Elevated sympathetic nervous system (SNS) tone contributes to excess cardiac mortality associated with type 2 diabetes mellitus (T2DM). Chronic SNS stimulation has detrimental effects to the heart, in particular, with its cell signaling abilities. (R)-[11C]Rolipram small animal positron emission tomography (PET), an noninvasive nuclear imaging modality, was used to assess phosphodiesterase-4 (PDE4) alterations in a high fat diet (HFD), streptozotocin (STZ) induced model of hyperglycemia in rats. Prior to investigation in the animal model, characterization of (R)-[11C]rolipram small animal PET was completed. (R)-[11C]Rolipram binds specifically to PDE4 in the rat heart demonstrated by competitive blockade with (R)-rolipram with the PDE4 enzyme susceptible to saturation with increasing injected masses of unlabeled rolipram. (R)-[11C]Rolipram cardiac retention was elevated by acute norepinephrine stimulation via desipramine pharmacologic challenge. Quantitative (R)-[11C]rolipram PET was highly reproducible in the heart and presents an ideal avenue to investigate PDE4 alterations. (R)-[11C]rolipram small animal PET did not reveal changes in PDE4 expression and activity in STZ-treated hyperglycemic animals compared to STZ-treated euglycemic and control groups. In vitro measures of PDE4 enzyme expression and activity, with or without desipramine, were also not altered between treatment groups. Although (R)-[11C]rolipram small animal PET does not reveal PDE4 alterations in this animal model of diabetes, its utility to assess PDE4 alterations in other over active SNS pathologies, such as heart failure and obesity, remains.

Nanocomposites are a new class of mineral-field plastics that contain relatively small amounts (&lt / 10%) of nanometer-sized clay particles. The particles, due to their extremely high aspect ratios (about 100-15000), and high surface area (in excess of 750-800 m2/g) promise to improve structural, mechanical, flame retardant, thermal and barrier properties without substantially increasing the density or reducing the light transmission properties of the base polymer. Production of thermoplastic based nanocomposites involves melt mixing the base polymer and layered silicate powders that have been modified with hydroxyl terminated quaternary ammonium salt. During mixing, polymer chains diffuse from the bulk polymer into the van der Waals galleries between the silicate layers. In this study, new nanocomposite materials were produced from the components of recycled thermoplastic as the matrix and montmorillonite as the filler by using a co-rotating twin screw extruder. During the study, recycled poly(ethylene terepthalate), R-PET, was mixed with organically modified quaternary alkylammonium montmorillonite in the contents of 1, 2, and 5 weight %. Three types of clays were evaluated during the studies. For comparison, 2 weight % clay containing samples were prepared with three different clay types, Cloisite 15A, 25A, 30B. The nanocomposites were prepared at three different screw speeds, 150, 350, 500 rpm, in order to observe the property changes with the screw speed. Mechanical tests, scanning electron microscopy and melt flow index measurements were used to characterize the nanocomposites. The clay type of 25A having long alkyl sidegroups gave the best results in general. Owing to its branched nature, in nanocomposites with 25A mixing characteristics were enhanced leading to better dispersion of clay platelets. This effect was observed in the SEM micrographs as higher degrees of clay exfoliation. Nearly all the mechanical properties were found to increase with the processing speed of 350 rpm. In the studies, it was seen that the highest processing speed of 500 rpm does not give the material performance enhancements due to higher shear intensity which causes defect points in the structure. Also the residence time is smaller at high screw speeds, thus there is not enough time for exfoliation. In general, the MFI values showed minimum, thus the viscosity showed a maximum at the intermediate speed of 350 rpm. At this processing speed, maximum exfoliation took place giving rise to maximum viscosity. Also, the clay type of 25A produced the lowest MFI value at this speed, indicating the highest degree of exfoliation, highest viscosity, and best mechanical properties.

