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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.
11

Design of an integrated streak camera based on a time correlated single photon counting system / Conception d'une caméra à balayage de fente intégrée basée sur un système de comptage de photon unique résolu en temps

Malass, Imane 13 May 2016 (has links)
Nous présentons une caméra à balayage de fente intégrée basée sur un système de comptage de photon unique résolu en temps (TCSPC-SC) employant l'architecture linéaire « streak » pour surmonter la limitation de l'espace inhérent aux systèmes TCSPC bidimensionnels. Cette solution permet l'intégration de fonctionnalités électroniques complexes dans les pixels sans l'inconvénient d'un faible facteur de remplissage conduisant à une faible efficacité de détection. Le TCSPC-SC se compose de deux blocs principaux: une photodiode à avalanche (SPAD) et un bloc de mesure de temps, les deux blocs sont intégrés en technologie 180 nm CMOS standard. La structure de la SPAD utilisée a été sélectionnée parmi 6 structures différentes après un processus de caractérisation précise et approfondie. Le bloc de mesure du temps se compose d'un TOC hybride capable d'atteindre des résolutions de temps élevées et ajustables avec une large dynamique de mesure grâce à un système de conversion de temps (TOC) hybride qui combine l'approche analogique basée sur un convertisseur de temps vers amplitude(TAC), et les approches numériques utilisant une boucle à verrouillage de retard (DLL) et un compteur numérique. Le TOC hybride a été spécialement conçu pour être utilisé dans un système TCSPC qui intègre une ligne de TOC nécessitant ainsi une conception appropriée pour limiter la consommation d'énergie et la surface d'occupation et parvenir à une architecture flexible et facilement extensible. Suite à la conception et la réalisation de ces deux blocs dans une technologie180 nm CMOS standard, une structure de test de la caméra à balayage de fente (TCSPC-SC) qui englobe 8 unités a été réalisée dans le but final de mettre en œuvre un modèle TCSPC-SC complet et plus large. / In this work we present a TCSPC Streak Camera (TCSPC-SC) that takes advantage of the streak mode imaging ta overcome the space limitation inherent ta 20 TCSPC sensor arrays. This cost-effective solution allows the integration of complex functionalities in the pixel without the inconvenience of low fill factor that leads ta low detection efficiency. The TCSPC~SC consists of two main building blacks: a SPAD and a time measurement black bath integrated in 180 nm Standard CMOS technology. The SPAD was selected among 6 different SPAD structures following a thorough characterization process ta fully determine its performance figures. The time measurement black consists of a hybrid TOC capable of achieving high adjustable time resolutions with large dynamic range owing ta a time conversion scheme that combines traditional Analog Time to Amplitude Converter (TAC), Digital DLL-based and counter-based TOC. Furthermore, thehybrid TOC was especially designed ta be used in a TCSPC system that incorporates an array of TDCs which required a careful design ta limit power consumption and occupation area in order to achieve a flexible and easily scalable architecture. These two building blacks were bath fabricated in a 180 nm standard CMOS technology and employed ta demonstrate a TCSPC Streak Camera(TCSPC-SC) test structure that englobes 8 units in order ta demonstrate the system's operation principle with the final aim of implementing a complete and bigger TCSPC-SC model in the near future
12

Charakterisierung der Funktion und Lokalisation der plastidären Genexpressionsmaschinerie in Nicotiana tabacum

