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This thesis is focused on two topics: (i) synthesis and characterization of bilayer graphene and pyrolytic carbon by atmospheric pressure chemical vapor deposition, and (ii) application of graphene in the fabrication of a buckyball memory device. Monolayer and bilayer graphene are semi-metal with zero bandgap. One can induce a bandgap in bilayer graphene by applying a gate voltage in the stacking direction. Thus, bandgap and Fermi level in bilayer graphene can be controlled simultaneously with a double-gate device, making it a useful material for future semiconducting applications. Controlled synthesis of bilayer graphene would be the first step to fabricate bilayer graphene based devices. In this context, we report a uniform and low-defect synthesis of bilayer graphene on evaporated nickel films. Ultra-fast cooling is employed to control the number of layers and sample uniformity. The process is self-limiting, which leads to bilayer graphene synthesis over a wide range of growth-time and precursor flow-rate. Pryolytic carbon is another important carbon nanomaterial, due to its diverse applications in electronic and biomedicalengineering. We employ chemical vapor deposition with ultra-fast cooling technique to synthesize pyrolytic carbon. Furthermore, we elucidate a method to calculate the in-plane crystal size by using Raman spectroscopy. Finally, the use of bilayer graphene in a write-once read-many memory device has been demonstrated. The device showed irreversible switching from low-resistance to high-resistance state, with hysteresis in the transport characteristics. The control sample showed random switching and hysteresis due to electromigration of metal atoms into the active material of the device. We attribute the reliability and performance of the reported device to the ultra-smooth graphene contacts, which additionally inhibits electromigration from the underlying metallic film. Moreover, the memory device showed excellent endurance and retention characteristics.

The incorporation of porosity in a material potentially results in the changes in electrical, mechanical and electrical properties and has generated much interest by researchers. The development of new techniques for inducing porosity in thin films may prove advantageous if they lead to a decrease in processing complexity, or an increase in the processing flexibility by widening the window of compatible physical conditions, or the improvement of the final properties of the porous materials. Two processing techniques were developed to produce porosity in thin dielectric films at temperatures below the glass transition temperature of the host matrix. These glassy-regime processing methods relied on the susceptibility of hydrogen silsesquioxane (HSQ) to gelation in the glassy regime when exposed to polar substances. Both of these glassy-regime processing methods relied on the susceptibility of hydrogen silsesquioxane (HSQ) towards gelation in the glassy regime when exposed to polar substances. The first processing method made use of co-solvent mixtures of polar non-protic organic solvent to serve both as gelation catalysts and pore-generators. HSQ films were soaked in the polar organic co-solvents, which penetrated the films and initiated crosslinking throughout the matrix. Afterwards the films were baked, volatilizing entrapped solvents and producing air pockets within the rigid matrix. The second porosity method used UV-radiation to initiate acid-catalyzed decomposition of polycarbonate sacrificial polymers after first using bases to catalyze the gelation of HSQ. The radiation-based (direct-write) decomposition of the porogen enabled the selective patterning of regions porosity via the use of a photomask, which resulted in the creation of refractive index profiles in the direct-written films. Porous films that were produced by these two glassy-state processing techniques were used to build slab waveguide structures. Optical characterization experiments showed that the fabricated waveguides had average propagation losses of 16 - 27 dB/cm for the first guided TE mode and about 36-40 dB/cm, for the second TE guided mode. It is believed that the large propagation loss values were caused by a combination of the Rayleigh scattering from the relatively large UV-induced pores produced in the direct-write layers as well as scattering induced by surface roughness.

