bluuebunny/crossref_metadata_2025 huggingface dataset:
Aesthetics in Data Visualization
Authors: Jung Heekyoung , Kim Tanyoung , Yang Yang , Carli Luis , Carnesecchi Marco , Rizzo Antonio , Gurrin Cathal
Published: July 2013

Data visualization has been one of the major interests among interaction designers thanks to the recent advances of visualization authoring tools. Using such tools including programming languages with Graphics APIs, websites with chart topologies, and open source libraries and component models, interaction designers can more effectively create data visualization harnessing their prototyping skills and aesthetic sensibility. However, there still exist technical and methodological challenges for interaction designers in jumping into the scene. In this article, the authors introduce five case studies of data visualization that highlight different design aspects and issues of the visualization process. The authors also discuss the new roles of designers in this interdisciplinary field and the ways of utilizing, as well as enhancing, visualization tools for the better support of designers.
Understanding Spatial and Non-spatial Cues in Representing Categorical Information
Authors: Yatid Moonyati , Takatsuka Masahiro
Published: July 2013

The continuously increasing amount of digital information available to computer users has led to the wide use of notification systems. Although these systems could support the management of information, they could also be an interruption to primary work. To minimize this interruption, a number of approaches, which notify the different categorical information, have been introduced. In this work, we focused on understanding the effectiveness of different types of visual cues to effectively represent categorical notification. Five basic visual parameters of motion, colour, shape, motion and spatial were chosen to represent sets of two categories, four categories, six categories and eight categories of information. The effectiveness of these visual cues in assisting users’ ability to decode the categorical cues was examined through a series of experimental studies. Findings suggest the superiority of using colour, shape, and spatial cues to represent categorical information. Post experiment questionnaire reveals possible reasons for their efficiency. Spatial memory supports spatial cues while linguistic influence supports the shape/colour cues. The unsuitability of size parameter is possibly due to not being able to measure the cues against something during the encoding process. This makes it difficult to determine how each cue differs from the rest of the cues in the parameter, especially when number of categories increase. As for the motion parameter, encoding the cues took far longer response times, although time taken is consistent across number of categories. The different effects of these basic visual cues suggest the importance of careful design selection to ensure successful visualization.
Feature-Based Uncertainty Visualization
Authors: Wu Keqin , Zhang Song
Published: July 2013

While uncertainty in scientific data attracts an increasing research interest in the visualization community, two critical issues remain insufficiently studied: (1) visualizing the impact of the uncertainty of a data set on its features and (2) interactively exploring 3D or large 2D data sets with uncertainties. In this chapter, a suite of feature-based techniques is developed to address these issues. First, an interactive visualization tool for exploring scalar data with data-level, contour-level, and topology-level uncertainties is developed. Second, a framework of visualizing feature-level uncertainty is proposed to study the uncertain feature deviations in both scalar and vector data sets. With quantified representation and interactive capability, the proposed feature-based visualizations provide new insights into the uncertainties of both data and their features which otherwise would remain unknown with the visualization of only data uncertainties.
Cognitive Processes and Traits Related to Graphic Comprehension
Authors: Zoss Angela M.
Published: July 2013

The subject of how visualizations and graphics in general can be understood by their viewers draws on theories from many fields of research. Such theories might address the formal structure of the visualization, the style and graphic design skills of the creator, the task driving the viewer’s interaction with the visualization, the type of data being represented, or the skills and experiences of viewer. This chapter focuses on this last question and presents a set of interrelated constructs and viewer traits that contribute to (or interfere with) a viewer’s ability to analyze a particular data visualization. The review covers spatial thinking skills, cognitive styles, mental models, and cognitive load in its discussion of theoretical constructs related to graphic comprehension. The review also addresses how these cognitive processes vary by age, sex, and disciplinary background–the most common demographic characteristics studied in relation to graphic comprehension. Together, the constructs and traits contribute to a diverse and nuanced understanding of the viewers of data visualizations.
Articulate
Authors: Sun Yiwen , Leigh Jason , Johnson Andrew , Di Eugenio Barbara
Published: July 2013

This chapter presents an approach to enable non-visualization experts to craft advanced visualizations through the use of natural language as the primary interface. The main challenge in this research is in determining how to translate imprecise verbal queries into effective visualizations. To demonstrate the viability of the concept, the authors developed and evaluated a prototype, Articulate, which allows users to simply ask the computer for questions about their data and have it automatically generate visualizations that answer these questions. The authors discovered that by relieving the user of the burden of learning how to use a complex interface, they enable them to focus on articulating better scientific questions and wasting less time in producing unintended visualizations.
A Framework for Developing Diagram Applications
Authors: Lai Wei , Huang Weidong
Published: July 2013

