25,519 research outputs found
Surface Plasmons and Topological Insulators
We study surface plasmons localized on interfaces between topologically
trivial and topologically non-trivial time reversal invariant materials in
three dimensions. For the interface between a metal and a topological insulator
the magnetic polarization of the surface plasmon is rotated out of the plane of
the interface; this effect should be experimentally observable by exciting the
surface plasmon with polarized light. More interestingly, we argue that the
same effect also is realized on the interface between vacuum and a doped
topological insulator with non-vanishing bulk carrier density.Comment: 6 pages, 1 figure; v2: typo in eq. (27) correcte
Integrated Infrastructure Modelling — Managing Interdependencies with a Generic Approach
Infrastructure provision is a highly challenging task, especially when accounting for climate change mitigation and adaptation
needs. Efforts of making infrastructure more efficient and flexible result in an increasing number of sensitive infrastructure
interdependencies. This enforces an integrated infrastructure assessment for planning purposes, in contrast to the traditional
independent infrastructure-sector modelling.
For the unification of the existing infrastructure-sector models, we propose the implementation of a generic communication
interface, which allows the separate sector-models to communicate at the necessarily disaggregate level in order to account
for interdependencies appropriately. This approach allows for infrastructure provision modelling under one unified umbrella
in a minimally invasive way, while conserving crucial individualities of the separate models. This is achieved through a generic
network description, in which we solve the resource allocation through a pragmatic network-flow algorithm that resembles
market and consumer behaviour. The developed framework establishes the basis for fully integrated infrastructure evaluation
and hence cross-sectorial infrastructure investment decision making — a crucial tool in times of tight governmental budgets
MAMA: An Algebraic Map for the Secular Dynamics of Planetesimals in Tight Binary Systems
We present an algebraic map (MAMA) for the dynamical and collisional
evolution of a planetesimal swarm orbiting the main star of a tight binary
system (TBS). The orbital evolution of each planetesimal is dictated by the
secular perturbations of the secondary star and gas drag due to interactions
with a protoplanetary disk. The gas disk is assumed eccentric with a constant
precession rate. Gravitational interactions between the planetesimals are
ignored. All bodies are assumed coplanar. A comparison with full N-body
simulations shows that the map is of the order of 100 times faster, while
preserving all the main characteristics of the full system.
In a second part of the work, we apply MAMA to the \gamma-Cephei, searching
for friendly scenarios that may explain the formation of the giant planet
detected in this system. For low-mass protoplanetary disks, we find that a
low-eccentricity static disk aligned with the binary yields impact velocities
between planetesimals below the disruption threshold. All other scenarios
appear hostile to planetary formation
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