Recent studies of queries submitted to Internet Search Engines have shown that non-English queries and unclassifiable queries have nearly tripled during the last decade. Most search engines were originally engineered for English. They do not take full account of inflectional semantics nor, for example, diacritics or the use of capitals which is a common feature in languages other than English. The literature concludes that searching using non-English and non-Latin based queries results in lower success and requires additional user effort to achieve acceptable precision. The primary aim of this research study is to develop an evaluation methodology for identifying the shortcomings and measuring the effectiveness of search engines with non-English queries. It also proposes a number of solutions for the existing situation. A Greek query log is analyzed considering the morphological features of the Greek language. Also a text extraction experiment revealed some problems related to the encoding and the morphological and grammatical differences among semantically equivalent Greek terms. A first stopword list for Greek based on a domain independent collection has been produced and its application in Web searching has been studied. The effect of lemmatization of query terms and the factors influencing text based image retrieval in Greek are also studied. Finally, an instructional strategy is presented for teaching non-English students how to effectively utilize search engines. The evaluation of the capabilities of the search engines showed that international and nationwide search engines ignore most of the linguistic idiosyncrasies of Greek and other complex European languages. There is a lack of freely available non-English resources to work with (test corpus, linguistic resources, etc). The research showed that the application of standard IR techniques, such as stopword removal, stemming, lemmatization and query expansion, in Greek Web searching increases precision. ii

The increasingly ubiquitous nature of software development has presented new challenges to usability research, thereby introducing a need for investigation of the use of field evaluation methods. This thesis explores the application of field methods to usability evaluation, in order to understand the challenges involved in applying such methods and the contextual issues surrounding their implementation. More specifically, the research aims to investigate the relationship between context and design when using field evaluation studies. This work is especially important because it represents a first step towards systemising HCI field evaluation methodologies. A case study approach was taken in order to provide real-world examples of field method usage, and in addition two exploratory studies were conducted in order to explore methodological challenges. This process resulted in the development of a systematic field evaluation method named Rapid Contextual Evaluation. In providing a rapid approach to field evaluation, this thesis addresses the recent gaps in the literature regarding the recent lack of publication of systematic evaluation methods and the lack of detailed methodological case studies to inform practice. The work reported here is the first to present such case studies, and the first to describe in detail the application of a systematic field evaluation method in a real world context. The research identified the major challenges experienced in implementing field evaluation studies, and proposed methodological changes to address these. The relationship between context and design was discovered to be iterative, and field evaluation approaches were found to identify a broad range of contextual issues which went beyond system interaction. In conclusion, the thesis identifies areas where future research efforts should focus in order to deliver the most valuable improvements to field evaluation methods.

Abstract The contribution of the volatile constituents to the overall antimicrobial efficacy of the medicinal plant Tarchonanthus camphoratus was considered, where different extraction techniques were applied to yield four fractions. These comprised of the essential oil prepared by hydrodistillation, non-volatile constituents prepared by extraction of plant material remaining in the distilling apparatus (having no or negligible volatile constituents), and extracts prepared from fresh and dried plant material having both volatile and non-volatile constituents. The antimicrobial activities of the non-volatile and volatile fractions of T. camphoratus singularly (MIC method) and in combination (isobologram ratio method) demonstrated that the volatile constituents play an integral role in the total antimicrobial efficacy of the plant. The MIC values for the essential oils of T. camphoratus ranged from 1.5 to 16.0 mg/ml depending on the pathogen studied. With the exception of studies on Klebsiella pneumoniae, the non-volatile fraction devoid of volatile constituents displayed higher antimicrobial efficacies (2.0–4.0 mg/ml). When the volatile and non-volatile fractions were combined, increased efficacy was mostly noted with the dried plant material mostly showing a higher antimicrobially-active profile. Synergistic interactions were further validated by the isobologram studies on the combination of non-volatiles with essential oil.

My work attempts to enrich physical place through the creation of virtual layers that enable users to understand their contexts more meaningfully. The intention is to address the practices of spatial and information design as the same design problem, thus acknowledging the simultaneity of contemporary lifestyles. This report summarizes my explorations in graduate school to develop a methodology, which combines the use of physical and virtual components to enable the design of meaningful places. / text

published_or_final_version / Psychology / Doctoral / Doctor of Philosophy

published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

No description available.

Two experiments comparing user performance on ClearType and Regular displays are reported. In the first, 26 participants scanned a series of spreadsheets for target information. Speed of performance was significantly faster with ClearType. In the second experiment, 25 users read two articles for meaning. Reading speed was significantly faster for ClearType. In both experiments no differences in accuracy of performance or visual fatigue scores were observed. The data also reveal substantial individual differences in performance suggesting ClearType may not be universally beneficial to information workers.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. (1992) Reading from paper versus screens: a critical review of the empirical literature. Ergonomics, 35(10), 1297-1326. Abstract: The advent of widespread computer use in general and increasing developments in the domain of hypertext in particular have increased awareness of the issue of reading electronic text. To date the literature has been dominated by reference to work on overcoming speed deficits resulting from poor image quality but an emerging literature reveals a more complex set of variables at work. The present review considers the differences between the media in terms of outcomes and processes of reading and concludes that single variable explanations are insufficient to capture the range of issues involved in reading from screens.

This is a preprint of a paper published (with a slightly different title: Spatial semantics and individual differences in the perception of shape in information space) in the Journal of the American Society for Information Science, 51(6), 521-528. Abstract: User problems with large information spaces multiply in complexity when we enter the digital domain. Virtual information environments can offer 3-D representations, reconfigurations and access to large databases that can overwhelm many usersâ abilities to filter and represent. As a result, users frequently experience disorientation in navigating large digital spaces to locate and use information. To date, the research response has been predominantly based on the analysis of visual navigational aids that might support users' bottom-up processing of the spatial display. In the present paper an emerging alternative is considered that places greater emphasis on the top-down application of semantic knowledge by the user gleaned from their experiences within the socio-cognitive context of information production and consumption. A distinction between spatial and semantic cues is introduced and existing empirical data are reviewed that highlight the differential reliance on spatial or semantic information as domain expertise of the user increases. The conclusion is reached that interfaces for shaping information should be built on an increasing analysis of users' semantic processing.