Phase-lock loop frequency control and the dropout problem

Technique automatically sets the frequency of narrow band phase-lock loops within automatic lock-in-range. It presets a phase-lock loop to a desired center frequency with a closed loop electronic frequency discriminator and holds the phase-lock loop to that center frequency until lock is achieved

Leviduction-- a study in electromagnetic levitation

Imperial Users onl

Simulating star formation in molecular cloud cores IV. The role of turbulence and thermodynamics

We perform SPH simulations of the collapse and fragmentation of low-mass cores having different initial levels of turbulence (alpha_turb=0.05,0.10,0.25). We use a new treatment of the energy equation which captures the transport of cooling radiation against opacity due to both dust and gas (including the effects of dust sublimation, molecules, and H^- ions). We also perform comparison simulations using a standard barotropic equation of state. We find that -- when compared with the barotropic equation of state -- our more realistic treatment of the energy equation results in more protostellar objects being formed, and a higher proportion of brown dwarfs; the multiplicity frequency is essentially unchanged, but the multiple systems tend to have shorter periods (by a factor ~3), higher eccentricities, and higher mass ratios. The reason for this is that small fragments are able to cool more effectively with the new treatment, as compared with the barotropic equation of state. We find that the process of fragmentation is often bimodal. The first protostar to form is usually, at the end, the most massive, i.e. the primary. However, frequently a disc-like structure subsequently forms round this primary, and then, once it has accumulated sufficient mass, quickly fragments to produce several secondaries. We believe that this delayed fragmentation of a disc-like structure is likely to be an important source of very low-mass hydrogen-burning stars and brown dwarfs.Comment: 14 pages, 8 figures. Accepted for publication by A&

SCUBA observations of the Horsehead Nebula - what did the horse swallow?

We present observations taken with SCUBA on the JCMT of the Horsehead Nebula in Orion (B33), at wavelengths of 450 and 850 \mum. We see bright emission from that part of the cloud associated with the photon-dominated region (PDR) at the `top' of the horse's head, which we label B33-SMM1. We characterise the physical parameters of the extended dust responsible for this emission, and find that B33-SMM1 contains a more dense core than was previously suspected. We compare the SCUBA data with data from the Infrared Space Observatory (ISO) and find that the emission at 6.75-\mum is offset towards the west, indicating that the mid-infrared emission is tracing the PDR while the submillimetre emission comes from the molecular cloud core behind the PDR. We calculate the virial balance of this core and find that it is not gravitationally bound but is being confined by the external pressure from the HII region IC434, and that it will either be destroyed by the ionising radiation, or else may undergo triggered star formation. Furthermore we find evidence for a lozenge-shaped clump in the `throat' of the horse, which is not seen in emission at shorter wavelengths. We label this source B33-SMM2 and find that it is brighter at submillimetre wavelengths than B33-SMM1. SMM2 is seen in absorption in the 6.75-\mum ISO data, from which we obtain an independent estimate of the column density in excellent agreement with that calculated from the submillimetre emission. We calculate the stability of this core against collapse and find that it is in approximate gravitational virial equilibrium. This is consistent with it being a pre-existing core in B33, possibly pre-stellar in nature, but that it may also eventually undergo collapse under the effects of the HII region.Comment: 11 pages, 6 figures, accepted by MNRA

A psycho-legal perspective on sexual offending in individuals with Autism Spectrum Disorder

It is important to consider whether there are innate vulnerabilities that increase the risk of an individual with an autistic spectrum disorder (ASD), predominantly those defendants with a diagnosis of Asperger’s Syndrome, being charged and convicted of a sexual offence. The significance of such can be readily seen in recent English case law, with judgments on appeal finding convictions unsafe where there have been a number of failings in the Judge's summing up. In this article, we will consider the gravity of Judges omitting to highlight a defendant’s diagnosis of autism spectrum disorder and the necessity of detailed explanations to jury members regarding the condition and its effect upon thoughts and behaviour. Consideration will be specifically given to the necessity to prove sexual motivation in such offences and the judicial direction required in relation to whether the appellant's actions had been sexually motivated. Recognition of the social impairments inherent in ASDs are vital to this work and we shall consider whether the difficulty with the capacity to develop appropriate, consenting sexual relationships as a result of impaired social cognition may be one of the factors which increases the risk of sexual offending in individuals with ASD (Higgs & Carter, 2015)