Finster, Sabrina 18 June 2015 (has links)
Die Transkription der Chloroplasten ist erstaunlich komplex. Ihr relativ kleines Genom kodiert für Komponenten der Photosynthese und der eigenen Genexpressionsmaschine. Es wird mindestens durch zwei RNA Polymerasen transkribiert. Neben der plastidär kodierten RNA Polymerase (PEP), existiert mindestens eine weitere kernkodierte RNA Polymerase (NEP). Die PEP spielt eine wichtige Rolle bei der Expression der Photosynthesegene und ist essentiell für die Biogenese der Chloroplasten und schließlich für das Überleben der Pflanzen. In der vorliegenden Arbeit wird erstmals die spezifische Interaktion der PEP mit ihren Transkriptionseinheiten unter verschiedenen Lichtbedingungen in vivo auf plastomweiter Ebene gezeigt. Darunter befinden sich hauptsächlich DNA Fragmente, die Photosynthesegene repräsentieren. Außerdem zeigt die PEP eine eindeutige Präferenz zu den rRNA Genen und einigen tRNA Genen. Eine Reduktion dieser Assoziation der PEP in Dunkelperioden lässt einen lichtabhängigen Prozess bei der PEP-DNA Assoziation vermuten. Außerdem wurde die PEP Aktivität an den bestimmten DNA Regionen in vivo ermittelt durch die Analyse naszierender Transkripte. Ein Großteil der plastidären RNA Spezies kopräzipitiert mit der PEP, aber sie scheint präferentiell mit tRNAs zu interagieren. Die Analyse der Verteilung der PEP bewies erstmals, dass sie hauptsächlich mit den Membranen assoziiert. Dort befindet sich auch das transkriptionsaktive Chromosom (TAC). Im TAC wurden vor kurzem neben der PEP auch Mitglieder von RNA Prozessierungsfaktoren identifiziert, was auf eine mögliche Kopplung von Transkription und posttranskriptionellen Prozessen hindeutet. Für einen Einblick in dieses Interaktionsnetzwerk wurden Transkriptanalysen des TACs ausgeführt. Mit wenigen Ausnahmen assoziieren alle plastidären RNA Spezies mit dem TAC. Einige RNAs liegen bereits prozessiert vor, was eine Verbindung zwischen Transkription und posttranskriptionellen Prozessen noch im TAC vermuten lässt. / Chloroplast transcription is astonishingly complex. The relative small genome of plastids, which codes for components of the photosynthetic machinery as well as for components of their own gene expression machinery, is transcribed by at least two different RNA polymerases. Beside the plastid-encoded plastid RNA polymerase (PEP) a nuclear-encoded plastid RNA polymerase (NEP) exists as well. PEP plays a major role in the expression of photosynthesis genes and is essential for chloroplast biogenesis and thus for plant survival. This work shows the specific in vivo interaction between PEP and its transcription units under different light conditions on a plastome-wide scale. Among them are DNA fragments that represent photosynthetic genes. In addition, PEP shows clear preferences to rRNA and tRNA genes. Furthermore, the association of PEP with photosynthesis-related genes was reduced during the dark period, indicating that PEP-DNA association is a light-dependent process. To survey PEP activity in vivo on plastid DNA regions, the association to nascent transcripts was analyzed. The majority of plastid RNA species could be found in PEP precipitates, but PEP seems to interact more strongly with tRNAs. Analysis of the suborganellar distribution of PEP shows that PEP is preferably associated with chloroplastmembranes. The transcriptionally active chromosome (TAC) was also found to be membrane-attached. Beside PEP different RNA processing factors were identified within the TAC and related purifications, indicating a possible coupling of transcription and posttranscriptional processes. To gain more insights into this interaction network, transcripts of TAC were analyzed. It is shown that nearly all plastid RNA species with only a few exceptions are associated to the TAC and that at least selected transcripts are already processed. This indicates that there is a link between transcription and posttranscriptional processes already within the TAC.
13

Photon efficient, high resolution, time resolved SPAD image sensors for fluorescence lifetime imaging microscopy

Parmesan, Luca January 2018 (has links)
FLIM is branch of microscopy mainly used in biology which is quickly improving thanks to a rapid enhancement of instrumentation and techniques enabled by new sensors. In FLIM, the most precise method of measuring fluorescent decays is called TCSPC. High voltage PMT detection devices together with costly and bulky optical setups which scan the sample are usually required in TCSPC instrumentation. SPADs have enabled a big improvement in TCSPC measurement setup, providing a CMOS compatible device which can be designed in wide arrays format. However, sensors providing in-pixel TCSPC do not scale in size and in large array like the time-gated SPAD pixel sensors do. Time-gated pixels offer a less precise lifetime estimation, discarding any photon information outside a given time window, but this loss in photon-efficiency is offset by gains in pixel size. This work is aimed at the development of a wide field TCSPC sensor with a pixel size and fill factor able to reduce the cost of such devices and to obtain a high resolution time-resolved fluorescence image in the shortest time possible. The study focuses on SPAD and pixel design required to maximise the fill factor in sub 10 μm pixel pitch. Multiple pixel designs are proposed in order to reduce pixel area and so enable affordable wide array TCSPC systems. The first proposed pixel performs the CMM lifetime estimation in order to reduce the frame rate needed to stream the data out of the SPAD array. This pixel is designed in a 10 μm pitch and attains with the most aggressive design a fill factor of 10:17 %. A second design proposes an analogue TCSPC which consists in a S/H TAC circuitry. This simpler pixel can achieve a higher fill factor of 19:63% as well as smaller pitch of 8 μm thanks to the adoption of SPAD n-well and electronics area sharing. This last design is implemented in a 320 x 256 SPAD array in which is included part of a novel ADC aimed at reduction of the processing time required to build a TCSPC histogram. A more conventional analogue readout is used to evaluate the pixel performance as well as a more fine TCSPC histogram. The device was used to measure the fluorescence lifetime of green micro-spheres while the 2b flash ADC is used to demonstrate rapid resolution and separation of two different fluorescence decays.
14

