Upper-crustal seismic velocity heterogeneity as derived from a variety of P-wave sonic logs

Sonic-log measurements provide detailed 1-D information on the distribution of elastic properties within the upper crystalline crust at scales from about one metre to several kilometres. 10 P-wave sonic logs from six upper-crustal drill sites in Europe and North America have been analysed for their second-order statistics. The penetrated lithological sequences comprise Archean volcanic sequences, Proterozoic mafic layered intrusions, and Precambrian to Phanerozoic gneisses and granites. Despite this variability in geological setting, tectonic history, and petrological composition, there are notable similarities between the various data sets: after removing a large-scale, deterministic component from the observed velocity-depth function, the residual velocity fluctuations of all data sets can be described by autocovariance functions corresponding to band-limited self-affine stochastic processes with quasi-Gaussian probability density functions. Depending on the maximum spatial wavelength present in the stochastic part of the data, the deterministic trend can be approximated either by a low-order polynomial best fit or by a moving-average of the original sonic-log data. The choice of the trend has a significant impact on the correlation length and on the standard deviation of the residual stochastic component, but does not affect the Hurst number. For trends defined by low-order polynomial best fits, correlation lengths were found to range from 60 to 160 m, whereas for trends defined by a moving average the correlation lengths are dominated by the upper cut-off wavenumber of the corresponding filter. Regardless of the trend removed, the autocovariance functions of all data sets are characterised by low Hurst numbers of around 0.1-0.2, or equivalently by power spectra decaying as ∽ 1/k. A possible explanation of this statistical uniformity is that sonic-log fluctuations are more sensitive to the physical state, in particular to the distribution of cracks, than to the petrological composition of the probed rock

Seismic scattering in the upper crystalline crust based on evidence from sonic logs

Evidence from sonic logs indicates that velocity fluctuations in the upper crystalline crust are remarkably uniform. This motivates a generic approach to classifying upper-crustal seismic heterogeneity and to studying implications for seismic wave propagation. The resulting canonical model of upper-crustal seismic structure is characterized by a spatially isotropic von Kármán autocovariance function with a 100 m, ν ≈ 0.15, and σ ≈ 300 m s−1. Small-angle scattering theory is used to predict the transition from weak to strong scattering as well as phase fluctuations and scattering attenuation. Compared with ‘exponential' random media (ν = 0.50), the high fractal dimension (i.e. small values of ν) of upper-crustal heterogeneity causes smaller phase fluctuations, and transition from weak to strong scattering at lower frequencies and shorter path lengths. Acoustic finite-difference modelling shows that seismic reflections from deterministic features surrounded by heterogeneities are severely degraded when they fall into the strong scattering regime. Conversely, traveltime fluctuations of transmitted waves are found to be relatively insensitive to the transition from weak to strong scattering. Upper-crustal scattering Q is predicted to lie between 600 and 1500, which is one to two orders of magnitude higher than Q-values inferred from seismic data. This suggests that seismic attenuation in the upper crystalline crust is dominated by anelastic effects rather than by scatterin

AMERICAN CULTURE OF SERVITUDE: THE PROBLEM OF DOMESTIC SERVICE IN ANTEBELLUM LITERATURE AND CULTURE

My dissertation argues that domestic service alters a culture’s relationship to the laboring body. I theorize this relationship via popular literary and cultural antebellum texts to explore the effects of servitude as a trope. Methodologically, each chapter reads a literary text in context with social and legal paradigms to 1) demonstrate that servitude undergirds myriad articulations of antebellum power and difference; 2) show how servitude inflects the construction of these paradigms; and 3) trace Americans’ changing relationship to the concept of servitude from the Early Republic through the Civil War. I begin with James Fenimore Cooper’s The Pioneers (1823), exploring the famous Leather-stocking character – not (as has canonically been the case) as an icon of American independence, but as an icon of American servitude. I historicize this reading with the legal history of master/servant statutes in the early nineteenth century. While public opinion quarantined servitude to an oppressed racial minority, the apparatuses of the law were dramatically expanding servitude’s purview, rendering the master/servant relation the touchstone from which to understand all employment relations. Following, my second chapter examines Caroline Kirkland’s A New Home, Who’ll Follow? (1833). I show that Kirkland’s text dramatizes the narrativity of identity-formation and its potential class consequences. Throughout, Kirkland suggests that this is particularly a women’s problem, whose narratives of self are charged with maintaining the narratives of the family and, synecdochically, the nation. Maria Susanna Cummins’s The Lamplighter (1854) is a revolutionary intervention into the narratives of laborless-ness. I read the adoptions within the novel alongside the legalization of bounded servitude for children, since antebellum minors could be adopted or sign indentures if doing so was determined to be in their “best interest.” In my fourth and final chapter, I examine Civil War draft resistance. In her House and Home Papers columns for The Atlantic (1863-4), Harriet Beecher Stowe turned to the tropes of servitude to make sense of these violent eruptions. Yet this strategy laid bare servitude’s place as the basis for many other forms of state power (including military service) and servitude’s incompatibility with principles of individual sovereignty

