Identity and Search in Social Networks

Social networks have the surprising property of being "searchable": Ordinary people are capable of directing messages through their network of acquaintances to reach a specific but distant target person in only a few steps. We present a model that offers an explanation of social network searchability in terms of recognizable personal identities: sets of characteristics measured along a number of social dimensions. Our model defines a class of searchable networks and a method for searching them that may be applicable to many network search problems, including the location of data files in peer-to-peer networks, pages on the World Wide Web, and information in distributed databases.Comment: 4 page, 3 figures, revte

Synthesis and characterisation of branched polymers

HyperMacs and HyperBlocks are polymers with highly branched architectures. The building blocks for these materials, AB(_2) macromonomers, are synthesized by living anionic polymerization and are well-defined in terms of molecular weight and polydispersity. The nature of the coupling reaction used to generate the highly branched HyperMacs results in branched polymers with a distribution of molecular weights and architectures. Previously a strategy for the synthesis of polystyrene HyperMacs has been reported in which the extent of reaction was limited by an unknown factor. In this thesis the modifications made to the synthetic strategy are reported for the production of more highly branched polystyrene HyperMacs or 'super' HyperMacs. Other variations along this theme include the addition of a B3 core creating core HyperMacs. Modifications to the improved HyperMac synthesis enabled the construction of polybutadiene AB(_2) macromonomers, resulting in polybutadiene HyperMacs; as well as triblock copolymer AB(_2) macromonomers constructed from polystyrene and polyisoprene forming block copolymer HyperMacs termed HyperBlocks. Characterisation of the materials above involved techniques including rheology, thermal analysis including differential scanning caliorimetry, (DSC), and dynamic mechanical analysis, (DMA), x-ray scattering (small angle x-ray scattering, SAXS) and transition electron microscopy, (TEM).Melt rheology showed polystyrene HyperMacs to be thermorheologically simple and HyperMacs showed little evidence for relaxation by reptation. Their rheological behaviour agreed well with the Cayley tree model for hierarchical relaxation in tube models of branched polymers. HyperBlocks showed phase separated morphologies with two distinct glass transition temperatures for their constituents. However the highly branched architecture of HyperBlocks disrupts long-range order seen in the macromonomers, as observed by SAXS and TE

The Effects of Character Education on Social-Emotional Behavior

The addition of character education to school curricula has become an increasingly popular response to today’s heightened emphasis for students to succeed on academic high stake tests, leaving little regard for the development of social-emotional competencies. The purpose of this research was to study the effects of character education on the social-emotional behavior of elementary students in a private Montessori school. The study consisted of 18 students in a grade 1-4 classroom over a period of five weeks. Data was collected through daily tallying of negative behavior and through incident forms as well as student pre- and post-test evaluations regarding self and social awareness. Findings indicated that negative behaviors decreased overall and that student understanding of values improved. In addition, the data also indicated that there remains a need for character education to continue for more definitive results

Standing Swells Surveyed Showing Surprisingly Stable Solutions for the Lorenz '96 Model

The Lorenz '96 model is an adjustable dimension system of ODEs exhibiting chaotic behavior representative of dynamics observed in the Earth's atmosphere. In the present study, we characterize statistical properties of the chaotic dynamics while varying the degrees of freedom and the forcing. Tuning the dimensionality of the system, we find regions of parameter space with surprising stability in the form of standing waves traveling amongst the slow oscillators. The boundaries of these stable regions fluctuate regularly with the number of slow oscillators. These results demonstrate hidden order in the Lorenz '96 system, strengthening the evidence for its role as a hallmark representative of nonlinear dynamical behavior.Comment: 10 pages, 8 figure

Twitter reciprocal reply networks exhibit assortativity with respect to happiness

The advent of social media has provided an extraordinary, if imperfect, 'big data' window into the form and evolution of social networks. Based on nearly 40 million message pairs posted to Twitter between September 2008 and February 2009, we construct and examine the revealed social network structure and dynamics over the time scales of days, weeks, and months. At the level of user behavior, we employ our recently developed hedonometric analysis methods to investigate patterns of sentiment expression. We find users' average happiness scores to be positively and significantly correlated with those of users one, two, and three links away. We strengthen our analysis by proposing and using a null model to test the effect of network topology on the assortativity of happiness. We also find evidence that more well connected users write happier status updates, with a transition occurring around Dunbar's number. More generally, our work provides evidence of a social sub-network structure within Twitter and raises several methodological points of interest with regard to social network reconstructions.Comment: 22 pages, 21 figures, 5 tables, In press at the Journal of Computational Scienc