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Combining Sources and Leveraging Contexts
Get PDFIn this thesis we discuss two levels of knowledge beyond regression and classification. The first involves the identification of exchangeable scenarios or individuals from which causal relationships can be ascertained. We discuss one key difficulty of this task, the "Multi-Source Conundrum," which emerges whenever data is merged from multiple sources. This motivates the "Principle of Limited Latent Classes," an assumption which allows us to introduce new algorithms for deconfounding and causal structure learning.
The second level of knowledge involves the expansion from contextual exchangeability to contextual synthesis. We will study a paradox of nontransitivity that occurs when combining multiple contexts, as well a demonstrating robustness gains from using context-dependent counterfactuals as training features. Through these points, we present contextual synthesis as a new frontier with promise for advances in out-of-distribution robustness, fairness, and privacy.</p
Cosmic Gold Mining: Hunting for the Astrophysical Sites of r-Process Nucleosynthesis
Get PDFOne of the major open questions in astronomy is where the heaviest elements in the Universe are formed. These elements, generated via the rapid neutron-capture process (r-process), require environments abundant with free neutrons, present only in extreme cosmic explosions, which are by nature inherently rare. To date, vivid, direct evidence of heavy element nucleosynthesis has been seen and most extensively studied in the binary neutron star (BNS) merger GW170817. However, neutron star–black hole (NSBH) mergers, some collapsing massive stars (collapsars), and other explosions have also been proposed as alternative sites of r-process production. This thesis explores BNS mergers, NSBH mergers, and collapsars as r-process sites through observational studies. In this work, we first investigate whether r-process signatures are present in the light curves of broadlined type Ic supernovae (SNe Ic-BL) associated with long-duration gamma-ray bursts. For this study, we conduct optical imaging with the Zwicky Transient Facility (ZTF) and near-infrared imaging with the Wide-Field Infrared Camera on the Palomar 200-in Hale telescope of ZTF-discovered SNe Ic-BL. Second, we study the chemical distribution of ejecta in the kilonova (KN)---an optical/near-infrared transient powered by the radioactive decay of r-process elements---counterpart to GW170817, using new state-of-the-art KN models and incorporating precise inclination information on GW170817 into our inference. Third, we describe systematic searches conducted with ZTF for KNe associated with both BNS and NSBH mergers detected by the LIGO Virgo KAGRA detector network during its third and fourth observing runs. Based on our non-detections, we place constraints on the properties of KNe from both BNS and NSBH merger sites. Finally, we summarize the unique insights we have gained on the nature of r-process sites from observations and non-detections. We also discuss prospects for discovering and characterizing these transients with upcoming surveys such as the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope
Beowulf and the Moral Dilemma Between Kingship and Heroism
No full text[Introduction] While Beowulf is largely a poem chronicling the exploits of the titular hero, one of the integral roles in Beowulf is that of the king. From the very exposition of the poem, the reader is introduced to the kings of the Danes and their respective lineages, implicitly highlighting the role of the kings in shaping the story. The poem describes a variety of kings, both “good” and ‘bad’, but what is especially interesting to note is the use of kings as both a complement and a contrast to heroes. The values and responsibilities of the king seem to differ vastly from that of a hero, with the exception of the titular character Beowulf himself. Despite ascending the throne and serving as a “good king” (2390) “for fifty years” (2733), Beowulf still seems to toe the line between serving as a king and serving as a hero, which makes him a prime candidate while analysing the moral code of kings and heroes in the poem Beowulf. This essay aims to explore how the expectations from kings and heroes contrast each other in Beowulf, and how Beowulf himself seems to be unwilling to transition between the two states
The Paradox of Authentic Happiness and Existential Suffering
