<p>Recent research in microbial ecology has focused on how aquatic bacterial communities are assembled. Only a few of these studies follow a “Gleasonian” approach where the roles of single bacterial populations are in focus. In this thesis, novel molecular tools were used to describe the distribution and evolutionary relationships of microbes in productive aquatic environments. Many new phylogenetic groups of bacteria were identified, likely representing bacterial populations restricted to productive freshwaters. I also addressed the dynamics and functional role of individual bacterial populations in eutrophic lakes and brackish environments with a focus on either biogeochemically significant or potentially pathogenic representatives. <i>Flavobacteria</i> blooms were observed, on occasions characterized by high heterotrophic production. In addition to high temporal dynamics microbial community composition and function differed on the spatial scale, as exemplified by free-living and <i>Cyanobacteria</i>-associated habitats. At the community scale, microbial processes, such as biomass production and substrate uptake could be predicted from the presence and absence of individual bacterial populations. I also studied the niches of potentially pathogenic <i>Vibrio </i>populations in various coastal waters. Using a novel culture-independent method, a <i>V. cholerae</i> population was detected along the entire Swedish coastline. Results from an environmental survey and a laboratory mesocosm experiment reveal that phytoplankton-derived dissolved organic matter enhance the growth of <i>V. cholerae</i> and other <i>Vibrio</i> spp. and hence create a largely overlooked niche for these heterotrophic bacteria. This thesis and future work on the role of individual bacterial populations will facilitate predictions of biogeochemical cycles and the distribution of bacteria in the context of global climate change and local eutrophication.</p>

Hash tables (HTs) are used to implement various lookup schemes and they need to be efficient in terms of speed, space utilization, and power consumptions. For IP lookup, the hashing schemes are attractive due to their deterministic O(1) lookup performance and low power consumptions, in contrast to the TCAM and Trie based approaches. As the size of IP lookup table grows exponentially, scalable lookup performance is highly desirable. For next generation high-speed routers, this is a vital requirement when IP lookup remains in the critical data path and demands a predictable throughput. However, recently proposed hash schemes, like a Bloomier filter HT and a Fast HT (FHT) suffer from a number of flaws, including setup failures, update overheads, duplicate keys, and pointer overheads. In this dissertation, four novel hashing schemes and their architectures are proposed to address the above concerns by using pipelined Bloom filters and a Fingerprint filter which are designed for a memory-efficient approximate match. For IP lookups, two new hash schemes such as a Hierarchically Indexed Hash Table (HIHT) and Fingerprint-based Hash Table (FPHT) are introduced to achieve a a perfect match is assured without pointer overhead. Further, two hash mechanisms are also proposed to provide memory and power efficient lookup for packet processing applications. Among four proposed schemes, the HIHT and the FPHT schemes are evaluated for their performance and compared with TCAM and Trie based IP lookup schemes. Various sizes of IP lookup tables are considered to demonstrate scalability in terms of speed, memory use, and power consumptions. While an FPHT uses less memory than an HIHT, an FPHT-based IP lookup scheme reduces power consumption by a factor of 51 and requires 1.8 times memory compared to TCAM-based and trie-based IP lookup schemes, respectively. In dissertation, a multi-tiered packet classifier has been proposed that saves at most 3.2 times power compared to the existing parallel packet classifier. Intrinsic hashing schemes lack of high throughput, unlike partitioned Ternary Content Addressable Memory (TCAM)-based scheme that are capable of parallel lookups despite large power consumption. A hybrid CAM (HCAM) architecture has been introduced. Simulation results indicate HCAM to achieve the same throughput as contemporary schemes while it uses 2.8 times less memory and 3.6 times less power compared to the contemporary schemes.

Computers were not built with security in mind. As such, security has and still often takes a back seat to performance. However, in an era where there is so much sensitive data being stored, with cloud storage and huge customer databases, much has to be done to keep this data safe from intruders. Control flow hijacking attacks, stemming from a basic code injection attack to return-into-libc and other code re-use attacks, are among the most dangerous attacks. Currently available solutions, like Data execution prevention that can prevent a user from executing writable pages to prevent code injection attacks, do not have an efficient solution for protecting against code re-use attacks, which can execute valid code in a malicious order. To protect against control flow hijacking attacks, this work proposes architecture to make Control Flow Integrity, a solution that proposes to validate control flow against pre-computed control flow graph, practical. Current implementations of Control Flow Integrity have problems with code modularity, performance, or scalability, so I propose Dynamic Bloom Cache, a blocked-Bloom-filter-based approach, to solve current implementation issues.

