O sucesso dos Sistemas de Gerenciamento de Banco de Dados (SGBDs) em aplicações envolvendo dados tradicionais (números e textos curtos) encorajou o seu uso em novos tipos de aplicações, que exigem a manipulação de dados complexos. Séries temporais, dados científicos, dados multimídia e outros são exemplos de Dados Complexos. Inúmeras áreas de aplicação têm demandado soluções para o gerenciamento de dados complexos, dentre as quais a área de informática médica. Dados complexos podem também ser estudos com técnicas de descoberta de conhecimentos, conhecidas como KDD (Knowledge Discovery in Database), usando alguns algoritmos de detecção de agrupamentos apropriados. Entretanto, estes algoritmos possuem custo computacional elevado, o que dificulta a sua utilização em grandes conjuntos de dados. As técnicas já desenvolvidas na Área de Bases de Dados para indexação de espaços métricos usualmente consideram o conjunto de maneira uniforme sem levar em conta a existência de agrupamentos nos dados, por isso as estruturas buscam maximizar a eficiência das consultas para todo o conjunto simultaneamente. No entanto muitas vezes as consultas por similaridade estão limitadas a uma região específica do conjunto de dados. Neste contexto, esta dissertação propõe a criação de um novo método de acesso, que seja capaz de indexar de forma eficiente dados métricos, principalmente para conjuntos que contenham agrupamentos. Para atingir esse objetivo este trabalho também propõe um novo algoritmo para detecção de agrupamentos em dados métricos tornando mais eficiente a escolha do medoide de determinado conjunto de elementos. Os resultados dos experimentos mostram que os algoritmo propostos FAMES e M-FAMES podem ser utilizados para a detecção de agrupamentos em dados complexos e superam os algoritmos PAM, CLARA e CLARANS em eficácia e eficiência. Além disso, as consultas por similaridade realizadas com o método de acesso métrico proposto FAMESMAM mostraram ser especialmente apropriados para conjuntos de dados com agrupamentos / The success of Database Management System (DBMS) for applications with traditional data (numbers and short texts) has encouraged its use in new types of applications that require manipulation of complex data. Time series, scientific data and other multimedia data are examples of complex data. Several application fields, like medical informatics, have demanded solutions for managing complex data. Complex data can also be studied by means of Knowledge Discovery Techniques (KDD) applying appropriate clustering algorithms. However, these algorithms have high computational cost hindering their use in large data sets. The techniques already developed in the Databases research field for indexing metric spaces usually consider the sets have a uniform distribution, without taking into account the existence of clusters in the data, therefore the structures need to generalize the efficiency of queries for the entire set simultaneously. However the similarity searching is often limited to a specific region of the data set. In this context, this dissertation proposes a new access method able to index metric data efficiently, especially for sets containing clusters. It also proposes a new algorithm for clustering metric data so that selection of a medoid from a particular subset of elements becomes more efficient. The experimental results showed that the proposed algorithms FAMES and M-FAMES can be used as a clustering technique for complex data that outperform PAM, CLARA and CLARANS in effectiveness and efficiency. Moreover, the similarity searching performed with the proposed metric access method FAMESMAM proved to be especially appropriate to data sets with clusters

No description available.

