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Building Communities of Upward Mobility
No full textAround 3.5 billion people, 44 percent of the global population, remain poor (below
$6.85 per day) (World Bank, 2022). Alleviaitng poverty requires finding ways of
upward mobility. I study 3 such ways.
The first and main paper in my dissertation found that uniting teachers, parents and
principals around the protection of children's rights is a powerful way of fostering a
loving environment for more than 200 000 children from low-income backgrounds
to thrive.
The second paper in my dissertation suggests that fostering connections between
high- and low-income individuals is essential for lower-income individuals' upward
mobility, potentially through higher income individuals acting as role models,
information sources, and providers of job referrals to lower income individuals.
The third paper in my dissertation suggests that hiring passionate young graduates
as teachers in shcools in low-income rural areas can give access to a decent
education to low-income children who might not have one otherwise.Economic
Towards the Equitable and Sustainable Transformation of Agrifood Systems: Evidence at the Intersection of Agroecology and Public Health
No full textFood systems — the interconnected ways through which humanity produces, distributes, and consumes food — are culpable for a substantial share of today’s ecological crises, yet they also fail to deliver healthy, affordable food for all or secure decent livelihoods for those who produce it. While numerous solutions have been proposed to mitigate food systems’ disproportionate environmental impacts, most are incremental and neglect intertwined public health and social justice challenges, including persistent food inequities, rising rates of diet-related chronic disease, and mounting economic and climate stress for farmers and food system workers. Agroecology, by contrast, advances the premise that durable reform must be transformative, addressing the underlying social and structural drivers, such as power imbalances and consolidation, that perpetuate environmental degradation, inequities, and human health burdens. This dissertation offers novel insights at the intersection of agroecology and public health, examining how structural forces in U.S. food systems entrench unsustainability and identifying leverage points for transformation that could accelerate agroecological change, with benefits for environmental, social, economic, and public health.
The first study (Chapter 1) examines how structural forces have shaped unsustainable agricultural practices in the U.S. by analyzing the relationship between county-level cropland consolidation and pesticide intensification. Despite the development of higher potency formulations, overall use has remained persistently high, raising planetary health concerns given pesticides’ significant human health and environmental impacts. However, little evidence has addressed how structural factors, such as the substantial consolidation of U.S. farmland and the expansion of average farm size, influence these patterns. Employing longitudinal data from 1,466 non-metro counties (1992–2012), we found that greater cropland consolidation was significantly associated with increased pesticide intensity, with an estimated 37% of this association explained by shifts toward high-pesticide-intensity crops. Stratified models revealed notable regional heterogeneity; positive associations emerged in the Southeast and Corn Belt, while a negative association appeared in Appalachia. Efforts to transition toward agroecological food systems and reduce agricultural inputs may need to address systems-level factors like consolidation through regionally tailored approaches.
The second study (Chapter 2) examines how increasing supply chain opacity, driven in part by structural shifts such as consolidation in the retail food sector, may enable greenwashing — misleading consumers about the true environmental benefits of products. Greenwashing represents a structural barrier to food systems transformation by undermining consumer trust and preventing market signals from effectively supporting agroecological transitions. After developing and psychometrically testing a novel coding instrument, we applied it to more than 23,000 food and non-alcoholic beverage products across two major U.S. online retail platforms. Over 10% of products carried front-of-package environmental claims; of these, nearly two-thirds at the conventional supermarket and one-third at the natural food store were determined to be greenwashed, primarily due to inadequate claim substantiation. Most environmentally marketed products were ultra-processed, the vast majority of claims were executional in nature (i.e., relying on implicit design or visual cues rather than explicit statements), and greenwashing prevalence was highest in the meat and meat alternative categories. Regulating environmental claims in the food sector should be urgently considered as a strategy to both protect consumers and prevent greenwashing from impeding agroecological transitions.
