Substrate dependance, temperature dependance and temperature sensitivity and resolution of doped-silicon microcantilevers

This thesis aims to characterize microcantilevers with integrated heater-thermometers. This research concentrates on characterization for use in data storage, sensing, surface science, and nano-manufacturing. The rst objective seeks to understand the speci c thermal interactions between a heated microcantilever tip and various substrates. The experiments investigate thermal conductance, thermal time constant, and temperature-dependant adhesion force between and cantilever tip and substrates of silicon, quartz, and polyimide. The second objective is to utilize a heated microcantilever as a heater-thermometer. The experiments investigate the thermal calibration sensitivity and resolution under steady and periodic conditions near room-temperature. The results were compared to the Raman spectroscopy, which measures the local temperature at the cantilever tip

On the Role of Minor Galaxy Mergers in the Formation of Active Galactic Nuclei

The large scale (~ 100 kpc) environments of Seyfert galaxies are not significantly different from those of non-Seyfert galaxies. In the context of the interaction model of the formation of active galactic nuclei (AGN), it has been proposed that AGN form via "minor mergers" of large disk galaxies with smaller companions. We test this hypothesis by comparing the nuclear spectra of 105 bright nearby galaxies with measurements of their R or r band morphological asymmetries at three successive radii. We find no significant differences in these asymmetries between the 13 Seyfert galaxies in the sample and galaxies having other nuclear spectral types (absorption, H II-region like, LINER), nor is there strong qualitative evidence that such mergers have occured among any of the Seyferts or LINERs. Thus either any minor mergers began > 1 Gyr ago and are essentially complete, or they did not occur at all, and AGN form independently of any type of interaction. Support for the latter interpretation is provided by the growing evidence that supermassive black holes exist in the cores of most elliptical and early-type spiral galaxies, which in turn suggests that nuclear activity represents a normal phase in the evolution of the bulges of massive galaxies. Galaxy mergers may increase the luminosity of Seyfert nuclei to the level of QSOs, which could explain why the latter objects appear to be found in rich environments and in interacting systems.Comment: 13 pages, 2 figures, to appear in Astrophysical Journal Letter

A Geophysical Study of the Easternmost Piedmont: Brunswick County, Virginia

Gravity and magnetic models indicate that a steeply dipping, mylonitic shear zone recognized by reconnaissance mapping in the easternmost Piedmont of Brunswick County, Virginia is a listric fault. A pronounced 3 to 5 mgal Bouguer anomaly high is associated with the fault zone. A band of N10° trending aeromagnetic anomalies delineate the areal extent of the fault zone. The fault zone flattens eastward over a short distance to a depth of 15 kms where it joins a near horizontal surface that cuts across the region. This surface is herein interpreted to be a decollement. The fault zone of this study is interpreted to be a part of the Eastern Piedmont Fault System (EPFS) of Hatcher et al (1977). Listric geometry of this fault suggests it is a splay off the master decollement responsible for the Appalachian fold and thrust belt to the west. Inclusion of the fault of this study in the EPFS suggests the EPFS faults may also be listric