Neste trabalho foram estudadas as nanopartículas magnéticas (NPs) de interesse em biomedicina de Fe3O4 e de Fe3O4 dopadas com Gd 5% pela técnica de Espectroscopia de correlação angular gama-gama perturbada (CAP). As amostras de Fe3O4 foram sintetizadas pelos métodos de co-precipitação e decomposição térmica e as nanopartículas de Fe3O4 dopadas com Gd 5% foram sintetizadas pelo método da coprecipitação. As amostras de nanoparticulas foram caracterizadas quanto a sua estrutura pela difração de raios X (DRX) e quanto ao seu tamanho pela técnica de microscopia eletrônica de transmissão (TEM). Os resultados mostram que as nanoparticulas de ferrita mostram estrutura pertencente ao grupo espacial Fd3m e que seu tamanho é de 10 nm quando sintetizada por decomposição térmica e entre 7 e 15 nm quando sintetizada por co-precipitação. As nanopartículas de Fe3O4 sintetizadas pelo método de decomposição térmica apresentaram maior monodispersão do que as nanopartículas sintetizadas pelo método de co-precipitação, ou seja, o tamanho de grão estava mais homogêneo. A técnica CAP mostrou que a variação de tamanho das nanopartículas infuencia no comportamento magnético das mesmas e o dopante Gd atrapalha a introdução da sonda radioativa por competir pelos sítios de Fe. / In the work reported in this dissertation, magnetic nanoparticles of Fe3O4 and 5% Gddoped Fe3O4, which have applications in biomedicine, were studied by Perturbed Gamma-Gamma Angular correlation spectroscopy (PAC). Fe3O4 samples were synthesized by both, co-precipitation and thermal decomposition methods. Gd-doped Fe3O4 magnetic nanoparticles were synthesized only by co-precipitation method. Analysis of X-ray diffraction (XRD) showed that the samples belong to Fd3m space group. Transmission Electron Microscopy (TEM) showed that nanoparticles have sizes between 5 and 14 nm, suitable for biomedical applications. Fe3O4 nanoparticles synthesized by thermal decomposition method showed greater monodispersed nanoparticles than the samples synthesized by co-precipitation method. PAC technique using radioactive probe 111In (111Cd) showed that the size of the nanoparticles changes magnetic behavior and for the Gd-doped sample PAC measurements results showed that the introduction of radioactive probe is difficult due the presence of an impurity (Gd) and there is a competition for Fe sites between Gd and nuclear probe.

Tese de mestrado integrado. Engenharia Civil (Estruturas). Universidade do Porto. Faculdade de Engenharia. 2011

Volunteers play a critical role to Extension by assisting with program planning, provide input and guidance in what direction local Extension programs should take, and provide assistance with program implementation and evaluation. Extension volunteers have been utilized in Extension for over 50 years, serving on program area committees to develop programs that meet the needs of local clientele. This study evaluated Agriculture and Natural Resource Program Area Committee (Ag/NR PAC) members located in 36 Texas counties. The selection of counties was based upon Texas AgriLife Extension Service county categories. A quantitative, ex post facto, survey instrument was developed that consisted of Likert type statements that focused on the purpose, responsibilities, qualifications, time obligations, County Extension Agent interaction, subject matter specialist interactions and assisting with educational event implementation and evaluation. The survey was mailed with a postage paid return envelope and return surveys were accepted for 45 days. The data was analyzed using SPSS 16.0 for Windows software. The findings of this study showed that Ag/NR PAC members have an overall understanding of the purpose, responsibilities and qualifications of PAC's. Overall, the data shows that County Extension Agents are remaining involved with the program area committees. However, 42 percent of the respondents disagreed or remained neutral to subject matter specialists being utilized in committee meetings. The open ended questions show that program area committee members consider personnel education as a motivational factor for serving on the Ag/NR committees. Committee members feel strongly about assisting with program planning and attending the educational programs but are not remaining actively involved in the evaluation or interpretation phase of the programs. The findings of this study resulted in seven associated recommendations related to working with Ag/NR PAC's. In addition, six areas were identified for areas of research to be considered for the future. The results found that Ag/NR PAC's are still a crucial part of Texas AgriLife Extension Service and they play an important role in identifying issues at the local level. The information found within the study will contribute to working with volunteers to enhance the program planning process.