This chapter presents a framework for developing diagram applications. The diagrams refer to those graphs where nodes vary in shape and size used in real world applications, such as flowcharts, UML diagrams, and E-R diagrams. The framework is based on a model the authors developed for diagrams. The model is robust for diagrams and it can represent a wide variety of applications and support the development of powerful application-specific functions. The framework based on this model supports the development of automatic layout techniques for diagrams and the development of the linkage between the graph structure and applications. Automatic layout for diagrams is demonstrated and two case studies for diagram applications are presented.
Towards Healthy Public Policy
Authors: Yang Julie
Published: July 2013

As an issue that affects a significant portion of the Canadian population, food security must be addressed in public health policy and research. Decision-making for food security is a complex task that needs to take into account a diverse range of issues including production, processing, distribution, access, consumption, and waste management. This approach to policymaking for food security, known as food systems analysis, makes use of a large amount of geospatial data. Public health informatics can offer some potential answers to handling and using this large amount of information. The purpose of this chapter is to provide a brief introduction to Geographic Information Systems (GIS) and how they are used in public health, particularly for food systems analysis. A hypothetical scenario that envisions using a type of spatial analytic tool, called Spatial On-Line Analytic Processing (Spatial OLAP or SOLAP), for public health decision-making is also introduced. In describing both GIS and spatial OLAP, a case for incorporating food systems analysis into public health practices is made.
How Web 2.0 Shapes Patient Knowledge Sharing
Authors: Libreri Chiara , Graffigna Guendalina
Published: July 2013

Web 2.0 has totally changed the health communication world. In particular, it has reconfigured peer exchanges about health. These exchanges are important because they allow knowledge sharing and construction between patients, in particular chronic patients. Although their importance is well established, this field of study brings together a variety of theories not uniformly shared or understood. It is not clear how patients use Web for knowledge processes: what kind of knowledge processes happen in Web 2.0 between patients? How does Web 2.0 sustain or impede these processes? The aim of this research is to map virtual exchanges about diabetes in Italy by developing a systematic exploration of Web using the main search engines (Google, Yahoo) and analyzing the site that hosts posts and exchanges about diabetes. According to a psychosocial perspective, findings highlight the main features of online knowledge processes among patients.
Communities of Communication
Authors: Rogers Laurie Stone
Published: July 2013

This chapter discusses the potential of social media use as an access to interpersonal relationships for teachers. Society has been forever altered by the shifts in the intellectual landscapes of learning and knowing through the Internet. By utilizing mobile communication technologies, Internet pathways allow growth in personal and professional relationships in real time, providing opportunity for open and profound dialogues, learning, and global perspectives. Yet even with the strong social presence of Internet communications in today’s society, our teachers continue to struggle with building interpersonal relationships with colleagues. Drawing from the literature as well as from personal experiences and relationships, this chapter explores some of the interpersonal challenges teachers face at work due to physical and abstract barriers, as well as the possible solution found in social media. This perspective hopefully adds to understanding regarding the interpersonal challenges teachers may experience at work, the importance of meeting those challenges, and the potential inter-relational benefits resulting from social media use.
Does Mobile Technology Have a Place in Differentiated Instruction?
Authors: Cumming Therese M.
Published: July 2013

Although mobile technologies are relatively new, they have quickly become ubiquitous in education, despite a limited evidence base for their efficacy in instructional design. This chapter discusses differentiated instruction for the inclusive classroom and how this can be best accomplished using mobile technology as an educational tool. Using mobile computing devices such as the iPad in differentiated instruction has many advantages, but is not without challenges. Many of these challenges can be addressed using suggestions from previous research in the areas of differentiated instruction and educational technology. Future research is necessary to provide a solid evidence-base supporting the use of mobile technology with diverse learners in all levels of classroom instruction.
Mobile Technology and Differentiated Learning
Authors: Orr Ann C. , Conley John F.
Published: July 2013

As the world falls in love with the iPad and other touch screen tablet technologies, no one is more excited by the possibilities than those of us who teach students with significant disabilities. The mobile tablet’s intuitive interface, variety of accessibility options, and almost limitless possibilities for individualized intervention make this technology a true game-changer for children and adults with special needs. This chapter explores the landscape of tablet use to increase the education, communication, and independence of students with moderate to severe disabilities. Current research on effective teaching and learning practice that can best be employed through mobile touch screen technologies is presented.
A Multiple-Case Study Examining Teachers’ Use of iPod Touches in Their Pedagogical Practices for English Language Learners
Authors: Liu M. , Navarrete C. , Maradiegue E. , Wivagg J.
Published: July 2013

Mobile technology has been noted as a valuable resource for students in K-12 education and potentially for English Language Learners (ELL). ELL students enter schools with different levels of English proficiency and teaching such a population often presents a daunting academic challenge. Using mobile devices for learning, holds certain potentials as the literature indicates. Benefits of mobile technology such as flexibility, accessibility, interactivity, and motivation and engagement have been documented. This multiple-case study examines ELL teachers’ use of the iPod touch in their instruction at elementary, middle, and high school levels to understand how such mobile devices are used and the teachers’ perception of using them.
An ROI Ed-Biz Approach for Deploying Mobile Pedagogy
Authors: McConatha Douglas
Published: July 2013

