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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Photodétecteurs organiques : conception, caractérisation et étude des mécanismes de défaillance / Organic photodetectors : design, characterization and study of degradation mechanisms

Kielar, Marcin 04 November 2016 (has links)
Cette thèse concerne l’étude des photodétecteurs à base de matériauxsemi-conducteurs organiques (OPDs) sensibles à la lumière verte. Ces travaux sedivisent en cinq parties distinctes. Tout d’abord, une recherche bibliographique suiviedes notions fondamentales sur les matériaux et le fonctionnement des dispositifsorganiques est présentée. Ensuite, un travail sur la méthodologie concernant lafabrication de bancs expérimentaux et sur la métrologie garantissant l’exactitude desdonnées expérimentales sont effectués. Les méthodes de fabrication etd’optimisation, notamment le dépôt par sérigraphie, sont également présentées. Lapartie expérimentale concerne l’étude de l’origine du courant d’obscurité dans lesstructures organiques à base des matériaux donneur et accepteur d’électrons, laconception et la caractérisation d’un photodétecteur organique à l’état de l’art dontles performances optoélectroniques sont proches des dispositifs inorganiques baséssur la technologie silicium. Enfin, l’étude des mécanismes de dégradation d’uncapteur organique est présentée mettant en avant le rôle de l’oxygène et l’humidité. / This thesis deals with the study of photodetectors based on organicsemiconductor materials (OPDs) that are sensitive to green light. There are five partsto this study. First, a bibliographic study following the fundamentals of organicmaterials and the working principle of organic photodetectors is presented. Then, anextended study on the methodology and metrology is detailed, which was carried outin order to design and fabricate new optoelectronic instruments that are able tocharacterize organic devices accurately. Fabrication and optimization steps oforganic photodetectors are detailed. The experimental section concerns the study onthe origin of the dark current in organic devices based on electron donor/acceptorsystems. A choice of materials is discussed and a full characterisation of state-of-theartorganic photodetectors is presented in detail. The measured performances wereclose to the those of inorganic sensors based on silicon technology. Finally, a studyof degradation mechanisms is presented which highlights the role of oxygen andmoisture.
302

Identification and Validation of Small Molecules Inhibiting Human Adenovirus Replication

Saha, Bratati 01 October 2019 (has links)
Human adenovirus (HAdV) mainly causes minor illnesses, but can lead to severe disease and death in both immunocompromised and immunocompetent patients. In such cases, the current standards of treatment often do not improve disease outcome and no approved antiviral therapy against HAdV exists. Since HAdV relies on cellular machinery to assist in the progression of the virus lifecycle, we hypothesized that small molecules targeting certain cellular proteins/pathways, without severely affecting cell health, may serve as effective anti-HAdV compounds. Thus, we aimed to identify novel inhibitors of HAdV, and investigate the molecular mechanism to determine new therapeutic targets for intervention in HAdV infection. We first examined the antiviral properties of pan-histone deacetylase (HDAC) inhibitor SAHA and found that the drug affects multiple stages of the HAdV lifecycle, resulting in significant reductions in virus yield. SAHA was effective in decreasing gene expression from clinically relevant HAdV serotypes. Subsequent investigations on the role of HDACs in HAdV infection led us to determine that class I HDAC activity, mainly HDAC2, is necessary for optimal viral gene expression. Using a wildtype-like HAdV reporter construct that allows us to monitor virus replication by fluorescence microscopy, we then designed an efficient system for screening small molecules to identify novel HAdV inhibitors. We screened over 1300 small molecules, and the screen was sensitive enough to detect compounds with both robust and modest antiviral activity. Several positive hits were validated to reduce HAdV gene expression and yield from infected cells. Further investigation on the efficacy of these compounds and the mechanism behind their inhibition of HAdV can lead to the discovery of new pharmacological targets and the development of more effective antivirals.
303

The new American vortex : explorations of McLuhan : a dissertation presented in partial fulfilment of the requirements for the degree of Ph.D. in Media Studies at Massey University, Palmerston North, Aotearoa/New Zealand

