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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.
61

Data acquisition and real-time signal processing in Positron Emission Tomography

Lamwertz, Leonid 23 August 2013 (has links)
OpenPET was developed to be a scalable and flexible design for data acquisition and signal processing in Positron Emission Tomography (PET) systems. The OpenPET hardware design is mature, but the control software and firmware need further development. In this thesis we developed a software application to connect a host PC with an OpenPET system. We also developed data acquisition firmware that allows data transfer to the host PC. A novel design for an OpenPET coincidence detection processor was proposed, with its basic functionality implemented and validated. A novel method to process PET events in real time was also introduced and validated using simulated data. The feasibility of implementation of this method using Field Programmable Gate Arrays (FPGAs) was demonstrated for our OpenPET system.
62

Methods To evaluate the effectiveness of certain surrogate measures to assess safety of opposing left-turn interactions

Peesapati, Lakshmi Narasimham 27 August 2014 (has links)
Highway safety evaluation has traditionally been performed using crash data. However crash data based safety analysis has limitations in terms of timeliness and efficiency. Previous studies show that the use of surrogate safety data allows for earlier evaluation of safety in comparison to the significantly longer time horizon required for collecting crash data. However, the predictive capability of surrogate measures is an area of ongoing research. Previous studies have often resulted in inconsistent findings in the relationship between surrogates and crashes, one of the primary reasons being inconsistent definitions of a conflict. This study evaluated the effectiveness of certain surrogate measures (Acceleration-Deceleration profile, intersection entering speed of through vehicles, and Post Encroachment Time (PET)) in assessing the safety of opposing left-turn interactions at 4-legged signalized intersections by collection of time resolved video from eighteen selected intersections throughout Georgia. Overall, this research demonstrated that surrogate measures can be effective in safety evaluation, specifically demonstrating the use of PET as a surrogate for crashes between left-turning vehicles and opposing through vehicles. The analysis of data found that the selected surrogate threshold is critical to the effectiveness of any surrogate measure. For example, the required PET threshold was found to be as low as 1 second to identify high crash intersections, significantly lower than the commonly reported 3 second threshold. Non-parametric rank analysis methods and generalized linear modeling techniques were used to model PET with other intersection and traffic characteristics to demonstrate the degree to which these surrogates can be used to identify potential high-crash intersections without resorting to a crash history. Finally, the effectiveness of PET and its assistance to decision makers is also been demonstrated through an example that helped find errors in reported crash data.
63

Data acquisition and real-time signal processing in Positron Emission Tomography

Lamwertz, Leonid 23 August 2013 (has links)
OpenPET was developed to be a scalable and flexible design for data acquisition and signal processing in Positron Emission Tomography (PET) systems. The OpenPET hardware design is mature, but the control software and firmware need further development. In this thesis we developed a software application to connect a host PC with an OpenPET system. We also developed data acquisition firmware that allows data transfer to the host PC. A novel design for an OpenPET coincidence detection processor was proposed, with its basic functionality implemented and validated. A novel method to process PET events in real time was also introduced and validated using simulated data. The feasibility of implementation of this method using Field Programmable Gate Arrays (FPGAs) was demonstrated for our OpenPET system.
64

A slow control system with gain stabilization for a small animal MR-compatible PET insert

Shams, Ehsan 22 December 2014 (has links)
The Biomedical Imaging Lab at the University of Manitoba is building an MR compatible PET insert system. The detectors include SensL SPM ArraySB-4 SiPMs and dual layer offset LYSO crystal blocks with 409 total crystals. The detectors’ gain varies with temperature and bias voltage. Measurements inside the MR magnet revealed that the equilibrium temperature was around 30°C. The photopeak amplitude, energy resolution and events per crystal were studied at 30°C and also at temperatures from 20°C to 40°C with a fixed overvoltage of 2.5V and with a fixed bias voltage of 27.95V. It was determined that a fixed overvoltage helps stabilize detector output but is not sufficient. A study of detector characteristics versus overvoltage was subsequently conducted and a lookup table was constructed to adjust bias voltage. A distributed network-based control system was developed in this thesis project to monitor the operating parameters of the detectors.
65