The long history and short past of online distance education is posited as a precursor to the monumental changes revolutionizing global educational activity. The author argues for the use of Mobile Pedagogy as an idiom for the inclusive nature of the platforms, processes, teaching methodologies, and infrastructures (technical and instructional) that comprise this new approach in the world of learning. As such, this chapter discusses the critical element of finances by looking at contemporary learning theory and a specific E-learning system model termed CADRE (Content, Access, Distribution, Revenue, and Evaluation). To help delineate connections between elements in this emerging ecosystem the important component of cost is used as exemplar. As the cost of Higher Education rises, answers to questions long been taken for granted have come to the forefront of the concern for parents and students: Is College worth the cost? Are expensive elite schools a guarantee to entry into the world of work? Are the opportunity costs for a four year (or more) degree program worth the investment? These questions are examined in the context of an ROI (Return on Investment) conjecture that assumes benefits must outweigh costs in order to be worthwhile. In the era of Open Courseware, free courses, MOOCs (Massive Open Online Courses), and teaching and learning anytime, anywhere by anybody the issues of cost, quality, sustainability and evaluation are addressed within the context of an educational-business (Ed-Biz) framework. Various strategies relating to the kinds of monetization that could support these directions are offered.
A Proposal to Study of Cross Language Information Retrieval (CLIR) System Users’ Information Seeking Behavior
Authors: Ha YooJin
Published: July 2013

There has been an enormous increase for information written in different languages by users from various backgrounds and disciplines. This chapter proposes a research design to examine multilingual information users’ information behaviors when using a Cross Language Information Retrieval (CLIR) system. Development of a true CLIR is absolutely necessary so that the system would allow users to access information written in the user’s languages of choice. Kuhlthau’s Information Search Process (ISP) model was borrowed as a theoretical framework. Of particular concern are those users who want information represented by a language different than the users’ original query or for those users who would like to retrieve additional information written in a second and/or third language or in a language which cannot be understood by them. This research is expected to yield a revised or new ISP model applicable to CLIR environments. It is expected that this study will also increase our understanding of CLIR users. The expected CLIR users include many of non-English speakers, especially users in developing countries who need this kind of CLIR system due to lack of materials in their own language. It is possible that the results of this research could inform CLIR system designers. The chapter is composed of purpose of study, literature review, theory, research questions, methodology, and discussion section. In the literature review section, pertinent research studies from information seeking behavior, cross language information retrieval, and general relevance studies are presented. Kuhlthau’s ISP model is introduced in detail in the theory section. A possible application of Kuhlthau’s ISP Model to the CLIR environment is presented in a table format. Research questions are developed from the literature reviews and Kuhlthau’s model. Each research question, premises/assumptions, and its correspondent methodology are proposed in the methodology section. Limitations are discussed in the discussion section.
Where Do Mongolian Scholars Go?
Authors: Scheiding Thomas , Yadamsuren Borchuluun , Lkhagva Gantulga
Published: July 2013

In developing countries, one of the many challenges faced by researchers is increased pressure to conduct research, but inadequate resources provided to do their work. Perhaps nowhere is the inadequacy of research resources more apparent than in the area of access to scholarly research. In this chapter, using survey data, usage statistics, and interviews of researchers, librarians, and research administrators, we describe the information seeking behavior of scholars in Mongolia and how this behavior intersects with the resources made available by research administrators and librarians. Much of the existing research on scholarly communication in developing countries has focused on whether access to scholars should be donated or provided free of charge without restriction. In Mongolia, the issue isn’t so much whether access to scholarly communication should be donated or not, but rather whether the scholarly communication system meets researcher needs, is adapted to constraints within the country, and reduces communication dependency. What we find is that the scholarly communication system in Mongolia fails to completely meet researcher needs and makes the country dependent on the scholarly communication products provided by outsiders.
Contextual Factors Influencing Information Seeking Behavior of Social Scientists
Authors: Al-Suqri Mohammed Nasser
Published: July 2013

Many researchers in the area of information seeking behavior have highlighted the importance of context in influencing information-seeking behavior. However, few have elaborated on how contextual factors influence information-seeking in practice. This chapter explores the impact of disciplinary traditions of non-western, developing country external environments on patterns of information seeking and retrieval. Conditions that influence information seeking behaviors of social science scholars in non-western, developing countries impact research traditions, publication patterns, and subsequent formats are examined. This chapter draws on existing literature to examine the impact of contextual factors on information seeking by social science scholars as well as, on relevant findings based on research with other categories of researchers. The chapter concludes that there is substantial evidence from previous research to indicate the importance of contextual factors in influencing the information-seeking behavior of social scientists. Some of these factors are related to the nature of social science as a domain of study, while others are related to researcher’s external environment, including constraints on the availability of particular types of information.
Augmentative and Alternative Communication Systems for the Motor Disabled
Authors: Pino Alexandros
Published: July 2013