The third study (Chapter 3) explores how farmers’ relational values shape motivation and engagement in agroecological practices. While transforming food systems will require widespread adoption of ecologically and socially sustainable practices, limited U.S. research has examined how farmers' value systems influence both their adoption of on-farm sustainable practices and their participation in broader agroecological change. Interviews with 32 small- and mid-sized Oregon farmers revealed strong relational values — rooted in care for land, animals, and community — that motivated both ecological stewardship and social action, including efforts to improve community food security and well-being. However, farmers’ ability to act on these values was constrained by structural barriers, including economic precarity, policy exclusion, and sociocultural devaluation. Centering farmers’ values in policy and designing strategic supports that enable them to act in alignment with their existing relational values may be critical to accelerating the widespread adoption of agroecological practices and advancing a just, equitable transformation of U.S. food systems.
Together, these three studies illuminate how structural forces have shaped and continue to reinforce unsustainable food systems, while identifying potential levers for advancing agroecological transitions in the U.S. Our findings underscore the importance of addressing social and structural determinants of sustainability and point to actionable pathways for change, including regulating environmental claims, scrutinizing ongoing farmland consolidation, and fostering cross-disciplinary collaboration between public health, environmental health, and agricultural stakeholders. Strengthening inquiry and practice in this area could accelerate the transformation toward food systems that restore ecological balance, promote human health, and foster social equity.Population Health Science
Real–time Wireless Sensing at the Edge for In Situ Multi-Robot Deployment
No full textAutonomous robots are increasingly being deployed in complex, unstructured, and often GPS-denied environments to support critical tasks such as search and rescue, wildlife monitoring, and exploration. In these domains, coordination among multiple robots is essential for improving task efficiency, spatial coverage, and resilience. Achieving effective multi-robot coordination, however, hinges on access to global state information such as relative positions, which is often difficult to obtain when robots operate under communication constraints and must rely on local onboard sensing alone. Visual sensors such as LiDAR and cameras offer a means of local observation, but their utility degrades significantly in the presence of occlusions or poor visibility. To overcome these limitations, wireless signals have emerged as a complementary sensing modality. By leveraging signal phase variations during a robot’s motion, it is possible to emulate a virtual antenna array and estimate bearing directions to signal sources. However, integrating this capability into mobile robotic systems, and extending it to multi-robot coordination tasks, presents several key challenges related to sensing accuracy, algorithmic scalability, platform constraints, and real-world deployment. The central objective of this thesis is to establish wireless signal-based directionality sensing as a robust and scalable onboard modality for coordination in in situ multi-robot tasks, particularly under constrained communication and sensing conditions. To realize this, the thesis makes contributions at the intersection of algorithm design, systems development, and real-world validation. In the first part, we develop a decentralized and distributed coordination algorithms for multi-robot exploration and mapping, relying on bearing estimates derived from signal-phase measurements using commercial off-the-shelf Wi-Fi cards. This approach eliminates the need for a shared map or a global coordinate frame, enabling coordination in GPS-denied and infrastructure-sparse environments. The system is validated under strict communication constraints where robots share only minimal information. In the second part, we extend this capability beyond traditional 2D planar or linear motion to unconstrained 3D free-space motion, allowing aerial robots to perform coordination. We introduce algorithmic and systems-level advances that generalize the bearing estimation process to three-dimensional trajectories and integrate them into a software toolbox deployable on mobile robots with onboard sensing and computation. Finally, we