VictorJuiz/thesis huggingface dataset:
Foaming of Wood Flour/Polyolefin/Layered Silicate Composites

This research provides a new insight on various properties, such as rheological, mechanical, and flame-retarding properties, as well as the foaming behaviors of wood flour /plastic composites (WPCs) through the addition of a small amount of nanosized clay particles. Although WPCs have replaced natural wood in many applications, their industrial usage has been limited because of their weak modulus, low impact strength, low screwing-ability/nailing-ability, high density compared to natural wood, as well as their flammability compared to plastics. In this context, the incorporation of nanoclay and foam structure into WPC has been studied to dramatically alleviate these drawbacks. The melt blending method was used to prepare different types of clay-filled wood flour composites such as intercalated and exfoliated clay nanocomposites. The effects of key processing variables such as the mixing time, mixing temperature and screw speed on clay dispersion were investigated from the thermodynamic and kinetic point of view. Their nanostructure was determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Accordingly, effective strategies for controlling intercalation and exfoliation of polyolefin/clay nanocomposites were proposed and evaluated. Wood flour composites with high levels of clay dispersion were synthesized successfully using a general new route (i.e., maleated-polyolefin-based clay masterbatch and dilution). The effects of nanoclay particles on the rheological, thermal, and mechanical properties were identified. In addition, it was demonstrated that a small amount of well-dispersed nanoclay in WPC significantly improved flame retardancy of WPCs. The mechanism of improved flame-retarding effects on nanoparticles was elucidated as well. The relationship between the clay dispersion and the material properties were also clarified. Furthermore, the foaming behaviors of HDPE-based and PP-based wood flour/nanoclay composites were investigated using N2 as the blowing agent in an extrusion process. The cell nucleation and growth behaviors of wood flour/polyolefin/clay composite foams were elucidated while varying the temperature, pressure, wood flour content, clay content and dispersion degrees.

Keywords: wood flour
polyolefin
nanocomposite
foaming
Advisor: Sain, Mohini
Park, Chul B.
Exploiting Task-document Relations in Support of Information Retrieval in the Workplace

Increasingly, workplace information seeking takes place in digital information environments and is reliant upon search systems. Existing systems are designed to retrieve information that is relevant to the query, but are not capable of identifying information that is well-suited to the context and situation of a search. This is a problem for professionals who often are searching for a small amount of useful information that can be applied to a problem or task, and have limited time to browse through large sets of results. This inability of search systems to discriminate between relevant and useful documents is one of the core problems in information retrieval. In this dissertation, I address this problem by studying the role that contextual factors play in determining how a group of professionals searches for and selects information. The central question concerns the nature of the relationships between these contextual factors, specifically between the genres in the document collection and the tasks of the searcher, with an aim to exploit such relationships to improve workplace information retrieval. Research was conducted through multiple studies in three phases, moving from an exploratory study of workplace information behaviour to a controlled experimental user study. Findings confirm that workplace context shapes search behaviour. This relationship is modeled as a set of key contextual factors and sets of context-dependent access constraints, preferred document characteristics, and search strategies. Among the contextual factors identified, work tasks and information tasks were found to be significantly associated with document genres. This task-genre relationship was modeled as a matrix of associations between domain-specific task and genre taxonomies and successfully implemented as a filtering component in a workplace search system. This is the first major study of the relationship between task and genre in information seeking and of its application to information retrieval systems.

Keywords: information retrieval
information seeking
tasks
genre
Advisor: Toms, Elaine
Smith, Brian Cantwell
Canadian Cossacks: Finding Ukraine in Fifty Years of Ukrainian-Canadian Literature in English

Discourses of diaspora and transnationalism have begun to question previous traditional assumptions about the inevitability of ethnic assimilation by drawing attention to various kinds of hybrid identities, but I contend that, in contemporary Canadian literature, we cannot replace an outmoded model of eventual integration with an uncritical vision of ethnic persistence and hybridity. Much thinking about diasporic and ethnic identities suggests that, on the one hand, there are genuine marginalized identities worthy of inquiry and, on the other, there are symbolic ones undeserving of serious study. This dissertation focuses on the supposedly disingenuous or symbolic kinds of ethnic and diasporic identities, providing an analysis of Ukrainian-Canadian ethnic identity retention in a case study of second-, third-, and fourth-generation Canadians of Ukrainian descent who both read and write in English (not Ukrainian). Looking at Ukrainian-Canadian literature from 1954 to 2003, this dissertation argues: (1) ethnic identity affiliation does not necessarily dissipate with time; (2) ethnic identity in a hostland manifests itself as imagined ties to a homeland; and (3) lacking meaningful public and private recognition of ethnic group membership yields anxiety about subjectivity. I first argue that as multicultural policies drew attention to racial marginalization, Ukrainian-Canadian ethnic identity shifted from being an aspect of socio-economic disenfranchisement to becoming a hyphenated identity with links to Ukraine. I then suggest that in order to make that connection to Ukraine viable, writers attempt to locate Ukraine on the Canadian prairie as a substitute home-country. Such attempts give rise to various images Ukrainian-Canadian uneasiness and discomfort, primarily as authors struggle to account for First Nations’ prior presences on the landscape that they want to write as their own. Further, I analyze attempts to locate ethnic authenticity in post-independence Ukraine that also prove unsatisfactory for Ukrainian-Canadian subject formation. The many failed attempts to affix Ukrainian-Canadianness as a meaningful public and private identity give rise to unsettled and ghostly images that signal significant ethnic unease not to be overlooked in analyses of ethnic and diasporic identities. In these ways, this dissertation contributes to ongoing debates and discussions about the place of contemporary literary ethnicity in Canada.

