MTS-LOF: Medical Time-Series Representation Learning via Occlusion-Invariant Features

Medical time series data are indispensable in healthcare, providing critical insights for disease diagnosis, treatment planning, and patient management. The exponential growth in data complexity, driven by advanced sensor technologies, has presented challenges related to data labeling. Self-supervised learning (SSL) has emerged as a transformative approach to address these challenges, eliminating the need for extensive human annotation. In this study, we introduce a novel framework for Medical Time Series Representation Learning, known as MTS-LOF. MTS-LOF leverages the strengths of Joint-Embedding SSL and Masked Autoencoder (MAE) methods, offering a unique approach to representation learning for medical time series data. By combining these techniques, MTS-LOF enhances the potential of healthcare applications by providing more sophisticated, context-rich representations. Additionally, MTS-LOF employs a multi-masking strategy to facilitate occlusion-invariant feature learning. This approach allows the model to create multiple views of the data by masking portions of it. By minimizing the discrepancy between the representations of these masked patches and the fully visible patches, MTS-LOF learns to capture rich contextual information within medical time series datasets. The results of experiments conducted on diverse medical time series datasets demonstrate the superiority of MTS-LOF over other methods. These findings hold promise for significantly enhancing healthcare applications by improving representation learning. Furthermore, our work delves into the integration of Joint-Embedding SSL and MAE techniques, shedding light on the intricate interplay between temporal and structural dependencies in healthcare data. This understanding is crucial, as it allows us to grasp the complexities of healthcare data analysis.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Contested Geographies of ‘Welcome’: An Ethnographic Analysis of Migrant Reception in Bologna and Torino

After a decade characterized by the leitmotif of “migration crisis,” states in the European Union (EU) are increasingly contending with questions around the integration and long-term membership of migrants to national communities. To pursue the idealized goal of integration, states are increasingly experimenting with programs that bring citizens and migrants together. Examples range from the UNHCR’s Buddies with Refugees initiative to the many state-funded programs that cropped up in 2022, enlisting private citizens in effort to house displaced people from Ukraine. The incorporation of civil society in integration showcases that, states too, see belonging as forged through everyday interactions, mundane adherence to social norms, and the formation of new affective attachments. While civil society is crucial to the existence of integration and “good citizenship” as political projects, it is also an arena to problematize and transform these concepts from the ground up. This dissertation investigates the involvement of civil society in programs developed with the goal of migrant reception and inclusion in Bologna and Torino, Italy. I employed ethnographic methods to investigate how practitioners, city residents, and migrants make sense of the growing role of civil society in initiatives aimed at supporting the long-term integration of migrants. Fieldwork yielded 75 semi-structured interviews, 110 hours of participant observation and a digital archive of more than 500 documents relating to migrant reception in Italy and at the two field sites. Drawing from feminist political geography, urban studies, and critical migration studies, this project investigates the everyday (re)forging of social boundaries and urban ideals of community. This research analyzes how residents, practitioners and migrants come together to rehearse and contest ideas of “welcome” and good community membership. In doing so, this work exposes the continued importance of hospitality as a moral orientation to reception, while underlining hospitality’s many limits as an approach to encounter across difference.Release after 04/30/202

Improving Threat Mitigation Through a Cybersecurity Risk Management Framework: A Computational Design Science Approach

Cyberattacks have been increasing in volume and intensity, necessitating proactive measures. Cybersecurity risk management frameworks are deployed to provide actionable intelligence to mitigate potential threats by analyzing the available cybersecurity data. Existing frameworks, such as MITRE ATT&CK, provide timely mitigation strategies against attacker capabilities yet do not account for hacker data when developing cyber threat intelligence. Therefore, we developed a novel information technology artifact, ATT&CK-Link, which incorporates a novel transformer and multi-teacher knowledge distillation design, to link hacker threats to this broadly used framework. Here, we illustrated how hospital systems can use this framework to proactively protect their cyberinfrastructure against hacker threats. Our ATT&CK-Link framework has practical implications for cybersecurity professionals, who can implement our framework to generate strategic, operational, and tactical cyber threat intelligence. ATT&CK-Link also contributes to the information systems knowledge base by providing design principles to pursue targeted cybersecurity analytics, risk management, and broader text analytics research through simultaneous multi-modal (e.g., text and code) distillation and classification.National Science Foundation18 month embargo; first published 19 February 2024This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Visualization of Bipartite Graphs in Limited Window Size

Bipartite graphs are commonly used to visualize objects and their features. An object may possess several features and several objects may share a common feature. The standard visualization of bipartite graphs, with objects and features on two (say horizontal) parallel lines at integer coordinates and edges drawn as line segments, can often be difficult to work with. A common task in visualization of such graphs is to consider one object and all its features. This naturally defines a drawing window, defined as the smallest interval that contains the x-coordinates of the object and all its features. We show that if both objects and features can be reordered, minimizing the average window size is NP-hard. However, if the features are fixed, then we provide an efficient polynomial time algorithm for arranging the objects, so as to minimize the average window size. Finally, we introduce a different way of visualizing the bipartite graph, by placing the nodes of the two parts on two concentric circles. For this setting we also show NP-hardness for the general case and a polynomial time algorithm when the features are fixed.12 month embargo; first published 07 February 2024This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Organophotocatalytic Deuteration of α-Amino/Oxy C-H Bonds via H/D Exchange With D2O