Synthesis and Preliminary Evaluation of an F-18 Labeled Fluoropyridine Losartan Analog as a Novel PET Tracer for Imaging AT1 Receptors

Arksey, Natasha C. 30 April 2012 (has links)
Several cardiac diseases, including hypertrophy, cardiomyopathy, and myocardial infarction, result in the upregulation of cardiac angiotensin II type-1 receptors (AT1R). Imaging the AT1R in vivo via PET provides the potential to monitor disease progression and guide therapy accordingly. The aim of this research was to develop a novel F-18 labeled losartan analog as an AT1R PET tracer and begin evaluation in rats. Due to the longer half-life and shorter positron range of F-18, we presume that an F-18 labeled tracer will be more beneficial than current C-11 labeled tracers. Prior structure-activity relationship (SAR) studies suggested the addition of substituents to the hydroxyl group of losartan would minimally affect AT1R binding affinity. [18F]Fluoropyridine losartan ([18F]FPyrLos) was synthesized in an automated module through conjugation of [18F]fluoro-3-pent-4-yn-1-yloxypyridine ([18F]FPyKYNE) to azide-modified losartan via the Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) ‘click’ reaction. [18F]FPyrLos was produced in approximately 10% yield (decay-corrected) with > 97.5% purity and specific activities up to 4,200 mCi/µmol. MicroPET (Siemens Inveon) images of normal Sprague Dawley rats displayed high uptake in the kidneys (ratio of 8.3 compared to surrounding tissue at 10 min). Metabolite analysis in the kidneys and plasma by column-switch HPLC revealed that roughly two-thirds of the tracer was unchanged 10 min post-injection and that one labeled hydrophilic metabolite exists, accounting for roughly 6% of the total activity. Both microPET and metabolism studies displayed a dose-dependent reduction in renal uptake upon co-injection with AT1R blocker candesartan indicating specific binding. Further work in rat disease models is required to evaluate the potential of this tracer for imaging cardiac AT1R.
66

Estudo do impacto da viscosidade intrínseca do pet reciclado pós-consumo em embalagens cosméticas

Castro, Paula Junqueira de 14 August 2015 (has links)
Made available in DSpace on 2016-03-15T19:36:55Z (GMT). No. of bitstreams: 1 Paula Junqueira de Castro.pdf: 2618815 bytes, checksum: 92b10379ab9b859ea52e163bf40779ee (MD5) Previous issue date: 2015-08-14 / The use of PET in cosmetics packaging is growing and the use of post-consumer recycled material is an alternative with the development of recycling process and also with all the discussions about the increase of environmental impact. The objective of this project is to evaluate the influence of post-consumer recycled PET in the mechanical properties and the aesthetics appearance in cosmetics packaging. The materials used was virgin PET with nominal value of intrinsic viscosity (IV) of 0,80 dL/g and two grades of post-consumer recycled PET with nominal value of IV of 0,68dL/g and 0,80dL/g. The main parameter used in the PET industry is the IV because it is directly related to the molar mass of the polymer and also to the quality of the material. The packages were manufactured by injection stretch blow molding process with different percentages of virgin PET and post-consumer recycled PET. The characterization was realized by visual analysis, spectroscopy to evaluate the variation of color and mechanical tests. The results were satisfactory for the mechanical tests, showing no major differences in results when compared to virgin PET. In aesthetics appearance, the color variation is noticeable, due to the thermal degradation of the material, but less noticeable in the packages with the post-consumer recycled PET with lower IV. / A utilização de embalagens de PET na indústria de cosméticos é ampla e crescente, a incorporação de material reciclado pós-consumo passa a ser uma alternativa com o avanço da tecnologia da reciclagem mecânica do PET e do aumento da discussão de impacto ambiental. O objetivo principal do trabalho é avaliar a influencia na estética e na resistência mecânica do PET reciclado pós-consumo em embalagens de cosméticos com diferentes composições e valores de viscosidade intrínseca (VI). Utilizou-se PET virgem com valor nominal de VI 0,80 dL/g, PET reciclado pós-consumo com valor nominal de VI de 0,68dL/g e 0,80dL/. A VI é a medida mais difundida na indústria do PET, um importante parâmetro de qualidade do material, relacionado diretamente com a massa molar do mesmo. As embalagens foram produzidas através do processo de injeção-sopro com diferentes porcentagens de PET virgem e PET reciclado pós-consumo. A caracterização foi realizada através de analise visual, espectroscopia para avaliação da variação da cor e ensaios mecânicos. Os resultados foram satisfatórios para os ensaios mecânicos, não apresentando diferenças significativas dos resultados quando comparado ao PET virgem. Na questão estética, a variação de cor é bastante perceptível, decorrente da degradação termo-oxidativa do material, porém menos aparente para o PET reciclado pós-consumo com menor valor de VI.
67

