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Open Access Publications from the University of California

Scholarly Works (5 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2016)

In this work, phase-based methods for emerging applications implemented with advanced CMOS technology are proposed. We use phase-based methods to solve problems in high- speed chip-chip/chip-memory data link interconnect, and in terahertz system.

With increasing demand for bandwidth between chip-chip and chip-memory communication, high-speed data link interconnect becomes a key block in modern computer systems. In or- der to serve portable devices, energy efficiency is a critical metric for data link interconnect. Multiband RF Interconnect, which transmits data by upconverts data streams into multiple frequency bands, can fully exploit the bandwidth of interconnect wire with excellent energy efficiency. In order to demodulate data stream, a correct carrier phase in receiver end is necessary. The conventional way for carrier phase synchronization requires high-speed, high- resolution analog-to-digital converter, which consumes large amount of power and silicon area. In the proposed phase-based method, a pilot signal is sent by transmit side, and in receiver end a simple comparator is sufficient to identify correct phase. This greatly enhances energy efficiency of data link and reduces cost. In addition, optimal demodulation phase for dispersive channel is derived.

The other proposed application for phase-based method is terahertz systems. CMOS tera- hertz source suffer from low device cut-off frequency, and fundamental frequency is limited.

Conventional time-domain harmonic extraction can selectively enhance certain harmonic of fundamental tone at output radiation and suppress other harmonics, and therefore increase effective radiation frequency. In terahertz band, time-domain harmonic extraction cannot achieve sufficient low-order harmonic suppression. A spatial-domain harmonic extraction method is proposed, which samples signal in specific spatial positions and combines sampled signals together to selectively enhance and eliminate tones. With proposed method, 1.4-THz CMOS imaging is achieved. In addition, a fast characterization method for terahertz source is proposed. This method uses random sampling (compressive sensing), and reconstruct sparse spectral profile by two-step zoom-in algorithm. With proposed method, a 8X time re- duction can be achieved for terahertz source characterization, which enables regular self-test of terahertz systems.

    Cover page: Phase-Based Algorithms for Communication and Signal Processing
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2017)
    Integrin binding to bioengineered hydrogel scaffolds is essential for tissue regrowth and regeneration, yet not all integrin binding can lead to tissue repair. Here, we show that through engineering hydrogel materials to promote α3/α5β1 integrin binding, we can promote the formation of a space-filling and mature vasculature compared with hydrogel materials that promote αvβ3 integrin binding. In vitro, α3/α5β1 scaffolds promoted endothelial cells to sprout and branch, forming organized extensive networks that eventually reached and anastomosed with neighbouring branches. In vivo, α3/α5β1 scaffolds delivering vascular endothelial growth factor (VEGF) promoted non-tortuous blood vessel formation and non-leaky blood vessels by 10 days post-stroke. In contrast, materials that promote αvβ3 integrin binding promoted endothelial sprout clumping in vitro and leaky vessels in vivo. This work shows that precisely controlled integrin activation from a biomaterial can be harnessed to direct therapeutic vessel regeneration and reduce VEGF-induced vascular permeability in vivo.
      Cover page: Hydrogels with precisely controlled integrin activation dictate vascular patterning and permeability
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2017)
      Currently, there is a limited ability to interactively study developmental cardiac mechanics and physiology. We therefore combined light-sheet fluorescence microscopy (LSFM) with virtual reality (VR) to provide a hybrid platform for 3D architecture and time-dependent cardiac contractile function characterization. By taking advantage of the rapid acquisition, high axial resolution, low phototoxicity, and high fidelity in 3D and 4D (3D spatial + 1D time or spectra), this VR-LSFM hybrid methodology enables interactive visualization and quantification otherwise not available by conventional methods, such as routine optical microscopes. We hereby demonstrate multiscale applicability of VR-LSFM to (a) interrogate skin fibroblasts interacting with a hyaluronic acid-based hydrogel, (b) navigate through the endocardial trabecular network during zebrafish development, and (c) localize gene therapy-mediated potassium channel expression in adult murine hearts. We further combined our batch intensity normalized segmentation algorithm with deformable image registration to interface a VR environment with imaging computation for the analysis of cardiac contraction. Thus, the VR-LSFM hybrid platform demonstrates an efficient and robust framework for creating a user-directed microenvironment in which we uncovered developmental cardiac mechanics and physiology with high spatiotemporal resolution.
        Cover page: Integrating light-sheet imaging with virtual reality to recapitulate developmental cardiac mechanics.
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2022)
        Uveal melanoma (UM) is the most common intraocular tumor in adults. Recurrent mutations in BRCA1-associated protein 1 (BAP1) and splicing factor 3B subunit 1 (SF3B1) display a mutually exclusive pattern in UM, but the underlying mechanism is unknown. We show that combined BAP1 deficiency and SF3B1 hotspot mutation lead to senescence and growth arrest in human UM cells. Although p53 protein expression is induced, deletion of TP53 (encoding p53) only modestly rescues the observed senescent phenotype. UM cells with BAP1 loss or SF3B1 mutation are more sensitive to chemotherapeutic drugs compared with their isogenic parental cells. Transcriptome analysis shows that DNA-repair genes are downregulated upon co-occurrence of BAP1 deletion and SF3B1 mutation, thus leading to impaired DNA damage response and the induction of senescence. The co-occurrence of these two mutations reduces invasion of UM cells in zebrafish xenograft models and suppresses growth of melanoma xenografts in nude mice. Our findings provide a mechanistic explanation for the mutual exclusivity of BAP1 and SF3B1 mutations in human UM.
          Cover page: Co‐occurrence of BAP1 and SF3B1 mutations in uveal melanoma induces cellular senescence
          • Article
          • Peer Reviewed
          UCLA Previously Published Works (2020)
          Currently, there is a limited ability to interactively study developmental cardiac mechanics and physiology. We therefore combined light-sheet fluorescence microscopy (LSFM) with virtual reality (VR) to provide a hybrid platform for 3D architecture and time-dependent cardiac contractile function characterization. By taking advantage of the rapid acquisition, high axial resolution, low phototoxicity, and high fidelity in 3D and 4D (3D spatial + 1D time or spectra), this VR-LSFM hybrid methodology enables interactive visualization and quantification otherwise not available by conventional methods, such as routine optical microscopes. We hereby demonstrate multiscale applicability of VR-LSFM to (a) interrogate skin fibroblasts interacting with a hyaluronic acid–based hydrogel, (b) navigate through the endocardial trabecular network during zebrafish development, and (c) localize gene therapy-mediated potassium channel expression in adult murine hearts. We further combined our batch intensity normalized segmentation algorithm with deformable image registration to interface a VR environment with imaging computation for the analysis of cardiac contraction. Thus, the VR-LSFM hybrid platform demonstrates an efficient and robust framework for creating a user-directed microenvironment in which we uncovered developmental cardiac mechanics and physiology with high spatiotemporal resolution.A user-directed perspective for studying cardiac mechanics, physiology, and developmental biology at single-cell resolution.
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