African University of Science and Technology: Recent submissions
Now showing items 1841-1860 of 4824
-
A Quantum Paradox of Choice: More Freedom Makes Summoning a Quantum State Harder
(American Physical SocietyPhysical Review A, 2016)The properties of quantum information in space-time can be investigated by studying operational tasks, such as ‘summoning’, in which an unknown quantum state is supplied at one point, and a call is made at another for it ...
-
Turbulent mixing, restratification, and phytoplankton growth at a submesoscale eddy
(WileyGeophysical Research Letters, 2016-05-13)High-resolution large-eddy simulations are used to study the influence of submesoscale mixed layer instability and small-scale turbulence on phytoplankton growth in light-limited conditions. Four simulations are considered ...
-
Bilevel Parameter Learning for Higher-Order Total Variation Regularisation Models
(SpringerJournal of Mathematical Imaging and Vision, 2016-06-01)We consider a bilevel optimisation approach for parameter learning in higher-order total variation image reconstruction models. Apart from the least squares cost functional, naturally used in bilevel learning, we propose ...
-
Dimensional reduction in numerical relativity: Modified cartoon formalism and regularization
(World Scientific Publishing CompanyInternational Journal of Modern Physics D, 2016-06-01)We present in detail the Einstein equations in the Baumgarte–Shapiro–Shibata–Nakamura formulation for the case of D-dimensional spacetimes with SO(D−d)isometry based on a method originally introduced in Ref. 1. Regularized ...
-
Numerical simulations of stellar collapse in scalar-tensor theories of gravity
(Institute of PhysicsClassical and Quantum Gravity, 2016-05-31)We present numerical-relativity simulations of spherically symmetric core collapse and compact-object formation in scalar-tensor theories of gravity. The additional scalar degree of freedom introduces a propagating monopole ...
-
Numerical simulations of stellar collapse in scalar-tensor theories of gravity
(Institute of PhysicsClassical and Quantum Gravity, 2016-05-31)We present numerical-relativity simulations of spherically symmetric core collapse and compact-object formation in scalar-tensor theories of gravity. The additional scalar degree of freedom introduces a propagating monopole ...
-
A short proof that every finite graph has a tree-decomposition displaying its tangles
(ElsevierEuropean Journal of Combinatorics, 2016-06-08)We give a short proof that every finite graph (or matroid) has a tree-decomposition that displays all maximal tangles. This theorem for graphs is a central result of the graph minors project of Robertson and Seymour and ...
-
Localization and broadband follow-up of the gravitational-wave transient GW150914
(IOP PublishingAstrophysical Journal Letters, 2016-07-20)A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and ...
-
Micro-Tug-of-War: A Selective Control Mechanism for Magnetic Swimmers
(American Physical SocietyPhysical Review Applied, 2016-06-30)One of the aspirations for artificial microswimmers is their application in noninvasive medicine. For any practical use, adequate mechanisms enabling control of multiple artificial swimmers will be of paramount importance. ...
-
Squirmers with swirl - a model for Volvox swimming
(Cambridge University PressJournal of Fluid Mechanics, 2016)Colonies of the green alga Volvox are spheres that swim through the beating of pairs of flagella on their surface somatic cells. The somatic cells themselves are mounted rigidly in a polymeric extracellular matrix, fixing ...
-
Bridging the digital divide in African post-conflict countries: a case study of the DRC cities in Kinshasa and Kananga
(University of Cape TownFaculty of ScienceDepartment of Computer Science, 2007)The digital divide is largely seen as the main problem that developing economies and societies must overcome to gain economic productivity and social welfare. In this document we state that modern western perception of the ...
-
A comparison of computational methods for detecting bursts in neuronal spike trains and their application to human stem cell-derived neuronal networks
(American Physiological SocietyJournal of Neurophysiology, 2016-04-20)Accurate identification of bursting activity is an essential element in the characterization of neuronal network activity. Despite this, no one technique for identifying bursts in spike trains has been widely adopted. ...
-
An a$_{0}$ resonance in strongly coupled πη, K$\bar K$ scattering from lattice QCD
(American Physical SocietyPhysical Review D, 2016-05-11)We present the first calculation of coupled-channel meson-meson scattering in the isospin =1, G-parity negative sector, with channels πη, K$\bar K$ and πη′, in a first-principles approach to QCD. From the discrete spectrum ...
-
Spontaneous Wave Generation at Strongly Strained Density Fronts
(American Meteorological SocietyJournal of Physical Oceanography, 2016-06-23)A simple analytical model is presented describing the spontaneous generation of inertia–gravity waves at density fronts subjected to strong horizontal strain rates. The model considers fronts of arbitrary horizontal and ...
-
Evanescent ergosurfaces and ambipolar hyperkähler metrics
(SpringerJournal of High Energy Physics, 2016-04-20)A supersymmetric solution of 5d supergravity may admit an ‘evanescent ergosurface’: a timelike hypersurface such that the canonical Killing vector field is timelike everywhere except on this hypersurface. The hyperkähler ...
-
Efficient advert assignment
(InformsOperations Research, 2016-07-01)We develop a framework for the analysis of large-scale ad auctions where adverts are assigned over a continuum of search types. For this pay-per-click market, we provide an efficient mechanism that maximizes social welfare. ...
-
Stackings and the W-cycles conjecture
We prove Wise’s W-cycles conjecture: Consider a compact graph Γ′ immersing into another graph Γ. For any immersed cycle Λ : S¹ → Γ, we consider the map Λ′ from the circular components S of the pullback to Γ′. Unless Λ′ is ...
-
A Heuristic Image Search Algorithm for Active Shape Model Segmentation of the Caudate Nucleus and Hippocampus in Brain MR Images of Children with FASD
(South African Institute of Computer Scientists and Information TechnologistsUniversity of Cape Town, 2012)Magnetic Resonance Imaging provides a non-invasive means to study the neural correlates of Fetal Alcohol Spectrum Disorder (FASD) - the most common form of preventable mental retardation worldwide. One approach aims to ...
-
Evolution of initially contracting Bianchi Class A models in the presence of an ultra-stiff anisotropic pressure fluid
(Institute of PhysicsClassical and Quantum Gravity, 2016-05-12)We study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether ...
-
A WKB approximation of elastic waves travelling on a shell of revolution
(ElsevierJournal of Sound and Vibration, 2016-08-04)This paper is concerned with the elastic waveguide properties of an infinite pipe with circular cross section whose radius varies slowly along its length. The equations governing the elastodynamics of such shells are derived ...
