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This thesis considers several instances of abstraction that arose in the design and implementation of the web programming language Links. The first concerns user interfaces, specified using HTML forms. We wish to construct forms from existing form fragments without introducing dependencies on the implementation details of those fragments. Surprisingly, many existing web systems do not support this simple scenario. We present a library which captures the essence of form abstraction, and extend it with more practical facilities, such as validation of the HTML a program produces and of the input a user submits. An important part of our library is a simple semantics, given as the composition of three primitive “idioms”, an interface to computation introduced by McBride and Paterson. In order to justify this approach we present a comparison of idioms with the related notions of monads and arrows, refining the informal claims in the literature. Our library forms part of the Links framework for stateless web interactions. We describe a related aspect of this system, a preprocessor that derives generic instances of functions, which we use to serialise server state between client requests. The abstraction in this case involves the shape of datatypes: the serialisation operation is specified independently of the particular types involved. Our final instance of abstraction involves abstract types. Functional programming languages typically offer one of two styles of abstract type: the abstraction boundary may be drawn using a private data constructor, or using a type signature. We show that there is a pair of semantics-preserving translations between these two styles. In the light of this, we revisit the decision of the Haskell designers to offer the constructor style, and define a library that supports signature-style definitions in Haskell by translation into the constructor style.

For zero-sum games, we have efficient solution techniques. Unfortunately, there are interesting games that are too large to solve. Here, a popular approach is to solve an abstract game that models the original game. We assume that more accurate the abstract games result in stronger strategies. There is substantial evidence to support this assumption. We begin by formalizing abstraction and refinement, a notion of expressive power for abstractions. We then show the assumption fails to hold under two criteria. The first is exploitability, which measures performance in the worst-case. The second is called the domination value, which measures how many mistakes a strategy makes. Despite these pathologies, we notice that larger strategies tend to make fewer mistakes and perform better in tournaments. Finally, we introduce strategy grafting, a technique that uses sub-game decomposition, which allow us to create good strategies in much larger spaces than previously possible.

The crux of this investigation is the combination of realist and abstract elements in pictorial space and negotiating the various pictorial problems this sets in motion. The interaction between these elements, especially in a spatial sense, creates both a visual and conceptual ambiguity central to the meaning of the work. Multiple treatments of painted form -- realist, expressive and abstract are interleaved producing divergent visual sensations. The transition from one visual sensation to another, the way the eye traverses believable forms to suddenly collide with the canvas, forced there by raw, painted gesture, is an unpredictable journey invoking visual perplexity, thereby alerting the viewer to potential meanings; the research paintings are not just images of things, they are images of things that would not normally exist together, but do so to create a story. It is intended that the viewer be directed toward the subject of the painting as much as the qualities of the medium itself. Influences as diverse as art historical painting, photography, the motion and lighting effects of film, the qualities of surface reflections and chiaroscuro, have been sourced to facilitate a new body of work. Directing the relationship of the viewer to the paintings through format and scale, (generally life size or very small) promotes a similar kind of interaction (the need to get up close and far away) to that of the application of pictorial space. This is an important aspect of the research; the optical process of focussing in and out is a microcosm of looking at the paintings installed in physical space. The subject of the paintings is female sexuality and its connection to identity, relationships and self-expression. It is also the conceptual object of 'Multiplicity', a principal idea in the work, ambiguous pictorial situations suggesting reality is not one thing but a combination of remembered, existing and subconscious experience. In the research, this concept also pertains to the painter (using memory, experience and imagination) and the audience viewing the work at different times.

Doctor of Philisophy (PhD) / Despite their early discovery, relatively few classes of ruthenium dinitrogen complexes are known. This work describes the successful coordination of dinitrogen to the electron-rich alkylphosphine cores [RuCl(dmpe)2]+ and [RuCl(depe)2]+ by chloride abstraction from both the cis and trans dichloro derivatives. One such complex, trans-[RuCl(N2)(dmpe)2](BArF24), possesses the most activated ruthenium νNN reported to date. A variety of chloride abstraction agents were tested on the cis and trans isomers of [RuCl2(P-P)2] (P-P = dmpe, depe) with the choice of abstracting agent, anion and solvent all found to significantly affect the outcome. Reaction with silver triflate and trimethylsilyl triflate was found to give dichlororuthenium(III) products, which could be readily reduced to the ruthenium(II) starting materials with common reducing agents, as well as by alcohols and hydrazine. The use of thallium triflate avoided oxidation and led to the formation of the crystallographically characterised polymeric incorporation product, [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] from trans-[RuCl2(dmpe)2] and the interesting chloride-bridged ruthenium dimer cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 from trans-[RuCl2(depe)2]. Anion exchange of the complex [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] with the non-coordinating anion tetrakis(3,5-bis(trifluoromethyl)phenyl)borate resulted in removal of thallium from the system and coordination of dinitrogen to give trans-[RuCl(N2)(dmpe)2](BArF24). Cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 was found to readily react with a variety of small ligands and gave products such as cis-[RuCl(CO)(depe)2](OTf), cis-[RuCl(NCMe)(depe)2](OTf), cis-[RuCl(CNtBu)(depe)2](OTf), cis-[RuCl(NH3)(depe)2](OTf), cis-[RuCl(N3)(depe)2], and trans-[RuCl(η2-H2)(depe)2](OTf). A preliminary X-ray single crystal structure analysis was conducted on the complex cis-[RuCl(CNtBu)(depe)2](OTf). The thallium(I) salt Tl(BArF24) was found to be an efficient chloride abstraction agent under mild conditions. Reactions with cis- and trans-[RuCl2(depe)2] and cis-[RuCl2(dmpe)2] furnished dinitrogen complexes of the form cis-[{RuCl(P-P)2}2(μ-N2)](BArF24)2, whilst reaction of trans-[RuCl2(dmpe)2] with Tl(BArF24) led to the stable five-coordinate complex trans-[RuCl(dmpe)2](BArF24). Vapour diffusion techniques applied to a solution of cis-[{RuCl(depe)2}2(μ-N2)](BArF24)2 gave rise to crystals of trans-[RuCl(N2)(depe)2](BArF24), on which preliminary X-ray molecular structure analysis was performed. Reactions of both cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 and trans-[RuCl2(dmpe)2] with high pressure (140 psi) dinitrogen at 140 150°C in methanol or tetrahydrofuran resulted in solvent carbonyl abstraction to afford trans-[RuCl(CO)(depe)2](OTf) and trans-[RuCl(CO)(dmpe)2](Cl) from the depe and dmpe complexes respectively. The molecular structure of trans-[RuCl(CO)(dmpe)2](Cl) was determined via single crystal X-ray structure analysis.