Chrystall, Andrew Brian January 2007 (has links)
To encounter and digest the oeuvre of H. Marshall McLuhan on his own terms, this study deploys a strategy not dissimilar to that of Poe’s sailor who survived his descent into the maelstrom by studying the action of the vortex and catching hold of a recurring form. Here, McLuhan’s career-spanning concern with “communication” may be seen as just such a recurrence — his concern with communication is evident at every turn of his effort to update the Great English Vortex of 1914 and develop a second vortex in mid-century America. Having taken hold of this central concern, this study uses the procedure he developed to expose the “theory of communication” of any figure in the arts and sciences, and applies it to McLuhan himself. In this process of folding McLuhan in on himself, five loosely chronological chapters are used to reveal the four historical “phases” of his career, and to show that McLuhan cannot properly be understood apart from: 1. The great tradition of Ciceronian humanism and the Ciceronian ideal —the doctus orator — a figure in whom eloquence and wisdom coalesce. 2. The programme of the figures frequently referred to as the Men of 1914: James Joyce, Ezra Pound, T. S. Eliot, and Wyndham Lewis. In the final analysis, McLuhan is shown as having updated and transformed both — the Ciceronian ideal and the programme of the Men of 1914 — to become something of a singularity in the midst of what he saw as an Electric Renaissance: a paramodern (neither modernist nor post-modernist) doctus orator.
304

Monitor setups for IT helpdesk workers: a comparison study

Whalley, Sarah Marie Unknown Date (has links)
In the hectic world of an IT helpdesk with an ever increasing number of applications and tasks on the go, managing the intricacies of how to navigate these is a cause of frustration for helpdesk workers. I had noticed while working on a helpdesk that the workspace area - particularly the monitor setups that IT helpdesk workers have to use - makes doing their job difficult. The number of applications open, the number of tasks on the go at once and the added pressure of customer contact, all call for applications and data to be accessed quickly - but the set up of the users workspace generally does not allow for this. The main objective of this research is to compare the difference between the use of a single screen, a dual screen and the new Multi-Layer Display (MLD) and the complications of having multiple applications and multiple monitors operating at one time for IT Helpdesk Workers. This research looked at how the users' monitor setup influenced the performance, efficiency, satisfaction, ergonomics and learning of the participants.The research showed that there was a clear dislike of the current set up of single screens; all participants felt that the single screen setup limited what they could do at once and it rated the least favourite of all. The dual and MLD screens showed positive outcomes for increasing multi-tasking abilities and raising users' perceived performance and satisfaction levels. The added screen real estate of both the dual and MLD over the single screen meant that users consistently had more information available to them 7which enabled them to complete tasks quicker, monitor other applications for incoming jobs, easily transfer data from one application to another and multi-task more effectively. While there were some minor ergonomic concerns and learning difficulties with the unique features and utilities of the both the dual and MLD monitors, participants still preferred to use these setups over the single screen.
305

Three Essays on the Impact of Electronic Screen Trading in Futures Markets

Hill, Amelia Mary January 2001 (has links)
This dissertation consists of 3 essays that examine the impact of electronic screen trading in futures markets. The research provides empirical evidence on increasingly significant issues given the rapid global advances in technology used in securities markets. Each essay addresses the scarcity of conclusive research in order to aid researchers, regulators, exchange policy makers and systems builders as they confront issues related to electronic trading systems.
306

In-Vehicle Screen Density : Driver distraction and User Preferences for Low vs High Screen Densisty

Johansson, Hanna, Walter, Katarina January 2005 (has links)
<p>Many information technology artefacts can be found in today’s cars. The interaction with these artefacts is the driver’s secondary task while driving the car in a safe way is the primary task. When designing interfaces for in-vehicle usage, measures have to be taken in order to make the interaction with the artefact suit the in-vehicle environment. One of these measures is to have the appropriate screen density level, which is the amount of information present on the screen.</p><p>This thesis compares the usability of two integrated in-vehicle display prototypes, one with low screen density and one with high screen density. The usability comparison considers both safety and user preferences. Safety was measured by a Lane Change Test (LCT) which measures distraction of a primary task while performing a secondary task, and user preferences was measured with a questionnaire. Before the comparison was made, controls and a graphical user interface were designed.</p><p>Results showed no significant difference in driver distraction between performing tasks on the high screen density display and the low screen density display. However, a vast majority of the users preferred high screen density over low. Furthermore, the distraction levels for both the high and the low screen density displays were below the proposed 0.5 meter limit for allowed driver distraction. The results indicate that in-vehicle displays can have a high level of screen density without imposing a level of distraction on the driver that is unsuitable for driving.</p>
307

