Scaling Relation for Excitation Energy Under Hyperbolic Deformation

We introduce a one-parameter deformation for one-dimensional (1D) quantum lattice models, the hyperbolic deformation, where the scale of the local energy is proportional to cosh lambda j at the j-th site. Corresponding to a 2D classical system, the deformation does not strongly modify the ground state. In this situation, the effective Hamiltonian of the quantum system shows that the quasi particle is weakly bounded around the center of the system. By analyzing this binding effect, we derive scaling relations for the mean-square width of confinement, the energy correction with respect to the excitation gap \Delta, and the deformation parameter $\lambda$. This finite-size scaling allows us to investigate excitation gap of 1D non-deformed bulk quantum systems.Comment: 9 pages, 5 figure

Using Raman Spectroscopy for Intraoperative Margin Analysis in Breast Conserving Surgery

Breast Conserving Surgery (BCS) in the treatment of breast cancer aims to provide optimal oncological results, with minimal tissue excision to optimise cosmetic outcome. Positive margins due to an inadequate resection occurs in 17% of UK patients undergoing BCS and prompts recommendation for further tissue re-excision to reduce recurrence risk. A second operation causes patient anxiety and significant healthcare costs. This issue could be resolved with accurate intra-operative margin analysis (IMA) to enable excision of all cancerous tissue at the index procedure. High wavenumber Raman Spectroscopy (HWN RS) is a vibrational spectroscopy highly sensitive to changes in protein/lipid environment and water content –biochemical differences found between tumour and normal breast tissue. We proposed that HWN RS could be used to differentiate between tumour and non-tumour breast tissue with a view to future IMA. This thesis presents the development of a Raman system to measure the HWN region capable of accurately detecting changes in protein, lipid and water content, in the presence of highly fluorescent surgical pigments such as blue dye that are present in surgically excised specimens. We investigate the relationship between changes in the HWN spectra with changes in water content in constructed breast phantoms to mimic protein and lipid rich environments and biological tissue. Human breast tissue of paired tumour and non-tumour samples were then measured and analysed. We found that breast tumour tissue is a protein rich, high water, low fat environment and that non-tumour is a low protein, fat rich environment with a low water content, and this can be used to identify breast cancer using HWN RS with excellent accuracy of over 90%. This thesis demonstrates a HWN RS Raman system capable of differentiating between tumour and non-tumour tissue in human breast tissue, and this has the potential to provide IMA in BCS

Discovering Constructivism: How A Project-Oriented Activity-Based Media Production Course Effectively Employed Constructivist Teaching Principles

The author uses his experience leading a project-oriented special-topics course as a case study in constructivist teaching methods. Citing relevant literature from the education field, this paper considers why students chosen to work for course credit on a promotional video for a university program considered the project their greatest academic learning experience. The author points out that communication media education has long championed activity and project-based learning and argues that educators could benefit from a deeper understanding of how and why such methods are effective

Low-energy excitations of the one-dimensional half-filled SU(4) Hubbard model with an attractive on-site interaction: Density-matrix renormalization-group calculations and perturbation theory

We investigate low-energy excitations of the one-dimensional half-filled SU(4) Hubbard model with an attractive on-site interaction U < 0 using the density matrix renormalization group method as well as a perturbation theory. We find that the ground state is a charge density wave state with a long range order. The ground state is completely incompressible since all the excitations are gapful. The charge gap which is the same as the four-particle excitation gap is a non-monotonic function of U, while the spin gap and others increase with increasing |U| and have linear asymptotic behaviors.Comment: 4 pages, 3 figures, submitte

Many-body approach to the nonlinear interaction of charged particles with an interacting free electron gas

We report various many-body theoretical approaches to the nonlinear decay rate and energy loss of charged particles moving in an interacting free electron gas. These include perturbative formulations of the scattering matrix, the self-energy, and the induced electron density. Explicit expressions for these quantities are obtained, with inclusion of exchange and correlation effects.Comment: 11 pages, 5 figures. To appear in Journal of Physics