35,150 research outputs found
Contractive Spaces and Relatively Contractive Maps
We present an exposition of contractive spaces and of relatively contractive
maps. Contractive spaces are the natural opposite of measure-preserving actions
and relatively contractive maps the natural opposite of relatively
measure-preserving maps. These concepts play a central role in the work of the
author and J.~Peterson on the rigidity of actions of semisimple groups and
their lattices and have also appeared in recent work of various other authors.
We present detailed definitions and explore the relationship of these phenomena
with other aspects of the ergodic theory of group actions, proving along the
way several new results, with an eye towards explaining how contractiveness is
intimately connected with rigidity phenomena.Comment: arXiv admin note: substantial text overlap with arXiv:1303.394
A New ERA? Marketing and Delivering a User-Education Event for Academic Staff
Covers project management and innovations introduced in an Information Literacy event for academic staff at Birmingham City University (formerly UCE Birmingham)
Modeling and Control of the Automated Radiator Inspection Device
Many of the operations performed at the Kennedy Space Center (KSC) are dangerous and repetitive tasks which make them ideal candidates for robotic applications. For one specific application, KSC is currently in the process of designing and constructing a robot called the Automated Radiator Inspection Device (ARID), to inspect the radiator panels on the orbiter. The following aspects of the ARID project are discussed: modeling of the ARID; design of control algorithms; and nonlinear based simulation of the ARID. Recommendations to assist KSC personnel in the successful completion of the ARID project are given
RAS and STM investigations of pentacene molecules on metal and semiconductor surfaces
In this study the electronic surface states and surface reconstructions of an organic molecule on semiconductor and metal surfaces were investigated with Reflectance Anisotropy Spectroscopy (RAS), Scanning Tunnelling Microscopy (STM) and photoemission techniques.
The design, construction and operation of a Reflectance Anisotropy Spectrometer are described in detail. The RAS technique was applied to the investigation o f pentacene on the Au(110)-(2xl) surface. It was found that the pentacene molecules adsorbed on this surface shows three observable electronic transitions in the 1.6 eV-5 eV photon energy range. At monolayer coverage there are distinct changes in the RAS spectrum that can be associated with a change in the orientation of the molecule on the gold surface.
STM was applied to the investigation o f pentacene adsorbed on the Au(llO)- (2x1) and the A g /S i(lll)-(7 x 7 ) surface. It was found that on the Au(l 10)-(2xl) surface, below a monolayer the pentacene molecule adsorbs parallel to and between the Au rows in the [11 0] direction, While above a monolayer the molecule changes direction and preferentially adsorbs across the gold rows. This change in orientation accounts for the changes in the RAS spectra above a monolayer. The effect o f annealing on the molecular ordering was also studied. These interfaces were also studied by core level and valence band photoemission using a synchrotron light source. Deposition o f pentacene on the Ag/Si(l 11)-(V3 xy/3 ) surface produced three distinct ordered structures for coverages up to one monolayer. It is concluded from the RAS, STM, synchrotron studies that the molecule lies flat on the Au(110) and Ag/Si(l 11) surfaces
On-shell Recursion Relations for n-point QCD
We present on the use of on-shell recursion relations. These can be used not
only for calculating tree amplitudes, including those with masses, but also to
compute analytically the missing rational terms of one-loop QCD amplitudes.
Combined with the cut-containing pieces calculated using a unitarity approach
complete one-loop QCD amplitudes can be derived. This approach is discussed in
the context of the adjacent 2-minus all-multiplicity QCD gluon amplitude.Comment: Talk presented at the 7th Workshop On Continuous Advances In QCD,
11-14 May 2006, Minneapolis, Minnesot
Conforming restricted Delaunay mesh generation for piecewise smooth complexes
A Frontal-Delaunay refinement algorithm for mesh generation in piecewise
smooth domains is described. Built using a restricted Delaunay framework, this
new algorithm combines a number of novel features, including: (i) an
unweighted, conforming restricted Delaunay representation for domains specified
as a (non-manifold) collection of piecewise smooth surface patches and curve
segments, (ii) a protection strategy for domains containing curve segments that
subtend sharply acute angles, and (iii) a new class of off-centre refinement
rules designed to achieve high-quality point-placement along embedded curve
features. Experimental comparisons show that the new Frontal-Delaunay algorithm
outperforms a classical (statically weighted) restricted Delaunay-refinement
technique for a number of three-dimensional benchmark problems.Comment: To appear at the 25th International Meshing Roundtabl
<i>Every House on Langland Road</i> – the production of archival, architectural and artistic spaces
This article describes an Arts Council England project, undertaken by the author and a photographer, to examine spatial and temporal relations between an art project, its subject and its audience. The project explored and documented the architecture of a modernist 1970s housing estate, Netherfield, designed by a group of four architects for the new city of Milton Keynes. The estate has not aged well and the visual remnants of what had been an ambitious and idiosyncratic housing scheme were to be photographed and juxtaposed with the original architectural drawings. The photographic process contributed to a more complex series of perspectives which included the archival history of the estate and its surrounding new city, the people who live there and my own reflections on a council estate childhood. In turn, these perspectives are set out in this article in terms of the spatial and temporal realms in which they are, and continue to be, produced. Loosely conceived in terms of Lefebvre’s production of space triad, these realms are traced through the estate’s historical narrative from plans to buildings which then converge in the eventual art work. The gallery is seen as an assemblage of multiple connections drawn between various productions of archival, architectural and artistic spaces
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