Nerve complexes of circular arcs

We show that the nerve complex of n arcs in the circle is homotopy equivalent to either a point, an odd-dimensional sphere, or a wedge sum of spheres of the same even dimension. Moreover this homotopy type can be computed in time O(n log n). For the particular case of the nerve complex of evenly-spaced arcs of the same length, we determine the dihedral group action on homology, and we relate the complex to a cyclic polytope with n vertices. We give three applications of our knowledge of the homotopy types of nerve complexes of circular arcs. First, we use the connection to cyclic polytopes to give a novel topological proof of a known upper bound on the distance between successive roots of a homogeneous trigonometric polynomial. Second, we show that the Lovasz bound on the chromatic number of a circular complete graph is either sharp or off by one. Third, we show that the Vietoris--Rips simplicial complex of n points in the circle is homotopy equivalent to either a point, an odd-dimensional sphere, or a wedge sum of spheres of the same even dimension, and furthermore this homotopy type can be computed in time O(n log n)

Alcohol consumption in young adults: the role of multisensory imagery.

Accepted 19.11.2013Little is known about the subjective experience of alcohol desire and craving in young people. Descriptions of alcohol urges continue to be extensively used in the everyday lexicon of young, non-dependent drinkers. Elaborated Intrusion (EI) Theory contends that imagery is central to craving and desires, and predicts that alcohol-related imagery will be associated with greater frequency and amount of drinking. This study involved 1,535 age stratified 18- 25 year olds who completed an alcohol–related survey that included the Imagery scale of the Alcohol Craving Experience (ACE) questionnaire. Imagery items predicted 12-16% of the variance in concurrent alcohol consumption. Higher total Imagery subscale scores were linearly associated with greater drinking frequency and lower self-efficacy for moderate drinking. Interference with alcohol imagery may have promise as a preventive or early intervention target in young people

Social marketing's consumer myopia: Applying a behavioural ecological model to address wicked problems

Purpose – Addressing calls for broadening social marketing thinking beyond “individualistic” parameters, this paper aims to describe a behavioural ecological systems (BEM) approach to enhance understanding of social markets. Design/methodology/approach – A conceptual framework – the BEM – is presented and discussed within a context of alcohol social change. Findings – The BEM emphasises the relational nature of behaviour change, where individuals are embedded in an ecological system that involves the performances of behaviour and social change within historical, social, cultural, physical and environmental settings. Layers of influence on actors are characterised as macro (distant, large in scale), exo (external, remote from individuals), meso (between the individual and environments) and micro (the individual within their social setting). The BEM can be applied to guide social marketers towards creating solutions that focus on collaboration amongst market actors rather than among consumers. Practical implications – The BEM contributes to a broader holistic view of social ecologies and behaviour change; emphasises the need for social marketers to embrace systems thinking; and recognises that relationships between actors at multiple layers in social change markets are interactive, collaborative and embedded in dynamic social contexts. Importantly, a behavioural ecological systems approach enables social marketers to develop coherent, integrated and multi-dimensional social change programmes. Originality/value – The underlying premise of the BEM brings forward relational logic as the foundation for future social marketing theory and practice. Taking this approach to social market change focuses strategy on the intangible aspects of social offerings, inclusive of the interactions and processes of value creation (and/or destruction) within a social marketing system to facilitate collaboration and interaction across a network of actors so as to overcome barriers and identify solutions to social problems

The Australian Space Eye: studying the history of galaxy formation with a CubeSat

The Australian Space Eye is a proposed astronomical telescope based on a 6U CubeSat platform. The Space Eye will exploit the low level of systematic errors achievable with a small space based telescope to enable high accuracy measurements of the optical extragalactic background light and low surface brightness emission around nearby galaxies. This project is also a demonstrator for several technologies with general applicability to astronomical observations from nanosatellites. Space Eye is based around a 90 mm aperture clear aperture all refractive telescope for broadband wide field imaging in the i and z bands.Comment: 19 pages, 14 figures, submitted for publication as Proc. SPIE 9904, 9904-56 (SPIE Astronomical Telescopes & Instrumentation 2016

D-neighborhood complex of a graph, The

2014 Summer.The Neighborhood complex of a graph, G, is an abstract simplicial complex formed by the subsets of the neighborhoods of all vertices in G. The construction of this simplicial complex can be generalized to use any subset of graph distances as a means to form the simplices in the associated simplicial complex. Consider a simple graph G with diameter d. Let D be a subset of {0,1,..., d}. For each vertex, u, the D-neighborhood is the simplex consisting of all vertices whose graph distance from u lies in D. The D-neighborhood complex of G, denoted DN(G,D), is the simplicial complex generated by the D-neighborhoods of vertices in G. We relate properties of the graph G with the homology of the chain complex associated to DN(G,D)

Domain-based perceptions of risk:a case study of lay and technical community attitudes towards managed aquifer recharge

Despite growing water scarcity, communities in many parts of the developed world often reject technically and economically sound options for water augmentation. This paper reports findings from a study investigating risk perceptions associated with a proposed Managed Aquifer Recharge scheme in Australia. Q-Methodology was used to compare decision-making frameworks of lay community and „technical expert‟ participants. Technical expert participants were also asked to approximate the decision-making framework of a „typical‟ community member. The emerging contrasts between lay community frameworks and those approximated by technical experts suggest that there are prevailing yet errant assumptions about lay community attitudes towards new technologies. The findings challenge the characterisation of the lay community and technical experts as being in entrenched opposition with one another