A tomografia computadorizada por emissão de fóton único (SPECT) é uma das modalidades de diagnóstico na Medicina Nuclear em que se detecta a radiação emitida por um radiofármaco previamente administrado ao paciente. Visto que osfótons emitidos sofrem interações com o corpo do paciente, fazem-se necessárias as correções de atenuação e de espalhamento a fim de melhor representar a distribuição do radiofármaco, e assimresultar em imagens mais precisas. O objetivo deste trabalho é avaliar os parâmetros anotados como padrão para reconstruções de imagens tomográficas e as correções de atenuação e de espalhamento em imagens SPECT do Hospital de Clínicas da Faculdade de Medicina da Universidade de São Paulo, por meio de análises qualitativas e quantitativas das imagens reconstruída a partir das aquisições tomográficas. Sob um protocolo de SPECT-CT cerebral modificado para duas janelas de aquisição, foram adquiridas imagens SPECT e SPECT-CT (BrightView XCT, Philips) utilizando fantomaJaszczak e reconstruídas pelos métodos FBP, MLEM e OSEM. Os resultados mostram que o método FBP apresenta imagens de baixa precisão devido à baixa SNR. A avaliação sugere o uso dos métodos iterativos MLEM e OSEM com correção de atenuação como método padrão de reconstrução de imagens de perfusão cerebral. De acordo com a avaliação de imagens do fantomaJaszczak e análise do contraste entre esfera fria ebackground,propõe-se análise observacional e avaliação das imagens clínicas reconstruídas pelo método OSEM com os parâmetros 3 iterações, 16 subsets, filtro Butterworth com frequência de corte 0,34 e potencia 1, como novos parâmetros padrão de reconstrução de imagens. / Single Photon Emission Computed Tomography (SPECT) is one of the diagnostic modalities in nuclear medicine, it detects the radiation emitted by a radioisotope previously administered to the patient. Since the photons undergo interactions with the patient\'s body,attenuationand scatteringcorrections are necessary in order to best represent the distribution of the radiopharmaceutical, and thus result in more accurate images. The aim of this study is to evaluate the standard parameters for tomographic imagesreconstruction, and attenuation and scatter corrections ofSPECT images, from Hospital das Clínicas da Faculdade de Medicina de RibeirãoPreto, Universidade de São Paulo, through qualitativeand quantitative analysis of the reconstructed image obtained from SPECT aquisitions. Though a modified to two windows of acquisition protocol for cerebral SPECT-CT, we acquired SPECT and SPECT-CT images (BrightView XCT, Philips) using phantom Jaszczak and the ones were reconstructed by FBP, MLEM and OSEM methods. The results show that the FBP method has poor image precision due to low SNR. The review suggests the use of iterative methods MLEM and OSEM with attenuation correction as a standard method of image reconstruction of cerebral perfusion. According to the images the phantom Jaszczak and contrast analysis between cold sphere and background, we propose observational analysis and evaluations of clinical images reconstructed by OSEM method with parameters 3 iterations, 16 subsets, Butterworth filter with cutoff frequency 0.34 and order 1, as newstandard parameters for image reconstruction parameters.

Este trabalho tem por objetivo a investigação de atenuação de ondas acústicas superficiais (OAS) em filmes finos granulares supercondutores de PbO e Pb depositados por sputtering reativo em substratos piezoelétricos de LiNbO3 e quartzo (ST). As medidas de atenuação de OAS em função da temperatura foram efetuadas para diferentes potências de radiofreqüência, e em freqüência variando de 550 MHz a aproximadamente 700 MHz. A atenuação de OAS medida em filme granular de chumbo (550&#197), dotada de alta resistividade de filme (de 1000 &#937/&#9001) se manifesta piezoeletricamente induzida e proporcional à resistividade do filme. No estado supercondutor esta medida de atenuação excede esta simples relação. Esta atenuação excedente é atribuída à resistência local produzida pela presença de dipolos de vórtice-antivórtice / The subject of this work is the investigation of surface acoustic waves (SAW) on superconducting Pb and PbO granular thin films deposited by sputtering on piezoelectric substrate (LiNbO3 and quartz ST). The SAW attenuation was measured as a function of the temperature (1,3K to 20K) for different r.f. Power, in frequencies from 550 MHz to 700 MHz. The SAW attenuation, measured on granular lead film (550 &#197) with high sheet resistivity (1000 &#937/&#9001) appears to be piezoelectrically induced and should be proportional to the sheet resistivity. In the superconducting state the measured attenuation exceeds this simple relation. This excess attenuation is ascribed to the local resistance produced by the presence of vortex-antivortex dipoles

