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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

"Playthings in the Margins of Literature": Cultural Critique and Rewriting Ideologies in Supernatural and Star Wars Fanfiction

Handley, Christine 03 September 2010 (has links)
Building on the questions of gender and sexuality proposed by the ethnographic analyses of first wave fanfiction criticism, I identify the ways in which fanfiction may function as a feminist response to the mainstream patriarchal culture of two media texts: the Star Wars films and the television series Supernatural. To frame this argument, I question the problematic associations of Henry Jenkins’s massively influential metaphor of fan writers as “poachers,” which implicitly supports Theodore Adorno and Max Horkheimer’s vision of the lack of critical engagement engendered by popular culture. In my discussion of this metaphor and the prevalent resistance/incorporation paradigm of fan/producer interaction, I expand critical and theoretical notions of dialogue and intertextuality in terms of fanfiction works, and propose a shift in terminology for my own and future examinations of fan culture.
132

Acceleration due to gravity on a rapidly rotating neutron star

AlGendy,Mohammad Unknown Date
No description available.
133

The star-formation history of massive galaxies

Schael, Anita M. January 2009 (has links)
This thesis presents multi-frequency data, galaxy identifications, estimated redshifts, and derived physical properties for the sub-millimetre source sample produced by the SCUBA HAlf Degree Extragalactic Survey (SHADES). SHADES is the largest, complete, sub-millimetre survey undertaken to date, and the aim of this work is to exploit this survey to study the evolution of sub-mm selected galaxies at high redshift, explore their possible connectionwith localmassive ellipticals, and to test current models of galaxy formation. The SHADES sample was selected from 850 micron images made with the submillimetre camera SCUBA at the James Clerk Maxwell Telescope. These submillimetre maps cover a total area of 720 arcmin2 split between two well-studied extra-galactic survey fields, the Lockman Hole East and the Subaru/XMMNewton Deep Field (SXDF). The resulting sample of 120 sub-millimetre sources is the focus of this thesis. Here the wealth of information provided by deep radio, optical, near-infrared and mid-infrared imaging of the two SHADES fields is exploited to complete the identification of the SHADES sample, and then to derive a robust redshift estimate for every sub-millimetre source. Where possible this is achieved from the optical+ infrared photometry using a new two-component redshift estimation code developed specifically to deal with starbursting galaxies with potentially highly stochastic star-formation histories. The effectiveness of this code is demonstrated via comparison with the small subset of SHADES source which possess robust spectroscopic redshifts. For those galaxies which are too faint for effective redshift constraints to be provided by the existing optical+infrared photometry, the information on the long-wavelength spectral energy distribution provided by the radio+submm photometry is utilised to provide cruder constraints or limits on redshift. The result is the first complete and unbiased estimate of the redshift distribution of the bright extragalactic sub-millimetre galaxy population. It is found that the brightest sub-mm sources are confined to the redshift range 2 < z < 4, while more moderate luminosity sources span the full range of redshift out to z ∼ 5. The fits to themulti-frequency photometry provided by the redshift estimation technique are also used to derive estimates of the stellar mass, and star-formation history of each SHADES galaxy. The average derived stellar mass is ∼ 3 × 1011 M⊙ and it is found that the violent starburst powering the sub-millimetre emission typically contributes less than 10% of the stellar mass of the galaxy which has been assembled prior to the “current” starburst event. The distributions of redshift, stellar mass, and star-burst ages are compared with the predictions of a range of galaxy models, including the suite of models originally used to motivate the SHADES survey in van Kampen et al. (2005), and themost recent incarnation of the Durhamsemi-analytic galaxy formationmodels described by Swinbank et al. (2008). It is found that the redshift distribution and sub-mmflux versus redshift for bright sub-mmgalaxies can be reproduced best by one of the van Kampen models, which is based on semi-analytic modelling with a Chabrier IMF. We can rule out the non-semi-analytic prediction models and the Durham semi-analytic model with a top-heavy IMF. However the stellar masses are systematically underpredicted by all of the models. Either the stellar masses derived from the SHADES data have been systematically over-estimated, or the models need to be modified (perhaps by the inclusion of AGN feedback) to allow larger galaxy masses to assembled prior to z ∼ 2. Finally, it is demonstrated that themass in place prior to the observed starburst cannot have been produced by an analogous super-burst at higher redshift, but rather requires to have been assembledmore gradually over a timescale of ∼ 1−2 Gyr. It is thus concluded thatmassive galaxies undergo theirmost violent phase of star formation at redshifts 2 < z < 4, but that the enormous starbursts which lead to detection in current sub-millimetre surveys can only take place in the potential well provided by an already massive galaxy. This supports a scenario in which bright sub-millimetre galaxies are indeed the progenitors of the massive elliptical galaxies found in the local Universe.
134

