Physical Sciences and Mathematics Commons^™

Experimental And Calculated Stark Widths Within The Kr I Spectrum, Vladimir Milosavljevic, Stevan Djenize, Milan S. Dimitrijevic

Articles

On the basis of the precisely recorded 20 neutral krypton (Kr I) line shapes (in the 5s−5p and 5s−6p transitions), we have obtained the basic plasma parameters, i.e., electron temperature (T) and electron density (N) using our line deconvolution procedure in a plasma created in a linear, low-pressure, pulsed arc discharge operated in krypton. The mentioned plasma parameters have also been measured using independent experimental diagnostics techniques. Agreement has been found among the two sets of the obtained parameters. This recommends our deconvolution procedure for plasma diagnostical purposes, especially in astrophysics where direct measurements of the …

Reply To "Comment On ‘Atomic Spectral Line Free-Parameter Deconvolution Procedure’”, Vladimir Milosavljevic, Goran Poparic

Articles

We do not agree with the authors of the preceding Comment [X. Nikolic, X. Ojurovic, and X. Mijatovic, Phys. Rev. E, 67, 058401, 2003]. Our numerical procedure for the deconvolution of the theoretical asymmetric convolution integral of a Gaussian and a plasma broadened spectral line profile jA,R(λ) for spectral lines enables the determination of all broadening parameters. All broadening parameters can be determined directly from the recorded line profile of a single line, with minimal assumptions or prior knowledge. Additional experimental diagnostics are not required.

The He I 706.52 Nm Line Shape Characteristics In The Plasma Diagnostics, Vladimir Milosavljevic, Stevan Djenize

Articles

On the basis of the precisely recorded 706.52 nm He I line shape we have obtained the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of five various plasmas created in a linear, low–pressure, pulsed arc discharge. Plasma parameters have been also measured using independent experimental diagnostical techniques. Excellent agreement was found among the two sets of the obtained parameters. This enables our deconvolution procedure to recommendation for plasma diagnostical purposes, especially in astrophysics where direct measurements of the plasma parameters (T and …

On-Line Spatial Processing Systems, James Carswell, Michela Bertolotto

Articles

On-line Spatial Processing (OLSP) delivers high performance spatial systems for the modelling and monitoring of dynamic environments. It provides an ideal solution for the management of networks, land and assets, and the real-time tracking of changing spatial systems. OLSP is server-centric, as opposed to the primarily desktop-centric world of GIS. It places spatial data at the heart of the organisation's IT systems and integrates it with business and attribute data. The result is more effective use of spatial data and improved decision support and spatial intelligence throughout the organisation.

Bridging The Ict Gap: A Study Of Uk Online Centres, John Cook, Matt Smith

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An initiative to create about 6,000 UK online centres aims to bridge the gap between those in society who have access to and are able to use information and communication technologies competently, and those who do not. UK online centres can be seen as networked community learning entities, playing an expanding role in formal and informal community-based learning.

The study described below provides a detailed snapshot of what was happening in UK online centres in the first nine months of 2002. The goal was to gain an improved understanding of the social context of the centres, and issues around the …

Simulation Of Dynamic Electrochemical Processes, John Cassidy

Articles

This work is designed to introduce electrochemists in a tutorial manner to the basics of modeling of electrochemical systems based primarily on diffusion equations. There is an introduction to analytical and numerical methods with examples taken from typical electrochemical experiments. The Laplace transform is used to derive the Cottrell equation and chronopotentiometry. The response of an electrode to a Gaussian concentration profile is detailed. Laplace’s equation is solved for a simple cell to determine the potential distribution. Discrete methods are employed to calculate the current time behavior following a potential step using the explicit finite difference method. Cyclic voltammetry is …

Characterization Of The Interaction Of Gamma Cyclodextrin With Single-Walled Carbon Nanotubes, Gordon Chambers, Clodagh Carroll, Garrett Farrell, Alan Dalton, Mary Mcnamara, Marc In Het Panhuis, Hugh Byrne

Articles

In this study a number of composite-like samples of ç-cyclodextrin and HiPco carbon nanotubes were prepared. The first sample was prepared by a simple grinding procedure, which has been reported to cut HiPco carbon nanotubes. The other samples were obtained via a refluxing procedure analogous to similar studies on other fullerenes and ç-cyclodextrin. The samples were analyzed using absorption and Raman spectroscopy, and differential scanning calorimetry. The results presented show clear evidence of an intermolecular interaction between ç-cyclodextrin and single-walled carbon nanotubes.