O objetivo deste trabalho é a análise dos elementos de cortesia e atenuação no Português falado na região de São José do Rio Preto e no Espanhol falado na região de Málaga. Os corpora analisados foram obtidos por meio de entrevistas semidirigidas e fazem parte do Projeto ALIP Amostra Linguística do Interior Paulista, o brasileiro, e PRESEEA - Proyecto para el Estudio Sociolingüístico del Español de España y América, o espanhol. Analisamos um total de 24 entrevistas, sendo 12 de nível médio e 12 de superior, seis em cada idioma, divididas igualmente entre falantes do sexo feminino e do sexo masculino. Os falantes de nível médio tinham idades entre 25 e 45 anos, enquanto que a faixa etária entre os de nível superior era entre 50 e 70 anos. Partindo da teoria pragmática dos Atos de Fala e de estudos mais recentes sobre cortesia e atenuação de teóricos como Leech (2007), Bravo (2001, 2004, 2005), Kerbrat-Orecchioni (2004, 2005, 2006), entre outros, analisamos tanto a fala dos entrevistadores quanto a dos informantes. A partir da fala dos entrevistadores, pudemos observar como as perguntas, as solicitações de informações eram elaboradas em ambos os idiomas. Tal análise possibilitou a verificação de como o entrevistador se posicionava e quais eram as estratégias utilizadas verbos no imperativo, enunciados diretos, uso de atos de preparação ou verbos que visavam a proteger a face do informante. Já a análise da fala dos informantes objetivou a averiguação do uso de outras estratégias, cuja intenção era a defesa pessoal ou de terceiros, protegendo sua própria face ou a do entrevistador. Entre essas estratégias citamos a desfocalização do eu, a proteção à própria face ou à do outro, o uso de elementos atenuadores no momento de expressar opiniões, entre outras. Ao longo de nossa análise investigamos também o posicionamento de cada entrevista no eixo de solidariedade ou poder de acordo com a teoria de Brown e Gilman (1960). Para isso, foi necessário o estudo das formas de tratamento empregadas, bem como o uso ou não de formas nominais. Os resultados obtidos, dentro dos corpora estudados, mostram que a Língua Espanhola é uma língua de mais aproximação com o interlocutor, enquanto que a Língua Portuguesa denota maior distância. Observou-se ainda que determinados elementos como o uso de um tratamento mais formal no caso da Língua Portuguesa se caracteriza mais como uma estratégia conversacional do que uma distância social. / The present paper aims at the analysis of the politeness and attenuation elements in both the Portuguese spoken in São José do Rio Preto region and in the Spanish spoken in Malaga region. The studied corpora were obtained by means of partially guided interviews and are part of the ALIP Project (São Paulo\'s Countryside Linguistic Sampling), the Brazilian one, and the PRESEEA ( Project for the Sociolinguistic Study of the Spanish Spoken in Spain and America), the Spanish one. A total of 24 interviews were analysed, being 12 of those on an average level and the other 12 on a superior one, six in each language, equally divided into male and female speakers. The average level speakers range aged from 25 to 45 whereas the superior level ranged from 50 to 70. Considering the pragmatic theory of Speech Acts and other more recent studies on politeness and attenuation by theorists such as Leech (2007), Bravo (2001, 2004, 2005), Kerbrat-Orecchioni (2004, 2005, 2006), among others, both interviewers\' and interviewees\' speeches were analysed. From the interviewers\' speeches it was possible to observe how the questions, the information required, were built up in both languages. Such an analysis made possible verifying how the interviewer was positioned as well as which strategies were used: verbs in imperative, direct enunciations, preparation acts usage or verbs aiming at protecting the informer\'s face. Yet the informers\' speech analysis aimed at the inquiry of other strategies usage being the intention of such the personal or third parties\' defense, proctecting oneself\'s face or the interviewer\'s one. Among these strategies we mention defocusing the self, protecting oneself\'s own face or the other\'s one, attenuating elements usage when expressing opinions, among others. Throughout our analysis we investigated also the positioning of each interview coming to the axis solidarity or power according to Brown and Gilman\'s theory (1960). For such, it was made necessary the study of the treatment forms applied as well as the use or not of noun forms. The achieved results in the studied corpora showed that the Spanish language proves to be a language of more approximation coming to the interlocutor whereas the Portuguese language denotes more distance. It could also be noticed that certain elements such as the use of a more formal treatment coming to the Portuguese language are characterized more as a conversational strategy than as a social distance element.

