Subgroup Distortion in Wreath Products of Cyclic Groups

We study the effects of subgroup distortion in the wreath products A wr Z, where A is finitely generated abelian. We show that every finitely generated subgroup of A wr Z has distortion function equivalent to some polynomial. Moreover, for A infinite, and for any polynomial l^k, there is a 2-generated subgroup of A wr Z having distortion function equivalent to the given polynomial. Also a formula for the length of elements in arbitrary wreath product H wr G easily shows that the group Z_2 wr Z^2 has distorted subgroups, while the lamplighter group Z_2 wr Z has no distorted (finitely generated) subgroups

On asymptotic dimension of groups

We prove a version of the countable union theorem for asymptotic dimension and we apply it to groups acting on asymptotically finite dimensional metric spaces. As a consequence we obtain the following finite dimensionality theorems. A) An amalgamated product of asymptotically finite dimensional groups has finite asymptotic dimension: asdim A *_C B < infinity. B) Suppose that G' is an HNN extension of a group G with asdim G < infinity. Then asdim G'< infinity. C) Suppose that \Gamma is Davis' group constructed from a group \pi with asdim\pi < infinity. Then asdim\Gamma < infinity.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol1/agt-1-4.abs.htm

Universal Realisators for Homology Classes

We study oriented closed manifolds M^n possessing the following Universal Realisation of Cycles (URC) Property: For each topological space X and each integral homology class z of it, there exist a finite-sheeted covering \hM^n of M^n and a continuous mapping f of \hM^n to X such that f takes the fundamental class [\hM^n] to kz for a non-zero integer k. We find wide class of examples of such manifolds M^n among so-called small covers of simple polytopes. In particular, we find 4-dimensional hyperbolic manifolds possessing the URC property. As a consequence, we prove that for each 4-dimensional oriented closed manifold N^4, there exists a mapping of non-zero degree of a hyperbolic manifold M^4 to N^4. This was conjectured by Kotschick and Loeh.Comment: 20 pages, 1 figure; in version 2 minor corrections are made, 4 bibliography items and 1 figure are adde

The curious case of large-N expansions on a (pseudo)sphere

We elucidate the large-N dynamics of one-dimensional sigma models with spherical and hyperbolic target spaces and find a duality between the Lagrange multiplier and the angular momentum. In the hyperbolic model we propose a new class of operators based on the irreducible representations of hyperbolic space. We also uncover unexpected zero modes which lead to the double scaling of the 1/N expansion and explore these modes using Gelfand-Dikiy equations.Comment: 18 pages, 3 figure

PyCBC Live: Rapid Detection of Gravitational Waves from Compact Binary Mergers

We introduce an efficient and straightforward technique for rapidly detecting gravitational waves from compact binary mergers. We show that this method achieves the low latencies required to alert electromagnetic partners of candidate binary mergers, aids in data monitoring, and makes use of multidetector networks for sky localization. This approach was instrumental to the analysis of gravitational-wave candidates during the second observing run of Advanced LIGO, including the period of coincident operation with Advanced Virgo, and in particular the analysis of the first observed binary neutron star merger GW170817, where it led to the first tightly localized sky map ($31~\mathrm{deg}^2$) used to identify AT 2017gfo. Operation of this analysis also enabled the initial discovery of GW170104 and GW170608 despite non-nominal observing of the instrument.Comment: 10 pages, 5 figures, submitted to Physical Review

Rethinking Australia’s International Past: Identity, Foreign Policy and India in the Australian Colonial Imagination

This article examines the ways in which Australia’s global connections during the colonial period have shaped its contemporary international political identity and the implications of such an approach for the study of Australian foreign policy and international relations (IR). This is particularly pertinent due to recent historiographical reconceptualization of nineteenth century colonial networks, which suggest Australia’s connections to India are far more important than previously considered. These issues are explored through a case study of Australia’s links with India prior to Federation, employing a discursive analysis of public debate on utilizing Indian indentured laborers in tropical Northern Australia

Coming home again : Johannes Hofer, Edmund Spenser, and premodern nostalgia

The word ‘nostalgia’ was coined by the Swiss medical student Johannes Hofer in his 1688 Dissertatio medica de nostalgia, oder Heimwehe. Hofer’s treatise and Edmund Spenser’s 1595 poem Colin Clouts Come Home Againe exemplify a premodern nostalgia. Hofer moves between moments of familiarity and alienation, while Spenser’s poem offers a richly imaginative response to the Elizabethan attempt to ‘plant’ new homes in Ireland. In each case, premodern nostalgia situates the longing for home within patterns of doubling and repetition that unsettle ideas of origin and belonging even as they propagate them.PostprintPeer reviewe