The Equity of Public Education Funding in Georgia, 1988-1996

A study of the effect of Quality Basic Education on the level of equity of public education funding in Georgia

Zero gravity crystal growth Final report

Experimental device for growing crystals under zero gravity condition

Research study on materials processing in space, experiment M512

Gallium arsenide, a commercially valuable semiconductor, has been prepared from the melt (M.P. 1237C), by vapor growth, and by growth from metallic solutions. It has been established that growth from metallic solution can produce material with high, and perhaps with the highest possible, chemical homogeneity and crystalline perfection. Growth of GaAs from metallic solution can be performed at relatively low temperatures (about 600C) and is relatively insensitive to temperature fluctuations. However, this type of crystal growth is subject to the decided disadvantage that density induced convection currents may produce variations in rates of growth at a growing surface. This problem would be minimized under reduced gravity conditions

Energetic Impacts of Passage Delays in Migrating Adult Atlantic Salmon

For any migratory organism, habitat connectivity is critical for population stability. Structures that impede movement between necessary habitats can be damaging to population persistence. In riverine systems, dams act as migratory barriers, altering ecosystems and delaying, injuring, or otherwise impairing migratory fish movement into essential habitat. Critically endangered Atlantic salmon (Salmo salar) populations in Maine have been on the decline since the 1800s. Because most Atlantic salmon rivers are now highly dammed systems, hydropower dams have been cited as causal to the decline in returning adult populations. Previous studies have demonstrated that Atlantic salmon experience substantial delays below dams while moving upstream, but current state of knowledge with respect to metabolic costs and fitness outcomes for delayed Atlantic salmon provides no clear quantification of risk associated with this delay. I sought to understand consequences of delay in the context of an increased thermal experience below dams. With my collaborators, I have documented that water temperatures below surface-release dams remain several degrees warmer throughout peak summer months than water temperatures in upstream sections of river. Thus, adult Atlantic salmon experiencing delays below dams will be subject to warmer thermal experiences than if they had moved rapidly to upstream sections of river. As ectotherms, ambient water temperatures directly impact physiological processes, but salmonids generally have a narrow optimum temperature range. As waters warm to outside that range, metabolic processes become more energetically costly. That excess energy use might manifest itself in reduced individual reproductive success, or in the case of Atlantic salmon, a decrease in population iteroparity rates. In Chapter 1, we quantified the energetic cost of dam-mediated delays of adult migrating Atlantic salmon using HOBO temperature loggers, temperature-logging radio tags, and a Distell Fish Fatmeter as a noninvasive surrogate for full-body energy estimation. On the Penobscot River and Kennebec Rivers of central Maine, we tagged fish, released them a short distance below the dams, and tracked their movements back upstream, taking a Fatmeter measurement first at tagging and then after ascending the fish way at the respective dams. We found that Atlantic salmon experienced delays of two to three weeks on average while attempting to pass dams on their respective rivers. I that time, these fish lost between 11.1 and 19.4% of their starting endogenous fat reserves. Using the temperature-logging radio tags, we documented the individual thermal experience of each study salmon and determined that the thermal experience did indeed predict fat loss. Our results suggest that dams cause delays, not only extending migration times but also exposing adult Atlantic salmon to warmer water temperatures, compounding energetic impacts of dams and depleting available energy reserves. In Chapter 2, we utilized a bioenergetic model to further understand energy allocation of migrating adult Atlantic salmon in the context of delays at dams and corresponding water temperatures. Atlantic salmon can survive after spawning to be iteroparous, engaging in multiple reproductive life cycles over the course of a lifetime. Iteroparity is thought to be important to the conservation of this federally endangered species through greater population recruitment but currently, repeat spawners in Maine populations have been nearly eliminated. We modeled five different Atlantic salmon spawning runs in five different hypothetical rivers with either zero, one, two, three, or four dams presenting as migration barriers causing delays and subjecting salmon to warmer water temperatures. The results of our model showed that as the number of dams on a river increased, the number of post-spawn surviving Atlantic salmon decreased. On the unimpeded river, 6.3% of the run survived after spawning but on a river with four dams, only 2.8% of the returning salmon run survived. We also found that the number of salmon able to complete the single reproductive event decreased and the number of salmon that died before spawning increased as dams were added to the modeled system. Our results from Chapter 2 suggest that rapid movement through warmer downstream sections of rivers to upstream, cooler waters is key to increasing iteroparity rates in spawning populations and overall reproductive success