Future Upgrades of the LHC Beam Screen Cooling System

Backman, Björn January 2006 (has links)
<p>The topic of this thesis concerns the LHC, the next large particle accelerator at CERN which will start operating in 2007. Being based on superconductivity, the LHC needs to operate at very low temperatures, which makes great demands on the cryogenic system of the accelerator. To cope with the heat loads induced by the particle beam, a beam screen cooled with forced flow of supercritical helium is used.</p><p>There is an interest in upgrading the energy and luminosity of the LHC in the future and this would require a higher heat load to be extracted by the beam screen cooling system. The objective of this thesis is to quantify different ways to upgrade this system by mainly studying the effects of different pressure and temperatures levels as well as a different cooling medium, neon.</p><p>For this a numerical program which simulates one-dimensional pipe flow was constructed. The frictional forces were accounted for by the empirical concept of friction factor. For the fluid properties, software using empirically made correlations was used. To validate the numerical program, a comparison with previous experimental work was done. The agreement with experimental data was good for certain flow configurations, worse for others. From this it was concluded that further comparisons with experimental data must be made in order to tell the accuracy of the mathematical model and the correlations for fluid properties used.</p><p>When using supercritical helium, thermo-hydraulic instabilities may arise in the cooling loop. It was of special interest to see how well a numerical program could simulate and predict this phenomenon. It was found that the numerical program did not function for such unstable conditions; in fact it was much more sensitive than what reality is.</p><p>For the beam screen cooling system we conclude that to cope with the increased heat loads of future upgrades, an increase in pressure level is needed regardless if the coolant remains helium, or is changed to neon. Increasing the pressure level also makes that the problems with thermo-hydraulic instabilities can be avoided. Of the two coolants, helium gave the best heat extraction capacity. Unlike neon, it is also possible to keep the present temperature level when using helium.</p>
308

Inkjet and Screen Printed Electrochemical Organic Electronics

Mannerbro, Richard, Ranlöf, Martin January 2007 (has links)
<p>Linköpings Universitet och Acreo AB i Norrköping bedriver ett forskningssamarbete rörande organisk elektrokemisk elektronik och det man kallar papperselektronik. Målet på Acreo är att kunna trycka denna typ av elektronik med snabba trycktekniker så som offset- eller flexotryck. Idag görs de flesta demonstratorer och prototyper, baserade på denna typ av elektrokemisk elektronik, med manuella och subtraktiva mönstringsmetoder. Det skulle vara intressant att hitta fler verktyg och automatiserade tekniker som kan underlätta detta arbete. Målet med detta examensarbete har varit att utvärdera vilken potential bläckstråleteknik respektive screentryck har som tillverkningsmetoder för organiska elektrokemiska elektroniksystem samt att jämföra de båda teknikernas för- och nackdelar. Vad gäller bläckstråletekniken, så ingick även i uppgiften att modifiera en bläckstråleskrivare avsedd för kontor/hemmabruk för att möjliggöra tryckning av de två grundläggande materialen inom organisk elektrokemisk elektronik - den konjugerade polymeren PEDOT och en elektrolyt.</p><p>I denna uppsats rapporteras om hur en procedur för produktion av elektrokemisk elektronik har utvecklats. Världens första elektrokemiska transistor som producerats helt med bläckstråleteknik presenteras tillsammans med fullt fungerande implementeringar i logiska kretsar. Karaktärisering av filmer, komponenter och kretsar som producerats med bläckstråle- och screentrycksteknik har legat till grund för den utvärdering och jämförelse som har gjorts av teknikerna. Resultaten ser lovande ut och kan motivera vidare utveckling av bläckstrålesystem för produktion av prototyper och mindre serier. En kombination av de båda nämnda teknikerna är också ett tänkbart alternativ för småskalig tillverkning.</p> / <p>Linköping University and the research institute Acreo AB in Norrköping are in collaboration conducting research on organic electrochemical electronic devices. Acreo is pushing the development of high-speed reel-to-reel printing of this type of electronics. Today, most demonstrators and prototypes are made using manual, subtractive patterning methods. More tools, simplifying this work, are of interest. The purpose of this thesis work was to evaluate the potential of both inkjet and screen printing as manufacturing tools of electrochemical devices and to conduct a comparative study of these two additive patterning technologies. The work on inkjet printing included the modification of a commercially available desktop inkjet printer in order to print the conjugated polymer PEDOT and an electrolyte solution - these are the two basic components of organic electrochemical devices. For screen printing, existing equipment at Acreo AB was employed for device production.</p><p>In this report the successful development of a simple system and procedure for the inkjet printing of organic electrochemical devices is described. The first all-inkjet printed electrochemical transistor (ECT) and fully functional implementations of these ECTs in printed electrochemical logical circuits are presented.</p><p>The characterization of inkjet and screen printed devices has, along with an evaluation of how suitable the two printing procedures are for prototype production, been the foundation of the comparison of the two printing technologies.</p><p>The results are promising and should encourage further effort to develop a more complete and easily controlled inkjet system for this application. At this stage of development, a combination of the two technologies seems like an efficient approach.</p>
309

