"A Concert in Swing"; The Concert Band, The Pep Band, November 29, 1939

Concert program for "A Concert in Swing"; The Concert Band, The Pep Band, November 29, 1939

The Amplifier - v. 10, no. 2

In this issue...Beryllium, computer center, NASA, Democrats Club, football, Intramural Sports, Women's News, Fall tea, Bob Toivonen, Mineral Club, Miner's Bank

The Amplifier - v. 10, no. 1

In this issue...Homecoming Bonfire, campus interviews, Carol Melvin, Berkeley Pit, Pep Band, Chess Club, Alumni Coliseum, cheerleaders, Theta Tau, Mayor Thomas Powers

Fabrication and characterization of metal-semiconductor-metal (MSM) ultraviolet photodetectors on undoped GaN/sapphire grown by MBE

Interdigital metal-semiconductor-metal (MSM) ultraviolet photoconductive detectors have been fabricated on undoped GaN films grown by molecular beam epitaxy (MBE), Response dependence on wavelength, applied current, excitation powers and chopper frequency has been extensively investigated. It is shown that the photodetector's spectral response remained nearly constant for wavelengths above the band gap and dropped sharply by almost three orders of magnitude for wavelengths longer than the band gap. It increases linearly with the applied constant current, but very nonlinearly with illuminating power. The photodetectors showed high photoconductor gains resulting from trapping of minority carriers (holes) at acceptor impurities or defects. The results demonstrated the high quality of the GaN crystal used to fabricate these devices. (C) 2000 Elsevier Science B.V. All rights reserved.

Multi-band carrier-less amplitude and phase modulation for bandlimited visible light communications systems

Visible light communications is a technology with enormous potential for a wide range of applications within next generation transmission and broadcasting technologies. VLC offers simultaneous illumination and data communications by intensity modulating the optical power emitted by LEDs operating in the visible range of the electromagnetic spectrum (~370-780 nm). The major challenge in VLC systems to date has been in improving transmission speeds, considering the low bandwidths available with commercial LED devices. Thus, to improve the spectral usage, the research community has increasingly turned to advanced modulation formats such as orthogonal frequency-division multiplexing. In this article we introduce a new modulation scheme into the VLC domain; multiband carrier-less amplitude and phase modulation (m-CAP) and describe in detail its performance within the context of bandlimited systems.

DesignWorld : a tool for team collaboration in high band virtual environments

Current software tools for documenting and developing models of buildings focus on supporting a single user who is a specialist in the specific software used within their own discipline. Extensions to these tools for use by teams maintain the single discipline view and focus on version and file management. There is a perceived need in industry to have tools that specifically support collaboration among individuals from multiple disciplines with both a graphical representation of the design and a persistent data model. This project involves the development of a prototype of such a software tool. We have identified multi-user 3D virtual worlds as an appropriate software base for the development of a collaborative design tool. These worlds are inherently multi-user and therefore directly support collaboration through a sense of awareness of others in the virtual world, their location within the world, and provide various channels for direct and indirect communication. Such software platforms also provide a 3D building and modelling environment that can be adapted to the needs of the building and construction industry. DesignWorld is a prototype system for collaborative design developed by augmenting the Second Life (SL) commercial software platform1 with a collection web-based tools for communication and design. Agents manage communication between the 3D virtual world and the web-based tools. In addition, agents maintain a persistent external model of designs in the 3D world which can be augmented with data such as relationships, disciplines and versions not usually associated with 3D virtual worlds but required in design scenarios.

Application of Dynamic Hysteresis Band Height Control to Improve Output Voltage Transient in Boost and Positive Buck-Boost Converters

This paper presents dynamic hysteresis band height control to reduce the overshoot and undershoot issue on output voltage caused by load change. The converters in this study are Boost and Positive Buck-Boost (PBB) converters. PBB has been controlled to work in a step up conversion and avoid overshoot when load is changed. Simulation and experimental results have been presented to verify the proposed method.

The Cannabis Expectancy Questionnaire for Men who have Sex with Men (CEQ-MSM): A measure of substance-related beliefs

Objective Substance-related expectancies are associated with substance use and post-substance use thoughts, feelings and behaviours. The expectancies held by specific cultural or sub-cultural groups have rarely been investigated. This research maps expectancies specific to gay and other men who have sex with men (MSM) and their relationship with substance patterns and behaviours following use, including sexual practices (e.g., unprotected anal intercourse). This study describes the development of a measure of such beliefs for cannabis, the Cannabis Expectancy Questionnaire for Men who have Sex with Men (CEQ-MSM). Method Items selected through a focus group and interviews were piloted on 180 self-identified gay or other MSM via an online questionnaire. Results Factor analysis revealed six distinct substance reinforcement domains (“Enhanced sexual experience”, “Sexual negotiation”, “Cognitive impairment”, “Social and emotional facilitation”, “Enhanced sexual desire”, and “Sexual inhibition”). The scale was associated with consumption patterns of cannabis, and in a crucial test of discriminant validity not with the consumption of alcohol or stimulants. Conclusions The CEQ-MSM represents a reliable and valid measure of outcome expectancies, related to cannabis among MSM. Future applications of the CEQ-MSM in health promotion, clinical settings and research may contribute to reducing harm associated with substance use among MSM, including HIV transmission.

The Drinking Expectancy Questionnaire for Men who have Sex with Men (DEQ-MSM): A measure of substance-related beliefs

Introduction and Aims. Alcohol expectancies are associated with drinking behaviour and post-drinking use thoughts, feelings and behaviours. The expectancies held by specific cultural or sub-cultural groups have rarely been investigated. This research maps expectancies specific to gay and other men who have sex with men (MSM) and their relationship with substance use. This study describes the specific development of a measure of such beliefs for alcohol, the Drinking Expectancy Questionnaire for Men who have Sex with Men (DEQ-MSM). Design and Methods. Items selected through a focus group and interviews were piloted on 220 self-identified gay or other MSM via an online questionnaire. Results. Factor analysis revealed three distinct substance reinforcement domains ('Cognitive impairment', 'Sexual activity' and 'Social and emotional facilitation'). These factors were associated with consumption patterns of alcohol, and in a crucial test of discriminant validity were not associated with the consumption of cannabis or stimulants. Similarities and differences with existing measures will also be discussed. Discussion and Conclusions. The DEQ-MSM represents a reliable and valid measure of outcome expectancies, related to alcohol use among MSM, and represents an important advance as no known existing alcohol expectancy measure, to date, has been developed and/or normed for use among this group. Future applications of the DEQ-MSM in health promotion, clinical settings and research may contribute to reducing harm associated with alcohol use among MSM, including the development of alcohol use among young gay men.