No description available.

No description available.

The objective of this study was to fully characterise drift phenomena in inductively coupled plasma atomic emission spectroscopy (ICP-AES) in order to develop novel correction procedures to aid routine analysis. Long-term drift of the analytical signal continues to be a potential disadvantage when using ICP-AES and often necessitates regular recalibration. The long-term stability of three commercially available Instruments was studied using In each case a range of analyte and intrinsic plasma emission lines. Long-term fluctuations were observed which generated drift bias of up to 20% on the initial values. The drift pafterns were characterised and found to be qualitatively reproducible. In most cases, similar long-term fluctuations were observed independent of the analyte or nature of the emission line. In addition, high inter-element correlation was observed on the long-term fluctuations even when sequential acquisition was employed. In order to study the fundamental causes of drift, the effect of two key instrumental parameters, i.e. the RF power and the nebutiser gas flow rate were studied with respect to the stability of the signal. Different drift patterns were found depending on the working conditions. Classical statistical methods and a multi-way approach. PARAFAC. were then employed to describe the system. The use of intemal standards to correct for drift has also been investigated, but found to be of benefit only under certain defined conditions (i.e. robust conditions, high RF power and low nebuliserflow rate). At soft conditions, low RF power and medium to high nebuliser flow rate, the system Is very unstable and intemal standardisation is not fully effective as a correction method. For such conditions, a novel correction procedure has been developed, which employs the drift pattem of one intrinsic plasma line (i.e. an argon line) and a correction factor which is specific for each emission line. The drift values were reduced from around 20% before correction to better than ±2% following the described protocol. Finally, the effects of chemical matrices on the long-term stability of the emission signals have been evaluated. Three synthetic matrices were prepared simulating nitric, soil and water matrices. The stability of the instrument when working wrth these matrices at both robust and soft conditions was found to be poor, especially when the solution was matched with the soil matrix. The use of more robust conditions did not improve the long-temi stability of the emission signals. The outcome of this study proved to be a better understanding of drift phenomena and a novel method for drift correction.

No description available.

The engineering problems in Geomechanics and Geotechnical fields are commonly treated through the infinite or semi-infinite media. The best approach to solve these problems numerically is by coupling a finite element or a finite difference with boundary element numerical methods. Coupling the bounded domain modelled by Flac3D, a well-known program that implements an explicit finite difference method, with the boundary element method, which satisfies exactly the governing Partial Differential Equations (PDE) in the surrounding infinite or semi-infinite medium, combines the capabilities and the advantages of both methods. The Domain Decomposition Method (DDM) partitions the task of solving the PDE into separate computations over the coupled sub-domains. This method allows the FDM (Flac3D program) and the Boundary Element Method (BEM) program to work independently and interactively. In contrast, at the level of discretized equations, the coupling method requires building a complicated unified system of equations. Therefore, a Domain Decomposition Sequential Dirichlet-Neumann Iterative Coupling Method is developed in this thesis to couple both programs. The method is applied in four cases, 2D and 3D infinite and semi-infinite domains, using the appropriate fundamental solutions in the Boundary Integral Equation required for each case. After applying this method, the mechanical responses computed by Flac3D is corrected and the same responses far from the bounded domain are computed with less computer runtime (CPU) compared with the uncoupled Flac3D solution. The method is also verified by comparing the obtained numerical results with the corresponding analytical solutions. Two BEM pre and post processing intrinsic plug-ins are created, which provide access to the data of Flac3D, as well as the internal structure of the programming language embedded within Flac3D program. These intrinsics are 10 to 100 times faster to execute than the functions created using the Flac3D embedded language. Furthermore, the complementary part of the Kernels is derived based on Mindlin's fundamental solutions. These Kernels are required to compute the stress inside the 3D semi-infinite domain.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 5 uppsatser.

Honors project (B.S.) -- Carson-Newman College, 2009. / Project advisor: Dr. Sean Cordry. Includes bibliographical references (p. 27).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on August 11, 2006). PDF text of dissertation: xiii, 168 p. : ill. ; 3.46Mb. UNI publication number: AAT 3208091. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.

L'objectif principal de ma thèse était de développer de nouvelles technologies et des outils pour l’étude de l’activation des récepteurs couplés aux protéines G (GPCR).À la surface de la cellule se trouve une multitude de récepteurs qui jouent un rôle critique dans la communication cellule-cellule, dont les GPCR, une famille de récepteur utilisant les protéines G intracellulaires pour transmettre leurs signaux. Le ciblage de ces récepteurs à des fins thérapeutique est innovant et très prometteur. Mais à ce jour seuls quelques médicaments ciblant les GPCR ont été mis sur le marché, en partie en raison d'un manque d'outils permettant le suivi de leur action sur les cellules natives.L’objectif de cette thèse est donc de développer des tests simples pour suivre l’activation de n’importe quel GPCR. Pour développer ce type de test, nous avons décidé d'utiliser des fragments d'anticorps appelés nanobodies. Les anticorps sont des protéines du sang produites en réponse à un antigène spécifique qui sont capable de le neutraliser. Les nanobodies correspondent au domaine variable de certains anticorps de camélidés. En raison de leur faible taille (13 kDa) et de leur site de liaison à l'antigène réduit, les nanobodies se lient souvent à des cavités et présentent une grande sensibilité aux changements de conformation de l'antigène. / The main objective of my thesis was to develop technologies and tools to study activation of G protein-coupled receptors (GPCRs).The cell surface is displaying a multitude of receptors, who play critical roles in cell-cell communication. Among them, GPCRs represent a large family relying on the use of intracellular G proteins for their signaling. Targeting these receptors for therapies is very promising and innovative. So far, only few new drugs have been put on the market, partly due to a lack of tools enabling the follow-up of their action on native cells.The aim of this thesis is thus to develop simple assays to study activation of any GPCRs. To develop this kind of test, we used antibody fragments called nanobodies. Antibodies are blood protein produced in response to and counteracting a specific antigen. Nanobodies correspond to antibody fragments derived from the variable domain of a special class of camelid antibodies. Because of their small size (13 kDa) and reduced antigen binding site, nanobodies often bind cavities and show a high sensitivity to antigen conformational changes.