Zugl.: Giessen, Universiẗat, Diss., 2008.

Zugl.: Giessen, Universiẗat, Diss., 2008.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 214-224). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Chicago, Department of astronomy and astrophysics, December 1999. / Includes bibliographical references. Also available on the Internet.

In this thesis, new high-angular resolution infrared and millimeter-wave spectroscopic observations of the enigmatic outflow activity associated with the luminous DR21 star-form ing region are presented and discussed. The intent is to use these observations to undertake a detailed investigation of the physical nature of the central driving engine and the related dynamical processes involved in collimating the hypersonic outflow gas. In the infrared, large-scale mapping and high-spectral resolution profile measurements of the vibrational H2 v = l-0 S(l) line are used to investigate the morphology and kinematic structure of the hot, dense gas that is collisionally excited behind fast shocks. The H2 emission delineates a highly-collimated pair of bipolar jets that extend over a projected distance of ~ 5 pc, centred on the DR21 molecular cloud core; this is undoubtedly the most luminous (in H2 line emission) and extended galactic outflow source yet discovered. Furthermore, the H2 line profiles at certain locations within the jets possess high-velocity wings that extend to beyond 100 km s-1 from the DR21 rest velocity. These observations pose interesting dynamical consequencies as at such high velocities H 2 should be entirely dissociated. In an attempt to derive the mass distribution and velocity structure of the molecular gas participating in the outflow, and hence the driving force and associated mechanical luminosity, detailed observations were also undertaken at millimeter-wavelengths in the CO J= 1 -0 and CS J = l-0 , J= 2-l lines. It is found that the DR21 outflow is considerably more massive and energetic than any other outflow source studied to date. Another feature unique to the DR21 region is the discovery of extended high-velocity CS emission that is dynamically associated with the outflow lobes and extends to a distance of ~ 3 pc from the cloud core; this component presumably originates from am bient gas that has been swept up and compressed by the outflow. The high-velocity CS may be overabundant by 2 orders of magnitude, in good agreement with current numerical models of post-shock chemistry. The CS observations further reveal the existence of an extremely massive, slowly rotating disc of high-density neutral gas that surrounds the central outflow source. It is most probable that the large momentum flux in outflow material derives from efficient mass-loss from the surface of this disc, mediated via a centrifugally propelled, magneto-hydrodynamic wind. An additional confinment mechanism is required to collimate the outflow at large distances from the flow origin. If this confinment is primarily pressure driven, then sudden changes in the ambient cloud pressure could induce a succession of oblique shocks within the outflow that may give rise to the periodic clumpy structure that characterizes the H2 emission-line jets. Other consequencies of the pressure-confinment mechanism are discussed and a broad resemblance to extragalactic radio jets is remarked upon.