Assessment Of The Acoustic Properties Of Common Tissue-Mimicking Test Phantoms, Jacinta Browne, K. Ramnarine, A. Watson, P. Hoskins

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Ultrasound (US) test phantoms incorporating tissue-mimicking materials (TMMs) play an important role in the quality control (QC) and performance testing of US equipment. Three commercially available TMMs (ZerdineTM from CIRS Inc.; condensed-milk-based gel from Gammex RMI; urethane-rubber-based from ATS Labs) and a noncommercial agar-based TMM, were investigated. Acoustic properties were measured over the frequency range 2.25 to 15 MHz at a range of ambient temperatures (10 to 35°C). The acoustic velocity of the TMMs remained relatively constant with increasing frequency. Only the agar-based TMM had a linear increase of attenuation with frequency, with the other materials exhibiting nonlinear responses to …

Short-Term Effects Of Ambient Particles On Mortality In The Elderly: Results From 28 Cities In The Aphea2 Project, E. Aga, E. Samoli, G. Touloumi, K. Katsouyanni, H.R. Anderson, E. Cadum, B. Forsberg, Patrick J. Goodman, A. Goren, F. Kotesovec, B. Kriz, M. Macarol-Hiti, S. Medina, A. Paldy, C. Schindler, J. Sunyer, P. Tittanen, B. Wojtyniak, D. Zmirou, J. Schwartz

Articles

ABSTRACT: Within the framework of the APHEA2 (Air Pollution on Health: a European Approach) project, the effects of ambient particles on mortality among persons o65 yrs were investigated. Daily measurements for particles with a 50% cut-off aerodynamic diameter of 10 mm (PM10) and black smoke (BS), as well as the daily number of deaths among persons o65 yrs of age, from 29 European cities, have been collected. Data on other pollutants and meteorological variables, to adjust for confounding effects and data on city characteristics, to investigate potential effect modification, were also recorded. For individual city analysis, generalised additive models extending …

Ion Contribution To The Astrophysical Important 447.15, 587.56 And 667.82 Nm He I Spectral Lines Broadening, Vladimir Milosavljevic, Stevan Djenize

Articles

Characteristics of the astrophysical important Stark broadened 447.15 nm, 587.56 nm and 667.82 nm spectral line profiles have been measured at electron densities between 0.3 10 and 8.2 10 m and electron temperatures between 8000 and 33 000 K in plasmas created in five various discharge conditions using a linear, low-pressure, pulsed arc as an optically thin plasma source operated in a helium-nitrogen-oxygen gas mixture. On the basis of the observed asymmetry of the line profiles we have obtained their ion broadening parameters ( A) caused by influence of the ion microfield on the line broadening mechanism and also …

Geospatial Data Handling For Web-Based And Mobile Applications, James Carswell

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One of the main bottlenecks for web-based GIS usability is in the transmission and handling of the vast amounts of geospatial data involved. The shear volume of raster, vector, attribute, and other data to be analysed, queried, transmitted and displayed over the WWW in real-time is prohibited by connection speeds. In this paper we introduce e-Spatial technology, a fully integrated open standard web-based solution to manage multiple spatial relationships directly in an Oracle Spatial database and to deploy in real-time spatially enabled (or standard) applications completely independent of data volume. Indeed, no application code is ever installed on the client …

Stark Shifts And Transition Probabilities In The Ne Ii Spectrum, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic

Articles

Stark shifts (d) and transition probabilities of the spontaneous emission (Einstein's A values) of forty two singly charged neon ( ) ion spectral lines have been measured in a linear, low pressure, pulsed arc at 35 300 K electron temperature and 1.83 10 ²³ m ^-3 electron density. Transition probabilities have been obtained using the relative line intensity ratio (RLIR) method. Stark shift values have also been calculated, using the semiclassical perturbation formalism (SCPF). The measured and calculated shift values and the measured A values have been compared to the existing data taken from available data sources.