The PRINTS database: a fine-grained protein sequence annotation and analysis resource—its status in 2012

The PRINTS database, now in its 21st year, houses a collection of diagnostic protein family ‘fingerprints’. Fingerprints are groups of conserved motifs, evident in multiple sequence alignments, whose unique inter-relationships provide distinctive signatures for particular protein families and structural/functional domains. As such, they may be used to assign uncharacterized sequences to known families, and hence to infer tentative functional, structural and/or evolutionary relationships. The February 2012 release (version 42.0) includes 2156 fingerprints, encoding 12 444 individual motifs, covering a range of globular and membrane proteins, modular polypeptides and so on. Here, we report the current status of the database, and introduce a number of recent developments that help both to render a variety of our annotation and analysis tools easier to use and to make them more widely available

Irish County Incomes in 1960. ESRI General Research Series Paper No. 16, September 1963

This paper owes its inception to a problem which the Taoiseach (Prime Minister), Mr. Se~n F. Lemass, T.D., at the Opening Ceremony on 6 June, 196I, asked the Institute to examine, in the following terms:-- "The Minister for Finance has already raised the questions whether the present system is adequate or appropriate to deal with the increasing activities of local bodies or whether a more rational or more effective system could be devised. There is a situation developing in local authority operations, and their financing, which requires consideration. Investigations, under the auspices of the Institute, of certain aspects, including the economic aspects, of the incidence of local taxation covering such matters as the effect of the local rate charge on enterprise and development, and the possibilities of providing Local Authorities with new sources of income, will provide some basic material which will be invaluable in the review of local finance which the Minister for Local Government intends to undertake"

Irish County Incomes in 1960. ESRI General Research Series Paper No. 16, September 1963

This paper owes its inception to a problem which the Taoiseach (Prime Minister), Mr. Se~n F. Lemass, T.D., at the Opening Ceremony on 6 June, 196I, asked the Institute to examine, in the following terms:-- "The Minister for Finance has already raised the questions whether the present system is adequate or appropriate to deal with the increasing activities of local bodies or whether a more rational or more effective system could be devised. There is a situation developing in local authority operations, and their financing, which requires consideration. Investigations, under the auspices of the Institute, of certain aspects, including the economic aspects, of the incidence of local taxation covering such matters as the effect of the local rate charge on enterprise and development, and the possibilities of providing Local Authorities with new sources of income, will provide some basic material which will be invaluable in the review of local finance which the Minister for Local Government intends to undertake"

Position-relative identities in the internet of things: An evolutionary GHT approach

The Internet of Things (IoT) will result in the deployment of many billions of wireless embedded systems creating interactive pervasive environments. It is envisaged that devices will cooperate to provide greater system knowledge than the sum of its parts. In an emergency situation, the flow of data across the IoT may be disrupted, giving rise to a requirement for machine-to-machine interaction within the remaining ubiquitous environment. Geographic hash tables (GHTs) provide an efficient mechanism to support fault-tolerant rendezvous communication between devices. However, current approaches either rely on devices being equipped with a GPS or being manually assigned an identity. This is unrealistic when the majority of these systems will be located inside buildings and will be too numerous to expect manual configuration. Additionally, when using GHT as a distributed data store, imbalance in the topology can lead to storage and routing overhead. This causes unfair work load, exhausting limited power supplies as well as causing poor data redundancy. To deal with these issues, we propose an approach that balances graph-based layout identity assignment, through the application of multifitness genetic algorithms. Our experiments show through simulation that our multifitness evolution technique improves on the initial graph-based layout, providing devices with improved balance and reachability metrics