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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.
1

Molecular Detection and Characterization of Avian Bornavirus

Mirhosseini, Negin 2011 May 1900 (has links)
Proventricular dilatation disease (PDD) was first recognized during an outbreak among captive macaws in the late 1970s. The disease, also known as proventricular dilatation syndrome or macaw wasting disease can occur in any psittacine but the most commonly affected birds are macaws, cockatoos and conures. The disease causes inflammation of the central, peripheral and autonomic nervous systems, as well as weight loss associated with regurgitation and the passage of undigested food in the feces. Although a viral etiology for PDD has been suspected for almost 40 years, the etiologic agent of the disease was unknown until lately. Recently we cultured a novel bornavirus from brain tissue from birds clinically diagnosed with PDD. This finding supports data from other groups who, in 2008, identified bornavirus sequences among birds suffering from PDD. It was reported that more 60 percent of PDD affected birds were infected with the new virus, designated avian bornavirus (ABV). ABV is a negative sense, single stranded RNA virus related to Borna disease virus (BDV). ABV isolates differ dramatically from BDV isolates in their level of genetic variation. Using polymerase chain reaction (PCR) assays, we were able to detect ABV in feces and tissue of PDD birds. We also detected ABV shedding from clinically healthy birds housed in aviaries with no history of the disease. We also determined the complete genome sequences of eight North American ABV isolates. Genotyping indicates that the majority of North American ABV isolates are genotype 4. We found one ABV, genotype 1, which is the first complete sequencing of this genotype. Moreover, we found ABV genotype 2, isolated from an apparently healthy cockatiel with no PDD clinical signs. In order to investigate whether this genotype is avirulent, the virus was grown in duck embryo fibroblasts and inoculated into two adult cockatiels by the oral and intramuscular routes. One bird developed clinical signs on day 33 and was euthanized on day 36. The second challenged bird developed clinical signs on day 41 and was euthanized on day 45. On necropsy, the proventriculus of both birds was slightly enlarged and microscopic examination showed lesions consistent with PDD in the brain, spinal cord, heart, adrenal gland and intestine. A control, uninoculated cockatiel was apparently healthy when euthanized on day 50. ABV2 is now the second ABV genotype to be formally shown to cause PDD.
2

Clinical study of the use of Photodynamic Detection (PDD) in assessing suspicious oral lesions

