416 research outputs found
Argon and Silicon abundances in the damped Ly-alpha system I Zw 18
We show that the difference between the Ar and Si relative abundance ratio
derived from FUSE absorption spectra and from the HII regions of I Zw 18 is a
consequence of the microturbulent analysis applied to the absorption spectra.
FUSE observations were performed with a large entrance aperture which fully
covered the galaxy. This means that the observed profiles are averaged over the
full body of I Zw 18, implying that large-scale velocity fields influence the
absorption - line profiles. Taking this into account, we show that the
absorption spectra are consistent with the same metal abundances as those
derived from the HII regions. It follows that no significant ionization
correction as suggested by Izotov and collaborators to describe metal contents
in damped Ly-alpha systems (DLA) is required to model abundances in the neutral
gas of I Zw 18 (a local DLA system). Using a mesoturbulent approach and
applying the generalized radiative transfer equation to the ArI1048 and
SiII1020 lines observed by Vidal-Madjar et al., we found that the profiles may
be reproduced with log (Ar/Si) ~= - 0.8 and N(SiII) ~= 4 10^{15} cm^{-2}.Comment: 4 pages, 2 eps figure, submitted to A
Bringing Video Communication to the Community: Opportunities and Challenges
The rise of online social networks, the wide availability of video communication technology and the deployment of high-speed broadband networks together provide the opportunity for video to become a medium for mass social communication among communities. However, current solutions provide poor support for ad hoc social interactions among multiple groups of participants. This position paper summarises the results of more than 5 years’ research to make communication and engagement easier between groups of people separated in space. It shows how communication can be effectively combined with different shared activities, and how the technical capabilities of Communication Orchestration and Dynamic Composition work together to improve the quality of human interactions. The paper also describes ongoing work to develop the Service-Aware Network as a means of optimising the quality of a user’s communication experience while making most efficient use of network resources. We believe these developments could enable video-mediated communication to become an effective and accepted enabler for social communication within community groups globall
Process Mining IPTV Customer Eye Gaze Movement Using Discrete-time Markov Chains
Human-Computer Interaction (HCI) research has extensively employed eye-tracking technologies in a variety of fields. Meanwhile, the ongoing development of Internet Protocol TV (IPTV) has significantly enriched the TV customer experience, which is of great interest to researchers across academia and industry. A previous study was carried out at the BT Ireland Innovation Centre (BTIIC), where an eye tracker was employed to record user interactions with a Video-on-Demand (VoD) application, the BT Player. This paper is a complementary and subsequent study of the analysis of eye-tracking data in our previously published introductory paper. Here, we propose a method for integrating layout information from the BT Player with mining the process of customer eye movement on the screen, thereby generating HCI and Industry-relevant insights regarding user experience. We incorporate a popular Machine Learning model, a discrete-time Markov Chain (DTMC), into our methodology, as the eye tracker records each gaze movement at a particular frequency, which is a good example of discrete-time sequences. The Markov Model is found suitable for our study, and it helps to reveal characteristics of the gaze movement as well as the user interface (UI) design on the VoD application by interpreting transition matrices, first passage time, proposed ‘most likely trajectory’ and other Markov properties of the model. Additionally, the study has revealed numerous promising areas for future research. And the code involved in this study is open access on GitHub
Experiments with Distributed Theatre
The Tempest was probably the last play that Shakespeare wrote alone. It is unlikely that he would contemplate it being performed 400 years later, and
Absence of correlation between built-in electric dipole moment and quantum Stark effect in InAs/GaAs self-assembled quantum dots
We report significant deviations from the usual quadratic dependence of the
ground state interband transition energy on applied electric fields in
InAs/GaAs self-assembled quantum dots. In particular, we show that conventional
second-order perturbation theory fails to correctly describe the Stark shift
for electric field below kV/cm in high dots. Eight-band calculations demonstrate this effect is predominantly due to
the three-dimensional strain field distribution which for various dot shapes
and stoichiometric compositions drastically affects the hole ground state. Our
conclusions are supported by two independent experiments.Comment: 4 pages, 4 figure
Micellization of Sliding Polymer Surfactants
Following up a recent paper on grafted sliding polymer layers (Macromolecules
2005, 38, 1434-1441), we investigated the influence of the sliding degree of
freedom on the self-assembly of sliding polymeric surfactants that can be
obtained by complexation of polymers with cyclodextrins. In contrast to the
micelles of quenched block copolymer surfactants, the free energy of micelles
of sliding surfactants can have two minima: the first corresponding to small
micelles with symmetric arm lengths, and the second corresponding to large
micelles with asymmetric arm lengths. The relative sizes and concentrations of
small and large micelles in the solution depend on the molecular parameters of
the system. The appearance of small micelles drastically reduces the kinetic
barrier signifying the fast formation of equilibrium micelles.Comment: Submitted to Macromolecule
Distributed Theatre: Connecting (with) Remote Audiences
In September 2014, Miracle Theatre performed “the Tempest” simultaneously at two different locations to two separate audiences. Both audiences were linked together using an advanced video system, where several cameras captured the play. This is just one example of the radical shift in performing arts, where small theatre companies can use the Internet and a range of digital tools for reaching a wider remote audience. During the last years, we have explored how tele-presence has an effect on the performing arts, on the artists, and on the audiences. This p
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