Keywords: ethnic
multicultural
diasporic
identity politics
transnational
nationalism
Advisor: Brown, Russell
Shakespeare's Telling Words: Grammar, Linguistic Encounters, and the Risks of Speech

This dissertation analyzes undertheorized grammatical and linguistic details of Shakespeare’s language. Using tools derived from the fields of linguistics, pragmatics, and discourse analysis, I trace the ways that Shakespeare’s speakers represent themselves in language, and how they position themselves relative to their interlocutors. Grounding my study in a selection of Shakespeare’s works in which questions of self-positioning are particularly fraught, I argue that the nuances of grammar that undergird the linguistic performance of Shakespeare’s speakers encode significant clues about interaction and interpersonal relationships. I maintain that the minute details of linguistic encounters, easily overlooked words such as modal verbs (particularly shall and will) and deictic markers (words such as I, this, and now), hold important information about speakers’ perceptions of themselves, their interlocutors, and their environment. Attention to such details, and to charged moments of linguistic encounter in which speakers must negotiate their modes of self-positioning, helps to illuminate the troubled processes of self-representation and changing self-perception. Chapter one focuses on Shakespeare’s sonnets, and suggests that these poems provide a productive model for the examination of the nuances of speech and interactive dialogue. I anchor my discussion in the particular resonance of the word shall in the sonnets, and explore the ways in which the sonnet speaker attempts to preserve linguistic control relative to a threatening interlocutor. The second chapter extends these concerns to consider how the speakers of Troilus and Cressida respond to a wide network of potentially threatening interlocutors. In this chapter, I focus on linguistic encounters such as arguments and gossip to examine the risks that speakers encounter when they enter the fray of communal discourse. My third chapter turns to Coriolanus to consider moments of aggressive linguistic collisions, in which speakers vie for the right to speak a potent and contested word such as shall. The fourth and final chapter analyzes Richard II through the frame of deictic markers and grammatical modes of self-reference to consider the protective strategies afforded by language in moments of crisis.

Keywords: Shakespeare
English language
literature
grammar
early modern English
modal verbs
early modern drama
Advisor: Magnusson, Lynne
Visions and Revisions: The Sources and Analogues of the Old English Andreas

This dissertation investigates through the paradigms of the opus geminatum genre the relationship of the Old English verse Andreas to its potential exemplars, influences and subsequent renderings. The study focuses specifically upon the ways in which inherited textual dynamics of the opus geminatum—a pair of texts, one in verse and one in prose, which ostensibly treat the same subject—contribute to substantive and stylistic parallels or deviations between Andreas and these other texts. The first chapter positions the paradigm of the opus geminatum alongside the ongoing discussions about the relationships both of internal elements within Andreas, and between Andreas and its Latin or Old English analogues. It provides a detailed overview of the opus geminatum as this grows out of late antique traditions of paraphrase and into the distinctive and highly nuanced genre which Anglo-Saxon authors made their own. It argues that amidst the debates about Andreas’ relationship to other texts, the opus geminatum affords both an historically appropriate and potentially very productive paradigm. The second chapter considers within this paradigm the interplay of content and style between Andreas and what is often thought to be its closest Latin exemplar found in the Casanatensis manuscript, for I contend here that the shift in style, from Latin prose to Old English verse, bears a necessary, dramatic and consistently overlooked influence upon the content of the Old English Andreas, changing not only how one reads that content, but the very substantive nature of the content itself. In Chapter Three the discussion shifts to the relationship Andreas has with an indigenous work, Beowulf, for which a number of recent studies have laid a new groundwork which suggests exciting possibilities for analysis, most significantly at the formulaic level, exploring the tension between explicit oral and literary indebtedness between the two poems. Finally, in Chapter Four the focus shifts to a comparison between the verse Andreas and its Old English prose version of the legend, in MS Cambridge, Corpus Christi College, 198, fols. 386r–394v, allowing one to explore in concrete detail the assertions which opus geminatum writers like Alcuin made about the difference and affinities between prose and verse treatments of opus geminatum texts. My conclusion draws together the broad tendencies mapped throughout this inquiry and considers the intrinsically relational nature of a text like Andreas. It argues in light of uncovered evidence for the efficacy and flexibility of the methods intrinsic to the opus geminatum as a highly appropriate analytical lens and explores from the broad perspective how this paradigm opens numerous horizons of engagement, such as with the embedded language of the liturgy in MS Cambridge, Corpus Christi College, 198, or the self-conscious investment of secular literary traditions in Beowulf with Christian literary projects, such as Andreas.