Over the past two decades, Lake Winnipeg has been experiencing increasingly rapid eutrophication, and large cyanobacterial blooms now form in the North Basin in most years in late summer or fall. Cyanobacteria are considered a relatively poor food source compared with other phytoplankton, but the impacts of these blooms upon the primary consumers in the lake have not previously been researched. A microscopic analysis of whole water samples found cyanobacteria to be scarcely present in summer 2012, with nitrogen-fixing and non-fixing cyanobacteria comprising 11.2% and 8.4% of the basin-wide biovolume, respectively, and all but absent in fall. Gut content analysis of chironomids found that cyanobacteria made up an almost negligible part of their diet. Stable isotope analysis revealed that nitrogen-fixing cyanobacteria reduced phytoplankton δ15N values, and that this same reduction could be traced through the zooplankton, but not down to the sediments or chironomids.

The present thesis focuses on the critical dialogues on the literary canon developed between 1970 and 2000 in the United States as a crucial juncture for the consolidation of the notion of canon as a scholarly subject matter within the field of literary studies. By taking stock of the abundance of scholarly contributions on the literary canon produced at this time, this thesis pursues two aims: first, it initiates a process of systematisation of the scholarly material on the canon produced during the last thirty years of the twentieth century; second, it focuses on a selection of particularly influential works that have furthered the understanding of specific aspects of the notion of canon. Two introductory chapters outline respectively the historical and the theoretical background of this research. Chapter One explores the historical framework within which the canon started to receive increasing critical attention inside and outside U.S. academia. In particular, it observes how the historical and cultural phenomenon known as the Culture Wars came to bear upon the way in which the notion of canon was perceived and treated by critics and scholars. Early and later examples of canonical criticism are juxtaposed so as to argue that the absorption of debates about the definition of national cultural heritage within U.S. academia influenced the terms in which the canon was being discussed, privileging oppositional rhetorical strategies over the more moderate tones of early theoretical approaches. Chapter Two draws on Jan Gorak’s work in The Making of The Modern Canon: Genesis and Crisis of a Literary Idea (1991) to explore the history of the concept of canon and of its associations with the diverging attitudes adopted by critics in relation to the canon in the period in exam. The second part of this thesis constitutes of three case studies that illustrate the significance for our understanding of the concepts of canon, canonicity and canon formation, of three texts published in the 1990s by Harold Bloom, John Guillory and Henry Louis Gates, Jr. Each chapter observes how these studies contributed to clarify the relationship between the idea of canon and that of tradition, between canon and ideology and, finally, between the canon and the anthology, respectively. Chapter Three locates Bloom’s The Western Canon: The Books and Schools of Ages (1994) in relation to his earlier theory of the anxiety of influence and argues that Bloom’s account of canon formation relies on his definition of tradition as the agonistic struggle between poets and their predecessors. Chapter Four is a close reading of John Guillory’s Cultural Capital: The Problem of Literary Canon Formation (1993) and explores the political ideology underlying its selective use of the work of Pierre Bourdieu, Antonio Gramsci and T.S.Eliot. Finally, Chapter Five engages with Henry Louis Gates, Jr.’s attempt to establish a canon of African American Literature through his role as editor of the Norton Anthology of African American Literature (1996).

Over the past two decades, Lake Winnipeg has been experiencing increasingly rapid eutrophication, and large cyanobacterial blooms now form in the North Basin in most years in late summer or fall. Cyanobacteria are considered a relatively poor food source compared with other phytoplankton, but the impacts of these blooms upon the primary consumers in the lake have not previously been researched. A microscopic analysis of whole water samples found cyanobacteria to be scarcely present in summer 2012, with nitrogen-fixing and non-fixing cyanobacteria comprising 11.2% and 8.4% of the basin-wide biovolume, respectively, and all but absent in fall. Gut content analysis of chironomids found that cyanobacteria made up an almost negligible part of their diet. Stable isotope analysis revealed that nitrogen-fixing cyanobacteria reduced phytoplankton δ15N values, and that this same reduction could be traced through the zooplankton, but not down to the sediments or chironomids.