Flash memories have become the main type of non-volatile memories. They are widely used in mobile, embedded and mass-storage devices. Flash memories store data in floating-gate cells, where the amount of charge stored in cells – called cell levels – is used to represent data. To reduce the level of any cell, a whole cell block (about 106 cells) must be erased together and then reprogrammed. This operation, called block erasure, is very costly and brings significant challenges to cell programming and rewriting of data. To address these challenges, rank modulation and rewriting codes have been proposed for reliably storing and modifying data. However, for these new schemes, many problems still remain open. In this work, we study error-correcting rank-modulation codes and rewriting codes for flash memories. For the rank modulation scheme, we study a family of one- error-correcting codes, and present efficient encoding and decoding algorithms. For rewriting, we study a family of linear write-once memory (WOM) codes, and present an effective algorithm for rewriting using the codes. We analyze the performance of our solutions for both schemes.

This thesis aims to present solutions to improve the performance of SQLite library on mobile systems. In particular, two approaches are presented to add lightweight locking mechanisms to the SQLite library and improve concurrency of the SQLite library on Android operating system. The impact on performance is discussed after each section. Many applications on the Android operating system rely on the SQLite library to store ordered data. However, due to heavy synchronization primitives used by the library, it becomes a performance bottleneck for applications which push large amount of data into the database. Related work in this area also points to SQLite database as one of the factors for limiting performance. With increasing network speeds, the storage system can become a performance bottleneck, as applications download larger amounts of data. The following work in this thesis addresses these issues by providing approaches to increase concurrency and add light-weight locking mechanisms. The factors determining the performance of Application Programming Interfaces provided by SQLite are first gathered from IO traces of common database operations. By analyzing these traces, opportunities for improvements are noticed. An alternative locking mechanism is added to the database file using byte-range locks for fine-grained locking. Its impact on performance is measured using SQLite benchmarks as well as real applications. A multi-threaded benchmark is designed to measure the performance of fine grained locking in multi-threaded applications using common database operations. Recent versions of SQLite use write ahead logs for journaling. We see that writes to this sequential log can occur concurrently, especially in flash drives. By adding a sequencing mechanism for the write ahead log, the writes can proceed simultaneously. The performance of this method is also analyzed using the synthetic benchmarks and multi-threaded benchmarks. By using these mechanisms, the library is observed to gain significant performance for concurrent writes.

Computing in the last decade has been characterized by the rise of data- intensive scalable computing (DISC) systems. In particular, recent years have wit- nessed a rapid growth in the popularity of fast analytics systems. These systems exemplify a trend where queries that previously involved batch-processing (e.g., run- ning a MapReduce job) on a massive amount of data, are increasingly expected to be answered in near real-time with low latency. This dissertation addresses the problem that existing designs for various components used in the software stack for DISC sys- tems do not meet the requirements demanded by fast analytics applications. In this work, we focus specifically on two components: 1. Key-value storage: Recent work has focused primarily on supporting reads with high throughput and low latency. However, fast analytics applications require that new data entering the system (e.g., new web-pages crawled, currently trend- ing topics) be quickly made available to queries and analysis codes. This means that along with supporting reads efficiently, these systems must also support writes with high throughput, which current systems fail to do. In the first part of this work, we solve this problem by proposing a new key-value storage system – called the WriteBuffer (WB) Tree – that provides up to 30× higher write per- formance and similar read performance compared to current high-performance systems. 2. GroupBy-Aggregate: Fast analytics systems require support for fast, incre- mental aggregation of data for with low-latency access to results. Existing techniques are memory-inefficient and do not support incremental aggregation efficiently when aggregate data overflows to disk. In the second part of this dis- sertation, we propose a new data structure called the Compressed Buffer Tree (CBT) to implement memory-efficient in-memory aggregation. We also show how the WB Tree can be modified to support efficient disk-based aggregation.

