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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.
161

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

Ahmadi, Sara January 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.
162

Mechanisms of Star Formation Suppression in the Strongly Barred Galaxy NGC1300 / 棒渦巻銀河 NGC1300 における星形成抑制メカニズムの解明

Maeda, Fumiya 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23013号 / 理博第4690号 / 新制||理||1672(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 太田 耕司, 教授 長田 哲也, 准教授 栗田 光樹夫 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
163

EDGES: Radial Star Formation Histories in Nearby Galaxies NGC4102 and UGC07608

Cox, Isaiah S, Anderson, Kristin R, Bran, Loius M, Drake, Carolyn L, Lee, Nathan J, Pilawa, Jacob D, Slane, Frederick A, Soto, Susana, Jensen, Emily I, Sutter, Jessica S, Turner, Jordan A, Kobulnicky, Henry A, Dale, Daniel A 12 April 2019 (has links)
New deep ugr imaging was obtained on the Wyoming Infrared Observatory 2.3 meter telescope for NGC4102 and UGC07608, two galaxies in the Extended Disk Galaxy Exploration Science survey. These data are coupled with deep GALEX ultraviolet and Spitzer, WISE and Herschel infrared imaging to study the radial variations in the spectral energy distributions. Results from the CIGALE SED modeling software are presented, including trends in the galaxy star formation histories.
164

Bioinformatic tool developments with applications to RNA-seq data analysis and clinical cancer research

Haas, Brian John 18 February 2022 (has links)
Modern advances in sequencing technologies have enabled exploration of molecular biology at unprecedented scale and resolution. Transcriptome sequencing (RNA-seq), in particular, has been widely adopted as a routine cost-effective method for assaying both genetic and functional characteristics of biological systems with resolution down to individual cells. Clinical research and applications leveraging these technologies have largely targeted tumor biology, where transcriptome sequencing can capture tumor genetic and epigenetic characteristics and aid with understanding the etiology or guide treatments. Specialized computational methods and bioinformatic software tools are essential for processing and analyzing RNA-seq to explore various aspects of tumor biology including driver mutations, genome rearrangements, and aneuploidy. With single cell resolution, such methods can yield insights into tumor cellular composition and heterogeneity. Here, we developed methods and tools to support cancer transcriptome studies for bulk and single cell tumor transcriptomes, focusing primarily on fusion transcript detection and predicting large-scale copy number alternations from RNA-seq. These efforts culminated in the development of STAR-Fusion for fast and accurate detection of fusion transcripts, FusionInspector for further characterizing predicted fusion transcripts and discriminating likely artifacts, and TrinityFusion for de novo reconstruction of fusion transcripts and tumor viruses. We also developed advanced methods for predicting copy number alterations and subclonal architecture from tumor and normal single cell RNA-seq data, as incorporated into our InferCNV software. In addition to these bioinformatic method and software developments, we applied our fusion detection methods to thousands of tumor and normal samples and gain novel insights that should further help guide researchers with clinical applications of fusion transcript discovery.
165

A History of Finance in the Star Valley Public Schools From 1925 to 1955

Papworth, Harold R. 01 May 1956 (has links)
With the rapid changes in American education and the educational financing that is necessary for these changes, school finance is perhaps one of the most dynamic forces in education today.
166

Dynamical Modification of a Primordial Population of Binaries in Simulations of Star Cluster Formation / Primordial Binaries and Star Cluster Formation

