1,717 research outputs found
Numerical and asymptotic solutions of generalised Burgersā equation
The generalised Burgersā equation has been subject to a considerable amount of research on how the equation should behave according to asymptotic analysis, however there has been limited research verifying the asymptotic analysis. In order to verify the asymptotic analysis, this paper aims to run long time and detailed numerical simulations of Burgersā equation by employing suitable rescalings of Burgersā equation. It is hoped that this technique will make it possible to notice subtle changes in the shock structure which would otherwise be impossible to observe. The main aim of this paper is to validate the numerical methods used in order to allow further research into shock evolution where further relaxation effects will be included
A Multiple Migration and Stacking Algorithm Designed for Land Mine Detection
This paper describes a modification to a standard migration algorithm for land mine detection with a ground-penetrating radar (GPR) system. High directivity from the antenna requires a significantly large aperture in relation to the operating wavelength, but at the frequencies of operation of GPR, this would result in a large and impractical antenna. For operator convenience, most GPR antennas are small and exhibit low directivity and a wide beamwidth. This causes the GPR image to bear little resemblance to the actual target scattering centers. Migration algorithms attempt to reduce this effect by focusing the scattered energy from the source reflector and consequentially improve the target detection rate. However, problems occur due to the varying operational conditions, which result in the migration algorithm requiring vastly different calibration parameters. In order to combat this effect, this migration scheme stacks multiple versions of the same migrated data with different velocity values, whereas some other migration schemes only use a single velocity value
Analysis of the human diseasome reveals phenotype modules across common, genetic, and infectious diseases
Phenotypes are the observable characteristics of an organism arising from its
response to the environment. Phenotypes associated with engineered and natural
genetic variation are widely recorded using phenotype ontologies in model
organisms, as are signs and symptoms of human Mendelian diseases in databases
such as OMIM and Orphanet. Exploiting these resources, several computational
methods have been developed for integration and analysis of phenotype data to
identify the genetic etiology of diseases or suggest plausible interventions. A
similar resource would be highly useful not only for rare and Mendelian
diseases, but also for common, complex and infectious diseases. We apply a
semantic text- mining approach to identify the phenotypes (signs and symptoms)
associated with over 8,000 diseases. We demonstrate that our method generates
phenotypes that correctly identify known disease-associated genes in mice and
humans with high accuracy. Using a phenotypic similarity measure, we generate a
human disease network in which diseases that share signs and symptoms cluster
together, and we use this network to identify phenotypic disease modules
Shieling activity in the Norse Eastern Settlement : palaeoenvironment of the 'Mountain Farm', Vatnahverfi, Greenland
Peer reviewedPostprin
The biogeographical status of Alnus crispa (Ait.) Pursch in sub-Arctic southern Greenland : Do pollen records indicate local populations during the past 1500 years?
The Leverhulme Trust is thanked for financial support. We also thank the referees for their constructive comments that helped to improve the paper.Peer reviewedPostprin
Competing hypotheses, ordination and pollen preservation : landscape impacts of Norse landnƔm in southern Greenland
We thank the Leverhulme Trust for financial support, and Gordon Cook and staff at SUERC for the provision of radiocarbon dates. We are grateful to two anonymous reviewers and Shinya Sugita for valuable comments which improved the manuscript.Peer reviewedPostprin
A multiple profile approach to the palynological reconstruction of Norse landscapes in Greenland's Eastern Settlement
Acknowledgments The Leverhulme Trust is thanked for financial support. Gordon Cook provided radiocarbon dates. Thanks are also due to Andy McMullen for botanical identifications and assistance in the field, and to Sikuu Motzfeld for hospitality during fieldwork. We are also grateful to Emilie Gauthier, Mike Kaplan, Pete Langdon and Alan Gillespie for their comments.Peer reviewedPostprin
Interaction Correction of Conductivity Near a Ferromagnetic Quantum Critical Point
We calculate the temperature dependence of conductivity due to interaction
correction for a disordered itinerant electron system close to a ferromagnetic
quantum critical point which occurs due to a spin density wave instability. In
the quantum critical regime, the crossover between diffusive and ballistic
transport occurs at a temperature ,
where is the parameter associated with the Landau damping of the spin
fluctuations, is the impurity scattering time, and is the Fermi
energy. For a generic choice of parameters, is few orders of
magnitude smaller than the usual crossover scale . In the ballistic
quantum critical regime, the conductivity has a temperature
dependence, where is the dimensionality of the system. In the diffusive
quantum critical regime we get dependence in three dimensions, and
dependence in two dimensions. Away from the quantum critical regime
we recover the standard results for a good metal.Comment: 15 pages, 8 figure
āThe Most Awkward Building in Englandā? : The Rotten Heritage of āTin Pan Alleyā Revisited
Abstract</jats:p
- ā¦