Thesis (Ph. D.)--Cornell University, 1989. / Vita. Includes bibliographical references.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 239-242).

Algal bloom can significantly impact reverse osmosis desalination process and reduce the drinking water production. In 2008, a major bloom event forced several UAE reverse osmosis plants to stop their production, and in this context, a better understanding of UF membrane fouling caused by algal organic matter (AOM) is needed, in order to adjust the filtration conditions during algal bloom events. Polymeric MF/UF membranes are already widely used for RO pretreatment, but ceramic UF membranes can also be an alternative for the filtration of marine algal solutions. The fouling potential of the Red Sea and the Arabian Sea, sampled at different seasons, along with four algal monocultures grown in laboratory, and one mesocosm experiment in the Red Sea was investigated. Algal solutions induce a stronger and more irreversible fouling than terrestrial humic solution, toward ceramic membrane. During algal bloom events, this fouling is enhanced and becomes even more problematic at the decline phase of the bloom, for a similar initial DOC. Three main mechanisms are involved: the formation of a cake layer at the membrane surface; the penetration of the algal organic matter (AOM) in the pore network of the membrane; the strong adhesion of AOM with the membrane surface. The last mechanism is species-specific and metal-oxide specific. In order to understand the stronger ceramic UF fouling at the decline phase, AOM quality was analyzed every two days. During growth, AOM is getting enriched in High Molecular Weight (HMW) structures (> 200 kDa), which are mainly composed by proteins and polysaccharides, and these compounds seem to be responsible for the stronger fouling at decline phase. In order to prevent the fouling of ceramic membrane, coagulation-flocculation (CF) using ferric chloride was implemented prior to filtration. It permits a high removal of HMW compounds and greatly reduces the fouling potential of the algal solution. During brief algal bloom events, CF should be implemented prior to UF to protect the membranes. A comparison between polymeric and ceramic UF membranes showed that ceramic membrane suffers from a stronger fouling but permits a better removal of DOC and particularly HMW compounds.

Submitted by Roberth Novaes (roberth.novaes@live.com) on 2018-07-16T13:14:30Z No. of bitstreams: 1 MESTRADO_Dissertacao_Plutarco_Ryszard.pdf: 1444483 bytes, checksum: 407185b2d5e4e4ac4a62da590ca53462 (MD5) / Approved for entry into archive by Setor de Periódicos (per_macedocosta@ufba.br) on 2018-07-16T20:01:36Z (GMT) No. of bitstreams: 1 MESTRADO_Dissertacao_Plutarco_Ryszard.pdf: 1444483 bytes, checksum: 407185b2d5e4e4ac4a62da590ca53462 (MD5) / Made available in DSpace on 2018-07-16T20:01:36Z (GMT). No. of bitstreams: 1 MESTRADO_Dissertacao_Plutarco_Ryszard.pdf: 1444483 bytes, checksum: 407185b2d5e4e4ac4a62da590ca53462 (MD5) / Plutarco de Queroneia (46-120) foi um prolífico polímata grego do período do Império Romano. Plutarco se destacou nos campos da Literatura, História, biografia, retórica e da filosofia. A obra de Plutarco teve o objetivo de preservar a cultura e a identidade gregas e promover esta cultura grega perante Roma, acentuando a helenização do povo romano. Este presente texto constitui uma experiência de crítica literária baseada, sobretudo, no método de Otto Maria Carpeaux associado com a crítica de Harold Bloom. Neste texto são estudados os elementos literários das duas principais biografias de Plutarco: Vida de Alexandre e Vida de Júlio César, além da atividade comparativa entre Plutarco, Homero e Platão. / Plutarch of Queroneia was a prolific Greek polymath of the Roman Empire. The work of Plutarch excelled in the fields of Literature, History, biography, rhetoric and philosophy. The Plutarch‟s work aimed to preserve the Greek culture and Greek identity and promote this Greek culture in Rome, accentuating the Hellenization of the Roman elite. This present text is an experience of literary criticism based primarily on Otto Maria Carpeaux Method associated with the criticism of Harold Bloom. Here, have studied the literary elements of the two major biographies of Plutarch: Life of Alexander and Life of Julius Caesar, in addition to comparative activity among Plutarch, Homer and Plato.