The energy operator for infinite statistics

We construct the energy operator for particles obeying infinite statistics defined by a q-deformation of the Heisenberg algebra. (This paper appeared published in CMP in 1992, but was not archived at the time.)Comment: 6 page

Non-linear optics with two trapped atoms

We show theoretically that two atomic dipoles in a resonator constitute a non-linear medium, whose properties can be controlled through the relative position of the atoms inside the cavity and the detuning and intensity of the driving laser. We identify the parameter regime where the system operates as a parametric amplifier, based on the cascade emission of the collective dipole of the atoms, and determine the corresponding spectrum of squeezing of the field at the cavity output. This dynamics could be observed as a result of self-organization of laser-cooled atoms in resonators.Comment: 11 pages, 8 figure

Study of the spatial variation of the biodegradation rate of the herbicide bentazone with soil depth using contrasting incubation methods

Vertical and horizontal spatial variability in the biodegradation of the herbicide bentazone was compared in sandy-loam soil from an agricultural field using sieved soil and intact soil cores. An initial experiment compared degradation at five depths between 0 and 80 cm using sieved soil. Degradation was shown to follow the first-order kinetics, and time to 50% degradation (DT50), declined progressively with soil depth from 56 d at 0–10 cm to 520 d at 70–80 cm. DT50 was significantly correlated with organic matter, pH and dehydrogenase activity. In a subsequent experiment, degradation rate was compared after 127 d in sieved soil and intact cores from 0 to 10 and 50 to 60 cm depth from 10 locations across a 160 × 90 m portion of the field. Method of incubation significantly affected mean dissipation rate, although there were relatively small differences in the amount of pesticide remaining in intact cores and sieved soil, accounting for between 4.6% and 10.6% of that added. Spatial variability in degradation rate was higher in soil from 0 to 10 cm depth relative to that from 50 and 60 cm depth in both sieved soil and intact core assessments. Patterns of spatial variability measured using cores and sieved soil were similar at 50–60 cm, but not at 0–10 cm depth. This could reflect loss of environmental context following processing of sieved soil. In particular, moisture content, which was controlled in sieved soil, was found to be variable in cores, and was significantly correlated with degradation rate in intact topsoil cores from 0 to 10 cm depth

Motivations to volunteer in selected service organisations in Australia

The contributions of volunteers assist many organisations to stretch scarce resources further in a bid to provide important services to the community. Such organisations are challenged to motivate the participation of new and continuing volunteers. Although most people in the community recognise the value and importance of volunteerism, few actually commit to participating as volunteers. This study seeks to expand the somewhat limited research on volunteers in an Australian context. The sample consisted of 361 volunteers from three service organisations in Australia-- Rotary International, Horne and Community Care (HACC), and Surf Life Saving Australia. Each of these groups fulfils an important role in the community, yet struggles to recruit and retain the services of volunteers. Determining the motivations that members and potential members seek to have satisfied through their volunteer participation allows persuasive communication to be developed that will more effectively attract people to these organisations. It can also assist the placement of volunteers in the most satisfying roles, resulting in longer retention of volunteers. This study employed the Volunteer Functions Inventory (VFI), an instrument that measures the motivational profile of individual volunteers. The reasonable sample size facilitated the use of multivariate techniques such as factor, discriminant, and cluster analysis, Motivational and demographic profiles of the sample and each sub-group were determined and differences between the three sub-groups examined. The results determined that, for this sample, there were five key motivations to volunteer, contrasting with the six-factor result consistently found by the developers of the VFI. Further research is required to determine whether this is a reflection of Australian volunteers or rather of this particular sample. For the total sample and for each sub-group, the primary motivators of their volunteer participation were the Values and Understanding functions, and the Career function was the least important motivation. The Career motive was, however, significantly more important for Surf Life Saving volunteers than for the Rotary and HACC volunteers and served to differentiate between the groups. The results suggested that Surf Life Saving volunteers tended to be more egoistically-oriented in their motivations for volunteering than were the Rotary and HACC volunteers. Implications for the recruitment, placement and retention of volunteers in these organisations are subsequently discussed

Resonant tunneling in a schematic model

Tunneling of an harmonically bound two-body system through an external Gaussian barrier is studied in a schematic model which allows for a better understanding of intricate quantum phenomena. The role of finite size and internal structure is investigated in a consistent treatment. The excitation of internal degrees of freedom gives rise to a peaked structure in the penetration factor. The model results indicate that for soft systems the adiabatic limit is not necessarily reached although often assumed in fusion of nuclei and in electron screening effects at astrophysical energies.Comment: 7 pages, 7 figure