DSpace Collection:
http://hdl.handle.net/2115/20136
2020-08-12T16:33:14ZMathematical Study on Fluorescence Diffuse Optical Tomography : Recovering the Distribution of Fluorophores Using Cuboid Approximation
http://hdl.handle.net/2115/78942
Title: Mathematical Study on Fluorescence Diffuse Optical Tomography : Recovering the Distribution of Fluorophores Using Cuboid Approximation
Authors: Sun, Chunlong
Abstract: In this thesis the time-domain fluorescence diffuse optical tomography (FDOT) is theoretically and numerically investigated based on analytical expressions for a three space dimensional diffusion equation model (DE model). Physically the radiative transfer equation model (RTE model) is a better model to describe the physical process behind the measurement of the FDOT. We carefully analyzed the derivation of the DE model from RTE model to consider about the modelling error. Since the distance between the source and detectors are short, the initial boundary value problem for the DE can be considered in the half space. Here there are two diffusion equations coupled in one of its source term. Each of them describes the emission of angularly averaged excited photon density (i.e.excited light) and that of emitted photon density (i.e. emitted light). Usually for the excited light the distribution of fluorophores in biological tissue is ignored and have the so called linearized DE model. The emission light is analytically calculated by solving an initial boundary value problem for coupled diffusion equations in the half space. Based on the analytic expression of the solution to this initial boundary value problem, we establish an error estimate for linearizing the DE model.Our FDOT is to recover the distribution of fluorophores in biological tissue based on the linearized DE model by using the time-resolved measurement data on the boundary surface. We theoretically analyzed the identifiability of this inverse absorption problem. Aiming a fast and robust algorithm for our FDOT inverse problem, we identify the location of a fluorescence target by assuming that it has a cuboidal shape neglecting its precise shape. We proposed and verified our inversion strategy which is a combination of theoretical arguments and numerical arguments for an inversion, which enables to obtain a stable inversion and accelerate the speed of convergence. Its effectivity and performance were tested numerically using simulated data and experimental data obtained from ex vivo beef phantoms.2020-06-29T15:00:00ZSun, ChunlongIn this thesis the time-domain fluorescence diffuse optical tomography (FDOT) is theoretically and numerically investigated based on analytical expressions for a three space dimensional diffusion equation model (DE model). Physically the radiative transfer equation model (RTE model) is a better model to describe the physical process behind the measurement of the FDOT. We carefully analyzed the derivation of the DE model from RTE model to consider about the modelling error. Since the distance between the source and detectors are short, the initial boundary value problem for the DE can be considered in the half space. Here there are two diffusion equations coupled in one of its source term. Each of them describes the emission of angularly averaged excited photon density (i.e.excited light) and that of emitted photon density (i.e. emitted light). Usually for the excited light the distribution of fluorophores in biological tissue is ignored and have the so called linearized DE model. The emission light is analytically calculated by solving an initial boundary value problem for coupled diffusion equations in the half space. Based on the analytic expression of the solution to this initial boundary value problem, we establish an error estimate for linearizing the DE model.Our FDOT is to recover the distribution of fluorophores in biological tissue based on the linearized DE model by using the time-resolved measurement data on the boundary surface. We theoretically analyzed the identifiability of this inverse absorption problem. Aiming a fast and robust algorithm for our FDOT inverse problem, we identify the location of a fluorescence target by assuming that it has a cuboidal shape neglecting its precise shape. We proposed and verified our inversion strategy which is a combination of theoretical arguments and numerical arguments for an inversion, which enables to obtain a stable inversion and accelerate the speed of convergence. Its effectivity and performance were tested numerically using simulated data and experimental data obtained from ex vivo beef phantoms.Mathematical Study on Fluorescence Diffuse Optical Tomography : Recovering the Distribution of Fluorophores Using Cuboid Approximation [an abstract of dissertation and a summary of dissertation review]
http://hdl.handle.net/2115/78941
Title: Mathematical Study on Fluorescence Diffuse Optical Tomography : Recovering the Distribution of Fluorophores Using Cuboid Approximation [an abstract of dissertation and a summary of dissertation review]
Authors: Sun, Chunlong2020-06-29T15:00:00ZSun, ChunlongTowards the interpretation of complex visual hallucinations in terms self-reorganization of neural networks.
http://hdl.handle.net/2115/78940
Title: Towards the interpretation of complex visual hallucinations in terms self-reorganization of neural networks.
