242 research outputs found
Realisatie van PAL-coder t.b.v. elektronisch schoolbord
No full textRe gerealiseerde schakeling is een sterk gereduceerde PAL-coder, afgeleid van een PALcoder zoals die voor T.V.- doeleinden wordt gebruikt. Er kan gekozen worden uit vier kleuren voor de weergave van gekleurde lijnen tegen een gekleurde achtergrond. De kleurvektoren zijn orthogonaal en vertegenwordigen de kleuren blauw, rood, geel en groen.Electrical Engineering, Mathematics and Computer ScienceTransmissie van Informati
Computerized coding of medical problem statements and the Baylor Coder
No full textDue to the narrow range of medical problem statements that regularly appear in medical practice, a modified table look-up procedure can successfully code medical problem statements. Medical problem statements are noun phrases that must fit into rather arbitrary classification schemes. Principles from morphology, semantics, syntax, and quantification linguistics provide some guidelines for designing a coder. The KODIAC coder illustrates how 90% accuracy can be achieved with modified table look-up. Mechanisms of the Baylor coder include compression of words and many table options. This author has collected data to assess the accuracy of the Baylor coder and to assess the difficulty of modifying the Baylor table. The Baylor coder is only 79% accurate but has only 1,400 rows in its table, while the KODIAC table has 6,000 rows. At the moment, the cost of improving the Baylor coder is difficult to compare to the cost of obtaining an effective KODIAC-like coder.Computer Science, Department o
7-Bits PCM coder en decoder voor demonstratiedoeleinden
No full textNa een inleidende beschouwing over puls code modulatie wordt de schakeling van de 7-bits coder-decoder nader besproken. Speciale aandacht wordt besteed aan de problemen, die optreden bij het 7-bits systeem in vergelijking tot het 5-bits systeem waarop de schakeling gebaseerd is. Tot slot volgen enige metingen inzake signaalruis verhoudingen.Electrical Engineering, Mathematics and Computer ScienceTransmissie van Informati
Development and leadership in computer-mediated collaborative groups
Get PDFComputer-mediated collaboration is an important feature of modern organisational and educational settings. Despite its ever increasing popularity, it is still commonly compared unfavourably with face-to-face collaboration because non-verbal and paralinguistic cues are minimal. Although research on face-to-face group collaboration is well documented, less is known about computer-mediated collaboration.
The initial focus of this thesis was an in-depth analysis of a case study of a computer-mediated collaborative group. The case study was a large international group of volunteer researchers who collaborated on a two-year research project using asynchronous communication (email). This case study was a window on collaborative dialogue in the early 1990s (1992-94) at a time when information and communication technologies were at an early stage of development.
After identifying the issues emerging from this early case study, another case study using technologies and virtual environments developed over the past decade, was designed to further understand how groups work together on a collaborative activity. The second case study was a small group of students enrolled in a unit of study at Murdoch University who collaborated on a series of nine online workshops using synchronous communication (chat room). This case study was a window on collaborative dialogue in the year 2000 when information and communication technologies had developed at a rate which few people envisioned in the early 90s.
The primary aim of the research described in this thesis was to gain a better understanding of how computer-mediated collaborative communities develop and grow. In particular, the thesis addresses questions related to the developmental and leadership characteristics of collaborative groups.
Internet research requires a set of assumptions relating to ontology, epistemology, human nature and methodological approach that differs from traditional research assumptions. A research framework for Internet research - Complementary Explorative Data Analysis (CEDA) - was therefore developed and applied to the two case studies.
The results of the two case studies using the CEDA methodology indicate that computer-mediated collaborative groups are highly adaptive to the aim of the collaborative task to be completed, and the medium in which they collaborate. In the organisational setting, it has been found that virtual teams can devise and complete a collaborative task entirely online. It may be an advantage, but it is certainly not mandatory to have preliminary face-to-face discussions. What is more important is to ensure that time is allowed for an initial period of structuration which involves social interaction to develop a social presence and eventually cohesiveness. In the educational setting, a collaborative community increases pedagogical effectiveness. Providing collaborative projects and interdependent tasks promotes constructivist learning and a strong foundation for understanding how to collaborate in the global workplace. Again, this research has demonstrated that students can collaborate entirely online, although more pedagogical scaffolding may be required than in the organisational setting. The importance of initial social interaction to foster a sense of presence and community in a mediated environment has also been highlighted.
This research also provided greater understanding of emergent leadership in computer-mediated collaborative groups. It was found that sheer volume of words does not make a leader but frequent messages with topic-related content does contribute to leadership qualities.