O objetivo deste trabalho foi determinar a massa do aglomerado de galáxias RXC J1504-0248, localizado em z = 0.215, através da análise de lentes fracas, e comparar os resultados com aqueles obtidos em trabalhos anteriores através da análise de raios-X. Imagens do aglomerado foram obtidos nas bandas r\', g\' e i\' com o detector GMOS do telescópio Gemini Sul. A partir dessas imagens, contruímos um catálogo de objetos no campo usando o software Sextractor (SE) (Bertin e Arnouts, 1996). Este software também foi utilizado para classificá-los como galáxias ou estrelas. Foram identificadas 172 galáxias neste campo, que também foram detectadas no Data Release 7 do Sloan Digital Sky Survey (SDSS). Estas galáxias foram então usadas para obter uma calibração fotométrica das imagens, comparando as magnitudes instrumentais e do SDSS nas mesmas bandas. Após a calibração fotométrica, e através da comparação com imagens do CFHTLS obtidas em cores semelhantes, as galáxias foram classificadas como membros de cluster, foreground ou background, a partir de sua posição nos diagramas cor-cor e cor-magnitude. A reconstrução da massa do aglomerado através da análise de lentes gravitacionais foi realizada em duas etapas. Na primeira, foi utilizado o software IM2SHAPE, desenvolvido por Bridle et al. (1998), que modela os objetos, adicionando até três gaussianas, cada uma definida por seis parâmetros: as coordenadas do centro do objeto, x0 e y0, a elipticidade e, o ângulo de posição , o produto dos semi-eixos maior e menor ab, e a amplitude A. Inicialmente, o programa foi executado apenas para as estrelas do campo, com o objetivo de se obter uma estimativa da distribuição da PSF. A estimativa foi então utilizado como entrada para a análise das galáxias. Na segunda etapa, para estimar a massa do aglomerado foi utilizado o programa LENSENT, desenvolvido por Marshall et al. (2002), cujos parâmetros de entrada são a elipticidade das galáxias de fundo e seus erros. Na técnica de lentes gravitacionais fracas, a dependência radial da deformação das galáxias de fundo permite determinar o perfil de massa do aglomerado. Para estimar a massa, ajustamos um perfil de uma Esfera Isotérmica Singular (SIS, na sigla em inglês), e determinamos o valor da massa dentro de um raio de 3Mpc, 1.3 ± 0.6 x 10¹ Msol. O resultado é consistente com o obtido por Bohringer et al., 2005, 1.7 x 10¹ Msol, através da análise em raios-X. Comparando o mapa de distribuição de luminosidade e da emissão de raios-X concluímos que eles são muito semelhantes à distribuição superficial de massa, resultado que indica equilíbrio. / In this work we studied the galaxy cluster RXC J1504-0248, at z=0.215, from images in the bands r\', g\' and i\' obtained with Gemini South telescope. The photometric calibration was performed by comparison with field objects identified in the Sloan Digital Sky Survey (SDSS). From the analysis of color-color and color-magnitude diagrams, galaxies in the field were then divided into cluster members, background and foreground objects. We determined the PSF using the IM2SHAPE program \\cite{Bridle98}. These results enabled us to obtain the cluster projected mass distribution through a weak lensing analysis performed with the LENSENT program \\cite{Marshall02}. We also shown that the cluster luminosity distribution and the X-ray emission are consistent with the mass map. Using a SIS model, we estimated the mass of the cluster, obtaining 1.3 x 10¹ Msun, consistent with the mass obtained in a previous X-ray analysis, 1.7 x 10¹ Msun, by \\cite{Bohringer05}.