This chapter discusses Augmentative and Alternative Communication (AAC) for individuals with motor disabilities. Motor disabilities do not only affect movement, but very often also affect speech. In these cases where voice is very weak, speech is unintelligible, or motor problems in the human speech production systems do not allow a person to speak, AAC is introduced. Aided and unaided communication is explained, and low and high tech AAC examples are illustrated. The ITHACA framework for building AAC applications is used as a paradigm in order to highlight the AAC software lifecycle. The same framework is also used to highlight AAC software design issues concerning component-based development (the open source model and the Design for All principles). Key features of an AAC application like virtual keyboards, scanning techniques, symbol dashboards, symbolic communication systems, message editors, symbol translation, word prediction, text to speech, and remote communication are presented. Finally, practical hints for choosing an AAC system are given and a case study of informally evaluating it is cited.
Indoor Navigation and Location-Based Services for Persons with Motor Limitations
Authors: Riga Paraskevi , Kouroupetroglou Georgios
Published: July 2013

Persons with motor limitations constitute a group-challenge when building indoor navigation and Location-Based Services (LBS). The authors present here the systematic approach they have developed that has to be taken into account in the user needs analysis of persons with motor disabilities when an advanced system for indoor navigation and LBS is designed. In the first part the authors present a step-by-step and detailed methodology about the extraction of the user requirements’ knowledge in order to develop an indoor navigation and LBS system that provides adequate and usable output to persons with motor limitations. In the second part, after an overview of the existing indoor LBS, the authors present the development of the MNISIKLIS system giving emphasis on the User Interface designed after following the knowledge derived from the first part.
Assistive Technologies and Autism Spectrum Disorders
Authors: Alcantud Francisco , Alonso Yurena , Coret Javier , Jiménez Esteban
Published: July 2013

This chapter discusses assistive technologies applied in people with autism spectrum disorders and how these technologies promote their adaptation. We analyzed different technological application areas such as detection, assessment, diagnosis, intervention, training, learning, environment control, communication, mobility, and access. In recent years there has been a notable increase of publications and works related to the use of assistive technologies applied to Autism Spectrum Disorders. While most of the publications present novel systems, devices, and applications (smartphones, tablets, robots, avatars, etc.), general evaluation of the results is insufficient. Future lines of research are targeted to realize intelligent environments in order to integrate all knowledge and technological developments made in recent years.
Structural Dynamics Analysis of Rotating Blades Using Fully Intrinsic Equations, Part II: Dual-Load-Path Configurations
Authors: Sotoudeh Zahra , Hodges Dewey H.
Published: July 2013

As part of an ongoing investigation into potential advantages of so-called fully intrinsic formulations, this paper presents an application of the fully intrinsic equations of motion and kinematics for beams to rotor blades. A fully intrinsic formulation is devoid of displacement and
rotation variables. Although the governing equations are geometrically exact, they are free of the attendant singularities and infinite-degree nonlinearities found in other types of formulations. These nonlinear, first-order partial differential equations are suitable for analyzing initially
curved and twisted, anisotropic beams and thus are very attractive for analysis of both helicopter and wind turbine blades. This two-part paper is devoted to the structural dynamics modeling of rotor blades with a wide variety of boundary conditions—in particular hingeless and bearingless
rotor configurations. Part II is devoted to verification of certain dual-load-path configurations suggested by Bell Helicopter Textron.
The intra-host evolutionary and population dynamics of human immunodeficiency virus type 1: a phylogenetic perspective
Authors: Salemi Marco
Published: July 2013

The intra-host evolutionary and population dynamics of the human immunodeficiency virus type 1 (HIV-1), the cause of the acquired immunodeficiency syndrome, have been the focus of one of the most extensive study efforts in the field of molecular evolution over the past three decades. As HIV-1 is among the fastest mutating organisms known, viral sequence data sampled over time from infected patients can provide, through phylogenetic analysis, significant insights about the tempo and mode of evolutionary processes shaped by complex interaction with the host milieu. Five main aspects are discussed: the patterns of HIV-1 intra-host diversity and divergence over time in relation to different phases of disease progression; the impact of selection on the temporal structure of HIV-1 intra-host genealogies inferred from longitudinally sampled viral sequences; HIV-1 intra-host sub-population structure; the potential relationship between viral evolutionary rate and disease progression and the central evolutionary role played by recombination occurring in super-infected cells.
Current trends of HIV recombination worldwide
Authors: Lau Katherine A. , Wong Justin J.L.
Published: July 2013

