Flat rank of automorphism groups of buildings

The flat rank of a totally disconnected locally compact group G, denoted flat-rk(G), is an invariant of the topological group structure of G. It is defined thanks to a natural distance on the space of compact open subgroups of G. For a topological Kac-Moody group G with Weyl group W, we derive the inequalities: alg-rk(W)\le flat-rk(G)\le rk(|W|\_0). Here, alg-rk(W) is the maximal $\mathbb{Z}$-rank of abelian subgroups of W, and rk(|W|\_0) is the maximal dimension of isometrically embedded flats in the CAT0-realization |W|\_0. We can prove these inequalities under weaker assumptions. We also show that for any integer n \geq 1 there is a topologically simple, compactly generated, locally compact, totally disconnected group G, with flat-rk(G)=n and which is not linear

Scale-multiplicative semigroups and geometry: automorphism groups of trees

A scale-multiplicative semigroup in a totally disconnected, locally compact group $G$ is one for which the restriction of the scale function on $G$ is multiplicative. The maximal scale-multiplicative semigroups in groups acting 2-transitively on the set of ends of trees without leaves are determined in this paper and shown to correspond to geometric features of the tree.Comment: submitted to Groups, Geometry, and Dynamic

Non-monotonic fluctuation spectra of membranes pinned or tethered discretely to a substrate

The thermal fluctuation spectrum of a fluid membrane coupled harmonically to a solid support by an array of tethers is calculated. For strong tethers, this spectrum exhibits non-monotonic, anisotropic behavior with a relative maximum at a wavelength about twice the tether distance. The root mean square displacement is evaluated to estimate typical membrane displacements. Possible applications cover pillar-supported or polymer-tethered membranes.Comment: 4 pages, 5 figure

Contraction groups and scales of automorphisms of totally disconnected locally compact groups

We study contraction groups for automorphisms of totally disconnected locally compcat groups using the scale of the automorphism as a tool. The contraction group is shown to be unbounded when the inverse automorphism has non-trivial scale and this scale is shown to be the inverse value of the modular function on the closure of the contraction group at the automorphism. The closure of the contraction group is represented as acting on a homogenous tree and closed contraction groups are characterised.Comment: revised version, 29 pages, to appear in Israel Journal of Mathematics, please note that document starts on page

Inequality and Envy

Using a simple axiomatic structure we characterise two classes ofinequality indices - absolute and relative - that take into account "envy"in the income distribution. The concept of envy incorporated hereconcerns the distance of each person's income from his or herimmediately richer neighbour. This is shown to be similar to justiceconcepts based on income relativities.Inequality, envy, transfer principle.

Complaints and Inequality

Temkin (1986,1993) sets out a philosophical basis for the analysis of income inequality that provides an important alternative to the mainstream welfarist approach. We show that the Temkin principles can be characterised by a parsimonious axiomatic structure and we use this structure to derive a new class of inequality indices and an inequality ordering. This class of indices has a family relationship to well-known measures of inequality, deprivation and poverty. The ordering is shown to have properties analogous to second-order dominance results.Inquality, complaints, transfer principle.

Fluid Machine - Bearing Inserts

The present disclosure relates to fluid machines, especially compressors, more especially screw compressors. More particularly the present disclosure describes a fluid machine comprising at least one rotor, the rotor including a rotor drive shaft extending from the rotor, a housing in which is mounted the rotor, and at least one bearing insert which mounts around the rotor drive shaft at a first end of the rotor and which includes at least one bearing within it and attaches to the housing. The present disclosure also describes bearing inserts suitable for use on such fluid machines

Dynamics of quantum adiabatic evolution algorithm for Number Partitioning

We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size $n$. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxilary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum excitation gap, $g_{\rm min}={\cal O}(n 2^{-n/2})$, corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simulteneous fipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimenssional quantum diffusion in the energy space. This effect provides a general limitation on the power of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.Comment: 32 pages, 5 figures, 3 Appendices; List of additions compare to v.3: (i) numerical solution of the stationary Schroedinger equation for the adiabatic eigenstates and eigenvalues; (ii) connection between the scaling law of the minimum gap with the problem size and the shape of the coarse-grained distribution of the adiabatic eigenvalues at the avoided-crossing poin

Modelling, Analysis and Design of a Bottle-Shaped Building

The emergence of unique structures around the world have turned the points of it location to centers of attraction thereby yielding benefits to the economy of the cities where they are cited. Worldwide, iconic structures stand out, placing its location on the map. Hence, the idea of bottle-shaped building was birthed trying to put bottle to tension. This research models, analyses and designs a bottle-shaped structure according the British Standard. The works carried out in this research consisted of step by step generation of a three dimensional computer models of the bottle shaped super- structure, analysis and design of critical members for various combination of dead load, live load and the wind load and the critical analysis of the results obtained. The results of the nonlinear finite element analysis carried out for different ranges of loading scenarios were so exiting. It confirmed the validity of the approach adopted for the model and showed that the realization of the structure is very feasible