In the past decade, photoredox catalysis and photoinduced HAT (hydrogen atom transfer) catalysis have undergone substantial development and come to the forefront of organic chemistry. Recently, photoinduced hydrogen isotope exchange (HIE) reactions have emerged as a viable strategy for deuteration reaction. HIE reactions allow a late-stage incorporation of hydrogen isotopes in a single synthetic step, thus representing an advantageous alternative to conventional multistep synthesis approaches which are time- and resource-consuming. The development of novel photoinduced HIE reactions, especially those difficult to achieve by other means, could make a significant impact on streamlined synthesis, molecular modification and drug discovery. The aim of our study detailed in this thesis is to develop photoinduced strategies for selective deuteration of hydridic C-H bonds. By leveraging the advantages of photoredox and HAT catalysis, these synthetic methodologies would offer efficient and green approaches to the synthesis of valuable chemicals as well as the late-stage functionalization of pharmacophores and natural products. We hope our study could inspire more aspects of organic synthesis in a green manner.In the first effort, we developed a straightforward H/D exchange method for the synthesis of α-deuterated primary amines from a diverse set of primary amines with high levels of deuteration and chemo- and site selectivity and preparative utility. This cost-effective strategy enables the direct conversion of primary amines to α-deuterated counterparts using D2O as the deuterium source under mild reaction conditions without requiring additional functionality manipulation and with minimal byproduct production. In the second effort, a mild metal- and oxidant-free visible-light photoredox mediated selective deuteration of α-C-H bonds of secondary alcohols, masked secondary amines and secondary amides via H/D exchange with D2O is developed. The prevalence of “O” and “N” adjacent metabolically labile C-H bonds in pharmaceuticals demands the efficient methods for replacement by deuterium. However, selective deuteration of these C-H bonds has been challenged by ubiquitous C-H bonds and the structural diversity of these heteroatom associated functional groups. We have developed a mild organophotoredox and hydrogen atom transfer co-promoted H/D exchange strategy for selective deuteration of secondary alcohols using D2O as deuterium source with high level of deuterium incorporation (up to 100%). Furthermore, through temporary masking secondary amines with Boc group, excellent and highly regio-selective deuteration can be achieved with the catalytic system. We also expended the strategy for the unprecedented deuteration of secondary amides highly efficiently.Release after 07/31/202

Solution path algorithm for distributionally robust regression

In this paper, we propose a general distributionally robust regression model based on distributionally robust optimization theory. The proposed model has a piecewise linear loss function and elastic net penalty term, and it generalizes many other regression models. We prove the piecewise linear property of the optimal solutions to this model, which enables us to develop a solution path algorithm for the hyperparameter tuning. A Doubly regularized Least Absolute Deviations (DrLAD) regression model is proposed based on this framework, and a solution path algorithm is developed to speed up the tuning of two hyperparameters in this model. Numerical experiments are implemented to validate the performance of this model and the computational efficiency of the solution path algorithm.12 month embargo; first published 22 April 2024This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Development of Novel Polymeric Sunscreens

This dissertation details the preparations and investigations of novel polymeric sunscreen agents as alternatives to commercial chemical and mineral sunscreens. In addition, results obtained from an investigation into the efficacy and photostability of North American commercial sunscreens are also reported. Based on the discoveries made during the research studies, two new classes of polymeric sunscreen agents with excellent broad-spectrum photoprotections and photostabilities are reported. The first chapter is a comprehensive review discussing the classifications of sunscreen agents, their photoprotective mechanisms, benefits, limitations, safety concerns, cosmetic additives utilized in the manufacturing process, as well as the types of formulations used during product development. Methods developed and regulatory requirements for evaluating the broad-spectrum efficacy of sunscreen agents, their photostability, and immunosuppression protection were also discussed. This chapter provides the context necessary for understanding commercial sunscreens investigated in chapter two and the in vitro broad-spectrum photoprotective efficacy evaluations conducted in chapters two, four, and five. In Chapter 2, the findings of a research study investigating the UV photostability and efficacy of 20 commercial sunscreens with SPF 50 labels are reported. The commercial sunscreens involved 10 chemical and 10 mineral non-prescription sunscreens currently available on the North American market. The UVB and UVA efficacy changes were evaluated using in vitro methods as a function of UV exposure using simulated sunlight. A research study investigating the efficacy of commercial sunscreens at this scale had not been conducted for the North American region prior to the author’s study, making it unique. Chapter 3 is an up-to-date comprehensive review summarizing and evaluating the academic publications and invention disclosures related to polymeric sunscreen research. This chapter educates the reader on the advancements made in the field of polymeric sunscreens. It supplies the required context for understanding the novel macromolecular sunscreen materials developed and investigated in chapters four and five. Polymeric sunscreens were categorized as natural biopolymer-based or synthetic polymer-based on their derived source, and their preparation, formulation, and assessment of broad-spectrum photoprotective efficacy and UV stability were summarized and critiqued. The advantages of using polymeric photoprotective agents over existing commercial chemical and mineral sunscreens were also discussed. The author also analyzed biocompatibility, environmental impacts, and commercial implementation costs of these photoprotective macromolecules for value-added applications. Chapter 4 reports on the development of a new class of polymeric sunscreen agents comprised of phenolic-higher aldehyde thermoset resin spheres synthesized using a base-catalyzed polycondensation technique under hydrothermal conditions. These thermoset resin-based sunscreens are water-resistant, absorb and scatter broad-spectrum UV radiation, provide excellent UV skin protection, and have enhanced stability to UV-induced photodegradation. The photodegradation effects of phenolic-aldehyde thermoset resins were evaluated using IR spectroscopy and SEM techniques, and photodegradation mechanisms were discussed. Chapter 5 disclosed novel antioxidant, broad-spectrum polymeric sunscreens synthesized by post-polymerization click modification of polybutadienes with three distinct s-tetrazines. The polydihydropyridazines synthesized using click modifications were hydrophobic, antioxidant, provided excellent broad-spectrum UV protection, and were fluorescent active. Quenching of fluorescence was seen with chemical or photooxidation of polydihydropyridazines to polypyridazines, along with a loss of antioxidant activity and photoprotective effect. Loss of fluorescence activity provides a visual tool for qualitative monitoring of the extent of photooxidation of polydihydropyridazine sunscreen polymers. Photooxidative degradation of polydihydropyridazine thin films exposed to UV radiation was monitored using 1H NMR and IR spectroscopy. The antioxidant activity of polydihydropyridazines was evaluated using cyclic voltammetry. Finally, Chapter 6 summarizes the research conducted in chapters two, four, and five and provides future research ideas to address the shortcomings of current work.Release after 05/01/202

