Browsing by Subject "Automatic"
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Item Restricted Automatic Modernism: Habit, Embodiment, and the Politics of Literary Form(2012) Wientzen, TimothyLiterary modernism followed a century during which philosophical speculations about the mechanistic basis of human life found experimental validation in the work of physiologists, who stressed the power of environment to shape and delimit thought and action. By the late 19th century, the hypothesis that humans were "automata," as Descartes had conjectured, began to seem much more than philosophical speculation, as statesmen and industrialists appropriated blueprints of the human machine originally mapped by the sciences. So dominant was the conjunction of politics and habit that, writing in 1890s, the American psychologist William James would call the automatic operations of body and mind the very engine of political life: "Habit," he declared, "is the enormous fly-wheel of society, its most precious conservative agent. It alone is what keeps us all within the bounds of ordinance, and saves the children of fortune from the envious uprisings of the poor." But James was only anticipating the wide range of thinkers who would associate physiological automatism with politics in the coming years. By century's end, the belief that habit determined social action and circumscribed individual volition was to find wide currency in a variety of cultural fields, including literary modernism.
Situating literary modernism in relation to this emergent sense of political modernity, Automatic Modernism argues that modernists reconfigured the discourse of automatism for political and aesthetic ends. Wary of the new political environment in which government, political parties and industry exploited the science of conditioned reflex to ensure automatic responses from docile subjects, writers of this period turned to the resources of literature in order to both disrupt the clichés of thought and action enforced by environmental stimuli and to imagine forms of politics adapted to the physiologically automatic body. Looking in particular at the fiction and non-fiction work of D. H. Lawrence, Wyndham Lewis, Rebecca West, and Samuel Beckett, this dissertation attempts to understand the recurrent equation of automatic behavior and twentieth-century modernity. Even as modernists vigorously rejected habitual behavior as the very element of twentieth century life that imperiled authentic art and social belonging, they forged alternative notions of bodily being, investing in the potentialities of human automatism as the basis of aesthetic possibility and social coherence. The formal experiments of these modernists emerge, then, as efforts to foreground, manipulate, rupture, and mimic the political habits of readers.
Item Open Access Automatic Volumetric Analysis of the Left Ventricle in 3D Apical Echocardiographs(2015) Wald, Andrew JamesApically-acquired 3D echocardiographs (echoes) are becoming a standard data component in the clinical evaluation of left ventricular (LV) function. Ejection fraction (EF) is one of the key quantitative biomarkers derived from echoes and used by echocardiographers to study a patient's heart function. In present clinical practice, EF is either grossly estimated by experienced observers, approximated using orthogonal 2D slices and Simpson's method, determined by manual segmentation of the LV lumen, or measured using semi-automatic proprietary software such as Philips QLab-3DQ. Each of these methods requires particular skill by the operator, and may be time-intensive, subject to variability, or both.
To address this, I have developed a novel, fully automatic method to LV segmentation in 3D echoes that offers EF calculation on clinical datasets at the push of a button. The solution is built on a pipeline that utilizes a number of image processing and feature detection methods specifically adopted to the 3D ultrasound modality. It is designed to be reasonably robust at handling dropout and missing features typical in clinical echocardiography. It is hypothesized that this method can displace the need for sonographer input, yet provide results statistically indistinguishable from those of experienced sonographers using QLab-3DQ, the current gold standard that is employed at Duke University Hospital.
A pre-clinical validation set, which was also used for iterative algorithm development, consisted of 70 cases previously seen at Duke. Of these, manual segmentations of 7 clinical cases were compared to the algorithm. The final algorithm predicts EF within ± 0.02 ratio units for 5 of them, and ± 0.09 units for the remaining 2 cases, within common clinical tolerance. Another 13 of the cases, often used for sonographer training and rated as having good image quality, were analyzed using QLab-3DQ, in which 11 cases showed concordance (± 0.10) with the algorithm. The remaining 50 cases retrospectively recruited at Duke and representative of everyday image quality showed 62% concordance (± 0.10) of QLab-3DQ with the algorithm. The fraction of concordant cases is highly dependent on image quality, and concordance improves greatly upon disqualification of poor quality images. Visual comparison of the QLab-3DQ segmentation to my algorithm overlaid on top of the original echoes also suggests that my method may be preferable or of high utility even in cases of EF discordance. This paper describes the algorithm and offers justifications for the adopted methods. The paper also discusses the design of a retrospective clinical trial now underway at Duke with 60 additional unseen cases intended only for independent validation.
Item Open Access Dose-Guided Automatic IMRT Planning: A Feasibility Study(2014) Sheng, YangPurpose: To develop and evaluate an automatic IMRT planning technique for prostate cancer utilizing prior expert plan's dose distribution as guidance.
Methods and Materials: In this study, the anatomical information of prostate cancer cases was parameterized and quantified into two measures: the percent distance-to-prostate (PDP) and the concaveness angle. Based on these two quantities, a plan atlas composed of 5 expert prostate IMRT plans was built out of a 70-case pool at our institution using k-medoids clustering analysis.
Extra 20 cases were used as query cases to evaluate the dose-guided automatic planning (DAP) scheme. Each query case was matched to an atlas case based on PTV-OAR anatomical features followed by deformable registration to enhance fine local matching. Using the deformation field, the expert dose in the matched atlas case was warped onto the query case, creating the goal dose conformal to the query case's anatomy. Dose volume histograms (DVHs) objectives were sampled from the goal dose to guide automatic IMRT treatment planning. Dosimetric comparison between DAP plans and clinical plans were performed.
Results: Generating goal dose is highly efficient by using MIMTM workflows. The deformable registration provides high-quality goal dose tailored to query case's anatomy in terms of the dose falloff at the PTV-OAR boundary and the overall conformity. Automatic planning in EclipseTM takes ~2.5 min (~70 iterations) without human intervention. Compared to clinical plans, DAP plans improved the conformity index from 0.85±0.04 to 0.88±0.02 (p=0.0045), the bladder-gEUD from 40.7±3.2 Gy to 40.0±3.1 Gy (p=0.0003), and rectum-gEUD from 40.4±2.0 Gy to 39.9±2.1 Gy (p=0.0167). Other dosimetric parameter is similar (p>0.05): homogeneity indices are 7.4±0.9% and 7.1±1.5%, for DAP plans and clinical plans, respectively.
Conclusions: Dose-guided automatic treatment planning is feasible and efficient. Atlas-based patient-specific dose objectives can effectively guide the optimizer to achieve similar or better plan quality compared to clinical plans.