包含少於1000 個原子的金屬納米顆粒會與此金屬的常規尺寸材料有很大差別。它們擁有一些特殊的物理和化學的性質，因而在過去的二十年中吸引了大量的研究工作。但是由於尺寸太小，對於這些納米結構的深入和全面的研究十分困難。掃描隧道顯微鏡方法是一種強大的研究此類問題的技術。它擁有的極強的空間分辨力和原子操縱的能力使得我們可以獲得一些納米顆粒的細緻信息。在這篇論文中，我將報道我的關於在半導體Si(111)-(7x7)的重構表面的貴金屬（銀/金）顆粒的研究。 / 我首先研究了在Si(111)-(7x7)上的金屬顆粒的製備方法。使用熱蒸發方法，我製備了在Si(111)-(7x7)上的金屬顆粒。在研究了這些金屬顆粒在半元胞中的的整體生長過程之後，我的研究集中在本論文的主要目標--獨立的銀納米顆粒上。通過仔細觀察記錄單個銀原子的擴散過程，我們確認了Ag3‐Ag13 顆粒中的原子數目。這些掃描隧道顯微鏡的圖像同時也指出了這些顆粒的動態性質，包括自發跳動、分解和與鄰近的單個Ag 原子的合成。為了獲得對這些Ag 顆粒的控制，我們找到了一種垂直操縱單個Ag 原子的方法。在樣品的表面，掃描隧道顯微鏡的針尖通過特定的程序被用來抓起和放下單個Ag 原子。它被用來組裝和拆裝Ag的顆粒。各種Ag 顆粒在半元胞中被組裝，同時我們發現單個半元胞中的最大的顆粒是Ag25。同時這項技術被用來組裝複雜的Ag 顆粒的圖形。 / 使用上面這些操縱的技術（熱蒸發方法和原子操縱方法），我們細緻的研究了顆粒的兩方面性質：第一，我們發現對於單個元胞中的Ag 顆粒都存在着顯著的電學的整流效應，同時我們比較了它們各自的特點。通過實驗測量和第一性原理計算，我們發現這種電學整流效應源自電子態密度的耦合效應。當這些顆粒在平面內連接起來從而增加橫向的尺寸時，這種顆粒的整流效應將會繼續存在；但當顆粒形成多層Ag 的結構即垂直方向尺寸增加時，這個整流效應將會消失。另外一個所研究的性質是所有的Ag顆粒都存在一種對周圍單個Ag原子的吸引作用，從而讓自身長大的過程。這一過程對於Ag 顆粒的生長起到了至關重要的作用。我們選擇了幾個有代表性的顆粒，通過原子操縱的方法測量了它們與一個鄰近的Ag 原子的融合過程。測量的結果說明一個顆粒的存在通常會降低一個鄰近Ag 原子向此顆粒擴散的勢壘高度，同時也會影響此單個原子在靠近此顆粒的吸附位上的吸附能。 / Metal nanoclusters with less than 1000 atoms differ very much from their bulk counterparts. They possess many unique chemical and physical properties and have attracted extensive studies during the past two decades. However, in-depth and comprehensive researches of these structures are difficult for their small size. Scanning tunneling microscopy (STM) is a versatile technique to study the nanostructures. Its extreme powerful spatial resolution as well as its atomic manipulation capability enabled us to obtain the detailed information of some nano-clusters. In this thesis, I report on my studies on the noble metal (mainly Ag) clusters on the reconstructed Si(111)-(7x7) surface. / I firstly studied the fflbrication methods of the metal clusters on the Si(111)-(7x7) surface. By thermal deposition, I fabricated Ag clusters on Si(111)-( 7x7). After studying the overall growth process of the Ag clusters in half unit cells, I focused on the main target of this thesis: individual Ag clusters. By carefully observing the diffusion process of the Ag atoms on the surface, we identified of the number of atoms inside Ag3-Ag13 clusters. The STM images also showed the dynamic behaviors of each cluster, including self-hopping, dissociation and association with nearby Ag atoms. For a better controllability, a vertical manipulation technique was developed to transfer single Ag atoms across difference locations on the Si(111)-(7x7) surface. The STM tip was used to pick up or drop off metal atoms from or to the sud"ace following specific procedures. The assembly and disassembly of Ag clusters were achieved by this method. Various Ag clusters were built and the largest occupation of a FRUC was found to be 25 Ag atoms. This technique was demonstrated to be able to manipulate Au atoms and to assemble Au clusters. / With the developed fabrication methods, by thermal deposition as well as by atomic manipulation, two properties of the clusters were studied carefully: first, a prominent electrical rectifying behavior was observed for all the Ag clusters. Their individual behaviors were compared with each other. A combination of experimental measurements and first principle calculations unveiled the mechanism of the electronic rectifying behaviors to be a wave function coupling effect. The rectifying behavior for the clusters was found to persist when clusters connected laterally, whereas to disappear when the vertical size of the cluster increased to form