Thesis. 1977. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Blank leaf bound in after leaf 5; no leaf 148. / Includes bibliographical references. / M.Arch.A.S.

Nanoscale structural characterization is critical to understanding the physical underpinnings of properties and behavior in materials with technological applications. The work herein shows how the pair distribution function technique can be applied to x-ray total scattering data for material systems which weakly scatter x-rays, a typically difficult task due to the poor signal-to-noise obtained from the structures of interest. Characterization and structural modeling are demonstrated for a variety of molecular and porous systems, along with the detection and characterization of disordered, minority phases and components. In particular, reliable detection and quantitative analysis are demonstrated for nanocrystals of an active pharmaceutical ingredient suspended in dilute solution down to a concentration of 0.25 wt. %, giving a practical limit of detection for ordered nanoscale phases within a disordered matrix. Further work shows that minority nanocrystalline phases can be detected, fingerprinted, and modeled for mixed crystalline and amorphous systems of small molecules and polymers. The crystallization of amorphous lactose is followed under accelerated aging conditions. Melt quenching is shown to produce a different local structure than spray drying or freeze drying, along with increased resistance to crystallization. The initial phases which form in the spray dried formulation are identified as a mixture of polymorphs different from the final α-lactose monohydrate form. Hard domain formation in thermoplastic polyurethanes is also characterized as a function of methylene diphenyl diisocyanate and butanediol component ratio, showing that distinct and different hard phase structures can form and are solved by indexing with structures derived from molecular dynamics relaxation. In both cases, phase fractions can be quantified in the mixed crystalline and amorphous systems by fitting with both standards or structure models. Later chapters, demonstrate pair distribution characterization of particle incorporation, structure, and synthesis of nanoporous materials. Nanoparticle size distributions are extracted from platinum nanoparticles nucleating within a zeolite matrix through structural modeling, and validated by transmission electron microscope studies. The structure of zirconium phosphonate-phosphate unconventional metal organic framework is determined to consist of turbostratically disordered nanocrystalline layers of Zr-phenylphosphonate, and the local environment of terbium intercalated between the layers is found to resemble the local environment in scheelite-type terbium phosphate. Finally, the early stages of reaction between aqueous zinc dinitrate hexahydrate and methanolic 2-methylimidazole are characterized using in situ total scattering measurements, showing that secondary building units of tetrahedrally coordinated by 2-methylimidazole initially form upon reaction. Overall, the methodologies are developed and applied toward phase detection, identification, solution, and behavior in pharmaceuticals, polymers, and nanoporous materials along with advice for carrying out experiments and analysis on such materials such that they can be extended to other similar systems.

by Zang Rui. / "Nov 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 78-82) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

