Imaging Three-Dimensional Single Molecule Dynamics in its Cellular Context

Three-dimensional single molecule microscopy enables the study of dynamic processes in living cells at the level of individual molecules. Multifocal plane microscopy (MUM) is an example of such a modality and has been shown to be capable of capturing the rapid subcellular trafficking of single molecules in thick samples by simultaneously imaging distinct focal planes within the sample. Regardless of the specific modality, however, the obtained 3D trajectories of single molecules often do not fully reveal the biological significance of the observed dynamics. This is because the missing cellular context is often also needed in order to properly understand the events observed at the molecular level. We introduce the remote focusing-MUM (rMUM) modality, which enables 3D single molecule imaging with the simultaneous z-stack imaging of the surrounding cellular structures. Using rMUM, we demonstrate the 3D tracking of prostate-specific membrane antigen (PSMA) with a PSMA-specific antibody in a prostate cancer cell. PSMA is an important biomarker for prostate cancer cells. As such, it is a common target for antibody-based therapies. For example, of particular interest is the use of PSMA-specific antibodies that are conjugated with a toxin that kills prostate cancer cells. We analyze here the pathways of PSMA-specific antibodies, from prior to their first binding to PSMA at the plasma membrane to their arrival at, and continued movement in, sorting endosomes. By making possible the observation of single molecule dynamics within the relevant cellular context, rMUM allows, in our current application, the identification and analysis of different stages of the PSMA-specific antibody trafficking pathway

III-V Nanostructures for Photovoltaics Applications

The concept of introducing an intermediate band to overcome the efficiency limit of single-bandgap solar cells was proposed by Luque and Martí in 1997. It is predicted that utilising the intermediate band for multi-photon absorption can significantly improve the photocurrent generation without accompanying output voltage loss. Amongst several approaches to develop an intermediate band solar cell, quantum dots have drawn much attention as intermediate band due to their three-dimensional quantum confinement and bandgap tunability. However, despite the effort expended so far, there still remains several major challenges that prevent the successful implementation of quantum dot intermediate band solar cells. The work reported in this thesis aims to provide solutions to the main challenges in implementing high-efficiency quantum dot solar cells. The work involves the design, epitaxial growth by molecular beam epitaxy, device processing, and characterisation of QDSCs. This thesis first investigates the influence of direct Si doping on InAs/GaAs quantum dot solar cells with AlAs cap layers. Si doping in QDs leads to state filling of the intermediate band, which is one of the key requirements for a high-efficiency intermediate band solar cell. Moreover, the introduction of moderate amount of Si dopants leads to passivation of defect states, and hence prolongs the carrier lifetime and increases the open-circuit voltage. Secondly, type-II InAs/GaAsSb quantum dot solar cells are studied. Increased photocurrent contribution from the quantum dot region is observed due to the prolonged carrier lifetime associated with the type-II band alignment. Lastly, different types and positions of quantum dot doping methods are investigated. The photoluminescence spectra indicate that using delta or modulation doping in quantum dots can reduce the degradation of crystal quality, and hence decrease the number of non-radiative recombination centres, when compared with using direct doping

MarioNETte: Few-shot Face Reenactment Preserving Identity of Unseen Targets

When there is a mismatch between the target identity and the driver identity, face reenactment suffers severe degradation in the quality of the result, especially in a few-shot setting. The identity preservation problem, where the model loses the detailed information of the target leading to a defective output, is the most common failure mode. The problem has several potential sources such as the identity of the driver leaking due to the identity mismatch, or dealing with unseen large poses. To overcome such problems, we introduce components that address the mentioned problem: image attention block, target feature alignment, and landmark transformer. Through attending and warping the relevant features, the proposed architecture, called MarioNETte, produces high-quality reenactments of unseen identities in a few-shot setting. In addition, the landmark transformer dramatically alleviates the identity preservation problem by isolating the expression geometry through landmark disentanglement. Comprehensive experiments are performed to verify that the proposed framework can generate highly realistic faces, outperforming all other baselines, even under a significant mismatch of facial characteristics between the target and the driver.Comment: In AAAI 202

Self-Calibrating, Fully Differentiable NLOS Inverse Rendering

Existing time-resolved non-line-of-sight (NLOS) imaging methods reconstruct hidden scenes by inverting the optical paths of indirect illumination measured at visible relay surfaces. These methods are prone to reconstruction artifacts due to inversion ambiguities and capture noise, which are typically mitigated through the manual selection of filtering functions and parameters. We introduce a fully-differentiable end-to-end NLOS inverse rendering pipeline that self-calibrates the imaging parameters during the reconstruction of hidden scenes, using as input only the measured illumination while working both in the time and frequency domains. Our pipeline extracts a geometric representation of the hidden scene from NLOS volumetric intensities and estimates the time-resolved illumination at the relay wall produced by such geometric information using differentiable transient rendering. We then use gradient descent to optimize imaging parameters by minimizing the error between our simulated time-resolved illumination and the measured illumination. Our end-to-end differentiable pipeline couples diffraction-based volumetric NLOS reconstruction with path-space light transport and a simple ray marching technique to extract detailed, dense sets of surface points and normals of hidden scenes. We demonstrate the robustness of our method to consistently reconstruct geometry and albedo, even under significant noise levels

A STUDY ON THE SENSITIVITY ANALYSIS OF THE HYDRODYNAMIC DERIVATIVES ON THE MANEUVERABILITY OF KVLCC2 IN SHALLOW WATER

To assess the manoeuvrability of ships in shallow water at the early design stage, reliable simulation models which present shallow water effect are required. However, studies on the manoeuvrability of ship at low speeds in shallow water have been performed less than manoeuvrability in deep water. Also, the limitation of model that the effects of the keel clearance on manoeuvrability are applied to has been validated through previous studies. In this study, the manoeuvrability characteristics of the ship sailing in shallow water at low speed are evaluated by applying the mathematical model considering the shallow water effect. And the sensitivity analysis on shallow water manoeuvring simulation is performed in order to determine hydrodynamic derivatives which are necessary to be derived exactly due to the limitation of the shallow water model used in previous studies. Through this study, it could be confirmed that great importance of estimation of manoeuvrability could be found through the sensitivity index factor of hydrodynamic derivatives changing in the situation operating the shallow water at low speed