Functional electrical stimulation (FES) devices have direct applications in the realm of rehabilitation engineering, physiotherapy, occupational therapy and medicine for research, diagnostic and therapeutic purposes. This thesis presents a novel electrical stimulator for use in a FES system. The stimulator produces regulated current pulses using two switched mode power supplies (SMPS) in series. The first power stage - a flyback converter - steps up the supply voltage using primary side digital control. The second power stage is a buck converter with output current hysteretic control. An output switched capacitor circuit shapes the current pulses. All pulse variables are programmable and various pulses can be formed for virtually any FES application. Compared to previous FES devices, the pulses generated here are sharper, have faster rise time and the amplitude and temporal characteristics are more tightly regulated. A single channel prototype system is implemented and experimental results are shown.

Functional electrical stimulation (FES) devices have direct applications in the realm of rehabilitation engineering, physiotherapy, occupational therapy and medicine for research, diagnostic and therapeutic purposes. This thesis presents a novel electrical stimulator for use in a FES system. The stimulator produces regulated current pulses using two switched mode power supplies (SMPS) in series. The first power stage - a flyback converter - steps up the supply voltage using primary side digital control. The second power stage is a buck converter with output current hysteretic control. An output switched capacitor circuit shapes the current pulses. All pulse variables are programmable and various pulses can be formed for virtually any FES application. Compared to previous FES devices, the pulses generated here are sharper, have faster rise time and the amplitude and temporal characteristics are more tightly regulated. A single channel prototype system is implemented and experimental results are shown.

Kinesins are molecular motors that transport intracellular cargos along microtubules (MTs) and influence the organization and dynamics of the MT cytoskeleton. Their force-generating functions arise from conformational changes in their motor domain as ATP is bound and hydrolyzed, and products are released. In the budding yeast Saccharomyces cerevisiae, the Kar3 kinesin forms heterodimers with one of two non-catalytic kinesin-like proteins, Cik1 and Vik1, which lack the ability to bind ATP, and yet they retain the capacity to bind MTs. Cik1 and Vik1 also influence and respond to the MT-binding and nucleotide states of Kar3, and differentially regulate the functions of Kar3 during yeast mating and mitosis. The mechanism by which Kar3/Cik1 and Kar3/Vik1 dimers operate remains unknown, but has important implications for understanding mechanical coordination between subunits of motor complexes that traverse cytoskeletal tracks. In this study, we show that the opportunistic human fungal pathogen Candida albicans (Ca) harbors a single version of this unique form of heterodimeric kinesin and we present the first in vitro characterization of this motor. Like its budding yeast counterpart, the Vik1-like subunit binds directly to MTs and strengthens the MT-binding affinity of the heterodimer. However, in contrast to ScKar3/Cik1 and ScKar3/Vik1, CaKar3/Vik1 exhibits weaker overall MT-binding affinity and lower ATPase activity. Preliminary investigations using a multiple motor motility assay indicate CaKar3/Vik1 may not be motile. Using a maltose binding protein tagging system, we determined the X-ray crystal structure of the CaKar3 motor domain and observed notable differences in its nucleotide-binding pocket relative to ScKar3 that appear to represent a previously unobserved state of the active site. Together, these studies broaden our knowledge of novel kinesin motor assemblies and shed new light on structurally dynamic regions of Kar3/Vik1-like motor complexes that help mediate mechanical coordination of its subunits. / Thesis (Master, Biochemistry) -- Queen's University, 2012-02-29 17:15:03.654

No description available.

<p>The current study aimed to describe the extent and reasons for substituting and switching HAART at the Katutura Intermediate Hospital in Windhoek, Namibia</p>

Parengtas bakalauro baigiamasis darbas yra skirtas suprojektuoti ir pagaminti automatinio rezervo įjungimo skydo prototipą, kurį būtų galima naudoti laboratoriniams darbams universitete.Šio darbo paskirtis yra papildyti elektros aparatų discipliną dar vienu, dažnai sutinkamu ir naudojamu visame pasaulyje stendu, paaiškinant jo veikimo principą, galimybes. Darbe aiškiai yra išdėstomos visos stendo dalys, stendui keliami reikalavimai, parodomos principinė ir valdymo schemos, paaiškinamas detalus veikimas, stendo valdiklio programos algoritmas. Taip pat supažindinama su Lucas-neulle mokomuoju dviejų atskirų tiekimo linijų stendu, parodant visas jo sudedamąsias dalis ir jas trumpai paaiškinant. / ATS helps to avoid serious problems in healthcare facilities for example by the same time when surgery is being held to save human lives and power supply interference occurs, it safely automatically switches power supply mains with no effect to the user. In industry it helps to avoid any power supply problems which every single of them could lead to destruction of expensive machinery or even harm people. Considering problems occurring in power supply lines, this was a great inspiration to produce automatic transfer switch prototype as my Bachelors degree thesis. Since Electrical Engineering Department had no real ATS system prototype before, it will surely supply existing basis and will help students to gain useful experience. Furthermore, all the details about ATS are expounded and will lead to full understanding of the system.

