A Numerical Approach to the Accurate Calculation of Atomic and Molecular Properties

An attempt is made to demonstrate that simple numerical methods can be used to advantage in the accurate calculation of atomic and molecular properties. In the early part of the thesis finite-difference techniques are employed in conjunction with conventional variational methods to calculate accurately the correlation energies of small atoms within a variety of perturbation schemes. Of particular interest is a thorough investigation of Hartree-Fock perturbation theory through third order for the Be isoeleotronic sequence Li- -- Ne6+ with about a 90% recovery of Ecorr. Numerical methods are also used to examine the efficacy of the single-centre approach to the calculation of the electronic structures of simple molecules in their ground and excited states, the high accuracy of the computational scheme employed allowing some insight into the frequently observed slow convergence of the one-centre method. The efficiency of numerical techniques in the determination of atomic and molecular properties is further shown by studies on the non-empirical evaluation of atomic polarisabilities (static and dynamic) and of interatomic dispersion forces. Notably a new method of computing Van der Waals coefficients of considerable elegance and economy is presented. In the final section of the work the numerical computational techniques developed in non-empirical calculations of pair correlation energies, polarisabilities, dispersion coefficients in small systems are applied to much larger atoms within a model potential framework. All of the above properties are determined for a wide variety of systems with however the alkali metals and their anions being the subject of the most comprehensive treatment

Delivering job search services in rural labour markets: the role of ICT

This paper reports original research on job seekers in two contrasting rural areas in Scotland: one a remote rural area; the other semi-rural with strong metropolitan connectivity. It seeks to answer two key questions. Firstly, what are the potential benefits and barriers associated with the delivery of services for rural job seekers through the use of Information and Communications Technology (ICT)-based systems? And following from this, what is the nature and extent of the 'digital divide' affecting unemployed job seekers and what policies are required to address this problem? Rural labour markets in the United Kingdom, like those across Europe, have recently experienced a period of continuous and rapid change. The decline of primary sector industries has been accompanied by increases in service employment, especially in tourism. However, in the UK, as elsewhere, this economic transition has not been without its difficulties. Whilst social exclusion is less prevalent in rural areas than in many cities, instances f poverty remain. Unemployment, and particularly long-term unemployment, has been cited as an important factor explaining the continuing problem of social exclusion in many rural areas. Recent research has suggested that an important barrier to work faced by unemployed people in rural areas relates to the absence of locally-based job search and advice services. The Employment Service (the main public agency in the UK dealing with job seekers) has argued thagiven the remote and sparsely populated nature of many rural labour markets, ICT-based job search and advice services (e.g. delivered through telephone helplines and the Internet) may offer the most efficient and cost-effective policy solution in many areas. However, the viability of this policy is dependent on the level of ICT awareness and access among job seekers. Interviews were conducted with over 400 job seekers in the two areas. The Caithness and Sutherland area in northern Scotland is among the most remote and least densely populated in Europe, with unemployment rates well above the national average. West Lothian, in contrast, is situated near to Scotland's economic centre and is a major centre of manufacturing activity with unemployment below the national average. The interviws examined the level of ICT skills possessed, attitudes towards and access to ICT, and additionally collected information on a range of personal skills and attitudes. Evidence of relatively low levels of ICT awareness and access was found in both communities Although those residing in the more remote study area were also more likely to have Internet access, a significant minority did not even have access to a telephone at home. The paper concludes that, if ICT is to prove to be the waforward in delivering services for job seekers in rural areas, community-based access and support facilities must be provided, along with appropriate training for job seekers in basic and higher level ICT skills.

Enabling rural broadband via TV "white space"

The use of multiple frequency bands within a wireless network allows the advantages of each band to be exploited. In this paper we discuss how HopScotch, a rural wireless broadband access test bed running in the Scottish Highlands and Islands, uses both 5 GHz and ultra high frequency "white space" bands to offer large data rates and expansive coverage whilst reducing the number of base stations or required transmission power. This reduction in energy consumption allows HopScotch to provide a low-cost and green solution for rural broadband delivery

"WindFi" - a renewable powered base station for rural broadband

The HopScotch rural wireless broadband access test bed uses a network of low power base stations, powered by renewable energy sources to provide a low-cost rural broadband solution. In this paper we discuss the low power design aspects of the HopScotch base station and the impact on the required generation potential of renewable sources, battery bank sizing and the use of tracking PV arrays

Developing numerical libraries in Java

The rapid and widespread adoption of Java has created a demand for reliable and reusable mathematical software components to support the growing number of compute-intensive applications now under development, particularly in science and engineering. In this paper we address practical issues of the Java language and environment which have an effect on numerical library design and development. Benchmarks which illustrate the current levels of performance of key numerical kernels on a variety of Java platforms are presented. Finally, a strategy for the development of a fundamental numerical toolkit for Java is proposed and its current status is described.Comment: 11 pages. Revised version of paper presented to the 1998 ACM Conference on Java for High Performance Network Computing. To appear in Concurrency: Practice and Experienc

A Parameterization of the Microphysical Processes Forming Many Types of Winter Precipitation