Al-Juboori, Jamal Noori Ahmed January 2011 (has links)
Photodynamic Detection (PDD) is a diagnostic technique involving administration of a photosensitizer to the targeted cells that can be stimulated by short wavelength light which then leads to emission of light at a different wavelength (lower energy). The light emitted by the cells can be detected and analysed (by a spectroscope). All cells have the innate ability (due to endogenous fluorophores) to fluoresce, termed autofluorescence. Any cellular, metabolic or structural changes can alter the fluorescence intensity peaks. In this study 5-aminolevulinic acid (5-ALA) photosensitizer prodrug was used, which is metabolised in highly active cells to protoporphyrin IX (PpIX). Excitation of a cell at 405nm wavelength (light) leads to emission of autofluorescence at 500nm and PpIX at 635nm. The purpose of this investigation was to evaluate the use of compact spectroscopy together with the photosensitizer prodrug 5-ALA, in assessing clinically suspicious oral lesions. To that end the followings were assessed: • The fluorescence intensity ratio (FIR) or Red/Green ratio at 635/500nm measurements of normal anatomical sites at ten oral anatomical sites to map and create baseline readings for normal oral mucosal site fluorescence. • The effect of participants’ characteristics on the normal oral mucosal site FIR measurements. • The use the fluorescence intensity ratio (FIR) measurements to determine any differences between the lesion and the normal oral readings and whether the FIR from clinically suspicious oral lesions is associated with the histopathology grade. In addition to the sensitivity and specificity of the technique in assessing clinically suspicious (premalignant) oral lesions for potential malignant change.Prior to the trial commencing, approval were obtained from the Research Ethics Committee (REC), local NHS Research and Development (R&D), and Medicine Healthcare product Regulatory Agency (MHRA) and the University of Dundee Research Innovation Services (RIS). A total of thirty five participants with clinically suspicious oral lesions were recruited in Dundee (Dundee Dental Hospital) and Glasgow (Southern General Hospital). A Photodynamic Detection method using compact fluorescence spectroscopy and 5-ALA mouth rinse was applied. FIR measurements from ten normal anatomical sites were obtained in every patient to study the variation at different normal oral sites and the effect of the participant’s characteristics on these readings. In addition, two FIR measurements were obtained from each lesion and a further one taken from normal looking mucosa well beyond the lesion boundary (i.e. more than 5mm away) prior to biopsy. The readings were compared to study the reliability, reproducibility and efficacy of the photodynamic method in detecting mucosal abnormality. A total of 292 spectral readings obtained from normal mucosa were used to study the FIR measurements at normal oral anatomical sites. The results showed that the oral regions could be grouped into two broad categories with similar readings, the palatal and tongue readings in one group and buccal, ventral tongue, floor of the mouth, gingiva and lip mucosa on the other (essentially keratinized and non keratinized groups). The same set of readings were further analysed to study the effect of individual characteristics (age, gender, presence of oral prosthesis, metabolic diseases, smoking and alcohol consumptions) on the FIR measurements. There was no significant difference between FIR measurements within each of the groups studied, although at times sample sizes were very small.A total of 134 spectral readings obtained from 47 lesions that were biopsied from 35 patients recruited to the trial were used for the next part of the study. There were 91 spectra obtained from the lesions and 43 spectra obtained from the normal sites (more than 5mm away from the borders of the lesion) for comparison. There was a significant difference between the lesion and normal site readings. The FIR readings for the dysplastic lesions were significantly different when compared with the normal and benign hyperkeratoses. However there was no significant difference between dysplastic and inflammatory lesions (lichen planus, lichenoid lesions and candidal leukoplakia) on the one hand and inflammatory lesions and hyperkeratotic lesion on the other. Further analysis showed the sensitivity in detecting all the clinically suspicious oral lesions from the normal sites was 59.5% and specificity was 73.8%. The sensitivity in detecting dysplasia from normal sites was 100% and specificity 100%.Photodynamic Detection was able to detect a difference between the oral lesions from normal mucosa (but so is the naked eye!). However there was variation in the sensitivity and specificity in detecting a range of different pathological conditions. The technique was highly sensitive in detecting dysplasia from normal mucosa but unfortunately the technique is not able to discriminate reliably between dysplasia and inflammatory lesions whose clinical appearance can be very similar. In conclusion, the photodynamic detection method used in this study would not appear to offer a reliable screening tool for the early detection of oral dysplasia/cancer. The need to consider adjunctive tests that discriminate inflammation from dysplasia is required. Photodynamic Detection (PDD) is a diagnostic technique involving administration of a photosensitizer to the targeted cells that can be stimulated by short wavelength light which then leads to emission of light at a different wavelength (lower energy). The light emitted by the cells can be detected and analysed (by a spectroscope). All cells have the innate ability (due to endogenous fluorophores) to fluoresce, termed autofluorescence. Any cellular, metabolic or structural changes can alter the fluorescence intensity peaks. In this study 5-aminolevulinic acid (5-ALA) photosensitizer prodrug was used, which is metabolised in highly active cells to protoporphyrin IX (PpIX). Excitation of a cell at 405nm wavelength (light) leads to emission of autofluorescence at 500nm and PpIX at 635nm. The purpose of this investigation was to evaluate the use of compact fluorescence spectroscopy together with the photosensitizer prodrug 5-ALA, in assessing clinically suspicious oral lesions. To that end the followings were assessed: • The fluorescence intensity ratio (FIR) or Red/Green ratio at 635/500nm measurements of normal anatomical sites at ten oral anatomical sites to map and create baseline readings for normal oral mucosal site fluorescence. • The effect of participants’ characteristics on the normal oral mucosal site FIR measurements. • The use the fluorescence intensity ratio (FIR) measurements to determine any differences between the lesion and the normal oral readings and whether the FIR from clinically suspicious oral lesions is associated with the histopathology grade. In addition to the sensitivity and specificity of the technique in assessing clinically suspicious (premalignant) oral lesions for potential malignant change. Prior to the trial commencing, approval were obtained from the Research Ethics Committee (REC), local NHS Research and Development (R&D), and Medicine Healthcare product Regulatory Agency (MHRA) and the University of Dundee Research Innovation Services (RIS). A total of thirty five participants with clinically suspicious oral lesions were recruited in Dundee (Dundee Dental Hospital) and Glasgow (Southern General Hospital). A Photodynamic Detection method using compact fluorescence spectroscopy and 5-ALA mouth rinse was applied. FIR measurements from ten normal anatomical sites were obtained in every patient to study the variation at different normal oral sites and the effect of the participant’s characteristics on these readings.
3