multiple Ag layers. The second property studied is that all the clusters are found to attract nearby single Ag atoms to grow larger. This behavior plays a critical role in the growth process of the Ag clusters. we chose several typical Ag clusters and measured the merging process with single neighboring Ag atoms by atomic manipulation. The results indicate that the presence of a Ag cluster will mostly reduce the diffusion barrier of a single Ag atom in the neighboring half unit cells to diffuse to the cluster and even affect / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Ming, Fangfei = 在Si(111)-(7x7)表面的金屬納米顆粒的製備和性質 / 明方飛. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 116-122). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Ming, Fangfei = Zai Si(111)-(7x7) biao mian de jin shu na mi ke li de zhi bei he xing zhi / Ming Fangfei. / Chapter 1 --- Introduction: metal nano-clusters on semiconductor surfaces --- p.2 / Chapter 1.1 --- Background and Motivation --- p.2 / Chapter 1.1.1 --- Nano-science and nano-technology --- p.2 / Chapter 1.1.2 --- Metal nano-clusters --- p.3 / Chapter 1.2 --- Scanning tunneling microscopy (STM) --- p.6 / Chapter 1.2.1 --- Introduction to STM --- p.6 / Chapter 1.2.2 --- Basic components of STM --- p.7 / Chapter 1.2.3 --- STM working modes --- p.9 / Chapter 1.2.4 --- STM experiments in this thesis --- p.11 / Chapter 1.3 --- Substrate: the Si(111)-(7 x 7) reconstruction surface --- p.12 / Chapter 1.3.1 --- Atomic Structure --- p.12 / Chapter 1.3.2 --- Preparation in ultra high vacuum --- p.14 / Chapter 1.4 --- Growth of Ag on Si(111)-(7 x 7) at room temperature --- p.14 / Chapter 1.4.1 --- Growth method --- p.15 / Chapter 1.4.2 --- Adsorption and diffusion of single Ag atoms --- p.17 / Chapter 1.4.3 --- Forming Ag clusters --- p.20 / Chapter 1.4.4 --- Forming Ag islands --- p.23 / Chapter 1.5 --- Conclusion --- p.25 / Chapter 2 --- Individual Ag clusters: size, dynamics and stability --- p.27 / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Experiment --- p.29 / Chapter 2.3 --- Results and discussion --- p.31 / Chapter 2.3.1 --- Growth kinetics --- p.31 / Chapter 2.3.2 --- STrvr images of typical Ag structures Intra-HUC diffusion --- p.33 / Chapter 2.3.3 --- Inter-HUC diffusion --- p.37 / Chapter 2.3.4 --- Inter-HUC diffusion & identification of the number of atoms inside each cluster --- p.38 / Chapter 2.3.5 --- Stability of Ag structures. --- p.45 / Chapter 2.4 --- Conclusion --- p.49 / Chapter 3 --- Assembling and disassembling Ag/ Au clusters by atomic manipulation --- p.51 / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.2 --- Experiment --- p.54 / Chapter 3.3 --- Results and disscussion --- p.55 / Chapter 3.3.1 --- Basic procedures for manipulating a single Ag atom --- p.55 / Chapter 3.3.2 --- Assembly of Ag clusters --- p.58 / Chapter 3.3.3 --- Disassembly of Ag clusters --- p.66 / Chapter 3.3.4 --- Assembly of Ag cluster patterns --- p.70 / Chapter 3.3.5 --- Comparison with the manipulation of Au atoms --- p.71 / Chapter 3.3.6 --- STrvr tip for atomic manipulation --- p.74 / Chapter 3.4 --- Conclusion --- p.75 / Chapter 4 --- Study on the electronic properties of the Ag clusters --- p.76 / Chapter 4.1 --- Introduction --- p.76 / Chapter 4.2 --- Experiment --- p.78 / Chapter 4.2.1 --- Experimental parameters. --- p.78 / Chapter 4.2.2 --- Precise tip positioning --- p.79 / Chapter 4.2.3 --- First principle calculation parameters --- p.80 / Chapter 4.3 --- Results and Discussion --- p.81 / Chapter 4.3.1 --- Grow Ag clusters --- p.81 / Chapter 4.3.2 --- I-V of the clusters. --- p.82 / Chapter 4.3.3 --- Theoretical calculation --- p.88 / Chapter 4.3.4 --- Transition from cluster to bulk in I-V. --- p.91 / Chapter 4.4 --- Conclusion --- p.94 / Chapter 5 --- Dynamics of Ag atoms near an interacting Ag cluster --- p.95 / Chapter 5.1 --- Introduction --- p.95 / Chapter 5.2 --- Results and Discussion --- p.97 / Chapter 5.2.1 --- Different Ag clusters and their orientations --- p.97 / Chapter 5.2.2 --- Association time measurement --- p.99 / Chapter 5.2.3 --- Energy barrier and diffusion prefactor --- p.101 / Chapter 5.2.4 --- Influenced intra-HUC diffusion --- p.105 / Chapter 5.2.5 --- Energy diagram --- p.107 / Chapter 5.3 --- Conclusion --- p.109 / Chapter 6 --- Conclusion and Future Work --- p.111 / Chapter 6.1 --- Conclusion --- p.111 / Chapter 6.2 --- Future work --- p.113 / Bibliography --- p.116

Submitted by Ana Paula Lisboa Monteiro (monteiro@univates.br) on 2012-06-18T17:21:13Z No. of bitstreams: 3 JoaoCarpes.pdf: 43995252 bytes, checksum: 4f5471e022b7097f90caa5f9106f43ca (MD5) license_rdf: 23599 bytes, checksum: 9e2b7f6edbd693264102b96ece20428a (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2012-06-18T17:21:13Z (GMT). No. of bitstreams: 3 JoaoCarpes.pdf: 43995252 bytes, checksum: 4f5471e022b7097f90caa5f9106f43ca (MD5) license_rdf: 23599 bytes, checksum: 9e2b7f6edbd693264102b96ece20428a (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / A economia do município de Farroupilha/RS, historicamente, esteve centralizada no setor primário. Contudo, a partir da década de 1970, passou também a se voltar para a atividade industrial. Isso porque surgiu, por parte da administração municipal daquela época, uma política de desenvolvimento industrial, que concedeu incentivos à instalação de indústrias em distritos industriais. A presente dissertação buscou analisar as repercussões socioambientais decorrentes da criação do primeiro distrito industrial do Rio Grande do Sul, no município de Farroupilha, em 1969, verificar a implementação da gestão ambiental do município e por fim, analisar se a legislação contemporânea exige licenciamento ambiental para tais empreendimentos. Para tanto, foi adotado o método qualitativo, por meio de pesquisa bibliográfica e documental no exame da legislação ambiental nas esferas federal, estadual e municipal, bem como utilização de entrevistas semiestruturadas. No momento da instalação do distrito industrial, não havia previsão legal exigindo licenciamento ambiental, quer seja do próprio distrito, quer seja das empresas que foram instaladas, posto que a criação do distrito ocorreu em 1969 e a lei que o exige foi publicada em 1981. No período de sua instalação, a preocupação dos gestores públicos foi com a promoção do crescimento econômico, o qual foi alcançado. Em conseqüência desse progresso, ocorreram relevantes repercussões socioambientais, tanto positivas, quanto negativas. Dentre os aspectos positivos estão o incremento na geração de empregos e na arrecadação, o desenvolvimento do empreendedorismo local e o avanço no nível de instrução da população, bem como a miscigenação cultural. Já o surgimento de novos loteamentos habitacionais sem a devida infraestrutura, o abalo à segurança municipal, o aumento no consumo de matérias-primas e a alteração na flora e fauna locais foram apontados como alguns dos impactos negativos do distrito.

