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"Skinner, Joseph (Joseph Edward)"
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The invention of greek ethnography
This thesis is a study of the origins and development of thought, Greek identity and Great Historiography. An introductory chapter outlines the problems, namely that current thinking on the way Greek ethnography and identity came into being has yet to take full account of recent advances in ethnographic and cultural studies, many of which have significant ramifications for our understanding of the social and intellectual milieu from which Great Historiography would eventually emerge. Chapter II conducts a broad census of the ethnographic imaginaire prior to the Persian Wars in order to challenge the prevailing orthodoxy that ethnographic interests were hazy and insubstantial prior to Xerxes’ invasion of Greece – invariably conceived as an unprecedented clash of civilisations and cultures. Chapter III builds on this argument, exploring the varied ways through which ethnographic interests became manifest and the manner in which knowledge and ideas relating to foreign lands and people were variously disseminated. Chapter IV shifts in focus to examine how discourses of identity and difference might have played out in a series of case studies: Olbia and its environs, the southernmost tip of the Italian peninsular (S. Calabria) and the imagined centres of Delphi and Olympia. A concluding chapter takes us forward in time to suggest ways modern preconceptions and concerns have structured the manner in which Greek ethnography and identity are framed and conceptualised. Particular emphasis will be placed on the attitudes and opinions that underpinned Felix Jacoby’s Die Fragmente der Griechische Historiker: a monumental work that played a key role in defining ethnography as genre. The implications thus posed for current understanding of the nature and origins of Great Historiography will then be explored.
Dissertation
Non-invasive Reversible Software-based Configuration of a Clinically Used Linear Accelerator for Preclinical Electron FLASH Radiobiology
Configuring clinical linear accelerators (linacs) for ultra-high dose rate (UHDR) electron experiments typically requires invasive hardware manipulation and/or irreversible manufacturer modifications, limiting broader implementation. We present an independently developed UHDR electron configuration of a clinical TrueBeam linac that allows reversible switching between preclinical UHDR and conventional (CONV) modes using only non-invasive software settings. UHDR mode was achieved via service mode software with RF and beam current settings typical of a photon beam, the photon target and monitor chamber retracted, and a clinically unused low-energy scattering foil inserted. An external AC current transformer (ACCT) for beam monitoring, anatomy-specific collimator, and sample holder were mounted on the accessory tray, with external ion chamber in solid water for exit dose monitoring. Percent depth dose (PDD) was measured for UHDR and CONV beams. Dose-per-pulse (DPP) was varied by adjusting gun voltage and quantified with radiochromic film at different source-to-surface distances (SSD). Beam profiles assessed dose uniformity and usable field size. Dose calibration was established between film, ACCT, and ion chamber, and day-to-day reproducibility was tested. PDD confirmed similar energies for UHDR (12.8MeV) and CONV (11.9MeV) beams with matching profiles through mouse thickness. Maximum DPP exceeded 0.5Gy, reaching ~1.5Gy for collimated in vivo setups and ~0.7Gy at extended SSD for tissue culture. Field flatness and symmetry were maintained, supporting organ-specific irradiations and up to 5cm fields for culture. Calibration showed strong linearity across detectors, and output variation was <4%. We demonstrated accurate, reproducible UHDR delivery on a widely available clinical linac with no invasive hardware manipulation, enabling preclinical FLASH research on a clinical treatment machine.
Journal Article
Multi-Institutional Audit of FLASH and Conventional Dosimetry with a 3D-Printed Anatomically Realistic Mouse Phantom
We conducted a multi-institutional audit of dosimetric variability between FLASH and conventional dose rate (CONV) electron irradiations by using an anatomically realistic 3D-printed mouse phantom. A CT scan of a live mouse was used to create a 3D model of bony anatomy, lungs, and soft tissue. A dual-nozzle 3D printer was used to print the mouse phantom using acrylonitrile butadiene styrene ($~1.02 g/cm^3$) and polylactic acid ($~1.24 g/cm^3$) simultaneously to simulate soft tissue and bone densities, respectively. The lungs were printed separately using lightweight polylactic acid ($~0.64 g/cm^3$). Hounsfield units (HU) and densities were compared with the reference CT scan of the live mouse. Print-to-print reproducibility of the phantom was assessed. Three institutions were each provided a phantom, and each institution performed two replicates of irradiations at selected mouse anatomic regions. The average dose difference between FLASH and CONV dose distributions and deviation from the prescribed dose were measured with radiochromic film. Compared to the reference CT scan, CT scans of the phantom demonstrated mass density differences of $0.10 g/cm^3$ for bone, $0.12 g/cm^3$ for lung, and $0.03 g/cm^3$ for soft tissue regions. Between phantoms, the difference in HU for soft tissue and bone was <10 HU from print to print. Lung exhibited the most variation (54 HU) but minimally affected dose distribution (<0.5% dose differences between phantoms). The mean difference between FLASH and CONV from the first replicate to the second decreased from 4.3% to 1.2%, and the mean difference from the prescribed dose decreased from 3.6% to 2.5% for CONV and 6.4% to 2.7% for FLASH. The framework presented here is promising for credentialing of multi-institutional studies of FLASH preclinical research to maximize the reproducibility of biological findings.
Journal Article