Remoção de corante de poli(tereftalato de etileno) (PET) através de recristalização e sua posterior despolimerização em meio ácido / Removing dye from poly(ethylene terephthalate) (PET) by recrystallization and its subsequent depolymerization in acid medium

Stefanelli, Talita Katiuska Takizawa Dias, 1983- 23 August 2018 (has links)
Orientadores: Maria Regina Wolf Maciel, Glaucia Maria Ferreira Pinto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T20:46:02Z (GMT). No. of bitstreams: 1 Stefanelli_TalitaKatiuskaTakizawaDias_M.pdf: 1571611 bytes, checksum: 5c787cef4fc94a299d2b85a0e62656e1 (MD5) Previous issue date: 2013 / Resumo: O consumo de polímeros sintéticos no Brasil e no mundo vem aumentando há décadas, numa clara demonstração do enorme sucesso conseguido por esses materiais nas mais variadas aplicações. As características típicas dos polímeros sintéticos, como seu custo praticamente irrisório, baixo peso, boa resistência mecânica, impermeabilidade, transparência e capacidade de coloração mais impressão lhe conferiram trunfos irresistíveis para seu uso massivo na forma de embalagens, uma aplicação extremamente importante numa sociedade voltada para o consumo. O grande problema dos polímeros sintéticos reside na sua curta vida útil, o que conduz a um rápido aumento da corrente de resíduos, como é o caso das embalagens. Dentro desse âmbito, a reciclagem passa ser uma alternativa promissora. Por definição, a reciclagem é um processo de transformação dos materiais previamente separados para posterior utilização; é a recuperação de resíduos mediante uma série de operações que permitem que materiais processados sejam aproveitados como matéria-prima no processo gerador ou em outros. A primeira etapa deste trabalho foi a tentativa de fazer a despolimerização de PET utilizando o processo de destilação molecular. Os resultados mostraram que não é possível utilizar o destilador molecular na despolimerização do PET. Na segunda etapa deste trabalho o pet pósconsumo foi submetido à recristalização para remoção do corante, utilizando ácido trifluoracético como solvente, na tentativa de uma nova alternativa de reciclagem para este material. O material modificado e o PET pós-consumo foram caracterizados por termogravimetria (TG) e calorimetria exploratória diferencial (DSC) / Abstract: The use of synthetic polymers in the world and particularly in Brazil has been increasing for decades representing the huge success achieved by these materials in various applications. The main characteristics of synthetic polymers are their low cost and weight, good mechanical strength, impermeability, transparency and the possibility of coloring, which results in their massive use in the form of packaging an application extremely important in a society focused on consumption. Despite all its advantages, the polymers are generally used in the manufacture of objects whose useful life it is extremely short, like bottled water and soft drinks , produced with polyethylene terephthalate (PET), or as previously mentioned, in packs of all species, resulting in a rapid increase in the waste stream. In this scenario, recycling becomes a promising alternative. By definition, recycling is a process of transformation materials previously separated for later use or is the recovery of waste by means of a series of operations that allow processed materials to be utilized as raw material in generating process or in other process. The first stage of this work was to attempt to make the depolymerization of PET using molecular distillation process, but results showed that it is not possible to use the molecular distiller for the depolymerization of this type of polymer. In the second stage of the work, post-consumer PET was subjected to recrystallization to remove the dye, using trifluoroacetic acid as solvent in in a new attempt to recycle this material. The modified material and post-consumer PET were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química
68

Synthesis and Preliminary Evaluation of an F-18 Labeled Fluoropyridine Losartan Analog as a Novel PET Tracer for Imaging AT1 Receptors