Stars form from collapsing massive clouds of gas and dust. The UV and optical light emitted by a forming or recently-formed star is absorbed by the surrounding cloud and is re-radiated thermally at infrared and submillimetre wavelengths. Observations in the submillimetre spectrum are uniquely sensitive to star formation in the early Universe, as the peak of the thermal emission is redshifted to submillimetre wavelengths. The coolest objects in star forming regions in our own Galaxy, including heavily-obscured proto-stars and starless gravitationally-bound clumps, are also uniquely bright in the submillimetre spectrum. The Earth's atmosphere is mostly opaque at these wavelengths, however, limiting the spectral coverage and sensitivity achievable from ground-based observatories. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) observes the sky from an altitude of 40 km, above 99.5% of the atmosphere, using a long-duration scientific balloon platform. BLAST observes at 3 broad-band wavelengths spanning 250-500 micron, taking advantage of detector technology developed for the space-based instrument SPIRE, scheduled for launch in 2008. The greatly-enhanced atmospheric transmission at float altitudes, increased detector sensitivity and large number of detector elements allow BLAST to survey much larger fields in a much smaller time than can be accomplished with ground-based instruments. It is expected that in a single 10-day flight, BLAST will detect ~10000 extragalactic sources, ~100 times the number detected in 10 years of ground-based observations, and 1000s of Galactic star-forming sources, a large fraction of which are not seen by infrared telescopes. The instrument has performed 2 scientific flights, in the summer of 2005 and winter of 2006, for a total of 16 days of observing time. This thesis discusses the design of the instrument, performance of the flights, and presents the analysis of 2 of the fields observed during the first flight. A failure in the optical system during the first flight precluded sensitive extragalactic observations, so the majority of the flight was spent observing Galactic targets. We anticipate exciting extragalactic and Galactic results from the 2006 data. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Star cluster formation involves the conversion of molecular gas into stars inside giant molecular clouds (GMCs). Such a process involves many dynamical evolution mechanisms, including mergers between smaller star clusters (subclusters) on which we focus in this thesis. We take results of simulations performed by Howard et al. 2018 (H18) which found that young massive cluster (YMC) formation is heavily dependant on the process of subcluster mergers, and we simulate said mergers at higher resolution. Subclusters inside such GMC simulations are modelled using the sink particle prescription which does not resolve individual star particles or gas parcels inside the subcluster they represent. We employ a more controlled method in simulating subcluster mergers to better understand the response of the stellar and gas components of a subcluster from the merger process. To do this, we take the parameters of the sink particles created in H18 and set up spheres of stars and gas. We use the AMUSE framework to couple the N-body evolution of the stars to the smoothed particle hydrodynamics (SPH) evolution of the gas such that both components of a given cluster can realistically react to each other. We model 15 of these mergers and find that once the velocity at which the two clusters collide (collisional velocity) exceeds $\approx 10$kms$^{-1}$, the resultant cluster is not monolithic (i.e. it still contains two separate stellar components) while all other simulations merge into one monolithic stellar and gas component cluster. We also find that, regardless of the collisional velocity of masses of the component clusters, all resultant clusters lose a fraction of their stellar and gas mass. This fraction is directly proportional to the collisional velocity and is a discrepancy between the sink particle prescription (where all mass is contained inside a constant sink particle accretion radius) and real cluster mergers. A further discrepancy we find is that all simulations result in a cluster whose outermost regions are expanding and that the rate of this expansion is somewhat proportional to the collisional velocity of the merger. These results point to the inaccuracy of the sink particle prescription and allow us to develop tools to improve on it in future simulations. Next, we fit commonly used analytical density profiles to both the stellar and gas component of our resultant clusters and find that, while they do not provide particularly excellent fits, they provide constraints on what is an acceptable fit. Lastly, we analyze the amount by which gas with potentially star forming densities increase due to the merger and we find that all mergers increase their star forming gas mass fraction by roughly 50 per cent implying that mergers may be an effective tool for triggering star formation. / Thesis / Master of Science (MSc)

This dissertation studies the effect of star power among physicians on the diffusion of a medical technology. Studies of the diffusion of medical technologies document institutional and market level factors influencing diffusion rates and patterns. The role of the physician in the diffusion of medical technology in hospitals is not widely studied. This dissertation seeks to fill this gap. Certain "star" physicians and hospitals are recognized as highly attractive to patients. A star physician is defined as a physician who meets any of the following criteria: (i) completed residency training at top 30 ranked hospital, (ii) graduated from a top 30 medical school or (iii) is included in Castle & Connolly's Top Docs publications. A star hospital is defined as a member of the American Association of Medical Colleges' Council of Teaching Hospitals. Using quarterly data on all bariatric surgeries performed in the state of Pennsylvania from 1995 through 2007, I measure the effect of stars physicians and star hospitals on the diffusion of a surgical innovation in bariatric surgery called laparoscopic gastric bypass surgery. I use logistic and OLS regression to test for effects at both the hospital and physician level. At the hospital level, I find that having a star physician at a hospital raises the likelihood of that hospital diffusing laparoscopic gastric bypass from eleven percent to eighty-nine percent. I find that over the time period from first quarter 2000 to fourth quarter 2001, being a star hospital raises the likelihood of that hospital diffusing laparoscopic gastric bypass from thirteen percent to eighty-seven percent. At the physician level, the empirical results indicate that star physicians exert positive asymmetric influence on the adoption and utilization rates of non-stars at the same hospital. This dissertation supports earlier work in technology diffusion by finding a positive influence from key individuals. It adds to the literature on medical technology diffusion by testing a new data set for a chronic disease treatment. / Economics

