Strategies and challenges to facilitate situated learning in virtual worlds post-Second Life

Virtual worlds can establish a stimulating environment to support a situated learning approach in which students simulate a task within a safe environment. While in previous years Second Life played a major role in providing such a virtual environment, there are now more and more alternative—often OpenSim-based—solutions deployed within the educational community. By drawing parallels to social networks, we discuss two aspects: how to link individually hosted virtual worlds together in order to implement context for immersion and how to identify and avoid “fake” avatars so people behind these avatars can be held accountable for their actions

Surrogate Assisted Optimisation for Travelling Thief Problems

The travelling thief problem (TTP) is a multi-component optimisation problem involving two interdependent NP-hard components: the travelling salesman problem (TSP) and the knapsack problem (KP). Recent state-of-the-art TTP solvers modify the underlying TSP and KP solutions in an iterative and interleaved fashion. The TSP solution (cyclic tour) is typically changed in a deterministic way, while changes to the KP solution typically involve a random search, effectively resulting in a quasi-meandering exploration of the TTP solution space. Once a plateau is reached, the iterative search of the TTP solution space is restarted by using a new initial TSP tour. We propose to make the search more efficient through an adaptive surrogate model (based on a customised form of Support Vector Regression) that learns the characteristics of initial TSP tours that lead to good TTP solutions. The model is used to filter out non-promising initial TSP tours, in effect reducing the amount of time spent to find a good TTP solution. Experiments on a broad range of benchmark TTP instances indicate that the proposed approach filters out a considerable number of non-promising initial tours, at the cost of omitting only a small number of the best TTP solutions

Exploring a Non-Minimal Sterile Neutrino Model Involving Decay at IceCube and Beyond

We study the phenomenology of neutrino decay together with neutrino oscillations in the context of eV-scale sterile neutrinos. We review the formalism of visible neutrino decay in which one of the decay products is a neutrino that potentially can be observed. We apply the formalism developed for decay to the recent sterile neutrino search performed by IceCube with TeV neutrinos. We show that for $\nu_4$ lifetime $\tau_4/m_4 \lesssim 10^{-16} {\rm eV^{-1}s}$, the interpretation of the high-energy IceCube analysis can be significantly changed.Comment: 12 pages, 7 figures. Find code at: https://github.com/arguelles/nuSQUIDSDeca

Limits and Confidence Intervals in the Presence of Nuisance Parameters

We study the frequentist properties of confidence intervals computed by the method known to statisticians as the Profile Likelihood. It is seen that the coverage of these intervals is surprisingly good over a wide range of possible parameter values for important classes of problems, in particular whenever there are additional nuisance parameters with statistical or systematic errors. Programs are available for calculating these intervals.Comment: 6 figure

Phylogeography of New Zealand’s coastal benthos

During the past 30 years, 42 molecular studies have been undertaken in New Zealand to examine the phylogeography of coastal benthic invertebrates and plants. Here, we identify generalities and/or patterns that have emerged from this research and consider the processes implicated in generating genetic structure within populations. Studies have used various molecular markers and examined taxonomic groups with a range of life histories and dispersal strategies. Genetic disjunctions have been identified at multiple locations, with the most frequently observed division occurring between northern and southern populations at the top of the South Island. Although upwelling has been implicated as a cause of this disjunction, oceanographic evidence is lacking and alternative hypotheses exist. A significant negative correlation between larval duration and genetic differentiation (r2 = 0.39, P < 0.001, n = 29) across all studies suggests that larval duration might be used as a proxy for dispersal potential. However, among taxa with short larval durations (<10 days) there was greater variability in genetic differentiation than among taxa with longer pelagic periods. This variability implies that when larval duration is short, other factors may determine dispersal and connectivity among populations. Although there has been little congruence between the phylogeographic data and recognised biogeographic regions, recent research has resolved population subdivision at finer spatial scales corresponding more closely with existing biogeographic classifications. The use of fast-evolving and ecologically significant molecular markers in hypothesis-driven research could further improve our ability to detect population subdivision and identify the processes structuring marine ecosystems