Arksey, Natasha C. January 2012 (has links)
Several cardiac diseases, including hypertrophy, cardiomyopathy, and myocardial infarction, result in the upregulation of cardiac angiotensin II type-1 receptors (AT1R). Imaging the AT1R in vivo via PET provides the potential to monitor disease progression and guide therapy accordingly. The aim of this research was to develop a novel F-18 labeled losartan analog as an AT1R PET tracer and begin evaluation in rats. Due to the longer half-life and shorter positron range of F-18, we presume that an F-18 labeled tracer will be more beneficial than current C-11 labeled tracers. Prior structure-activity relationship (SAR) studies suggested the addition of substituents to the hydroxyl group of losartan would minimally affect AT1R binding affinity. [18F]Fluoropyridine losartan ([18F]FPyrLos) was synthesized in an automated module through conjugation of [18F]fluoro-3-pent-4-yn-1-yloxypyridine ([18F]FPyKYNE) to azide-modified losartan via the Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) ‘click’ reaction. [18F]FPyrLos was produced in approximately 10% yield (decay-corrected) with > 97.5% purity and specific activities up to 4,200 mCi/µmol. MicroPET (Siemens Inveon) images of normal Sprague Dawley rats displayed high uptake in the kidneys (ratio of 8.3 compared to surrounding tissue at 10 min). Metabolite analysis in the kidneys and plasma by column-switch HPLC revealed that roughly two-thirds of the tracer was unchanged 10 min post-injection and that one labeled hydrophilic metabolite exists, accounting for roughly 6% of the total activity. Both microPET and metabolism studies displayed a dose-dependent reduction in renal uptake upon co-injection with AT1R blocker candesartan indicating specific binding. Further work in rat disease models is required to evaluate the potential of this tracer for imaging cardiac AT1R.
69

Caractérisation d'un biomarqueur pour l'étude en tomographie par émission de positons des récepteurs muscariniques de type M2 pour le diagnostic précoce de la maladie d'Alzheimer / Characterization of a potential in vivo biomarker for Alzheimer's Disease