High-strength tungsten alloy with improved ductility

Alloy combines superior strength at elevated temperatures with improved ductility at lower temperatures relative to unalloyed tungsten. Composed of tungsten, rhenium, hafnium, and carbon, the alloy is prepared by consumable electrode vacuum arc-melting and can be fabricated into rod, plate, and sheet

HST Observations of the Central-Cusp Globular Cluster NGC 6752. The Effect of Binary Stars on the Luminosity Function in the Core

We consider the effect of binary stars on the main-sequence luminosity functions observed in the core of globular clusters, with specific reference to NGC 6752. We find that mass segregation results in an increased binary fraction at fainter magnitudes along the main-sequence. If this effect is not taken into account when analyzing luminosity functions, erroneous conclusions can be drawn regarding the distribution of single stars, and the dynamical state of the cluster. In the core of NGC 6752, our HST data reveal a flat luminosity function, in agreement with previous results. However, when we correct for the increasing binary fraction at faint magnitudes, the LF begins to fall immediately below the turn-off. This effect appears to be confined to the inner core radius of the cluster.Comment: 10 pages, 3 figures Accepted to ApJ Lett Vol 513 Number

The Socially Constructive Aspects of Outside Agents in Community Decision-Making in a Rural Area

The outside-change agent is dangerous, something to be feared (based on past experiences, long since blurred by boredom and powerlessness) and not taken into the community. The outsider offers few, if any, tangible immediately useable resources -- only promises and fancy talk. Limited experience has taught the Appalachian that promises fade into misery and fancy talk to poverty. The self-fulfilling prophesy of inhospitality and disbelief in oneself, turn the Appalachian against the change agent and challenge the agent to leave the area out of self-felt persistent futility

Finite-Temperature Auxiliary-Field Quantum Monte Carlo for Bose-Fermi Mixtures

We present a quantum Monte Carlo (QMC) technique for calculating the exact finite-temperature properties of Bose-Fermi mixtures. The Bose-Fermi Auxiliary-Field Quantum Monte Carlo (BF-AFQMC) algorithm combines two methods, a finite-temperature AFQMC algorithm for bosons and a variant of the standard AFQMC algorithm for fermions, into one algorithm for mixtures. We demonstrate the accuracy of our method by comparing its results for the Bose-Hubbard and Bose-Fermi-Hubbard models against those produced using exact diagonalization for small systems. Comparisons are also made with mean-field theory and the worm algorithm for larger systems. As is the case with most fermion Hamiltonians, a sign or phase problem is present in BF-AFQMC. We discuss the nature of these problems in this framework and describe how they can be controlled with well-studied approximations to expand BF-AFQMC's reach. The new algorithm can serve as an essential tool for answering many unresolved questions about many-body physics in mixed Bose-Fermi systems.Comment: 19 pages, 6 figure

Group Size and Social Conflict in Complex Societies

Conflicts of interest over resources or reproduction among individuals in a social group have long been considered to result in automatic and universal costs to group living. However, exploring how social conflict varies with group size has produced mixed empirical results. Here we develop a model that generates alternative predictions for how social conflict should vary with group size depending on the type of benefits gained from being in a social group. We show that a positive relationship between social conflict and group size is favored when groups form primarily for the benefits of sociality but not when groups form mainly for accessing group-defended resources. Thus, increased social conflict in animal societies should not be viewed as an automatic cost of larger social groups. Instead, studying the relationship between social conflict and the types of grouping benefits will be crucial for understanding the evolution of complex societies