Astrophysical models that address stellar energy generation and nucleosynthesis require a considerable amount of input from nuclear physics and are very sensitive to the detailed structure of nuclei, both stable and unstable. Radioactive nuclei play a dominant role in several stellar environments such as supernovae, X-ray bursts, novae etc. and nuclear data are important in the interpretation of these phenomena. When carbon, nitrogen and oxygen isotopes are present in substantial quantities in a star of sufficient mass, the fusion of four hydrogen nuclei to form a helium nucleus proceeds via the CNO cycles. Energy release in the CNO cycles is limited by the long lifetimes of 14O and 15O. In explosive stellar scenarios such as X-ray bursts, the energy output is very large, suggesting a breakout from the CNO cycles. 15O(α,γ)19Ne is the first reaction that breaks out of the CNO cycle. Nuclear structure information on high lying states in 19Ne is required to calculate the rate of the 15O(α,γ)19Ne reaction. This work focuses on the study of states in 19Ne above 3.53 MeV. The lifetimes of five states in 19Ne above 3.53 MeV were measured in this work. The states in 19Ne were populated via the 3He(20Ne,α)19Ne reaction at a beam energy of 34 MeV. The lifetimes were measured using the Doppler Shift Attenuation Method. The lifetimes of five states were measured and an upper limit was set on the lifetime of a sixth state. Three of the measurements are the most precise thus far. The lifetimes of the other three states agree with the values of the only other measurement of the lifetimes of these states. An upper limit on the rate of the 15O(α,γ)19Ne reaction was calculated at the 90% confidence level using the measured lifetimes. The contributions to the 15O(α,γ)19Ne reaction rate from several states in 19Ne at different stellar temperatures are discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis, entitled Wireless Sensor Networks in Hostile RF Environments, was submitted to the The University of Manchester by Mr Dominic James Patrick Crutchley on 30th April 2012 for the degree Doctor of Philosophy (PhD). This thesis considers two different but related aspects of wireless communication in Wireless Sensor Networks (WSNs) operating in hostile environments. Using grain as an example of a hostile environment, the influence of hostile, attenuating media on Radio Frequency (RF) communications was considered. Further to this the implications of a hostile environment for protocol stacks were considered, and a cross-layer, cross-application framework was proposed to help future protocol designers address these issues. To achieve both these aims, the software for a bespoke WSN node was designed and implemented. The node was characterised to ensure a good understanding of its RF behaviour and practical experiments were then conducted in a small-scale grain silo to gain an understanding of attenuation and data communications within grain. Finally, a real world implementation of the proposed cross-layer, cross-application framework was produced and a small example cross-layer protocol was demonstrated running on the WSN node. It was shown that a WSN can be used to characterise communications within a hostile medium and also that data communications are achievable within grain. It was also shown that a small cross-layer, cross-application framework could ease the development of cross-layered protocols in WSN software.

A higher frequency radio channel both increase the possible data rate and de- crease the required antenna size to efficiently transmit data. Higher frequency also introduce larger weakness to signal loss due to atmospheric effects. Al- phasat satellite conduct experiments for future use of higher frequencies by the Aldo Paraboni Payload. Budapest University of Technology have receiv- ing antennas for both transmitted Alphasat signals in the Ka band and Q band. Meteorological surface data is also gathered in close proximity of the receiving antennas. The relationship between the meteorological data and attenuation on the received signal is studied. A focus lies on the effects of water vapor and clouds.  International Telecommunication Union prediction methods for clouds and atmospheric gases are applied on the meteorological data. This provide a foundation for the analysis of received attenuation on the Q band signal at frequency 39,402 GHz. The analysis aim to investigate if there is any rela- tionship between surface meteorological data and atmospheric effects such as cloud and atmospheric gases. Cross-correlation was used to find similarities between the parameters.  The analysed data is over the month of April 2018. During this month seven different rain events were indicated by the rain rate tipping bucket. These regions showed strong influence of rain on the surface temperature and hu- midity was used to identify other regions with no rain characteristics. Only four out of 16 regions above 2,5 dB had no characteristics similar to rain with four other regions showing indistinguishable source. These eight regions were most promising of being caused by cloud and atmospheric gases. The large quantity of attenuation events below 2,5 dB made further manual analysis difficult. ITU methods predicted a maximum attenuation of 3 dB for clouds and atmospheric gases. Future work could improve analysis on attenuation events below 2,5 dB by pattern recognition with the characteristics found in this work.

