Detecting highly overlapping community structure by greedy clique expansion

In complex networks it is common for each node to belong to several communities, implying a highly overlapping community structure. Recent advances in benchmarking indicate that existing community assignment algorithms that are capable of detecting overlapping communities perform well only when the extent of community overlap is kept to modest levels. To overcome this limitation, we introduce a new community assignment algorithm called Greedy Clique Expansion (GCE). The algorithm identifies distinct cliques as seeds and expands these seeds by greedily optimizing a local fitness function. We perform extensive benchmarks on synthetic data to demonstrate that GCE's good performance is robust across diverse graph topologies. Significantly, GCE is the only algorithm to perform well on these synthetic graphs, in which every node belongs to multiple communities. Furthermore, when put to the task of identifying functional modules in protein interaction data, and college dorm assignments in Facebook friendship data, we find that GCE performs competitively.Comment: 10 pages, 7 Figures. Implementation source and binaries available at http://sites.google.com/site/greedycliqueexpansion

The Effect of NAG–thiazoline on Morphology and Surface Hydrophobicity of Escherichia Coli

The β-hexosaminidase inhibitor and structural analog of the putative oxazolium reaction intermediate of lytic transglycosylases, N-acetylglucosamine thiazoline (NAG–thiazoline), was synthesized in 46% overall yield and tested as an inhibitor of Escherichia coli growth. NAG–thiazoline, at concentrations up to 1 mg/ml, was not found to affect the viability of E. coli DH5α

Metaheuristics For Solving Real World Employee Rostering and Shift Scheduling Problems

Optimising resources and making considerate decisions are central concerns in any responsible organisation aiming to succeed in efficiently achieving their goals. Careful use of resources can have positive outcomes in the form of fiscal savings, improved service levels, better quality products, improved awareness of diminishing returns and general output efficiency, regardless of field. Operational research techniques are advanced analytical tools used to improve managerial decision-making. There have been a variety of case studies where operational research techniques have been successfully applied to save millions of pounds. Operational research techniques have been successfully applied to a multitude of fields, including agriculture, policing, defence, conservation, air traffic control, and many more. In particular, management of resources in the form of employees is a challenging problem --- but one with the potential for huge improvements in efficiency. The problem this thesis tackles can be divided into two sub-problems; the personalised shift scheduling & employee rostering problem, and the roster pattern problem. The personalised shift scheduling & employee rostering problem involves the direct scheduling of employees to hours and days of week. This allows the creation of schedules which are tailored to individuals and allows a fine level over control over the results, but with at the cost of a large and challenging search space. The roster pattern problem instead takes existing patterns employees currently work, and uses these as a pool of potential schedules to be used. This reduces the search space but minimises the number of changes to existing employee schedules, which is preferable for personnel satisfaction. Existing research has shown that a variety of algorithms suit different problems and hybrid methods are found to typically outperform standalone ones in real-world contexts. Several algorithmic approaches for solving variations of the employee scheduling problem are considered in this thesis. Initially a VNS approach was used with a Metropolis-Hastings acceptance criterion. The second approach utilises ER&SR controlled by the EMCAC, which has only been used in the field of exam timetabling, and has not before been used within the domain of employee scheduling and rostering. ER&SR was then hybridised with our initial approach, producing ER&SR with VNS. Finally, ER&SR was hybridised into a matheuristic with Integer Programming and compared to the hybrid's individual components. A contribution of this thesis is evidence that the algorithm ER&SR has merit outside of the original sub-field of exam scheduling, and can be applied to shift scheduling and employee rostering. Further, ER&SR was hybridised and schedules produced by the hybridisations were found to be of higher quality than the standalone algorithm. In the literature review it was found that hybrid algorithms have become more popular in real-world problems in recent years, and this body of work has explored and continued this trend. Problem formulations in this thesis provide insight into creating constraints which satisfy the need for minimising employee dissatisfaction, particularly in regards to abrupt change. The research presented in this thesis has positively impacted a multinational and multibillion dollar field service operations company. This has been achieved by implementing a variety of techniques, including metaheuristics and a matheuristic, to schedule shifts and roster employees over a period of several months. This thesis showcases the research outputs by this project, and highlights the real-world impact of this research

