Letian Luo Thesis Statement

My work started out originating from my dreams, but recently it has moved away from that source. To make the cut outs, I would scribble on the back of a small sheet of scarp paper. Then I discovered that if I cut out the scribble, it become more interesting than the dream work. So I developed the scribbles further. I enlarged them, made them more complex and gestural, and then cut them out, meticulously and with painstaking attentiveness. The process allowed me to draw with knife. I very enjoy the process of me making the cut outs. It got increasingly elaborate, almost mural-scale. It takes more time and gives me greater pleasure. The relationship between positive and negative space is important. I make more by taking away more. The more I cut the better result I get. It is important because in the real world, usually the more we take the less it remain. My paper cuts create a very quiet space. There is a calming quality in the paper’s relationship to the white wall. That quietness contrasts dramatically to the noisy world we live in. my works provide an island of respite from color, and noise, inviting viewers to contemplate something different

Understanding the role of regulatory RNAs in human skin wound healing

Human skin wound healing is characterized by four phases in a timely manner, including hemostasis, inflammation, proliferation, and remodeling. Various cell types are involved in the biological process. Keratinocytes that constitute around 95% of epidermal cells recruit immune cells by secreting pro-inflammatory cytokines/chemokines and undergo re-epithelialization in the proliferation phase. Ribonucleic acids (RNAs) without protein-coding capacity, defined as noncoding RNAs, consist of the majority of transcription output, are indispensable for multiple biological processes and are critical during disease contexts. Due to their cell and context specificity, noncoding RNAs present a therapeutic potential. However, revealing their underlying mechanism in the skin wound healing is the prerequisite. In this thesis, we identified and comprehensively characterized the role of long noncoding RNAs (lncRNAs) (Paper I, III, IV) and microRNAs (miRNAs) (Paper II) in human skin wound healing. Paper I identified Wound And Keratinocyte Migration-Associated lncRNA 1 (WAKMAR1), and it was upregulated during wound healing but deficient in nonhealing wounds. WAKMAR1 silencing inhibited keratinocyte migration and re-epithelialization of human ex vivo wounds, whereas its overexpression promoted cell migration. Moreover, we revealed that the WAKMAR1-regulated network composed of pro-migratory genes was driven by E2F Transcription Factor 1 (E2F1). Further mechanistic investigation showed that WAKMAR1 enhanced E2F1 expression by hijacking DNA methyltransferases (DNMTs) and reducing methylation at the E2F1 promoter. This study demonstrates that WAKMAR1 is essential for keratinocyte migration and re-epithelialization of human ex vivo wounds, and its deficiency may be associated with delayed healing. Paper II aimed to identify clinically relevant miRNAs and develop an open database for future studies in skin wound healing. We performed the comprehensive and integrative small and long RNA sequencing analysis in human skin, normal wounds collected at different healing phases, and venous ulcers (VUs). We found 17 VU-relevant miRNAs, whose targets were overrepresented in the VU-specific signature. The upregulated miRNAs in VU were predicted to promote inflammatory response but impair cell proliferation, but the downregulated miRNAs might be needed for cell proliferation and migration. We tested the combined effects of miR-34a-5p, miR-424-5p, and miR-516-5p upregulated in VU. Simultaneous overexpression of miR-34a-5p and miR-424-5p had stronger inhibitory effects on keratinocyte proliferation and migration, whereas the combination of miR-34a-5p and miR-516b-5p promoted the expression of the pro-inflammatory Chemokine (C-C Motif) Ligand 20 (CCL20). Overall, our study identifies VU-relevant miRNAs and demonstrates that their abnormal expression may contribute to the pathogenesis of nonhealing wounds. Paper III investigated the role of the HOXC13 Antisense RNA (HOXC13-AS) in epidermal differentiation. LncRNA HOXC13-AS was specifically expressed in human skin and downregulated in the early phases of wound healing. We analyzed our single-cell RNA sequencing in the human skin and found that HOXC13-AS was highly expressed in the differentiated keratinocytes. Furthermore, we showed that HOXC13-AS was decreased by the epidermal growth factor receptor (EGFR) signaling pathway but gradually increased during keratinocyte differentiation. Transcriptomic analysis and functional assays indicated that HOXC13-AS promoted keratinocyte differentiation using differentiation models in vitro and organotypic epidermis. Mechanistically, we revealed that HOXC13-AS physically interacted with COPI Coat Complex Subunit Alpha (COPA) which is essential for the retrograde transport from the Golgi to the endoplasmic reticulum (ER). HOXC13-AS hijacked COPA, which interfered with the retrograde transport, promoting ER stress and keratinocyte differentiation. Rescue assays confirmed that the role of HOXC13-AS in keratinocyte differentiation was dependent on COPA. Overall, this study demonstrates HOXC13-AS as a molecule of importance for epidermal differentiation. Paper IV focused on lncRNA SNHG26, which plays a key role in the transition from inflammation to proliferation during wound healing. SNHG26 was upregulated during wound healing, and Snhg26 knockout mice showed delayed re-epithelialization. By single-cell RNA sequencing analysis, we found decreased migratory but increased inflammatory keratinocyte progenitors in the wound edge of Snhg26 deficient mice. Moreover, we confirmed that SNHG26 enhanced cell proliferation and migration but inhibited inflammatory response in human keratinocytes and ex vivo wounds. Mechanistically, we demonstrated that Interleukin Enhancer Binding Factor 2 (ILF2) physically interacted with SNHG26 using RNA pulldown and RNA immunoprecipitation (RIP). Chromatin immunoprecipitation (ChIP) and chromatin isolation by RNA purification (ChIRP) sequencing showed that SNHG26 guided ILF2 from the inflammatory genomic loci to the Laminin Subunit Beta 3 (LAMB3) genomic locus, switching the gene network and facilitating the inflammatory-to-proliferative state transition of keratinocyte progenitors. This study provides compelling evidence for SNHG26 being a crucial regulator for human skin wound healing