Keywords: Andreas
Old English
Hagiography
Saints
Advisor: Orchard, Andy
Global and Fine Scale Molecular Studies of Polyploid Evolution in Crataegus L. (Rosaceae)

As many as 70% of angiosperm species are known to contain polyploids, but many aspects of polyploid evolution are unclear in woody plants. Crataegus is a woody genus of Rosaceae comprising 140-200 species that are widely distributed in the Northern Hemisphere. Several species, particularly those in North America, are shown to contain polyploids. The overall goal of the thesis is to provide a better understanding of polyploid evolution by resolving problems from intergeneric to intraspecific levels in Crataegus using phylogenetic and population genetic approaches. Three major aspects were investigated: (1) Phylogeography of the Old and New World Crataegus; (2) Reproductive system and distribution of cytotypes of the black-fruited series Douglasianae in Pacific Northwest and; (3) Origins, population structure, and genetic diversity of diploid and polyploid species. Phylogenetic analyses of molecular data provide evidences of historical events such as trans-Beringian migrations and North Atlantic vicariance that contributed to modern distribution of Crataegus. Poor resolution and short internal branches in eastern North American species suggest genetic bottlenecks and/or rapid divergence following glaciations. In the Pacific Northwest, polyploids of series Douglasianae show a wider distribution and ecological amplitude than diploids. Parsimony tree and network analyses indicate that autotriploids and allotriploids occur in C. suksdorfii, while tetraploid C. suksdorfii are formed via the triploid bridge followed by introgression of sympatric C. douglasii. At the regional level, microsatellite data indicate a separation of the Pacific coastal diploids and triploids from the Columbia Plateau and Rocky Mountain triploids and tetraploids. High genetic differentiation among C. suksdorfii populations suggests that gene flow is limited by ploidy level differences as well as geographical distance. Within-population multilocus genotypic variation is greatest in sexual diploids, and least in apomictic triploids. Frequent gene flow via seed dispersal contributes to an appreciable level of intrapopulation diversity in apomictic tetraploids, and counterbalances the effects of apomixis and/or self-fertilization, which diminish genetic variation within and between seed families. These findings collectively clarify taxonomy and historical biogeography, provide an explicit reticulation model for polyploid formation, and shed light on evolution of natural populations in woody plants that show heterogeneous ploidy levels and reproductive systems.

Keywords: Polyploidy
Molecular evolution
Crataegus
Phylogeny
Population structure
Apomixis
Advisor: Dickinson, Timothy
Stefanovic, Sasa
Survival, Song and Sexual Selection

Darwinian sexual selection predicts that males with the most extravagant secondary sexual traits suffer elevated mortality. Although correlative evidence has generally not borne this idea out, recent research, including a field cricket study, showed that investment in sexually selected traits is costly to survival. I investigated male survival, ornamentation (song) and mating success in a North American grylline, Gryllus pennsylvanicus, to test the generality of previous work and highlight the importance of ecology differences to resource allocation. As the calling songs of older male G. pennsylvanicus are highly attractive to females, in Chapter 2 I tested whether male age correlated with calling song and found a weak but statistically significant correlation, thus leaving open the possibility that choosy females use an age-based indicator mechanism. In Chapter 3, I tested the condition dependence of male survival and calling effort. In contrast to previous work, I found that high condition males both called more and lived longer than low condition males, although there was no trade-off between survival and calling effort. The substantial condition dependence of calling effort suggests that calling effort is under strong directional selection. In Chapter 4 I tested whether female mating preferences resulted in strong selection on male calling effort. I also tested for the condition dependence of female mating preferences. I found that female choosiness was condition-dependent, but the rank of preferred male songs (preference function) was not. Both low and high condition females preferred high calling effort over low calling effort song. In Chapter 5 I tested for evidence of nonlinear selection on male survival that might explain the nonlinear pattern of male investment in survival seen in Chapter 3 (i.e. male survival leveled-off with increasing condition). I found that socially experienced females, but not virgin and naive females, exerted linear selection on male age. I discuss these and the other results of my thesis in the context of previous work on field crickets and condition-dependent ornamentation. Finally, Appendix A reports results that confirm ancient Chinese cultural knowledge that large headed male crickets are more successful in male-male combat.

