Time and M-theory

We review our recent proposal for a background independent formulation of a holographic theory of quantum gravity. The present review incorporates the necessary background material on geometry of canonical quantum theory, holography and spacetime thermodynamics, Matrix theory, as well as our specific proposal for a dynamical theory of geometric quantum mechanics, as applied to Matrix theory. At the heart of this review is a new analysis of the conceptual problem of time and the closely related and phenomenologically relevant problem of vacuum energy in quantum gravity. We also present a discussion of some observational implications of this new viewpoint on the problem of vacuum energy.Comment: 86 pages, 5 figures, LaTeX, typos fixed, references added, and Sec. 6.2 revised; invited review for Int. J. Mod. Phys.

Image retrieval by hypertext links

This paper presents a model for retrieval of images from a large World Wide Web based collection. Rather than considering complex visual recognition algorithms, the model presented is based on combining evidence of the text content and hypertext structure of the Web. The paper shows that certain types of query are amply served by this form of representation. It also presents a novel means of gathering relevance judgements

Assessing the effectiveness of multi-touch interfaces for DP operation

Navigating a vessel using dynamic positioning (DP) systems close to offshore installations is a challenge. The operator's only possibility of manipulating the system is through its interface, which can be categorized as the physical appearance of the equipment and the visualization of the system. Are there possibilities of interaction between the operator and the system that can reduce strain and cognitive load during DP operations? Can parts of the system (e.g. displays) be physically brought closer to the user to enhance the feeling of control when operating the system? Can these changes make DP operations more efficient and safe? These questions inspired this research project, which investigates the use of multi-touch and hand gestures known from consumer products to directly manipulate the visualization of a vessel in the 3D scene of a DP system. Usability methodologies and evaluation techniques that are widely used in consumer market research were used to investigate how these interaction techniques, which are new to the maritime domain, could make interaction with the DP system more efficient and transparent both during standard and safety-critical operations. After investigating which gestures felt natural to use by running user tests with a paper prototype, the gestures were implemented into a Rolls-Royce DP system and tested in a static environment. The results showed that the test participants performed significantly faster using direct gesture manipulation compared to using traditional button/menu interaction. To support the results from these tests, further tests were carried out. The purpose is to investigate how gestures are performed in a moving environment, using a motion platform to simulate rough sea conditions. The key results and lessons learned from a collection of four user experiments, together with a discussion of the choice of evaluation techniques will be discussed in this paper

Towards high quality text entry on smartwatches

Smartwatches now provide users with access to many applications on smartphones direct from their wrists, without the need to touch their smartphone. While applications such as email, messaging, calendar and social networking provide views on the watch, there is normally no text entry method so users cannot reply on the same device. Here we introduce requirements for smartwatch text entry, an optimised alphabetic layout and present a prototype implementation together with preliminary user feedback. While raising some problems, the feedback gives indicates that reasonable quality and speed is achievable on a smartwatch and encourages our future work

The Role of Starbursts in the Formation of Galaxies & Active Galactic Nuclei

Starbursts are episodes of intense star-formation in the central regions of galaxies, and are the sites of roughly 25% of the high-mass star-formation in the local universe. In this contribution I review the role starbursts play in the formation and evolution of galaxies, the intergalactic medium, and active galactic nuclei. Four major conclusions are drawn. 1) Starburst galaxies are good analogues (in fact, the only plausible local analogues) to the known population of star-forming galaxies at high-redshift. 2) Integrated over cosmic time, supernova-driven galactic-winds (`superwinds') play an essential role in the evolution of galaxies and the inter-galactic medium. 3) Circumnuclear starbursts are an energetically-significant component of the Seyfert phenomenon. 4) The evolution of the population of the host galaxies of radio-quiet quasars is significantly different than that of powerful radio galaxies, and is at least qualitatively consistent with the standard picture of the hierarchical assembly of massive galaxies at relatively late times.Comment: 16 pages, 4 figures, Royal Society discussion meeting `The formation of galaxies