Cournoyer-Cloutier, Claude January 2021 (has links)
Most star formation in galaxies takes place in embedded clusters, within Giant Molecular Clouds (GMCs). Stars also generally form as part of binary star systems, with almost all massive stars having at least one close companion. Binaries shape the physical properties of older star clusters by setting their central density and ejecting low-mass stars, but also play a role during cluster formation by modifying the mechanical and radiative feedback from massive stars and shedding enriched material in the cluster’s gas reservoir. Conversely, dynamical interactions between stars in dense stellar environments are known to form, modify, and destroy binary systems. In consequence, the populations of binaries observed in the Galactic field and in old stellar clusters are understood to be shaped by a combination of the physics of star formation and subsequent dynamical interactions in embedded clusters, although the relative importance of these processes remains unknown. In this thesis, we implement a prescription for an initial population of binaries in the coupled N-body and radiation hydrodynamics star cluster formation code Torch, and investigate how this initial population is modified in the earliest stages of cluster formation, while gas and stars coexist. As an ansatz for the initial population of binaries, we use the properties of main-sequence binaries in the Galactic field. We first perform a suite of simulations initialized from a 10^4 M⦿ cloud, in which the simulations only differ by their stellar content (i.e. presence or absence of an initial population of binaries, and stochasticity of star formation). We compare the populations of binaries identified 1.2–2 Myr after the onset of star formation and find that an initial population of binaries is needed at all masses to reproduce the multiplicity fraction observed in main-sequence stars. We also show that this initial population is modified in a systematic manner before the effects of feedback from massive stars shape the gas. We further find evidence of both preferential formation and preferential destruction of binaries via dynamical interactions. The net effect of these interactions shifts the distributions of primary masses and semi-major axes to lower values, and the distributions of mass ratios and eccentricities to larger values. In a second time, we perform simulations with different virial parameters and initial turbulent velocity patterns, and find that the trends previously identified are robust to those changes in our initial conditions. We however find that both the virial parameter and the initial turbulent velocity pattern have a strong influence on the star formation rate, and therefore on the rapidity with which the distributions are modified. We conclude that dynamical interactions in embedded clusters are important for shaping the populations of binaries observed in the MilkyWay, thus opening the floor to future investigations of the impact of binaries on star cluster formation. / Thesis / Master of Science (MSc)
167

Multi-wavelength studies of the interstellar medium and star formation in nearby galaxies

Chown, Ryan January 2021 (has links)
In this thesis I investigate three key questions about the interstellar medium (ISM) and star formation in nearby galaxies. The first question is, “how do bars and galaxy interactions affect the distribution of cold gas and the level of central star formation in galaxies?” I use publicly-available spatially-resolved images of CO(1-0) emission in a sample of 126 nearby galaxies from the Extragalactic Database for Galaxy Evolution (EDGE) survey to measure molecular gas concentrations, and I use spatially-resolved optical spectroscopy from the Calar Alto Legacy Integral Field Area (CALIFA) survey to measure the level of central star formation enhancement. I find that gas concentration and the level of central star formation enhancement are positively correlated in barred galaxies but not in unbarred galaxies, and that interacting galaxies show signs of a correlation but not in all cases. These results indicate that central star formation enhancement occurs only in barred galaxies and interacting galaxies with high gas concentrations, which supports theories of bar- and interaction-driven galaxy evolution. The second question is, “what is the relationship between mid-infrared (MIR) emission and molecular gas at spatially-resolved scales in galaxies?” I extend previous work, which found a tight correlation between global MIR emission in the Wide-field Infrared Survey Explorer (WISE) 12 micron band and CO emission from single-dish radio telescopes, to spatially-resolved scales using EDGE CO data smoothed to WISE 12 micron resolution. I find that these quantities are tightly correlated at ~kiloparsec scales, and that the correlation shows offsets from galaxy to galaxy. I find that these offsets are explained best by differences in the level of global near- and far-ultraviolet emission, and that the 12 micron-CO correlation is the strongest of all the resolved correlations that I considered. These results suggest that there is a tight physical link between WISE 12 micron emission and CO emission on kiloparsec scales, possibly due to a connection between polycyclic aromatic hydrocarbons (PAHs, which dominate the 12 micron emission) and molecular gas. My findings can be used to estimate resolved CO emission based on (easily obtained) WISE 12 micron images and a small number of global multi-wavelength measurements. These results also motivate further work exploring the CO-PAH connection in more diverse conditions and at higher resolution. Finally, the third question is, “what is the ISM content of red star-forming galaxies?” In comparison to blue star-forming galaxies (“blue actives”) which lie on or above the star-forming main sequence (SFMS), these “red misfits” tend to lie on or slightly below the SFMS. I find that the main property other than colour that differentiates red misfits from blue actives is their low gas mass fractions. The gas depletion times and gas-to-dust ratios are similar between these populations. My results indicate that the star formation of red misfits is in the act of quenching. The unifying theme of each of these projects is the approach: studying key questions in nearby galaxies based on their molecular gas content along with other multi-wavelength data, at a variety of resolutions. This approach is enabled by large publicly available multi-wavelength data sets at a variety of physical resolutions. Surveys of the global gas content of galaxies with accompanying multi-wavelength data will always be larger, and will continue to be an important reference for smaller resolved surveys. I hope that this thesis serves as a useful comparison between the science that can be done on both global and resolved scales, and will motivate future work on the connection between the ISM and star formation in nearby galaxies. / Thesis / Doctor of Science (PhD)
168