One of the major characteristics of HIV-1 is its high genetic variability and extensive heterogeneity. This characteristic is due to its molecular traits, which in turn allows it to vary, recombine, and diversify at a high frequency. As such, it generates complex molecular forms, termed recombinants, which evade the human immune system and so survive. There is no sequence constraint to the recombination pattern as it appears to occur at inter-group (between groups M and O), as well as inter- and intra-subtype within group M. Rapid emergence and active global transmission of HIV-1 recombinants, known as circulating recombinant forms (CRFs) and unique recombinant forms (URFs), requires urgent attention. To date, 55 CRFs have been reported around the world. The first CRF01_AE originated from Central Africa but spread widely in Asia. The most recent CRF; CRF55_01B is a recombinant form of CRF01_AE and subtype B, although its origin is yet to be publicly disclosed. HIV-1 recombination is an ongoing event and plays an indispensable role in HIV epidemics in different regions. Africa, Asia and South America are identified as recombination hot-spots. They are affected by continual emergence and co-circulation of newly emerging CRFs and URFs, which are now responsible for almost 20% of HIV-1 infections worldwide. Better understanding of recombinants is necessary to determine their biological and molecular attributes.
Guidelines for phytosociological classifications and descriptions of vegetation in southern Africa
Authors: Brown Leslie R. , Du Preez Pieter J. , Bezuidenhout Hugo , Bredenkamp George J. , Mostert Theo H.C. , Collins Nacelle B.
Published: July 2013

Changes in the environment are first observed in changes in the vegetation. Vegetation survey, classification and mapping form the basis on which informed and scientifically defendable decisions on the environment can be taken. The classification and mapping of vegetation is one of the most widely used tools for interpreting complex ecosystems. By identifying different plant communities we are essentially identifying different ecosystems at a particular hierarchical level. Phytosociologists in Europe have been involved in such studies following, in particular, the Braun-Blanquet approach since the early 1900s. In South Africa, such studies were undertaken on a limited basis from the early 1970s and have since then steadily increased. The surveying of the enormous diversity of South African vegetation is one of the objectives of phytosociological studies. The demand for such data has steadily increased over the past few years to guide conservation policies, biodiversity studies and ecosystem management. In South Africa, numerous publications on the vegetation of conservation and other areas in the different biomes have been produced over the last few decades. However, vegetation scientists in South Africa experience unique problems. The purpose of this article is therefore to provide an overview of the history and the specific focus of phytosociological studies in South Africa and to recommend minimum requirements and methods to be followed when conducting such studies. It is believed that the incorporation of these requirements will result in scientifically justifiable research of high quality by phytosociologists in South Africa.Conservation implications: Effective conservation cannot be obtained without a thorough knowledge of the ecosystems present in an area. Consistent vegetation classifications and descriptions form the basis of conservation and monitoring exercises to maintain biodiversity. The incorporation of these guidelines and requirements will facilitate quality phytosociological research in South Africa.
In vitro antimikrobiese aktiwiteit en in vitro-toksisiteit van die afbraakprodukte van trimetoprim
Authors: Bergh J. J. , Breytenbach J. C. , Van Dyk S.
Published: July 2013

The in vitro antimicrobial activity and in vitro toxicity of five pyrimidines, degradation products of trimethoprim, was deter­mined. These compounds, formed on hydrolysis or oxidation of the drug, are mostly biologically inactive. With the exception of the ketone, which is active against only one of the micro organisms used in the test, all other compounds are devoid of antimicrobial activity and none possesses acute toxicity or phototoxicity.
Aspekte van die anatomie, morfologie en ververing van die kroonkiewiet Vanellus coronatus
Authors: Anderson P. C. , Kok O. B.
Published: July 2013

Aspects of the anatomy and morphology of crowned plovers (Vanellus coronatus) collected over a period of one year at the J.B.M. Hertzog (Bloemfontein) and B.J. Vorster (Kimberley) airports were investigated. The renewal of plumage in both sexes apparently takes place mainly during the summer months. Except for some bill dimensions, all standard body measurements of adult and immature males are significantly larger than those of females. No clear seasonal pattern could be distinguished in the body and liver mass of the birds. Seasonal variations in the visible fat content of adult crowned plovers of both sexes are probably related to breeding activities and the availability of food.
’n Faktoriseringsmetode gegrond op ’n additiewe eienskap
Authors: De la Rosa B. , Mouton H. Du T. , Van der Westhuizen A. , Van Deventer D. , Wessels J. P. H.
Published: July 2013

The purpose of this article is to develop a method of factorisation based on an additive property of the positive integers. Using known results it is emphasised that the composite odd positive integers are precisely those odd numbers that can be represented as sums of three or more consecutive positive integers. The obviously implied algorithm basis is refined in this paper up to a desired level of optimality. The result is an additive-multiplicative basis for an algorithm that is based partly on the said additive property and partly on long division (or alternatively the gcd).
Die ruimtelike vorm van 'n onelastiese, buigbare, geankerde kabel
Authors: Dreyer T. P.
Published: July 2013