Sleep-wake characteristics of children with pervasive developmental disorders (PDD) : a survey study

Chiang, Chia-Jung 18 February 2013 (has links)
A higher prevalence of sleep problems and a few specific sleep-wake characteristics have been preliminarily found to be associated with pervasive developmental disorders (PDD). However, there is limited research that has examined multiple variables associated with sleep-wake characteristics and problems of children with PDD. This dissertation study assessed and examined the sleep-wake characteristics, sleep problems, and daytime problem behaviors of children with PDD aged three to fifteen years, and their caregivers’ sleep as well as contextual variables using data from the primary caregivers’ reports and recordings. This study confirmed several findings in the literature related to sleep-wake characteristics and sleep problems in children with both PDD and sleep problems. Although the relationship between sleep and daytime problem behaviors of the children was not found to be statistically correlated, the descriptive data indicated that some conditions such as illness or anxiety of the children negatively impacted their sleep and behaviors. In addition, the children participants with PDD and sleep problems tended to watch TV or to use computer/play video games before bedtime, in comparison to those with PDD but without sleep problems in this study. Moreover, a significant correlation between sleep of the caregivers and of their children was found in the group of children with PDD and sleep problems, but not in the other group of children with PDD but without sleep problems. Lastly, the results of this study showed that the children with diagnoses of PDD were 3.84 times more likely to have sleep problems than those with diagnoses of Asperger’s Disorder (AD) or PDD not otherwise specified (PDD-NOS). These findings are discussed in light of the similarities and differences between the current study and previous literature, and with respect to the implications for practice and research in the field of PDD and sleep. / text
4

Estudo radiográfico retrospectivo das alterações do proventrículo em psitacídeos / Retrospective radiographic study of proventricular abnormalities among psittacines