Les pôles de compétitivité sont des institutions publiques dont la mission est de favoriser les synergies entre des acteurs hétérogènes. Ils sont régulièrement soumis à des évaluations dont l’objet est la mesure de leur efficacité. Si les pôles ont la capacité de faire émerger des projets collaboratifs innovants, les pouvoirs publics ont toutefois souligné leurs difficultés à transformer ces efforts collaboratifs en création d’emplois et en croissance sur le territoire. La très grande majorité des entreprises membres sont des PME ; il est reconnu que le dirigeant de PME constitue une figure centrale de son entreprise. Dès lors nous nous demandons comment améliorer l’accompagnement de ces dirigeants afin de faire des projets collaboratifs des générateurs d’emplois et de croissance sur le territoire. Dans la littérature en entrepreneuriat, il est établi que les dirigeants de PME en capacité d'identifier des opportunités puis de les exploiter vont insuffler une dynamique de croissance à leur entreprise. En effet, l'organisation, au travers de son infrastructure cognitive, offre les conditions nécessaires à ses membres pour une meilleure perception des opportunités. En retour, la poursuite de l'opportunité identifiée bénéficiera à la structure qui pourra se développer et donc contribuer à générer de la croissance et de l'emploi. Au regard de ces premiers éléments nous établissons un premier modèle conceptuel qui vise à déceler les antécédents de l’identification d’opportunités d’affaires ; il est testé à partir de 205 questionnaires de dirigeants de PME membres des pôles de compétitivité, à l’aide de la méthode des équations structurelles. L’étude exploratoire menée auprès de huit institutionnels contribuant au fonctionnement des pôles et de dix membres adhérents met par ailleurs en évidence le cas particulier des dirigeants de PME participants à un projet collaboratif. Ainsi, un second modèle spécialement dédié à cette population souligne l’influence de la nature des relations entretenues au sein de ces projets et leur influence sur l’identification d’opportunités d’affaires. Des analyses menées grâce à la méthode des régressions linéaires multiples sont ainsi réalisées sur un échantillon de 100 dirigeants de PME participants à un projet collaboratif. Notre objectif est de mettre en lumière les antécédents de l'identification d'opportunités d'affaires afin de permettre aux pôles de mieux accompagner les dirigeants de PME. En soutenant la phase d'identification, les pôles de compétitivité pourront favoriser la transformation des efforts collaboratifs en emplois et croissance sur le territoire. Les résultats font ressortir le rôle prégnant de la recherche d’informations relatives au marché dans l’identification d’opportunités d’affaires. De plus, la nature des relations qu’entretiennent les participants à un projet collaboratif influence également fortement la capacité des dirigeants de PME à identifier ces opportunités. Ces éléments soulignent la nécessité pour les pôles de compétitivité de repenser leur rôle d’intermédiaire des échanges pour établir les conditions favorables à l’identification d’opportunités d’affaires ; des propositions sont faites en ce sens. / The French clusters are partnerships born out of the wish of public policies to make various actors (such as large and small firms, research bodies and educational establishments) working all together in a specific region to develop synergies and cooperative efforts around a shared theme. They are subject to regular assessments to measure their effectiveness. Their ability to bring out innovative and collaborative projects is recognized but the authorities stressed their difficulties in transforming these collaborative efforts in job creation and growth in the territory. Most of the corporations that belong to French clusters are SMEs and it is well-known that the SME’s manager is a central figure in his business. Therefore, we wonder how the French clusters can improve the support of these leaders in order to help them converting collaboration projects into job creation and growth. In the entrepreneurship literature, it is established that the SME’s manager ability to identify business opportunities and exploit them will create a dynamic for the economic growth of the organization. Indeed, the organization provides - through its knowledge structure - the necessary conditions to a better perception of opportunities. In return, the exploitation of the opportunity will benefit to the structure, favor its development and generate employment and growth. In this context, we build a first conceptual model aiming to identify the antecedents of business opportunity identification. The data were collected through a questionnaire answered by 205 SMEs managers belonging to a French cluster and was analyzed by Structural Equation Modeling (Amos). The exploratory qualitative study was conducted with 8 institutional actors managing the French clusters and 10 SMEs’ managers members of these clusters and reveal the particular case of SMEs managers participating in a collaborative project. Thus, a second model specially dedicated to this subpopulation (100 SMEs managers participating in a collaborative project) is run. We use multiple regression analysis to explore the nature of relationships within these projects and their influence on the identification of business opportunities. By highlighting the antecedents of business opportunity identification, our objective is to give the French clusters the necessary tools to better support the SMEs’ managers and thus favor the transformation of synergies into growth and job creation. The results highlight the significant role of market information research in the identification of business opportunities. Moreover, the nature of the relationship between the participants in a collaborative project also strongly influences the ability of SMEs managers to identify these opportunities. These factors underscore the need for clusters to rethink their role as a medium of exchange to establish the conditions for the identification of business opportunities. Proposals are made in this direction.