Elevated sympathetic nervous system (SNS) tone contributes to excess cardiac mortality associated with type 2 diabetes mellitus (T2DM). Chronic SNS stimulation has detrimental effects to the heart, in particular, with its cell signaling abilities. (R)-[11C]Rolipram small animal positron emission tomography (PET), an noninvasive nuclear imaging modality, was used to assess phosphodiesterase-4 (PDE4) alterations in a high fat diet (HFD), streptozotocin (STZ) induced model of hyperglycemia in rats. Prior to investigation in the animal model, characterization of (R)-[11C]rolipram small animal PET was completed. (R)-[11C]Rolipram binds specifically to PDE4 in the rat heart demonstrated by competitive blockade with (R)-rolipram with the PDE4 enzyme susceptible to saturation with increasing injected masses of unlabeled rolipram. (R)-[11C]Rolipram cardiac retention was elevated by acute norepinephrine stimulation via desipramine pharmacologic challenge. Quantitative (R)-[11C]rolipram PET was highly reproducible in the heart and presents an ideal avenue to investigate PDE4 alterations. (R)-[11C]rolipram small animal PET did not reveal changes in PDE4 expression and activity in STZ-treated hyperglycemic animals compared to STZ-treated euglycemic and control groups. In vitro measures of PDE4 enzyme expression and activity, with or without desipramine, were also not altered between treatment groups. Although (R)-[11C]rolipram small animal PET does not reveal PDE4 alterations in this animal model of diabetes, its utility to assess PDE4 alterations in other over active SNS pathologies, such as heart failure and obesity, remains.

Small animal positron emission tomography (PET) image analysis can be particularly challenging with heavily-lesioned animal disease models with limited tracer uptake such as the 6-hydroxydopamine (OHDA) lesioned rat model of Parkinson's disease. Methodology-related variations in measured values of 10% or 15% can obscure meaningful biological differences, so accurate analysis methods are essential. However, placing regions of interest (ROIs) on these images without additional guidance is unreliable, and can lead to significant errors in results. To address this problem, this work develops a partly atlas-guided method place ROIs on structures that lack specific binding with presynaptic dopaminergic tracers. The method is tested by correlation of PET binding potential (BP) with autoradiographic binding measurements, and with repeated PET scans of the same subjects, both with the presynaptic tracer ¹¹C-dihydrotetrabenazine (DTBZ). The method is found to produce reliable results. When directly comparing PET images of the same subject to detect changes, it is essential to minimize variations due to analysis method. To this end, a masking method for automated image registration (AIR) of PET images with dopaminergic tracer rat images is developed. Coregistration with AIR and separate ROI placement are compared and tested with repeated scans of the same rat with DTBZ, and are found to be equivalent. Kinetic modelling algorithms may also introduce bias or scatter to binding potentials (BP) calculated from TACs or in parametric images. To determine the optimal method for this step, algorithms for dopaminergic tracers are compared for small animal DTBZ, ¹¹C-methylphenidate (MP), and ¹¹C-raclopride (Rac) data. Among the tested methods is a new variant of the Logan graphical kinetic modelling method, developed in this work, that issignificantly less biased by target tissue TAC noise than the standard Logan approach. The modified graphical method is further compared with the Logan graphical algorithms with added-noise simulations. The simplified reference tissue model (SRTM) is found to have the best method for ROI TAC data, while the modified graphical algorithm may be preferred when generating parametric images.

