The specificity and robustness of long-distance connections in weighted, interareal connectomes

Brain areas' functional repertoires are shaped by their incoming and outgoing structural connections. In empirically measured networks, most connections are short, reflecting spatial and energetic constraints. Nonetheless, a small number of connections span long distances, consistent with the notion that the functionality of these connections must outweigh their cost. While the precise function of these long-distance connections is not known, the leading hypothesis is that they act to reduce the topological distance between brain areas and facilitate efficient interareal communication. However, this hypothesis implies a non-specificity of long-distance connections that we contend is unlikely. Instead, we propose that long-distance connections serve to diversify brain areas' inputs and outputs, thereby promoting complex dynamics. Through analysis of five interareal network datasets, we show that long-distance connections play only minor roles in reducing average interareal topological distance. In contrast, areas' long-distance and short-range neighbors exhibit marked differences in their connectivity profiles, suggesting that long-distance connections enhance dissimilarity between regional inputs and outputs. Next, we show that -- in isolation -- areas' long-distance connectivity profiles exhibit non-random levels of similarity, suggesting that the communication pathways formed by long connections exhibit redundancies that may serve to promote robustness. Finally, we use a linearization of Wilson-Cowan dynamics to simulate the covariance structure of neural activity and show that in the absence of long-distance connections, a common measure of functional diversity decreases. Collectively, our findings suggest that long-distance connections are necessary for supporting diverse and complex brain dynamics.Comment: 18 pages, 8 figure

Study of the Outcomes and Impacts of the Global Forum on Migration and Development and Civil Society Days

In November 2011, the Global Forum on Migration and Development (GFMD) and accompanying Civil Society Days (CSD) completed their fifth year of operation, with the aim of improving migration policy coherence and enhancing the benefits of migration to sending and receiving countries, and to migrants themselves. The John D. and Catherine T. MacArthur Foundation, the largest non-governmental donor to this process, commissioned this study to retrospectively assess the outcomes and impact of the CSD and GFMD on policies, practices, issue framing, and government-civil society cooperation; and to prospectively draw lessons learned for the future of the GFMD and CSD. The evaluation took place from November 2011 through September 2012, allowing the team to observe the CSD and GFMD in Geneva, conduct an in-depth case study in Mexico, distribute online surveys to participants, conduct interviews at the UN offices in New York, and conduct key informant interviews by phone. Using a mixed method approach, combining quantitative survey data with qualitative key informant interviews and an extensive document review, the team has worked to triangulate data and strengthen the validity of findings. This study is geared towards the main stakeholders of the GFMD and CSD, including governments, civil society representatives, and donors. It is hoped that the aforementioned stakeholders will be able to utilize the findings, conclusions, and recommendations within this report to better inform their work in migration and development moving forward -- both within and outside of the GFMD and CSD processes

A model for the onset of oscillations near the stopping angle in an inclined granular flow

We propose an explanation for the onset of oscillations seen in numerical simulations of dense, inclined flows of inelastic, frictional spheres. It is based on a phase transition between disordered and ordered collisional states that may be interrupted by the formation of force chains. Low frequency oscillations between ordered and disordered states take place over weakly bumpy bases; higher-frequency oscillations over strongly bumpy bases involve the formation of particle chains that extend to the base and interrupt the phase change. The predicted frequency and amplitude of the oscillations induced by the unstable part of the equation of state are similar to those seen in the simulations and they depend upon the contact stiffness in the same way. Such oscillations could be the source of sound produced by flowing sand

New CO and Millimeter Continuum Observations of the z=2.394 Radio Galaxy 53W002

The z=2.39 radio galaxy 53W002 lies in a cluster of Ly-alpha emission line objects and may itself be undergoing a major burst of star formation. CO(3--2) emission, at 102 GHz, was detected from 53W002 by Scoville et al. (1997a), who also reported a possible 30 kpc extension and velocity gradient suggesting a rotating gaseous disk. In this paper we present new interferometric CO(3--2) observations which confirm the previous line detection with improved signal-to-noise ratio, but show no evidence for source extension or velocity gradient. The compact nature of the CO source and the molecular mass found in this object are similar to luminous infrared galaxies and other AGNs previously studied

Fed intervention: managing moral hazard in financial crises

At the end of September 2008, U.S. policymakers had been working for more than a year to contain the shock waves from plunging home prices and the subsequent financial market turmoil. For the Federal Reserve, the crisis has given new meaning to the adage that extraordinary times call for extraordinary measures. The central bank has dusted off Depression-era powers and rewritten old rules to address serious risks to the global financial system.Monetary policy - United States ; Financial crises ; Financial markets ; Federal Reserve System