Effects of terrain features on wave propagation: high-frequency techniques

Sarwar, Muhammad January 2009 (has links)
<p>This Master thesis deals with wave propagation and starts with wave propagation basics. It briefly presents the theory for the diffraction over terrain obstacles and describes two different path loss models, the Hata model and a FFT-based model. The significance of this paper is that it gives the simulation results for the models mentioned above and presents a comparison between the results obtained from an empirical formula and the FFT-model. The comparison shows that the approach based on Fast Fourier Transform is good enough for prediction of the path loss and that it is a time efficient method.</p>
310

Cryptosporidium parvum: enhancing our understanding of its unique fatty acid metabolism and the elucidation of putative new inhibitors

Fritzler, Jason Michael 10 October 2008 (has links)
Cryptosporidium parvum is widely known for outbreaks within the immunocompetent population, as well its sometimes excruciating effects as an opportunistic agent in AIDS patients. Our understanding of the biology and host-parasite interactions of this parasitic protist is increasing at a rapid rate due to recent molecular and genetic advances. The topic of our research is in the area of C. parvum fatty acid metabolism, which is highly streamlined in this parasite. In addition to a type I fatty acid synthase (CpFAS1), C. parvum also possesses an enormous type I polyketide synthase (CpPKS1). Because of the size of this megasynthase, functional characterization of the complete enzyme is not possible. We have isolated and characterized the loading unit of CpPKS1 which contains an acyl-[acyl carrier protein (ACP)] ligase (AL) and an ACP. This unit is responsible for the overall substrate selection and initiation of polyketide production. Our data show that CpPKS1 prefers long-chain fatty acids with the highest specificity for arachidic acid (C20). Thus, the final polyketide product could contain as many as 34 carbons. Additionally, C. parvum possesses only a single fatty acid elongase. This family of enzymes serves a mechanism similar to FAS, and many have been found to be involved in de novo fatty acid synthesis in other organisms. After expressing this membrane protein in human cells, we have determined that it too prefers long-chain fatty acyl-CoAs which undergo only one round of elongation. This is in contrast to members of this enzyme family in other organisms that can initiate de novo synthesis from two- or four-carbon fatty acids via several rounds of elongation. Our lab has previously characterized the unique acyl-CoA binding protein (CpACBP1) from C. parvum. Molecular and biochemical data suggested that this enzyme may serve as a viable drug target. We have screened a library of known (and somewhat common) compounds against CpACBP1, and have isolated several potential compounds to be further examined for their ability to inhibit the growth of C. parvum.

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