No full text[Introduction] Is the apparent connection between happiness and authenticity as straightforward as it seems? Intuitively, if we are ‘true to ourselves’ or, colloquially, if we ‘follow what our heart desires’, we should experience more positive feelings, or ‘happiness’. However, why does existentialism often invoke negative feelings like suffering and despair when a big part of it focuses on being ‘true to ourselves’? Why is there such an incompatibility between happiness and existentialism? To explore this paradox, I will briefly review the discord between authenticity and existential suffering. I then argue that current scholarship on well-being and happiness does not satisfactorily address this perceived incompatibility. I will do so by demonstrating that widely accepted normative theories of subjective well-being—particularly those steeped in the pursuit of hedonistic pleasures—are potentially emblematic of projects of bad faith. Counter-intuitively, I posit that the existentialist can attain happiness by demonstrating proportionality between the experience of suffering and the experience of being authentic. I will also substantiate this by showing how components of existential concepts, including suffering as a catalyst and self-concordance, significantly influence well-being
Dear Goose
No full text[Introduction] Dear Goose, I am hesitant to write to you. Because I know you don’t like to read. Because I know English is hard. I am writing to thank you, to apologize to you, and to get to know you. I am told that is important
Open-Source Custom Beads for Single-Cell Transcriptomics
Get PDFOpen-source single-cell genomics technologies have helped democratize single-cell genomics and expedite method development. Methods such as inDrops and Drop-seq for single-cell RNA-seq preceded popular technologies such as the 10x Genomics’ Chromium platform, however despite initial enthusiasm for open-source methods, their popularity has waned. A major reason has been the lack of availability of low-cost, customizable beads, which are essential for microfluidics based single-cell RNA-seq. We address this challenge by introducing a new method for producing barcoded hydrogel beads for single-cell RNA-seq called HiPER (High-throughput PER-barcoded hydrogel beads) that allows for increasing the diversity of barcode sequences, reducing manufacturing cost, and that can be readily adapted to custom applications. HiPER barcodes are decoupled from the capture sequences and can therefore be configured to capture RNA, DNA, or tailored for specific-gene enrichment
Physics and Applications of Optical Nonlinearity in High-Q Microresonators
Get PDFOptical microresonators trap light in compact volumes at discrete resonant frequencies. Benefiting from the ultra-low propagation loss, the electromagnetic wave intensity is greatly enhanced. Due to the pronounced light confinement, nonlinear optical effects are significantly magnified in the microresonators. In this thesis, I investigate various nonlinear optical phenomena using high quality factor silica wedge and fully-integrated thin film silicon nitride microresonators. The exploration begins with Kerr nonlinearity-induced soliton microcombs followed by their application in mid-IR band gas spectroscopy. The generation of solitons under normal dispersion conditions, which frustrate soliton formation, is then considered. Subsequently, attention is directed towards stimulated Brillouin lasers and their frequency noise performance, including long-term frequency stabilization based on the built-in temperature reference and validation of two modification factors affecting short-term fundamental linewidth. Along this journey, a novel method for calibrating ultra-narrow laser linewidths is introduced. Lastly, this method is employed to measure the narrow linewidth of a visible laser generated through second harmonic generation in silicon nitride resonators
Electronic Skin in Robotics and Healthcare: Towards Multimodal Sensing and Intelligent Analysis
Get PDFSkin-interfaced electronics is gradually transforming robotic and medical fields by enabling noninvasive and continuous monitoring of physiological and biochemical information. Despite their promise, current wearable technologies face challenges in several disciplines: Physical sensors are prone to motion-induced noise and lack the capability for effective disease detection, while existing wearable biochemical sensors suffer from operational instability in biofluids, limiting their practicality. Conventional electronic skin contains only a limited category of sensors that are not sufficient for practical applications, and conventional data processing methods for these wearables necessitate manual intervention to filter noise and decipher health-related information.