Ravasi, Laura 19 September 2011 (has links)
La maladie d'Alzheimer (MA) a un impact socio-économique majeur. Le diagnostic n’est certain qu’à l'autopsie. Il n’existe pas de biomarqueur assurant un diagnostic précoce in vivo. Les quatre traitements actuellement disponibles sont symptomatiques. Les autres traitements qui ont fait l’objet d’essais de recherche clinique, n’ont pas démontré de modification de l’évolution de la maladie. Les hypothèses sous-jacentes à cet échec sont soit l’inefficacité du traitement, soit un manque d'homogénéité de la population étudiée (diagnostic différentiel parfois très compliqué), soit l’absence de biomarqueurs fiables in vivo en mesure de détecter une modification. Dans ce contexte, il est essentiel d'identifier un biomarqueur in vivo qui permette d’établir le diagnostic différentiel entre la MA et les autres démences et d’évaluer l'efficacité des traitements. Ce travail vise à caractériser in vitro, ex vivo et in vivo le 3 - (3 - (3-fluoropropylthio) -1,2,5-thiadiazole-4-yl) -1,2,5,6-tétrahydro-1-méthylpyridine [FP-TZTP], chez les rongeurs pour évaluer son intérêt en tant que biomarqueur potentiel pour la maladie d'Alzheimer. Après avoir établi que l’expression du sous type M2 des récepteurs muscariniques était modifiée précocement dans la MA, nous avons mis en évidence une distribution du radiotraceur fluoré FP-TZTP spécifique de M2 chez la souris génétiquement modifiée ‘knock out’. Afin de mieux caractériser ce radiotraceur, nous avons effectué des études de culture cellulaire in vitro ainsi que des études ex-vivo sur du tissu cérébral pour comprendre la spécificité du [18F]FP-TZTP (Résultats #1). Les résultats ex-vivo nous ont encouragés à réaliser les études in vivo. Nous avons choisi la tomographie par émission de positons (TEP) qui permet l’étude in vivo et non invasive de la biodistribution du [18F]FP-TZTP chez le rat, en utilisant le scanner pour animaux de petite taille (ATLAS) développé par « The National Institutes of Health , Bethesda, MD, USA» (Résultats #4). Pour cela, nous avons dans un premier temps testé l'ATLAS au moyen de deux études métaboliques chez le rat, avec un traceur couramment utilisé, le [18F]fluorodéoxyglucose ([18F]FDG) (Résultats #2; Résultats #3). Nos études suggèrent que le [18F]FP-TZTP est un traceur approprié pour la quantification en TEP des récepteurs muscariniques de type M2, utile pour le diagnostic précoce de la MA. / Alzheimer’s disease (AD) has an increasingly critical impact on society from the socio-economic point of view in addition to being very burdensome for the patients themselves, their relatives and friends. Diagnosis of certitude is only at post mortem and no single biomarker has yet been found to be accurate for early in vivo diagnosis. The current available treatments are only symptomatic. The few treatments under research trials have failed to demonstrate a disease modification for either lack of actual treatment efficacy or for lack of population homogeneity and for lack of reliable in vivo biomarkers able to detect a modification. In this context, it is both urgent and necessary to identify an in vivo biomarker that enables i) the differential diagnosis of AD among other dementias and ii) the assessment of treatment efficacy as a follow up in AD patients, is clearly very noticeable. This work aims to characterize the 3-(3-(3-fluoropropylthio)-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine [FP-TZTP], by use of in vitro, ex–vivo and in vivo methods in rodents, to assess whether it is a suitable biomarker for Alzheimer’s disease. An impairment of the M2 subtype of the muscarinic receptors was noticed in AD patients and clear evidences of M2 selectivity in knock out mice previously injected with the fluorinated radiotracer FP-TZTP was observed. To further characterize such M2 selectivity, we performed in vitro cell culture and ex-vivo tissue dipping studies (Results #1). Encouraged by the ex-vivo results, we went on to the in vivo world. We elected the non-invasive nuclear medicine imaging technique Positron Emission Tomography (PET) to assess the biodistribution of the [18F]FP-TZTP in rats by use of the Advanced Technology Laboratory Animal Scanner (ATLAS) developed at the National Institutes of Health, Bethesda, MD, USA (Results #4). We had first assessed the ATLAS as a legitimate tool by use of a commonly used and well known radiotracer, the [18F]fluorodeoxyglucose ([18F]FDG) (Results #2 and #3). Our studies suggest that [18F]FP-TZTP may be a biomarker for AD as it is a suitable tracer for in vivo quantification of the M2 receptors.
70

Servicio integral y supermercado para mascotas Villa House Pet Center

Céspedes, Javier, Chumpitaz, Yanina, Saettone, Renzo 04 1900 (has links)
El objetivo del desarrollo de este plan de marketing, es establecer los lineamientos y estrategias que permitan un adecuado desarrollo de la marca Villa House Pet Center como negocio, teniendo entre los principales pilares de un correcto posicionamiento, los elementos que conforman la identidad de la marca y el plan de comunicaciones, apoyado en el protocolo de servicios, los paquetes de membresías anuales personalizados y el acertado seguimiento de las necesidades de las mascotas registradas. Se destacan fortalezas de la empresa, como la experiencia en el rubro de mascotas, el manejo de personal, el servicio personalizado ofrecido; como ventajas, la ubicación estratégica, que une a los cuatro distritos de Lima que tienen con mayor cantidad de hogares con mascotas. Pero también es importante considerar que somos nuevos en la zona y que debemos usar todas las herramientas disponibles para generar tráfico de público, en particular al inicio, mientras nos hacemos conocidos y valorados. A través de la investigación de mercado, el análisis de fuentes secundarias y la identificación del segmento target, se han definido las dimensiones o lugares donde los dueños de mascotas pasan mayor tiempo, y los puntos de contacto o medios donde pueden ser impactados, estableciendo un plan de comunicaciones acorde al objetivo y al presupuesto, el cual direccionará su mayor esfuerzo en el tema digital, el boca a boca y publicity; en este último se debe destacar no solo la promesa de valor, sino lo más importante, la ventaja diferencial, que se dará con el protocolo de atención y las membresías.

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