Fractal Patterns of Coral Communities: Evidence from Remote Sensing (Arabian Gulf, Dubai, U.A.E.)

In this study, the spatial character of benthic communities is investigated in an Arabian Gulf shallow subtidal carbonate ramp setting, using IKONOS satellite imagery. The patchy distribution of three assemblages of live and dead corals on extensive (but also fragmented) hardground pavements was investigated using a variety of spatial statistics. It was found that the spatial expression of the benthic groups display characteristics that approximate to power-law distributions over several orders of magnitude to an extent that suggests fractal behaviour. Pronounced anisotropy was observed between the spatial patterns in the near-shore and off-shore region which is attributed to different mechanisms of patch formation controlled by the local hydrodynamic regime. The study area is know to be subjected to recurrent and cyclic thermal induced mass mortality events on a decadal time scale, inhibiting reef framework development and likely to be a controlling mechanism in the patchiness of the benthic communities

Spatial Patterns in Arabian Gulf Coral Assemblages (Jebel Ali, Dubai, U.A.E.) in Response to Temperature-Forcing

We evaluated spatial and temporal patterns using maps from Ikonos satellite imagery in combination with 8 years of line transects and photosquares and the HadISST1 sea-surface temperature data set to explain why coral assemblages in the southern Arabian Gulf (Dubai) are impoverished and mostly do not build framework reefs. Analysis of archive sea surface temperature (SST) data confirms that the area is subjected to recurrent temperature anomalies. Frequencies of anomalies might suggest at least a partial link to the El Niño Southern Oscillation possibly via the Indian Ocean Zonal Mode. The dominant driver of local temperature was oscillations in the position of the subtropical jetstream. Classification of IKONOS satellite data showed that the spatial expression of four coral assemblages was consistent with reef development on a (multi-)decadal time-scale following recurring episodes of coral mass mortality induced by severe SST anomalies. Merging a remotely sensed map of substrate distribution with a detailed bathymetric digital elevation model revealed no evidence of significant framework development, suggesting that the cycle of temperature induced mortality has been operating for a considerable time

UK directors' trading: the impact of dealings in smaller firms

This paper reassesses the UK results of significant abnormal returns from directors' trading for a new sample of directors' trades 1984-1986, and finds that abnormal returns tend to be concentrated in smaller firms. When an appropriate benchmark portfolio is used, it is found that the significance of the abnormal returns is substantially reduced, with the implication that directors' trading does not yield particularly high profits to either the directors themselves or to an outside investor mimicking those trades

The development of a web service utilising open-source software to identify safer routes to school

Many parents believe the journey to school and so opt to drive their children instead of letting them either walk or cycle. In order to change parent’s opinions and increase the proportion of children who travel to school by means active transport, local authorities looking for ways that require a short time to implement, are inexpensive and applicable to all schools in their area. For this project a web service was developed, utilising open source software, which allows parents and pupils to identify safer routes to school. The data used in the study had to be easily accessible by local authorities so that the methods presented would be possible to replicate in their respective areas. Safety was firstly evaluated over the entirety of a network based on the factors street lighting, vehicle speed, accident risk and crime which were weighted using a pairwise comparison method. The network was stored in a PostgreSQL database along with shapefiles containing the locations of schools and their respective catchment areas. pgRouting was the routing software used. The webpage was based on HTML pages served by JavaScript and a Perl processing script retrieving the route optimised for safety from the PostgreSQL database. This paper provides a solution to increase the proportion of pupils who travel by active transport to school that requires a short time to implement, is inexpensive and is applicable to all schools in the area managed by a local authority