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

Teaching Indigenous children : listening to and learning from indigenous teachers

This article is based on the findings of a qualitative case study that examined the professional experiences and career pathways of fifty current and former Australian Indigenous teachers. Here, we draw on data obtained from semi-structured interviews with the teachers to highlight their knowledge in three key areas: ‘Indigenous ways of knowing’, ‘Indigenous learners’ lives beyond the classroom’ and ‘Building relationships with Indigenous students and communities’. We suggest that Indigenous teachers can potentially play important roles as teacher educators and as mentors to non-Indigenous teachers and preservice teachers. We argue that it is important for schooling systems and teacher education to create and formalise opportunities for non-Indigenous teachers and preservice teachers to listen to, and learn from their Indigenous colleagues

Modeling effects of nonbreeders on population growth estimates

Acknowledgements We thank the Beissinger lab and reviewers for helpful comments on manuscript drafts. This research was funded by a Marie Curie International Outgoing Fellowship within the 7th European Community Framework Programme (project NON- BREEDERS). The contents of this paper reflect the views of the researchers, not the views of the European Commission. Data Accessibility R-code available from the Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.t56cn (Lee, Reid & Beissinger, 2016).Peer reviewedPostprin

Short-Term H-alpha Variability in M Dwarfs

We spectroscopically study the variability of H-alpha emission in mid- to late-M dwarfs on timescales of ~0.1-1 hr as a proxy for magnetic variability. About 80% of our sample exhibits statistically significant variability on the full range of timescales probed by the observations, and with amplitude ratios in the range of ~1.2-4. No events with an order of magnitude increase in H-alpha luminosity were detected, indicating that their rate is < 0.05 /hr (95% confidence level). We find a clear increase in variability with later spectral type, despite an overall decrease in H-alpha "activity" (i.e., L_{H-alpha}/L_{bol}). For the ensemble of H-alpha variability events, we find a nearly order of magnitude increase in the number of events from timescales of about 10 to 30 min, followed by a roughly uniform distribution at longer durations. The event amplitudes follow an exponential distribution with a characteristic scale of Max(EW)/Min(EW)}-1 ~ 0.7. This distribution predicts a low rate of ~ 10^{-6} /hr for events with (Max(EW)/Min(EW) > 10, but serendipitous detections of such events in the past suggests that they represent a different distribution. Finally, we find a possible decline in the amplitude of events with durations of > 0.5 hr, which may point to a typical energy release in H-alpha events for each spectral type (E_{H-alpha} ~ L_{H-alpha} x t ~ const). Longer observations of individual active objects are required to further investigate this possibility. Similarly, a larger sample may shed light on whether H-alpha variability correlates with properties such as age or rotation velocity.Comment: Accepted for publication in Ap

Seeding for pervasively overlapping communities

In some social and biological networks, the majority of nodes belong to multiple communities. It has recently been shown that a number of the algorithms that are designed to detect overlapping communities do not perform well in such highly overlapping settings. Here, we consider one class of these algorithms, those which optimize a local fitness measure, typically by using a greedy heuristic to expand a seed into a community. We perform synthetic benchmarks which indicate that an appropriate seeding strategy becomes increasingly important as the extent of community overlap increases. We find that distinct cliques provide the best seeds. We find further support for this seeding strategy with benchmarks on a Facebook network and the yeast interactome.Comment: 8 Page

Sending Love Through A Barrel: Investigating the Immigrants’ Experience, From Belonging To Assimilation

This studio-based thesis explores the experiences of a black immigrant woman as they migrate from the Caribbean to the United States of America. An exploration through artmaking addresses the impact of these experiences on a social, economic, interpersonal, and intrapersonal relationship level. This thesis examines how the implications of these experiences affect a teaching artist’s life using them as inspirations and motivations while also discussing their impact. Not only is it impactful to a visual arts educator with these specific experiences explored as they navigate teaching, but especially also in teaching to a specific immigrant/refugee demographic of students

ALMA observations of the outflow from the Source I in the Orion-KL region

In this {\it Letter}, we present sensitive millimeter SiO (J=5-4; $\nu$=0) line observations of the outflow arising from the enigmatic object Orion Source I made with the Atacama Large Millimeter/Submillimeter Array (ALMA). The observations reveal that at scales of a few thousand AU, the outflow has a marked "butterfly" morphology along a northeast-southwest axis. However, contrary to what is found in the SiO and H$_2$O maser observations at scales of tens of AU, the blueshifted radial velocities of the moving gas are found to the northwest, while the redshifted velocities are in the southeast. The ALMA observations are complemented with SiO (J=8-7; $\nu$=0) maps (with a similar spatial resolution) obtained with the Submillimeter Array (SMA). These observations also show a similar morphology and velocity structure in this outflow. We discuss some possibilities to explain these differences at small and large scales across the flow.Comment: Accepted to ApJ

Experimentally realizable characterizations of continuous variable Gaussian states

Measures of entanglement, fidelity and purity are basic yardsticks in quantum information processing. We propose how to implement these measures using linear devices and homodyne detectors for continuous variable Gaussian states. In particular, the test of entanglement becomes simple with some prior knowledge which is relevant to current experiments.Comment: 4 pages, This paper supersedes quant-ph/020315

Full Three Dimensional Orbits For Multiple Stars on Close Approaches to the Central Supermassive Black Hole

With the advent of adaptive optics on the W. M. Keck 10 m telescope, two significant steps forward have been taken in building the case for a supermassive black hole at the center of the Milky Way and understanding the black hole's effect on its environment. Using adaptive optics and speckle imaging to study the motions of stars in the plane of sky with +-~2 mas precision over the past 7 years, we have obtained the first simultaneous orbital solution for multiple stars. Among the included stars, three are newly identified (S0-16, S0-19, S0-20). The most dramatic orbit is that of the newly identified star S0-16, which passed a mere 60 AU from the central dark mass at a velocity of 9,000 km/s in 1999. The orbital analysis results in a new central dark mass estimate of 3.6(+-0.4)x10^6(D/8kpc)^3 Mo. This dramatically strengthens the case for a black hole at the center of our Galaxy, by confining the dark matter to within a radius of 0.0003 pc or 1,000 Rsh and thereby increasing the inferred dark mass density by four orders of magnitude compared to earlier estimates. With the introduction of an adaptive-optics-fed spectrometer, we have obtained the spectra of these high-velocity stars, which suggest that they are massive (~15 Mo), young (<10 Myr) main sequence stars. This presents a major challenge to star formation theories, given the strong tidal forces that prevail over all distances reached by these stars in their current orbits and the difficulty in migrating these stars inward during their lifetime from further out where tidal forces should no longer preclude star formation.Comment: 7 pages, 5 figures (abridged abstract

Accelerating U.S. Clean Energy Deployment: Investor Policy Priorities

International investment to mitigate climate change is far below levels needed to reach the two-degree target. The International Energy Agency estimates that an average of an additional $1 trillion in incremental financing for clean energy is needed to meet the temperature target. In September 2014, over 350 investors representing$24 trillion in assets issued the Global Investor Statement on Climate Change, calling on governments to create an ambitious global agreement that includes a meaningful price on carbon -- the "Clean Trillion."This paper connects the Clean Trillion goal to the current United States climate and clean energy policy framework, which is a mixture of federal, state, and local initiatives. The paper outlines the 2015 U.S. policy priorities of the Policy Working Group of the Investor Network on Climate Risk (INCR), a network of more than 110 institutional investors primarily based in the U.S., focused on investment risks and opportunities associated with climate change