Background. PAC controller is a strengthened version of PLC controller. Its function is very similar, but its essence and construction are different. PLC and PAC have many successful applications in the field of industrial automation control. There is a lot of literature about the software architecture of PLC control system. However, there is almost no relevant literature on software architecture based on PAC control system. A well-performing and stable automatic control system is indispensable to the design and development of suitable software architecture. The quality and pattern of software architecture can even affect the stability and efficiency of the control system. Objectives. Based on these problems, we defined two primary objectives. The first is to investigate the architecture of some existing large industrial control systems, to analyze and summarize the scenarios and advantages and disadvantages of these architectural patterns. The second, based on the results of effort for the first objective, we want to propose and design a set of automated control solution architecture model based on PAC control system, which is implemented and applied in a printing house. In the process, we sum up the challenges and obstacles encountered in implementing the solution and provide some guidance or reference for those involved in the field. Methods. For the first objective, we used a systematic literature review to collect data about existing ICS architecture. Concerning the second objective, a case study was conducted in a printing house in Karlskrona Sweden, in the study, we proposed a software architecture model suitable for PAC automation control system. Then, we developed and tested the automation control system and summarized some challenges and obstacles in the process of the implementation. Results. The existing ICS (Industrial Control System) architecture models and critical problems and challenges in the implementation of ICS are identified. From the existing literature, we have summarized five commonly used large industrial control system architecture models, which are mainly using composite structures, that is, a combination of multiple architecture patterns. Also, some critical problems in the industrial control system, such as information security, production reliability, etc. are also identified. In the case study, we put forward an automatic control solution for Printing House based on SLR results. We designed the hardware deployment architecture of the system and the software control architecture. Generally speaking, this architecture is based on C/S architecture. In the development of client, we adopt the popular MVC architecture mode. In the longitudinal view of the whole system, an extended hierarchical architecture model is adopted. In the core control system, we adopt the modular architecture design idea. The whole control system is composed of 6 parts, four subsystems of PAC terminal, one server-side program and one client program. After a long time, development and test, our system finally goes online for the production, and its production efficiency is improved compared with the old system. Its expansion functions, such as Production Report and Tag Print, are deeply satisfying for the customers. Conclusions. In this research, we summarize and compare the advantages and disadvantages of several commonly used industrial control systems. Besides, we proposed a software architecture model and developed an automation control system based on PAC. We fill the gap that there is a lack of studies about the software architecture about the implementation of the automation control system based on PAC. Our result can help software engineers and developers in ICS fields to develop their own PAC based automation control system.

Este trabalho propõe e avalia um novo algoritmo para o posicionamento de células de circuitos que utilizam a metodologia de projeto TRANCA. O algoritmo proposto realiza o posicionamento por particionamento, em n-blocos, baseado no conceito de balanceamento de redes, realizando um pré-roteamento global. A maioria dos algoritmos de posicionamento por particionamento são baseados na heurística de Kernighan-Lin[KER 70] e Fidducia-Mattheyses[FID 82] com migração de grupos. Estes algoritmos utilizam uma função de corte mínimo para diminuir o cruzamento de redes entre as duas partições, produzindo regiões saturadas. Sendo assim, o conceito de balanceamento de redes significa a busca de um equilíbrio no comprimento das conexões para evitar a criação de regiões saturadas, diminuindo o tempo computacional e facilitando a etapa de roteamento. Apresenta-se uma visão geral de síntese automática. Descreve-se os estilos de projeto mais utilizados, define-se e analisa-se o problema de particionamento e posicionamento de células. As principais características da metodologia TRANCA são apresentadas. Resume-se as principais características das ferramentas de síntese TRANCA, destacando-se as etapas de particionamento e posicionamento de cada uma, visando o aproveitamento destas características positivas. Com o propósito de fundamentar os conceitos usados para o desenvolvimento do algoritmo, apresenta-se