A brief explanation of RNA and its general structure on dierent levels is given. The standard continuous Frenet frame is explained. A discrete version of the Frenet frame is explained in detail and constructed for a piecewise linear curve. The results of the application of the discrete Frenet frame to RNA is shown in the form of several distributions. An analysis of these distributions is conducted and gives some results regarding tiny structures in RNA. / <p>Master Degree Project thesis</p>

Optical nephelometry is the measurement of the angular distribution of light scattered from a particle suspension. Experimental nephelometers confirm the predictions of optical models and their readings are inverted to determine properties of unknown suspensions. Single scattering models, which assume a single particle interaction prior to detection, are used to model tenuous suspensions in the nephelometer. Multiple scattering models can be used to obtain higher-order solutions, but lack generality. Any given method addresses some subset of possible problems, e.g. tenuous or dense suspensions, small or large particles. This thesis explores the feasibility of using empirical models to extrapolate the single scattering approach in a non-linear manner, improving the generality of a multiple-scattering description. Initially, single scattering (Mie) theory for spherical particles is presented and extended to polydispersions of particles and to spectral scattering. The principle of integrating the single scattering result over a finite scattering volume is examined as a precursor to modelling the actual nephelometer. A low-cost, PC controlled scanning nephelometer is developed with a 0.9° resolution and ±150° range and a small (-25ml) volume sample cell. The photodiode detector has a numerical aperture of 0.079, providing, for most angles, a scattering volume with length 10mm and cross-section determined by the HeNe laser source ('-1mrn 2). The optics of the air/glass/water interfaces and of single and first-order multiple scattering over the scattering volume are modelled. These models are found to predict the scattering footprints observed in tenuous suspensions of spherical latex particles. Experimental data are obtained from tenuous to relatively dense (5% by volume) suspensions of latex spheres over a size range of 54nm to 14tm. These data are compared with single and first-order multiple scattering and their form and dependencies are considered. They are used to train an empirical neural (multi-layer perceptron) model of the multiple scattering based on particle characteristics and on the scattering footprint of the individual particles. This non-linear extrapolation of the single scattering model is applied to the nephelometer, improving the generality over a purely theoretical multiple scattering approach. The trained neural model is used, initially, to investigate some of the empirical characteristics of the multiple scattering process.

No description available.

Thesis (M.S.)--University of California, Berkeley, 1960. / "Criticality Studies, UC-46" -t.p. "TID-4500 (15th Ed.)" -t.p. Includes bibliographical references (p. 48-49).

Thesis--University of California, Berkeley, 1961. / "UC-4 Chemistry General" -t.p. "TID-4500 (16th Ed.)" -t.p. Includes bibliographical references (p. 106-111).

Thesis-University of Californa, Berkeley, July 1958. / Bibliography references : p. 59-60.

Thesis--University of California, Berkeley, 1959. / "Physics and Mathematics" -t.p. Includes bibliographical references (p. 89).

Thesis (Ph. D.)--Leiden Rijksuniversiteit, 1971. / Vita. Summaries in English and Dutch. Includes bibliographical references.

The electronic structure and photofragmentation dynamics of several molecular and cluster anions have been investigated in the gas phase via negative ion velocity-map imaging photoelectron spectrometer combined with tandem time-of-flight (TOF) mass spectrometry. Among others, photoelectron imaging investigation of the halogen- and cyano- substituted methyl radicals and corresponding carbenes has been performed on several mono- and hetero- substituted species – dicyanomethyl and chlorocyanomethyl radicals, ·CH(CN)₂ and ·CHClCN, and corresponding carbenes, NCCCN and CClCN. The results are discussed in comparison with the corresponding dichloro- species, focusing on the divergent effects of the halogen and pseudohalogen (CN) substitutions. A cooperative (captodative) interaction of π-donor Cl and π-acceptor cyano groups favors the increased stability of the CHClCN radical, but a competition of the two substituents is observed in the singlet-triplet splitting of the carbene. The experimental results are consistent with high level ab-initio calculations using the spin-flip approach in combination with the coupled-cluster theory. The C-H bond dissociation energies were determined for several substituted methanes and discussed. Additionally, a practical model is presented for describing the energy dependence of laboratory-frame photoelectron angular distributions in direct photodetachment from (in principle) any molecular orbital using linearly polarized light. A transparent mathematical approach is used to generalize the Cooper-Zare central-potential model to initial states of any mixed character. In the limits of atomic photodetachment or photoionization, the model reproduces the Cooper-Zare formula. In the case of electron emission from an orbital described as a superposition of s- and p-type functions, the model yields the previously obtained s-p mixing formula. The formalism is further advanced using the Hanstorp approximation, valid for anion photodetachment only, whereas the relative scaling of the partial wave cross-sections is assumed to follow the Wigner threshold law. The resulting model can be used to describe the energy dependence of photoelectron anisotropy for any atomic, molecular, or cluster anions. As a benchmark case, we compare the predictions of the p-d variant of the model to the experimental results for NO⁻ photodetachment and show that the observed anisotropy trend is described well using physically meaningful values of the model parameters.

No description available.