The ontology of communication: a reconcepualisation of the nature of communication through a critique of mass media public communication campaigns

Shrensky, Ruth, n/a January 1997 (has links)
Conclusion. It is probably now appropriate to close a chapter in the history of public communication campaigning. Weaknesses which have usually been seen as instrumental can now be seen for what they are: conceptual failures grounded in compromised ontologies and false epistemologies. As I showed in the last chapter, even when viewed within their own narrow empiricist frame, public communication campaigns fail to satisfy a test of empirical efficacy. But empirical failure reveals a deeper moral failure: the failure of government to properly engage in a conversation with the citizens to whom they are ultimately responsible. Whether public communication campaigns are a symptom or a cause of this failure lies beyond the scope of this thesis. But there can be little doubt that the practice of these campaigns has encouraged the persistence of an inappropriate relation between state and citizens. The originators and managers of mass media public communication campaigns conceive of and execute their creations as persuasive devices aimed at the targets who have been selected to receive their messages. But we do not see ourselves as targets (and there are profound ethical reasons why we should not be treated as such), neither do we engage with the mass media as message receivers. On the contrary, as social beings, we become actively and creatively involved with the communicative events which we attend to and participate in; the mass media, like all other communication opportunities, provide the means for generating new meanings, new ways of understanding, new social realities. But people are constrained from participating fully in public discussion about social issues; the government's construal of individuals as targets and of communication as transmitted messages does not provide the discursive space for mutual interaction. Governments should aim to encourage the active engagement of citizens in public discussion by conceiving of and executing public communication as part of a continuing conversation, not as packaged commodities to be marketed and consumed, or as messages to be received. It is time to encourage alternative practices-practices which open up the possibility of productive conversations which will help transform the relationship between citizens and state. However, as I have argued in this thesis, changed practices must be accompanied by profound changes in thinking, otherwise we continue to reinvent the past. Communication practice is informed by the ontology of communication which is itself embedded within other ontologies and epistemologies. The dominant paradigm of communication is at present in a state of crisis, caught between two views of communication power. On the one hand it displays an obsession with instrumental effectiveness on which it cannot deliver. On the other hand-in an attempt to discard the accumulated baggage of dualist philosophy and mechanistic models of effective communication-it indulges in a humourless critique of language which, as Robert Hughes astutely observes, is little more than an enclave of abstract complaint (Hughes 1993:72). This thesis has been an attempt to open up a space for a new ontology, within which we might create new possibilities.
15

Comportamiento cognitivo y afectivo en un grupo de pacientes con ictus no corticales