Challenging Dominant Ideologies in Order to Center Marginalized Voices and Enrich Learning: Theorizing Social Justice in English Studies Teaching

This portfolio explores the reproduction of and challenges to dominant ideologies in popular culture and scholarly contexts and examines pedagogies for advancing social justice in the field of English studies through three distinct but interconnected projects. The first project considers pedagogy in the public sphere, examining the power of the meme genre to serve as “critical public pedagogy” within movements for social change. The second project focuses on the role of dominant norms in reproducing social injustices through classroom writing assessment, offering insights from antiracist, queer, feminist, decolonial, translingual, and disability justice scholars. The paper also reviews composition scholars’ strategies for transforming classroom grading practices and proposes a social justice- and trauma-informed approach to promoting equity and supporting student learning. The third project presents a unit plan and annotated bibliography of scholarly and pedagogical resources for teaching Moshin Hamid’s The Reluctant Fundamentalist in a community college introductory literature course. The unit plan treats the genre of the counter-narrative as a heuristic for teaching critical thinking and literary analysis and for centering marginalized voices. Together, these projects illuminate opportunities for exploring and learning from diverse epistemologies and rhetorical and linguistic modes in the field of English studies and for re-imagining classroom grading practices to create meaningful learning experiences and promote social justice in the teaching of composition, rhetoric, and literature

Strategic Sourcing Via Category Management: Helping Air Force Installation Contracting Agency Eat One Piece of the Elephant

The United States Air Force can dramatically reduce resource consumption through strategic sourcing initiatives that leverage sensibly-bound pockets of spend via category management. However, category creation is a particularly daunting task due to the sheer magnitude of purchasing data in large organizations. Text mining is one way to identify categories. Specifically, term frequency analysis, term frequency-inverse document frequency analysis, and topic modeling can identify category membership, unique characteristics of categories, and thematic natures of the categories. This thesis developed an empirical, generalizable, reproducible methodology to analyze historical contract text descriptions to uncover the data’s hidden structure. A sample case was transformed into a practical hierarchy, which was internally and externally validated. As a foundational methodology, the impact of token selection, domain expertise, and unique contracting language were identified as considerations for future research

Structures of an apo and a binary complex of an evolved archeal b family DNA polymerase capable of synthesising highly cy-dye labelled DNA

Thermophilic DNA polymerases of the polB family are of great importance in biotechnological applications including high-fidelity PCR. Of particular interest is the relative promiscuity of engineered versions of the exo- form of polymerases from the Thermo- and Pyrococcales families towards non-canonical substrates, which enables key advances in Next-generation sequencing. Despite this there is a paucity of structural information to guide further engineering of this group of polymerases. Here we report two structures, of the apo form and of a binary complex of a previously described variant (E10) of Pyrococcus furiosus (Pfu) polymerase with an ability to fully replace dCTP with Cyanine dye-labeled dCTP (Cy3-dCTP or Cy5-dCTP) in PCR and synthesise highly fluorescent “CyDNA” densely decorated with cyanine dye heterocycles. The apo form of Pfu-E10 closely matches reported apo form structures of wild-type Pfu. In contrast, the binary complex (in the replicative state with a duplex DNA oligonucleotide) reveals a closing movement of the thumb domain, increasing the contact surface with the nascent DNA duplex strand. Modelling based on the binary complex suggests how bulky fluorophores may be accommodated during processive synthesis and has aided the identification of residues important for the synthesis of unnatural nucleic acid polymers

The non-geometric ̄P S wave in high-resolution seismic data: observations and modelling

In data from a high-resolution seismic survey conducted over a near-surface environment consisting of homogeneous soft clay, we consistently observe a distinct seismic phase arriving between the direct compressional wave and the Rayleigh wave. This phase is characterized by high amplitudes at near offsets and a phase velocity corresponding to about twice the shear wave velocity. Based on analytical and numerical analyses, this signal could be unambiguously identified as a non-geometric wave, which is excited if the source is located near the Earth's surface and the Poisson's ratio in the vicinity of the source is unusually high. To date there are only a few speculative observations of this particular non-geometric seismic wave phenomenon. However, given the commonly very high Poisson's ratio of surficial materials, we expect this phase to be present, albeit unidentified, in many near-surface seismic surveys. The presence of this non-geometric wave increases the complexity of the seismic record, and failure to identify it may result in misinterpretations, particularly of high-resolution seismic reflection data as well as of shear wave and surface wave data. Potential applications of this seismic phase may arise from its high sensitivity to the shear wave velocity in the immediate source regio