Temperature distribution in a stellar atmosphere diagnostic basis

A stellar chromosphere is considered a region where the temperature increases outward and where the temperature structure of the gas controls the shape of the spectral lines. It is shown that lines which have collision-dominated source sink terms, like the Ca(+) and Mg(+) H and K lines, can be used to obtain the distribution of temperature with height from observed line profiles. Intrinsic emission lines and geometrical emission lines are found in spectral regions where the continuum is depressed. In visual regions, where the continuum is not depressed, emission core in absorption lines are attributed to reflections of intrinsic emission lines

Coronal and chromospheric physics

Achievements and completed results are discussed for investigations covering solar activity during the solar maximum mission and the solar maximum year; other studies of solar activity and variability; infrared and submillimeter photometry; solar-related atomic physics; coronal and transition region studies; prominence research; chromospheric research in quiet and active regions; solar dynamics; eclipse studies; and polarimetry and magnetic field measurements. Contributions were also made in defining the photometric filterograph instrument for the solar optical telescope, designing the combined filter spectrograph, and in expressing the scientific aims and implementation of the solar corona diagnostic mission

Evidence of traffic-related pollutant control in soil-based Sustainable Urban Drainage Systems (SUDS)

SUDS are being increasingly employed to control highway runoff and have the potential to protect groundwater and surface water quality by minimising the risks of both point and diffuse sources of pollution. While these systems are effective at retaining polluted solids by filtration and sedimentation processes, less is known of the detail of pollutant behaviour within SUDS structures. This paper reports on investigations carried out as part of a co-ordinated programme of controlled studies and field measurements at soft-engineered SUDS undertaken in the UK, observing the accumulation and behaviour of traffic-related heavy metals, oil and PAHs. The field data presented were collected from two extended detention basins serving the M74 motorway in the south-west of Scotland. Additional data were supplied from an experimental lysimeter soil core leaching study. Results show that basin design influences pollutant accumulation and behaviour in the basins. Management and/or control strategies are discussed for reducing the impact of traffic-related pollutants on the aqueous environment

Playful interactions: A critical inquiry into interactive art and play

My practice-based doctoral research explores how I, as an artist, can create conditions and possibilities for playful interaction in and around interactive artworks. Using practice- based research methods four artworks were created, presented and examined in relation to my research questions concerning play. The three key research questions were:1] How do the properties and affordances of materials and technologies foster play and interactions?2] How can artists conceptualise physical participation and play in interactive artworks? 3] What kind of play takes place in and around interactive artwork?My inquiry focused on the development of a model for making playful and interactive artworks and the creation of a vocabulary of play, which demonstrates the different kinds of play initiated through my practice and research. The model provides alternative ways to think about the role of play within interactive art and consists of a series of tangible making gambits for eliciting playful interactions from the audience. The model will be useful for future interactive artists, as well as other fields concerned with the creation of playful experiences. Underpinning my process of creating playful experiences were methods of observation of the participants’ interactions, which were used in order to enable change and improvement of the artworks throughout the research process.I argue that by employing a sculptural approach to interactive art, using the visual arts tradition of working with the properties of materials and affordances of technology, an invitation to play was created. I propose that to focus on the material’s affordance, rather than on interactive systems, provides additional ways to create interactivity. I also suggest that by understanding technology as a sculptural and embodied material we can move the focus from the technology to what the art does and says. In this sculptural playful interactivity audience members are allowed and encouraged to touch and physical and immersive participation is invited. I explored the body as a particular mode of interaction that can bridge the divide between doing and looking in the gallery, developing theories of the playful body and how audiences connect through play. I argue that the combination of sculptural, captivating interfaces, where the artwork reacts reliably, enables the audience to develop play mastery and become fully engaged. These playful interactions invite people to be curious and seek to engage audiences into dialogue, thereby opening up the possibility for play. Play is an essential pre-condition for the emergence of possibilities and, as such, it is the flexible structure by which meaningful interaction can arise. These interactions are not about our relation to technology but rather about new ways of experiencing culture. In this context interactive art is part of a wider change in contemporary art, where artists are creating culture to be experienced rather than consumed

Predictability of large future changes in a competitive evolving population

The dynamical evolution of many economic, sociological, biological and physical systems tends to be dominated by a relatively small number of unexpected, large changes (`extreme events'). We study the large, internal changes produced in a generic multi-agent population competing for a limited resource, and find that the level of predictability actually increases prior to a large change. These large changes hence arise as a predictable consequence of information encoded in the system's global state.Comment: 10 pages, 3 figure

Mixed population Minority Game with generalized strategies

We present a quantitative theory, based on crowd effects, for the market volatility in a Minority Game played by a mixed population. Below a critical concentration of generalized strategy players, we find that the volatility in the crowded regime remains above the random coin-toss value regardless of the "temperature" controlling strategy use. Our theory yields good agreement with numerical simulations.Comment: Revtex file + 3 figure

Dynamical Solution of the On-Line Minority Game

We solve the dynamics of the on-line minority game, with general types of decision noise, using generating functional techniques a la De Dominicis and the temporal regularization procedure of Bedeaux et al. The result is a macroscopic dynamical theory in the form of closed equations for correlation- and response functions defined via an effective continuous-time single-trader process, which are exact in both the ergodic and in the non-ergodic regime of the minority game. Our solution also explains why, although one cannot formally truncate the Kramers-Moyal expansion of the process after the Fokker-Planck term, upon doing so one still finds the correct solution, that the previously proposed diffusion matrices for the Fokker-Planck term are incomplete, and how previously proposed approximations of the market volatility can be traced back to ergodicity assumptions.Comment: 25 pages LaTeX, no figure

Magnetoacoustic Portals and the Basal Heating of the Solar Chromosphere

We show that inclined magnetic field lines at the boundaries of large-scale convective cells (supergranules) provide "portals" through which low-frequency ( 5 mHz) acoustic waves, which are believed to provide the dominant source of wave heating of the chromosphere. This result opens up the possibility that low-frequency magnetoacoustic waves provide a significant source of energy for balancing the radiative losses of the ambient solar chromosphere