Consider an inelastic, perfectly flexible cable with given external forces acting on the total length of the cable. The one end-point is fixed in the origin and the other end-point is anchored at a given point (a;b;c) in space. The resulting configuration of the cable in space can be modelled by a system of non-linear differential equations. In this article it is shown that this continuous model of the cable can always be solved in terms of an integral. In the special case of a constant (i.e. independent of the position on the cable) external force per unit length the solution is given explicitly in terms of three constants that describe the tension at the origin. These three constants are determined by the boundary values a, b and c at the other end-point, and must be calculated in general by a numerical procedure from the three resulting simultaneous non-linear equations. A few applications of this method are shown.
Darwinisme en die bakterieë
Authors: Coetzee J. N.
Published: July 2013

The course of development of the theory of evolution at the turn of the century hardly influenced early bacteriology, and reasons for the lack of a reliable phylogenetic classification of bacteria at the time are presented. Causes for adoption of the doctrine of the inheritance of acquired characteristics in bacteria, in an effort to explain the wonderful adaptability of bacterial populations, are examined. This doctrine prevailed until at least the mid-forties. Experimental results then started appearing which indicated that adaptive mutants arose as a result of random mutations which were only subsequently selected at phenotypic level.
Die ultrastrukturele, morfometriese evaluering van die mikrotubulere stelsel in gestimuleerde B-selle van die pankreas
Authors: Crous A. , De Beer A. M. , Visser E. J.
Published: July 2013

The intracellular distribution of microtubules in pancreatic B-cells was studied morphometrically to elucidate the positive correlation between microtubular content and the rate of insulin release found by biochemical investigations. Rat islet tissue was glucose stimulated under in vivo and in vitro (isolated islets) conditions and tissue samples taken to represent both phases of the phasic insulin response. Electron micrographs (x40 000) of individual B-cells were assembled into montages to obtain complete cell profiles at high magnification.
Die ontwikkeling en implementering van ’n saamgestelde omsetter vir gebruik in sonenergiestelsels
Authors: Hartman S. J. B.
Published: July 2013

The converter proposed here is a compound photovoltaic converter system that has been implemented with a power rating of 1,5 kVA at an array voltage of 96 V, using a 24 V battery bank. The converter system combines the functions of inversion, battery regulation and maximum power point tracking of the solar array into a single cost-effective converter. Maximum power point tracking is performed by controlling the voltage and frequency of the AC output. A description of this converter, and an explanation of the control strategy employed, are provided together with practical results measured on the prototype converter. This compound topology has a high conversion efficiency from solar array to load.
Oorgangsgedrag van ’n voertuigbladveer
Authors: Bester C. R. , Van Schoor M. C.
Published: July 2013

The quasi-static and dynamic force transfer characteristics of an asymmetric tapered leafspring of a South African truck were experimentally determined by measuring the direction dependent stiffnesses and lowest natural frequency. The test results were also used to verify and modify a Rayleigh-Ritz dynamic model of the spring.
Verbeterde voorgeboortesorg by Tygerberg Hospitaal
Authors: Odendaal H. J.
Published: July 2013

Because the high perinatal mortality rate of Cape Coloured patients served by Tygerberg Hospital was of great concern, we initiated several research projects to address this problem. At first we planned three separate studies to ascertain the causes of perinatal deaths. Abruptio placentae and preterm labour were identified as the two most common causes. Several studies were then done to assess risk factors for abruptio placentae and to establish how foetal distress due to abruptio placentae could be detected earlier. At the same time we also concentrated on improving our antenatal care and foetal assessment. All relevant findings of our research projects were immediately implemented clinically. A marked decrease in the perinatal mortality rate of patients with severe pre-eclampsia was achieved, as well as a decline in the overall rate.
Voedselproduksie in ontwikkelende lande - die rol van plantbiotegnologie
Authors: Ferreira D. I.
Published: July 2013

The world is facing major problems with regard to food production. Agricultural land suffers from various conditions which make it less efficient for crop production while the rapid population growth, especially in developing countries, raises concern for sustainable food production. The Green Revolution has failed to secure sustainable food production and it is hoped that biotechnology will facilitate the transition to more sustainable agriculture. Excellent progress has been made with both Cell Biology (tissue culture) and Molecular Biology (genetic engineering).
Die gebruik van mitochondriale DNA-ondersoeke in geregtelik-geneeskundige wetenskappe
Authors: Dawson S. , Weitz C. , Pitout M. J.
Published: July 2013