Statistics of YSO jets in the galactic plane from UWISH2

Ionnidis, G. January 2013 (has links)
In order to study jets and outflows from Young Stellar Objects (YSOs), I performed an unbiased search on a continuous 33 square degree sized region in Serpens and Aquila using data taken from the UWISH2 survey, which uses the 1-0 S(I) emission line ofH2 as a tracer. I identified 130 molecular hydrogen outflows from YSOs from which 120 (92 %) objects are new discoveries. Distances were measured by foreground star counts with an accuracy of25 %. Outflows were found in groups of 3 - 5 members with a size of about 5 pc. Groups were separated by about half a degree on the sky. About half of the objects were assigned with potential source candidates. Brighter MHOs had a higher probability to have a source candidate assigned to them. I find an over abundance of outflows with position angles between 1300 and 1500 which is almost perpendicular to the Galactic Plane. The fraction of parsec scale outflows is about 25 % which is more than twice compared to the one found in Orion A by Stanke et al. (2002) and Davis et al. (2009). The outflows are not able to provide a sufficient fraction of energy and momentum to support the turbulence levels in their surrounding molecular clouds. The typical dynamical jet age was of the order of 104 yrs, while groups of emission knots are ejected every 103 yrs. This indicates that low level accretion rate fluctuations and not Fu-Ori type events are responsible for the episodic ej ection of material. The luminosity distribution of the outflows shows a power law behaviour with N ex: LH;·9. The Milky Way star formation rate was estimated to more than 1.6 ± 0.4M0 yr-1 The Spectral Index Classification distribution plot of YSOs indicated that the number of outflows increases in line with a values and has a similar distribution to the one from Davis et al. (2009) from Orion A.
135

Role of Circulating Angiotensin II in Activation of Aldosterone production in the Central Nervous System

Ahmadi, Sara 30 June 2011 (has links)
Elevated circulating Ang II activates neurons in the forebrain cardiovascular regulatory areas to cause sympatho-excitation and hypertension. We hypothesized that circulating Ang II causes neuronal activation in the SFO and thereby activates efferent pathways to the PVN, and chronically causes activation of aldosterone production in magnocellular neurons in PVN and SON, which amplifies neuronal activation in the PVN and central sympatho-excitatory pathways. The aim of the present study was to determine the pattern of neuronal activation in forebrain nuclei by circulating Ang II and to elucidate where in the hypothalamus Ang II may stimulate aldosterone biosynthesis. Dose related effects of circulating Ang II on BP were first assessed. Wistar rats instrumented with telemetry probes were infused subcutaneously with Ang II 150 and 500 ng/kg/min for 14 days. The subcutaneous infusion of Ang II at 150 ng/kg/min increased blood pressure gradually up to 20 mmHg and at 500 ng/kg/min up to 60 mmHg. Ang II at 500 ng/kg/min increased plasma Ang II by 4-fold. To assess effects of circulating Ang II on CNS pathways, Wistar rats were implanted subcutaneously with minipumps infusing 150 and 500 ng/kg/min Ang II for 1, 4 and 14 days. Three patterns of neuronal activation were observed by sc infusion of Ang II. The SFO was activated during the first day and remained activated for 4 days, but at 14 days showed diminished activation. MnPO did not show significant activation during the first day but, after several days the activation was high and then less by 14 days. Parvocellular PVN (pPVN), magnocellular PVN (mPVN) and SON showed an initial activation that increased over time. Chronic intracerebroventricular infusion of an aldosterone synthase inhibitor or a mineralocorticoid receptor (MR) blocker attenuated the increase in Fra expression in PVN but not SON, and prevented the decrease in SFO after 14 days infusion of Ang II. A significant increase in mRNA expression of steroidogenic acute regulatory protein (StAR), a rate limiting enzyme in aldosterone production was found in glia cells of PVN and SFO assessed by rt-PCR after 3 days subcutaneous infusion of Ang II at 500 ng/kg/min. Total expression of aldosterone synthase (CYP11B2) mRNA was increased in SFO, MnPO, SON and PVN after 3 days of infusion of Ang II. After 14 days no significant changes were observed in the expression of StAR or CYP11B2 mRNA. In comparison, in adrenal StAR mRNA expression increased after 3 days but no longer after 14 days. In contrast, CYP11B2 mRNA expression in adrenal increased after both 3 and 14 days of infusion. These findings may support our hypothesis that chronic elevation of circulating Ang II increases neuronal activity in CVOs, presumably leading to activation of the PVN and SON to induce an increase in aldosterone production in magnocelular PVN and SON. In the second phase activation of CVOs appears to diminish, but an aldosterone-dependent amplifying mechanisms, causes sustained activation of the PVN and thereby hypertension.
136