Keywords: Gryllus pennsylvanicus
Gryllus
Gryllidae
Orthoptera
life history
lifespan
condition dependence
calling effort
bioacoustics
selection analysis
mating preferences
male-male competition
field cricket
cricket fighting
Advisor: Gwynne, Darryl Trevor
Evolutionary History and Biogeography of Papionin Monkeys

Climate change has been invoked to explain patterns of speciation, extinction and biogeographic change over time, however it can be a difficult hypothesis to test empirically. One area of particular interest is climate change in the African Neogene, linked with the origin of hominins. A perfect model clade to test these hypotheses is the papionin monkeys, a diverse group (both extinct and extant), represented by an excellent fossil record. I describe new fossil papionin specimens from Coopers Cave, South Africa, and redescribe and discuss some previously known fossil material. This rich data set provides a necessary deep-time perspective, and, in conjunction with independently generated data, can be used to test hypotheses related to climatic and geological events (such as increasing late Pleistocene aridity and persistence of forest refugia) that may be directly linked to patterns of speciation and biogeographic distribution in the fossil record and in living species. Testing these hypotheses requires a robust phylogenetic hypothesis. I collected morphological character data for a species-level phylogenetic analysis of the papionin clade in order to reconstruct the phylogeny of the group. My analysis found that the living species Theropithecus gelada is nested within extinct theropiths, and is primitive relative to the Pleistocene taxa Theropithecus darti, T. oswaldi and T. leakeyi. Also falling within the theropith lineage are the early Pliocene taxon Pliopapio, the South African taxa Dinopithecus and Gorgopithecus, and two species whose relationships were uncertain until my analysis. “Papio” quadratirostris and “Papio” baringensis are nested within the theropiths, and should be referred to the genus Theropithecus. Biogeographic analysis demonstrates that papionin monkeys share a similar pattern with other Neogene African mammals; they first disperse out of Africa during the mid-Miocene, return to Africa by the late Miocene and undergo a series of vicariant speciation events and range restriction to central Africa, but disperse out into eastern and southern Africa by the Pleistocene. These speciation and dispersal events are tightly correlated with global climatic and tectonic changes.

Keywords: primate
phylogenetic systematics
Pliocene
Pleistocene
Africa
fossil
Advisor: Reisz, Robert R.
Taxonomic, Phylogenetic, and Morphological Diversity of Anomodonts (Tetrapoda, Therapsida)

Anomodonts are a group of non-mammalian synapsids (“mammal-like reptiles”) that represents the dominant herbivores of their time. Their great taxonomic and morphological diversity, unparalleled by any other clade of Permian-Triassic terrestrial tetrapods, is well documented by a cosmopolitan fossil record. In addition, anomodonts survived the most severe extinction event in Earth’s history at the end of the Permian and experienced a second diversification in the Triassic. Thus, they are an ideal clade to investigate macroevolutionary patterns and play an important role in evaluating the impact of the end-Permian extinction on the terrestrial realm. This work combines descriptive, phylogenetic, and quantitative approaches to study evolutionary patterns of anomodonts with special focus on diversity patterns through time. A taxonomic revision of the Late Permian dicynodont genus Emydops reflects the necessity for a solid taxonomic basis for diversity studies. The description of a new species of this genus is combined with a discussion of dental variability and pathology in dicynodont anomodonts. A detailed description of the postcranial anatomy of the basal anomodont Suminia reveals new insights into the early evolution of anomodonts and therapsids in general. Several derived features, in particular in the autopodium, are unique to Suminia and together with a comparative morphometric analysis indicate grasping abilities of this taxon and the earliest evidence for arboreality in the vertebrate fossil record. The cranial anatomy of the Triassic dicynodont Kombuisia is restudied and a phylogenetic evaluation of the survivorship of anomodonts across the Permian-Triassic boundary reveals more surviving lineages than previously recognized. A review of anomodont-bearing tetrapod faunas forms the basis for a faunal similarity analysis that reveals stratigraphic as well as geographic patterns in faunal groupings. The taxonomic diversity of anomodonts reflects three diversifications and subsequent extinctions in the early Middle Permian, the Early Triassic and the mid-late Triassic.

Keywords: paleontology
extinction
diversity
richness
Advisor: Reisz, Robert R.