Solving the cooling flow problem in cool-core galaxy clusters is critical to under- standing the largest structures in the universe. In addition, cool-core systems are the only places where we have observed direct evidence of AGN feedback, and thus provide the unique opportunity to test models of AGN feedback and various other physical processes. In this thesis we study the influence of momentum-driven AGN feedback on cool-core clusters using high-resolution adaptive mesh refinement (AMR) simulations. We find that run-away cooling first happens only in the central 50 pc region while no local instability develops outside the very center of the cluster. The gas is accreted onto the super-massive black hole (SMBH) which powers AGN jets at an increasing rate as the entropy continues to decrease in the core. The ICM first cools into clumps along the propagation direction of the AGN jets due to the non-linear perturbation. As the jet power increases, gas condensation occurs isotropically, forming spatially extended (up to a few tens kpc) structures that resemble the observed Hα filaments in Perseus and many other cool-core cluster. Jet heating elevates the gas entropy and cooling time, halting clump formation. The cold gas that is not accreted onto the SMBH settles into a rotating disk. In the last few Gyr, the ICM cools onto the disk directly while the innermost region of the disk continues to accrete onto the SMBH, powering the AGN jets to achieve a thermal balance. The mass cooling rate averaged over 7 Gyr is &sim 30 solarmass/yr, an order of magnitude lower than the classic cooling flow value (which we obtain in runs without the AGN). Owing to its self-regulating mechanism, AGN feedback can successfully balance cooling with a wide range of model parameters. Besides suppressing cooling, our model produces cold structures in early stages (up to &sim 2 Gyr) that are in good agreement with the observations. However, the long-lived massive cold disk is unrealistic, suggesting that additional physical processes are still needed. Our recent investigation shows that star formation may play an important role.

In this Dissertation we explore how the nature of tidal interactions tear gravitationally bound systems apart into distinct morphological and kinematic structures. We use the properties of these structures, persisting for billions of years, to investigate the potential of the Milky Way Galaxy and to disentangle the baryonic evolution of gas in dwarf galaxy interactions. We approach these problems through a combination of observations, and simulations, as well as comparisons between the two. In particular, we use the properties of the thin, curved stellar stream emerging from the old, Milky Way globular cluster, Palomar 5 (Pal 5) to show that its mere existence can rule out a moderately triaxial potential model of our Galaxy. Pal 5-like streams on appropriate orbits diffuse much further in space from the orbital path (dubbed “stream-fanning”) in this triaxial potential than in the oblate case. We further show that torques from the Milky Way’s Galactic bar, can create ever-widening gaps in stellar streams. The fact that the bar can create such under densities, demonstrates that we should be careful when interpreting gaps in stellar streams as indirect evidence of the existence of dark matter subhalos in our Galaxy. We carry out a systematic study of resolved neutral hydrogen (HI) synthesis maps of 10 interacting dwarf galaxy pairs. The pairs are located in a range of environments and captured at various interaction stages. We find that the neutral gas is extended in the interacting pairs when compared to non-paired analogs, indicating that gas is tidally pre- processed. Additionally, we find that dwarf-dwarf interactions enable the “parking” of gas at large distances to serve as a continual gas supply channel to the dwarfs until accretion by a more massive host. We model a specific dwarf pair in our sample, NGC 4490/85, which is an isolated analog of the Magellanic Clouds and is surrounded by a ∼50 kpc extended HI envelope. We use hybrid N-body and test-particle simulations along with a visualization interface to simultaneously reproduce the observed present-day morphology and kinematics. Our numerical results con- firm that encounters between two dwarf galaxies can “park” baryons at very large distances, without the aid of environmental effects. The extended tidal features will continue to evolve over several billion years which will affect the efficiency of gas stripping if such dwarf pairs are accreted by a massive host. In contrast, in isolated environments dwarf-dwarf interactions can create a long-lived supply mode of gas to the merger remnant potentially explaining the population of dwarfs in the field with large gas envelopes, but limited star formation. All of these topics share the common theme of utilizing morphological and kinematic structures left behind from ongoing gravitational interactions on various scales.