os métodos de posicionamento mais relevantes, dando destaque aqueles baseados em particionamento. Descreve-se algumas das heurísticas existentes. Os conceitos utilizados para o desenvolvimento do algoritmo são então descritos. O algoritmo consiste basicamente da distribuição das conexões, utilizando um mapa de congestionamento do circuito, o que caracteriza um pré-roteamento global. O mapa de congestionamento é montado sobre as partições geradas no circuito. Além do mapa de congestionamento, a descrição dos caminhos das redes é realizada sobre um modelo definido para controlar o cruzamento de redes. Apos a definição dos conceitos, o ambiente criado para o algoritmo é apresentado. Com o objetivo de validar os conceitos estudados e aqueles propostos, implementou-se um protótipo, chamado TRAPP(TRAnsparent Placement by Partitioning), e um visualizador de posicionamento chamado CIPPATO. Finalmente, alguns resultados do protótipo desenvolvido e uma avaliação sobre o comportamento dente protótipo são apresentados. Propõe também implementações alternativas e direções para trabalhos futuros. / This work proposes and evaluates a new algorithm for cells' placement, for use on TRANCA[REI 87] layouts. The algorithm proposed makes a placement by partitioning using multiple steps, based on the concept of net balancing, in order to make a global prerouting. Most partitioning algorithms are based on the Kernighan-Lin[KER 70] and Fidducia-Mattheyses[FID 82] heuristics with migration groups. These algorithms use a mincut heuristic to decrease the crossing nets between the two blocks, producing saturated regions. Therefore, the nets balancing concept means to search for a balance in the connections size to avoid satured regions, decreasing a computation time and to increase the routing performance. The global vision of automatic synthesis is shown. The main design styles are described and the placement and partitioning problems are analysed. The main features of TRANCA methodology are shown. A summary about the TRANCA synthesis tools is presented, emphasizing the partitioning and placement step in each one. This main features are evaluated. The basic ideas that suported the development of the algorithm are described. The algorithm provides a connection distribuition, using a congestion map of the circuit that describes a global pre-routing. The congestion map is generated based on the circuit partitioning. In addition (to the congestion map), the net paths are defined to control the crossing nets. After the definition of the concepts, the environment created for the algorithm is showed. The most important placement methods are studied and presented in order to provide a general picture of the problem. Among them, specifc attention is given to those based an partitioning. Some particular heuristics are detailed. A prototype system called TRAPP( TRAnsparent Placement by Partitioning) was developed to evaluate this approach. It is completed by a placement viewer, CIPPATO. Finally, some results and conclusions are presented. New implementations and directions for further works are proposed too.

Este trabalho propõe e avalia um novo algoritmo para o posicionamento de células de circuitos que utilizam a metodologia de projeto TRANCA. O algoritmo proposto realiza o posicionamento por particionamento, em n-blocos, baseado no conceito de balanceamento de redes, realizando um pré-roteamento global. A maioria dos algoritmos de posicionamento por particionamento são baseados na heurística de Kernighan-Lin[KER 70] e Fidducia-Mattheyses[FID 82] com migração de grupos. Estes algoritmos utilizam uma função de corte mínimo para diminuir o cruzamento de redes entre as duas partições, produzindo regiões saturadas. Sendo assim, o conceito de balanceamento de redes significa a busca de um equilíbrio no comprimento das conexões para evitar a criação de regiões saturadas, diminuindo o tempo computacional e facilitando a etapa de roteamento. Apresenta-se uma visão geral de síntese automática. Descreve-se os estilos de projeto mais utilizados, define-se e analisa-se o problema de particionamento e posicionamento de células. As principais características da metodologia TRANCA são apresentadas. Resume-se as principais características das ferramentas de síntese TRANCA, destacando-se as etapas de particionamento e posicionamento de cada uma, visando o aproveitamento destas características positivas. Com o propósito de fundamentar os conceitos usados para o desenvolvimento do algoritmo, apresenta-se os métodos de posicionamento mais relevantes, dando destaque aqueles baseados em particionamento. Descreve-se algumas das heurísticas existentes. Os conceitos utilizados para o desenvolvimento do algoritmo são então descritos. O algoritmo consiste basicamente da distribuição das conexões, utilizando um mapa de congestionamento do circuito, o que caracteriza um pré-roteamento global. O mapa de congestionamento é montado sobre as partições geradas no circuito. Além do mapa de congestionamento, a descrição dos caminhos das redes é realizada sobre um modelo definido para controlar o cruzamento de redes. Apos a definição dos conceitos, o ambiente criado