En els darrers anys ha augmentat de manera considerable l'interès de les empreses per l'ús de materials reciclats per a la fabricació dels seus productes. Les raons principals són l'estalvi econòmic que comporta a causa del progressiu increment del preu de la matèria primera i l'aposta per una política ambiental d'empresa, com a part de la seva responsabilitat social corporativa, en sintonia amb una sensibilitat creixent en l'opinió pública.Aquesta tesi s'ha centrat en l'estudi de la viabilitat de la utilització de materials termoplàstics reciclats per a aplicacions en el sector de l'electrònica de consum. En una primera part, s'ha estudiat la viabilitat de la substitució dels materials verges poliestirè antixoc (HIPS) i la mescla de polímers poli(èter de fenilè) amb poliestirè antixoc (PPE/HIPS) pels mateixos materials d'origen reciclat, procedents de residus industrials. En una segona part, s'ha estudiat la viabilitat de substitució dels mateixos materials verges, estudiats en la primera part, per un material reciclat diferent. Aquest material reciclat ha estat el poli(tereftalat d'etilè)(PET) provinent de la recollida selectiva d'envasos de begudes postconsum. El treball de recerca ha estudiat la variació de propietats mecàniques i tèrmiques dels materials reciclats de partida i de les mescles de material verge i reciclat, els efectes de la degradació provocats pels processos successius de transformació i la influència de càrregues minerals (fibres i microesferes de vidre) i ignifugants a base de fòsfor lliures d'halògens sobre les propietats dels materials. L'estudi realitzat sobre aquests tres materials reciclats ha permès analitzar els factors que intervenen en l'estudi de materials reciclats, conèixer-ne les possibilitats d'aplicació en el cas concret de components d'electrònica de consum i crear les bases per poder establir una metodologia per realitzar futurs estudis d'introducció de materials reciclats en altres aplicacions tecnològiques. / En los últimos años ha aumentado de manera considerable el interés de las empresas por el uso de materiales reciclados para la fabricación de sus productos. Las razones principales son el ahorro económico que conlleva a causa del progresivo incremento del precio de la materia prima y la apuesta por una política medioambiental de empresa, como parte de su responsabililidad social corporativa, en sintonía con una sensibilidad creciente en la opinión pública.Esta tesis se ha centrado en el estudio de la viabilidad de la utilización de materiales termoplásticos reciclados para aplicaciones en el sector de la electrónica de consumo. En una primera parte, se ha estudiado la viabilidad de la sustitución de los materiales vírgenes poliestireno antichoque (HIPS) y la mezcla de polímeros poli(éter de fenileno) con poliestireno antichoque (PPE/HIPS) por los mismos materiales de origen reciclado, procedentes de residuos industriales. En una segunda parte, se ha estudiado la viabilidad de sustitución de los mismos materiales vírgenes, estudiados en la primera parte, por un material reciclado diferente. Este material reciclado ha sido el poli(tereftalato de etileno) (PET) procedente de la recogida selectiva de envases de bebidas postconsumo.El trabajo de investigación ha estudiado la variación de propiedades mecánicas y térmicas de los materiales reciclados de partida y de las mezclas de material virgen y reciclado, los efectos de la degradación provocados por los procesos sucesivos de transformación y la influencia de cargas minerales (fibras y microesferas de vidrio) y ignifugantes a base de fósforo libres de halógenos sobre las propiedades de los materiales.El estudio realizado sobre estos tres materiales reciclados ha permitido analizar los factores que intervienen en el estudio de materiales reciclados, conocer las posibilidades de su aplicación en el caso concreto de componentes de electrónica de consumo y crear las bases para poder establecer una metodología para realizar futuros estudios de introducción de materiales reciclados en otras aplicaciones tecnológicas. / In recent years the interest of companies in the use of recycled materials for the manufacture of their products has increased considerably. The main reasons for this are, firstly, the economic savings offered when compared to the progressive increase in the price of the raw material and secondly, the pressure for a company to implement an environmental policy, as part of its 'corporate social responsibility', in tune with a growing sensitivity of public opinion in this area. This thesis has focussed on studying the feasibility of the use of recycled thermoplastic materials for applications in the consumer electronics sector. In the first part, it centres on the feasibility of the substitution of the virgin materials High-Impact Polystyrene (HIPS) and the mix of polymers poly(ether phenylene) with High-Impact Polystyrene (PPE/HIPS), for the same materials of recycled origin, coming from industrial waste. In the second part, it studies the feasibility of substitution of the virgin materials studied in the first part, by a different recycled material. This recycled material being the pol (ethylene terephtalat) (PET) which comes from the selective collection of post consumption drink bottles. The research work has studied the variation of mechanical and thermal properties of the original recycled materials and of the mixtures of virgin and recycled material, the effects of the degradation provoked by the successive transformation processes and the influence of mineral fillers (fibres and glass beads) and halogen-free phosphor-based flame retardants, on the properties of the materials. The study, carried out on these three recycled materials, has allowed the following: analysis of the factors that intervene in the investigation of recycled materials; knowledge regarding the possibilities of application in the case of household electronics components and it has created the bases for being able to establish a methodology for carrying out future studies on the introduction of recycled materials in other technological applications.

Positron Emission Tomography (PET) plays a very important role in the field of drugdevelopment already in the preclinical phase. This is done by using positron labeled molecules for different approaches/methodologies such as cell analysis, frozen section autoradiography, homogenate binding, organ distribution and at the end in vivo small-animal PET imaging. The technique is also used for integrated animal studies in which both functional information from PET or Single Photon Emission Tomography (SPECT) and structural information from Computed Tomography (CT) are integrated. However, significant improvements in technical aspects of the animal scanner such as resolution (under 1 mm), high sensitivity and ease of the operational procedures have affected the usage of these types of imaging. This study aims to test the technical and operational performance of the FLEX Triumph preclinical PET/SPECT/CT imaging system. Spatial resolution, sensitivity and partial volume effects have been the parameters in focus but a performance comparison between different isotopes and an in vivo mouse study has also been performed. The results show that the Triumph is capable of producing high quality images for all modalities and also high quality PET/CT fusions.

