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Study of the Physics and Detectability of Compact Black Hole Binaries using Multi-messenger Observations
No full textThis dissertation investigates the detectability and multimessenger signatures of two types of black hole binaries: compact supermassive black hole binaries (SMBHBs) driven by gravitational wave radiation, and the tidal disruptions of a star by a stellar-mass black hole (sBH) in close and low-eccentricity encounters.
In this dissertation, we first discuss the detectability of compact SMBHBs in time-domain surveys as periodic quasars, and in gravitational wave (GW) missions as low-frequency GWs. Using a series of analytical and statistical approaches, we estimate that up to ∼ 100 million quasars can be observed by the upcoming Legacy Survey of Space and Time (LSST), among which a small fraction can be associated with compact SMBHBs driven by GW-inspiral. We then demonstrate once their GWs are detected by the Laser Interferometer Space Atenna (scheduled to launch in mid-2030s), then their EM counterparts can be uniquely identified in LSST using the historical frequency evolution and other key information from GWs. Finally, we show that chirping compact SMBHBs are identifiable using a Bayesian method on their EM lightcurves alone.
We then investigate the close and low-eccentricity encounters between sBHs and stars, causing tidal disruption events; an interaction frequently expected in dense star clusters and the disks of active galactic nuclei. We perform a suite of hydrodynamical simulations of tidal disruption of a main-sequence star by a sBH. We study a range of binary mass ratios, semi-major axes and eccentricities. We demonstrate that under certain circumstances, the mass of the star is slowly stripped away by the sBH – we dub this a “tidal-peeling event” (TPE). We discover that some TPEs can be a new form of luminous galactic transients; TPEs exhibit significant accretion rates that can sometimes lead to semi-periodic luminosity fluctuations and powerful outflows
Determining the impact of the interval between repetitive low-level blast exposures on functional deficits in the hippocampus
No full textTraumatic brain injury (TBI) is a significant cause of death and disability worldwide. Although mTBI (mTBI) accounts for the majority of TBIs, frequent underdiagnosis increases the likelihood of repeated injuries. TBI has also been a major concern for the United States military over the past decade. Previous research largely focused on moderate and mild blast TBIs (bTBIs) that modeled shock waves from improved explosive devices (IEDs), but there is growing concern that repeated exposure to shock waves of lower intensities also may be capable of inflicting neurocognitive deficits. Concern is particularly relevant during training exercises where large numbers of trainees, and particularly trainers, may experience repeated exposures. Current training protocols impose a 4 psi (28 kPa) limit on individual overpressure exposures but fail to account for the cumulative and temporal dynamics of repetitive low-level blast exposures. To improve such guidelines, we must better understand how repetitive low-level blasts over time lead to neurocognitive deficits. In this thesis, we modified our existing shock tube apparatus to develop a new Level 0 blast exposure representative of firing heavy weapons. This dissertation investigated how the number of blasts, inter-blast interval (IBI), and number of sessions interact to influence the neurophysiological and molecular consequences of repetitive low-level blast.
In Aim 1, we utilized this new Level 0 blast exposure to develop tolerance criteria for repetitive low-level blasts with a 5 min IBI. We observed that repetitive low-level blast exposure had a dose-response effect on long-term potentiation (LTP), the cellular correlate for learning, with 3 blast exposures resulting in significant LTP deficits at 24 h after blast. Overall, LTP deficits spontaneously recovered between 48 and 72 h after blast. Increasing the IBI to 1 or 2 days largely attenuated LTP deficits.
In Aim 2, we investigated the molecular mechanisms of blast-induced LTP deficits. Although evoked stimulus-response parameters were unaltered by blast, spontaneous network characteristics, including spike duration, spike amplitude, and connectivity coefficient, were elevated in a delayed manner. Expression of the anti-inflammatory cytokine interleukin-10 (IL-10) exhibited a biphasic pattern after blast exposure, characterized by initial suppression at 3 h after blast followed by overexpression 24 h after blast. Treatment with progesterone, a potent anti-inflammatory agent, both attenuated LTP deficits and increased early IL-10 expression to prevent the delayed overexpression of IL-10. Blast also induced a minor deficit in the synaptic protein postsynaptic density protein 95 (PSD-95) and slight increases in expression of inflammatory markers.
In Aim 3, we increased blast quantity, varied same-day IBIs, and introduced multiple sessions of repetitive blast to better understand how the complex interplay of these parameters drives mechanisms of blast-induced LTP deficits. Surprisingly, a single session of 6 blast exposures with a 1 h IBI produced significantly greater LTP deficits than when delivered with a shorter 30 min IBI. This phenomenon persisted when the 6 blasts were instead split over 2 sessions of triple blast. Both IBI and number of sessions affected the expression of synaptic proteins and inflammatory proteins in a nonlinear fashion that did not consistently correlate with LTP outcomes.