Gutiérrez Cabello, Luis 05 July 2007 (has links)
Entre un 25 y un 50% de los pacientes que sufren un infarto cerebral pueden desarrollar alteraciones cognitivas y una demencia en los tres meses posteriores. Las tecnologías del diagnóstico por imagen (TAC RM), han constituido un avance importante en la mejora del diagnóstico en los diferentes procesos patológicos. La presente tesis doctoral tiene como objetivo identificar las alteraciones neuropsicológicas, afectivas y cognitivo-conductuales que aparecen después de una lesión vascular cerebral, así como su evolución a los tres meses, en sujetos que no manifiestan lesiones corticales en la fase aguda del ictus.La muestra está compuesta por 74 pacientes con un ictus no cortical. También se analizan las correlaciones entre el volumen de la lesión (resonancia magnética, secuencias de DRM y FLAIR) y las puntuaciones en los test cognitivos, afectivos y un inventario cognitivo-conductual.RESULTADO: se lleva a cabo un análisis factorial exploratorio de componentes principales. Con un KMO de .782, se extraen siete componentes que explican un porcentaje acumulado de 72,54 de la varianza. Entre la evaluación en la fase aguda y la realizada tres meses después, no se observa una significativa mejoría en la memoria de aprendizaje y en la memoria diferida, aunque sí se verifica un mejoría en las otras pruebas cognitivas (función ejecutiva, denominación, atención, función visuoespacial y función psicomotora). Se observan puntuaciones estadísticamente significativas en los test cognitivos, afectivos y cognitivo-conductual cuando se comparan los pacientes con ictus recurrentes y no recurrentes, entre los diferentes grupos de edad y nivel educativo. En el inventario de obsesiones-compulsiones de Maudsley, se seleccionan dos grupos según sus puntuaciones (mayor o igual a 12) o (menor o igual a 13): los pacientes con puntuaciones menor o igual a 13 obtienen un significativo menor rendimiento en los siguientes test: examen cognitivo general (MMSE) p = ,001; escala de depresión (HRS-D) p: ,028; Dígitos WAIS p = ,037; memoria de aprendizaje (RAVLT) p: ,001; fluencia fonética p = ,002; fluencia semántica p = ,030; TMT (A y B) p = ,060; y p = ,010 respectivamente; test de procesos de denominación por confrontación visual (BNT) p = , 060; alternancias motoras (AM) p = ,015. En la Escala de Depresión de Hamilton, se seleccionan dos grupos según las puntuaciones en dicho test (6 y 7). Los pacientes con puntuaciones 7 obtienen un rendimiento significativamente menor en los test de cognición general (MMSE) p = ,004; Dígitos WAIS p =, 001; memoria de aprendizaje (RAVLT) p = ,001; fluencia fonética (FF) p = ,041; TMT-A p = ,013; test de denominación (BNT) p = , 022; funciones visuoespaciales (OLB) p = ,020; alternancias motoras (AM) p = , 031; y test de Cartas de Wisconsin (categorías) p = , 011.En el segundo estudio, se observan correlaciones estadísticamente significativas entre el volumen de la lesión (secuencia de DRM y FLAIR) con la fluencia fonética procesos de denominación (BNT), Test de cartas de Wisconsin. Cuando, además, utilizamos la lateralización de la lesión, se observa un rendimiento inferior en los test de denominación, TMT-B y WISCONSIN en el hemisferio izquierdo comparados con los del hemisferio derecho.CONCLUSIONES: la variable edad, nivel educativo y sexo afectan al rendimiento en la cognición de los pacientes con ictus. Sobretodo, la variable edad es un factor de mal pronóstico en el rendimiento en algunas pruebas cognitivas. No se observan diferencias por la lateralización de la lesión en la escala de Depresión de Hamilton ni en el Inventario MOCI, ni en la escala de Manía. Cuando se comparan las puntuaciones entre la fase aguda y su evaluación posterior a los tres meses, se observa una mejoría general en los resultados de los pacientes. Aunque estos no alcanzan un rendimiento parecido o igual al de los sujetos control. Las escalas de depresión de Hamilton y el inventario cognitivo -conductual MOCI afectan al rendimiento de la cognición (memoria de aprendizaje, fluencias verbales, función psicomotora). Además, se obtienen correlaciones estadísticamente significativas entre el volumen de la lesión, medido mediante secuencias DRM y FLAIR, y las puntuaciones en el test de denominación (BNT) y el test TMT-B. / "Cognitive and affective behaviour in a group of patients with non-cortical stroke" SUMMARY:Between 25 and 59% of patients with stroke may develop cognitive and degenerative impairment within three months. Affective and behavioural alterations may affect rehabilitation and recovery. Neuroimaging diagnostic techiques (CT, MRI) have significantly improved diagnosis of different pathological procesesses. DRM sequences allow us to visualise vascular lesions and compare lesion volumes with neuopsychological test scores. This thesis attempts to identify the neuropsychological, affective and cognitive-behavioural alterations appearing after cerebrovascular lesions and follows the evolution at three months in subjects not displaying cortical lesions in acute stroke. RESULTS AND CONCLUSION:Seventy-four cerebral stroke patients with a mean age of 60.32 years (SD 13.6). 25.7% of the patients were women. 73% of strokes were ischaemic and 27% were haemorrhagic. Also, a healthy control group of 20 volunteers was recruited. Exploratory factorial analysis of the principal components was performed. The Kaiser-Mayer-Olkin measure of sampling adequacy was .782. Seven components were extracted explain an accumulated percentage of variance of 72.54.No significant differences were observed in the side of the lesion. Significant differences were found in the semantic verbal fluency cognitive variable (p=.053). Patients with haemorrhagic lesions performed worse in this variable than patients with ischaemic lesions. Although there is an improvement in learning memory and long-term memory at three months, as compared to the acute phase, levels were still below the control group. Significant differences are observed in cognitive performance with regard to age, educational level, and sex. Cut-off points were established in the Hamilton Depression Scale and the MOCI Inventory: Statistically differences were observed in cognitive performance. Also, statistically significant differences were observed between the volume lesion and the Naming Test (BNT) and the TMT-B.
16