This research is focus on the entrepreneurial experiences of new pet-related businesses enterprisers, and tries to investigate the characters of new pet-related businesses, the connections between life experiences and process of entrepreneurship, and the roles pets play in the process of entrepreneurship through a phenomenological approach. The research findings are¡G 1. The valued services provided for customers and pet owners by new pet-related businesses are invisible. They can realize the personificational imagination about pets, give customers the mental comfort, and raise the possibility of developing interpersonal interaction. Therefore, new pet-related businesses emphasize spiritual consumption and making customers happy and content is the core value of new pet-related businesses. 2. The life experiences of new pet-related businesses enterprisers give them the opportunities of starting their own businesses. The connections between life experiences and the process of entrepreneurship are shown by two essences. One is the pursuance of autonomy, and the other is the protection of animal life. Due to the experiences, new pet-related businesses enterprisers may have unique and non-business oriented values of their business. 3. The most important factors in new pet-related businesses, pets, play the dynamic roles in the process of entrepreneurship. They can have multiple meanings simultaneously for new pet-related businesses enterprisers, and may change their roles according to different enterprisers and situations they are in.

A telephone questionnaire was developed to collect information on pet owners, cat ownership patterns, and people's opinions about homeless pets. A 7-day observation log was also developed to gather information about free-roaming cats in Caldwell, TX. The objectives of this research were: (1) to evaluate the reliability of the telephone questionnaire, (2) to assess general cat ownership patterns, (3) to evaluate attachment level of pet owners to their pets, (4) to determine general opinions about free-roaming cats, (5) to determine if demographics were associated with opinions about free-roaming cat and dog problems and (6) to investigate free-roaming cat activity in a community. Telephone questionnaire information collected from 100 subjects was tested for reliability. Reliability was fair to good for cat level questions (sex, age, breed, length of time owned, indoor/outdoor status, litter, number of vet visits, vaccinated). Reliability was good for questions concerning subjects' knowledge of cat and dog behavior and levels of attachment to their pets. Reliability was excellent for all household level (demographic) variables. Reliability was moderate for questions regarding subjects' opinions about homeless animals. Telephone questionnaire responses collected from 441 subjects were checked for associations using exploratory logistic and linear regression models. A cat's role as a pet, vaccination status, and the length of time owned were associated with a cat's sterilization status. A cat's role as a pet was associated with the cat's indoor/outdoor status. Household size, education level and ethnicity of the owner were associated with cat ownership. Having children was associated with a negative opinion about homeless cats. Education level was associated with subjects' knowledge about dog and cat behavior. Gender, household size, and knowledge score were associated with subjects' attachment to their pets. Descriptive information on free-roaming cat activity was collected from 21 subjects using the 7-day observation log. Subjects made 382 cat sightings during the study period. Slightly more cat sightings were made during the morning than in the evening and afternoon. Most cats were spotted in neighborhoods and were resting or eating. Most of these cats that were eating were seen during the morning or evening hours.

Die Positronen-Emissions-Tomographie (PET) ist eine etablierte Methode zur Untersuchung von Stoffwechselvorgängen im Menschen. Sie wird als Werkzeug in der medizinischen Forschung ebenso wie klinisch als Diagnoseverfahren zur Erkennung von Metastasen eingesetzt. Dieses Projekt beschäftigt sich mit einer nichtmedizinischen Anwendung dieses bildgebenden Verfahrens – dem Aufbau und der Anwendung eines PET-Tomographen zur Untersuchung des Verhaltens von Schaum in Blasensäulen, dem Versuchsstand SCHAUMPET. Insbesondere wird auf die technische Realisierung des Projektes und die angewendeten Verfahren zur Bildgewinnung eingegangen. Am Beispiel von Natriumcapronat wird gezeigt, dass sich die Anreicherung eines Tensids in einer Schaumschicht mit Hilfe der Positronen-Emissions-Tomographie nachweisen lässt.

Thesis (D. Phil.(MW)--University of Pretoria, 2001. / Includes Bibliographical references (p. 360-391).