Overall, this dissertation has demonstrated that repetitive low-level blasts with same-day IBIs can significantly impair synaptic plasticity depending on the timing of blast exposures. These findings have provided foundational data to expand upon the tolerance criteria for repetitive blast exposures by improving our understanding of how the number of blasts, IBI, and number of sessions drive blast-induced molecular mechanisms of injury. Ultimately, the insights from these studies can inform the development of safer training protocols to establish occupational exposure limits designed to prevent neurological impairments and long-term health consequences
Assessing disparities in access, use, and potential benefits of weather and climate information services among farmers in Guatemala’s Dry Corridor
No full textClimate risk is a critical challenge for smallholder farmers in Guatemala, and weather and climate information services (WCIS) are a growing policy solution. Using a survey of 330 farming households in Guatemala’s Dry Corridor, this research examines farmers’ ability to access and utilize WCIS for agricultural decision-making, as well as the association between WCIS and food insecurity. Our observational study found that while reported access to one approach, Local Technical Agro-Climatic Committees (LTACs) and agro-climatic bulletins (ACBs), was lower than expected among a representative sample of communities, nearly half of respondents reported accessing weather and climate information more generally. In an observational comparison, those accessing information implemented significantly more climate-resilient agricultural practices and were significantly more food secure than those not receiving the information; however, accessing information was correlated with household wealth and education, and its effect on food insecurity was not statistically identifiable in a multiple regression test with controls. Our study also provides empirical evidence that a lack of information is not the primary barrier to the adoption of adaptation practices. While farmers expressed a desire to adapt certain farming practices in response to climate risk, they faced financial and other barriers to implementing these strategies. Thus, while WCIS have potential for informing agricultural decisions, this study underscores the challenges associated with effectively delivering information to farmers, as well as highlights obstacles to their use when farmers do receive them. These insights are crucial for refining WCIS design and delivery. Recommendations include investing in more farmer-centric communication channels and coupling information with resources to strengthen farmers’ adaptive capacity
Persian Letters: Language, Politics and Desire in the Late Ottoman Empire
No full textThis dissertation is an intellectual and cultural history which examines how the Persian language, and the notion of Persianate cultural influence upon Ottoman Turkish language and literature, was conceptualized by Ottoman intellectuals, authors, and artists of the late nineteenth and early twentieth centuries. It traces the development of several terms of Ottoman Turkish discourse — among them, “Persianate exaggeration” [mübalağa-ı Acemâne], “Persianate fantasy” [hayâlât-ı Acemâne], and “Persophilia” [Acemperestlik] — and examines the radical experiments in linguistics, literary aesthetics, and the imagination of the desiring subject that these terms engendered. Through a close study of three key figures of the late Ottoman period — the revolutionary poet, journalist and statesman Namık Kemal (1840–1888), the author and soldier Ömer Seyfettin (1884–1920), and the cabaret performer Peruz Terzakyan (c. 1866–1919) — it argues that the conflation of the Persianate with nonsense, fantasy, and fatalistic enjoyment was foundational to the articulation of a Turkish literary and linguistic modernity autonomous from the deprecated “Persianized” [Acemleşmiş] Ottoman past, with legacies that have persisted through the comprehensive sociolinguistic reforms of the subsequent Turkish Republic.
This dissertation is divided into three sections. The first examines the writings of expatriateor exilic Iranian intellectuals in nineteenth-century Istanbul in connection with Ottoman and Turkish writers and artists of the same period, and follows their debates on script, language, and literary style in the context of comparative linguistics and the racialization of language. It focuses in particular on the epistolary encounter of the Iranian reformist intellectual Mirza Malkum Khān (1834–1908) and Namık Kemal, and argues that through these engagements the Ottoman Persianate increasingly was defined by the elevation of fantasy over reality, wordplay over meaning, and gendered tyranny over freedom.
Sections two and three examine how this notion of the Persianate structured the later linguistic projects of Ömer Seyfettin and Peruz Terzakyan, as case studies of this discourse in its most extreme forms: the first, a proposal for a definitive break in both language, literature, and modes of desire, and the second an experiment in radical estrangement, exploding language beyond the limits of sense. It concludes by exploring the movement of the Persianate from high literary culture during the Ottoman era into a marker of marginalized subjectivity and queered nonsense in the contemporary Turkish Republic
"Database Demo" Library Workshop Materials
No full textThe materials included in this resource are meant to accompany the Columbia University Library workshop "Database Demo." Some information and screenshots included have been sourced from other materials created by Columbia University Library staff.
This resource was developed as part of the Ask a Librarian Internship Program, which provides currently-enrolled library and information science students with hands-on experience in academic librarianship
Black Science Teacher Attrition as Political Struggle in the United States during the post-Obama Era of 2017-2022
No full textThe five-year period following the 44th presidency of Barack Obama has been marked by increased anti-Black violence, neoliberal capitalism, and U.S. imperialism and the continued deterioration of the social and political working conditions of the Black masses. In the years following the Department of Education arguably continues to fail to retain an adequate number of Black science teachers in the growing need for equitable and accessible public science education.