Praes, Patricia Lima 07 October 2013 (has links)
Este estudo retrospectivo revisa os achados radiográficos em exames simples e contrastados de 38 aves psittaciformes com alterações no proventrículo. Os dados foram obtidos do Serviço de Diagnóstico por imagem do departamento de cirurgia junto ao Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, durante o período de janeiro de 2004 a abril de 2012. A distribuição das alterações, assim como as suas respectivas espécies e idades, foram estudadas. O sexo das aves não foi considerado neste estudo. A espécie Amazona aestiva (papagaio-verdadeiro) alcançou a porcentagem mais elevada (44,8%) entre as diversas ordens, seguidos pelos Nymphicus hollandicus (Calopsita) (28,9%). Neste período de oito anos, os sintomas mais comuns observados na anamnese foram a \"apatia/prostração\" e \"anorexia/prostração\" (52,63% cada). Entre as suspeitas clínicas mais frequentes, a doença da dilatação do proventrículo (PDD) foi a mais citada (26,32%). O achado radiográfico mais frequentemente observado foi a \"dilatação do proventrículo por conteúdo de radiodensidade gás e líquido\" (34,21%). A medição do proventrículo foi um dado descrito em 34,84% dos laudos. Dentre as aves estudadas com alterações radiográficas em proventrículo, o exame radiográfico contrastado por sulfato de bário foi solicitado em 26,32% dos casos, onde o achado radiográfico mais comum foi a \"retenção do meio de contraste ou evolução lenta do mesmo\". Dentre os casos com suspeita clínica de PDD, os únicos nos quais foi possível obter confirmação foram aqueles em que foi solicitado o exame contrastado. Algumas aves também exibiram alterações radiográficas inespecíficas. A dilatação de proventrículo em si não é patognomônica para PDD, visto que esta pode vir de forma atípica e que há diversas outras doenças que causam alterações semelhantes. / This retrospective study examines radiographic findings of plain and contrastenhanced examinations of 38 psittacine birds presenting proventricular abnormalities. The data were obtained by the Image Diagnostic Service of the Veterinary Hospital of the School of Veterinary Medicine and Animal Science of the University of São Paulo between January 2004 and April 2012. The distribution of the abnormalities, as well as the birds species and ages, were also investigated. The birds sex was not taken into account. The highest percentage among the different orders (44.8%) was observed among specimens of Amazona aestiva (Blue-fronted Parrot), followed by Nymphicus hollandicus (Cockatiel) (28.9%). In the eight-year period of the study, the most common symptoms were \"apathy/weakness\" and \"anorexia/weakness\" (52.63% each.) Proventricular Dilatation Disease (PDD) was the most frequent clinical suspicion (26.32%.) The most commonly observed radiographic abnormality was a \"Proventricular dilatation caused by content of gas and water radiodensity\" (34.21%.) The measurements of the proventriculus were described in 34.84% of all reports. Among the birds studied with radiographic alterations in proventriculus, radiographic examination contrasted by barium sulfate was required in 26.32% of cases. The most common findings were \"retention or slow transit of the contrast agent\". The only cases with a clinical suspicion of PDD for which it was possible to obtain a confirmation were those for which a contrast-enhanced examination was ordered. Some birds also presented radiographic abnormalities of uncertain diagnosis. A proventricular dilatation in itself is not pathognomonic of PDD inasmuch as said disease may present in an atypical manner and several other diseases may cause similar abnormalities.
5

Estudo radiográfico retrospectivo das alterações do proventrículo em psitacídeos / Retrospective radiographic study of proventricular abnormalities among psittacines