Estimating Properties of a Young Pulsar through X-ray Observations - An Investigation of Parameter Dependence

Ali, Lurin January 2022 (has links)
Studying the properties of newborn neutron stars is a complicated matter since they cannot be directly observed. Neutron stars are born when some massive stars go supernova (SN), where the expelled material from the explosion goes on to shield the young neutron star from our view by absorbing its radiation. To estimate properties such as their flux, luminosity and magnetic field strength, upper limits can be found by modeling the emission and absorption and then performing spectral fitting. The assumptions made when modeling can cause the results to differ, this thesis investigates which parameters in the model have the most impact by analysing an X-ray observation of SN 1909A. The varied model parameters are the photon index of the neutron star emission, the density of the SN ejecta, and the composition of the ejecta material. The density can vary depending on the line of sight since SN explosions are asymmetrical, and it is found that this parameter carries most significance, with maximal result variations of about 55% for most ejecta compositions. The least significant parameter is the assumed photon index of the emission from the neutron star, this is found to only cause maximal variations of around 24%. Furthermore, the upper limits on the total luminosity computed by assuming different model parameters, differ by a factor 2.5 at most. The minimum upper limit to the total luminosity of the neutron star of SN 1909A is found to be L_min = 3.6 * 10^6 L⊙ and the corresponding relation between its rotational period and magnetic field is B < 1.88 * 10^20 P^2 G s^-1.
169

"This is the Way": Gender Representation in Disney's The Mandalorian

Solorio, Brooke 09 December 2022 (has links)
When Disney released The Mandalorian, it quickly became the top show on its highly popular streaming platform. As with all media wielding this level of exposure, it is important to closely examine its content for depictions of peoples including females. In accordance with Sandra Bem's gender schema theory, the implicit messaging in this series can influence the formation of people's mental shortcuts about what it means to be female. This study employs content analysis to illuminate the portrayal of physical and non-physical attributes of the women present in the two seasons existing at the time of this study. Results reveal significant diversity in areas such as body type, character role, age, and appearance; especially when compared to the show's predecessors. However, while Disney has publicly pronounced ethnic diversity a priority, one could argue that The Mandalorian possesses only a surface appearance of ethnic diversity. This is because many of the actresses are either fully white or mixed with white--the race that has historically dominated our screens. Disney has taken steps in the right direction with The Mandalorian but would benefit from a closer content assessment if they seek to retain their consumer's trust long-term.
170

Neutron Star Cooling

Glen, William Thomas Graham 10 1900 (has links)
<p> To determine the detectability of thermal radiation from the surface of a neutron star, the surface temperature as a function of time is needed. To find this, the surface temperature as a function of core temperature is found; this ratio depending on temperature, stellar mass, and magnetic field strength. The energy loss rates from photon emission and neutrino emission are calculated, along with the specific heat of the star; the latter two quantities depending on the core temperature. The surface temperature as a function of time is then calculated for various combinations of the variable parameters: stellar mass, equation of state, magnetic field, superfluidity, and pion cutoff density. Finally, a calculation of the detectability (distance vs. age) of a typical neutron star is made, using the estimated capabilities of the X-ray telescope on the Einstein Observatory.</p> / Thesis / Master of Science (MSc)

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