Este trabalho dissertativo tem por principal objetivo identificar e rastrear as percepções que o escritor argentino, Jorge Luís Borges, possuía sobre a história (mesmo não sendo historiador de formação) e como essas se manifestam através de seus contos literários. Para tanto, são analisados uma série de contos de sua autoria que priorizem essa investigação, produzidos em diversos e distintos momentos de sua vida. O texto dividese em duas partes (atos): no primeiro nosso enfoque será como Borges percebe o ato de se fazer/escrever história, ou seja, como se dá a produção, publicação, manifestação e aceitação de um texto histórico, e para isso cotejaremos três contos, La loteria en Babilonia, Tema del traidor y del heroe e Guayaquil. No segundo capítulo (ato) traremos uma vertente da escrita de Borges mais ligada a temáticas argentinas, suas narrativas criollas, e como que através dessas o autor constantemente reflete sobre a história da Argentina e de alguns de seus mais tradicionais personagens, os gauchos e compadritos, representando os valores, costumes e tradições dessas emblemáticas figuras. Nesse segundo momento analisaremos os contos Hombre de la esquina rosada, Historia de Rosendo Juárez, El muerto, El fin e El sur. Em ambos os capítulos analisaremos como as percepções e representações de Borges sobre a história, seja em seu caráter mais “filosófico”, seja em seu caráter mais criollista (temáticas ligadas à Argentina) mudam com o passar da vida do autor. Se em um dado momento a história lhe parece “salvadora”, capaz de “gerar mudanças”, em outro lhe parecerá banal e tratada com ironia; já no segundo ato perceberemos como sua percepção sobre coragem como valor representativo de uma argentinidade também irá cambiar, assim como, quando pretende representar a Argentina ou Buenos Aires, seus pensamentos comumente estão ligados muito mais ao passado do que ao presente, gerando um sentimento de nostalgia por parte do autor. O principal objetivo é verificar, como a história, em último caso, será aqui vista como uma das temáticas ou “símbolos” que mais povoou a carreira literária de Jorge Luís Borges. / This research work is primarily focused on identifying and tracking the perceptions that the Argentine writer, Jorge Luis Borges, had on the History (even though he had no historian formation) and how these perceptions are manifested through his literary short stories. Therefore, we selected and analyzed a number of short stories of his own that conduct this research. Those were produced in various and different moments of his life. The dissertation is divided in two parts (acts): on the first one our focus will be on how Borges realizes the act of making / writing history, in other words, we will explore how the production, publication, demonstration and acceptance of a historical text happens, and, for that, we will analyze three short stories, La loteria en Babilonia, Tema del traitor y del héroe and Guayaquil. On the second chapter (act) we will bring Borges’ writings more linked to Argentine themes, their criollas narratives, and how through these narratives the author constantly reflects about the history of Argentina and some of its traditional characters, both the gauchos and compadritos representing their values, customs and traditions of these emblematic figures. On this second moment we will analyze the Hombre de la esquina Rosada, Historia de Rosendo Juárez, El muerto, El fin and El sur. In both chapters we will analyze the perceptions and representations of Borges on the matters of history - on his most "philosophical" texts, or in his most criollista texts (those related to Argentina) – and its changes over the author's life. If at a certain moment the history seems to him as a "savior", something able to "create changes", in another moments it will seem banal and treated with irony; on the second act we realize how his perception of courage as a representative value of an Argentinity will also change, as well as when he wants to represent Argentina or Buenos Aires, his thoughts are usually linked more to the past than to the present, creating a sense of nostalgia felling in the author. Thus, our main objective is to verify how History, ultimately, is seen as a thematic or "symbols" that most appears in the literary work of Jorge Luis Borges.

