Older adults, falls and technologies for independent living: a life space approach

This paper draws attention to the need for further understanding of the fine details of routine and taken-for-granted daily activities and mobility. It argues that such understanding is critical if technologies designed to mitigate the negative impacts of falls and fear-of-falling are to provide unobtrusive support for independent living. The reported research was part of a large, multidisciplinary, multi-site research programme into responses to population ageing in Ireland, Technologies for Independent Living (TRIL). A small, exploratory, qualitative life-space diary study was conducted. Working with eight community-dwelling older adults with different experiences of falls or of fear-of-falls, data were collected through weekly life-space diaries, daily-activity logs, two-dimensional house plans and a pedometer. For some participants, self-recording of their daily activities and movements revealed routine, potentially risky behaviour about which they had been unaware, which may have implications for falls-prevention advice. The findings are presented and discussed around four key themes: ‘being pragmatic’, ‘not just a faller’, ‘heightened awareness and blind spots’ and ‘working with technology’. The findings suggest a need to think creatively about how technological and other solutions best fit with people's everyday challenges and needs and of critical importance, that their installation does not reduce an older adult to ‘just a faller’ or a person with a fear-of-falls

Formalising behaviour trees with CSP

Behaviour Trees is a novel approach for requirements engineering. It advocates a graphical tree notation that is easy to use and to understand. Individual requirements axe modelled as single trees which later on are integrated into a model of the system as a whole. We develop a formal semantics for a subset of Behaviour Trees using CSP. This work, on one hand, provides tool support for Behaviour Trees. On the other hand, it builds a front-end to a subset of the CSP notation and gives CSP users a new modelling strategy which is well suited to the challenges of requirements engineering

Harmonic Generation from Relativistic Plasma Surfaces in Ultra-Steep Plasma Density Gradients

Harmonic generation in the limit of ultra-steep density gradients is studied experimentally. Observations demonstrate that while the efficient generation of high order harmonics from relativistic surfaces requires steep plasma density scale-lengths ($L_p/\lambda < 1$) the absolute efficiency of the harmonics declines for the steepest plasma density scale-length $L_p \to 0$, thus demonstrating that near-steplike density gradients can be achieved for interactions using high-contrast high-intensity laser pulses. Absolute photon yields are obtained using a calibrated detection system. The efficiency of harmonics reflected from the laser driven plasma surface via the Relativistic Oscillating Mirror (ROM) was estimated to be in the range of 10^{-4} - 10^{-6} of the laser pulse energy for photon energies ranging from 20-40 eV, with the best results being obtained for an intermediate density scale-length

Enhanced proton flux in the MeV range by defocused laser irradiation

Thin Al foils (50 nm and 6 mu m) were irradiated at intensities of up to 2x10(19) W cm(-2) using high contrast (10(8)) laser pulses. Ion emission from the rear of the targets was measured using a scintillator-based Thomson parabola and beam sampling 'footprint' monitor. The variation of the ion spectra and beam profile with focal spot size was systematically studied. The results show that while the maximum proton energy is achieved around tight focus for both target thicknesses, as the spot size increases the ion flux at lower energies is seen to peak at significantly increased spot sizes. Measurements of the proton footprint, however, show that the off-axis proton flux is highest at tight focus, indicating that a previously identified proton deflection mechanism may alter the on-axis spectrum. One-dimensional particle-in-cell modelling of the experiment supports our hypothesis that the observed change in spectra with focal spot size is due to the competition of two effects: decrease in laser intensity and an increase in proton emission area