Chez les eucaryotes pluricellulaires, la différenciation des cellules repose en partie sur l'activation oula répression des gènes. Les profils d'expression génique mis en place vont perdurer d'une générationcellulaire à l'autre. Ce phénomène met en jeu des mécanismes épigénétiques qui remodèlentlocalement la structure de la chromatine. Chez Drosophila melanogaster, les protéines des groupesPolycomb (PcG) et Trithorax (TrxG) participent au maintien du profil d'expression des gènes au coursdu développement. Les protéines PcG maintiennent les gènes réprimés tandis que les protéines TrxGmaintiennent les gènes activés. Une troisième classe de protéines nommée Enhancers of Trithoraxand Polycomb (ETP) module l'activité des PcG et TrxG. Dorsal Switch Protein 1 (DSP1) est uneprotéine HMGB (High Mobility Group B) classée comme une ETP. Par tamisage moléculaire, nousavions montré que la protéine DSP1 était présente au sein de complexes de poids moléculaire de 100kDa à 1 MDa. Le travail de thèse présenté ici a pour but d'identifier les partenaires de la protéineDSP1 dans l'embryon et de mieux connaître les propriétés biochimiques de DSP1. Premièrement, j'aimis en place puis effectué l'immunopurification des complexes contenant DSP1 dans des extraitsprotéiques embryonnaires. Cette approche nous a permis d'identifier 23 partenaires putatifs de laprotéine DSP1. Parmi ces protéines, nous avons identifié la protéine Rm62 qui est une ARN hélicaseà boîte DEAD. Les relations biologiques entre DSP1 et Rm62 ont été précisées. Deuxièmement, j'aidéterminé, par une approche biochimique, de nouvelles caractéristiques physico-chimiques de laprotéine DSP1.

The sharing of the terrestrial TV frequency spectrum with Secondary Users (SUs) is presently the focus point of numerous research efforts worldwide. In many regulatory domains, contiguous blocks of VHF and UHF spectrum are available for exclusive use by the terrestrial TV broadcasting incumbents. However, this notion is currently challenged by the spectrum management paradigm of Dynamic Spectrum Access (DSA), advocating that this spectrum may be shared on a dynamic basis with SUs. The migration of analogue terrestrial TV to Digital Terrestrial Television (DTT) has also catalysed the notion that the terrestrial TV frequency spectrum will no longer be exclusively used for terrestrial broadcasting. Some administrations have already embraced this technology, reforming spectrum policy to allow unlicensed secondary access to the Spectral Opportunities (SOs) present in the terrestrial TV frequency bands. The Independent Communications Authority of South Africa (ICASA) has expressed early interest in the possibilities of TV white space technology and its possible utility in exploiting the SOs that exist in the terrestrial TV frequency bands. Core to the issues mentioned above is the quantification of the Spectral Opportunity (SO) available. To this end, the work presented in this thesis gives a quantified estimate of the SO available in South Africa. This work is the first of its kind for the South African environment and uncovers new knowledge regarding SO in South Africa. SO is analysed and quantified on provincial and national level for three discrete points in time: before the start of dual-illumination, during dual illumination and after analogue switch-off. A system model that is able to produce the required geo-referenced field strength coverage and SO maps is conceptualised and implemented. A complete standards compliant model is implemented from scratch, verified and validated, with design decisions specific to the South African context. The analysis methodology is developed with rigour. The construction of the TV transmitter database, definition of incumbent protection criteria and development of the required analysis metrics to quantify SO are presented. SO in the VHF and UHF terrestrial TV frequency bands is quantified by expressing SO in terms of the number of available channels, weighted respectively by land area and population density. The analysis results indicate that significant SO is available for exploitation by TV white space devices in the terrestrial TV spectrum in South Africa. The effects of radio astronomy advantage areas on the SO available are also investigated. The probability of finding contiguous channels in the Very High Frequency (VHF) and Ultra High Frequency (UHF) bands is also quantified. A comparative study, comparing the SO for South Africa with related work in Europe and the United States of America (USA), is also performed. Finally, maps that visualise the SO available are constructed for the three discrete time periods evaluated. / Thesis (PhD (Computer Engineering))--North-West University, Potchefstroom Campus, 2013