Thesis (Ph.D.)--Tufts University, 2002. / Adviser: Emily W. Bushnell. Submitted to the Dept. of Psychology. Includes bibliographical references (leaves 65-70). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (M.S.)--Ohio University, March, 1994. / Title from PDF t.p.

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 100-109).

Water resource management operations have significantly modified river flow regimes globally, prompting widespread lotic ecosystem responses. There is a growing need to better understand how increasingly prevalent hydrological alterations to riverine systems will affect biota dependent on specific elements of river flow regimes. This thesis examines macroinvertebrate community responses to river flow regimes modified by various water resource management operations across southwest England though four detailed investigations. The first study examines the influence of river impoundments and how macroinvertebrate communities differ between regulated and non-regulated sections of river. Findings from this investigation highlight that flow regulation alters the structure and function of faunal assemblages due to significant changes to the flow regime, rather than stream temperature modifications associated with the reservoirs. The second study focusses on groundwater dominated headwater streams transitioning from temporary (i.e. reaches periodically drying positioned furthest upstream) to perennial flow conditions which are subjected to variable groundwater abstraction intensities. The results indicate that macroinvertebrate communities respond significantly to the duration of antecedent flowing conditions and the spatial proximity of sampling sites to perennial sources; but faunal assemblages are not sensitive to groundwater abstraction. The third study examines how communities inhabiting different organic and mineralogical lotic habitats responded to multiple river flow properties (hydrological indices, anthropogenic flow alteration measures and hydraulic variables) in perennial, groundwater dominated systems. The findings highlight that faunal assemblages are most responsive to local hydraulic conditions measured at the point of sampling, rather than antecedent hydrological conditions. The influence of hydraulic properties on communities differs between lotic habitats, highlighting that mineralogical and organic characteristics of riverbeds strongly mediate how biota respond to flow. The final study presents the results of a long-term (1995-2016), region-wide (spanning Dorset, Hampshire and Wiltshire) examination of macroinvertebrate communities inhabiting groundwater dominated rivers and their responses to hydrological variability (including extreme low- and high-flow events) and anthropogenic flow alterations. The results indicate that indices characterising the proportion of discharge added to (through effluent water returns and low-flow alleviation strategies) or removed from the river (via groundwater abstraction) exert profound effects on faunal assemblages over long-term periods. These results provide empirical evidence that reductions in river discharges via groundwater abstraction of approximately 15% have no perceptible negative ecological effects on macroinvertebrate communities. The results from the four detailed investigations are used to develop conceptual models to illustrate how research undertaken within this thesis can be applied more widely. The findings and study designs presented within this thesis could inform surface and groundwater water resource management operations and underpin the development of environmental flow methodologies required to conserve riverine ecosystems globally.

Dynamic invariant detection is a software analysis technique that uses traces of function entry and exit from executing programs and infers partial specifications that characterize the observed behavior. The specifications are reported as logical precondition and postcondition expressions (invariants) that relate arguments, instance variables, and results. Detectors typically generate large collections of invariants, among which most are true but few are interesting or useful. Refining this flood of invariants into a useful subset often requires manual tuning through configuration options and modification of the program under analysis. Our research asks whether we can improve dynamic invariant detection by enabling explicit abstractions to be declared and applied to a program under analysis and whether this is practical; this dissertation shows that it is indeed practical and useful. Given a concrete program we can synthesize a model program composed of functions and modules that are abstractions of selected concrete modules. When we execute the model program in parallel with its underlying concrete program and apply dynamic invariant detection, we obtain abstracted invariants that can reveal the behavior of the underlying concrete program. We developed the Alembic system to support and experiment with the above technique, enabling a practical method for steering the invariant detection process and shaping the analysis to produce more refined results than obtainable via traditional means. Alembic provides a simple language for defining abstractions and managing detection experiments; the system generates the necessary instrumentation, representation classes, and functions, freeing the analyst to focus on the expression of abstractions and detection experiments. Alembic currently leverages the invariant detection capability of Daikon, a powerful first-generation detector, to analyze synthetic traces on abstractions. However, the principles we demonstrate apply to any detector and language that observes function entry and exit. We present some applications of this technique to example problems and then evaluate Alembic on production code such as the Guava class library. Our research suggests new uses for existing detectors and enables the design and evaluation of features to inform the next generation of dynamic invariant detection systems. This dissertation includes previously unpublished co-authored material.