This paper deals with the possibilities of designing the module for control of the attenuation of the optical signal. The paper describes basics of ber optic transmission and beam e ects. Variants of attenuation cells are characterized in this paper and based on the ndings a solution of the module for control of the attenuation of the optical signal is proposed. Practical section of the thesis deals with the design and physical construction of module for control of the attenuation of the optical signal using MEMS variable optical attenuator.

Whenever you touch yourself, that touch feels distinctly different from when someone else touches you. In particular, self-generated touch is perceived as less intense. This is a phenomenon called somatosensory attenuation. Touch to the self, regardless of self- or other generated, is perceived through a first-person perspective, whereas touch to other is perceived through a third-person perspective. The present study aimed to explore how self-touch is perceived when the self is observed through other perspectives. Here it was found that self-touch in a mirror and third-person perspective lowers the sense of ownership of the observed hand, as well as the agency of the touch. In particular, the sense of ownership and agency were lower in the third-person perspective relative to mirror perspective. Further, no qualitative differences in touch perception were observed across the three perspectives. There was no relationship between the sense of ownership and agency, and these qualitative differences. Lastly, there were no correlations between either of these experimental aspects (ownership, agency, qualitative) and autism traits and self-reported interoceptive abilities. The present study extends the knowledge and understanding of self-touch, and how visual perspective influences. The present study also highlights areas of applications, such as immersive virtual reality and clinical research.

[pt] Este trabalho se propõe a desenvolver um estudo de propagação na faixa VHF, visando determinar os efeitos de construções e irregularidades do terreno na atenuação dos sinais. Com este objetivo foi feito um levantamento dos sinais emitidos pelas estações de televisão da cidade do Rio de Janeiro (canais 4 e 13) em um número de pontos suficientes para caracterizar o comportamento da intensidade de campo nas diversas áreas da cidade. Na análise dos resultados foi dada ênfase especial a três aspectos distintos: distribuição estatística do sinal recebido, efeito da variação da altura da antena receptora e efeito da freqüência. Os resultados obtidos apresentam interesse prático para o dimensionamento de sistemas móveis na faixa VHF. / [en] The purpose of this work is to study the effect of constructions and terrain irregularities on the attenuation of VHF signals. To this end, television signals have been measured in the city of Rio de Janeiro (channels 4 and 13). In order to characterize the behavior of field intensity in different city areas, measurements were made in a sufficiently large number of points. In the analysis of the results, three distinct aspects have been given special emphasis: statistical distribution of the received signal, effect of receiving antenna height and effect of frequency. The results obtained show practical usefulness in the VHF mobile system projects.

Clinical ultrasound imaging techniques can be greatly improved by the use of ultrasound contrast agents (UCAs). While microbubbles (MBs) without shell are unstable and cannot be used for practical applications,a shell produced from biocompatible polyvinylalcohol (PVA) significantly improves chemical versatility and stability. The oscillation characteristics of a UCA are strongly dependent on concentration, applied pressure and viscoelastic parameters of the shell. Modifications in the shell as incorporation of antibodies or targeted molecules affect the bubble oscillation and resonance frequency of the MB suspension. In this presented work a tool for systematic characterization of UCAs is developed. Linear acoustic behaviour of PVA shelled MBs is examined. The acoustic driving pressure is kept below 100 kPa. The MB concentration is 1·10^{6} ml^{-1}. Attenuation and phase velocity profiles of ultrasound waves propagating through the UCA are measured using six narrow-band single crystal transducers that cover a frequency range between 1 and 15 MHz. The oscillation of a single bubble is modeled as a linear oscillator adapting HOFF’s model suitable for allshell thicknesses. The suspension is modeled through superposition of single bubbles. Knowing all parameters the resonance frequency of a MB suspension can be predicted. The model is fitted to experimental data to determine the viscoelastic shell parameters. The shell thickness is challenging to determine exactly and assumed to be either proportional to the outer shell radius or constant. Assuming a proportional shell thickness the calculated resulting shell parameters were shear modulus G_s = 14.5 MPa, shear viscosity η_s = 0.322 Pa·s and shell thickness d_s = 16 % of the outer radius. When instead assuming a constant shell thickness the determined parameters were in similar order of magnitude. Resonance frequency of the suspension was determined to 11.6 MHz. The developed tool can be used to characterize MBs with a modified shell independently of shell thickness and to predict resonance frequency of gas or air filled UCAs with known shell parameters.