Galaxy Formation at Redshift ~0.75: A Low Mass Survey & The Role of Environment

Greene, Chad January 2011 (has links)
The majority of galaxy formation studies which explore beyond local redshifts do not typically probe down to the dwarf galaxy stellar mass range of ∼ 10^9 Msun . Thus trends in the observed evolution or characteristics of galaxy formation at a particular epoch are based upon populations of massive galaxies. However the currently favored Λ-Cold Dark Matter (Λ-CDM) theory is based upon hierarchical clustering and merging of lower mass systems, which proceed to make the higher mass, complex morphology of galaxies we observe. Thus it is clear that within the dwarf galaxy mass regime there should be a significant phase of galaxy formation and evolution. This work aims to uncover the influence of local environment on the formation and evolution of dwarf and massive galaxies beyond local redshift, probing down to a mass range lower than that which has been explored by previous studies. A previously successful study titled the Redshift One LDSS-3 Emission line Survey (ROLES), released results for a redshift of z ∼ 1, which compared the [OII] luminosity and galaxy stellar mass functions ([OII] LF and GSMF respectively), star formation rate density (SFRD), and specific star formation rate (sSFR) relations, with a local SDSS dataset. This led to the expansion of the study to lower redshift (this work) which explored low stellar mass galaxies at a redshift of z ∼ 0.75. This follow-up study referred to as ROLES75 (z ∼ 0.75) targeted the same two deep fields explored by the z ∼ 1 study (GOODS-South, MS1054-03 FIRES), which have extensive public photometry. Low mass targets were selected for study by their K-magnitudes (22.5 < KAB < 24) leading to a dwarf mass range of 8.5 < Log(M∗/Msun) < 9.5, and which were most likely to be within our redshift range (0.62 < z < 0.885). Follow-up multi-object spectroscopy targeted the [OII]λ3727A emission line star formation tracer in these targets allowing us to identify and obtain secure spectroscopic redshifts, SED-fit stellar masses and observed [OII] luminosity calibrated star formation rates down to limits of Log(M∗/Msun) ∼ 8.85 and SFR ∼ 0.1 Msun/yr . Science results presented here are similar to those published by the ROLES z ∼ 1 study, however we also studied the influence of the high versus low density environment in which the galaxy populations reside. This study confirmed that while the [OII] luminosity was higher in earlier times, environment does not influence galaxy formation at z ∼ 0.75. The faint-end slope of the [OII] LF, α ∼ 1.25 measured here, is also observed to become increasingly more steep with increasing redshift. The [OII] luminous GSMF is observed to not have significantly evolved since z ∼ 2.75, confirming the result of the previous ROLES work. However the impact of environment on the GSMF is apparent in the high mass end where the imprint of structure from the CDFS field enhances the stellar mass function above the field population. There is also weak evidence of a bi-modal [OII] luminous GSMF indicated by an ‘upturn’ near ∼ 10^9 Msun in the low density field population. The SFRD at z ∼ 0.75 does not confirm the picture presented by the ROLES z ∼ 1 study where a constant scale factor was applicable to the local SDSS SFRD to obtain the z ∼ 1 SFRD. The SFRD in the high mass end at z ∼ 0.75 is lower than would be expected based upon a constant scale factor, while the low stellar mass end exhibits some consistency with this picture. In the high density environment, this dominant SFRD (over the low density field population) is driven by the high density [OII] luminous GSMF in the high stellar mass end, rather than through an enhancement of the SFR. The normalization of the sSFR − M∗ relation at z ∼ 0.75 is found to lie between those corresponding to z ∼ 1 and present day. There is a subtle ‘upturn’ in the sSFR − M∗ relation confirming this observation which was also present in the ROLES z ∼ 1 study but not present in the local SDSS sSFR − M∗ relation. The sSFR of active galaxies does not depend upon the local density in which they are forming, confirming the same conclusion based upon the [OII] LF. However, there is redshift evolution of the sSFR − M∗ relation with respect to local density. The high density sSFR − M∗ relation for star forming galaxies was dominant over its low density counterpart at early times, with the opposite the case at present day. There is suggestion of the crossover or rollover transition occurring at z ∼ 0.75.
137

Interindividueller Vergleich multifokaler Intraokularlinsen hinsichtlich Sehschärfe in der Ferne und Nähe, Lesegeschwindigkeit sowie Kontrastsehvermögen

Grolmus, Roman. January 2007 (has links)
Universiẗat, Diss., 2006--Giessen.
138

The economics of superstars and celebrities

Nüesch, Stephan January 2007 (has links)
Zugl.: Zürich, Univ., Diss., 2007
139

A comparative analysis of methods for calculating IOL power Ccombination of three corneal power and two axial length measuring techniques /

Stanbekova, Ainura. January 2008 (has links)
Tübingen, Univ., Diss., 2008.
140

Morphologische und physiologische Untersuchungen an transparenten und kataraktösen Linsen von Farm- und Wildlachsen /

Willeke, Katja. January 2008 (has links)
Zugl.: Berlin, Freie Universiẗat, Diss., 2008.

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