The sharing of the terrestrial TV frequency spectrum with Secondary Users (SUs) is presently the focus point of numerous research efforts worldwide. In many regulatory domains, contiguous blocks of VHF and UHF spectrum are available for exclusive use by the terrestrial TV broadcasting incumbents. However, this notion is currently challenged by the spectrum management paradigm of Dynamic Spectrum Access (DSA), advocating that this spectrum may be shared on a dynamic basis with SUs. The migration of analogue terrestrial TV to Digital Terrestrial Television (DTT) has also catalysed the notion that the terrestrial TV frequency spectrum will no longer be exclusively used for terrestrial broadcasting. Some administrations have already embraced this technology, reforming spectrum policy to allow unlicensed secondary access to the Spectral Opportunities (SOs) present in the terrestrial TV frequency bands. The Independent Communications Authority of South Africa (ICASA) has expressed early interest in the possibilities of TV white space technology and its possible utility in exploiting the SOs that exist in the terrestrial TV frequency bands. Core to the issues mentioned above is the quantification of the Spectral Opportunity (SO) available. To this end, the work presented in this thesis gives a quantified estimate of the SO available in South Africa. This work is the first of its kind for the South African environment and uncovers new knowledge regarding SO in South Africa. SO is analysed and quantified on provincial and national level for three discrete points in time: before the start of dual-illumination, during dual illumination and after analogue switch-off. A system model that is able to produce the required geo-referenced field strength coverage and SO maps is conceptualised and implemented. A complete standards compliant model is implemented from scratch, verified and validated, with design decisions specific to the South African context. The analysis methodology is developed with rigour. The construction of the TV transmitter database, definition of incumbent protection criteria and development of the required analysis metrics to quantify SO are presented. SO in the VHF and UHF terrestrial TV frequency bands is quantified by expressing SO in terms of the number of available channels, weighted respectively by land area and population density. The analysis results indicate that significant SO is available for exploitation by TV white space devices in the terrestrial TV spectrum in South Africa. The effects of radio astronomy advantage areas on the SO available are also investigated. The probability of finding contiguous channels in the Very High Frequency (VHF) and Ultra High Frequency (UHF) bands is also quantified. A comparative study, comparing the SO for South Africa with related work in Europe and the United States of America (USA), is also performed. Finally, maps that visualise the SO available are constructed for the three discrete time periods evaluated. / Thesis (PhD (Computer Engineering))--North-West University, Potchefstroom Campus, 2013

The goal of the research reported in this thesis is to establish the feasibility of a novel optical architecture for an optical route & select circuit switch suitable for implementation as a photonic integrated circuit. The proposed architecture combines Optical Phased Array (OPA) switch elements implemented as multimode interference coupler based Generalised Mach-Zehnder Interferometers (GMZI) with a planar Lüneburg lens-based optical transpose interconnection network implemented using graded metamaterial waveguide slabs. The proposed switch is transparent to signal format and, in principle, can have zero excess insertion loss and scale to large port counts. These switches will enable the low-energy consumption high capacity communications network infrastructure needed to provide environmentally-friendly broadband access to all. The thesis first explains the importance of switch structures in optical communications networks and the difficulties of scaling to a large number of switch ports. The thesis then introduces the Talbot effect, i.e. the self-imaging of periodic field distributions in free space. It elaborates on a new approach to finding the phase relations between pairs of Talbot image planes at carefully selected positions. The free space Talbot effect is mapped to the waveguide Talbot effect which is fundamental to the operation of multimode interference couplers (MMI). Knowledge of the phase relation between the MMI ports is necessary to achieve correct operation of the GMZI OPA switch elements. An outline of the design procedures is given that can be applied to optimise the performance of MMI couplers and, as a consequence, the GMZI OPA switch elements. The Lüneburg Optical Transpose Interconnection System (LOTIS) is introduced as a potential solution to the problem of excessive insertion loss and cross-talk caused by the large number of crossovers in a switch fabric. Finally, the thesis explains how a Lüneburg lens may be implemented in a graded ‘metamaterial’, i.e. a composite material consisting of ‘atoms’ arranged on a regular lattice suspended in a host by nano-structuring of silicon waveguide slabs using a single etch-step. Furthermore, the propagation of light in graded almost-periodic structures is discussed. Detailed consideration is given to the calibration of the local homogenised effective index; in terms of the local parameters of the metamaterial microstructure in the plane and the corrections necessary to accommodate slab waveguide confinement in the normal to the plane. The concept and designs were verified by FDTD simulation. A 4×4 LOTIS structure showed correct routing of light with a low insertion loss of -0.25 dB and crosstalk of -24.12 dB. An -0.45 dB excess loss for 2D analysis and an -0.83 dB insertion excess loss for 3D analysis of two side by side metamaterial Lüneburg lenses with diameter of 15 μm was measured, which suggests that the metamaterial implementation produces minimal additional impairments to the switch.