The results described in this thesis have practical implications for managers of virtual teams and educators in e-learning
Confessions of a Live Coder
No full textThis paper describes the process involved when a live coder decides to learn a new musical programming language of another paradigm. The paper introduces the problems of running comparative experiments, or user studies, within the field of live coding. It suggests that an autoethnographic account of the process can be helpful for understanding the technological conditioning of contemporary musical tools. The author is conducting a larger research project on this theme: the part presented in this paper describes the adoption of a new musical programming environment, Impromptu, and how this affects the author's musical practice
AGING-INDUCED INCREASED SUSCEPTIBILITY TO AUTOIMMUNITY IS DUE TO COMPROMISED NEGATIVE SELECTION IN THE THYMUS RATHER THAN DEFECTS IN REGULATORY T CELLS
No full textPurpose: Immunotolerance generates protection against autoimmunity by deleting self reactive T cells in the thymus through negative selection as well as the generation of natural regulatory T cells (nTregs) that will help suppress autoimmunity in the periphery. Natural aging is associated with a progressive loss of FoxN1 and thymic atrophy, and is also believed to be associated with increased autoimmunity and an increase in suppressive FoxP3+ regulatory T cells (Tregs). Deletion of self-reactive T cells requires self-antigen presentation by medullary thymic epithelial cells (mTECs). We set out to determine if thymic aging, characterized by the progressive loss of FoxN1 and mTEC disruption, alters immunotolerance by influencing negative selection or impacting the generation of suppressive Treg cells. Methods: For thymus population experiments, we induce thymic atrophy in our FoxN1 conditional knockout mice using tamoxifen injections. We then determine expression of CD4+, CD8+, and CD4+8+ double positive, and CD25+FoxP3+ regulatory thymocytes using flow cytometry. The peripheral Treg data is assessed by adoptive transfer of total spleenocytes from young and aged wild type mice into young Rag2-/- mice. Cell populations are determined using flow cytometry. Results: We found that the loss of FoxN1 induced thymic atrophy is associated with an impairment of negative selection, where CD4+ and CD8+ are increased in the thymus while CD4+CD8+ double positive thymocytes are decreased. This indicates that the age atrophied thymus is not able to delete additional single positive thymocytes, and these may be self-reactive thymocytes. Additionally, we found that nTregs in the aged and atrophied thymus are increased in proportion and their suppressor function remains intact. Furthermore, we found that when we transfer aged spleenocytes, in which there are increased Treg and decreased pro-apoptotic Bim protein, and young spleenocytes separately into young Rag2 knockout mice, that the young periphery is able to restore both Bim levels and Treg levels to that of the young mice. Conclusions: We conclude that loss of FoxN1 disrupts thymic mTEC structure and impairs negative selection, which may lead to an increase in self-reactive T cells. However, thymic atrophy does not compromise peripheral Tregs. The function and number of peripheral Tregs is dependent on the micro-environment in which they stay
Compaction Filter as an Optimum Solution for Multirate Subband Coder of Cyclostationary Signals
No full textA consistent theory of optimum subband coding of zero mean wide-sense cyclostationary signals with N-periodic statistics is presented in this paper. Blocked polyphase representation of the analysis and synthesis filter banks is introduced as an effective way of multirate subband coder description. Optimum energy compaction using Nyquist-M process is presented as a solution for maximizing the coding gain of the coder. In two definitions and four theorems the author proves that Nyquist-M filters fulfill necessary and sufficient conditions imposed on subband signals. Results from Matlab simulations are presented to support theoretical conclusions
Onderzoek naar de realiseerbaarheid van een negen bits PCM "coder" voor breedbandsignalen,die codeert volgens de Gray-code,aan de hand van een drie bits proefmodel
No full textNa een uiteenzetting van de soort signalen, die we willen ooderen, wordt een verklaring gegeven van de principe werking van de "coder”, die we willen gebruiken. Vervolgens wordt gezocht naar een geschikte uitvoeringsvorm voor de versterkers die toegepast moeten worden in de trappen van de ''coder". Het een en ander wordt toegelicht met de te stellen eisen aan deze versterker. De gekozen versterkerschakeling, die in grote trekken overeenkomt met een uitvoering, die door de ''Bell-Laboratories werd gepublipeerd, wordt vervolgens toegepast in een drie bits proefschakeling. Van deze schakeling worden de meetresultaten en de afregelvoorsshriften gegeven. Ten slotte geven de slotconoluaies een overzicht over de bereikte resultaten en de te verwachten uitbreidingsmogelijkheden van de proefschakeling.Applied SciencesElectrotechniekTransmissie van Informati
Thymic involution perturbs negative selection and leads to chronic inflammation
No full textThe ubiquitous presence of chronic low-level pro-inflammatory factors in elderly individuals (termed inflammaging) is a significant risk factor for morbidity and mortality. The etiology of inflammaging is largely unknown. Recent evidence has identified the persistent activation of immune cells, thought to arise from latent viral infections, as key contributors towards the development of a chronic inflammatory environment. However, the contribution of autoreactive T cells towards the development of inflammaging has yet to be investigated. Another pervasive feature of the aging process is the age-related involution of the thymus gland, which has been linked with a predisposition toward developing autoimmunity. In the present study, we determined how age-related thymic involution leads to the persistent release and activation of autoreactive T cells capable of inducing inflammaging. We utilized a FoxN1 conditional knock-out (FoxN1-cKO) mouse model that mimics thymic involution while maintaining a young periphery and naturally aged C57Bl/6 mice. We found that thymic involution leads to T cell activation shortly after thymic egress, which is accompanied by cellular infiltration into non-lymphoid tissues, elevated serum IL-6, and enhanced production of TNFα. Additionally, activated autoreactive T cell clones were detected in the periphery of FoxN1-cKO mice. We determined that a failure of negative selection, facilitated by decreased AIRE expression rather than impaired regulatory T cell (Treg) generation, and led to autoreactive T cell activation in the periphery. Furthermore, we have demonstrated that the young environment can reverse the age-related accumulation of Tregs but not inflammatory infiltration. Together, these findings identify thymic involution and the persistent activation of autoreactive T cells as a source of chronic age-related inflammation (inflammaging)
Comparisons of the execution times and memory requirements for high-speed discrete fourier transforms and fast fourier transforms, for the measurement of AC power harmonics
No full textConventional wisdom dictates that a Fast Fourier Transform (FFT) will be a more computationally effective method for measuring multiple harmonics than a Discrete Fourier Transform (DFT) approach. However, in this paper it is shown that carefully coded discrete transforms which distribute their computational load over many frames can be made to produce results in shorter execution times than the FFT approach, even for large number of harmonic measurement frequencies. This is because the execution time of the presented DFT actually rises with N and not the classical N2 value, while the execution time of the FFT rises with Nlog2N
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