Building an alternative social currency: Dematerialising and rematerialising digital money across media

This paper reports on the user experience and design of physical and digital forms of a mixed-media local currency. We reconceive digitally mediated transactions as social interactions and report on the development of conceptual designs informed by user research and interactive workshops. Our findings show that use is strongly tied to conceptions of locality and community, markers of identity, information exchange and the digital and physical forms as tools for shaping interactions. The form of the currency can make the invisible visible, exposing our identities and values, business models, and the details of the transactions themselves. Our analysis stresses the need to provide opportunities for extending social interaction, making more local connections and deriving the best value from those connections, without insulating individuals from each other, or from the wider geographical context. Themes that emerged from the user research were visualized as conceptual designs for digitally augmented media, allowing us to explore the monetary transaction at three levels: the material, as interaction between two parties, and the context of the transaction.The RCUK Digital Economy theme (EP/K012304/1)

The radial structure of protostellar accretion disks: influence of jets

The radial structure of accretion disks is a fundamental issue regarding star and planet formation. Many theoretical studies, focussing on different aspects such as e.g. disk emissivity or ionization, have been conducted in the context of the Standard Accretion Disk (SAD) model, where no jet is present. We wish to calculate the structure of YSO accretion disks in an approach that takes into account the presence of the protostellar jets. The radial structure of these Jet Emitting Disks (JED) should then be compared to that of standard accretion disks. The analytical treatment used in this work is very similar to that of standard accretion disks but is using the parameter space of Magnetised Accretion-Ejection Structures that include the jet torque on the underlying disk. In this framework, the analytical expressions of key quantities, such as mid-plane temperatures, surface densities or disk aspect ratio are derived. It is found that JEDs present a structure very different from the SADs and that can be observationally tested. The implications on planet formation in the inner regions of accretion disks are briefly discussed. We also supply sets of analytical formulae, valid in different opacity regimes, for the disk quantities. These expressions can be readily used for any work where the disk structure is needed as an input for the model.Comment: 11 pages, 4 figures. Accepted for publication in A&

Are Magnetic Wind-Driving Disks Inherently Unstable?

There have been claims in the literature that accretion disks in which a centrifugally driven wind is the dominant mode of angular momentum transport are inherently unstable. This issue is considered here by applying an equilibrium-curve analysis to the wind-driving, ambipolar diffusion-dominated, magnetic disk model of Wardle & Konigl (1993). The equilibrium solution curves for this class of models typically exhibit two distinct branches. It is argued that only one of these branches represents unstable equilibria and that a real disk/wind system likely corresponds to a stable solution.Comment: 5 pages, 2 figures, to be published in ApJ, vol. 617 (2004 Dec 20). Uses emulateapj.cl

Interpreting infrastructure: Defining user value for digital financial intermediaries.