para o algoritmo é apresentado. Com o objetivo de validar os conceitos estudados e aqueles propostos, implementou-se um protótipo, chamado TRAPP(TRAnsparent Placement by Partitioning), e um visualizador de posicionamento chamado CIPPATO. Finalmente, alguns resultados do protótipo desenvolvido e uma avaliação sobre o comportamento dente protótipo são apresentados. Propõe também implementações alternativas e direções para trabalhos futuros. / This work proposes and evaluates a new algorithm for cells' placement, for use on TRANCA[REI 87] layouts. The algorithm proposed makes a placement by partitioning using multiple steps, based on the concept of net balancing, in order to make a global prerouting. Most partitioning algorithms are based on the Kernighan-Lin[KER 70] and Fidducia-Mattheyses[FID 82] heuristics with migration groups. These algorithms use a mincut heuristic to decrease the crossing nets between the two blocks, producing saturated regions. Therefore, the nets balancing concept means to search for a balance in the connections size to avoid satured regions, decreasing a computation time and to increase the routing performance. The global vision of automatic synthesis is shown. The main design styles are described and the placement and partitioning problems are analysed. The main features of TRANCA methodology are shown. A summary about the TRANCA synthesis tools is presented, emphasizing the partitioning and placement step in each one. This main features are evaluated. The basic ideas that suported the development of the algorithm are described. The algorithm provides a connection distribuition, using a congestion map of the circuit that describes a global pre-routing. The congestion map is generated based on the circuit partitioning. In addition (to the congestion map), the net paths are defined to control the crossing nets. After the definition of the concepts, the environment created for the algorithm is showed. The most important placement methods are studied and presented in order to provide a general picture of the problem. Among them, specifc attention is given to those based an partitioning. Some particular heuristics are detailed. A prototype system called TRAPP( TRAnsparent Placement by Partitioning) was developed to evaluate this approach. It is completed by a placement viewer, CIPPATO. Finally, some results and conclusions are presented. New implementations and directions for further works are proposed too.

Dissertação (mestrado)—Universidade de Brasília, Centro de Desenvolvimento Sustentável, 2010. / Submitted by Allan Wanick Motta (allan_wanick@hotmail.com) on 2011-05-17T17:42:02Z No. of bitstreams: 1 2010_LauseaniSantoni.pdf: 1503843 bytes, checksum: 0eb4f4653d5986aa6b4bc337c87d08cc (MD5) / Approved for entry into archive by Luanna Maia(luanna@bce.unb.br) on 2011-05-18T13:59:17Z (GMT) No. of bitstreams: 1 2010_LauseaniSantoni.pdf: 1503843 bytes, checksum: 0eb4f4653d5986aa6b4bc337c87d08cc (MD5) / Made available in DSpace on 2011-05-18T13:59:17Z (GMT). No. of bitstreams: 1 2010_LauseaniSantoni.pdf: 1503843 bytes, checksum: 0eb4f4653d5986aa6b4bc337c87d08cc (MD5) / A alocação dos recursos públicos é uma das formas pela qual a política governamental influencia o desenvolvimento regional e social, promove a inclusão social e reduz as desigualdades sociais. O objetivo desta dissertação é discutir a política de saneamento básico e a desigualdade de acesso aos serviços de abastecimento de água e esgotamento sanitário a partir da análise do modelo de financiamento da política pública sob a gestão do Ministério das Cidades. Argumenta-se que esse desenho, que admite a utilização de recursos orçamentários e de empréstimos públicos, pode não gerar incentivos à redução das desigualdades sociais e regionais no acesso aos serviços públicos. Por um lado, os recursos orçamentários, que, por serem a fundo perdido, tenderiam a privilegiar sistemas ou municípios sem viabilidade econômica e financeira, são notadamente marcados pela dispersão em emendas parlamentares. Por outro, o acesso aos empréstimos, proveniente de recursos dos trabalhadores, sob a gestão do Governo Federal, está sujeito a uma série de regras, como o contingenciamento de crédito ao setor público, a capacidade de endividamento do tomador e a análise do risco de crédito. Esses critérios acabam determinando um perfil altamente concentrado da alocação desse tipo de recurso, que beneficiam, principalmente, Estados e municípios da Região Sudeste, com maior desenvolvimento social e econômico e tradicionalmente melhor contemplados pelos serviços da rede de água e esgotos. Em seguida, o estudo apresenta as principais transformações ocorridas na gestão da política federal de 2003 a 2009, mostrando em que medida podem ser identificadas mudanças no padrão de atuação do Governo Federal no setor e no perfil dos investimentos federais em saneamento. A intenção é identificar as principais medidas e estratégias adotadas na formulação, implementação e monitoramento do Programa de Aceleração do Crescimento - PAC. A análise mostra que o Programa ampliou significativamente os recursos disponíveis para investimentos em saneamento, especialmente com