Marsscapes to Terrestrial Moonscapes: A Variety of Water Problems

This dissertation is composed of nine papers that are divided into sections on: 1. Mars (four papers); 2. Land-management implications of terrestrial climate change (three papers); and 3. Methods of postfire hydrologic analysis (two papers). In the Mars section, three articles use spacecraft data to address the question of an ancient paleoocean in the northern plains along with the evolution of the Tharsis Superplume and Valles Marineris. The final one is an overview of the niches which, based upon terrestrial analogues, may have been hospitable for life. The studies that addressed practical, climate-change-related land management challenges included one each on spring discharge of a fractured basaltic aquifer that is critical for both water supply and energy production in California, which forestry treatments retain the most moisture on the landscape, and how a sensitive salamander responds to fuel-reduction activities in a drying climate. The final section contains two interconnected, pedagogical articles. The first one makes the point that satellite-based remote sensing of postfire vegetation burn severity is inapt for hydrologic analyses. Instead, the appropriate metric is soil burn severity. We developed the sequel for the US Forest Service’s Burned Area Emergency Response (BAER) Program as a manual on postfire hydrologic modeling. Rather than being a tutorial on specific software, it seeks to explain how to think like a modeler, appreciate model limitations and uncertainty, and communicate predictions to the public in such a way that they understand a) how wrong and b) how useful the numbers are

Decoding the gene regulatory network of endosperm differentiation in maize

The persistent cereal endosperm constitutes the majority of the grain volume. Dissecting the gene regulatory network underlying cereal endosperm development will facilitate yield and quality improvement of cereal crops. Here, we use single-cell transcriptomics to analyze the developing maize (Zea mays) endosperm during cell differentiation. After obtaining transcriptomic data from 17,022 single cells, we identify 12 cell clusters corresponding to five endosperm cell types and revealing complex transcriptional heterogeneity. We delineate the temporal gene-expression pattern from 6 to 7 days after pollination. We profile the genomic DNA-binding sites of 161 transcription factors differentially expressed between cell clusters and constructed a gene regulatory network by combining the single-cell transcriptomic data with the direct DNA-binding profiles, identifying 181 regulons containing genes encoding transcription factors along with their high-confidence targets, Furthermore, we map the regulons to endosperm cell clusters, identify cell-cluster-specific essential regulators, and experimentally validated three predicted key regulators. This study provides a framework for understanding cereal endosperm development and function at single-cell resolution. © 2024, The Author(s).Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Why the Sidewalk Ends: Analysis of Sidewalk Infrastructure in Tucson, Arizona

Sustainable Built Environments Senior Capstone ProjectInequitable sidewalk infrastructure perpetuates social inequalities. Furthermore, good sidewalk infrastructure has many health, social, and environmental benefits. To study the inequitable sidewalk infrastructure in Tucson, I did a case study analysis of two neighborhoods of different socio-economic status. The neighborhood with higher income levels had more and better sidewalks. I conducted interviews with neighborhood representatives and the city of Tucson professionals to understand why this was. I found that the main issues with current sidewalk development were that the funding sources are problematic and the responsibility for sidewalk development often ended up on the property owners or developers. To remedy these issues, I propose a new funding source, a development tax, and a city-run program to target areas in the greatest need of sidewalk infrastructure.This item is part of the Sustainable Built Environments collection. For more information, contact http://sbe.arizona.edu