The 3DaRoC project is exploring digital connectivity and peer-to-peer relationships in financial services. In the light of the near collapse of the UK and world financial sector, understanding and innovating new and more sustainable approaches to financial services is now a critical topic. At the same time, the increasing penetration and take-up of robust high-speed networks, dependable peerto- peer architectures and mobile multimedia technologies offer novel platforms for offering financial services over the Internet. These new forms of digital connectivity give rise to opportunities in doing financial transactions in different ways and with radically different business models that offer the possibility of transforming the marketplace. One area in the digital economy that has had such an effect is in the ways that users access and use digital banking and payment services. The impact of the new economic models presented by these digital financial services is yet to be fully determined, but they have huge potential as disruptive innovations, with a potentially transformative effect on the way that services are offered to users. Little is understood about how technical infrastructures impact on the ways that people make sense of the financial services that they use, or on how these might be designed more effectively. 3DaRoC is exploring this space working with our partners and end users to prototype and evaluate new online, mobile, ubiquitous and tangible technologies, exploring how these services might be extended.Executive Summary: Drawing from Studies of Use - the value, use and interpretation of infrastructure in digital intermediaries to their users. The UK economy has a huge dependence on financial services, and this is increasingly based on digital platforms. Innovating new economic models around consumer financial services through the use of digital technologies is seen as increasingly important in developed economies. There are a number of drivers for this, ranging from national economic factors to the prosaic nature of enabling cheap, speedy and timely interactions for users. The potential for these new digital solutions is that they will allay an over-reliance on the traditional banking sector, which has proved itself to be unstable and risky, and we have seen a number of national policy moves to encourage growth in this sector. Partly as a result of the 2008 banking crisis, there has been an explosion in peer-to-peer financial services for non-professional consumers. These organisations act as intermediaries between users looking to trade goods or credit. However, building self-sustaining or profitable financial services within this novel space is itself fraught with commercial, regulatory, technical and social problems. This document reports on the value, use and interpretation of infrastructure in digital intermediaries to their users, describing analysis of contextual field studies carried out in two retail digital financial intermediary organisations: Zopa Limited and the Bristol Pound. It forms the second milestone document in the 3DaRoC project, developing patterns of use that have arisen on the back of the technical infrastructures in the two organisations that form cases for examination. Its purpose is to examine how the two different technical infrastructures that underpin the transactions that they support–composed of the back-office hardware and software, data structures, the networking and communications technologies used, supported consumer devices, and the user interfaces and interaction design–have provided opportunities for users to realise their financial and other needs. While we orient towards the issues of service use (and its problems), we also examine the activities and expectations of their various users. Our research has involved teams from Lancaster University examining Zopa and Brunel University focusing on the Bristol Pound over approximately a one-year period from October 2013 to October 2014. Extensive interviews, document analysis, observation of user interactions, and other methods have been employed to develop the process analyses of the firms presented here. This report comprises of three key sections: descriptions of the user demographics for Zopa and the Bristol Pound, a discussion about the user experience and its role in community, and an examination of the role of usage data in the development of these a products. We conclude with final analytical section drawing preliminary conclusions from the research presented.The 3DaRoC project is funded by the RCUK Digital Economy ‘Research in the Wild’ theme (grant no. EP/K012304/1)

Many-body effects on the ρxx\rho_{xx} ringlike structures in two-subband wells

The longitudinal resistivity $\rho_{xx}$ of two-dimensional electron gases formed in wells with two subbands displays ringlike structures when plotted in a density--magnetic-field diagram, due to the crossings of spin-split Landau levels (LLs) from distinct subbands. Using spin density functional theory and linear response, we investigate the shape and spin polarization of these structures as a function of temperature and magnetic-field tilt angle. We find that (i) some of the rings "break" at sufficiently low temperatures due to a quantum Hall ferromagnetic phase transition, thus exhibiting a high degree of spin polarization ($\sim 50$%) within, consistent with the NMR data of Zhang \textit{et al.} [Phys. Rev. Lett. {\bf 98}, 246802 (2007)], and (ii) for increasing tilting angles the interplay between the anticrossings due to inter-LL couplings and the exchange-correlation (XC) effects leads to a collapse of the rings at some critical angle $\theta_c$, in agreement with the data of Guo \textit{et al.} [Phys. Rev. B {\bf 78}, 233305 (2008)].Comment: 4 pages, 3 figure

Magnetic braking in young late-type stars: the effect of polar spots

The concentration of magnetic flux near the poles of rapidly rotating cool stars has been recently proposed as an alternative mechanism to dynamo saturation in order to explain the saturation of angular momentum loss. In this work we study the effect of magnetic surface flux distribution on the coronal field topology and angular momentum loss rate. We investigate if magnetic flux concentration towards the pole is a reasonable alternative to dynamo saturation. We construct a 1D wind model and also apply a 2-D self-similar analytical model, to evaluate how the surface field distribution affects the angular momentum loss of the rotating star. From the 1D model we find that, in a magnetically dominated low corona, the concentrated polar surface field rapidly expands to regions of low magnetic pressure resulting in a coronal field with small latitudinal variation. We also find that the angular momentum loss rate due to a uniform field or a concentrated field with equal total magnetic flux is very similar. From the 2D wind model we show that there are several relevant factors to take into account when studying the angular momentum loss from a star. In particular, we show that the inclusion of force balance across the field in a wind model is fundamental if realistic conclusions are to be drawn from the effect of non-uniform surface field distribution on magnetic braking. This model predicts that a magnetic field concentrated at high latitudes leads to larger Alfven radii and larger braking rates than a smoother field distribution. From the results obtained, we argue that the magnetic surface field distribution towards the pole does not directly limit the braking efficiency of the wind.Comment: 11 pages, 10 figures, accepted in A&

