Programmable active pixel sensor to investigate neural interactions within the retina

Detection of the visual scene by the eye and the resultant neural interactions of the retina-brain system give us our perception of sight. We have developed an Active Pixel Sensor (APS) to be used as a tool for both furthering understanding of these interactions via experimentation with the retina and to make developments towards a realisable retinal prosthesis. The sensor consists of 469 pixels in a hexagonal array. The pixels are interconnected by a programmable neural network to mimic lateral interactions between retinal cells. Outputs from the sensor are in the form of biphasic current pulse trains suitable to stimulate retinal cells via a biocompatible array. The APS will be described with initial characterisation and test results

Seismometer Detection of Dust Devil Vortices by Ground Tilt

We report seismic signals on a desert playa caused by convective vortices and dust devils. The long-period (10-100s) signatures, with tilts of ~10$^{-7}$ radians, are correlated with the presence of vortices, detected with nearby sensors as sharp temporary pressure drops (0.2-1 mbar) and solar obscuration by dust. We show that the shape and amplitude of the signals, manifesting primarily as horizontal accelerations, can be modeled approximately with a simple quasi-static point-load model of the negative pressure field associated with the vortices acting on the ground as an elastic half space. We suggest the load imposed by a dust devil of diameter D and core pressure {\Delta}Po is ~({\pi}/2){\Delta}PoD$^2$, or for a typical terrestrial devil of 5 m diameter and 2 mbar, about the weight of a small car. The tilt depends on the inverse square of distance, and on the elastic properties of the ground, and the large signals we observe are in part due to the relatively soft playa sediment and the shallow installation of the instrument. Ground tilt may be a particularly sensitive means of detecting dust devils. The simple point-load model fails for large dust devils at short ranges, but more elaborate models incorporating the work of Sorrells (1971) may explain some of the more complex features in such cases, taking the vortex winds and ground velocity into account. We discuss some implications for the InSight mission to Mars.Comment: Contributed Article for Bulletin of the Seismological Society of America, Accepted 29th August 201

Applications of control theory

Applications of control theory are considered in the areas of decoupling and wake steering control of submersibles, a method of electrohydraulic conversion with no moving parts, and socio-economic system modelling

Construction management contracts: law and practice

The context of construction management (CM) reveals that this method of procurement is as much a management philosophy as a contract structure. It is important to consider legal and contractual issues in this context. The interplay between management and law is complex and often misunderstood. Before considering specific issues, the use of contractual remedies in business agreements is discussed. In addition, the extent to which standardising a form of contract detracts or contributes to the success of projects is also considered. The dearth of judicial decisions, and the lack of a standard form, render it difficult to be specific about legal issues. Therefore, the main discussion of legal issues is centred around a recently completed research project which involved eliciting the views of a cross-section of experienced construction management clients, consultants and trade contractors. These interviews are used as the basis for highlighting some of the most important legal points to consider when setting up CM projects. The interviews revealed that the advantage of CM is the proximity of the client to the trade contractors and the disadvantage is that it depends on a high degree of professionalism and experience; qualities which are unfortunately difficult to find in the UK construction industry

Fourier transform pure nuclear quadrupole resonance by pulsed field cycling

We report the observation of Fourier transform pure NQR by pulsed field cycling. For deuterium, well resolved spectra are obtained with high sensitivity showing the low frequency nu0 lines and allowing assignments of quadrupole couplings and asymmetry parameters to inequivalent deuterons. The technique is ideally applicable to nuclei with low quadrupolar frequencies (e.g., 2D, 7Li, 11B, 27Al, 23Na, 14N) and makes possible high resolution structure determination in polycrystalline or disordered materials

G-protein-coupled receptors for free fatty acids: nutritional and therapeutic targets

It is becoming evident that nutrients and metabolic intermediates derived from such nutrients regulate cellular function by activating a number of cell-surface G-protein coupled receptors (GPCRs). Until now, members of the GPCR family have largely been considered as the molecular targets that communicate cellular signals initiated by hormones and neurotransmitters. Recently, based on tissue expression patterns of these receptors and the concept that they may elicit the production of a range of appetite- and hunger-regulating peptides, such nutrient sensing GPCRs are attracting considerable attention due to their potential to modulate satiety, improve glucose homeostasis and supress the production of various pro-inflammatory mediators. Despite the developing interests in these nutrients sensing GPCR both as sensors of nutritional status, and targets for limiting the development of metabolic diseases, major challenges remain to exploit their potential for therapeutic purposes. Mostly, this is due to limited characterisation and validation of these receptors because of paucity of selective and high-potency/affinity pharmacological agents to define the detailed function and regulation of these receptors. However, ongoing clinical trials of agonists of free fatty acid receptor 1 suggest that this receptor and other receptors for free fatty acids may provide a successful strategy for controlling hyperglycaemia and providing novel approaches to treat diabetes. Receptors responsive to free fatty acid have been of particular interest, and some aspects of these are considered herein

Ontological arguments from experience: Daniel A. Dombrowski, Iris Murdoch, and the nature of divine reality

Dombrowski and Murdoch offer versions of the ontological argument which aim to avoid two types of objection - those concerned with the nature of the divine, and those concerned with the move from an abstract concept to a mind-independent reality. For both, the nature of the concept of God/Good entails its instantiation, and both supply a supporting argument from experience. It is only Murdoch who successfully negotiates the transition from an abstract concept to the instantiation of that concept, however, and this is achieved by means of an ontological argument from moral experience which, in a reversal of the Kantian doctrine, depends ultimately on a form of the cosmological argument