Extended attention span training system

Attention Deficit Disorder (ADD) is a behavioral disorder characterized by the inability to sustain attention long enough to perform activities such as schoolwork or organized play. Treatments for this disorder include medication and brainwave biofeedback training. Brainwave biofeedback training systems feed back information to the trainee showing him how well he is producing the brainwave pattern that indicates attention. The Extended Attention Span Training (EAST) system takes the concept a step further by making a video game more difficult as the player's brainwaves indicate that attention is waning. The trainee can succeed at the game only by maintaining an adequate level of attention. The EAST system is a modification of a biocybernetic system that is currently being used to assess the extent to which automated flight management systems maintain pilot engagement. This biocybernetic system is a product of a program aimed at developing methods to evaluate automated flight deck designs for compatibility with human capabilities. The EAST technology can make a contribution in the fields of medical neuropsychology and neurology, where the emphasis is on cautious, conservative treatment of youngsters with attention disorders

Frequency and triggering mechanisms of submarine mass movements and their geohazard implications

Submarine mass movements are one of the most important processes for moving sediment across our planet. They represent the dominant process for moving sediment in many parts of the world’s oceans, freshwater lakes and reservoirs. These flows also represent a significant geohazard. They can generate damaging tsunami and have the potential to damage strategically important seafloor infrastructure. It is therefore important to understand the frequency and triggering mechanisms of these events. This thesis aims to further our understanding using a variety of different data types (artificial data, deposits found in cores, seismic stratigraphy and submarine cable breaks) across different spatial scales. First, artificial data is used to analyse the impacts of large age uncertainties on identifying a triggering mechanism for large (>1 km3) landslides in a global database. It is shown that the size of age uncertainties, the small number of landslides within the database and the combination of multiple different settings into one dataset will likely result in landslides appearing to occur randomly. As a result it is suggested that it is prudent to focus on well-dated landslides from one setting with similar triggers rather than having a poorly calibrated understanding of landslide ages in multiple settings which may prevent a trigger being identified. Second, a global database of subsea fibre optic cable breaks is used to investigate the triggering of submarine mass movements by earthquakes and tropical cyclones. Globally earthquakes between Mw 3 and Mw 9.2 are shown to trigger mass movements. However, in contrast to previous assertions it is shown that there is not a specific earthquake magnitude that will systematically trigger mass movements capable of breaking a cable. The susceptibility of slopes to fail as a consequence of large and small earthquakes is dependent on the average seismicity of the region and the volume of sediment supplied annually to the continental shelf. The frequency of damaging tropical cyclone triggered submarine mass movements is lower than earthquake triggered mass movements. Analysis of the cable break database reveals three mechanisms by which mass movements are triggered. First, tropical cyclones trigger flows directly, synchronous to their passage due to dynamic loading of the seabed. Second, flows are triggered indirectly, as a consequence of peak flood discharges delivering large volumes of sediment to the continental shelf. Third, flows are triggered indirectly following a delay as a consequence of the large volumes of rapidly deposited sediment that occurs after the passage of a tropical cyclone. No clear global relationship between future climate change and flow frequency is shown, however, changes to cyclone activity in specific regions appears likely to increase damaging flow frequency. Third, using a new piston core dataset, the timing and frequency of glacigenic debris-flows on the Bear Island Trough-Mouth Fan is investigated. The timing of glacigenic debris-flows over the last 140,000 years is shown to be controlled by the presence of an ice stream close to the shelf edge. Moreover, it is shown that the frequency and volumes of these flows is controlled by the overall dynamics of the Barents Sea Ice Sheet which vary significantly over the 140,000 year time period. Last, a review of the relationship between ice sheets and submarine mass movements around the Nordic Seas over the Quaternary is presented using published seismic and sediment core datasets. From these data sources, the growth and decay histories of the Greenland, Barents Sea and Scandinavian Ice Sheets are tracked relative to the different types of submarine mass movements identified on their margins. The type and frequency of submarine mass movement is shown to be highly variable as a consequence of variable ice sheet extent, rates of sediment transport and meltwater export of sediment. These records have allowed the identification of first order controls on sediment delivery to continental margins at ice sheet scales. It has also enabled updated conceptual models of trough-mouth fan processes, glaciated margin development and submarine landslide occurrence to be developed

The stability of buoyant bubbles in the atmospheres of galaxy clusters

The buoyant rise of hot plasma bubbles inflated by active galactic nuclei outflows in galaxy clusters can heat the cluster gas and thereby compensate radiative energy losses of this material. Numerical simulations of this effect often show the complete disruption of the bubbles followed by the mixing of the bubble material with the surrounding cluster gas due to fluid instabilities on the bubble surface. This prediction is inconsistent with the observations of apparently coherent bubble structures in clusters. We derive a general description in the linear regime of the growth of instabilities on the surface between two fluids under the influence of a gravitational field, viscosity, surface tension provided by a magnetic field and relative motion of the two fluids with respect to each other. We demonstrate that Kelvin–Helmholtz instabilities are always suppressed, if the fluids are viscous. They are also suppressed in the inviscid case for fluids of very different mass densities. We show that the effects of shear viscosity as well as a magnetic field in the cluster gas can prevent the growth of Rayleigh–Taylor instabilities on relevant scalelengths. Rayleigh–Taylor instabilities on parsec scales are suppressed even if the kinematic viscosity of the cluster gas is reduced by two orders of magnitude compared to the value given by Spitzer for a fully ionized, unmagnetized gas. Similarly, magnetic fields exceeding a few ?G result in an effective surface tension preventing the disruption of bubbles. For more massive clusters, instabilities on the bubble surface grow faster. This may explain the absence of thermal gas in the north-west bubble observed in the Perseus cluster compared to the apparently more disrupted bubbles in the Virgo cluster

Eye shape and retinal shape, and their relation to peripheral refraction

Purpose: We provide an account of the relationships between eye shape, retinal shape and peripheral refraction. Recent findings: We discuss how eye and retinal shapes may be described as conicoids, and we describe an axis and section reference system for determining shapes. Explanations are given of how patterns of retinal expansion during the development of myopia may contribute to changing patterns of peripheral refraction, and how pre-existing retinal shape might contribute to the development of myopia. Direct and indirect techniques for determining eye and retinal shape are described, and results are discussed. There is reasonable consistency in the literature of eye length increasing at a greater rate than height and width as the degree of myopia increases, so that eyes may be described as changing from oblate/spherical shapes to prolate shapes. However, one study indicates that the retina itself, while showing the same trend, remains oblate in shape for most eyes (discounting high myopia). Eye shape and retinal shape are not the same and merely describing an eye shape as being prolate or oblate is insufficient without some understanding of the parameters contributing to this; in myopia a prolate eye shape is likely to involve both a steepening retina near the posterior pole combined with a flattening (or a reduction in steepening compared with an emmetrope) away from the pole

Method of encouraging attention by correlating video game difficulty with attention level

A method of encouraging attention in persons such as those suffering from Attention Deficit Disorder is provided by correlating the level of difficulty of a video game with the level of attention in a subject. A conventional video game comprises a video display which depicts objects for interaction with a player and a difficulty adjuster which increases the difficulty level, e.g., action speed and/or evasiveness of the depicted object, in a predetermined manner. The electrical activity of the brain is measured at selected sites to determine levels of awareness, e.g., activity in the beta, theta, and alpha states. A value is generated based on this measured electrical signal which is indicative of the level of awareness. The difficulty level of the game is increased as the awareness level value decreases and is decreased as this awareness level value increases