No description available.

No description available.

No description available.

Raman Spectroscopy for the identification and classification of malignancy in the oesophagus has been demonstrated in this thesis. The potential of Raman spectroscopy in this field is twofold; as a adjunct for the pathologist and as a biopsy targeting tool at endoscopy. This study has demonstrated the feasibility of these potential applications in vitro. Spectral diagnostic models have been developed by correlating spectral information with histopathology. This is the current 'gold standard' diagnostic method for the identification of dysplasia, the established risk factor for the development of oesophageal cancer. Histopathology is a subjective assessment and widely acknowledged to have limitations. A more rigorous gold standard was therefore developed, as part of this study, using the consensus opinion of three independent expert pathologists to train the diagnostic models. Raman spectra have been measured from oesophageal tissue covering the full spectrum of malignant disease in the oesophagus, using a near infrared Raman spectrometer customised for tissue spectral measurements. Two spectral datasets were measured with different volumes of tissue probed using twenty and eighty times magnification ultra long working distance objectives. Multivariate statistical analysis has been used to extract the required spectral information with the greatest discriminative power. Principal component fed linear discriminant spectral models have been tested with leave one out cross validation procedures. Three pathology group models have correctly classified up to 91% of spectra, and eight group models have correctly classified up to 82% of spectra. Optimisation of the spectral models by selection of significant principal components, filtering the data and using staggered models was investigated. Effort has been made to understand the findings in their clinical context, with review of patient history and clinical progress, long term follow up is required. Preliminary work projecting independent data on to the models has been encouraging with 76% of the spectra in the three group model correctly classified, approaching classification levels of the training dataset. Formalin fixed tissue models were demonstrated to perform well, with 80% of the spectra were correctly classified in the seven group model. This further demonstrates the potential of Raman spectroscopy as a pathology tool. If Raman spectroscopy is to be implemented in a clinical setting it must be transferable between different measurement systems. This has been evaluated with oesophageal tissue spectra measured on two systems using three objectives. Simple calibration has demonstrated the use of multiple systems and measurement parameters in the development and application of spectral classification models. Testing of a new design of fibre probe has provided encouraging preliminary results. There is potential for the application of Raman spectroscopy in vivo, however the technology remains immature. Spectral maps of samples taken from across the spectrum of disease have shown clear delineation of the morphological features seen on the H&E images. Furthermore the biochemical information elicited has been analysed. Initial measurements of oesophageal tissue using multiphoton imaging have demonstrated the potential of collagen autofuorescence in the diagnosis of malignant change.

Quantum mechanics and atomic, molecular, optical (AMO) physics have been widely studied in the past century. This dissertation covers several topics in the field of AMO physics that were the focus of my Ph.D. studies, both theoretical and computational.<div><br></div><div>The first topic is related to trapping of Rydberg atoms inside an optical trap. The study focuses on the trapping energy and state mixing of Rydberg atoms based on different angular momentum state and spin-orbit coupling of the Rydberg electron. </div><div><br></div><div>The second topic is the two-electron correlations in an atom, especially double Rydberg wave packets. We have focused on the rapid autoionization and angular momentum exchanges between the double Rydberg wave packets. Then, the study of two-electron correlation is extended to the post-collision interaction (PCI) in Auger decay and a sequential ionization model. Quantum interference patterns can be found in the final correlated distributions. In the PCI study, quantum calculations and semiclassical calculations are performed to interpret the interference patterns. </div><div><br></div><div>The last topic is the ionization behavior of one-electron Rydberg atoms from a terahertz single-cycle pulse. We investigate and compare the different ionization probabilities of a Rydberg electron from an initial stationary state and a wave packet. Also, studies of the ionization behavior are extended to scaled parameters, where all physical parameters of the electron and field pulses are scaled.</div>

Através do uso de pseudopotenciais e possível simplificarmos o calculo de estrutura eletrônica de átomos, moléculas ou sólidos, pois não ha necessidade de incluirmos os orbitais de caroço. Entretanto, tais pseudopotenciais ainda não foram utilizados em cálculos de espalhamento, havendo a necessidade de serem testados. Realizamos um estudo utilizando os pseudopotenciais de Bachelet, Hamann e Schluter em cálculos de espalhamento de elétrons por átomos, calculando phase shifts e seções de choque para momentos angulares 1=0, 1 e 2 com elétrons incidentes possuindo energia ate 5ry. Comparamos os resultados obtidos com o uso dos pseudopotenciais e do potencial de todos os elétrons, os quais se mostraram em ótimo acordo, existindo, porem, restrições na faixa de energia em que os cálculos podem ser realizados. Visamos, desta forma, simplificar o calculo de espalhamento por moléculas complexas. / Pseudopotentials allow an extraordinary simplification in the calculation of the electronic structure of atoms, molecules and crystals. Though they have benn used extensively for electronic structure calculations, little is known of their applicability to scattering. We made a study of the pseudopotentials of Bacheket, Hamann and Schlüter in the electron scattering by atoms, calculating phase-shifts and cross sections for angular moments 1=0,1 and energy up to 5Ry. We compare the results for the pseudopotential with the all-electron calculation. The agreement is very good in a broad energy band. We aim at simplifying the calculation of scattering by complex molecules where an all-electron calculation is impossible.