Dynamic multimedia content access in a ubiquitous and distributed computing environment

Ubiquitous computing is the concept of embedding many heterogeneous devices within our everyday environment in such a way that they operate seamlessly and become transparent to the person using them. It covers a wide range of applications and services, but of particular interest is multimedia resource adaptation which involves customization and dynamic adaptation of resources according to usage environments and user preferences; this aims to provide consumers with transparent access. This thesis proposes a content negotiation architecture for dynamic adaptation of multimedia content according to usage environment attributes. The architecture shields users from complex configuration details related to the adaptation of multimedia content, while guiding them through user related choices. The architecture also dynamically updates the multimedia content during transmission and consumption when related usage environment attributes are changed. The content negotiation mechanism in the proposed architecture is then extended and deployed in a mobile computing environment to accommodate transfer of multimedia content application session state between devices in a seamless manner. An application session transfer architecture which allows sessions to be directed, stored and transferred through an intermediary session server is proposed. The thesis also considers the foregoing work on the adaptation of multimedia resources applied to sharing in a Peer-to-Peer (P2P) network. It proposes a super peer based dynamic resource adaptation architecture which employs \u27pull\u27 and \u27push\u27 two-stage adaptation approach. This guides users through resource search and configuration details without exposing them to unnecessary technical details; the result is that requested content is transparently adapted to heterogeneous terminal devices. Two separate, but related, modifications are proposed to further improve the performance of the proposed P2P architecture. Firstly, peers are clustered according to registered geographic location information and secondly, based on that registered location information, a locality-based service is introduced which allows users to search services according to their geographic locations. The latter encourages service providers to increase the uptime of their devices and hence provide spare computing power for active adaptation of resources for low-end peers. Resource replication is an important aspect of a P2P system and an adaptive resource replication strategy based on the proposed P2P architecture is presented. It uses resource request rate as the metric to trigger the resource replication process, and proportionally replicates multimedia resources into various configuration states according to the properties of peers and the size of peer clusters. Also, the strategy uses peer related information stored on super peers to determine which peers should be selected to perform adaptive replications and where the resulting replicas should be stored. The proposed adaptive replication strategy demonstrates that the network delays are reduced while resource hit rate is increased in comparison to other replication strategies. Investigation of the deployment of a BitTorrent (BT) - like approach in the proposed P2P resource adaptation architecture is also considered in this thesis. In addition, the architecture\u27s peer selection strategy is adopted and evaluated as a way to enhance the peer selection process in BT. The strategy uses super peers as trackers to intelligently select peers according to their capabilities and shared resource segments and overcome the scalability issue of existing BT implementation. The proposed selection strategy reduces average access time and increases download speed when compared with the existing BT peer selection process with randomly selected peers. Also, the deployment of BT in the proposed P2P architecture shows that it greatly reduces the congested download problem which was previously reported

