Development of the Engineered Biological Model Systems and Chemoselective Redox Responsive Ligation (CRRL)

Biological model substrates were developed and engineered for cell adhesion and migration studies. The substrates are based on hydroquinone-presenting (HQ) self-assembled monolayers on gold surfaces that can be electrochemically activated for ligand immobilization. Combined with tetra(ethylene glycol)-terminated alkanethiol, the substrates secure biospecific interactions between cell adhesion receptors and ligands, as well as provide the ability to characterize the amount of immobilized ligand. In chapter 2, these model surfaces were used to study the biological role of decoupled PHSRN, found in the 9th type III domain of fibronectin when it is presented to Swiss 3T3 albino mouse fibroblasts. We found that PHSRN-integrin interactions enhanced lamellipodia protrusions by increasing Rac1 activity, which is associated with cross-talk between adhesion receptors and soluble factors. These novel biological model systems were further extended toward the development of a new platform based on reacting soluble ketone- or aldehyde-tethered ligands to surface-bound oxyamine-containing alkanethiols to generate a covalent oxime linkage to the surface in chapter 3. By photoprotecting the oxyamine group with nitroveratryloxycarbonyl chloride and then selectively deprotecting through microfiche film, bioligands and fibroblast cells could be immobilized in patterns and gradients. Expanding on the HQ platform in chapters 1 and 2, a general methodology to immobilize and release oxyamine ligands on an electroactive quinone monolayer by electrochemical reduction was reported in chapter 4. The HQ surface is catalytic, can perform several rounds of immobilization and release of ligands, and also converts the oxyamine functional group to a hydroxyl group by a mild electrochemical potential. In chapter 5, a general chemoselective redox responsive ligation and release strategy for molecular conjugation and cleavage was introduced. The HQ is converted to benzoquinone to form stable quinone oxime with oxyamine-tethered ligands that can be further cleaved by reduction, yielding aminophenol and hydroxyl-terminated ligand. The conjugation and cleavage reactions are controlled by mild chemical or electrochemical redox signals and can be performed at physiological conditions (pH 7.4, 37 oC) without the use of a catalyst

Hybrid-functional and quasi-particle calculations of band structures of Mg2Si, Mg2Ge, and Mg2Sn

We perform hybrid functional and quasi-particle band structure calculations with spin-orbit interaction to investigate the band structures of Mg2Si, Mg2Ge, and Mg2Sn. For all Mg2X materials, where X = Si, Ge, and Sn, the characteristics of band edge states, i.e., band and valley degeneracies, and orbital characters, are found to be conserved, independent of the computational schemes such as density functional generalized gradient approximation, hybrid functionals, or quasi-particle calculations. However, the magnitude of the calculated band gap varies significantly with the computational schemes. Within density-functional calculations, the one-particle band gaps of Mg2Si, Mg2Ge, and Mg2Sn are 0.191, 0.090, and -0.346 eV, respectively, and thus severely underestimated compared to the experimental gaps, due to the band gap error in the density functional theory and the significant relativistic effect on the low-energy band structures. By employing hybrid-functional calculations with a 35% fraction of the exact Hartree-Fock exchange energy (HSE-35%), we overcame the negative band gap issue in Mg2Sn. Finally, in quasi-particle calculations on top of the HSE-35% Hamiltonians, we obtained band gaps of 0.835, 0.759, and 0.244 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively, consistent with the experimental band gaps of 0.77, 0.74, and 0.36 eV, respectively.Comment: 23 pages, including 84 references, 5 tables, 3 figure

Thermal-Infrared Remote Target Detection System for Maritime Rescue based on Data Augmentation with 3D Synthetic Data

This paper proposes a thermal-infrared (TIR) remote target detection system for maritime rescue using deep learning and data augmentation. We established a self-collected TIR dataset consisting of multiple scenes imitating human rescue situations using a TIR camera (FLIR). Additionally, to address dataset scarcity and improve model robustness, a synthetic dataset from a 3D game (ARMA3) to augment the data is further collected. However, a significant domain gap exists between synthetic TIR and real TIR images. Hence, a proper domain adaptation algorithm is essential to overcome the gap. Therefore, we suggest a domain adaptation algorithm in a target-background separated manner from 3D game-to-real, based on a generative model, to address this issue. Furthermore, a segmentation network with fixed-weight kernels at the head is proposed to improve the signal-to-noise ratio (SNR) and provide weak attention, as remote TIR targets inherently suffer from unclear boundaries. Experiment results reveal that the network trained on augmented data consisting of translated synthetic and real TIR data outperforms that trained on only real TIR data by a large margin. Furthermore, the proposed segmentation model surpasses the performance of state-of-the-art segmentation methods.Comment: 12 page

Low-rise high density urban housing in Korea

Thesis (M. Arch)--Massachusetts Institute of Technology, Dept. of Architecture, 1987.Includes bibliographical references (p. 45).The idea of low-rise high-density urban housing is based on two fundamental objectives: 1) To provide higher density by intensifying land use as urban growth escalates at an unprecedented rate. 2) To reconsider the essential qualities of house - a house with a garden, light and air. Modern high-rise apartments provide greater density and improved living conditions in terms of proper sanitation, electricity, and open space. But it lacks individuality and promotes a high degree of anonymity leading to limited social contact between neighbors. It dissociates the house from the ground and creates ambiguous open space between buildings. Single-family detached houses provides individuality and open space but detachment is not only meaningless but highly inefficient in terms of land use The courtyard house provides an alternative solution by combining advantages of individual house and high density housing. Its introverted nature allow dense clustering while maintaining a private open space. The design takes this traditionally horizontal aggregation of dwellings one step further to increase its potential density. It proposes a vertical courtyard house while maintaining access to light and air, visual and acoustical privacy, efficiency of construction, and a revitalization of street life and open space.by Gene S. Park.M.Arc

Imagine the Unseen World: A Benchmark for Systematic Generalization in Visual World Models

Systematic compositionality, or the ability to adapt to novel situations by creating a mental model of the world using reusable pieces of knowledge, remains a significant challenge in machine learning. While there has been considerable progress in the language domain, efforts towards systematic visual imagination, or envisioning the dynamical implications of a visual observation, are in their infancy. We introduce the Systematic Visual Imagination Benchmark (SVIB), the first benchmark designed to address this problem head-on. SVIB offers a novel framework for a minimal world modeling problem, where models are evaluated based on their ability to generate one-step image-to-image transformations under a latent world dynamics. The framework provides benefits such as the possibility to jointly optimize for systematic perception and imagination, a range of difficulty levels, and the ability to control the fraction of possible factor combinations used during training. We provide a comprehensive evaluation of various baseline models on SVIB, offering insight into the current state-of-the-art in systematic visual imagination. We hope that this benchmark will help advance visual systematic compositionality.Comment: Published as a conference paper at NeurIPS 2023. The first two authors contributed equally. To download the benchmark, visit https://systematic-visual-imagination.github.i