fontes orçamentárias, sem, entretanto, reverter as tendências alocatórias dos empréstimos para o setor e sem promover mudanças estruturais das regras e mecanismos do financiamento da política até então vigentes. O trabalho conclui que, apesar das limitações, dada a natureza dos investimentos priorizados pelo PAC, este se consolida não apenas como um Programa destinado a prover infraestrutura, mas, sobretudo, como uma política governamental de inclusão social. Pode ser capaz de reduzir, simultaneamente, a precariedade das condições de habitabilidade da população de baixa renda e a desigualdade regional e social no acesso aos serviços públicos de saneamento básico. Ademais, introduziu alterações significativas no que diz respeito à atuação governamental no setor, especialmente relacionadas a uma visão estratégica, à gestão e ao monitoramento das intervenções apoiadas pela União. _______________________________________________________________________________ ABSTRACT / The allocation of public resources is one of the ways in which government policy influences regional and social development, promote social inclusion and reduce social inequalities. The objective of this dissertation is to discuss the sanitation policy and the unequal access to water supply and sanitation from the analysis of the financing model of public policy under the management of the Ministry of Cities. It is argued that this design, which allows the use of budgetary funds and government loans, may not generate incentives to reduce social and regional inequalities in access to public services. On the one hand, budgetary resources, which, being sunk, would tend to favor systems or municipalities without financial and economic viability, are notably marked by the dispersion in parliamentary amendments. Second, access to loans, from funds of the workers under the management of the Federal Government is subject to a number of rules, such as limited credit to public sector debt capacity of the borrower and the analysis of credit risk . These criteria ultimately determine a profile of highly concentrated allocation of this resource type, which benefit mainly the states and municipalities in the southeast region, with greater social and economic development and better traditionally covered by the services of water mains and sewers. Then, the study presents the main changes in the management of federal policy from 2003 to 2009, showing the extent to which changes can be identified in the pattern of action of the Federal Government in the sector and the profile of federal investments in sanitation. The intention is to identify key measures and strategies adopted in the formulation, implementation and monitoring of the Growth Acceleration Program - PAC. The analysis shows that the program has significantly expanded the resources available for investments in sanitation, especially with budget sources, without, however, reverse the allocation loans trends to the sector and without structural changes to the rules and mechanisms of financing of the hitherto existing. The paper concludes that despite the limitations, given the nature of investments prioritized by the PAC, this consolidates not only as a program intended to provide infrastructure, but mainly as a government policy of inclusion. It may be able to reduce both the precariousness of living conditions of low income and regional inequality, and social access to public sanitation. Moreover, it introduced significant changes in respect to governmental efforts in the sector, especially related to a strategic vision, management and monitoring of operations supported by the Union.

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-03-03T18:22:01Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO_Diego Costa Mendes_PROPAD_2015.pdf: 2191611 bytes, checksum: 6c0936add9c0f3caf76c03be1ccca50a (MD5) / Made available in DSpace on 2016-03-03T18:22:01Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO_Diego Costa Mendes_PROPAD_2015.pdf: 2191611 bytes, checksum: 6c0936add9c0f3caf76c03be1ccca50a (MD5) Previous issue date: 2015-03-05 / FACEPE / Este trabalho trata-se de um estudo qualitativo básico ou genérico, tendo como lócus de pesquisa a comunidade autóctone Engenho Ilha — localizada na região de Suape (PE) —, e propõe compreender como os investimentos do Programa de Aceleração do Crescimento (PAC), direcionados àquela região, implicam na qualidade de vida da população analisada. Esta investigação foi realizada a partir das experiências vividas e da realidade concebida socialmente (MERRIAM, 1998) pelos habitantes da comunidade, juntamente com os dados presentes no 10º Balanço das Atividades do PAC 2 em Pernambuco (BRASIL, 2014) e por relatos de gestores da Empresa Suape e da Secretaria de Planejamento e Gestão do Estado de Pernambuco (Seplag). Por meio de levantamento de dados (coletados mediante observação direta, entrevistas abertas e semiestruturadas, e pesquisa documental) e com base nos conceitos de desenvolvimento (B. SANTOS, RODRÍGUEZ, 2012; FURTADO, 1981, 1973; MADEIRO, 2011), políticas públicas (CARNOY, 1988; HÖFLING, 2011; QUEIROZ, 2009; SOUZA, 2006) e qualidade de vida (MILES, 1996; BUARQUE, 