All mC5-MTases are monomeric enzymes, except M. EcoHK31I and M. AquI which are MTases composed of two poly peptides. M.EcoHK31I is a mC5-MTase which recognizes the sequence 5-YGGCCR-3' and consists of polypeptide alpha and beta, with the latter gene encoded in an alternative reading frame of the former. All of the conserved motifs in mC5-MTases can be found in polypeptide alpha, except motif IX, which is located in polypeptide beta. Both polypeptides are required for in vitro methylation. / Methylation of cytosine residues in DNA occurs in diverse organisms from bacteria to humans. In higher eukaryotic organisms cytosine-C5 methyltransferase (mC5-MTase) is the only type of DNA MTase and it plays an important role in controlling a number of cellular processes including transcription genomic imprinting and DNA repair. In bacteria, there are three types of MTases, mC4-, mC5- and mAb-, classified according to the methylation site of the DNA. MTase and its cognate restriction endonuclease (ENase) form restriction-modification system. The role of MTase is to protect the host from its own ENase digestion while the ENase acts to degrade the invasion of foreign DNA. Sequence comparison of nearly 50 bacterial mC5-MTases has shown that these enzymes share an overall common protein architecture. Ten conserved motifs (I to X), each 10 to 20 amino acids in length, have been identified, five of which are highly conserved (I, IV, VI, VIII and X). In addition, all of these enzymes have a hypervariable region lying between motifs VIII and IX. It is called the target recognition domain (TRD), and is responsible for the specificity of DNA recognition and the choice of base to be methylated. / Since both of the polypeptides alpha and beta of M.EcoHK31I are sequenced and cloned into the expression vector separately, the role of DNA recognition and subunits interaction of individual polypeptides can be studied. By electromobility shift assay, we found that polypeptides alpha and beta complex recognize specific double strand oligos substrate. Polypeptide alpha-DNA formed aggregates and polypeptide beta alone did not bind DNA. Therefore, polypeptide beta assists the proper binding of polypeptide alpha to DNA substrate. Complex of polypeptide alpha and a polypeptide beta variant with N-terminal deletion of 41 amino acids showed a 16-fold reduction in methylation activity. Further deletion resulted in an inactive MTase. By surface plasmon resonance assay, the dissociation equilibrium constant (KD) of polypeptides alpha and beta complex was found to be 56.2nM and the KD for polypeptide alpha and DeltaN46-polypeptide beta complex was increased by about 95 folds, contributing by a drastic decrease in dissociate rate constant (kd) and an increase in association rate constant (ka). This indicated that the N-terminal region of polypeptide beta takes part in subunit interaction. / To pinpoint which amino acid residues located at the variable region of polypeptide alpha are important for DNA binding and subunits interaction, "charge-to-alanine scanning mutagenesis" were performed on 16 charge residues between Asp213 and Glu271 in the small domain. It was found that the five charge residues upstream of motif X are not required for activity. For other residues except K225, E240 and D245, the protein is active when the same charge is maintained. / Fung Wai To. / "March 2006." / Adviser: P. C. Shaw. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6376. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 180-201). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Após um levantamento inicial com 24 sujeitos, em uma instituição, foram observadas as ocorrências das auto-agressões de uma criança profundamente retardada, em diferentes situações do dia-­a-dia na instituição. Outras respostas da mesma criança foram também observadas e relacionadas com as auto-agressões. Dois grupamentos de ações foram identificados. Morder-se, juntamente com outras ações, aumentava diante de exigências de desempenho e restrição à locomoção; diminuía na presença de um pianinho ou quando havia música tocando. Bater-se na cabeça, juntamente com outras ações, pareceu ser controlado por estimulação auditiva. O conceito de auto-agressão foi discutido, sugerindo-se que comportamentos auto-lesivos (termo proposto, mais descritivo) poderiam ser auto-estimulatórios ou modalidades de agressão. Concluiu-se que o entendimento dos determinantes de comportamentos auto-lesivos pode dar-se através de sua análise funcional, feita em situação natural, pela análise de múltiplas respostas em múltiplas situações. Tal estudo pode trazer implicações para a elaboração de intervenções que promovam ganho significativos, múltiplos e permanentes. / A review of the existing literature showed a variety of self-aggressive acts*, which relate to other actions of the same individual. The same review showed furthermore that there are many situations in which such acts occur, with no agreement as to what originates and maintains self-aggression. After an initial survey in an institution including 24 subjects, the occurrence of self-aggressive acts was observed in a profoundly retarded child in different day-to-day situations at the institution. Other responses of the same child were also observed and related to the self-aggressive episodes. Most of the actions observed can be grouped into two classes of response. Biting herself and other related act ions increased in frequency when requirements were made and locomotion restricted, and decreased when a small piano was given to her or when music was playing. Hitting on the head and other related actions were seemingly controlled by auditory stimulation. The concept of self-aggression was discussed and self-injurious behavior (a more descriptive proposed expression) presented as either self-stimulation or a modality of aggression. It was concluded that an understanding of the determinants of self-injurious behavior can be achieved through functional analysis under natural conditions, including multiple responses in multiple situations. Such a study may have an impact on the development of measures that may lead to significant, multiple and permanent gains. * Self-injurious behavior is referred to, \"self-aggressive\" behavior.