Horticulture production in conditions of Sub-Sahara Africa

Milanda, Johannes January 2014 (has links)
This paper was written to provide the literature review on the topic of horticultural production in Namibia or in neighboring countries, with a focus on vegetable species. To suggest a prospective representative vegetable species from the study area, which could have production potential in the Czech Republic. Four chosen cultivars (Metro, Nakare, Bira and Shidimba) from the Cowpea (Vigna uinguiculata L Walp) species were experimentally tested in conditions of the Czech Republic. They were grown naturally extensively with no fertilizers, herbicides or pesticides used. They're morphological parameters were then recorded and laboratory analyzed using ANOVA and three valuables [flavonoids, total antioxidants capacity (TAC) and polyphenols] were determined using different methods with the spectrophotometry.
17

Evaluating Agent Strategies for the TAC Supply Chain Management Competition / Evaluating Agent Strategies for the TAC Supply Chain Management Competition

Allblom, Viktor January 2004 (has links)
The TAC Supply Chain Management game was designed to capture many of the challenges involved in dynamic supply chain practices. To evaluate the game I created four different agents, which operate according to simple but very different strategies. In addition, an advanced agent was created to see if the game was advanced enough not to be dominated by simple strategies. While the game is advanced enough to resist simple strategies, it is so simplified that it will never help solve any real world problems unless it is expanded to include more factors/problems of supply chain management. / TAC Supply Chain Management spelet var designat för att fånga så många av utmaningarna inom dynamiska supply chains som möjligt. För att utvärdera spelet skapade jag fyra olika agenter, som har enkla beteenden men väldigt olika strategier. Utöver detta skapade jag också en avancerad agent för att se om spelet var avancerat nog att inte domineras av enkelspåriga strategier. Medans spelet är avancerat nog att stå emot enklare strategier, är det så förenklat att det aldrig kommer vara till någon hjälp för att lösa problem i den riktiga världen om det inte är utökat till att inkludera fler faktorer/problem inom supply chain management. / contact me at: pt00val@student.bth.se or viktor@allblom.info
18

An Agent-Based Approach for Automating the Process of Charging Plug-in Electric Vehicles

Civelek, Ülkan Fuat January 2010 (has links)
The study of Power TAC is a Multi-Agent competitive simulation test-bed, providing opportunity to simulate research and developments of electronic agents which can manage the tasks of the consumers and energy resources in a virtual energy infrastructure. According to the Power TAC scenario, Plug-in Electrical Vehicles are a special type of consumers that interact with this infrastructure and sometimes with the producers through aggregators. The aim of this study is modeling an intelligent Plug-in Electric vehicle agent for Power TAC that acts as an intermediary between Power TAC grid and vehicle owners. The proposed agent acts autonomously and is capable of making decisions about its energy needs by learning the driving behaviors and other preferences of these vehicle owners in a specified time interval. These agents will be able to make decisions about buying energy from the grid when the charging process is necessary or sell their energy back to the grid when the conditions of the electricity market are sufficiently attractive. The objective of this study is to model a Multi-Agent system for automating the process of charging the plug-in Vehicle Agents in Power TAC scenario by determining the necessary agents and the simulation environment where the agents constructed and simulated. Аs results of this study, different strategies are defined by considering the preferences of the vehicle owners and the conditions of the vehicle; thereby the agents autonomously bid behalf of their user in order to automate the process of charging.
19

Adversarial Game Playing Using Monte Carlo Tree Search

Sista, Subrahmanya Srivathsava January 2016 (has links)
No description available.
20

Från Vetenskap till Politik : EU:s TAC-Beslut och Fiskbeståndens Framtid / From science to politics: : EU TAC decisions and the future of fish stocks

Hägglöf, Filip January 2024 (has links)
Overfishing is a global issue that threatens marine ecosystems and economies dependent on fish resources. This thesis analyzes how the EU:s Total Allowable Catches (TAC) system affects the utilization and sustainability of fish stocks. By applying the theory of the tragedy of the commons, the decision-making process regarding TAC and the political factors influencing these decisions are examined. The study reveals that political considerations often lead to TAC levels being set higher than the scientific recommendations issued by ICES, exacerbating the problem of overfishing. The anlysis also identifies where the EU:s TAC system has failed or succeeded in promoting sustainable fishing. The findings indicate that to avoid the tragedy of the commons, more transparent and scientifically grounded decisions are needed, along with effective measures to reduce overcapacity in fishing fleets. This thesis contributes to a deeper understanding of the complexities in fisheries policy and the need for sustainable solutions to preserve marine resources.

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