A variety of methods was developed to characterize mtDNA. The initial aim of these techniques was to try and link diseases with specific mitochondrial defects. As a result of the maternal inheritance trait of mtDNA these techniques facilitate studies of the phylogenetic history and population structure of the human population. It has been shown that mitochondrial DNA typing can be of great value for human identification in forensic cases. The identification of victims of mass-disasters or mass-murders, where human remains can be recovered only after many years have passed, is one of the most challenging fields of forensic identification. By using automated DNA sequencing with fluorescent labels, mitochondrial DNA sequences can be generated rapidly and accurately. Computer software facilitates the rapid comparison of individual and reference sequences.
Nuwe insigte oor Kaapvaalse geologic en mineraalbronne spruit uit ’n rigoristiese komontledingsmetode
Authors: Office Editorial
Published: July 2013

Attempts to derive the geohistory of the Kaapvaal Province without a scientifically disciplined methodology incorporating all the relevant events in their correct interactive temporal relationships have led to costly errors. Episodic charts record all other events against a chronostratigraphic column converted from a lithostratigraphic equivalent employing sequence stratigraphic techniques. Geochronometric charts transform the relative sequence so derived into an approximation of real time, by means of isotopic age dating of marker beds. The predictive power of these charts enables both research and mineral exploration to be goal-orientated.
Wêreldmededingendheid en die tegnologie
Authors: Pistorius C. W. I.
Published: July 2013

In addition to the challenges which the Reconstruction and Development Programme (RDP) poses to South Africa, the country must also be aware of the changing global environment, especially the increasing importance of economic security as a component of national security. The concept of competitiveness is manifested as a goal to be pursued in order to negotiate the emerging global economic struggle. Technology is an important driver of economic prosperity and of the most important keys to international competi­tiveness. Technological innovation is the process through which technology must be leveraged to obtain this. It is necessary that technology, and specifically technological innovation be managed in a formal way, both on the national and company levels.
Die integrering van prys-/kosteberaming en konstruksiebeplanning - die gerekenariseerde generering van konstruksiebedrywighede
Authors: Bowen P. A. , Erwin G. J. , Le Roux G. K.
Published: July 2013

The fact that traditional price/cost models are unrelated to the construction process renders them largely unsuited to the provision of meaningful price/cost advice. The nature and lengthiness of the construction planning process has precluded its incorporation into price/cost modelling during the pre-tender phase of the traditional building procurement process. The nub of the modelling problem has been how to integrate the complex process of construction planning into the pre-tender price/cost modelling process. In this paper the authors propose the synthesis of artificial intelligence techniques and construction planning techniques, resulting in a conceptual framework for a network-based cost modelling system for use by quantity surveyors in the cost modelling of buildings.
Genetiese merkers in die bloed van diere - ’n geskiedkundige oorsig
Authors: Osterhoff D. R.
Published: July 2013

In this review an attempt is made to list the most important events in the search for genetic markers in the blood of animals. In chronological order there are blood groups, biochemical polymorphisms, lymphocyte antigens and the DNA markers that have been discovered and used in practice.
Die voortplantingsbiologie van Perionyx excavatus (Oligochaeta)
Authors: Koegelenberg F. A.
Published: July 2013

No abstract
Die topkwark
Authors: Tegen R.
Published: July 2013

The importance of the recent discovery of the top-quark at Fermilab in Chicago is reviewed. It is shown that the top-quark is important for Big-Bang physics as well as for the Standard Model of Elementary Particle Physics. Relevant literature for further reading can be traced from the list of references given in this short, non-technical article.
Malaria in Suider-Afrika: Profilakse of nie
Authors: Beeslaar J. F.
Published: July 2013

The South African Department of Health recommends that adequate prophylaxis are taken in the event of travelling to endemic malaria areas in Southern Africa as well as internationally. The increasing incidence of multi-drug resistance to the malaria parasite and especially Plasmodium falciparum, necessitated extreme prudence when considering prophylaxis for travellers to these areas.
’n Lede-opname belig die hede en toekoms van die Akademie
Authors: Smit C. F. , Van der Linde M. J.
Published: July 2013

Following a decision by the Board of the Akademie a questionnaire was compiled to conduct a member survey amongst ordinary members of the Akademie during the first months of 2000. The questionnaire was structured to determine the opinions of members on various aspects concerning the Akademie.
Die woordeboek vir meganiese ingenieurs: Vorderingsverslag
Authors: Office Editorial
Published: July 2013

Die komitee van die Nasionale Vakterminologiediens (NVD) wat ’n woordeboek vir meganiese ingenieurswese saamstel en in Januarie 1986 met sy werksaamhede begin het, maak goeie vordering. Die dag-tot-dag-werk word deur 'n redaksiekomitee behartig wat twee keer maandeliks vergader en uit verteenwoordigers van universiteite, SAVD, YSKOR, SABS en ander instansies bestaan.
Respirometrie — soos toegepas op terrestriële en akwatiese invertebrate
Authors: Van Aardt W. J.
Published: July 2013

