Re-composing the digital present

This paper investigates the temporality that is produced in some recent and historical examples of media art. In exploring works by Janet Cardiff, Dennis Del Favero, and Omer Fast, I use the philosophy of Michel Serres and Gilles Deleuze to understand the convergence of temporalities that are composed in the digital present, as one moment in time overlays another moment. Developing Serres' concept of multi-temporality and Deleuze's philosophy of time and memory into a means to understand the non-linear time presented in these works, I argue that the different compositional strategies enacted by these artists provide the aesthetic grounding to experience “temporal thickness.” From here I investigate the interactive digital artworks Frames by Grahame Weinbren and Can You See Me Now? by the artist group Blast Theory. In this investigation, I understand interaction with technology, and the way that it shapes our sensory and processual experience, as a specifically temporal and temporalizing transaction, where human movements in the present are overlayed by technological processes

Measuring the Affordances of Studying in a Virtual World

There has been much interest at the University of Hertfordshire in the teaching and learning in virtual worlds such as Second Life. The School of Computer Science has established a virtual campus within this system where a broad range of learning and teaching activities take place. These include presenting textual, audio and video learning and teaching materials, delivering virtual lectures, providing simulations and group working areas. Recently there has been a great deal of controversy over such initiatives, for example at my own university lecturers are divided as to the efficacy of such an approach. Some see the initiative as an interesting addition to the range of teaching and learning strategies available, likely to motivate learners. Others see it as a trivial attempt to jump on the latest band wagon, with little pedagogical benefit or justification. My own past research in this area, over several years has related to an estimation of the cognitive load imposed by desktop virtual environments and how this affected learning. Several important variables have been identified in several years of research and their effects measured. In the study presented here, a group of 80 final year computer science students used the Second Life virtual environment in order to support their practical project work. Groups of four learners used the university virtual campus especially modified for this purpose to hold meetings and to manage their software development projects. This study reports on how the group areas were established and used by the learners, the types of activities that took place and the effectiveness of the approach in this context. Quantitative and qualitative research was undertaken and it was found that there were benefits to be had by the use of such virtual environments. Recommendations are made as to the affordances of the Second Life virtual environment for teaching and learning in this context and also discussed are the potential problems inherent in this initiative related to individual differences and the cognitive burden imposed on learners.Peer reviewe

The ionization structure of planetary nebulae. 4: NGC 6853

Spectrophotometric observations of emission line intensities were made in seven positions in the planetary nebula NGC 6853; for five of the positions, coverage is across the entire spectral range 1400A to 9600A. Standard equations used to correct for the existence of elements in other than the optically-observable ionization stages give results over a wide range of ionization that are generally consistent and in agreement with abundances calculated using ultraviolet lines. As in the previous studies in this series, the lambda 4267 CII line implies a c(2+) abundance that is higher than that determined from UV lines. Although this effect is much smaller than in NGC 6720 and NGC 7009, it is again largest nearest the central star, giving more evidence that the excitation mechanism for the lambda 4267 line is not understood

The ionization structure of planetary nebulae. 3: NGC 7009

Spectrophotometric observations of emission line intensities were made in 8 positions in the planetary nebula NGC 7009. For the 6 brightest positions, the coverage is from 1400 A to 10,000 A. Standard equations used to correct for the existence of elements in other than the optical observable ionization stages give results over a wide range of ionization that are consistent and agree with abundances calculated using ultraviolet lines. This result is particularly gratifying for N because previously the standard formula gave inconsistent abundances in NGC 7009. The major outstanding problem is that the lambda 4267 CII line implies a C(2+) abundance as much as 12 times greater than that determined from the UV lines. This discrepancy is greatest nearest the central star, as is the case in the planetary nebula NGC 6720. The logarithmic abundances (relative to H=12.00) are: He=11.07, 0=8.68, N=8.10, Ne=8.16, C=8.18, Ar=6.36, and S=7.12. The average of the Ne, Ar, and S abundances agrees to within 5% of that for NGC 6720, but the O, N, nd C abundances average 1.9 times lower in NGC 7009, suggesting that here may have been mixing of processed material in the planetary precursor in NGC 6720

The ionization structure of planetary nebulae. Part 4: NGC 7662

Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 7200 A were made in five positions in the planetary nebula NGC 7662. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages show a consistent and approximate agreement with abundances calculated using ultraviolet lines. The abundances of C and N indicate that some mixing of CNO-processed material into the nebular shell may have occurred in NGC 7662; the low He abundance, however, indicates that little or no He enrichment occurred. The Ar, Ne, and O and S abundances appear to be low. It is suggested that the progenitor to NGC 7662 may have formed out of somewhat metal-poor material

The ionization structure of planetary nebulae V NGC 3242

Spectrophotometric observations of emission line intensities over the spectral range 1400 A to 9600 A were made in five positions in the planetary nebula NGC 3242. In two of the positions, both the weakness of the 1548 A, 1550 A C IV resonance lines and the steepness of the Balmer decrement suggest the possibility of internal dust in the nebula. The measured electron temperature varies little from the average value of 11,100 K, which is in reasonably good agreement with the less accurate value of 12,900 K measured from the Balmer continuum. The 4267 A C II line implies a C(2+) abundance that is much higher than that determined from the 1906 A, 1908 A C III lines. This discrepancy decreases with increasing distance from the central star. Equations used to correct for the existence of elements in other than the optically-observable ionization stages give results that are consistent and in agreement with abundances calculated using ultraviolet lines. This discrepancy decreases with increasing distance from the central star. Equations used to correct for the existence of elements in other than the optically-observable ionization stages give results that are consistent and in agreement with abundances calculated using ultraviolet lines. The logarithmic abundances are He=10.96, 0=8.64, N=7.96, Ne=8.04, C=8.41, Ar=6.15, and S=6.51