Made available in DSpace on 2016-08-03T16:16:17Z (GMT). No. of bitstreams: 1 Priscila Vita.pdf: 661978 bytes, checksum: 755f44724595d17f830e0024b5ff3789 (MD5) Previous issue date: 2010-03-22 / Fundação de Amparo a Pesquisa do Estado de São Paulo / The objective of this project is analyse the Read and Write Program of state schools from São Paulo to argue their theorist system elements. The project Read and Write represents one more try from public teaching system on the way to revert the unstable situation presented by students from public schools on the read and write process. The second chapter presents the legislation that endorses the program and also the way how has been applied. The third chapter presents the methodological procedure. Questionnaires had been developed for teachers and elaborated points of analysis to classify depositions from the reports by dialectics categories of theorist system referential made by Alves (2000). Some interviewed teachers believe that the program brings new ideas, however the theoretical referential is based on constructivism that guides the Brazilian education institutional documents for more than 25 years.(AU) / O presente trabalho tem o objetivo de analisar o Programa Ler e Escrever das escolas estaduais de São Paulo, apontando seus possíveis benefícios e principais problemas. O programa representa mais uma tentativa do sistema público de ensino no sentido de reverter o quadro de precariedade apresentado pelos alunos da escola pública no que se refere ao processo de alfabetização. No primeiro capítulo encontram-se considerações pertinentes a alfabetização e concepções de ensino. No segundo capítulo é apresentada a legislação que respalda o programa e também a forma como vem sendo aplicado. O terceiro capítulo trata dos procedimentos metodológicos. Foram desenvolvidos questionários para professores alfabetizadores e professores-coordenadores e elaborados quadros de análise para classificar os depoimentos coletados a partir dos pares de categorias dialéticas do referencial teórico-metodológico construído por Alves (2000). Alguns dos professores entrevistados acreditam que o programa traz idéias novas, porém seu referencial teórico é fundado no construtivismo, que já orienta os documentos institucionais da educação brasileira há mais de 25 anos.(AU)

The diploma thesis is focused on debt management system. Some facts concerning the classification of debts, right pricing and inventory taking have been clarified in the theoretical part. A provision of debts, adjusting item issues and a write-off of debts have been taken into consideration as well. The practical part of thesis focuses on debt analysis, ways of debt provision used in the given company. One chapter deals with outstanding debts. Finally, debt management system in the company is assessed as well as the suggestion of improvement.

Submitted by Leonardo Cavalcante (leo.ocavalcante@gmail.com) on 2018-05-15T12:34:45Z No. of bitstreams: 1 Arquivototal.pdf: 949084 bytes, checksum: a58b7ceb64ccf3fb97ecdb0ce27966c8 (MD5) / Made available in DSpace on 2018-05-15T12:34:45Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 949084 bytes, checksum: a58b7ceb64ccf3fb97ecdb0ce27966c8 (MD5) Previous issue date: 2016-02-29 / This research aimed to investigate how the students of the Zé Peão School Program (PEZP) make use of the reading and the writing, through literacy perspective in their social relations. As regards the theoretical foundations of literacy for realizing this work, we search for support in the historical-cultural approach. It is a qualitative research, with a case study. Data were collected from the non-participant observation technique, in classrooms located at construction sites, in the space of initial and continuing training of PEZP, and observations were recorded in a field diary. Data were also collected by conducting semi-structured interviews with the workers learners. The results revealed that the students surveyed exercise literate social practices and recognize the reading and writing value to their activities and solving everyday problems. Our findings indicate the importance of working pedagogical practices in the process of teaching youths and adults how to read and write, through the perspective of social use of reading and writing. / Esta pesquisa teve como objetivo investigar como os educandos do Programa Escola Zé Peão (PEZP) fazem uso da leitura e da escrita, na perspectiva do letramento em suas relações sociais. No que refere aos fundamentos teóricos do letramento para a relização deste trabalho, buscou-se suporte na abordagem histórico-cultural. Trata-se de uma pesquisa qualitativa, do tipo estudo de caso. Os dados foram coletados a partir da técnica de observação não participante, nas salas de aula localizadas nos canteiros de obras, no espaço da formação inicial e continuada do PEZP, tendo as observações sido registradas em diário de campo. Os dados foram coletados por meio da realização de entrevistas semiestruturadas com os educandos-operários. Os resultados revelaram que os educandos pesquisados exercem práticas socias letradas e reconhecem o valor da leitura e da escrita para as suas atividades e a resolução de problemas cotidianos. As conclusões indicam a importância de serem trabalhadas as práticas pedagógicas, no processo de alfabetização de jovens e adultos, na perspectiva do uso social da leitura e da escrita.