1993; VITTE et al, 2002; JANUZZI, 2006), evidencia-se que a expansão dos empreendimentos e das atividades em Suape, assim como a circulação econômica por ela estimulada, não resulta na melhoria da qualidade de vida dos moradores daquela região. Tais habitantes possuem a significação de suas vidas centrada na terra, e esta mesma terra é o principal alvo das transformações que o Complexo Industrial Portuário de Suape (CIPS) promove na região, as quais são fortemente financiadas com recursos do PAC. O Programa conduz um desenvolvimento hegemônico na região, mas, mesmo possuindo como um de seus objetivos elevar a qualidade de vida da população, a maneira como esses investimentos são alocados não é suficiente para promover a melhoria da qualidade de vida da população analisada. / This work is a basic or generic qualitative study, which research locus is the aboriginal community Engenho Ilha - located in the region of Suape (PE) - and proposes to understand how the investments of the Growth Acceleration Program (PAC) directed to the region, imply the quality of life of the population analyzed. This research was carried out from the experiences and reality socially designed (MERRIAM, 1998) by community members, along with the data present on the 10th Overview of the PAC Activities 2 in Pernambuco (BRASIL, 2014) and managers reports Suape company and the Department of Planning and State of Pernambuco Management (Seplag). Through survey data (collected through direct observation, open and semi-structured interviews and documentary research) and based on the concepts of development (B. SANTOS, RODRÍGUEZ, 2012; FURTADO, 1981, 1973; MADEIRO, 2011), public policies (CARNOY, 1988; HOFLING, 2011; QUEIROZ, 2009; SOUZA, 2006) and quality of life (MILES, 1996; BUARQUE, 1993; VITTE ET AL, 2002; JANUZZI, 2006), it is clear that the expansion of enterprises and the activities in Suape, as well as the economic circulation stimulated by it, does not result in improving the quality of life of that region residents. Those people have the significance of their lives centered on the land, and this land is the main aim of the changes that the Industrial Port Complex of Suape (CIPS) promotes in the region, which are heavily financed with PAC resources. The Program conducts an hegemonic development in that region, but despite having as one of its objectives to raise the population's quality of life, the way these investments are allocated is not enough to promote the improvement of the quality of life of the population analyzed.

Multivariate Gaussians: We provide sample complexity upper bounds for semi-agnostically learning multivariate Gaussians under the constraint of approximate differential privacy. These are the first  finite sample upper bounds for general Gaussians which do not impose restrictions on the parameters of the distribution. Our bounds are near-optimal in the case when the covariance is known to be the identity, and conjectured to be near-optimal in the general case. From a technical standpoint, we provide analytic tools for arguing the existence of global "locally small" covers from local covers of the space. These are exploited using modifications of recent techniques for for differentially private hypothesis selection. Mixtures of Gaussians: We consider the problem of learning mixtures of Gaussians under the constraint of approximate differential privacy. We provide the first sample complexity upper bounds for privately learning mixtures of unbounded axis-aligned (or even unbounded univariate) Gaussians. To prove our results, we design a new technique for privately learning mixture distributions. A class of distributions F is said to be list-decodable if there is an algorithm that, given "heavily corrupted" samples from a distribution f in F, outputs a list of distributions, H, such that one of the distributions in H approximates f. We show that if F is privately list-decodable then we can privately learn mixtures of distributions in F. Finally, we show axis-aligned Gaussian distributions are privately list-decodable, thereby proving mixtures of such distributions are privately learnable. / Thesis / Master of Science (MSc) / Is it possible to estimate an unknown probability distribution given random samples from it? This is a fundamental problem known as distribution learning (or density estimation) that has been studied by statisticians for decades, and in recent years has become a topic of interest for computer scientists. While distribution learning is a mature and well understood problem, in many cases the samples (or data) we observe may consist of sensitive information belonging to individuals and well-known solutions may inadvertently result in the leakage of private information. In this thesis we study distribution learning under the assumption that the data is generated from high-dimensional Gaussians (or their mixtures) with the aim of understanding how many samples an algorithm needs before it can guarantee a good estimate. Furthermore, to protect against leakage of private information, we consider approaches that satisfy differential privacy — the gold standard for modern private data analysis.