The final two redshifts for radio sources from the equatorial BRL sample

Best, Rottgering and Lehnert (1999, 2000a) defined a new sample of powerful radio sources from the Molonglo Reference Catalogue, for which redshifts were compiled or measured for 177 of the 178 objects. For the final object, MRC1059-010 (3C249), the host galaxy is here identified using near-infrared imaging, and the redshift is determined from VLT spectroscopy. For one other object in the sample, MRC0320+053 (4C05.14), the literature redshift has been questioned: new spectroscopic observations of this object are presented, deriving a corrected redshift. With these two results, the spectroscopic completeness of this sample is now 100%. New redshifts are also presented for PKS0742+10 from the Wall & Peacock 2.7 GHz catalogue, and PKS1336+003 from the Parkes Selected Regions. PKS0742+10 shows a strong neutral hydrogen absorption feature in its Lyman-alpha emission profile.Comment: 4 pages. LaTeX. Accepted for publication in MNRA

Quasars, their host galaxies, and their central black holes

We present the final results from our deep HST imaging study of the hosts of radio-quiet quasars (RQQs), radio-loud quasars (RLQs) and radio galaxies (RGs). We describe new WFPC2 R-band observations for 14 objects and model these images in conjunction with the data already reported in McLure et al (1999). We find that spheroidal hosts become more prevalent with increasing nuclear luminosity such that, for nuclear luminosities M_V < -23.5, the hosts of both radio-loud and radio-quiet AGN are virtually all massive ellipticals. Moreover we demonstrate that the basic properties of these hosts are indistinguishable from those of quiescent, evolved, low-redshift ellipticals of comparable mass. This result kills any lingering notion that radio-loudness is determined by host-galaxy morphology, and also sets severe constraints on evolutionary schemes which attempt to link low-z ULIRGs with RQQs. Instead, we show that our results are as expected given the relationship between black-hole and spheroid mass established for nearby galaxies, and apply this relation to estimate the mass of the black hole in each object. The results agree very well with completely-independent estimates based on nuclear emission-line widths; all the quasars in our sample have M(bh) > 5 x 10^8 solar masses, while the radio-loud objects are confined to M(bh) > 10^9 solar masses. This apparent mass-threshold difference, which provides a natural explanation for why RQQs outnumber RLQs by a factor of 10, appears to reflect the existence of a minimum and maximum level of black-hole radio output which is a strong function of black-hole mass. Finally, we use our results to estimate the fraction of massive spheroids/black-holes which produce quasar-level activity. This fraction is \~0.1% at the present day, rising to > 10% at z = 2-3.Comment: Revised version accepted for publication in Monthly Notices of the Royal Astronomical Society. 46 pages, the final 19 of which comprise an Appendix. 15 figures in main text. A further 14 4-panel greyscale plots and 14 line plots which appear in the Appendix have been reproduced here with reduced quality due to space limitations. A full resolution copy of the manuscript can be obtained via ftp://ftp.roe.ac.uk/pub/jsd/dunlop2002.ps.g

Changing Fashions in Diabetes

The increasing tempo of change in outlook and way of life is a characteristic of our modern age, and our changing attitudes in medicine keep pace with the rapid metamorphosis of the intellectual and material world around us. When I was asked to write an article for Res Medica on diabetes I thought, therefore, that it might be amusing and instructive to contrast my attitude to the disorder twenty-five years ago when I was a young physician with what it is now when I am a middle-aged or elderly one, for in almost every respect the change has been revolutionary.Twenty-five years ago we regarded the pathogenesis of diabetes as being very simple, however complicated it might be to treat. We knew that the pancreatectomised animal or the animal poisoned with alloxan became diabetic and died but that it could be kept alive by the appropriate administration of insulin. Diabetes was therefore regarded as being due to a simple deficiency of the internal secretion of the pancreatic islet tissue just as primary myxoedema was due to a simple failure of the thyroid to secrete the thyroid hormone