published_or_final_version / abstract / Dentistry / Doctoral / Doctor of Philosophy

For almost 50 years, researchers have been exploring the use of stereoscopic displays for visualizing and interacting with three-dimensional (3D) data. Unfortunately, a number of unfavorable qualitative properties have impeded the wide-spread adoption of traditional 3D displays. The volumetric display, a more recent class of 3D display to emerge, possesses unique features which potentially makes it more suitable for integration into workplace, classroom, and even home environments. In this dissertation we investigate volumetric displays as an interactive platform for 3D applications. We identify the inherent affordances unique to volumetric displays, such as their true 3D display volume, 360° viewing angle, and enclosing surface. Identifying these properties exposes human factor issues which we investigate and interaction issues which we address. First, we evaluate the user’s ability perceive imagery displayed by a volumetric display. In a formal experiment, we show that depth perception can be improved, in comparison to more traditional platforms. We then perform an experiment which evaluates users’ ability to read text under 3D rotations, and present a new algorithm which optimizes text rotation when viewed my multiple users. Next, we investigate the user’s ability to select 3D imagery within the display. Results show that the dimension defining the depth of the object can constrain user performance as much as or more than the other two dimensions of the target. This leads us to explore alternative methods of selection which are less constraining to the user. We define a suite of new selection techniques, of which several are found to have significant benefits in comparison to techniques traditionally used in 3D user interfaces. Next, we describe our development of the first working interactive application, where a volumetric display is the sole device for input and display. The application presents a first glance at what the equivalent of today’s graphical user interface might be on a volumetric display. We then develop a prototype application which allows multiple users to simultaneously interact with the volumetric display. We discuss and address the core issues related to providing such a collaborative user interface, and report feedback obtained from usage sessions and expert interviews.

For almost 50 years, researchers have been exploring the use of stereoscopic displays for visualizing and interacting with three-dimensional (3D) data. Unfortunately, a number of unfavorable qualitative properties have impeded the wide-spread adoption of traditional 3D displays. The volumetric display, a more recent class of 3D display to emerge, possesses unique features which potentially makes it more suitable for integration into workplace, classroom, and even home environments. In this dissertation we investigate volumetric displays as an interactive platform for 3D applications. We identify the inherent affordances unique to volumetric displays, such as their true 3D display volume, 360° viewing angle, and enclosing surface. Identifying these properties exposes human factor issues which we investigate and interaction issues which we address. First, we evaluate the user’s ability perceive imagery displayed by a volumetric display. In a formal experiment, we show that depth perception can be improved, in comparison to more traditional platforms. We then perform an experiment which evaluates users’ ability to read text under 3D rotations, and present a new algorithm which optimizes text rotation when viewed my multiple users. Next, we investigate the user’s ability to select 3D imagery within the display. Results show that the dimension defining the depth of the object can constrain user performance as much as or more than the other two dimensions of the target. This leads us to explore alternative methods of selection which are less constraining to the user. We define a suite of new selection techniques, of which several are found to have significant benefits in comparison to techniques traditionally used in 3D user interfaces. Next, we describe our development of the first working interactive application, where a volumetric display is the sole device for input and display. The application presents a first glance at what the equivalent of today’s graphical user interface might be on a volumetric display. We then develop a prototype application which allows multiple users to simultaneously interact with the volumetric display. We discuss and address the core issues related to providing such a collaborative user interface, and report feedback obtained from usage sessions and expert interviews.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 94-99). Available also in a digital version from Dissertation Abstracts.

This thesis is devoted to understanding solute-solvent interactions in folded and unfolded proteins. To this end, we have studied partial molar volume, Vo, and adiabatic compressibility, KoS, of 20 amino acid side chains using low weight molecular model compounds, N-acetyl amino acid amide and its derivatives, between 18 oC and 55 oC. We used our data to develop an additive scheme for calculating the partial specific volume and adiabatic compressibility of fully extended polypeptide chains as a function of pH and temperature. We compared our calculated volumetric characteristics of the fully extended conformations of apocytochrome c and apomyoglobin with the experimental values measured in neutral pH (for apocytochrome c) or acidic pH (for apomyoglobin). The comparison between the calculated and experimental volumetric characteristics suggested that neither apocytochrome c nor apomyoglobin are fully unfolded and retain solvent-inaccessible amino acid residues. To study cosolvent-solute interactions, we determined Vo and KoS of amino acid side chains and glycyl units as a function of urea concentration. We analyzed these data within the framework of a statistical thermodynamic formalism to determine the association constants, k, for the reaction in which urea binds to each of the amino acid side chains and the glycyl unit replacing two water molecules in solvation shell. Our determined k range from 0.04 to 0.39 M with the average of 0.16 ± 0.09 M. There was no apparent correlation between the values of k and the ratio of polar to nonpolar solvent accessible surface areas. This study supports a direct interaction model in which urea denatures a protein by concerted action via favorable interactions with a wide range of protein groups. In addition, we have presented buffer ionization effect on the volume of protein denaturation could be significant with the potential to affect not only its magnitude but also its sign using a pressure perturbation calorimetric technique. Our results identified buffer ionization as an important determinant of protein transition volume that needs to be carefully taken into account. Results described in this work provide fundamental understanding of solute-solvent interaction in both folded and unfolded proteins.

No description available.

This thesis is devoted to understanding solute-solvent interactions in folded and unfolded proteins. To this end, we have studied partial molar volume, Vo, and adiabatic compressibility, KoS, of 20 amino acid side chains using low weight molecular model compounds, N-acetyl amino acid amide and its derivatives, between 18 oC and 55 oC. We used our data to develop an additive scheme for calculating the partial specific volume and adiabatic compressibility of fully extended polypeptide chains as a function of pH and temperature. We compared our calculated volumetric characteristics of the fully extended conformations of apocytochrome c and apomyoglobin with the experimental values measured in neutral pH (for apocytochrome c) or acidic pH (for apomyoglobin). The comparison between the calculated and experimental volumetric characteristics suggested that neither apocytochrome c nor apomyoglobin are fully unfolded and retain solvent-inaccessible amino acid residues. To study cosolvent-solute interactions, we determined Vo and KoS of amino acid side chains and glycyl units as a function of urea concentration. We analyzed these data within the framework of a statistical thermodynamic formalism to determine the association constants, k, for the reaction in which urea binds to each of the amino acid side chains and the glycyl unit replacing two water molecules in solvation shell. Our determined k range from 0.04 to 0.39 M with the average of 0.16 ± 0.09 M. There was no apparent correlation between the values of k and the ratio of polar to nonpolar solvent accessible surface areas. This study supports a direct interaction model in which urea denatures a protein by concerted action via favorable interactions with a wide range of protein groups. In addition, we have presented buffer ionization effect on the volume of protein denaturation could be significant with the potential to affect not only its magnitude but also its sign using a pressure perturbation calorimetric technique. Our results identified buffer ionization as an important determinant of protein transition volume that needs to be carefully taken into account. Results described in this work provide fundamental understanding of solute-solvent interaction in both folded and unfolded proteins.

Summary of Thesis (Chemistry)--Vanderbilt. / "Private edition, distributed by the Joint University Libraries, Nashville, Tennessee." Includes bibliographical references (p. 7).

Thesis (Ph. D.)--Columbia University, 1932. / Vita. Bibliography: p. 31.

Summary of Thesis (Chemistry)--Vanderbilt. / "Private edition, distributed by the Joint University Libraries, Nashville, Tennessee." Includes bibliographical references (p. 7).