Patricia Lima Praes 07 October 2013 (has links)
Este estudo retrospectivo revisa os achados radiográficos em exames simples e contrastados de 38 aves psittaciformes com alterações no proventrículo. Os dados foram obtidos do Serviço de Diagnóstico por imagem do departamento de cirurgia junto ao Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, durante o período de janeiro de 2004 a abril de 2012. A distribuição das alterações, assim como as suas respectivas espécies e idades, foram estudadas. O sexo das aves não foi considerado neste estudo. A espécie Amazona aestiva (papagaio-verdadeiro) alcançou a porcentagem mais elevada (44,8%) entre as diversas ordens, seguidos pelos Nymphicus hollandicus (Calopsita) (28,9%). Neste período de oito anos, os sintomas mais comuns observados na anamnese foram a \"apatia/prostração\" e \"anorexia/prostração\" (52,63% cada). Entre as suspeitas clínicas mais frequentes, a doença da dilatação do proventrículo (PDD) foi a mais citada (26,32%). O achado radiográfico mais frequentemente observado foi a \"dilatação do proventrículo por conteúdo de radiodensidade gás e líquido\" (34,21%). A medição do proventrículo foi um dado descrito em 34,84% dos laudos. Dentre as aves estudadas com alterações radiográficas em proventrículo, o exame radiográfico contrastado por sulfato de bário foi solicitado em 26,32% dos casos, onde o achado radiográfico mais comum foi a \"retenção do meio de contraste ou evolução lenta do mesmo\". Dentre os casos com suspeita clínica de PDD, os únicos nos quais foi possível obter confirmação foram aqueles em que foi solicitado o exame contrastado. Algumas aves também exibiram alterações radiográficas inespecíficas. A dilatação de proventrículo em si não é patognomônica para PDD, visto que esta pode vir de forma atípica e que há diversas outras doenças que causam alterações semelhantes. / This retrospective study examines radiographic findings of plain and contrastenhanced examinations of 38 psittacine birds presenting proventricular abnormalities. The data were obtained by the Image Diagnostic Service of the Veterinary Hospital of the School of Veterinary Medicine and Animal Science of the University of São Paulo between January 2004 and April 2012. The distribution of the abnormalities, as well as the birds species and ages, were also investigated. The birds sex was not taken into account. The highest percentage among the different orders (44.8%) was observed among specimens of Amazona aestiva (Blue-fronted Parrot), followed by Nymphicus hollandicus (Cockatiel) (28.9%). In the eight-year period of the study, the most common symptoms were \"apathy/weakness\" and \"anorexia/weakness\" (52.63% each.) Proventricular Dilatation Disease (PDD) was the most frequent clinical suspicion (26.32%.) The most commonly observed radiographic abnormality was a \"Proventricular dilatation caused by content of gas and water radiodensity\" (34.21%.) The measurements of the proventriculus were described in 34.84% of all reports. Among the birds studied with radiographic alterations in proventriculus, radiographic examination contrasted by barium sulfate was required in 26.32% of cases. The most common findings were \"retention or slow transit of the contrast agent\". The only cases with a clinical suspicion of PDD for which it was possible to obtain a confirmation were those for which a contrast-enhanced examination was ordered. Some birds also presented radiographic abnormalities of uncertain diagnosis. A proventricular dilatation in itself is not pathognomonic of PDD inasmuch as said disease may present in an atypical manner and several other diseases may cause similar abnormalities.
6

Quantification of glacier melt volume in the Indus River watershed

Asay, Maria Nicole 07 December 2011 (has links) (PDF)
Quantifying the contribution of glaciers to water resources is particularly important in locations where glaciers may provide a large percentage of total river discharge. In some remote locations, direct field measurements of melt rates are difficult to acquire, so alternate approaches are needed. Positive degree-day modeling (PDD) of glacier melt is a valuable tool to making first order approximations of the volume of melt coming from glaciers. In this study, a PDD-melt model is applied to glaciers in the Indus River watershed located in Afghanistan, China, India, and Pakistan. Here, millions of people rely on the water from the Indus River, which previous work suggests may be heavily dependent on glacier melt from high mountain regions in the northern part of the watershed. In this region, the PDD melt model calculates the range of melt volumes from more than 45,000 km2 of glaciated area. It relies on a limited suite of input variables for glaciers in the region: elevation, temperature, temperature lapse rate, melt factor, and surface area. Three global gridded climate datasets were used to determine the bounds of temperature at each glacier: UEA CRU CL 2.0, UEA CRU TS 2.1, and NCEP/NCAR 40 year reanalysis. The PDD melt model was run using four different melt scenarios: mean, minimum, maximum, and randomized. These scenarios account for differences in melt volume not captured by temperature, and take uncertainties in all input parameters into account to bound the possible melt volume. The spread in total melt volume from the model scenarios ranges between 27 km3 and 439 km3. While the difference in these calculations is large, it is highly likely the real value falls within this range. Importantly, even the smallest model volume output is a significant melt water value. This suggests that even when forcing the absolute smallest volume of melt, the glacier contribution to the Indus watershed is significant. In addition to providing information about melt volume, this model helps to highlight glaciers with the greatest contribution to total melt. Despite differences in the individual climate models, the spatial pattern in glacier melt is similar, with glaciers contributing the majority of total melt volume occurring in similar geographic regions regardless of which temperature dataset is used. For regions where glacier areas are reasonably well-constrained, contributions from individual glaciers can be quantified. Importantly, less than 5% of glaciers contribute at least 70% of the total melt volume in the watershed. The majority of these glaciers are in Pakistan, the region with the largest percentage of known glaciers with large surface areas at lower elevations. In addition to calculating current melt volumes over large glaciated areas, this model can also be used to determine future melt rates under differing climate scenarios. By applying suggested future regional temperature change to the temperature data, the impact on average melt rate over the watershed was found to increase from 3.02 m/year to 4.69 m/year with up to 2 °C temperature increase. Assuming glacier area remains relatively constant over short time periods, this would amount to a 145 km3 increase in melt volume.
7