Yes / Heritage (and by extension, archaeology) is an important part of the Star Wars universe. Both the Jedi and the Sith share teachings revolving around sites and artifacts important to their heritage and identities, and archaeologists like Chelli Aphra have played important roles in the development and maintenance of heritage. However, the politicization of sites and artifacts by many groups and individuals has also served as motivation behind significant schisms, battles, imperialism, and resistance. As professional archaeologists, we have become familiar with the ways these themes are appearing within our real world discipline as well. This paper will broadly examine the roles that archaeology and heritage play in the Star Wars universe. Using examples from both canon media and expanded universe (now referred to as Legends) lore, this paper will explore the ways in which political factions manipulate and weaponize heritage and archaeology to their benefit. These examples will then be discussed within real world contexts to illustrate how Star Wars is ultimately a perfect encapsulation of the political powers inherent in archaeology and heritage studies, and the resistance to the manipulation of these fields.

This thesis examines in detail the construct we term the ‘theatre star’. It aims to investigate how transnational theatre stars in Australia and New Zealand in the early-twentieth century validated their professional eminence, social cachet and public adulation through the strategic development and manipulation of their on and off-stage personae and mediated afterlives. Rather than focus on the theatre star as a solitary icon, my theoretical approach examines the star as a valuable partner – social, professional and cultural – within the infrastructure of the theatre industry. While much research has been done to explicate theatre performers’ burgeoning professional status and appeal as charismatic personalities and performance specialists, particularly in British and American contexts in the eighteenth and nineteenth centuries, there is little investigation on the constructed identity of the star performer of early-twentieth-century Australasian theatre. The conceptual model of ‘imbricated identity’ theorized in this study seeks to mark a shift in the field of theatre historiography. It articulates an intertextuality of performance that reaches beyond that defined by Marvin Carlson as ‘ghosting’ inherent in theatre praxis, and by Jacky Bratton as ‘intertheatricality’. I propose that the validation of ‘personality’ – the mysteriously elusive and ‘uncanny appeal’ or ‘x’ factor – is only one dynamic explanation for the theatre star’s popular success. The term ‘imbricated identity’ is used to describe the cultural accretion of interleaved and overlapping depictions of the star’s identity: theatrical representations, civic persona, private self for public consumption, and posthumous legacy. These delineated images operate coterminously. They strategically coalesce and sometimes conflate, informing discursive framings of the star’s identity as variously invested in by the artiste, and his/her symbiotic partnerships with theatre management, media, spouse/s, family and the public. During the early-twentieth century the theatre star’s constructed identity became necessarily more complex with the advent of modernity’s mass-mediated communications. Printed media, radio and film increasingly revealed information about stars’ public and private lives. Case studies of Nellie Stewart, Ada Reeve, Madge Elliott and Cyril Ritchard are used to explicate how theatre performers fashioned and articulated their distinct star images. All are performers identified as ‘Australian’ at some phase of their careers, who also maintained strong international profiles, particularly in New Zealand, England and America. They performed variously in entertainments such as dance, drama, vaudeville and revue, radio, film and television. The work of these chosen subjects traverses paradigms of high and low culture: boundaries that became increasingly more fragile with modernity’s exchange and fusion of culture and commerce. The star’s image and cultural status are unstable and rely upon contextualization syncretized by the star and theatre management, professional colleagues, journalism, fans and audiences. The public, private, and professional partnerships of my chosen subjects had a significant impact on their acculturation as Australian stars on the transnational stage, and their mediated afterlives continue today to invite multiple readings of star personae.