810 research outputs found
Supporting Community Participation in Interactive Exhibits
We describe the Byker Lives Table, an interactive installation that aimed to support user-contributed content in an exhibition of community history around a landmark housing development. As both the history of the development and subsequent social problems in the area are contentious issues, we aimed to support discussion around content that might mean very different things to different people. Based on a yearlong deployment, we reflect on the exhibit in terms of its ability to support community participation, create dialogue representing multiple perspectives on the content and allow lightweight curation
Structure and deformations of strongly magnetized neutron stars with twisted torus configurations
We construct general relativistic models of stationary, strongly magnetized
neutron stars. The magnetic field configuration, obtained by solving the
relativistic Grad-Shafranov equation, is a generalization of the twisted torus
model recently proposed in the literature; the stellar deformations induced by
the magnetic field are computed by solving the perturbed Einstein's equations;
stellar matter is modeled using realistic equations of state. We find that in
these configurations the poloidal field dominates over the toroidal field and
that, if the magnetic field is sufficiently strong during the first phases of
the stellar life, it can produce large deformations.Comment: 10 pages, 5 figures. Minor changes to match the version published on
MNRA
Evocative computing – creating meaningful lasting experiences in connecting with the past
We present an approach – evocative computing – that demonstrates how ‘at hand’ technologies can be ‘picked up’ and used by people to create meaningful and lasting experiences, through connecting and interacting with the past. The approach is instantiated here through a suite of interactive technologies configured for an indoor-outdoor setting that enables groups to explore, discover and research the history and background of a public cemetery. We report on a two-part study where different groups visited the cemetery and interacted with the digital tools and resources. During their activities serendipitous uses of the technology led to connections being made between personal memo-ries and ongoing activities. Furthermore, these experiences were found to be long-lasting; a follow-up study, one year later, showed them to be highly memorable, and in some cases leading participants to take up new directions in their work. We discuss the value of evocative computing for enriching user experiences and engagement with heritage practices
Cultural heritage communities: Technologies and challenges
This workshop will explore the role of technology support-ing and mediating cultural heritage practices for both pro-febional communities (cultural heritage profebionals, her-itage institutions, etc.) and civic communities (citizen-led heritage initiatives, heritage volunteers, personal and com-munity identified heritage, heritage crowdsourcing, etc.). The workshop-which aims to attract participants from her-itage studies and practice, community engagement, digital humanities and human-centred computing-will discub challenges and future opportunities for technology use and for design and participatory procebes in the context of var-ious heritage communities, and the role of different stake-holders in engaging with heritage in a technologically-mediated way
Implementing a new recovery scheme for primitive variables in the general relativistic magnetohydrodynamic code Spritz
General relativistic magnetohydrodynamic (GRMHD) simulations represent a fundamental tool to probe various underlying mechanisms at play during binary neutron star (BNS) and neutron star (NS) - black hole (BH) mergers. Contemporary flux-conservative GRMHD codes numerically evolve a set of conservative equations based on `conserved' variables which then need to be converted back into the fundamental (`primitive') variables. The corresponding conservative-to-primitive variable recovery procedure, based on root-finding algorithms, constitutes one of the core elements of such GRMHD codes. Recently, a new robust, accurate and efficient recovery scheme called RePrimAnd was introduced, which has demonstrated the ability to always converge to a unique solution. The scheme provides fine-grained error policies to handle invalid states caused by evolution errors, and also provides analytical bounds for the error of all primitive variables. In this work, we describe the technical aspects of implementing the RePrimAnd scheme into the GRMHD code Spritz. To check our implementation as well as to assess the various features of the scheme, we perform a number of GRMHD tests in three dimensions. Our tests, which include critical cases such as a NS collapse to a BH as well as the early evolution (~50 ms) of a Fishbone-Moncrief BH-accrection disk system, show that RePrimAnd is able to support magnetized, low density environments with magnetic-to-fluid pressure ratios as high as 10^4, in situations where the previously used recovery scheme fails
Designing for digital wellbeing: A research & practice agenda
Traditionally, many consumer-focused technologies have been designed to maximize user engagement with their products and services. More recently, many technology companies have begun to introduce digital wellbeing features, such as for managing time spent and for encouraging breaks in use. These are in the context of, and likely in response to, renewed concerns in the media about technology dependency and even addiction. The promotion of technology abstinence is also increasingly widespread, e.g., via digital detoxes. Given that digital technologies are an important and valuable feature of many people's lives, digital wellbeing features are arguably preferable to abstinence
Relativistic models of magnetars: the twisted-torus magnetic field configuration
We find general relativistic solutions of equilibrium magnetic field
configurations in magnetars, extending previous results of Colaiuda et al.
(2008). Our method is based on the solution of the relativistic Grad-Shafranov
equation, to which Maxwell's equations can be reduced in some limit. We obtain
equilibrium solutions with the toroidal magnetic field component confined into
a finite region inside the star, and the poloidal component extending to the
exterior. These so-called twisted-torus configurations have been found to be
the final outcome of dynamical simulations in the framework of Newtonian
gravity, and appear to be more stable than other configurations. The solutions
include higher order multipoles, which are coupled to the dominant dipolar
field. We use arguments of minimal energy to constrain the ratio of the
toroidal to the poloidal field.Comment: 13 pages, 12 figures. Minor changes to match the version published on
MNRA
Ambipolar diffusion in superfluid neutron stars
In this paper we reconsider the problem of magnetic field diffusion in
neutron star cores. We model the star as consisting of a mixture of neutrons,
protons and electrons, and allow for particle reactions and binary collisions
between species. Our analysis is in much the same spirit as that of Goldreich &
Reisenegger (1992), and we content ourselves with rough estimates of magnetic
diffusion timescales, rather than solving accurately for some particular field
geometry. However, our work improves upon previous treatments in one crucial
respect: we allow for superfluidity in the neutron star matter. We find that
the consequent mutual friction force, coupling the neutrons and charged
particles, together with the suppression of particles collisions and reactions,
drastically affect the ambipolar magnetic field diffusion timescale. In
particular, the addition of superfluidity means that it is unlikely that there
is ambipolar diffusion in magnetar cores on the timescale of the lifetimes of
these objects, contradicting an assumption often made in the modelling of the
flaring activity commonly observed in magnetars. Our work suggests that if a
decaying magnetic field is indeed the cause of magnetar activity, the field
evolution is likely to take place outside of the core, and might represent
Hall/Ohmic diffusion in the stellar crust, or else that a mechanism other than
standard ambipolar diffusion is active, e.g. flux expulsion due to the
interaction between neutron vortices and magnetic fluxtubes.Comment: Paper changed to incorporate comments from referee. To appear in
MNRA
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