Specifying the Boundaries of Pervasive Developmental Disorder - Not Otherwise Specified: Comparisons to Autism and other Developmental Disabilities on Parent-Reported Autism Symptoms and Adaptive and Behavior Problems

Snow, Anne V. 09 September 2009 (has links)
No description available.
8

Evaluation of the Pervasive Developmental Disorder Behavior Inventory

Hall, Kristy Lynne 15 September 2010 (has links)
No description available.
9

Estudos dosimétricos em interfaces teciduais em radioterapia utilizando dosimetria por ressonância paramagnética eletrônica EPR / Studies on Tissue Interfaces Dosimetry in Radiotherapy Using Electron Paramagnetic Resonance Dosimetry by EPR

Ramirez, Jose Luis Javier Vega 28 July 2010 (has links)
A acurácia e precisão exigida nas novas técnicas radioterápicas é bastante elevada, como no caso da Radioterapia com Intensidade Modulada (IMRT). Desta forma, o tamanho dos dosímetros a serem utilizados nas medidas experimentais é um fator crítico. Além disso, a ausência de equilíbrio eletrônico lateral e a existência de intensos gradientes de dose no campo apresentam um desafio na determinação da dose administrada no tumor. Alguns dos dosímetro utilizados atualmente não apresentam resolução espacial ou sensibilidade condizentes com os requisitos das dosimetrias clínicas nessas técnicas radioterápicas. A dosimetria por Ressonância Paramagnética Eletrônica (EPR), utilizando o aminoácido L-alanina como dosímetro, é um método amplamente aceito de dosimetria para medições de altas doses de radiação. O objetivo desta tese foi aprofundar o desenvolvimento da dosimetria por EPR, como um método competitivo para aplicações na radioterapia, que preencha os requisitos de precisão e acurácia e comparar medidas realizadas com os minidosímetros de L-alanina/ EPR com outras técnicas e algoritmos estudados. A nova metodologia dos minidosímetros com 95% L-alanina e 5% PoliVinil Álcool (PVA) de 1 mm de diâmetro e 3 mm de altura com massa 3,5 mg a 4,0 mg., foi utilizadas para medições de porcentagem de dose profunda (PDP) e perfis de campo de irradiação em objetos simuladores físicos (objetos simuladores não homogêneos) irradiados com a técnica da radioterapia. Os objetos simuladores não homogêneos foram construídos com materiais equivalentes que simulam o tecido mole, pulmão, osso e outras estruturas do corpo humano como o titânio, que é utilizado em próteses. Os objetos simuladores foram irradiados com fótons de energia máxima de 6 MeV do acelerador linear Siemens Primus com uma dose de 20 Gy aproximadamente. Os resultados obtidos experimentalmente com os minidosímetros de L-alanina foram comparados com outros procedimentos e técnicas já validadas como, por exemplo, o filme, o sistema de planejamento do tratamento (SPT) e a simulação Monte Carlo com o código PENELOPE-2008, que possibilitou a comparação de dados experimentais com dados obtidos pelo sistema de planejamento, e análise do comportamento das doses na interface de diversos materiais equivalentes a tecidos. As curvas de porcentagem de dose profunda (PDP) simuladas com o PENELOPE foram validadas pelas PDPs do setor de Radioterapia do HCFMRP-USP e utilizadas como padrão dosimétrico para nosso estudo. A menor diferença percentual entre a dose absorvida no caso simulado comparado ao experimental foi de 0,12%, e a maior de 7,2%. O material de maior absorção de dose foi o Titânio com um fator de atenuação de 40,43%. Os resultados obtidos neste trabalho demonstram que o sistema dosimétrico utilizando EPR com minidosímetros de 95% L-alanina e 5% PVA apresentam grande potencial na determinação de dose nas aplicações das novas técnicas de Radioterapia de pequenos campos. / The accuracy and precision required in new radiation techniques is quite high, as is the case of Intensity Modulated Radiotherapy (IMRT). Thus, the