Chifan, Kida, and myself introduced a new class of non-amenable groups denoted by ${\bf NC} \cap {\bf Quot}(\mathcal C_{rss})$ which gives rise to \emph{prime} von Neumann algebras. This means that for every $\G\in {\bf NC} \cap {\bf Quot}(\mathcal C_{rss})$ its group von Neumann algebra $L(\G)$ cannot be decomposed as a tensor product of diffuse von Neumann algebras. The class ${\bf NC} \cap {\bf Quot}(\mathcal C_{rss})$ is fairly large as it contains many natural examples of groups, some intensively studied in various areas of mathematics: all infinite central quotients of pure surface braid groups; all mapping class groups of (punctured) surfaces of genus $0,1,2$; most Torelli groups and Johnson kernels of (punctured) surfaces of genus $0,1,2$; and, all groups hyperbolic relative to finite families of residually finite, exact, infinite, proper subgroups. In a separate investigation, de Santiago and myself were able to extend the previous techniques that allowed us to eliminate the usage of the {\bf NC} condition and ultimately classify all the possible tensor factorization of the von Neumann algebras of groups that belong solely to ${\bf Quot}(\mathcal C_{rss})$. This provides a far-reaching generalization of the aforementioned primeness results; for instance, we were able to show that if $\Gamma$ is a poly-hyperbolic group, then whenever we have a tensor decomposition $L(\G)\cong P_1\bar\otimes P_2 \bar \otimes \cdots \bar\otimes P_n$ then there exists a product decomposition $\G\cong \G_1\times \G_2 \times \cdots \times \G_n$ with $\G_i \in {\bf Quot}(\mathcal C_{rss})$ and, up to amplifications, we have $L(\G_i)\cong P_i$ for all $i=1,n$.

This dissertation explores aspects of the representation theory for tensor algebras, which are non-selfadjoint operator algebras Muhly and Solel introduced in 1998, by developing a cohomology theory for completely bounded Hilbert modules. Similar theories have been developed for Banach modules by Johnson in 1970, for operator modules by Paulsen in 1997, and for Hilbert modules over the disc algebra by Carlson and Clark in 1995. The framework presented here was motivated by a desire to further understand the completely bounded representation theory for tensor algebras on Hilbert spaces. The focal point of this thesis is the first Ext group, Ext1, which is defined as equivalence classes of short exact sequences of completely bounded Hilbert modules. Alternate descriptions of this group are presented. For general operator algebras, Ext1 can be realized as the collection completely bounded derivations equivalent up to an inner derivation. When the operator algebra is a tensor algebra, Ext1 can be described as a quotient space of intertwining operators, a description analogous to a result of Ferguson in 1996 in the case of the classical disc algebra. A theorem of Sz.-Nagy and Foias from 1967, concerning contractions in triangular form, is applied to analyze derivations that are off-diagonal corners of completely contractive representations. It is proved that, in some cases, this analysis determines when all derivations must be inner or suggests ways to construct non-inner derivations. In the third chapter, a characterization is given of completely bounded representations of a tensor algebra in terms of similarities of contractive intertwiners. Also proven is that for a Csup*;-correspondence X over a Csup*;-algebra A and the Toeplitz algebra T(X), Mn(T(X))= T(Mn(X)). The analogous statement for tensor algebras is deduced as a corollary. In the final chapter, a brief survey of non-abelian category theory is provided. Extensions of completely bounded Hilbert modules over operator algebras are defined. Theorems asserting the projectivity of isometric modules and injectivity of coisometric modules by Carlson, Clark, Foias, and Williams in 1995 are generalized to the noncommutative setting of tensor algebras using commutant lifting. A result of Popesecu in 1996 for noncommutative disc algebras is also covered in the general framework of this thesis.

Integral equations form an important subject with applied mathematics due to their occurence in a variety of models of physical problems. The intent of this thesis is to present in a simple and concise manner the theory of integral equations in the context of their solution. A survey of the types of methods used for the approximation of linear integral equations is made along with the types of equations to which they may be applied. Detailed examples are presented for each of the methods discussed and wherever feasible, computer methods are employed.Ball State UniversityMuncie, IN 47306

Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by J. Stevenson Kenney. / Vita. Includes bibliographical references (leaves 157-165).

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.