Microstructural evolution in 9 wt.% Cr power plant steels

High chromium ferritic steels such as Grade 91 and Grade 92 are extensively used in the power plant industry. Components made from these types of steels, including headers, steam pipes and tubes, are required to provide reliable service at high pressures (20-30 MPa) and temperatures (550-610°C) for several decades. However, in order to further improve the thermal efficiency of the power plant, the future operation temperature for the ferritic steels needs to be elevated to 650°C. Therefore, the current research project focuses on the examination of recently developed MarBN type steels (Martensitic steel strengthened by Boron and Nitrides) and four Grade 92 derivatives in order to evaluate their suitability for 650°C application, and also to assess their creep strength from a microstructural point of view. [Continues.

E3^3Pose: Energy-Efficient Edge-assisted Multi-camera System for Multi-human 3D Pose Estimation

Multi-human 3D pose estimation plays a key role in establishing a seamless connection between the real world and the virtual world. Recent efforts adopted a two-stage framework that first builds 2D pose estimations in multiple camera views from different perspectives and then synthesizes them into 3D poses. However, the focus has largely been on developing new computer vision algorithms on the offline video datasets without much consideration on the energy constraints in real-world systems with flexibly-deployed and battery-powered cameras. In this paper, we propose an energy-efficient edge-assisted multiple-camera system, dubbed E$^3$Pose, for real-time multi-human 3D pose estimation, based on the key idea of adaptive camera selection. Instead of always employing all available cameras to perform 2D pose estimations as in the existing works, E$^3$Pose selects only a subset of cameras depending on their camera view qualities in terms of occlusion and energy states in an adaptive manner, thereby reducing the energy consumption (which translates to extended battery lifetime) and improving the estimation accuracy. To achieve this goal, E$^3$Pose incorporates an attention-based LSTM to predict the occlusion information of each camera view and guide camera selection before cameras are selected to process the images of a scene, and runs a camera selection algorithm based on the Lyapunov optimization framework to make long-term adaptive selection decisions. We build a prototype of E$^3$Pose on a 5-camera testbed, demonstrate its feasibility and evaluate its performance. Our results show that a significant energy saving (up to 31.21%) can be achieved while maintaining a high 3D pose estimation accuracy comparable to state-of-the-art methods

Cellular receptor binding and entry of human papillomavirus

Human papillomaviruses (HPVs), recognized as the etiological agents for the skin, plantar, genital, and laryngopharyngeal wart, have been previously in numerous studies demonstrated to present a close link between HPV infection and certain human cancers, some putative candidates of HPV cell receptor and possible pathways of cell entry proposed. This review was to highlight the investigations and remaining questions regarding the binding and entry process

Effects of Choline Chloride, Urea and Their Deep Eutectic Solvents on the Modification of Leather

Content: The application of split leather is an important issue in leather industry as most of them was not properly treated and wasted. In this study the application of choline chloride (ChCl), urea (U) and corresponding deep eutectic solvents (DES) on the modification of thermal stability and mechanical strength of mink split leather was investigated. TGA and DSC results indicated DES treatment enhanced thermal stability of split leather, and ChCl treatment reduced the stability. While, U treatment provided a kinetic inhibition during the thermal-decomposition. In terms of the mechanical strength, both ChCl and U treatment reduced burst intensity and extended height. While, after DES treatment the burst intensity and extended height increased significantly. In terms of the dosage, 7% DES provided best performance. Results mentioned above illustrated that DES formed by simply mixing ChCl and U provided strong interaction with fiber, enhanced the crosslinks. A hypothesis of [Ch(Urea)]+[Cl(Urea)]- type structure was proposed, as it enabled DES forming strong hydrogen bonds with functional groups on leather fiber, enhancing the crosslinks and therefore improving the thermal stability and mechanical strength. The DES treatment on leather fibers improved their overall performance and thereby broaden their applications. Take-Away: 1. DES obtained by mixing ChCl and urea presented very different effect in leather treatment, as the thermal stability and physical strength of leather improved significantly after the DES treatment. 2. A hypothesis of [Ch(Urea)]+[Cl(Urea)]- type structure was proposed, illustrating a formation of strong hydrogen bonds between DES and functional groups on leather fiber. This enhances the crosslinks and therefore improves the thermal and mechanical strength of leather