Desenvolvemos neste trabalho, um formalismo alternativo de \"dois níveis\" sugerido por Cattani, para o cálculo dos alargamentos e deslocamentos de linhas espectrais produzidos por colisões, quando é valida a aproximação de impacto. Este formalismo foi usado para calcular alargamentos e deslocamentos eletrônicos de algumas linhas do átomo de hélio neutro em um plasma, para as quais, foi possível aplicar a teoria de \"dois níveis\". A contribuição das colisões iônicas aos alargamentos e deslocamentos das linhas espectrais foi avaliada, utilizando a aproximação quase estática de Griem, Baranger, Kolb e Oertel. Os resultados dos cálculos foram comparados com os resultados experimentais de Kelleher, Berg e colaboradores, Wulff e Diatta e com as previsões dos formalismos, convergente e de corte. / In this work we develop an alternative formalism of \"two levels\" suggested by Cattani to the calculation of widths and shifts of spectral lines produced by collisions, in the impact approximation. This formalism was used to calculate in a plasma the electronic widths and shifts of neutral helium lines for which is valid the \"two levels\" approach. To take into account the ions contribution to the widths and shifts of the lines, we have . used the quasistatic approximation of Griem, Baranger, Kolb and Oertel. Our theoretical predictions are compared with the experimental results of Kelleher, Berg and collaborators, Wulff and Diatta and also with the predictions of the convergent and cutoff formalisms.

No description available.

No description available.

This thesis is concerned with aspects of quantum theory of fields in flat and curved spacetimes of arbitrary dimensions along with detecting bosons and fermions on these spacetimes. The thesis is divided into two main parts. In the first part, we analyse an Unruh-DeWitt particle detector that is coupled linearly to the scalar density of a massless Dirac field (neutrino field) in Minkowski spacetimes of dimension d ≥ 2 and on the two-dimensional static Minkowski cylinder, allowing the detector’s motion to remain arbitrary and working to leading order in perturbation theory. In d-dimensional Minkowski spacetime, with the field in the usual Fock vacuum, we show that the detector’s response is identical to that of a detector coupled linearly to a massless scalar field in 2d-dimensional Minkowski. In the special case of uniform linear acceleration, the detector’s response hence exhibits the Unruh effect with a Planckian factor in both even and odd dimensions, in contrast to the Rindler power spectrum of the Dirac field, which has a Planckian factor for odd d but a Fermi-Dirac factor for even d. On the two-dimensional cylinder, we set the oscillator modes in the usual Fock vacuum but allow an arbitrary state for the zero mode of the periodic spinor. We show that the detector’s response distinguishes the periodic and antiperiodic spin structures, and the zero mode of the periodic spinor contributes to the response by a state-dependent but well defined amount. Explicit analytic and numerical results on the cylinder are obtained for inertial and uniformly accelerated trajectories, recovering the d = 2 Minkowski results in the limit of large circumference. The detector’s response has no infrared ambiguity for d = 2, neither in Minkowski nor on the cylinder. In the second part, firstly, we give a thorough discussion for the Bogolubov transformation for Dirac field, and discuss pair creation in a non-stationary spacetime. Secondly, we derive the in and out vacua Wightman two-point functions for the Dirac field and the Klein-Gordon field for certain class of spatially flat Friedmann-Robertson-Walker (FRW) cosmological spacetimes wherein the two-point functions have the Hadamard form. We then establish the equivalence between the adiabatic vacuum of infinite order and the conformal vacuum in the massless limit. With the field in the conformal Fock vacuum, we then show that the detector’s response to an UDW particle detector coupled linearly to the scalar density of a massless Dirac field in the spatially flat FRW spacetimes in d-dimensions is identical to the response of a detector coupled to the massless scalar field in the spatially flat FRW spacetimes in 2d-dimensions. Lastly, we discuss a massive scalar field in the spatially compactified (1 + 1)-dimensional FRW spacetime. There, the issue of the conformal zero momentum mode arises. To resolve this issue, we develop a new scheme for quantizing the conformal zero-mode. This new quantization scheme introduces a family of two real parameters for every zero-momentum mode with an associated two-real-parameter set of in/out vacua. We then show that the zero momentum initial state’s wave functional corresponds to a two-real parameter set of Gaussian wave packets. For applications, we examine the finite-time detector’s response to a massive scalar field in the (1 + 1)-dimensional, spatially compactified Milne spacetime. Explicit analytic results are obtained for the comoving and inertially non-comoving trajectories. Numerical results are provided for the comoving trajectory. The numerical results suggest that when the in-vacuum is chosen to be very far from the conventional Minkowski vacuum state, then it contains particles. As result, spontaneous excitation of the comoving detector occurs.