The permeable press experiment was performed for aqueous clay mineral systems to understand the relationship between the water film thickness and the applied permeable pressure. Water film thickness between particles was calculated from the particle size and the linear drying shrinkage of pressed bodies. The permeable press experimental results were compared to the calculated total interaction pressures between particles using the DLVO theory. The kaolinite and the metakaolinite had the same particle shape. Kaolinite particles were crystalline, and metakaolinite particles were short-range order. The kaolinite had the point of zero net charge, PZNC, at pH 5.7. However, the kaolinite showed multi-cross points at pHs 4.6, 5.7, 6.2, and 7.2. These multi-cross points were in agreement with the theoretical titration using the two-site surface complex reaction model by Carroll-Webb and Walther. On other hand, the metakaolinite had the PZNC at pH 7.2 as a common intersection point. If the zeta potential at pH(PZNC) is identical to the silica basal surface potential, the silica surface charge densities are calculated as - 2.6 μC cm⁻² for the kaolinite and - 2.7 μC cm⁻² for the metakaolinite, respectively. The calculated surface charge density is equivalent to one aluminum atom substituted in 54 silicon atoms in the silica tetrahedral layer. The total interaction pressures using the DLVO theory corresponded to the permeable press experimental results of the metakaolinite-0.1 M NaCI systems. The surface of the metakaolinite was estimated to have immobile water layers between 5 and 8 molecules thick. The metakaolinite samples cracked in experiments when the applied permeable pressure increased. This phenomenon can be explained by a vanishing capillary pressure: contacting immobile layers. The permeable press experimental results of all the kaolinite systems were significantly higher than the calculated total interaction pressures. The slope of the natural log of the permeable pressure and the water film thickness of the kaolinite systems indicated the existence of a longer-range repulsive pressure than that of the metakaolnite systems. The DLVO theory cannot explain the kaolinite systems because the nature of materials, such as an atomic configuration of the surface, which induces the structural forces, is not considered.

In this dissertation we study several improvements to algorithms used to generate comprehensive Groebner bases of Volker Weispfenning (7). Comprehensive Groebner bases are bases for ideals in the ring of polynomials in several variables whose coefficients are polynomials in several symbolic parameters over a given field. These bases have the fundamental property that, for any possible assignment (specialization) of the field elements for the parameters, the comprehensive Groebner basis generators become generators for a usual Groebner basis for the ideal of polynomials with coefficients in the field. Chapter 1 gives the necessary background for understanding the basic construction of comprehensive Groebner bases. We show how it is also possible to construct these bases for ideals in the ring of polynomials whose coefficients are rational functions of the symbolic parameters. We amplify the description of assigning "colors" to coefficients as given in (7). These assignments are used to establish criteria to determine the effect specialization will bear upon a given coefficient of a given polynomial. We also amplify the constructions for S-polynomial and normal form computations in this realm. In Chapter 2, we present several modifications to the algorithms in Chapter 1. These modifications allow for more efficient machine computations and yield simpler output. We show a new design methodology for assignments of "colors" that allows for more readable and useful output. We encode this methodology in our "saturated form" of a condition which makes good use of Groebner basis theory and saturations of ideals. This new design allows for sharper precision when working with comprehensive Groebner bases. In particular, we demonstrate how this design eliminates all unnecessary "virtual" Buchberger algorithms as described in (1). In Chapter 3, we show the precision of our new design in examples from several areas of commutative algebra. We demonstrate the simplicity that may be attained in examples from Automatic Geometric Theorem Proving, and in the study of parametric varieties. Also, we embed our new design in an algorithm that has potential use in the study of dimension bounds of parametric varieties.

Communities of granivorous desert rodents are structured by habitat selection and may be influenced by either predatory risk or resources. To examine these hypotheses, I manipulated illumination using lanterns, parachute canopies, or natural moonlight and resources using seeds. Foraging behavior is risk-sensitive; increased illumination reduces foraging in open areas while adding shadows to open areas using parachutes increases foraging there. Foraging behavior is also affected by resource enrichments. Differences among species in habitat selection were determined by specific abilities to detect and avoid predators. The least vulnerable species, Dipodomys deserti, foraged heavily in the open and was largely unaffected by treatments; other species of kangaroo rats and kangaroo mice also prefer the open, but responded to both risk and resource manipulations; highly vulnerable Peromyscus maniculatus was always restricted to bushes even under the most favorable circumstances; Perognathus longimembris was restricted to bushes in the absence of P. maniculatus in 1980 and was displaced from preferred microhabitats by the presence of kangaroo rats in 1981. A correlation between auditory bullar volume and use of open habitat by the various species in this community suggests that predatory risk provides an axis along which habitat segregation occurs. Predation can shape community structure by influencing foraging decisions of individuals. Desert rodents from North America and the Middle East have converged morphologically and perhaps in behavior and in community structure. Using desert rodent communities in the Great Basin Desert of U.S.A. and in the Negev Desert of Israel, I manipulated predatory risk in both communities and noted that foraging activity declines with increased predatory risk. Additional evidence suggests that predation also affects habitat selection behavior in both communities. Furthermore, differences in habitat utilization among species which promotes coexistence are related to morphological anti-predator specialization of the species. Predation appears to have shaped behavior and contributed to community structure in similar ways in both communities.