Rational Generalized Moonshine From Abelian Orbifoldings Of The Moonshine Module, Rossen Ivanov, Michael Tuite

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We consider orbifoldings of the Moonshine Module with respect to the abelian group generated by a pair of commuting Monster group elements with one of prime order p = 2, 3, 5, 7 and the other of order pk for k = 1 or k prime. We show that constraints arising from meromorphic orbifold conformal field theory allow us to demonstrate that each orbifold partition function with rational coefficients is either constant or is a hauptmodul for an explicitly found modular fixing group of genus zero. We thus confirm in the cases considered the Generalised Moonshine conjectures for all rational …

Scale And Orientation-Invariant Scene Similarity Metrics For Image Queries, James Carswell

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In this paper we extend our previous work on shape-based queries to support queries on configurations of image objects. Here we consider spatial reasoning, especially directional and metric object relationships. Existing models for spatial reasoning tend to rely on pre-identified cardinal directions and minimal scale variations, assumption that cannot be considered as given in our image applications, where orientations and scale may vary substantially, and are often unknown. Accordingly, we have developed the method of varying baselines to identify similarities in direction and distance relations. Our method allows us to evaluate directional similarities without a priori knowledge of cardinal directions, …

Clinical Assessment Of The Quantitative Posturography System (Qps), Jacinta Browne, G. O'Hare, A. Finn, J. Colin

Articles

The objectives of this study were to evaluate a novel design dynamic force platform the Quantitative Posturography System (QPS). The evaluation consisted of identifying the effects due to ageing and disease of the postural control system and also to examine the relationship between functional performance and postural sway. An AOVA design and Pearson-Product correlation design were used. Seventy healthy subjects, seven subjects with Parkinson’s disease and eight subjects with a history of falls took part in the study. It was found that the QPS was able to identify changes due to both the ageing process and disease on the postural …

K(Π, 1) For Artin Groups Of Finite Type, Colum Watt, Thomas Brady

Articles

This paper is a continuation of a programme to construct new K(π, 1)’s for Artin groups of finite type which began in [4] with Artin groups on 2 and 3 generators and was extended to braid groups in [3]. These K(π, 1)’s differ from those in [6] in that their universal covers are simplicial complexes. In [4] a complex is constructed whose top-dimensional cells correspond to minimal factorizations of a Coxeter element as a product of reflections in a finite Coxeter group. Asphericity is established in low dimensions using a metric of non-positive curvature. Since the nonpositive curvature condition is …

A Partial Order On The Orthogonal Group, Colum Watt, Thomas Brady

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We define a natural partial order on the orthogonal group and completely describe the intervals in this partial order. The main technical ingredient is that an orthogonal transformation induces a unique orthogonal transformation on each subspace of the orthogonal complement of its fixed subspace.

On Unit Sum Numbers Of Rational Groups, Brendan Goldsmith, Christopher Meehan, S. Wallutis

Articles

The unit sum numbers of rational groups are investigated: the importance of the prime 2 being an automorphism of the rational group is discussed and other results are achieved by considering the number and distribution of rational primes which are, or are not, automorphisms of the group. Proof is given of the existence of rational groups with unit sum numbers greater than 2 but of finite value .

On Torsion And Mixed Minimal Abelian Groups, Brendan Goldsmith, S. O. Hogain

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An abelian group is said to be minimal if it is isomorphic to all its subgroups of finite index. We obtain a complete characterisation of such groups in the torsion case; in the case of mixed groups of rank 1 we obtain a characterisation for some large classes of such groups.

Flow Patterns In A Two-Roll Mill, Christopher Hills

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The two-dimensional flow of a Newtonian fluid in a rectangular box that contains two disjoint, independently-rotating, circular boundaries is studied. The flow field for this two-roll mill is determined numerically using a finite-difference scheme over a Cartesian grid with variable horizontal and vertical spacing to accommodate satisfactorily the circular boundaries. To make the streamfunction numerically determinate we insist that the pressure field is everywhere single-valued. The physical character, streamline topology and transitions of the flow are discussed for a range of geometries, rotation rates and Reynolds numbers in the underlying seven-parameter space. An account of a preliminary experimental study of …

Some Irrational Generalised Moonshine From Orbifolds, Rossen Ivanov, Michael Tuite

Articles

We verify the Generalised Moonshine conjectures for some irrational modular functions for theMonster centralisers related to the Harada-Norton, Held, M12 and L3(3) simple groups based on certain orbifolding constraints. We find explicitly the fixing groups of the hauptmoduls arising in each case.

Bouncing Branes, Emil Prodanov

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Two classical scalar fields are minimally coupled to gravity in the Kachru-Shulz-Silverstein scenario with a rolling fifth radius. A Tolman wormhole solution is found for a R x S^3 brane with Lorentz metric and for a R x AdS_3 brane with positive definite metric.