Accessing and Decoding Communities of Cultural Capital

Ours is a discussion paper which addresses, chiefly, the conference themes of: ‘equity & social justice’ and ‘theory & methods’. The paper is based on long-standing professional expertise in the area of Widening Participation (WP) in Art, Design and Architecture (ADA) in Higher Education and on research interest in the traditions and conventions, both bureaucratic and linguistic, which serve the infrastructure of formal education in ADA. The first part of the paper argues for a strategic approach to WP agendas within ADA to be informed by 1) the theory and methods of Pierre Bourdieu (1930-2002), specifically his work on the ‘aristocracy of culture’ and the operations of ‘cultural capital’ and 2) the recent work of James Elkins (b.1955) on the conventions of contemporary art education, in particular his application of Stanley Fish’s concept of ‘interpretive communities’ to ADA. The emergent strategy is one which recognises that socio-economic class remains the predominant obstacle to achieving credible diversity of student background in creative education at HE level. As Bourdieu makes clear, the non-acquisition of the codes and behaviours of operative cultural capital creates an acute and erroneous sense of incompleteness on the part of a reflexive working class applicant to art school who inwardly registers his/her perceived difference in capital inheritance. Elkins is right, we argue, to draw our attention to the explicit and implicit sharing of bureaucratic and evaluative vocabularies within the art academy: he usefully demonstrates the ways in which such vocabularies reinforce a complacent sense of liberal tolerance while cementing interpretive positions in ADA familiar to those with an appropriate level of cultural and educational wherewithal. For the second part of our presentation we will introduce to delegates GSA’s Prato Project: an international exchange programme between GSA and Monash University. This unique project sees Scottish students from lower socio-economic backgrounds join Australian liberal arts students in Tuscany. An intensive project, it has a twofold impact – on both ‘non-acquisition’ and ‘decoding vocabularies’, following Bourdieu and Elkins – by helping to familiarise less culturally privileged students with world renowned examples of renaissance culture, and by offering them a discursive environment in which to share and decode cultural preconceptions, build confidence, and help them identify as genuine participants in local, national and international culture. Often lacking confidence in, and alienated from, the dominant culture that pervades UK art schools, the following quote is a typical example of the project’s impact: ‘I thought I was prepared for what was going to happen on the trip. I don’t think I knew exactly how much it would have contributed to the person I am today. It changed many things about me such as my confidence, independence and my hunger for learning. Since the trip I have been to Prague, Berlin, Barcelona and Riga. This is all because I now have the confidence to travel’. In sum, our paper recommends that socio-economic class, and the ‘coding’ confidence issues which ensue, be kept in the foreground when addressing equity of participation in HE ADA. For open discussion we wish to hear of colleagues’ efforts in these areas, and share good practice, with the Prato Project as touchstone, to further test the insight and potential for institutional change which these theories and methods present

INCOME TAX ASPECTS OF LIQUIDATION IN MULTIPERIOD LINEAR GROWTH MODELS

Public Economics,

Creativity, Community, and Growth: A Social Geography of Urban Craft Beer

To better understand the non-economic drivers of growth in emerging industries, this paper examines the craft beer industry. Specifically, the paper will review two examples - the Black Cloister Brewing Company in Toledo, OH and 3rd Turn Brewery, Louisville, KY - to understand how the values of entrepreneurs and local firms that are situated at the nexus of work, place, and creativity promote growth. Further, the paper will consider the socio-cultural meaning of creativity relative to the craft beer industry and the many ways in which the concept of innovation traditionally used by economic geographers to understand growth can be better understood within the context of creativity in some industries. In doing so, the paper represents a conceptual shift away from innovation towards creativity, as well as community

Effect of Facial Encumbrance on Excimer Formation and Charge Resonance Stabilization in Model Bichromophoric Assemblies

Excimer formation and charge resonance stabilization in covalently linked bichromophoric systems with flexible spacers are important processes relevant to biochemistry and functional materials. Requiring a π-stacked cofacial arrangement of a pair of aromatic molecules at a van der Waals contact, the underlying geometrical reorganization that accompanies these events continues to be debated. Here we use a variety of methods including two-color resonant two-photon ionization spectroscopy (2CR2PI), ion yield measurements, hole-burning spectroscopy (HB), and laser-induced fluorescence (LIF) excitation and emission spectroscopy to compare the gas-phase spectroscopy and dynamics of the van der Waals dimers of fluorene, 9-methylfluorene (MF), and 9,9′-dimethylfluorene (F1). The goal of this work is to probe the influence of methyl substitution on the dynamics of excimer formation and charge resonance (CR) stabilization. The fluorene dimer, (F)2, displays lifetime broadened electronic spectra and the dominance of excimer emission, consistent with a rapid (picoseconds) formation of a π-stacked excimer upon electronic excitation. Ion yield measurements of (F)2 reveal a lowering of the ionization potential (IP) by some 0.38 eV relative to the monomer, reflecting significant CR stabilization. These trends are mirrored in the 9-methylfluorene dimer, (MF)2, as one face of the π-system remains open. In contrast, the electronic spectrum of the dimethyl-substituted dimer, (F1)2, shows narrow features representing a single band system, and analysis of the torsional structure in dispersed fluorescence spectra identifies this as emission from the locally excited state of a tilted (non-π-stacked) dimer, with no evidence of excimeric emission. The structure of this dimer reflects the increased importance of C–H/π interactions in the dimethyl-substituted system, as increased steric constraints block a cofacial approach. The IP of (F1)2 shows CR stabilization which is roughly 1/2 of that in π-stacked (F)2 dimer. Extensive theoretical calculations support these findings and show the importance of sandwich-type configurations for excitonic delocalization and CR stabilization

First Experimental Evidence for the Diverse Requirements of Excimer vs Hole Stabilization in π-Stacked Assemblies

Exciton formation and charge separation and transport are key dynamical events in a variety of functional polymeric materials and biological systems, including DNA. Beyond the necessary cofacial approach of a pair of aromatic molecules at van der Waals contact, the extent of overlap and necessary geometrical reorganization for optimal stabilization of an excimer vs dimer cation radical remain unresolved. Here, we compare experimentally the dynamics of excimer formation (via emission) and charge stabilization (via threshold ionization) of a novel covalently linked, cofacially stacked fluorene dimer (F2) with the unlinked van der Waals dimer of fluorene, that is, (F)2. Although the measured ionization potentials are identical, the excimeric state is stabilized by up to ∼30 kJ/mol in covalently linked F2. Supported by theory, this work demonstrates for the first time experimentally that optimal stabilization of an excimer requires a perfect sandwich-like geometry with maximal overlap, whereas hole stabilization in π-stacked aggregates is less geometrically restrictive