Authors: 藤堂, 真登2020-06-29T15:00:00Z藤堂, 真登Towards the interpretation of complex visual hallucinations in terms self-reorganization of neural networks. [an abstract of dissertation and a summary of dissertation review]
http://hdl.handle.net/2115/78939
Title: Towards the interpretation of complex visual hallucinations in terms self-reorganization of neural networks. [an abstract of dissertation and a summary of dissertation review]
Authors: 藤堂, 真登2020-06-29T15:00:00Z藤堂, 真登Semigroups and Geometry, and Link invariants constructed by semigroups
http://hdl.handle.net/2115/78938
Title: Semigroups and Geometry, and Link invariants constructed by semigroups
Authors: 宮谷, 俊典2020-06-29T15:00:00Z宮谷, 俊典Semigroups and Geometry, and Link invariants constructed by semigroups [an abstract of dissertation and a summary of dissertation review]
http://hdl.handle.net/2115/78937
Title: Semigroups and Geometry, and Link invariants constructed by semigroups [an abstract of dissertation and a summary of dissertation review]
Authors: 宮谷, 俊典2020-06-29T15:00:00Z宮谷, 俊典Study on the COX-2/PGE2 Pathway on Apical Elimination of RasV12-transformed Cells from Epithelia
http://hdl.handle.net/2115/78918
Title: Study on the COX-2/PGE2 Pathway on Apical Elimination of RasV12-transformed Cells from Epithelia
Authors: 佐藤, 奈波
Abstract: At the initial stage of carcinogenesis, when RasV12-transformed cells are surrounded by normal epithelial cells, RasV12 cells are often extruded from the apical lumen of the epithelial layer through cell competition with the surrounding normal cells. However, the underlying molecular mechanisms of this cancer preventive process are not fully understood. In this study, we first demonstrate that expression of cyclooxygenase (COX)2 is transcriptionally upregulated in normal epithelial cells that surround RasV12transformed cells in a non-cell-autonomous manner. Addition of COX inhibitor or COX2-knockout in normal cells promotes apical extrusion of RasV12 cells. Furthermore, production of Prostaglandin (PG) E2, a downstream prostanoid of COX-2, is elevated in normal cells surrounding RasV12 cells. Addition of PGE2 suppresses apical extrusion of RasV12 cells, while PGE2 synthase inhibitor enhances it. In a cell competition mouse model, expression of COX-2 is elevated in pancreatic epithelia harbouring RasV12exressing cells, and administration of the COX inhibitor ibuprofen promotes apical extrusion of RasV12 cells. Moreover, caerulein-induced chronic inflammation substantially suppresses apical elimination of RasV12 cells. These results indicate that intrinsically or extrinsically mediated inflammation can promote tumour initiation by diminishing cell competition between normal and transformed cells.2020-06-29T15:00:00Z佐藤, 奈波At the initial stage of carcinogenesis, when RasV12-transformed cells are surrounded by normal epithelial cells, RasV12 cells are often extruded from the apical lumen of the epithelial layer through cell competition with the surrounding normal cells. However, the underlying molecular mechanisms of this cancer preventive process are not fully understood. In this study, we first demonstrate that expression of cyclooxygenase (COX)2 is transcriptionally upregulated in normal epithelial cells that surround RasV12transformed cells in a non-cell-autonomous manner. Addition of COX inhibitor or COX2-knockout in normal cells promotes apical extrusion of RasV12 cells. Furthermore, production of Prostaglandin (PG) E2, a downstream prostanoid of COX-2, is elevated in normal cells surrounding RasV12 cells. Addition of PGE2 suppresses apical extrusion of RasV12 cells, while PGE2 synthase inhibitor enhances it. In a cell competition mouse model, expression of COX-2 is elevated in pancreatic epithelia harbouring RasV12exressing cells, and administration of the COX inhibitor ibuprofen promotes apical extrusion of RasV12 cells. Moreover, caerulein-induced chronic inflammation substantially suppresses apical elimination of RasV12 cells. These results indicate that intrinsically or extrinsically mediated inflammation can promote tumour initiation by diminishing cell competition between normal and transformed cells.Study on the COX-2/PGE2 Pathway on Apical Elimination of RasV12-transformed Cells from Epithelia [an abstract of dissertation and a summary of dissertation review]
http://hdl.handle.net/2115/78917
Title: Study on the COX-2/PGE2 Pathway on Apical Elimination of RasV12-transformed Cells from Epithelia [an abstract of dissertation and a summary of dissertation review]
Authors: 佐藤, 奈波2020-06-29T15:00:00Z佐藤, 奈波Studies on freely infinitely divisible distributions
http://hdl.handle.net/2115/78464
Title: Studies on freely infinitely divisible distributions
Authors: 植田, 優基2020-03-24T15:00:00Z植田, 優基Studies on freely infinitely divisible distributions [an abstract of dissertation and a summary of dissertation review]
http://hdl.handle.net/2115/78463
Title: Studies on freely infinitely divisible distributions [an abstract of dissertation and a summary of dissertation review]
Authors: 植田, 優基2020-03-24T15:00:00Z植田, 優基