913 research outputs found
Electronic transport in Si:P delta-doped wires
Despite the importance of Si:P delta-doped wires for modern nanoelectronics,
there are currently no computational models of electron transport in these
devices. In this paper we present a nonequilibrium Green's function model for
electronic transport in a delta-doped wire, which is described by a
tight-binding Hamiltonian matrix within a single-band effective-mass
approximation. We use this transport model to calculate the current-voltage
characteristics of a number of delta-doped wires, achieving good agreement with
experiment. To motivate our transport model we have performed
density-functional calculations for a variety of delta-doped wires, each with
different donor configurations. These calculations also allow us to accurately
define the electronic extent of a delta-doped wire, which we find to be at
least 4.6 nm.Comment: 13 pages, 11 figure
Finite-sided deformation spaces of complete affine 3-manifolds
A Margulis spacetime is a complete affine 3-manifold M with nonsolvable
fundamental group. Associated to every Margulis spacetime is a noncompact
complete hyperbolic surface S. We show that every Margulis spacetime is
orientable, even though S may be nonorientable. We classify Margulis spacetimes
when S is homeomorphic to a two-holed cross-surface, that is, the complement of
two disjoint discs in the real projective plane. We show that every such
manifold is homeomorphic to a solid handlebody of genus two, and admits a
fundamental polyhedron bounded by crooked planes. Furthermore, the deformation
space is a bundle of convex quadrilateral cones over the space of marked
hyperbolic structures. The sides of each quadrilateral cone are defined by
invariants of the two boundary components and the two orientation-reversing
simple curves. The two-holed cross-surface, together with the three-holed
sphere, are the only topologies for which the deformation space of complete
affine structures is finite-sided.Comment: 29 pages, 8 figures. Accepted for publication in the Journal of
Topolog
Through Christ Alone?: Adventists’ Beliefs about Salvation
This presentation examines how Adventists from four world divisions view the issue of salvation. Using data from the 2018 and 2023 Global Church Member’s Surveys, we compare and contrast members’ stated beliefs over time about how one receives salvation. The analysis includes cultural factors that may be influencing these outcomes
A pan-European valuation of the extent, causes and cost of escape events from sea cage fish farming
As part of an EU funded 7th Framework project, Prevent Escape, a programme of research was undertaken to document the extent, size and knowledge of the causes of escapes from marine fin fish farms in Europe over a three year period. Escape incidents were identified and assessed through questionnaires across the 6 countries (Ireland, UK, Norway, Spain, Greece, and Malta), and other data supplied by the Norwegian Fisheries Directorate and the Scottish Aquaculture Research Forum. A total of 8,922,863 fish were reported to have escaped from 242 incidents. Of these over 5 million occurred in two catastrophic escape incidents. Sea bream accounted for the highest number of escapes at 76.7% followed by Atlantic salmon at 9.2%. Of the 113 Atlantic salmon escape events, almost 75% were due to structure failure or operational error. Almost 50% of cod escape incidents were due to biological causes e.g. biting of nets. The nominal costs of escapes as calculated by value at point of first sale were very substantial, estimated at approximately €47.5 million per annum on average over the study period. Of this €42.8 million was for annual cost of losses of sea bass and sea bream in the Mediterranean and €4.7 million for losses of salmon in northern Europe.peer-reviewe
The Aeolus project : science outreach through art
With a general decline in people’s choosing to pursue science and engineering degrees there has never been a greater need to raise the awareness of lesser known fields such as acoustics. Given this context, a large-scale public engagement project, the ‘Aeolus project’, was created to raise awareness of acoustics science through a major collaboration between an acclaimed artist and acoustics researchers. It centred on touring the large singing sculpture Aeolus during 2011/12, though the project also included an extensive outreach programme of talks, exhibitions, community workshops and resources for schools. Described here are the motivations behind the project and the artwork itself, the ways in which scientists and an artist collaborated, and the public engagement activities designed as part of the project. Evaluation results suggest that the project achieved its goal of inspiring interest in the discipline of acoustics through the exploration of an otherworldly work of art
- …