A review is presented of the apparatus and techniques used to determine the oxygen consumption rate (MO₂) of terrestrial and aquatic invertebrates. The classic manometric method (especially constant pressure respirometry) has been extensively used in the past to measure MO₂. At present this method is still being used with success for small invertebrates weighing less than 1 mg in live weight. The more modern electrochemical techniques have the advantage that measurements can be made over longer time intervals because these instruments are better suited to automation. MO₂ measurements were first performed on aquatic animals with polarographic oxygen sensors. After the invention of the zirkonium oxygen sensor it is now possible to make accurate measurements of MO₂ on bigger terrestrial invertebrates.
Sterrekundewoordeboek
Authors: De Klerk J. H.
Published: July 2013

Gereelde lesers van die S.A. Tydskrif vir Natuurwetenskap en Tegnologie sal weet dat daar reeds die afgelope paar jaar gewerk word aan die nuwe sterrekundewoordeboek. In 'n vorige artikel is daar gemeld dat die werk aan die woordeboek hopelik gedurende 1990 afgehandel sal kan word.
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements?
Authors: Sapart C. J. , Martinerie P. , Witrant E. , Chappellaz J. , van de Wal R. S. W. , Sperlich P. , van der Veen C. , Bernard S. , Sturges W. T. , Blunier T. , Schwander J. , Etheridge D. , Röckmann T.
Published: July 2013

Abstract. Methane is a strong greenhouse gas and large uncertainties exist concerning the future evolution of its atmospheric abundance. Analyzing methane atmospheric mixing and stable isotope ratios in air trapped in polar ice sheets helps in reconstructing the evolution of its sources and sinks in the past. This is important to improve predictions of atmospheric CH4 mixing ratios in the future under the influence of a changing climate. The aim of this study is to assess whether past atmospheric δ13C(CH4) variations can be reliably reconstructed from firn air measurements. Isotope reconstructions obtained with a state of the art firn model from different individual sites show unexpectedly large discrepancies and are mutually inconsistent. We show that small changes in the diffusivity profiles at individual sites lead to strong differences in the firn fractionation, which can explain a large part of these discrepancies. Using slightly modified diffusivities for some sites, and neglecting samples for which the firn fractionation signals are strongest, a combined multi-site inversion can be performed, which returns an isotope reconstruction that is consistent with firn data. However, the isotope trends are lower than what has been concluded from Southern Hemisphere (SH) archived air samples and high-accumulation ice core data. We conclude that with the current datasets and understanding of firn air transport, a high precision reconstruction of δ13C of CH4 from firn air samples is not possible, because reconstructed atmospheric trends over the last 50 yr of 0.3–1.5 ‰ are of the same magnitude as inherent uncertainties in the method, which are the firn fractionation correction (up to ~2 ‰ at individual sites), the Kr isobaric interference (up to ~0.8 ‰, system dependent), inter-laboratory calibration offsets (~0.2 ‰) and uncertainties in past CH4 levels (~0.5 ‰).
Atmospheric mercury over sea ice during the OASIS-2009 campaign
Authors: Steffen A. , Bottenheim J. , Cole A. , Douglas T. A. , Ebinghaus R. , Friess U. , Netcheva S. , Nghiem S. , Sihler H. , Staebler R.
Published: July 2013

Abstract. Measurements of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (PHg) were collected on the Beaufort Sea ice near Barrow, Alaska, in March 2009 as part of the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) and OASIS-Canada International Polar Year programmes. These results represent the first atmospheric mercury speciation measurements collected on the sea ice. Concentrations of PHg averaged 393.5 pg m−3 (range 47.1–900.1 pg m−3) and RGM concentrations averaged 30.1 pg m−3 (range 3.5–105.4 pg m−3) during the two-week-long study. The mean concentration of GEM during the study was 0.59 ng m−3 (range 0.01–1.51 ng m−3) and was depleted compared to annual Arctic ambient boundary layer concentrations. It is shown that when ozone (O3) and bromine oxide (BrO) chemistry were active there is a positive linear relationship between GEM and O3, a negative one between PHg and O3, a positive correlation between RGM and BrO, and none between RGM and O3. For the first time, GEM was measured simultaneously over the tundra and the sea ice. The results show a significant difference in the magnitude of the emission of GEM from the two locations, with significantly higher emission over the tundra. Elevated chloride levels in snow over sea ice are proposed to be the cause of lower GEM emissions over the sea ice because chloride has been shown to suppress photoreduction processes of RGM to GEM in snow. Since the snowpack on sea ice retains more mercury than inland snow, current models of the Arctic mercury cycle may greatly underestimate atmospheric deposition fluxes because they are based predominantly on land-based measurements. Land-based measurements of atmospheric mercury deposition may also underestimate the impacts of sea ice changes on the mercury cycle in the Arctic. The predicted changes in sea ice conditions and a more saline future snowpack in the Arctic could enhance retention of atmospherically deposited mercury and increase the amount of mercury entering the Arctic Ocean and coastal ecosystems.