broaden the applicability of this sensing modality by demonstrating compatibility with low-power, off-the-shelf fish tracking tags operating in the very high frequency (VHF) band. These tags are widely used in marine wildlife research to enable remote sensing at long distances. We integrate this capability into a lightweight drone platform and demonstrate real world deployment in challenging marine environments while accounting for stringent size, weight, and power (SWaP) constraints. Overall, this thesis takes a significant step toward making wireless sensing a core primitive for mo- bile robotic systems. It presents novel algorithmic frameworks, open-source system implementations, and extensive empirical validation—both in simulation and in field deployments—that collectively establish wireless-based directionality as a powerful and general-purpose tool for multi-robot coordination in communication-constrained and unstructured environments.Engineering and Applied Sciences - Computer Scienc
The Galactic Halo in Stars and Shadow
No full textThe Galactic halo encodes both the ancient assembly history of the Milky Way and its ongoing interactions with satellites and dark matter. In this dissertation, I present six studies that together develop a new picture of the halo as a tilted, broken, and dynamically complex structure. Using halo stars from the H3 Survey, I show that the inner halo—dominated by the Gaia–Sausage–Enceladus merger—is best described as a tilted triaxial ellipsoid with a doubly broken density profile. I further demonstrate that the halo exhibits strong kinematic asymmetries and that stellar orbits preserve signatures of a misaligned Galactic potential, providing new constraints on the shape and orientation of the surrounding dark matter halo. Through both controlled experiments and cosmological simulations, I establish that tilted halos are long-lived, common in a cosmological context, and naturally excite the Milky Way’s warp and flare, offering a resolution to the decades-old mystery of the Galactic warp. Finally, I explore hypervelocity stars as dynamical probes of the halo’s hidden components. By reconstructing their trajectories, I find that a subset originates not in the Galactic Center but in the Large Magellanic Cloud, providing strong evidence for a massive black hole in our nearest satellite and a new constraint on its past orbit. Together, these results reveal the Milky Way halo as a dynamic structure that records ancient mergers and present-day interactions—traced both in stars and in shadow.Astronom
アルゼンチン・ミレイ政権における厳罰化のレトリックと実際の取組み（論稿）
Get PDFアルゼンチンはほかのラテンアメリカ諸国に比べて治安がよいとされるが、窃盗の増加や麻薬組織の活動により市民の体感不安は高まり、治安改善は重要な政治的課題の1 つになってきた。2023 年に就任したミレイ大統領は、その課題を解決すべく治安政策に注力してきたが、彼が極右と呼ばれるように、その政策アプローチは厳罰化に傾く。このことを受けて、本稿では、ミレイ政権が厳罰化をどのように語り、どのように取り組んできたかを明らかにする。第1 に、ミレイ大統領による厳罰化のレトリックには、厳罰化の方針を掲げるだけでなく、彼の野党批判や自由市場経済を重んじる政策姿勢が反映されており、厳罰化の必要性が多面的に語られている。第2 に、レトリックにとどまることなく、軍の国内治安への介入やデモ活動の制限といった厳罰化の法制度も積極的に推進されており、厳罰化に向けた新たな制度整備が浮かび上がる。昨今ラテンアメリカでみられる厳罰化の流れのなかで、このようなミレイ政権の事例は厳罰化の背景や制度について示唆に富むものである。PJa/33/Ra2articl
ガーナ最高裁判所長官の罷免――新大統領による長官の停職処分に着目して――
Get PDF2024 年12 月の大統領選挙によって政権交代が生じたガーナでは、ジョン・マハマ（John Mahama）新大統領が、2025 年4 月にガートルード・トルコルヌー（Gertrude Torkornoo）最高裁判所長官を停職する異例の処分を下した。これは長官の罷免を求める請願書3 通が提出されたことをうけた対応である。その後の調査委員会の勧告により9 月1 日付で同長官は罷免された。表向きは長官による越権行為に対する司法の健全性維持を理由とした処分だが、背景には同国の二大政党による勢力争いがある。さらに、この勢力争いは大統領が有す様々な公的ポストの任命権によって助長されている。このような勝者総取り制度と、近年特に高まりをみせている国民の司法への不信感が、今回の処分を後押しした。PJa/3/Af4articl
Integrating Mobile Health Technology into Sleep Research and Environmental Epidemiology
No full textSleep is fundamental to human health. In aspects of both duration and quality, the majority of adults in the United States suffer from suboptimal sleep. During sleep and during wake, through the simultaneous presence of sensory stimuli, neighborhood-level contextual factors, and structural forces that inform our movement through a city, our environments affect our sleep. Sleep is an outcome that individuals experience on a daily basis and environmental exposures are ubiquitous; therefore, interrogations of the relationship between sleep and environment can be highly impactful for advancing public health. Using sleep data collected in the prospective cohort of the Nurses’ Health Study 3, this dissertation explores how mobile health technologies like consumer wearable sleep trackers and smartphone global positioning systems (GPS), as well as exposome-based approaches that aim to capture an individual’s environmental exposures more comprehensively, can increase the depth of insights from sleep research and environmental epidemiology.