This study collects and interprets the narrative-biographies of Black former science teachers by exploring their political experiences through storytelling of their life histories, educational experiences, and professional development before, during, and after leaving the classroom since the academic year of 2017-18, characterized here as the post-Obama era. Interviews and their transcriptions were analyzed using an anti-oppressive research methodology of self-thematization alongside a hermeneutic of a-priori codes that reflected political consciousness, identity, and activity in Black former science teacher’s decision-making throughout their teaching career that may have led to their early retirement.
Through a critical Marxist perspective of historical materialism and antiblackness in science education, the resulting narrative-biographies add to the expanding literature of science teacher attrition and Black political resistance in the United States
The Cost of Capital: Lowering the Cost of Capital for Climate and SDG Finance in Emerging Markets and Developing Economies
No full textToday, some of the world's fastest-growing economies face some of the highest borrowing costs—even for clean energy and development projects with strong fundamentals. This is not a function of global capital scarcity. Trillions are available. The problem lies in systemic barriers that prevent capital from flowing to where it’s most urgently needed. The high cost of capital in EMDEs not only undermines critical financing for the energy transition and sustainable development; it also limits the ability for US- and EU-based financial institutions to invest in and finance projects in EMDEs, despite institutional and stakeholder appetite and interest for transition finance.
This paper provides a holistic diagnosis of the structural forces inflating the cost of capital in EMDEs—including sovereign credit ratings, investor risk perceptions, development finance mandates, and regulatory norms – and it outlines ten actionable solutions to unlock long-term, affordable finance for climate and sustainable development—at the speed and scale required by both global goals and national ambitions
Building Resilient Relationships
No full textThis Viewpoint advocates for a targeting therapeutic intervention for the amelioration of loneliness and related mental health problems
Extracting Social Support and Social Isolation Information from Clinical Psychiatry Notes: Comparing a Rule-based NLP System and a Large Language Model
No full textObjectives
Social support (SS) and social isolation (SI) are social determinants of health (SDOH) associated with psychiatric outcomes. In electronic health records (EHRs), individual-level SS/SI is typically documented in narrative clinical notes rather than as structured coded data. Natural language processing (NLP) algorithms can automate the otherwise labor-intensive process of extraction of such information.
Materials and Methods
Psychiatric encounter notes from Mount Sinai Health System (MSHS, n = 300) and Weill Cornell Medicine (WCM, n = 225) were annotated to create a gold-standard corpus. A rule-based system (RBS) involving lexicons and a large language model (LLM) using FLAN-T5-XL were developed to identify mentions of SS and SI and their subcategories (eg, social network, instrumental support, and loneliness).
Results
For extracting SS/SI, the RBS obtained higher macroaveraged F1-scores than the LLM at both MSHS (0.89 versus 0.65) and WCM (0.85 versus 0.82). For extracting the subcategories, the RBS also outperformed the LLM at both MSHS (0.90 versus 0.62) and WCM (0.82 versus 0.81).
Discussion and Conclusion
Unexpectedly, the RBS outperformed the LLMs across all metrics. An intensive review demonstrates that this finding is due to the divergent approach taken by the RBS and LLM. The RBS was designed and refined to follow the same specific rules as the gold-standard annotations. Conversely, the LLM was more inclusive with categorization and conformed to common English-language understanding. Both approaches offer advantages, although additional replication studies are warranted
Ambient Empire: Ecologies, Colonies, and Nature Vivante in Modern Paris, 1860–1940
No full textThis dissertation is an art, architecture, and media history of greenhouses, aquariums, and colonial gardens in Paris (c. 1860–1940). Many of these spectacular sites were constructed at Exposition Universelles, world’s fairs that showcased imperial projects and new technologies. Because these simulated environments featured living beings, they required vast imperial networks and complex technological supports in order to keep animals and plants alive as they moved around the globe.
Consequently, this dissertation narrates the rise of a biopolitics of the nonhuman—a transformation across the French empire that impacted architectural forms and their infrastructures as well as other art and media that similarly tried to capture, sustain, and convey living ecosystems.
I focus on the enormous influence of nonhuman life and infrastructural ecologies on modern spectacles in Paris through documentary evidence of these built sites alongside the modernist artworks of impressionist painters, early filmmakers, and surrealists who visited these popular attractions and interrogated their ideologies and effects. In particular, I examine James Tissot’s paintings of greenhouses, Georges Méliès’s films using aquariums, and Man Ray’s suite of photographs of colonial gardens alongside other modern media with which these artists interacted, including museums, Orientalist painting, ethnographic photography, human zoos, science fiction novels, film studios, and travel magazines.
Greenhouses, aquariums, and colonial gardens were sites of state propaganda. They guided visitors to think about race, technology, and empire, teaching lessons about the state’s biopolitical power over plant and fish specimens (and, by extension, their colonial equivalents) as well as the increasing artificiality of nature in the age of industrial empire. Each chapter also identifies one major modernist idea—atmosphere, infrastructure, and hybridity, respectively—that was foregrounded within these immersive environments and then debated across diverse fields, showing how art, science, and colonial policy interacted in Paris and overseas