Symmetric motifs in random geometric graphs

We study symmetric motifs in random geometric graphs. Symmetric motifs are subsets of nodes which have the same adjacencies. These subgraphs are particularly prevalent in random geometric graphs and appear in the Laplacian and adjacency spectrum as sharp, distinct peaks, a feature often found in real-world networks. We look at the probabilities of their appearance and compare these across parameter space and dimension. We then use the Chen-Stein method to derive the minimum separation distance in random geometric graphs which we apply to study symmetric motifs in both the intensive and thermodynamic limits. In the thermodynamic limit the probability that the closest nodes are symmetric approaches one, whilst in the intensive limit this probability depends upon the dimension.Comment: 11 page

NOC turbulence glider deployment report for the Liverpool Bay Coastal Observatory, June 2011 deployment

A summary of the NOC Liverpool turbulence glider deployment that occurred between Tuesday 28th June and Monday 4th July 2011 is provided in this document. The general objective of the deployment was to hold the glider on station at a nominal GPS location of 53o 48”N, -4o 00”W to provide a series of glider based turbulence probe and CTD data profiles. These profiles were initiated when the glider reached a nominal depth of 40 metres and continued until the glider approached the sea surface. The glider deployment site was selected to be away from the influence of fresh water influx into the Liverpool Bay and in a position that avoids scheduled shipping routes. The recorded glider data was compared with a seabed instrumentation frame that was deployed at the same nominal location. The instrumentation frame had a Seabird CTD and a 5 axis upward measuring ADCP with a vertical turbulence measurement capability installed. During the glider deployment cruise reference water samples and independent CTD measurements were collected for deployed instrumentation and glider sensor calibration purpose

Underpricing, underperformance and overreaction in initial public offerings : evidence from investor attention using online searches

Online activity of Internet users has proven very useful in modeling various phenomena across a wide range of scientific disciplines. In our study, we focus on two stylized facts or puzzles surrounding the initial public offerings (IPOs) - the underpricing and the long-term underperformance. Using the Internet searches on Google, we proxy the investor attention before and during the day of the offering to show that the high attention IPOs have different characteristics than the low attention ones. After controlling for various effects, we show that investor attention still remains a strong component of the high initial returns (the underpricing), primarily for the high sentiment periods. Moreover, we demonstrate that the investor attention partially explains the overoptimistic market reaction and thus also a part of the long-term underperformance

NOC Liverpool Unit 117 Glider deployment report for the DEFRA MAREMAP Project, April - May 2012 deployment

This document summarises the extended deployment of a 200 metre depth rated Slocum Electric glider by the National Oceanography Centre, Liverpool, UK from the 2nd April to 17th May 2012. The deployment was aimed as a pilot study for the use of gliders by environment agencies to monitor marine conservation zones. Lithium expendable batteries were used inside the glider to provide an extended endurance. The glider had a series of science sensors installed to measure physical oceanographic and biological parameters that included water quality and algal activity. The glider was deployed from the Liverpool Bay and successfully navigated to the intended survey area that was more than 100km from the initial deployment location. Extensive independent scientific measurements were taken during the glider deployment and subsequent operation. These measurements were used for glider sensor calibration and the monitoring of any sensor drift. Avoidance and managing of the many hazards typical in the survey area such as shipping, strong tidal currents and fixed platforms were required during the deployment. This was achieved by remotely piloting the glider with using a satellite based communications link. After a deployment of just over six weeks a suspected glider entanglement close to the seabed occurred during a routine survey dive and attempted subsequent climb underwater. This compromised the glider operation during its return to shallower, more sheltered coastal waters for an intended recovery. An emergency recovery was then required that used a small charted deep sea fishing vessel. This document provides an overview of the deployment requirements, the glider operations and the recovered glider initial evaluation. A summary of the results achieved is also provided in the report

On Holiday! Policy and provision for disabled children and their families

This summary describes some findings from the On Holiday! study, carried out by the Thomas Coram Research Unit between 2004 and 2006 and funded by DfES. The study investigated the experiences of disabled children and their families outside school time and especially during the school holidays. The study took an approach informed by a social model of disability, one which emphasises the social construction of disability, rather than impairment

Linear and fractal diffusion coefficients in a family of one dimensional chaotic maps

We analyse deterministic diffusion in a simple, one-dimensional setting consisting of a family of four parameter dependent, chaotic maps defined over the real line. When iterated under these maps, a probability density function spreads out and one can define a diffusion coefficient. We look at how the diffusion coefficient varies across the family of maps and under parameter variation. Using a technique by which Taylor-Green-Kubo formulae are evaluated in terms of generalised Takagi functions, we derive exact, fully analytical expressions for the diffusion coefficients. Typically, for simple maps these quantities are fractal functions of control parameters. However, our family of four maps exhibits both fractal and linear behavior. We explain these different structures by looking at the topology of the Markov partitions and the ergodic properties of the maps.Comment: 21 pages, 19 figure