feces and pseudofeces of the oysters supported on the bottom of one tank a population of the nereid polychaete, Nereis virens and in the other tank a mixed community of the capitellid polychaete, Capitella capitata and the amphipod, Corophium sp...