Thin nanoporous films are attractive for many potential uses for example gas separation, catalysis, filtration of viruses, ore flotation, or as low-dielectric-constant materials. Zeolite and mesoporous materials are the two important nanoporous material classes. In this thesis, we synthesized and characterized two different thin nanoporous films; (i) mesostructured films at the mica-solution interface; (ii) mechanical exfoliated zeolites. The mesoporous materials are well-defined pore shoe and size, and exhibit various morphologies, such as thin films, etc. In contrast, zeolites are a kind of perfect crystal and the morphologies are strongly related to their structures and are difficult to control. Therefore, first we synthesis mesostructured films at mica-solution interface in acidic solution. In-situ Atomic Force Microscopy (AFM) has been used to reveal the formation process of organic and inorganic mesophase films at the molecular level. Then, we synthesized two-dimensional zeolite structures via mechanical exfoliation process that does not involve any chemical intervention and can be applicable to a wide variety of structures with different chemical makeup. Three different zeolite structure nanosheets related to the structure code MWW, UTL, and MFI have been prepared. AFM and TEM have been used to characterized the exfoliated single nanosheet. In order to broaden the application of the single zeolite nanosheet, platinum nano-clusters are encapsulated within mechanical exfoliated zeolite MFI nanosheets by ion exchange from aqueous solution of [Pt(NH3)4](NO3)2. High-angle annular dark field scanning transmission electron microscopy has been used to indicate the Pt clusters in the zeolite MFI structures. Because of the property of the mechanically as-synthesised exfoliated MFI nanosheets that is the long hydrocarbon chains are essentially intact on both sides of the inorganic layer, and can prevent thickening of the zeolite MFI nanosheets along b-axis, we use the mechanically exfoliated MFI as seeds for further growth to form large scale MFI membrane with uniform nano-thickness. Encapsulating noble metals within the channels or cavities of zeolites has already drawn numerous attentions because the well-defined zeolite structure is able to constrain the metal nanoparticle (NPs) aggregation size and enhance the diversity and activity for catalysis. We use the organic surfactant (C22-6-6Br2) and [Pt(NH3)4](NO3)2 as the structure and metal precursor to form Pt-containing nanowires; and use F- to inhibit the premature precipitation of Pt precursors. After involving F-, the Pt-containing nanowire structures were generated.

The oldest open clusters within 250 pc of the Sun, the Hyades and Praesepe, are important benchmarks for calibrating stellar properties such as rotation and magnetic activity. As they have the same age and roughly solar metallicity, these clusters serve as an ideal laboratory for testing the agreement between theoretical and empirical rotation-activity relations at ~650 Myr. The re-purposed Kepler mission, K2, has allowed me to measure rotation periods for dozens of Hyads and hundreds of Praesepe members, including the first periods measured for fully convective Hyads. These data have enabled new tests of models describing the evolution of stellar rotation; discrepancies with these models imply that we still do not fully understand how magnetic fields affect stellar spin-down. I show how we can compare the dependence of H-alpha and X-ray emission on rotation in order to test theories of magnetic field topology and stellar dynamos. These tests inform models of stellar wind-driven angular momentum loss and the age-rotation-activity relation. I also present rotation periods measured for 48 Hyads and 677 Praesepe members with K2, and discuss the impact of unresolved binaries on the study of rotational evolution.