Several types of precipitation, such as freezing rain, ice pellets, and wet snow, are commonly observed during winter storms. The objective of this study is to better understand the formation of these winter precipitation types. To address this issue, detailed melting and refreezing of precipitation was added onto an existing bulk microphysics scheme. These modifications allow the formation of mixed-phase particles and these particles in turn lead to, or affect, the formation of many of the other types of precipitation. The precipitation type characteristics, such as the mass content, liquid fraction, and threshold diameters formed during a storm over St John’s, Newfoundland, Canada, are studied and compared with observations. Many of these features were reproduced by the model. Sensitivity experiments with the model were carried out to examine the dependence of precipitation characteristics in this event on thresholds of particle evolution in the new parameterization

Extratropical Cyclones and Precipitation within the Canadian Archipelago during the Cold Season

Extratropical cyclones produce much of the precipitation over the Arctic, but the details of this cause-effect relationship are not well documented. In this study, we examined extratropical cyclones within the Canadian Archipelago, a subregion of the Arctic, over the period 1948– 97. Using data from the Historical Canadian Climate Data (HCCD), the U.S. National Climate Center (UNCC), and the European Meteorological Bulletin (EMB), we assessed the relationship between extratropical cyclones and cold-season snowfall (October–April) for 10 events at each of 11 surface stations within the region. These events were relatively brief (72 h or less), but resulted in precipitation totals that exceeded the average monthly amount. At each station, within the 10 most extreme precipitation months of the 50-year study period, we often found a single event that accounted for approximately one-third of the total snowfall in that month. For sites located in the southeastern Archipelago, eventrelated storms typically approached from the southeast, whereas southwestern sites were affected by southwesterly storms, and northwestern sites, by northwesterly storms. In many cases, cyclone dissipation occurred within 24 h of the event’s conclusion. Precipitation analyses in this study were considerably affected by snowfall undercatchment; the magnitude of this effect needs further examination in future studies. However, the identification of extreme events and related storm tracks appears to be relatively unaffected by the lack of corrected precipitation data.Les cyclones extratropicaux sont responsables d’une grande partie des précipitations dans l’Arctique, mais les détails de cette relation de cause à effet ne sont pas bien documentés. Nous nous penchons, dans cette étude, sur les cyclones extratropicaux au sein de l’archipel Canadien, une sous-région de l’Arctique, au cours de la période allant de 1948 à 1997. À l’aide de données tirées de la Base de données climatiques historiques du Canada (HCCD), du National Climate Center (UNCC) américain et du Bulletin Météorologique Européen (BME), on a évalué la relation entre les cyclones extratropicaux et les chutes de neige en saison froide (d’octobre à avril) pour 10 événements s’étant produits à chacune de 11 stations de surface dans la région. Ces événements avaient une durée relativement courte (72 h ou moins), mais ils provoquaient des précipitations totalisant plus que la moyenne mensuelle. À chaque station, au cours des 10 mois de précipitations les plus intenses sur les 50 ans de la période d’étude, on a souvent trouvé un seul événement qui comptait pour environ un tiers du total de l’apport neigeux pour ce mois. Pour les emplacements situés dans la partie sud-est de l’archipel, les tempêtes reliées aux événements venaient d’ordinaire du sud-est, tandis que ceux du sud-ouest étaient touchés par les tempêtes dues aux vents du sud-ouest, et ceux du nord-ouest, par les tempêtes dues aux vents du nord-ouest. Dans bien des cas, le cyclone se dissipait dans les 24 h suivant la fin du phénomène. Dans cette étude, les analyses de précipitations étaient considérablement influencées par une sous-estimation de l’apport neigeux; il faudrait étudier plus à fond l’importance de cet effet dans des recherches ultérieures. L’identification d’événements extrêmes et des trajectoires de tempêtes qui y sont associées semble relativement insensible au manque de données hyétométriques rectifiées

Similarity of Prosody Between Speech and Singing: A Methodological Study

Background: People with neurogenic communication disorders such as Parkinson’s Disease and Aphasia have language and speech abilities that are characterized by disturbances in speech prosody: abnormal variations of the intonation, stress, and duration of speech. Singing has been used as a therapeutic approach to help regulate and normalize prosody; however, little is known about how to best use the prosody of singing to meet the speech needs of different neuro pathologies. Objectives: The purpose of this study was to identify how the spoken and musical prosody of simple songs compare on measures of intensity, intonation, and duration as well as establish a method of assessing a song’s efficacy in speech therapy. Methods: An observational study compared the recordings of two singers and two speakers (4 participants total) who sang or read aloud the lyrics of three simple songs: “Row, Row, Row Your Boat”, “Happy Birthday To You”, and “Twinkle, Twinkle Little Star”. Participants were asked to either sing or read aloud each selection three times. Analysis: The acoustic analyses of the recordings were performed using the software Praat and were assessed for the prosodic measures of intonation by the fundamental frequency contour (semitones), intensity by the decibel (dB) contour, and rhythm by syllabic duration (seconds). Results: Comparing the prosodic differences between sung and spoken lyrics, on average the highest similarity between speech and singing occurred for the measure of duration (SCP Row = 92%, SCP Twinkle = 85%, SCP Happy = 83)%, second highest similarity for intensity (SCP Row =65%, SCP Twinkle =56%, SCP Happy =54% ), and the least highest similarity of intonation (SCP Row = 69%, SCP Twinkle = 49% , SCP Happy = 42%). Out of the selections Row, Row, Row Your Boat was most speech like while Happy Birthday to you was least speech like. Conclusions: This methodological study for speech and singing helped to establish a basis for assessing how simple songs can be utilized as a tool in speech therapy