This thesis presents advances in electronic skin within robotics and healthcare, emphasizing multimodal sensing and data analysis through machine intelligence. Chapter 1 introduces the concept of electronic skin, outlining the emerging sensor technologies and a general machine learning pipeline for data processing. Chapter 2 details the development of multimodal physiological and biochemical sensors that enable long-term continuous monitoring with high sensitivity and stability. Chapter 3 explores the application of integrated electronic skin in robotics, prosthetics, and human machine interactions. Chapter 4 showcases practical implementations of integrated electronic skin with robust sensors for wound monitoring and treatment. Chapter 5 highlights the transformative deployment of artificial intelligence in deconvoluting health profiles on mental health. The last chapter, Chapter 6, delves into the challenges and prospects of artificial intelligence-powered electronic skins, offering predictions for the evolution of smart electronic skins. We envision that multimodal sensing and machine intelligence in electronic skin could significantly advance the field of human machine interactions and personalized healthcare.</p
Search for New Physics with the Compact Muon Solenoid Experiment and QIS-enabled Technology
Get PDFUnderstanding the fundamental nature of dark matter (DM) — its cosmological origin, constituents, and interactions — is one of the most important questions in fundamental science today. In this thesis, I present two novel and highly complementary approaches to cover the gaps in sensitivity of current DM searches. The searches are enabled by a first-of-its-kind reconstruction technique to search for hidden-sector particles using the Compact Muon Solenoid (CMS) and by new advances in quantum sensing technology to search for axions and hidden-sector DM.
In the first part of this thesis, I present a search for long-lived hidden sector particles, predicted by many extensions of the SM, using a novel technique to reconstruct decays of long-lived particles (LLPs) in the CMS muon detector. The innovative LLP reconstruction technique is sensitive to a broad range of LLP decays and to LLP masses below GeV. The search yields competitive sensitivity for proper lifetime 0.1 - 1000 m with the full Run 2 dataset recorded at the LHC between 2016 - 2018 at √s = 13 TeV. To extend the physics reach of this novel muon detector shower (MDS) signature, I present the model-independence of MDS and the reinterpretation of the search to a large number of LLP models, demonstrating its complementarity with proposed and existing dedicated LLP experiments. Finally, I present a new dedicated MDS trigger that improves the trigger efficiency by at least an order of magnitude and was deployed in 2022, at the start of Run 3 of the LHC operations.
In the second part of the thesis, I present for the first time, the use of a novel quantum sensor, the low-noise and single-photon sensitive superconducting nanowire single photon detectors (SNSPDs), to directly detect dark matter. The low detection threshold and ultra-low dark count rate of SNSPDs can close the gap in DM discovery reach due to the current limitations in detector sensitivity. I will present my work on the development and characterization of SNSPDs for two entirely new experiments to directly detect axions via absorption and hidden-sector DM via electron scattering. The search for axions employs a novel broadband reflector technique with the Broadband Reflector Experiment for Axion Detection (BREAD). A unique parabolic mirror is then used to focus axion-converted photons to the SNSPDs, extending the reach to axion masses of 0.04 - 1 eV. On the other hand, by coupling the SNSPDs with gallium arsenide, a bright cryogenic scintillator well matched to SNSPD detection, a prototype sensing system can be built as a basis of new direct DM detection experiments capable of extending the discovery to DM masses as low as 1 MeV.</p
Thinking Queerness and Forming Intimacies: Understanding Identity, Relationships, and Queerness in South Asian Diasporic Contemporary Literature, 1981–2022
Get PDFReading intimacy in South Asian diasporic texts requires a nuanced framework to understand the impersonality of sex, and blurrings within relationships and intimacies. Intimacy, both emotional and physical, depends on vulnerability to connect with others. I use a queer diasporic framework to analyze a selection of scenes from different contemporary South Asian diasporic texts, from 1981–2022. Specifically, I analyze their portrayals of intimacy and relationships to disrupt binaries invoked on how we might view intimacy. Such a framework also affords insights into how the diaspora and queerness both influence identity and disrupt heterosexual readings of texts to allow for deeper emotional intimacies. The framework is grounded in queer theory, history of the LGBTQ+ community and the queer body, and history of the diaspora to allow for nuanced readings of the texts. Through exploring the queer diaspora in these contemporary texts, I challenge binaries of both the queer and diasporic frameworks in ways that encompass the complexities of the relationships we find ourselves in