#CHIMoney: Financial interactions, digital cash, capital exchange and mobile money

Interactions around money and financial services are a critical part of our lives on and off-line. New technologies and new ways of interacting with these technologies are of huge interest; they enable new business models and ways of making sense of this most important aspect of our everyday lives. At the same time, money is an essential element in HCI research and design. This workshop is intended to bring together researchers and practitioners involved in the design and use of systems that combine digital and new media with monetary and financial interactions to build on an understanding of these technologies and their impacts on users' behaviors. The workshop will focus on social, technical, and economic aspects around everyday user interactions with money and emerging financial technologies and systems

Putting the ‘digital’ in Digital Intermediaries: the role of technical infrastructure in building business models

Digital Technology Innovation and Financial Business Practices The UK economy has a huge dependence on financial services, and this is increasingly based on digital platforms. Innovating new economic models around consumer financial services through the use of digital technologies is seen as increasingly important in developed economies. There are a number of drivers for this, ranging from national economic factors to the prosaic nature of enabling cheap, speedy and timely interactions for users. The potential for these new digital solutions is that they will allay an over-reliance on the traditional banking sector, which has proved itself to be unstable and risky, and we have seen a number of national policy moves to encourage growth in this sector. Partly as a result of the 2008 banking crisis, there has been an explosion in peer-to-peer financial services for non-professional consumers. These organisations act as intermediaries between users looking to trade goods or credit. However, building self-sustaining or profitable financial services within this novel space is itself fraught with commercial, regulatory, technical and social problems. This report addresses the mutual shaping of business models and innovations in digital technical infrastructure – both client-facing and administrative back-end – in two retail financial products currently in use in the United Kingdom: peer-to-peer consumer lending and a local digital/paper hybrid currency system. The two products and their issuing firms, Zopa Limited (Zopa) and The Bristol Pound Community Interest Company (the Bristol Pound), respectively, are established leaders in their respective product areas: Zopa was established in 2005 and the Bristol Pound in 2010. Each of these firms seeks to disrupt an established financial market through the application of digital technologies and processes: consumer lending for Zopa and retail payment for the Bristol Pound. Our research has involved teams from Lancaster University examining Zopa and Brunel University focusing on the Bristol Pound over approximately a one-year period from October 2013 to October 2014. Extensive interviews, document analysis, observation of user interactions, and other methods have been employed to develop the process analyses of the firms presented here. This report is comprised of three primary sections: descriptions of the business and technological processes of each of Zopa and the Bristol Pound, and a final analytical section drawing preliminary conclusions from the research presented.3DaRoC is funded by the UK’s Digital Economy ‘Research in the Wild’ initiative. It has a substantial research budget of over £320K, with £35K of additional industrial support

Magnetically Defined Qubits on 3D Topological Insulators

We explore potentials that break time-reversal symmetry to confine the surface states of 3D topological insulators into quantum wires and quantum dots. A magnetic domain wall on a ferromagnet insulator cap layer provides interfacial states predicted to show the quantum anomalous Hall effect (QAHE). Here we show that confinement can also occur at magnetic domain heterostructures, with states extended in the inner domain, as well as interfacial QAHE states at the surrounding domain walls. The proposed geometry allows the isolation of the wire and dot from spurious circumventing surface states. For the quantum dots we find that highly spin-polarized quantized QAHE states at the dot edge constitute a promising candidate for quantum computing qubits.Comment: 5 pages, 4 figure