Three essays on relationships between the public sector and population migration

This dissertation is a collection of papers examining the consequences and determinants of population migration at the state and county level. The first chapter introduces the importance of domestic migration in the United States and briefly presents the issues that are covered in this work. The second chapter focuses on the possibility that state outmigration could result in reduced support of public higher education. Some authors have hypothesized that forward-looking state legislators respond to outmigration of certain age groups by reducing appropriations to higher education. In the empirical model, outmigration is disaggregated into six age groups to examine varying effects of migration on public finances over the life-cycle. The third chapter shifts focus to consider environmental contamination as a determinant of county migration flows. While a number of location-specific amenities have been considered in the migration literature, a rigorous examination of the effects of environmental degradation is absent. The spatial autoregressive model is utilized to account for spatial dependence in the measurements of inmigration, outmigration, and net migration disaggregated by poverty status. The results show that toxic chemical releases reduce the rate of inmigration and net migration for the poor and nonpoor. Hazardous air pollutant emissions are then introduced to the model and are associated with a decreased rate of inmigration and outmigration for the poor and nonpoor. The fourth chapter is an extension of the third and considers the effects of air pollution and air quality on county migration flows. Substantial differences could exist between migrant responses to the measures of contamination in the third chapter and the air quality measures used in this chapter. Air pollution is strictly regulated and air quality information is widely available. The estimates show that increased air pollutant emissions reduce nonpoor inmigration, outmigration, and net migration and poor inmigration and outmigration. The effects of nonattainment designation for exceeding allowable ambient concentrations are more pronounced. The results are confirmed when alternate measures of emissions and air quality are employed. The fifth chapter concludes and discusses future extensions

Focused ion beam modification of atomic force microscopy tips for near-field scanning optical microscopy

This is the published version, also available here: http://dx.doi.org/10.1063/1.1430028.A probe for near-field scanning optical microscopy is demonstrated based on a high index glass sphere attached to the end of a conventional atomic force microscopy tip. The sphere is machined into a pyramid geometry using a focused ion beam(FIB) instrument, coated with aluminum to confine the excitation light, and milled further with the FIB to open an aperture at the end of the tip. Near-field fluorescence images of 50 nm fluorescent latex spheres reveal subdiffraction limit spatial resolution, illustrating the utility of these probes for near-field scanning optical microscopy

Contemporary climatic analogs for 540 North American urban areas in the late 21st century

It is challenging to communicate abstract future climate estimates. Here the authors utilized climate-analog mapping and they identified that North American urban areas’ climate by the 2080’s will become similar to the contemporary climate of locations hundreds of kilometers away and mainly to the south, while many urban areas will have no modern equivalent analogs under the RCP8.5 scenario

Observational manifestations of solar magneto-convection -- center-to-limb variation

We present the first center-to-limb G-band images synthesized from high resolution simulations of solar magneto-convection. Towards the limb the simulations show "hilly" granulation with dark bands on the far side, bright granulation walls and striated faculae, similar to observations. At disk center G-band bright points are flanked by dark lanes. The increased brightness in magnetic elements is due to their lower density compared with the surrounding intergranular medium. One thus sees deeper layers where the temperature is higher. At a given geometric height, the magnetic elements are cooler than the surrounding medium. In the G-band, the contrast is further increased by the destruction of CH in the low density magnetic elements. The optical depth unity surface is very corrugated. Bright granules have their continuum optical depth unity 80 km above the mean surface, the magnetic elements 200-300 km below. The horizontal temperature gradient is especially large next to flux concentrations. When viewed at an angle, the deep magnetic elements optical surface is hidden by the granules and the bright points are no longer visible, except where the "magnetic valleys" are aligned with the line of sight. Towards the limb, the low density in the strong magnetic elements causes unit line-of-sight optical depth to occur deeper in the granule walls behind than for rays not going through magnetic elements and variations in the field strength produce a striated appearance in the bright granule walls.Comment: To appear in ApJL. 6 pages 4 figure

Three-dimensional seismic structure of the Mid-Atlantic Ridge (35°N) : evidence for focused melt supply and lower crustal dike injection

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): B09101, doi:10.1029/2004JB003473.We gathered seismic refraction and wide-angle reflection data from several active source experiments that occurred along the Mid-Atlantic Ridge near 35°N and constructed three-dimensional anisotropic tomographic images of the crust and upper mantle velocity structure and crustal thickness. The tomographic images reveal anomalously thick crust (8–9 km) and a low-velocity “bull's-eye”, from 4 to 10 km depth, beneath the center of the ridge segment. The velocity anomaly is indicative of high temperatures and a small amount of melt (up to 5%) and likely represents the current magma plumbing system for melts ascending from the mantle. In addition, at the segment center, seismic anisotropy in the lower crust indicates that the crust is composed of partially molten dikes that are surrounded by regions of hot rock with little or no melt fraction. Our results indicate that mantle melts are focused at mantle depths to the segment center and that melt is delivered to the crust via dikes in the lower crust. Our results also indicate that the segment ends are colder, receive a reduced magma supply, and undergo significantly greater tectonic stretching than the segment center.This research was supported by U.S. National Science Foundation grants OCE-0203228 and OCE-0136793; support for V. Lekic was provided by the IRIS undergraduate internship program

Human indoor climate preferences approximate specific geographies

Root mean square error analysis (between indoor and outdoor climates) and results for temperature and vapor pressur