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Supporting Computer-supported collaborative work (CSCW) in conceptual design
In order to gain a better understanding of online conceptual collaborative design processes this paper investigates how student designers make use of a shared virtual synchronous environment when engaged in conceptual design. The software enables users to talk to each other and share sketches when they are remotely located. The paper describes a novel methodology for observing and analysing collaborative design processes by adapting the concepts of grounded theory. Rather than concentrating on narrow aspects of the final artefacts, emerging “themes” are generated that provide a broader picture of collaborative design process and context descriptions. Findings on the themes of “grounding – mutual understanding” and “support creativity” complement findings from other research, while important themes associated with “near-synchrony” have not been emphasised in other research. From the study, a series of design recommendations are made for the development of tools to support online computer-supported collaborative work in design using a shared virtual environment
Object-Oriented Paradigms for Modelling Vascular\ud Tumour Growth: a Case Study
Motivated by a family of related hybrid multiscale models, we have built an object-oriented framework for developing and implementing multiscale models of vascular tumour growth. The models are implemented in our framework as a case study to highlight how object-oriented programming techniques and good object-oriented design may be used effectively to develop hybrid multiscale models of vascular tumour growth. The intention is that this paper will serve as a useful reference for researchers modelling complex biological systems and that these researchers will employ some of the techniques presented herein in their own projects
Optical sum rules that relate to the potential energy of strongly correlated systems
A class of sum rules for inelastic light scattering is developed. We show
that the first moment of the non-resonant response provides information about
the potential energy in strongly correlated systems. The polarization
dependence of the sum rules provide information about the electronic
excitations in different regions of the Brillouin zone. We determine the sum
rule for the Falicov-Kimball model, which possesses a metal-insulator
transition, and compare our results to the light scattering experiments in
SmB_6.Comment: (5 pages, 3 figures, typeset in ReVTeX
Observation of narrow-band noise accompanying the breakdown of insulating states in high Landau levels
Recent magnetotransport experiments on high mobility two-dimensional electron
systems have revealed many-body electron states unique to high Landau levels.
Among these are re-entrant integer quantum Hall states which undergo sharp
transitions to conduction above some threshold field. Here we report that these
transitions are often accompanied by narrow- and broad-band noise with
frequencies which are strongly dependent on the magnitude of the applied dc
current.Comment: 4 pages, 3 figure
Exact solutions for models of evolving networks with addition and deletion of nodes
There has been considerable recent interest in the properties of networks,
such as citation networks and the worldwide web, that grow by the addition of
vertices, and a number of simple solvable models of network growth have been
studied. In the real world, however, many networks, including the web, not only
add vertices but also lose them. Here we formulate models of the time evolution
of such networks and give exact solutions for a number of cases of particular
interest. For the case of net growth and so-called preferential attachment --
in which newly appearing vertices attach to previously existing ones in
proportion to vertex degree -- we show that the resulting networks have
power-law degree distributions, but with an exponent that diverges as the
growth rate vanishes. We conjecture that the low exponent values observed in
real-world networks are thus the result of vigorous growth in which the rate of
addition of vertices far exceeds the rate of removal. Were growth to slow in
the future, for instance in a more mature future version of the web, we would
expect to see exponents increase, potentially without bound.Comment: 9 pages, 3 figure
New Physics in High Landau Levels
Recent magneto-transport experiments on ultra-high mobility 2D electron
systems in GaAs/AlGaAs heterostructures have revealed the existence of whole
new classes of correlated many-electron states in highly excited Landau levels.
These new states, which appear only at extremely low temperatures, are
distinctly different from the familiar fractional quantum Hall liquids of the
lowest Landau level. Prominent among the recent findings are the discoveries of
giant anisotropies in the resistivity near half filling of the third and higher
Landau levels and the observation of re- entrant integer quantum Hall states in
the flanks of these same levels. This contribution will survey the present
status of this emerging field.Comment: 8 pages, 9 figures. To be published in the Proceedings of the 13th
International Conference on the Electronic Properties of Two-Dimensional
System
Motivation as a predictor of outcomes in school-based humanistic counselling
Recent years have seen a growth in the provision of counselling within UK secondary schools, and research indicates that it is associated with significant reductions in psychological distress. However, little is known about the moderators and mediators of positive therapeutic benefit. In the field of adult mental health, motivation has been found to be one of the strongest predictors of therapeutic outcomes, and it was hypothesised that this may also be a predictor of outcomes for young people in school-based counselling services. To assess the relationship between young people’s motivation for counselling and its effectiveness within a secondary school setting. Eighty-one young people (12 - 17 years old) who attended school-based humanistic counselling services in Scotland. Clients completed a measure of motivation for counselling at the commencement of their therapeutic work and a measure of psychological wellbeing at the commencement and termination of counselling. Motivation for counselling was not found to be significantly related to outcomes. The results indicate that the association between motivation and outcomes may be weaker in young people as compared with adults. However, a number of design factors may also account for the non-significant findings: insufficient participants, marginal reliability of the motivation measure and social desirability effects
Reply to Simon's Comment on "Evidence for an Anisotropic State of Two-Dimensional Electrons in High Landau Levels"
We recently reported [PRL 82, 394 (1999)] large transport anisotropies in a
two-dimensional electron gas in high Landau levels. These observations were
made utilizing both square and Hall bar sample geometries. Simon recently
commented [cond-mat/9903086] that a classical calculation of the current flow
in the sample shows a magnification of an underlying anisotropy when using a
square sample. In this reply we present more recent data obtained with a very
high mobility sample, and reiterate that, with or without magnification, an
anisotropic state develops in high Landau levels at very low temperatures.Comment: 1 page, 1 figur
Partial synchronisation of stochastic oscillators through hydrodynamic coupling
Holographic optical tweezers are used to construct a static bistable optical
potential energy landscape where a Brownian particle experiences restoring
forces from two nearby optical traps and undergoes thermally activated
transitions between the two energy minima. Hydrodynamic coupling between two
such systems results in their partial synchronisation. This is interpreted as
an emergence of higher mobility pathways, along which it is easier to overcome
barriers to structural rearrangement.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
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