size of the dosimeters to be used in experimental measurements is critical. Moreover, the absence of lateral electronic equilibrium and the existence of intense dose gradients in the field present a challenge in determining the dose in the tumor. Some of the dosimeter used nowadays do not have spatial resolution or sensitivity consistent with the requirements of clinical dosimetry in these radiation techniques. The Electron Paramagnetic Resonance (EPR) dosimetry using the amino acid L-alanine as a dosimeter is a widely accepted method of dosimetric measurements of high-dose radiation. The goal of this thesis was to deepen the development of EPR dosimetry as a competitive method for applications in radiotherapy, fulfilling the requirements of precision and accuracy and compare measurements performed with L-alanine / EPR minidosimeters with other techniques and algorithms investigated. The new methodology of minidosimeters with 95% L-alanine and 5% polyvinyl alcohol (PVA), of 1 mm in diameter and 3 mm in height and with a mass 3.5 mg to 4.0 mg, was used for measurements of percentage depth dose (PDD) and field profiles in phantoms (inhomogeneous phantoms) irradiated with radiotherapy technique. The inhomogeneous phantoms were constructed with materials that simulate the soft tissue, lung, bone and other structures of the human body such as titanium, which is used in prostheses. The phantoms were irradiated with photons of 6 MeV maximum energy from a Siemens Primus linear accelerator with a dose of approximately 20 Gy. The results obtained experimentally with the L-alanine minidosimeters were compared with other procedures and techniques already validated such as, for example, film, treatment planning system (TPS) and Monte Carlo simulation with the code PENELOPE-2008, which allowed data comparison with the treatment planning system and an analysis of doses in the interface of different materials equivalent to the tissues. The curves of percentage depth dose (PDP) simulated with PENELOPE were validated with data from the Sector of Radiotherapy of HCFMRP-USP and were used as a dosimetric standard in this study. The lowest difference between simulated and experimental doses was 0.12% and the higher was 7.2%. The material with larger absorption was the Titanium with an attenuation factor of 40.43%. The present results demonstrate that the dosimetric system using EPR minidosimeters with 95% L-alanine and 5% PVA has a great potential in determining the dose from small fields new techniques in radiotherapy.
10

TRP channels and regulation of blood flow in the brood patch of Zebra finches (Taeniopygia guttata)

Silverå Ejenby, Malin January 2010 (has links)
<p>During the breeding season Zebra finch, Taeniopygia guttata, females develops a brood patch on the ventral surface which facilitates heat exchange between the incubating bird and the egg. The brood patch has to be sensitive to changes in temperature, so that the eggs can be kept at an optimal temperature for embryo development. If the egg temperature drops it has to be re-warmed. Mild cooling of the brood patch has been shown to cause cold induced vasodilation, but the responsible mechanism for this is not known. In this study we investigated if known thermoreceptors, TRPV3 and TRPV4, could be involved in the alteration of blood flow. To activate TRPV3 and TRPV4 two agonists, carvacrol and 4α-PDD respectively, were applied on the brood patch. Changes in skin temperature and vascularity were then examined. The results obtained did not reveal any changes in the vascularity. Temperature changes in the skin that could be caused by an alteration in blood flow did not significantly change either. Still, a role of these channels in the brood patch cannot be excluded.</p>

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