In Chapter 2, we quantified differences in sleep measurement between a consumer wearable and a research-grade accelerometer in free-living adults. We observed modest differences in measurement of total sleep time, time in bed, and sleep efficiency between the consumer wearable (Fitbit) and research-standard actigraphy. In Chapter 3, we examined the association between daily GPS-derived walkability exposure and consumer wearable-measured sleep. We did not observe an association between walkability and sleep duration or sleep efficiency. In Chapter 4, we investigated the associations of multiple environmental exposures assessed at the residential address, including greenness, light at night, noise, neighborhood socioeconomic status (SES), and walkability, with self-reported sleep duration and quality. We observed consistent associations between higher neighborhood SES and reduced odds of adverse sleep health outcomes. We also observed protective associations for light at night, and harmful associations for noise and greenness.
With these three dissertation aims, we examined how measurement tools, study design, and exposure assessment approaches can be improved to advance studies of sleep and the environment. We first demonstrated viability for consumer wearables in epidemiologic studies. Then, we illustrated how they can be embedded into a population-level study alongside smartphone GPS to study an environmental exposure, walkability. Finally, we expanded the range of exposures studied with sleep and identified neighborhood SES as a key environmental contextual factor impacting sleep health in the US. Together, this body of work contributes to our understanding of how modifiable environmental exposures can be leveraged to improve sleep on a population-level.Population Health Science
When Workers Won’t Work: How Scientists, Employers, and Social Reformers Understood and Sought Remedies for Industrial Fatigue and Other Workplace Afflictions, 1910-1940
No full textThis dissertation investigates the history of attempts to ameliorate fatigue and other workplace afflictions in the US in the first half of the twentieth century. Bringing together labor history, business history, and the history of science, this dissertation traces how three communities of researchers attempted to apply the emerging sciences of (I) physiology, (II) time and motion, and (III) mind to measure and resolve the intractable problem of industrial fatigue and related workplace maladies. The third group of researchers, championing a mental approach, succeeded in demonstrating, at least to the business community, that the science of studying workers’ minds, rather than their physiology or time and motion, was the key to resolving the labor problem. I argue how, in this process, these scientific approaches invented to wrangle the condition of fatigue sometimes amplified it, transforming fatigue study from a reform-minded initiative to protect workers’ health to a tool for capital to better command its workforce. By using science to pathologize the mental roots of fatigue, researchers promised industry a method for ensuring peaceful workplaces free from discontent and transformed industrial life. As workers variously resisted, sabotaged, and acquiesced to these new initiatives to scientifically collect data about their behaviors, minds, and bodies, they left behind a history of how workers experienced and responded to technological transformations at work.History of Scienc
A Compact Piezoelectric Tilt Table for Cryogenic Electron Microscopy
No full textThis project designed, tested materials and machining techniques, and prototyped a piezoelectrically actuated motor to precisely orient a stage for a specimen within the compact space and restrictive environment of a transmission electron microscope (TEM). TEMs enable researchers to image and probe the structure of materials at the atomic scale, enabling advances in materials science, structural biology, and semiconductor scaling. However, many materials, such as superconductors, must be studied at cryogenic temperatures. Most materials and mechanisms that might be used to orient a specimen will not work at the very low temperatures, high vacuum, and magnetic fields within a TEM. Current specimen tilt stages typically use external DC motors which suffer from mechanical vibrations, instability, imprecision, and thermal drift affecting the specimen. There is a need to develop a tilting stage compact enough to fit within the TEM, precise enough to appropriately orient the specimen, and able to function within the cryogenic TEM environment.Mechanical Engineering S