Nesse trabalho foram produzidas nanopartículas (NPs) de Gd2O3 e Er2O3 para aplicação como radiossensibilizadores em feixes de radioterapia. Elas foram sintetizadas no Laboratório de Interações Hiperfinas do IPEN pelo método da decomposição térmica e caracterizadas utilizando difração de raios-X, para verificar a estrutura cristalina, microscopia eletrônica de transmissão, para obter informações sobre forma, tamanho e distribuição de tamanho, análise por ativação neutrônica, por meio da qual foi possível determinar a pureza das amostras e calcular a concentração de gadolínio e érbio. Medições de magnetização e de espectroscopia de correlação angular γ-γ perturbada (PAC) foram realizadas a fim de estudar o comportamento magnético e a interação quadrupolar das partículas, respectivamente. Os resultados da caracterização mostram a formação de uma estrutura cristalina do tipo bixbyite, com aproximadamente 5 nm de diâmetro e estreita distribuição de tamanho, para as amostras pós-síntese. A determinação da massa de terra-rara em cada amostra foi importante para realizar a normalização nas medições de susceptibilidade magnética, tornando possível a visualização de um grande aumento na magnetização abaixo de 30 K, nas amostras pós-síntese, o que não é observado em partículas maiores, além de um aumento no momento magnético efetivo das NPs em relação aos respectivos bulks e uma mudança na temperatura de ordenamento antiferromagnético para o Er2O3. Os resultados da espectroscopia PAC evidenciam possíveis efeitos de superfície. A falta de uma frequência bem definida nas amostras de 5 nm indicam que a quantidade de 111In(111Cd) na superfície da partícula é maior do que no interior da mesma, fazendo com que a interação hiperfina do núcleo de prova com o host não seja evidente. Já a união da técnica de difração de raios-X com a espectroscopia PAC foi fundamental para o entendimento do dano causado às partículas pela irradiação com 60Co. Quanto às medições de radiossensibilização a dosimetria Fricke gel foi fundamental para a verificação de um fator de aumento de dose (DEF) de até 1,67 e 1,09 para NPs de Gd2O3 irradiadas com 60Co e 6MV, respectivamente. Nas mesmas condições, para as amostras de Er2O3, foram encontrados valores de DEF de até 1,37 e 1,06. Isso comprova os efeitos radiossensibilizadores dessas NPs. Os resultados alcançados nesse trabalho não apenas fornecem dados importantes para o estudo de NPs de terra-rara na área de física da matéria condensada como também uma base sólida para a aplicação desses elementos como radiossensibilizadores em feixes de radioterapia, possibilitando a utilização da imagem por ressonância magnética para localizar e obter a concentração dessas NPs dentro do paciente, aumentando assim a eficiência do tratamento do câncer. / In this study Gd2O3 and Er2O3 nanoparticles were produced for application as radiosensitizers in radiotherapy beams. They were synthesized at the Hyperfine Interactions Laboratory, IPEN, using thermal decomposition method and characterized by X-ray diffraction, to verify crystalline structure, transmission electron microscopy, to obtain information about shape, size and size distribution, neutron activation analysis, whereby it was possible to determine samples purity and gadolinium and erbium concentration. Magnetization and perturbed γ-γ angular correlation (PAC) measurements were performed in order to study particles magnetic behavior and quadrupole interactions, respectively. Characterization results showed a bixbyite structure, 5 nm diameter post-synthesis particles with narrow size distribution. Rare-earth mass determination in each sample was important to perform normalization in magnetic susceptibility measurements, making possible the view of a high magnetization under 30 K for post-synthesis samples, what was not observed in larger particles, together with an effective magnetic moment enhancement for nanoparticles, not seen in bulk samples, and a change in the antiferromagnetic ordering temperature for Er2O3. PAC spectroscopy results show possible surface effects. The absence of a well-defined frequency in 5 nm samples indicates the amount of 111In(111Cd) at particle surface is bigger than in the core, resulting in a non-evident hyperfine interaction between the probe nuclei and the host. The X-ray diffraction and PAC spectroscopy joint was vital to understand the particles structural damage caused by 60Co irradiation. About radiosensitizer measurements a dose enhancement factor (DEF) of up to 1,67 and 1,09 for Gd2O3 nanoparticles under 60Co and 6MV irradiation, respectively, were observed. Under same conditions DEF values of up to 1,37 and 1,06 were found for Er2O3 samples. Results reached in this study provide not only important data for rare-earth oxides study in condensed matter physics but also a solid ground for the application of these elements as radiosensitizers in radiotherapy beams, allowing the use of magnetic resonance imaging to locate and obtain the concentration of these particles inside patient body, increasing cancer treatment efficiency.