E-Spatial Technology For Spatial Analysis And Decision Making In Web-Based Land Information Management Systems, James Carswell

Articles

In this paper we describe e-SpatialTM technology, comprising an innovative software solution for deploying integrated web-based spatial applications within Oracle 9i Database environments. The two main components of the solution are the iSMARTTM database development technology and the i-SpatialTM Information Server (iSIS). This technology allows Oracle users to build and deploy both spatially enabled and standard Internet applications without requiring any application-specific GIS source code. It can be deployed on any Oracle supported hardware platform and on any device running a Java Virtual Machine, thus providing full support for wireless, PDAs and other mobile devices. In particular, we describe a …

A Review Of The Different Methods For Assessing Standing Balance, Jacinta Browne, N. J. O'Hare

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This paper is a review of the balance assessment methods currently used to evaluate standing balance. Most of the presently available instrumentation appears to be more suited to research laboratories than to routine clinical situations. Functional assessments of balance appear to be the quickest test to administer and do not require expensive equipment however only gross changes in balance can be detected making them suitable as a screening tool for identifying subject’s needing more thorough evaluation. Force platforms appear to be most suited balance assessment instrumentation to the clinical situation since it produces a real time display and can detect …

The Problem Of A Viscoelastic Cylinder Rolling On A Rigid Half-Space, John Murrough Golden, G.A.C. Graham

Articles

The problem of a viscoelastic cylinder rolling on a rigid base, propelled by a line force acting at its centre, is solved in the noninertial approximation. The method used is based on a decomposition of hereditary integrals developed by the authors in previous work, and on the viscoelastic Kolosov-Muskhelishvili equations which are used to generate a Hilbert problem. In this formulation, the problem reduces to a nonsingular integral equation in space and time, which simplifies under steady-state conditions and for exponential decay materials, to algebraic form. There are also two subsidiary conditions.

In the case of a standard linear model, …

Eddy Structures Induced Within A Wedge By A Honing Circular Arc, C. P. Hills

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In this paper we outline an expeditious numerical procedure to calculate the Stokes flow in a corner due to the rotation of a scraping circular boundary. The method is also applicable to other wedge geometries. We employ a collocation technique utilising a basis of eddy (similarity) functions introduced by Moffatt (1964) that allows us to satisfy automatically the governing equations for the streamfunction and all the boundary conditions on the surface of the wedge. The circular honing problem thereby becomes one-dimensional requiring only the satisfaction of conditions on the circular boundary. The advantage of using the Moffatt eddy functions as …

Eddies Induced In Cylindrical Containers By A Rotating End Wall, Christopher Hills

Articles

The flow generated in a viscous liquid contained in a cylindrical geometry by a rotating end wall is considered. Recent numerical and experimental work has established several distinct phases of the motion when fluid inertia plays a significant role. The current paper, however, establishes the nature of the flow in the thus far neglected low Reynolds number regime. Explicitly, by employing biorthogonality relations appropriate to the current geometry, it is shown that a sequence of exponentially decaying eddies extends outward from the rotating end wall. The cellular structure is a manifestation of the dominance of complex eigensolutions to the homogeneous …

Controlling The Optical Properties Of A Conjugated Co-Polymer Through Variation Of Backbone Isomerism And The Introduction Of Carbon Nanotubes, A. Dalton, J. Coleman, M. In Het Panhuis, B. Mccarthy, A. Drury, W. Blau, J. Nunzi, Hugh Byrne

Articles

The need to control the formation of weakly emitting species in polymers such as aggregates and excimers, which are normally detrimental to device performance, is illustrated for the example of the polymer poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene), using the model compound, 2,5-dioctyloxy-p-distyrylbenzene as a comparison. Two different methods, namely a Homer-Emmons polycondensation in dimethylformamide (DMF) and a Wittig polycondensation in dry toluene, have been used during synthesis resulting in a polymer with a predominantly trans-vinylene backbone and a polymer with a predominantly cis-vinylene backbone, respectively. Photoluminescence and absorption spectroscopy indicate that the polymer forms aggregate species in solution with spectra that are distinctly red-shifted …

Numerical Simulations Of Steady And Pulsed Non-Adiabatic Magnetised Jets From Young Stars, Stephen O'Sullivan, Tom Ray

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No abstract provided.

A Scene Similarity Metric For Matching Configurations Of Image Objects, James Carswell

Articles

This paper proposes a novel solution to querying image databases by matching raster features to imagery completely in the raster/spatial domain using the shape of single features together with their spatial relations as the matching primitives. The core feature-based matching module combines a revised least-squares matching algorithm, to accomplish the matching process on binary images, with a unique implementation of a feature library that organizes and links query objects with their images in the database, thus enabling fast and efficient real-time retrieval of relevant imagery. The purpose is to extend this previous work of ours, which matches on the shape …