Insulin-like 6 immunoreactivity (irINSL6) was detected in Leydig cells of the mouse testis. In the brain, labeled somata were detected mainly in the caudal hypothalamus and midbrain. Double labeling the brainstem sections revealed that irINSL6 somata were 5-hydroxytryptamine (5-HT) positive. The presence of irINSL6 in discrete populations of hypothalamic and brainstem neurons and in Leydig cells of the testis suggests a diverse biological function of this novel peptide.

The relative fission yields of the isotopes of krypton and xenon have been determined mass spectrometrically. Abnormal fission yields, resulting in fine structure in the mass fission yield curve, have been found in both mass ranges. A shift of the fine structure to lower masses has been observed in going from U^235 + n fission to U^238 + n fission. From this shift in fine structure, it has been possible to determine the proportion of U^235 and U^236 neutron fission that have occurred in the sample. Evidence is presented to show that the observed fine structure and the shift in this fine structure is the result of a combination of two effects involved the extra stability of closed neutron shells of 50 and 82 neutrons which fall in the Kr and Xe ranges respectively. The capture of thermal neutrons by Xe^135, which modifies the fission yields in the 135 and 136 mass chains, has been studied so that the observed fission yields at these masses may be suitably corrected. Finally, the branching ratio between the isomeric states of Kr^85 and the half-life of the long-lived isomer have been re-determined and found to be 0.29 and 10.27 ± 0.18 yrs. respectively. / Thesis / Doctor of Philosophy (PhD)

The indirect effect of atmospheric aerosol on climate remains a large source of uncertainty in anthropogenic climate change prediction. An important fraction of this uncertainty arises from the impacts of organic aerosol on cloud droplet formation. Conventional thinking says that organic aerosol hygroscopicity, typically represented by the hygroscopicity parameter κ, increases with oxidation, most commonly represented by the oxygen to carbon ratio of the aerosol, O:C. Furthermore, these quantities are expected to increase as aerosol volatility decreases. Results indicate that the link between organic aerosol hygroscopicity and oxidation is not always straightforward, and in some cases, the average carbon oxidation state OSc appears to be a better indicator of oxidation than the oxygen to carbon ratio, O:C. In chamber and ambient studies, the least volatile fraction of the aerosol also appeared to be the least hygroscopic, contradictory to current thinking; however, in both cases, thermally-denuded aerosol showed greater oxidation, in terms of OSc, than non-denuded aerosol. When these findings are placed in the context of numerous published studies from a variety of different environment, the overall trend of increasing organic hygroscopicity with O:C still holds. This is also true for volatilized aerosol, though the magnitude of organic hygroscopicity is generally lower than that of non-denuded aerosol.

published_or_final_version / abstract / Physiology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Physiology / Master / Master of Philosophy

published_or_final_version / abstract / Physiology / Master / Master of Philosophy

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

In the framework of active galactic nuclei (AGNs), a galaxy’s supermassive black hole is surrounded by a dusty torus whose clumpy configuration allows for either direct or obscured views toward the central engine. Viewing AGNs from different angles gives rise to a variety of AGN classifications; for example, the generic Type 1 AGN class requires the detection of optically broad emission lines, which arise from quickly moving material within the torus, whereas Type 2 AGNs lack these observations. While these viewing angles are not directly observable, synthetic torus models generated with CLUMPY provide a means to determine them along with other parameters that describe the nature and characteristics of the torus in general. Employing CLUMPY models with mid-infrared spectroscopic observations of a large sample of both Type 1 and Type 2 AGNs allows us to acquire a further understanding of the clumpy torus structure and its viewing angles.

Recent research has lead to the possible discovery of a new class of gamma-ray emitting ac- tive galactic nuclei (AGN). These objects – the very radio-loud narrow-line Seyfert 1 galaxies (NLSy1s)– demonstrate observational features suggesting that they are similar to blazars. One of the key characteristics of blazars is the presence of high-amplitude optical microvariability. While this phenomenon has been investigated in individual objects, no study of the intra-night variability of radio-loud NLSy1s as a class has previously been available. This dissertation presents a sys- tematic search for optical variability in a sample of 33 radio-loud NLSy1s. It was found that 26 objects demonstrated microvariations. However, only 9 objects did so with duty cycles comparable to blazars, and only 7 of these 9 objects — J0706+3901, J0849+5108, J0948+0022, J1246+0238, PKS 1502+036, J1644+2619, and IRAS 20181-2244 — demonstrated microvariability at compa- rable amplitudes. Two objects stand out as exceptional sources. J0849+5108 was found to have a duty cycle of ~90% and was observed to undergo an enormous 4-magnitude optical flare in a two-month time span. The object has not been reported to have undergone such an event since 1975. The second object, J0948+0022, is the class prototype. High cadence data indicates that J0948+0022 has a remarkably rapid doubling time scale of ~40 minutes, and it was seen to vary by over 0.9 magnitudes within an individual night. Attempts to correlate microvariability to radio loudness, gamma-ray loudness, and other parameters were largely unsuccessful. However, it was found that only radio-loud NLSy1s that were detected at gamma-ray energies demonstrated microvariability at blazar-like duty cycles. Additionally, an analysis of the frequency of microvariations at various amplitudes suggests that the sample of radio-loud NLSy1s presented in this study share a parent population identical to low energy peaked BL Lac-type (LBL) blazars. This is in agreement with the work of astronomers such as Abdo et al. 2009, who have created spectral energy distributions for a few radio-loud NLSy1s and found them to resemble those of LBLs. Blazar-like variability was found in multiple objects with radio loudnesses of log(R) < 2, suggesting that even moderately radio-loud NLSy1s may be blazar-like objects.

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