New symmetry current for massive spin-3/2 fields

We present several new results which will be of value to theorists working with massive spin-3/2 vector-spinor fields as found, for example, in low and intermediate energy hadron physics and also linearized supergravity. The general lagrangian and propagator for a vector-spinor field in d-dimensions is given. It is shown that the observables of the theory are invariant under a novel continuous symmetry group which is also extended to an algebra. A new technique is developed for exploring the consequences of the symmetry and a previously unknown conserved vector current and charge are found. The current leads to new interactions involving spin-3/2 particles and may have important experimental consequences.Comment: 9 pages, references updated and minor change

Subtleties in the quasi-classical calculation of Hawking radiation

he quasi-classical method of deriving Hawking radiation is investigated. In order to recover the original Hawking temperature one must take into account a previously ignored contribution coming from the temporal part of the action. This contribution plus a contribution coming from the spatial part of the action gives the correct temperature.Comment: 6 pages revtex. Honorable Mention in 2008 GRF essay contest, typos fixed, sign errors corrected. To be published in Special Issue of IJMP

Disabled people and the Internet: experiences, barriers and opportunities

The UK government aims to make all its information and transactions available electronically by 2005. General use of the Internet also continues to grow. This report investigates the Internet's barriers and benefits for disabled people, and considers whether it acts as a means to reduce their social exclusion. The study surveys the views and experiences of disabled people, both Internet users and non-users. Topics covered include: what the Internet is used for; use of and difficulties with assistive devices (special equipment and adaptations needed by some disabled people in order to use computers); how people learn to use the Internet; views of website accessibility; advantages and disadvantages of Internet usage. It also explores participants' restrictions on using the Internet, and people's reasons for not using it. There has been little previous research in this area, but the authors review the existing literature. The report finds that many practical problems - such as the cost of training, finding appropriate assistive devices, website accessibility - all inhibit Internet opportunities for many disabled people

A computerized Langmuir probe system

For low pressure plasmas it is important to record entire single or double Langmuir probe characteristics accurately. For plasmas with a depleted high energy tail, the accuracy of the recorded ion current plays a critical role in determining the electron temperature. Even for high density Maxwellian distributions, it is necessary to accurately model the ion current to obtain the correct electron density. Since the electron and ion current saturation values are, at best, orders of magnitude apart, a single current sensing resistor cannot provide the required resolution to accurately record these values. We present an automated, personal computer based data acquisition system for the determination of fundamental plasma properties in low pressure plasmas. The system is designed for single and double Langmuir probes, whose characteristics can be recorded over a bias voltage range of ±70 V with 12 bit resolution. The current flowing through the probes can be recorded within the range of 5 nA–100 mA. The use of a transimpedance amplifier for current sensing eliminates the requirement for traditional current sensing resistors and hence the need to correct the raw data. The large current recording range is realized through the use of a real time gain switching system in the negative feedback loop of the transimpedance amplifier

US and UK Routes to Employment: Strategies to Improve Integrated Service Delivery to People with Disabilities

In this report, the authors examine the experience of the United States and United Kingdom in developing effective strategies for providing integrated service delivery. The report examines what works and what doesn't work, and provides a roadmap to improving services for individuals with disabilities. While more research is needed, the report identifies 12 strategies to strengthen integrated service delivery systems, and to assist individuals with disabilities in gaining and maintaining productive employment. Implementing these strategies can benefit clients, who have the opportunity to realize their potential more fully; the taxpayer, who is paying less for disability assistance; and society at large, which gains the productive skill of talented individuals

Bridging the digital divide for hard-to-reach groups

Boeltzig and Pilling identified specific groups of people who typically are not connected to the Internet and examined the circumstances of each - rural, poor, disabled, seniors, and ethnic minorities. They focused on how these groups of people, such as homebound individuals, could benefit most from using online government services. They also identified technical as well as social barriers that limit access. Their recommendations are aimed at both increasing access for these targeted groups and increasing use by individuals in the targeted groups. They also provide valuable recommendations aimed at service or application providers who have a major role in increasing both access and accessibility. The case studies resulted in insights and lessons that are broadly applicable. Based on the case studies, the authors offer recommendations that are practical and serve as useful guides to practitioners and policy makers at all levels of government